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lördag 16 november 2019

Aivojen valkea aine ja atraktiinigeeni ATRN(20p13) , T2DM, obesitas ja monosyyttien DPPT-L.

https://link.springer.com/article/10.1007%2Fs10048-017-0515-7
2017 Abstract








Hypomyelinating leukodystrophies are a group of neurodevelopmental disorders that affect proper formation of the myelin sheath in the central nervous system. They are characterized by developmental delay, hypotonia, spasticity, and variable intellectual disability. We used whole exome analysis to study the molecular basis of hypomyelinating leukodystrophy in two sibs from a consanguineous family. A homozygous mutation, c.3068+5G>A, was identified in the ATRN gene, with the consequent insertion of an intronic sequence into the patients’ cDNA and a predicted premature termination of the ATRN polypeptide. ATRN encodes Attractin, which was previously shown to play a critical role in central myelination. Several spontaneous ATRN rodent mutants exhibited impaired myelination which was attributed to oxidative stress and accelerated apoptosis. ATRN can now be added to the growing list of genes associated with hypomyelinating leukodystrophy. The disease seems to be confined to the CNS; however, given the young age of our patients, longer follow-up may be required. Keywords

Attractin Hypomyelination Leukodystrophy 


Lisätietoa tästä geenistä PubMed Gene lähteestä:
 https://www.ncbi.nlm.nih.gov/gene/8455

Also known as MGCA; DPPT-L
Summary This gene encodes both membrane-bound and secreted protein isoforms. A membrane-bound isoform exhibits sequence similarity with the mouse mahogany protein, a receptor involved in controlling obesity. A secreted isoform is involved in the initial immune cell clustering during inflammatory responses that may regulate the chemotactic activity of chemokines. [provided by RefSeq, Apr 2016]
Expression Ubiquitous expression in duodenum (RPKM 20.8), thyroid (RPKM 17.2) and 25 other tissues
 (Kelch-domeenit voi laskea jaksoista ,joissa on GG----Y----W motiivi.
 
  1. NM_001207047.3NP_001193976.1  attractin isoform 4
    Status: REVIEWED
    Description
    Transcript Variant: This variant (4) uses an alternate splice junction at the 3' end of the first exon and differs in the 3' UTR and coding region compared to variant 1. The resulting isoform (4) has distinct N- and C-termini compared to isoform 1. Unlike isoform 1, which is membrane-bound, isoform 4 is secreted.
    Source sequence(s)
    AK293010, AK302730, AL132773, BC101705, DA368237
    UniProtKB/Swiss-Prot
    O75882
    UniProtKB/TrEMBL
    B4DZ36
    Conserved Domains (7) summary
    cd03597
    Location:672804
    (ALP)CLECT_attractin_like: C-type lectin-like domain (CTLD) of the type found in human and mouse attractin (AtrN) and attractin-like protein (ALP). CTLD refers to a domain homologous to the carbohydrate-recognition domains (CRDs) of the C-type lectins. Mouse AtrN (the product of the mahogany gene) has been shown to bind Agouti protein and to function in agouti-induced pigmentation and obesity. Mutations in AtrN have also been shown to cause spongiform encephalopathy and hypomyelination in rats and hamsters. The cytoplasmic region of mouse ALP has been shown to binds to melanocortin receptor (MCR4). Signaling through MCR4 plays a role in appetite suppression. Attractin may have therapeutic potential in the treatment of obesity. Human attractin (hAtrN) has been shown to be expressed on activated T cells and released extracellularly. The circulating serum attractin induces the spreading of monocytes that become the focus of the clustering of non-proliferating T cells.
    cd00041
    Location:23131
    CUB; CUB domain; extracellular domain; present in proteins mostly known to be involved in development; not found in prokaryotes, plants and yeast.
    cd00055
    Location:946991
    EGF_Lam; Laminin-type epidermal growth factor-like domain; laminins are the major noncollagenous components of basement membranes that mediate cell adhesion, growth migration, and differentiation; the laminin-type epidermal growth factor-like module occurs in ...
    sd00038
    Location:385434
    Kelch; KELCH repeat [structural motif]
    pfam01437
    Location:816867
    PSI; Plexin repeat
    pfam13415
    Location:234284
    Kelch_3; Galactose oxidase, central domain
    pfam13854
    Location:274312
    Kelch_5; Kelch motif



    REFERENCE   3  (residues 1 to 1156)
      AUTHORS   Laudes M, Oberhauser F, Schulte DM, Schilbach K, Freude S,
                Bilkovski R, Schulz O, Faust M and Krone W.
      TITLE     Dipeptidyl-peptidase 4 and attractin expression is increased in
                circulating blood monocytes of obese human subjects
      JOURNAL   Exp. Clin. Endocrinol. Diabetes 118 (8), 473-477 (2010)
       PUBMED   20198559
      REMARK    GeneRIF: The levels of both dipeptidyl-peptidase 4 and attractin in
                circulating monocytes were significantly higher in obese subjects
                as compared with levels in lean controls or in subjects with type 2
                diabetes.
    Atraktiinivajeen merkitys. Tutkimuskoe-eläimeltä:)
    https://www.ncbi.nlm.nih.gov/pubmed/19931230 
    2010 Feb 2;1312:145-55. doi: 10.1016/j.brainres.2009.11.027. Epub 2009 Nov 18.
    Abnormal myelinogenesis both in the white and gray matter of the attractin-deficient mv rat.
    Laboratory of Veterinary Pathology, Osaka Prefecture University, Rinku Orai-Kita, Izumisano, Osaka 598-8531, Japan.

    Abstract

    The myelin vacuolation (mv) rat exhibits hypomyelination and vacuole formation in the myelin throughout the CNS, caused by a null mutation in the attractin gene. Myelin alterations in the spinal cord of mv rats progress during postnatal development and are more prominent in the white matter. In contrast, microglial activation is confined to the gray matter of mv rats. We here investigate the distribution and expression patterns of major CNS myelin proteins in the spinal cord of mv rats during the development of the myelin lesions. Immunohistochemical and Western blot analyses demonstrated a considerable reduction in the expression of major CNS myelin proteins both in the white and gray matter of mv rats, which was consistent with the morphological alterations of myelin sheaths. Real-time PCR analysis revealed a significant decrease in expression of proteolipid protein (PLP) mRNA both in the white and gray matter of mv rats. However, there was no significant difference between control and mv rats in the cell number of PLP mRNA-positive oligodendrocytes either in the white or gray matter, suggesting an impairment of myelin protein production by oligodendrocytes. Our results indicate that myelinogenesis but not oligodendrogenesis is severely altered both in the white and gray matter of mv rats.
    PMID:
    19931230
    DOI:
    10.1016/j.brainres.2009.11.027

måndag 11 november 2019

Myelinaatio ja Dyneiini

https://www.ncbi.nlm.nih.gov/pubmed/23167977
 
2012 Nov 20;7:37. doi: 10.1186/1749-8104-7-37. Schwann cell myelination requires Dynein function. Langworthy MM1, Appel B.
Department of Pediatrics, University of Colorado School of Medicine, MS 8108, Aurora, CO, 80045, USA. Abstract  BACKGROUND: Interaction of Schwann cells with axons triggers signal transduction that drives expression of Pou3f1 and Egr2 transcription factors, which in turn promote myelination. Signal transduction appears to be mediated, at least in part, by cyclic adenosine monophosphate (cAMP) because elevation of cAMP levels can stimulate myelination in the absence of axon contact. The mechanisms by which the myelinating signal is conveyed remain unclear. RESULTS: By analyzing mutations that disrupt myelination in zebrafish, we learned that Dynein cytoplasmic 1 heavy chain 1 (Dync1h1), which functions as a motor for intracellular molecular trafficking, is required for peripheral myelination. In dync1h1 mutants, Schwann cell progenitors migrated to peripheral nerves but then failed to express Pou3f1 and Egr2 or make myelin membrane. Genetic mosaic experiments revealed that robust Myelin Basic Protein expression required Dync1h1 function within both Schwann cells and axons. Finally, treatment of dync1h1 mutants with a drug to elevate cAMP levels stimulated myelin gene expression. CONCLUSION: Dync1h1 is required for retrograde transport in axons and mutations of Dync1h1 have been implicated in axon disease. Our data now provide evidence that Dync1h1 is also required for efficient myelination of peripheral axons by Schwann cells, perhaps by facilitating signal transduction necessary for myelination.
PMID:
23167977
PMCID:
PMC3520773
DOI:
10.1186/1749-8104-7-37
[Indexed for MEDLINE]
Free PMC Article

torsdag 7 november 2019

KBTBD3 /BKLHD3

Tutkimusten alainen Kelch-superperheen  KBTBD-ryhmän  proteiini , jota  ilmentyy eniten aivoissa, siten kilpirauhasessa ja useissa muissa kudoksissa . https://genecards.weizmann.ac.il/v3/cgi-bin/carddisp.pl?gene=KBTBD3: Funktio pohdittavana.
https://genecards.weizmann.ac.il/v3/cgi-bin/carddisp.pl?gene=KBTBD3

HGNC Gene Families:

BTBD: BTB/POZ domain containing

Selected InterPro protein domains (see all 7):

 IPR017096 Kelch-like_gigaxonin-typ
 IPR000210 BTB/POZ-like
 IPR006652 Kelch_1
 IPR011333 BTB/POZ_fold
 IPR013069 BTB_POZ

Graphical View of Domain Structure for InterPro Entry Q8NAB2
ProtoNet protein and cluster: Q8NAB2
2 Blocks protein domains:
IPB000210 BTB/POZ domain
IPB011705 BTB/Kelch-associated


UniProtKB/Swiss-Prot: KBTB3_HUMAN, Q8NAB2
Similarity: Contains 1 BACK (BTB/Kelch associated) domain
Similarity: Contains 1 BTB (POZ) domain
Similarity: Contains 5 Kelch repeats

Koetan hahmottaa rakennetta ja verrata esim  gigaxoniin, onko jotain tai mitään  samaa sekvenssipätkää) Kesken...Minkälainen Znf?


