title: Active Mek2 as a regulatory scaffold that promotes Pin1 binding to BPGAP1 to suppress BPGAP1-induced acute Erk activation and cell migration.
abstract: BPGAP1 is a multidomain Rho GTPase-activating protein (RhoGAP) that promotes Erk activation and cell motility. However, the molecular mechanism of how these two processes are linked and regulated remains unclear. Here, we show that the RhoGAP domain of BPGAP1 interacts with the peptidyl-prolyl cis/trans isomerase (PPI) Pin1, leading to enhanced GAP activity towards RhoA. BPGAP1 also interacted with wild-type and constitutively active Mek2, but not with its kinase-dead mutant. However, only active Mek2 could bind Pin1, acting as a scaffold to bridge Pin1 and BPGAP1 in a manner that involves the release of an autoinhibited proline-rich motif, 186-PPLP-189, proximal to the RhoGAP domain. This allows the non-canonical 186-PPLP-189 and 256-DDYGD-260 motifs of the proline-rich region and RhoGAP domain of BPGAP1 to become accessible to concerted binding by the WW and PPI domains of Pin1, respectively. Interestingly, Pin1 knockdown led to 'super-induction' of BPGAP1-induced acute, but not chronic, Erk activation upon epidermal growth factor stimulation, in a process independent of GAP modulation. Reintroducing Pin1, but not its catalytic or non-binding mutants, reversed the effect and inhibited cell migration induced by coexpression of BPGAP1 and active Mek2. Thus, Pin1 regulates BPGAP1 function in Rho and Erk signalling, with active Mek2 serving as a novel regulatory scaffold that promotes crosstalk between RhoGAP, Pin1 and Erk in the regulation of cell migration.
authors.affiliation: Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.
authors.forename: Catherine Qiurong
authors.initials: CQ
authors.lastname: Pan
authors.forename: Yih-Cherng
authors.initials: YC
authors.lastname: Liou
authors.forename: Boon Chuan
authors.initials: BC
authors.lastname: Low
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002465:Cell Movement; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D048370:MAP Kinase Kinase 2 / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D055232:Proline-Rich Protein Domains; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: C479829:ARHGAP8 protein, human; D020690:GTPase-Activating Proteins; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D048049:Extracellular Signal-Regulated MAP Kinases; D048370:MAP Kinase Kinase 2; C482129:Map2k2 protein, mouse; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse