PTP-PEST controls EphA3 activation and ephrin-induced cytoskeletal remodelling

Abstract

Eph receptors and their corresponding membrane-bound ephrin ligands regulate cell positioning and establish tissue patterns during embryonic and oncogenic development. Emerging evidence suggests that assembly of polymeric Eph signalling clusters relies on cytoskeletal reorganisation and underlies regulation by protein tyrosine phosphatases (PTPs). PTP-PEST (also known as PTPN12) is a central regulator of actin cytoskeletal dynamics. Here, we demonstrate that an N-terminal fragment of PTP-PEST, generated through an ephrinA5-triggered and spatially confined cleavage mediated by caspase-3, attenuates EphA3 receptor activation and its internalisation. Isolation of EphA3 receptor signalling clusters within intact plasma membrane fragments obtained by detergent-free cell fractionation reveals that stimulation of cells with ephrin triggers effective recruitment of this catalytically active truncated form of PTP-PEST together with key cytoskeletal and focal adhesion proteins. Importantly, modulation of actin polymerisation using pharmacological and dominant-negative approaches affects EphA3 phosphorylation in a similar manner to overexpression of PTP-PEST. We conclude that PTP-PEST regulates EphA3 activation both by affecting cytoskeletal remodelling and through its direct action as a PTP controlling EphA3 phosphorylation, indicating its multifaceted regulation of Eph signalling.

CD99–PTPN12 Axis Suppresses Actin Cytoskeleton-Mediated Dimerization of Epidermal Growth Factor Receptor

“…One novel finding of this study is that the CD99–PTPN12 axis participates in the regulation of ligand-induced activation of EGFR by suppressing the reorganization of the actin cytoskeleton. This observation is consistent with a previous study, which demonstrated that PTPN12 controls EphA3 activation by regulating actin cytoskeletal organization during Eph clustering [ 8 ]. Furthermore, we previously reported the molecular mechanism by which CD99 induces β1 integrin inactivation via PTPN12 activation [ 24 ].…”

“…As described above, PTPN12 acts as a negative regulator of multiple RTKs implicated in tumor progression [ 8 , 13 , 15 , 39 ]. We hypothesized that PTPN12 may restrain the activation of several cytoplasmic adaptor and kinase proteins that are recruited to EGFR following ligand binding, resulting in attenuation of the activated intracellular signals.…”

“…It is certain that PTPN12 is involved in regulating cellular motility and morphology, since the phosphatase acts as a central regulator of actin cytoskeleton reorganization [ 8 , 9 , 40 ]. We performed co-immunoprecipitation to further verify the effects of CD99CRIII3-activated PTPN12 on Rac1/RhoA GTPase signaling pathways.…”

“…Non-receptor type 12 protein tyrosine phosphatase (PTPN12) acts as a core regulator in actin cytoskeleton-mediated modulation of growth factor receptor dynamics [ 8 ]. PTPN12 controls Rho GTPase activity by suppressing the interaction of p120 catenin with guanine nucleotide exchange factor VAV2 [ 9 , 10 , 11 , 12 ].…”

Phosphoproteomics identifies a bimodal EPHA2 receptor switch that promotes embryonic stem cell differentiation

“…We also provide evidence that EPHA2 activation supports pluripotency gene expression by inhibiting ERK1/2 28,29 . EPHA2 has been shown to recruit protein tyrosine phosphatases 34,[49][50][51] , and we show that EPHA2 activation drives recruitment of the protein tyrosine phosphatase SHP2/PTPN11. As SHP2 is a key scaffold for ERK1/2 activation, EPHA2 may sequester SHP2 from key FGF-dependent phosphotyrosine sites that are required for ERK1/2 signalling.…”