title: Proteomic analysis reveals CCT is a target of Fragile X mental retardation protein regulation in Drosophila.
abstract: Fragile X mental retardation protein (FMRP) is an RNA-binding protein that is required for the translational regulation of specific target mRNAs. Loss of FMRP causes Fragile X syndrome (FXS), the most common form of inherited mental retardation in humans. Understanding the basis for FXS has been limited because few in vivo targets of FMRP have been identified and mechanisms for how FMRP regulates physiological targets are unclear. We have previously demonstrated that Drosophila FMRP (dFMRP) is required in early embryos for cleavage furrow formation. In an effort to identify new targets of dFMRP-dependent regulation and new effectors of cleavage furrow formation, we used two-dimensional difference gel electrophoresis and mass spectrometry to identify proteins that are misexpressed in dfmr1 mutant embryos. Of the 28 proteins identified, we have identified three subunits of the Chaperonin containing TCP-1 (CCT) complex as new direct targets of dFMRP-dependent regulation. Furthermore, we found that the septin Peanut, a known effector of cleavage, is a likely conserved substrate of fly CCT and is mislocalized in both cct and in dfmr1 mutant embryos. Based on these results we propose that dFMRP-dependent regulation of CCT subunits is required for cleavage furrow formation and that at least one of its substrates is affected in dfmr1- embryos suggesting that dFMRP-dependent regulation of CCT contributes to the cleavage furrow formation phenotype.
authors.affiliation: Institute of Cellular and Molecular Biology and Section of Molecular Cell and Developmental Biology, University of Texas at Austin, 2400 Speedway Ave, Patterson Labs 216, Austin, TX 78712, USA. monzokf@mail.nih.gov
authors.forename: Kate
authors.initials: K
authors.lastname: Monzo
authors.forename: Susan R
authors.initials: SR
authors.lastname: Dowd
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Minden
authors.forename: John C
authors.initials: JC
authors.lastname: Sisson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D036703:Blastula / Q000196:embryology; D056404:Chaperonin Containing TCP-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics / Q000378:metabolism*; D005600:Fragile X Syndrome / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009154:Mutation; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics; D040901:Proteomics / Q000379:methods; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D056404:Chaperonin Containing TCP-1; D029721:Drosophila Proteins; D051860:Fragile X Messenger Ribonucleoprotein 1; D021122:Protein Subunits; C467328:FMR1 protein, Drosophila