 KBTBD3,https://www.ncbi.nlm.nih.gov/gene/143879
Also known as
BKLHD3
Expression
Ubiquitous expression in brain (RPKM 1.9), thyroid (RPKM 1.3) and 25 other tissues See more
Orthologs
       ##Evidence-Data-END##
FEATURES             Location/Qualifiers
     source          1..533
                     /organism="Homo sapiens"
                     /db_xref="taxon:9606"
                     /chromosome="11"
                     /map="11q22.3"
     Protein         1..533
                     /product="kelch repeat and BTB domain-containing protein 3
                     isoform 2"
                     /note="BTB and kelch domain containing 3; kelch repeat and
                     BTB domain-containing protein 3; BTB and kelch
                     domain-containing protein 3; kelch repeat and BTB (POZ)
                     domain containing 3; epididymis secretory sperm binding
                     protein"
                     /calculated_mol_wt=60545
     Region          16..507
                     /region_name="BTB"
                     /note="Broad-Complex, Tramtrack and Bric a brac; cl28614"
                     /db_xref="CDD:333434"
     Region          255..310
                     /region_name="KELCH repeat"
                     /note="KELCH repeat [structural motif]"
                     /db_xref="CDD:276965"
     Region          314..362
                     /region_name="KELCH repeat"
                     /note="KELCH repeat [structural motif]"
                     /db_xref="CDD:276965"
     Region          365..410
                     /region_name="KELCH repeat"
                     /note="KELCH repeat [structural motif]"
                     /db_xref="CDD:276965"
     Region          462..507
                     /region_name="KELCH repeat"
                     /note="KELCH repeat [structural motif]"
                     /db_xref="CDD:276965"
     CDS             1..533
                     /gene="KBTBD3"
                     /gene_synonym="BKLHD3"
                     /coded_by="NM_001330359.1:633..2234"
                     /note="isoform 2 is encoded by transcript variant 3"
                     /db_xref="CCDS:CCDS81621.1"
                     /db_xref="GeneID:143879"
                     /db_xref="HGNC:HGNC:22934"
ORIGIN      
        1 mfevnmkerd dgsvtitnls skavkafldy aytgktkitd dnvemffqls sflqvsflsk
       61 acsdfliksi nlvnclqlls isdsygstsl fdhalhfvqh hfsllfkssd flemnfgvlq
      121 kclesdelnv peeemvlkvv lswtkhnles rqkylphlie kvrlhqlsee tlqdclfnee
      181 sllkstncfd iimdaikcvq gsgglfpdar psttekyifi hkteengenq ytfcyniksd
      241 swkilpqshl idlpgsslss ygekifltgg ckgkccrtvr lhiaesyhda tdqtwcycpv
      301 kndfflvstm ktprtmhtsv maldrlfvig gktrgsrdik slldvesynp lskewisvsp
      361 lprgiyypea stcqnviyvl gseveitdaf npsldcffky nattdqwsel vaefgqffha
      421 tlikavpvnc tlyicdlsty kvysfcpdtc vwkgegsfec agfnagaigi edkiyilggd
      481 yapdeitdev qvyhsnrsew eevspmpral tefycqviqf nkyrdpwfsn lca
//

https://www.ncbi.nlm.nih.gov/pubmed/?term=KBTBD3

VERTAA GIGAXONIINI sekvenssiin,  KLHL16:
ORIGIN      
        1 maegsavsdp qhaarllral ssfreesrfc dahlvldgee ipvqknilaa aspyirtkln
       61 ynppkddgst ykielegisv mvmreildyi fsgqirlned tiqdvvqaad lllltdlktl
      121 cceflegcia aencigirdf alhyclhhvh ylateyleth frdvssteef lelspqklke
      181 visleklnvg neryvfeavi rwiahdteir kvhmkdvmsa lwvsgldssy lreqmlnepl
      241 vreivkecsn iplsqpqqge amlanfkprg ysecivtvgg eervsrkpta amrcmcplyd
      301 pnrqlwiela plsmprinhg vlsaegflfv fggqdenkqt lssgekydpd antwtalppm
      361 nearhnfgiv eidgmlyilg gedgekelis mecydiyskt wtkqpdltmv rkigcyaamk
      421 kkiyamgggs ygklfesvec ydprtqqwta icplkerrfg avacgvamel yvfggvrsre
      481 daqgsemvtc ksefyhdefk rwiylndqnl cipasssfvy gavpigasiy vigdldtgtn
      541 ydyvrefkrs tgtwhhtkpl lpsdlrrtgc aalrianckl frlqlqqglf rirvhsp
//

onsdag 6 november 2019

ACLY entsyymi kolinergisessä neuronissa ym. (2019)

https://www.ncbi.nlm.nih.gov/pubmed/30944476
2019 Apr;568(7753):571-575. doi: 10.1038/s41586-019-1095-5. Epub 2019 Apr 3.

Structure of ATP citrate lyase (ACLY)  and the origin of citrate synthase(CS)  in the Krebs cycle.

1Unit for Structural Biology, VIB Center for Inflammation Research, Ghent, Belgium.
2Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.3European Molecular Biology Laboratory (EMBL), Hamburg Outstation c/o DESY, Hamburg, Germany.4University of Grenoble Alpes, CNRS, CEA, CNRS, IBS, Grenoble, France.5Integrated Molecular Plant Physiology Research, Department of Biology, University of Antwerp, Antwerp, Belgium.6Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.7Unit for Structural Biology, VIB Center for Inflammation Research, Ghent, Belgium. kenneth.verstraete@ugent.be.8Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium. kenneth.verstraete@ugent.be.

Abstract

Across different kingdoms of life, ATP citrate lyase (ACLY, also known as ACL) catalyses the ATP-dependent and coenzyme A (CoA)-dependent conversion of citrate, a metabolic product of the Krebs cycle, to oxaloacetate and the high-energy biosynthetic precursor acetyl-CoA1. The latter fuels pivotal biochemical reactions such as the synthesis of fatty acids, cholesterol and acetylcholine2, and the acetylation of histones and proteins3,4. In autotrophic prokaryotes, ACLY is a hallmark enzyme of the reverse Krebs cycle (also known as the reductive tricarboxylic acid cycle), which fixates two molecules of carbon dioxide in acetyl-CoA5,6. In humans, ACLY links carbohydrate and lipid metabolism and is strongly expressed in liver and adipose tissue1 and in cholinergic neurons2,7.

 The structural basis of the function of ACLY remains unknown. Here we report high-resolution crystal structures of bacterial, archaeal and human ACLY, and use distinct substrate-bound states to link the conformational plasticity of ACLY to its multistep catalytic itinerary. Such detailed insights will provide the framework for targeting human ACLY in cancer8,9,10,11 and hyperlipidaemia12,13. Our structural studies also unmask a fundamental evolutionary relationship that links citrate synthase, the first enzyme of the oxidative Krebs cycle, to an ancestral tetrameric citryl-CoA lyase module that operates in the reverse Krebs cycle. This molecular transition marked a key step in the evolution of metabolism on Earth.

