title: Caspase-3 regulates catalytic activity and scaffolding functions of the protein tyrosine phosphatase PEST, a novel modulator of the apoptotic response.
abstract: The protein tyrosine phosphatase PEST (PTP-PEST) is involved in the regulation of the actin cytoskeleton. Despite the emerging functions attributed to both PTPs and the actin cytoskeleton in apoptosis, the involvement of PTP-PEST in apoptotic cell death remains to be established. Using several cell-based assays, we showed that PTP-PEST participates in the regulation of apoptosis. As apoptosis progressed, a pool of PTP-PEST localized to the edge of retracting lamellipodia. Expression of PTP-PEST also sensitized cells to receptor-mediated apoptosis. Concertedly, specific degradation of PTP-PEST was observed during apoptosis. Pharmacological inhibitors, immunodepletion experiments, and in vitro cleavage assays identified caspase-3 as the primary regulator of PTP-PEST processing during apoptosis. Caspase-3 specifically cleaved PTP-PEST at the (549)DSPD motif and generated fragments, some of which displayed increased catalytic activity. Moreover, caspase-3 regulated PTP-PEST interactions with paxillin, leupaxin, Shc, and PSTPIP. PTP-PEST acted as a scaffolding molecule connecting PSTPIP to additional partners: paxillin, Shc, Csk, and activation of caspase-3 correlated with the modulation of the PTP-PEST adaptor function. In addition, cleavage of PTP-PEST facilitated cellular detachment during apoptosis. Together, our data demonstrate that PTP-PEST actively contributes to the cellular apoptotic response and reveal the importance of caspases as regulators of PTPs in apoptosis.
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang 115, Taipei, Taiwan.
authors.forename: Maxime
authors.initials: M
authors.lastname: Hallé
authors.forename: Ying-Chih
authors.initials: YC
authors.lastname: Liu
authors.forename: Serge
authors.initials: S
authors.lastname: Hardy
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Théberge
authors.forename: Christophe
authors.initials: C
authors.lastname: Blanchetot
authors.forename: Annie
authors.initials: A
authors.lastname: Bourdeau
authors.forename: Tzu-Ching
authors.initials: TC
authors.lastname: Meng
authors.forename: Michel L
authors.initials: ML
authors.lastname: Tremblay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism* / Q000494:pharmacology; D002384:Catalysis / Q000187:drug effects; D022081:Cell Surface Extensions / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013379:Substrate Specificity / Q000187:drug effects
chemical_list: D011993:Recombinant Fusion Proteins; C516738:PTPN12 protein, human; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; C516739:Ptpn12 protein, mouse; D053148:Caspase 3