The T-cell protein tyrosine phosphatase is phosphorylated on Ser-304 by cyclin-dependent protein kinases in mitosis.
Two alternatively spliced forms of the human protein tyrosine phosphatase TCPTP (T-cell protein tyrosine phosphatase) exist: a 48 kDa form that is targeted to the endoplasmic reticulum (TC48) and a shorter 45 kDa form that is targeted to the nucleus (TC45). In this study we have identified Ser-304 (Phe301-Asp-His-Ser304-Pro-Asn-Lys307) as a major TCPTP phosphory-lation site and demonstrate that TC45, but not TC48, is phosphorylated on this site in vivo. Phosphorylation of TC45 on Ser-304 was cell cycle-dependent, and increased as cells progressed from G2 into mitosis, but subsided upon mitotic exit. Ser-304 phosphorylation was increased when cells were arrested in mitosis by microtubule poisons such as nocodazole, but remained unaltered when cells were arrested at the G2/M checkpoint by adriamycin. Phosphorylation of Ser-304 did not alter significantly the phosphatase activity or the protein stability of TC45, and had no apparent effect on TC45 localization. Ser-304 phosphorylation was ablated when cells were treated with the CDK (cyclin-dependent protein kinase) inhibitors roscovitine or SU9516, but remained unaltered when ERK1/2 activation was inhibited with the MEK (mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase) inhibitor PD98059. In addition, recombinant CDKs, but not the Polo-like kinase Plk1, phosphorylated Ser-304 in vitro. Our studies identify Ser-304 as a major phosphorylation site in human TCPTP, and the TC45 variant as a novel mitotic CDK substrate.
Bukczynska
Patricia
P
Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria 3800, Australia.
Klingler-Hoffmann
Manuela
M
Mitchelhill
Kenneth I
KI
Lam
Mark H C
MH
Ciccomancini
Melissa
M
Tonks
Nicholas K
NK
Sarcevic
Boris
B
Kemp
Bruce E
BE
Tiganis
Tony
T
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D019556:COS Cells / Q000201:enzymology; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D006367:HeLa Cells / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000201:enzymology; D008938:Mitosis / Q000502:physiology*; D008970:Molecular Weight; D010766:Phosphorylation; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D014162:Transfection / Q000379:methods
D007527:Isoenzymes; D012694:Serine; D018844:Cyclin-Dependent Kinases; C516649:PTPN2 protein, human; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D017027:Protein Tyrosine Phosphatases