KLHL25(ENC-2) ja ATP:sitraattilyaasi ACLY

 Kelch- superperheen proteiini KLHL25 toimii adaptorina kun CUL3  johtaa ATP:sitraattilyaasia proteosomisilppuriin. 

Entä miten nämä toimivat aivossa?
Aivossa tarvitaan  jatkuvaa rasva-aine ja kolesterolisynteesiä, koska aivo on  rasvamoduli, koostunut hyvin monimutkaisista j monipuolisista lipidiaineista.  Lisäksi neuronit tarvitsevat AcetylCoaa  muodostamaan hermonvälittäjäainetta asetylkoliinia kolinergisessä järjestelmässä. Se toimii eräänlaisena clearing-tekijänä   hermoissa ja  varsinkin tahdonalaisessa ajattelussa ja toiminnassa se on tärkeä.   hermorata. Löytyykö jotain konkreettista karttaa  sitraatista, kelch-proteiinifunktiosta,  ja yhteydestä muihin  elementaarisiin etikkahapon ja sitruunahapon tasoa kuvaaviin kaavoihin?


Cullin3KLHL25 ubiquitin ligase targetsACLY for degradation to inhibit lipidsynthesis and tumor progression

 Cen Zhang,1,4Juan Liu,1,4Grace Huang,2Yuhan Zhao,1Xuetian Yue,1Hao Wu,1Jun Li,1Junlan Zhu,2Zhiyuan Shen,1Bruce G. Haffty,1Wenwei Hu,1and Zhaohui Feng1,31Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers University, The State Universityof New Jersey, New Brunswick, New Jersey 08903, USA;2Nelson Institute of Environmental Medicine, New York UniversitySchool of Medicine, New York University, Tuxedo, New Jersey 10987, USA;3Department of Pharmacology, Rutgers University,The State University of New Jersey, Piscataway, New Jersey 08854, USA

 Increased lipid synthesis is a key characteristic of many cancers that is critical for cancer progression. ATP-citratelyase (ACLY), a key enzyme for lipid synthesis, is frequently overexpressed or activated in cancer to promote lipidsynthesis and tumor progression. Cullin3 (CUL3), a core protein for the CUL3RING ubiquitin ligase complex, has been reported to be a tumor suppressor and frequently down-regulated in lung cancer. Here, we found that CUL3interacts with ACLY through its adaptor protein, KLHL25 (Kelch-like family member 25), to ubiquitinate anddegrade ACLY in cells. Through negative regulation of ACLY, CUL3 inhibits lipid synthesis, cell proliferation,and xenograft tumor growth of lung cancer cells. Furthermore, ACLY inhibitor SB-204990 greatly abolishes thepromoting effect of CUL3 down-regulation on lipid synthesis, cell proliferation, and tumor growth. Importantly, lowCUL3 expression is associated with high ACLY expression and poor prognosis in human lung cancer. In summary,our results identify CUL3KLHL25 ubiquitin ligase as a novel negative regulator for ACLY and lipid synthesis anddemonstrate that decreased CUL3 expression is an important mechanism for increased ACLY expression and lipidsynthesis in lung cancer. These results also reveal that negative regulation of ACLY and lipid synthesis is a novel andcritical mechanism for CUL3 in tumor suppression.[Keywords: CUL3; ACLY; KLHL25; ubiquitination; lipid synthesis; tumor 

 Image result for citrate synthase,  citrate lyase


https://www.ncbi.nlm.nih.gov/pubmed/28161643

SIRT3 have been found to be neuroprotective in many neurological diseases, but its detail mechanism is only partially understood. In this study, MPP+ was used to treat SH-SY5Y cells as the cellular model of PD to test the role of SIRT3 and the mechanism may be involved in. We focused on the changes and relationship between SIRT3 and the key mitochondrial enzymes citrate synthase (CS) and isocitrate dehydrogenase 2 (IDH2). We found MPP+ decreased SIRT3 expression. And our results showed that the enzymatic activities of CS and IDH2 were significantly reduced in MPP+ treatment cells, while protein acetylation of CS and IDH2 increased. However overexpressed-SIRT3 partially reversed at least, the decline of CS activity and the increase of CS protein acetylation. IDH2 did not showed the same changes. The study suggested that SIRT3 deacetylated and activated CS activity. Hence, we conclude that SIRT3 exhibits neuroprotection via deacetylating and increasing mitochondrial enzyme activities.
Deacetylation; Enzyme activity; Mitochondria; Neuroprotection; Parkinson disease; SIRT3

https://i.pinimg.com/originals/b0/bd/44/b0bd4471753eb332a4d601c7e065ee6e.jpg 

 https://i.pinimg.com/originals/b0/bd/44/b0bd4471753eb332a4d601c7e065ee6e.jpg

ENC-1 (KLHL37) (5q13.3) Tumamatrixproteiini aivoissa, rajoittaa NRF2:n translatoitumista.

https://www.ncbi.nlm.nih.gov/gene/8507

Also known as
NRPB; CCL28; ENC-1; PIG10; KLHL35; KLHL37; TP53I10
Summary
This gene encodes a member of the kelch-related family of actin-binding proteins. The encoded protein plays a role in the oxidative stress response as a regulator of the transcription factor Nrf2, and expression of this gene may play a role in malignant transformation. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Feb 2012]
Expression
Biased expression in brain (RPKM 180.1), gall bladder (RPKM 11.8) and 4 other tissues See more
Orthologs

KLHL16 (16q23.2), Gigaxoniini, GAN . Mutaatioiden merkitys.

