title: ARHGAP8 is a novel member of the RHOGAP family related to ARHGAP1/CDC42GAP/p50RHOGAP: mutation and expression analyses in colorectal and breast cancers.
abstract: The RHO family of small GTPases has multiple functions, including regulation of cytoskeletal organization, cell cycle progression and cell migration, among others. The key members of this family are RHO, RAC and CDC42. Active GTP-bound RHO proteins are down-regulated by RHO GTPase-activating proteins (RHOGAPs). Herein, we describe the identification, characterization and mutational analysis of a novel RHOGAP designated as ARHGAP8, which is located within a critical region of loss-of-heterozygosity on chromosome 22q13.31 in breast and colorectal carcinomas. ARHGAP8 shares an identical genomic organization with ARHGAP1/CDC42GAP/p50RHOGAP and the corresponding proteins share the same functional domains that distinguish them from other ARHGAP members. These domains include the C-terminal RHOGAP domain, a central SH3-binding motif, and an N-terminal BNIP-2/CDC42GAP homology (BCH)/Sec14p-like domain. Three alternatively spliced ARHGAP8 transcripts were expressed in normal mammary gland and colon, which differed in the size of the BCH/Sec14p-like domain only. PCR-SSCP analyses revealed a total of six germline missense variants in individuals with colorectal or breast cancer; however, somatic mutations were not identified. Surprisingly, ARHGAP8 expression was up-regulated in the majority of primary colorectal tumors analyzed. Taken together, ARHGAP8 encodes a novel RHOGAP with unique functional domains that is highly homologous to ARHGAP1/CDC42GAP/p50RHOGAP.
authors.affiliation: Gastroenterology Division, Department of Medicine, University of Pennsylvania, Philadellphia, PA 19104, USA.
authors.forename: Cameron N
authors.initials: CN
authors.lastname: Johnstone
authors.forename: Sergi
authors.initials: S
authors.lastname: Castellví-Bel
authors.forename: Laura M
authors.initials: LM
authors.lastname: Chang
authors.forename: Xavier
authors.initials: X
authors.lastname: Bessa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Hideki
authors.initials: H
authors.lastname: Harada
authors.forename: Raphael K
authors.initials: RK
authors.lastname: Sung
authors.forename: Josep M
authors.initials: JM
authors.lastname: Piqué
authors.forename: Antoni
authors.initials: A
authors.lastname: Castells
authors.forename: Anil K
authors.initials: AK
authors.lastname: Rustgi
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D005091:Exons; D005260:Female; D020690:GTPase-Activating Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D005796:Genes / Q000235:genetics; D006801:Humans; D007438:Introns; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D041681:NIH 3T3 Cells; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D020764:cdc42 GTP-Binding Protein / Q000235:genetics; D018909:src Homology Domains / Q000235:genetics
chemical_list: C479829:ARHGAP8 protein, human; D020690:GTPase-Activating Proteins; C085379:rho GTPase-activating protein; D020764:cdc42 GTP-Binding Protein