title: Identification of the GTPase-activating protein DEP domain containing 1B (DEPDC1B) as a transcriptional target of Pitx2.
abstract: Pitx2 is a bicoid-related homeobox transcription factor implicated in regulating left-right patterning and organogenesis. However, only a limited number of Pitx2 downstream target genes have been identified and characterized. Here we demonstrate that Pitx2 is a transcriptional repressor of DEP domain containing 1B (DEPDC1B). The first intron of the human and mouse DEP domain containing 1B genes contains multiple consensus DNA-binding sites for Pitx2. Chromatin immunoprecipitation assays revealed that Pitx2, along with histone deacetylase 1, was recruited to the first intron of Depdc1b. In contrast, RNAi-mediated depletion of Pitx2 not only enhanced the acetylation of histone H4 in the first intron of Depdc1b, but also increased the protein level of Depdc1b. Luciferase reporter assays also showed that Pitx2 could repress the transcriptional activity mediated by the first intron of human DEPDC1B. The GAP domain of DEPDC1B interacted with nucleotide-bound forms of RAC1 in vitro. In addition, exogenous expression of DEPDC1B suppressed RAC1 activation and interfered with actin polymerization induced by the guanine nucleotide exchange factor TRIO. Moreover, DEPDC1B interacted with various signaling molecules such as U2af2, Erh, and Salm. We propose that Pitx2-mediated repression of Depdc1b expression contributes to the regulation of multiple molecular pathways, such as Rho GTPase signaling.
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States.
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.affiliation: Experimental and Clinical Research Center (ECRC), a Cooperation between Max Delbrück Center and Charité Universitätsmedizin Berlin, Campus Buch, Berlin, Germany.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States.
authors.forename: Kevin
authors.initials: K
authors.lastname: Jimenez-Cowell
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Mold
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Sollecito
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Lombana
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States.
authors.forename: Meng
authors.initials: M
authors.lastname: Jiao
authors.affiliation: Department of Biological Sciences, Fordham University, Bronx, NY 10458, United States. Electronic address: qwei3@fordham.edu.
authors.forename: Qize
authors.initials: Q
authors.lastname: Wei
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004789:Enzyme Activation; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000502:physiology*; D006801:Humans; D051379:Mice; D041681:NIH 3T3 Cells; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D000097577:Homeobox Protein PITX2
chemical_list: D020690:GTPase-Activating Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; D020830:rac1 GTP-Binding Protein; D000097577:Homeobox Protein PITX2; C000598579:DEPDC1B protein, human; C107953:RAC1 protein, human
keywords: DEPDC1B; GTPase signaling; Pitx2; Transcriptional regulation