https://www.ncbi.nlm.nih.gov/gene/8139

Edellisen KLHL1 geenin löytöä  käsittelevän  tekstin sitaatissa oli seuraavat lauseet:  

..."The Kelch-related proteins have diverse functions in cell morphology, cell organization, and gene expression, and function in multiprotein complexes through contact sites in their β-propeller domains (14). Recently, a new member of the BTB/Kelch repeat family, gigaxonin (GAN, KLHL16), was reported to be a pathological target for neurodegenerative disorders in which alterations were found to contain multiple mutations in the Kelch repeats in the neurofilament network (15)." tarkistan viitteen 15:

  https://www.nature.com/articles/ng1100_370
 Published:




The gene encoding gigaxonin, a new member of the cytoskeletal BTB/kelch repeat family, is mutated in giant axonal neuropathy


Abstract



Disorganization of the neurofilament network is a prominent feature of several neurodegenerative disorders including amyotrophic lateral sclerosis (ALS), infantile spinal muscular atrophy and axonal Charcot-Marie-Tooth disease1,2,3,4. Giant axonal neuropathy (GAN, MIM 256850), a severe, autosomal recessive sensorimotor neuropathy affecting both the peripheral nerves and the central nervous system, is characterized by neurofilament accumulation, leading to segmental distension of the axons5,6. GAN corresponds to a generalized disorganization of the cytoskeletal intermediate filaments (IFs), to which neurofilaments belong, as abnormal aggregation of multiple tissue-specific IFs has been reported: vimentin in endothelial cells, Schwann cells and cultured skin fibroblasts, and glial fibrillary acidic protein (GFAP) in astrocytes7,8,9,10,11. Keratin IFs also seem to be alterated, as most patients present characteristic curly or kinky hairs12.

 We report here identification of the gene GAN, which encodes a novel, ubiquitously expressed protein we have named gigaxonin. We found one frameshift, four nonsense and nine missense mutations in GAN of GAN patients. Gigaxonin is composed of an amino-terminal BTB (for Broad-Complex, Tramtrack and Bric a brac) domain followed by a six kelch repeats, which are predicted to adopt a β-propeller shape13. Distantly related proteins sharing a similar domain organization have various functions associated with the cytoskeleton, predicting that gigaxonin is a novel and distinct cytoskeletal protein that may represent a general pathological target for other neurodegenerative disorders with alterations in the neurofilament network.

KLHL1(13q21.33) , MRP2. Oligodendrosyytille tärkeä Mayvenin sukuinen MRP2 = Kelch proteiini 1)

http://www.jbc.org/content/282/16/12319.long
 Tutkijat luonnehtivat uuden Kelch proteiinin joka on KLHL1 kaltainen ja Mayvenin sukuinen MPR2.  Se osoittautuu tärkeäksi merkitsijäksi oligodenrosyyttien elämässä.

Process Elongation of Oligodendrocytes Is Promoted by the Kelch-related Protein MRP2/KLHL1*
Shuxian Jiang1, Seyha Seng1, Hava Karsenty Avraham, Yigong Fu and Shalom Avraham2
  1. Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115
  1. 2 To whom correspondence should be addressed: 4 Blackfan Circle, Boston, MA 02115. Tel.: 617-667-0063; Fax: 617-975-6373 or 617-975-5240; E-mail: savraham{at}bidmc.harvard.edu.
Abstract
Oligodendrocytes (OLGs) are generated by progenitor cells that are committed to differentiating into myelin-forming cells of the central nervous system. Rearrangement of the cytoskeleton leading to the extension of cellular processes is essential for the myelination of axons by OLGs. Here, we have characterized a new member of the Kelch-related protein family termed MRP2 (for Mayven-related protein 2) that is specifically expressed in brain. MRP2/KLHL1 is expressed in oligodendrocyte precursors and mature OLGs, and its expression is up-regulated during OLG differentiation. MRP2/KLHL1 expression was abundant during the specific stages of oligodendrocyte development, as identified by A2B5-, O4-, and O1-specific oligodendrocyte markers. MRP2/KLHL1 was localized in the cytoplasm and along the cell processes. Moreover, a direct endogenous association of MRP2/KLHL1 with actin was observed, which was significantly increased in differentiated OLGs compared with undifferentiated OLGs. Overexpression of MRP2/KLHL1 resulted in a significant increase in the process extension of rat OLGs, whereas MRP2/KLHL1 antisense reduced the process length of primary rat OLGs. Furthermore, murine OLGs isolated from MRP2/KLHL1 transgenic mice showed a significant increase in the process extension of OLGs compared with control wild-type murine OLGs. These studies provide insights into the role of MRP2/KLHL1, through its interaction with actin, in the process elongation of OLGs.

Oligodendrocytes (OLGs)3 are a major cell type in the central nervous system. Development of these cells is necessary for normal functioning of the brain, and injury to them is involved in the pathogenesis of important neurological disorders including cerebral palsy, multiple sclerosis, and periventricular leukomalacia (1, 2). OLGs represent the myelin-forming cells of the central nervous system. They produce numerous membranous processes, which spirally enwrap neuronal axons, forming multilamellar myelin sheaths (3, 4). OLGs are metabolically the most active cells in the brain (5). Before OLGs can remyelinate, they must first be able to extend their processes, and contact the demyelinated axons. However, the molecules involved in the mechanisms of OLG process extension are poorly defined.
A new and unique family of actin-binding proteins with sequences and domains homologous with the Drosophila “Kelch” protein has emerged (6). Kelch protein is believed to be important for the maintenance of the ordered cytoskeleton (7, 8). The Kelch protein has two structural domains that are also found in other molecules. The first domain, which consists of about 115 amino acids, has been named the BTB (Bric-a-brac, Tramtrack, Broad-complex) domain (9) or POZ (Poxvirus zinc finger) domain (10). The second domain, composed of about 50 amino acids repeated in tandem, has been called the “Kelch repeats.” The BTB/POZ domain has been proposed to function as a protein-protein interaction interface, which organizes higher order structures involved in chromatin folding or cytoskeleton organization (11). 


