PSTPIP: A Tyrosine Phosphorylated Cleavage Furrow–associated Protein that Is a Substrate for a PEST Tyrosine Phosphatase

Abstract

We have investigated proteins which interact with the PEST-type protein tyrosine phosphatase, PTP hematopoietic stem cell fraction (HSCF), using the yeast two-hybrid system. This resulted in the identification of proline, serine, threonine phosphatase interacting protein (PSTPIP), a novel member of the actin- associated protein family that is homologous to Schizosaccharomyces pombe CDC15p, a phosphorylated protein involved with the assembly of the actin ring in the cytokinetic cleavage furrow. The binding of PTP HSCF to PSTPIP was induced by a novel interaction between the putative coiled-coil region of PSTPIP and the COOH-terminal, proline-rich region of the phosphatase. PSTPIP is tyrosine phosphorylated both endogenously and in v-Src transfected COS cells, and cotransfection of dominant-negative PTP HSCF results in hyperphosphorylation of PSTPIP. This dominant-negative effect is dependent upon the inclusion of the COOH-terminal, proline-rich PSTPIP-binding region of the phosphatase. Confocal microscopy analysis of endogenous PSTPIP revealed colocalization with the cortical actin cytoskeleton, lamellipodia, and actin-rich cytokinetic cleavage furrow. Overexpression of PSTPIP in 3T3 cells resulted in the formation of extended filopodia, consistent with a role for this protein in actin reorganization. Finally, overexpression of mammalian PSTPIP in exponentially growing S. pombe results in a dominant-negative inhibition of cytokinesis. PSTPIP is therefore a novel actin-associated protein, potentially involved with cytokinesis, whose tyrosine phosphorylation is regulated by PTP HSCF.

Hippo signalling in the G2/M cell cycle phase: Lessons learned from the yeast MEN and SIN pathways

“…Any involvement of YAP and TAZ, the two established Hippo targets [27][28][29][30][31], in mitotic exit and cytokinesis has not been reported so far. Possibly Cdc14 phosphatases can be activated by Hippo signalling, which could be part of the regulation of PSTPIP1, the mammalian homolog of yeast Hof1p [121]. Taken together, by considering all these open questions, we look forward to exciting new discoveries in mammalian Hippo signalling and its role in mitotic progression.…”

TCR-induced downregulation of protein tyrosine phosphatase PEST augments secondary T cell responses

“…They all contain an N-terminal PTP domain and an extended C-terminus with several proline-rich motifs . Through one of these motifs, PTP-PEST associates with the SH3 domain of the Csk kinase (Davidson et al, 1997), through another one with the cytoskeletal scaffold protein paxillin Shen et al, 1998Shen et al, , 2000, and through the C-terminal region with PSTPIP1 (Spencer et al, 1997), and PSTPTP2 (Wu et al, 1998). All three proteins appear to be dephosphorylated by PTP-PEST and PSTPIP1 reportedly also directs PTP-PEST towards the c-Abl tyrosine kinase (Cong et al, 2000) and WASP (Badour et al, 2004;Cote et al, 2002).…”

NOSTRIN: A protein modulating nitric oxide release and subcellular distribution of endothelial nitric oxide synthase

“…Display of a single cdc15 and SH3 domain each characterize the protein as a member of the Pombe cdc15 homology (PCH) family of proteins (34), including CD2BP1 (35), PACSIN1 (36), PSTPIP (37), as well as the nonmammalian homologue CG4040. The functions of PCH proteins are not fully understood, but they have been implied with dynamic rearrangements of the cytoskeleton (34).…”