Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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The hallmark neuropathology of Huntington's disease (HD) is due to elongation of a polyglutamine segment in huntingtin, a novel approximately 350 kDa protein of unknown function. We used a yeast two-hybrid interactor screen to identify proteins whose association with huntingtin might be altered in the pathogenic process. Surprisingly, no interactors were found with internal and C-terminal segments of huntingtin. In contrast, huntingtin's N-terminus detected 13 distinct proteins, seven novel and six reported previously. Among these, we identified a major interactor class, comprising three distinct WW domain proteins, HYPA, HYPB and HYPC, that bind normal and mutant huntingtin in extracts of HD lymphoblastoid cells. This interaction is mediated by huntingtin's proline-rich region and is enhanced by lengthening the adjacent glutamine tract. Although HYPB and HYPC are novel, HYPA is human FBP-11, a protein implicated in spliceosome function. The emergence of this class of proteins as huntingtin partners argues that a WW domain-mediated process, such as non-receptor signaling, protein degradation or pre-mRNA splicing, may participate in HD pathogenesis.
Hum Mol Genet 1998 Sep
PMID:Huntingtin interacts with a family of WW domain proteins. 970 Feb 2

An elongated glutamine tract in mutant huntingtin initiates Huntington's disease (HD) pathogenesis via a novel structural property that displays neuronal selectivity, glutamine progressivity and dominance over the normal protein based on genetic criteria. As this mechanism is likely to involve a deleterious protein interaction, we have assessed the major class of huntingtin interactors comprising three WW domain proteins. These are revealed to be related spliceosome proteins (HYPA/FBP-11 and HYPC) and a transcription factor (HYPB) that implicate huntingtin in mRNA biogenesis. In HD post-mortem brain, specific antibody reagents detect each partner in HD target neurons, in association with disease-related N-terminal morphologic deposits but not with filter trapped insoluble-aggregate. Glutathione S:-transferase partner 'pull-down' assays reveal soluble, aberrantly migrating, forms of full-length mutant huntingtin specific to HD target tissue. Importantly, these novel mutant species exhibit exaggerated WW domain binding that abrogates partner association with other huntingtin isoforms. Thus, each WW domain partner's association with huntingtin fulfills HD genetic criteria, supporting a direct role in pathogenesis. Our findings indicate that modification of mutant huntingtin in target neurons may promote an abnormal interaction with one, or all, of huntingtin's WW domain partners, perhaps altering ribonucleoprotein function with toxic consequences.
Hum Mol Genet 2000 Sep 01
PMID:Huntingtin's WW domain partners in Huntington's disease post-mortem brain fulfill genetic criteria for direct involvement in Huntington's disease pathogenesis. 1095 56

FMNL1, FMNL2, FMNL3, DAAM1, DAAM2, DIAPH1 and DIAPH2 constitute the Formin-homology subfamily with FDD, FH1 and FH2 domains. FMNL2 gene is linked to FNBP3 (also known as HYPA) gene on human chromosome 2q23.3, while FMNL3 gene to FNBP3L (also known as HYPC) gene on 12q13. Because human FNBP3 cDNA (NM_017892.2) was a 5'-truncated partial clone, we identified and characterized human FNBP3 gene by using bioinformatics. Human FNBP3 gene, consisting of 26 exons, was located within human genome sequences AC079344.5, AC012443.8, and human chromosome 2 genomic contig NT_005403.13. Nucleotide sequence of human FNBP3 cDNA was determined in silico by assembling nucleotide sequences of 26 exons of FNBP3 gene. HYPA cDNA and IMAGE cDNA clones 3356968, 4026200, 4733897 were 3'-truncated partial FNBP3 cDNAs, while FNBP3 (NM_017892.2), FLJ11559, NY-REN-6, and FLJ20585 were 5'-truncated partial FNBP3 cDNAs. Two FNBP3 isoforms with or without 126-bp region in the 3'-part of exon 1 were transcribed due to alternative splicing. FNBP3 isoform 2 without the 126-bp region was the major FNBP3 transcript. Two WW domains, two FF domains, two bipartite nuclear localization signals, FB3HM and FB3HC domains were conserved among vertebrate FNBP3 homologs, including human FNBP3, FNBP3L, mouse Fnbp3, Fnbp3l, chicken fnbp3 and zebrafish fnbp3. FNBP3, binding to TNFSF6 (Fas ligand), Huntingtin and Formin proteins, might transduce extracellular signals to the Rho-related signaling pathway. On the other hand, FNBP3 with nuclear localization signals and two tyrosine phosphorylation sites might transduce extracellular signals to the nucleus. This is the first report on comprehensive characterization of human FNBP3 gene.
Int J Mol Med 2003 Oct
PMID:Identification and characterization of human FNBP3 gene in silico. 1296 49

Rett syndrome is a dominant neurological disorder caused by loss-of-function mutations of methyl-CpG-binding protein 2 (MeCP2). MeCP2 is an abundant chromatin-associated protein that contains two well characterized domains. Through an N-terminal domain it recognizes methyl-CpGs and binds to nonmethylated DNA. A domain in the middle of the protein can act as a transcriptional repressor in transient transfection studies. The C-terminal region of the protein is equally essential for the function of MeCP2, as documented by recurrently found frameshift mutations. However, little is known about its functional role. Here we mapped a domain within MeCP2 capable of binding specifically to Group II WW domains of splicing factors formin-binding protein (FBP) 11 and HYPC. Binding was assessed by glutathione S-transferase pull-down assays and coimmunoprecipitation assays. The Group II WW domain binding region was localized from residue 325 to the C-terminus, with the interacting proline-rich sequence at its center. We then used comparison with genotype-phenotype studies in Rett syndrome patients to evaluate the relevance of Group II WW domain interactions of MeCP2 for pathogenesis. Truncation of the WW domain binding region by 48 C-terminal amino acids (to residue 438), causing Rett syndrome, resulted in reduced or loss of WW domain binding activity. Truncation to residue 400, representing a large group of frameshift mutations accounting for approx. 10% of Rett syndrome cases, abolished WW domain binding activity completely. On the other hand, two benign missense mutations did not affect binding. Furthermore, a short C-terminal truncation and an internal deletion, both causing mild to moderate mental retardation in males, were associated with weak or loss of WW domain binding activity.
J Mol Med (Berl) 2004 Feb
PMID:A WW domain binding region in methyl-CpG-binding protein MeCP2: impact on Rett syndrome. 1461 41