The Kelch-related proteins are a superfamily of proteins conserved in a wide range of organisms, from viruses to mammals. At least 60 Kelch-related proteins have been identified, but their physiological and biochemical functions remain largely uncharacterized (12, 13). The Drosophila Kelch proteins colocalize with actin filaments in a structure called the ring canal, which bridges 15 nurse cells and the oocyte. Drosophila Kelch protein plays an important role in maintaining actin organization during the development of ring canals (6, 8).

The Kelch-related proteins have diverse functions in cell morphology, cell organization, and gene expression, and function in multiprotein complexes through contact sites in their β-propeller domains (14). Recently, a new member of the BTB/Kelch repeat family, gigaxonin (GAN, KLHL16), was reported to be a pathological target for neurodegenerative disorders in which alterations were found to contain multiple mutations in the Kelch repeats in the neurofilament network (15).
We have previously identified and characterized two actinbinding proteins, termed NRP/B/ENC-1 (KLHL37, PIG10 TP5310 ,5q13.3) (16-18) and Mayven (KHLH24q32.3)  (19), predominantly expressed in brain. Mayven is an actin-binding protein that is co-localized with actin filaments in stress fibers and in the patchy cortical actin-rich regions of the cell margins and processes, including the process tips in primary neurons and U373-MG astrocytoma/glioblastoma cells (19). During our study of proteins that are related to Mayven, we identified and cloned a novel gene, which we termed: MRP2 (Mayven-related protein 2) that was found to be identical to KLHL1 (20, 21). In this study, we have investigated the expression of MRP2/KLHL1 in OLGs and its possible role in the dynamics of cytoskeletal rearrangement, leading to the elongation of OLG processes.

Oligodendrocytes (OLGs)3 are a major cell type in the central nervous system. Development of these cells is necessary for normal functioning of the brain, and injury to them is involved in the pathogenesis of important neurological disorders including cerebral palsy, multiple sclerosis, and periventricular leukomalacia (1, 2). OLGs represent the myelin-forming cells of the central nervous system. They produce numerous membranous processes, which spirally enwrap neuronal axons, forming multilamellar myelin sheaths (3, 4). OLGs are metabolically the most active cells in the brain (5). Before OLGs can remyelinate, they must first be able to extend their processes, and contact the demyelinated axons. However, the molecules involved in the mechanisms of OLG process extension are poorly defined.
A new and unique family of actin-binding proteins with sequences and domains homologous with the Drosophila “Kelch” protein has emerged (6). Kelch protein is believed to be important for the maintenance of the ordered cytoskeleton (7, 8). The Kelch protein has two structural domains that are also found in other molecules. The first domain, which consists of about 115 amino acids, has been named the BTB (Bric-a-brac, Tramtrack, Broad-complex) domain (9) or POZ (Poxvirus zinc finger) domain (10). The second domain, composed of about 50 amino acids repeated in tandem, has been called the “Kelch repeats.” The BTB/POZ domain has been proposed to function as a protein-protein interaction interface, which organizes higher order structures involved in chromatin folding or cytoskeleton organization (11).
The Kelch-related proteins are a superfamily of proteins conserved in a wide range of organisms, from viruses to mammals. At least 60 Kelch-related proteins have been identified, but their physiological and biochemical functions remain largely uncharacterized (12, 13). The Drosophila Kelch proteins colocalize with actin filaments in a structure called the ring canal, which bridges 15 nurse cells and the oocyte. Drosophila Kelch protein plays an important role in maintaining actin organization during the development of ring canals (6, 8). The Kelch-related proteins have diverse functions in cell morphology, cell organization, and gene expression, and function in multiprotein complexes through contact sites in their β-propeller domains (14). Recently, a new member of the BTB/Kelch repeat family, gigaxonin, was reported to be a pathological target for neurodegenerative disorders in which alterations were found to contain multiple mutations in the Kelch repeats in the neurofilament network (15).
We have previously identified and characterized two actinbinding proteins, termed NRP/B/ENC-1 (16-18) and Mayven (19), predominantly expressed in brain. Mayven is an actin-binding protein that is co-localized with actin filaments in stress fibers and in the patchy cortical actin-rich regions of the cell margins and processes, including the process tips in primary neurons and U373-MG astrocytoma/glioblastoma cells (19). During our study of proteins that are related to Mayven, we identified and cloned a novel gene, which we termed: MRP2 (Mayven-related protein 2) that was found to be identical to KLHL1 (20, 21). In this study, we have investigated the expression of MRP2/KLHL1 in OLGs and its possible role in the dynamics of cytoskeletal rearrangement, leading to the elongation of OLG processes.

KLHL32(6q16.1) Kelch-proteiini ilmentyy miltei yksinomaan keskushermostossa.

