TC-PTP directly interacts with connexin43 to regulate gap junction intercellular communication.
Protein kinases have long been reported to regulate connexins; however, little is known about the involvement of phosphatases in the modulation of intercellular communication through gap junctions and the subsequent downstream effects on cellular processes. Here, we identify an interaction between the T-cell protein tyrosine phosphatase (TC-PTP, officially known as PTPN2) and the carboxyl terminus of connexin43 (Cx43, officially known as GJA1). Two cell lines, normal rat kidney (NRK) cells endogenously expressing Cx43 and an NRK-derived cell line expressing v-Src with temperature-sensitive activity, were used to demonstrate that EGF and v-Src stimulation, respectively, induced TC-PTP to colocalize with Cx43 at the plasma membrane. Cell biology experiments using phospho-specific antibodies and biophysical assays demonstrated that the interaction is direct and that TC-PTP dephosphorylates Cx43 residues Y247 and Y265, but does not affect v-Src. Transfection of TC-PTP also indirectly led to the dephosphorylation of Cx43 S368, by inactivating PKCα and PKCδ, with no effect on the phosphorylation of S279 and S282 (MAPK-dependent phosphorylation sites). Dephosphorylation maintained Cx43 gap junctions at the plaque and partially reversed the channel closure caused by v-Src-mediated phosphorylation of Cx43. Understanding dephosphorylation, along with the well-documented roles of Cx43 phosphorylation, might eventually lead to methods to modulate the regulation of gap junction channels, with potential benefits for human health.
Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Hanjun
H
Li
Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Gaelle
G
Spagnol
Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Naava
N
Naslavsky
Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Steve
S
Caplan
Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA psorgen@unmc.edu.
Paul L
PL
Sorgen
D000818:Animals; D002450:Cell Communication; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism; D017629:Gap Junctions / Q000502:physiology; D016391:Genes, src / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000378:metabolism; D021381:Protein Transport; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2 / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology*; D019076:Transgenes / Q000235:genetics
D018031:Connexin 43; D004815:Epidermal Growth Factor; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; C516654:Ptpn2 protein, rat
Connexin43; Gap junctions; Phosphorylation; TC-PTP; Tyrosine phosphatase; v-Src