 1)  http://www.ebi.ac.uk/interpro/entry/InterPro/IPR030570/
 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3658946/figure/F1/

2)  https://www.ncbi.nlm.nih.gov/pubmed/23253088

Abstract

Tourette Syndrome (TS) is a neuropsychiatric disorder in children characterized by motor and verbal tics. Although several genes have been suggested in the etiology of TS, the genetic mechanisms remain poorly understood.
Using cytogenetics and FISH analysis, we identified an apparently balanced t(6,22)(q16.2;p13) in a male patient with TS and obsessive-compulsive disorder (OCD). In order to map the breakpoints and to identify additional submicroscopic rearrangements, we performed whole genome mate-pair sequencing and CGH-array analysis on DNA from the proband.
Sequence and CGH array analysis revealed a 400 kb deletion located 1.3 Mb telomeric of the chromosome 6q breakpoint, which has not been reported in controls. The deletion affects three genes (GPR63, NDUFA4 and KLHL32) and overlaps a region previously found deleted in a girl with autistic features and speech delay.
 Figure 2

 The proband's mother, also a carrier of the translocation, was diagnosed with OCD and shares the deletion. We also describe a further potentially related rearrangement which, while unmapped in Homo sapiens, was consistent with the chimpanzee genome.
We conclude that genome-wide sequencing at relatively low resolution can be used for the identification of submicroscopic rearrangements. We also show that large rearrangements may escape detection using standard analysis of whole genome sequencing data. Our findings further provide a candidate region for TS and OCD on chromosome 6q16.
PMID:
23253088
PMCID:
PMC3556158
DOI:
10.1186/1471-2350-13-123
[Indexed for MEDLINE]
Free PMC Article

KLHL2(Mayven) ja KLHL17 ( Actinofiliini) osallistuvat KAR degradaatioon ja GluR6 säätelyyn

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3929045/
. Author manuscript; available in PMC 2014 Feb 19.
Published in final edited form as:
PMCID: PMC3929045
NIHMSID: NIHMS555194
PMID: 21713671

BTB-Kelch Proteins and Ubiquitination of Kainate Receptors

Kainate receptors (KAR) form a class of glutamate receptors that have been implicated in epilepsy, stroke, Alzheimer’s and neuropathic pain. KAR subtypes are known to be segregated to specific locations within neurons and play significant roles in synaptic transmission and plasticity. Increasing evidence suggests a the role for ubiqutination in regulating the number of synaptic neurotransmitter receptors. The ubiquitin pathway consists of activation (E1), conjugation (E2) and ligation (E3). Cullins form the largest family of E3 ligase complexes. We have recently shown that the BTB/Kelch domain proteins, actinfilin  (KLHL17 , 1p36.33, https://www.ncbi.nlm.nih.gov/gene/339451#gene-expression) and mayven (KLHL2, 4q32.3,https://www.ncbi.nlm.nih.gov/gene/11275O , bind both Cul3 and specific KAR subtypes (GluR6 and GluR5-2b) to target these KARs for ubiquitination and degradation. In this chapter we will review how these interactions occur, what they mean for the stability of KARs and their associated proteins and how, in turn, they may affect synaptic functions in the central nervous system.

Introduction
KARs are found pre and postsynaptically and have been implicated in the etiology of epilepsy, as well as stroke-induced neurodegeneration and Huntington’s disease., Epilepsy occurs when inhibitory adaptation is unable to prevent excess neural activity. The developing cortex is particularly vulnerable and a number of syndromes are associated with epilepsy at an early age. Postsynaptic injection of kainic acid causes epileptiform discharges and the death of hippocampal CA3 pyramidal neurons., Moreover, KARs are subject to developmental and activity-dependent regulation at thalamocortical synapses and are likely to play an important role in the development of hippocampal synaptic circuits. KARs act as excitatory glutamate- gated ion channels: KAR-mediated excitatory postsynaptic currents were first described at mossy fiber-CA3 pyramidal cell synapses,, while presynaptically, activation of KARs on inhibitory interneurons decreases GABA release which acts to enhance electrical activity, suggesting that presynaptic KARs may be epileptigeneic. Notably, the GluR6 subtype of KARs can also increase neuronal excitability via metabotropic regulation of potassium channels. To treat pathological conditions it will be crucial to understand the molecular mechanisms that determine localization of specific KARs to specific membrane domains.
Within KARs, there is a considerable diversity of properties, including unitary channel conductance, Ca2+ permeability and rectification, which arise from differences in receptor subunit composition and RNA editing of GluR5 and GluR6. KARs are tetramers that can be assembled from any one of five receptor subunits encoded by two separate gene families. The first of these includes receptor subunits GluR5, -6 and -7. Each of these subunits can form functional homomeric ion channels or heteromeric mixtures that appear to assemble promiscuously with any available subunit GluR5, -6 or -7. Alternative splicing of GluR5 yields two isoforms: GluR5-1 and GluR5-2, which has three additional splice variants possessing distinct C-terminal sequences. The shortest variant is designated GluR5-2a, while additional exons located in the C-terminal region give rise to GluR5-2b and GluR5-2c; these variants share a C-terminal type 1 PDZ-binding domain that is absent in GluR5-2a. The second gene family consists of KA1 and KA2 subunits that are functional only when expressed as heteromeric assemblies with GluR5, -6 or -7.,
Alternative splicing and RNA editing of ionotropic glutamate receptors play important roles in receptor assembly and trafficking. Regulatory steps in the assembly of KA2-containing KARs are governed by at least two trafficking signals located in the cytoplasmic terminal (C-tail) of the KA2 subunit. The first is an arginine(R)-rich motif which operates as an endoplasmic reticulum (ER) retention signal preventing the insertion of homomeric KA2 receptors into the plasma membrane. The second is a di-leucine motif (LL) which mediates the internalization and subsequent relocalization of surface-expressed KA2 subunits. Similarly, GluR5-2b carries a positively charged amino acid motif that acts as a novel ER retention signal. In contrast, GluR6, which is highly expressed at the plasma membrane, has a forward trafficking signal in its C-terminal domain critical for ER exit.,
These differences in targeting appear to convey specific roles to specific KAR subtypes: In GluR6 knockout mice, mossy fiber long-term potentiation (LTP) was reduced, whereas GluR5 knockout mice exhibited normal LTP. The activation of KARs also modulates neurotransmitter release from a number of hippocampal synapses, including GABA release at inhibitory terminals that synapse onto CA1 pyramidal cells., In hippocampal slices, kainate depresses GABA-mediated synaptic inhibition and increases the firing rate of interneurons. These effects are explained by two populations of KARs in CA1 interneurons: GluR6/KA2 located in the somatodendritic compartment and GluR5-GluR6 or GluR5-KA2 at presynaptic terminals. It is anticipated that this segregation of KARs will allow us to design drugs that specifically target each function.
Recent evidence suggests that the ubiquitin-proteasome pathway and synaptic activity affects the composition of postsynaptic proteins. The addition of ubiquitin to proteins leads to a variety of fates for the tagged proteins, one of which is degradation by the 26S proteasome. A family of proteins called E3 ligases determines the specificity of ubiquitin addition. E3 ligases frequently consist of a complex of proteins that act together for specific substrate binding and ubiquitin ligation activity. Two major families of E3 ligases have been described: the HECT-domain family that is defined by its homology to the C-terminus of E6-associated protein (E6AP) and the RING family that contains either an intrinsic RING-finger domain or an associated RING-finger protein subunit essential for ubiquitin ligase activity. One of the best-characterized subset of the RING E3 ligases is the Skp1/Cul1/F-box protein complex (SCF), in which Cul1 binds an adaptor molecule, Skp1., Skp1 associates with an F-box protein that in turn binds a phosphorylated substrate. The Cul1 component of the SCF E3 ligase belongs to an evolutionarily conserved family of proteins known as cullins, of which there are six closely related members (Cul1, 2, 3, 4A, 4B and 5) and three distant relatives (Cul7, Parc and APC2).
A major class of Kelch proteins, defined as containing a 6-fold tandem “kelch” element, contains an N-terminal BTB/POZ domain and C-terminal kelch repeats and targets different substrates to the Cul3-Roc1 catalytic core. For example, the BTB-Kelch protein Keap1 (KLHL19), a negative regulator of the transcription factor Nrf2, binds Cul3 and Nrf2 via its BTB and kelch domains, respectively, targeting Nrf2 for ubiquitination and subsequent degradation by the proteasome. The BTB-Kelch family also includes the closely related protein mayven (KLHL2) , an actin-binding protein and gigaxonin (KLHL16, GAN), which is mutated in a human autosomal recessive neurodegenerative disorder named giant axonal neuropathy. Mutations in E3 ubiquitin ligases have also been associated with Parkinson’s disease and breast cancer.

KAR Regulation by the Ubiquitin-Proteasome Pathway

To search for proteins involved in the regulation of KARs, we performed a yeast two-hybrid screen of an adult rat brain cDNA library using the C-terminus of GluR6 as bait. Strong interactions were detected between GluR6 and actinfilin (KLHL17, Actinfilin (AF) is a novel BTB/Kelch protein that was identified as a brain-specific actin-binding protein in postsynaptic densities (PSDs). Co-immunoprecipitation studies performed using HEK293 cell and rat brain extracts show that actinfilin binds GluR6 and GluR5-2b, but not with other glutamate receptors and ion channels. Because actinfilin is highly similar to another brain BTB/Kelch protein member, mayven (KLHL2)   (55% amino acid identity), we cloned this cDNA and, upon expression, found that it also co-immuno-precipitated with GluR6.
Actinfilin (KLHL17)  was found to interact with Cul3 to promote proteasomal degradation of GluR6 in vitro and in vivo. Expression of GluR6 with an HA-tagged ubiquitin (Ub-HA) in HEK293 cells showed a characteristic ladder indicating that GluR6 was ubiquitinated. Conversely, treatment with the 26S proteasomal inhibitor, MG132, greatly enhanced ubiquitination and stabilized GluR6 expression, demonstrating that GluR6 protein is fairly short-lived. Furthermore, co-immunoprecipitation studies verified that actinfilin interacts with Cul3, but not Cul1, in brain. The interactions of cullins with their adaptors o%en cause mutual degradation. Importantly, Cul3 appears to specifically regulate KAR levels in vivo (Fig. 1): In synaptosomes prepared from heterozygous Cul3 knockout mice, GluR6 levels are substantially increased, a small effect is observed on KA2 levels, but significantly, no effect on AMPA or NMDA receptors can be detected. These data suggest that Cul3 promotes degradation of KARs.We also found that actinfilin (AF) (KLHL17) was localized synaptically in hippocampal and cortical neurons and that it negatively regulates KAR expression (Fig. 2). A high degree of colocalization of AF and GluR6 was observed in dendritic spines. To establish tools to determine the role of actinifilin in the trafficking and/or synaptic localization of GluR6, we have developed a short hairpin inhibitory RNA (RNAi) to actinfilin that eliminates actinifilin expression (Fig. 2D). Specifically, we found that decreasing actinfilin levels via RNAi and overexpressing an inactive Cul3 both induced increased surface GluR6 expression at synapses, suggesting that actinfilin-Cul3-mediated degradation may provide an important mechanism for regulating neuronal GluR6.
Proposed regulation of KARs by AF and Cul3. The Cul3-based E3 ligase consists of Cul3, which acts as a scaffold to bring several essential proteins in close proximity. These proteins include Nedd 8 (Nd8), Rbx1 and a ubiquitin conjugating enzyme (E2). Substrate specificity is mediated by proteins containing a BTB domain that bind Cul3 in its amino-terminal end. Other domains on the BTB domain-containing proteins are involved in recognition of substrates; in the cases of actinfilin(KLHL17) and mayven(KLHL2) , these are kelch domains.

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