Cloning and characterization of a cdc25 phosphatase from mouse lymphocytes.
Members of the cdc25 phosphatase family are proposed to function as important regulators of the eukaryotic cell cycle, particularly in the induction of mitotic events. A new cdc25 tyrosine phosphatase, cdc25M1, has been cloned from a mouse pre-B cell cDNA library and characterized. The cdc25M1 protein consists of 465 amino acids with a predicted relative molecular mass (M(r)) of 51,750. Over the highly conserved carboxyl terminal region, the amino acid sequence similarity to the human cdc25 C or Hs1 isoform is 89%, while the overall similarity is 67%. The phosphatase active site is located within residues 367-374. Tissue expression of the cdc25M1 was highest in mouse spleen and thymus by northern blot analysis. The cdc25M1 mRNA was detected in a number of cloned mouse lymphocyte cell lines including both CD8+ and CD4+ cells. cdc25M1 mRNA was shown to be cell cycle-regulated in T cells following interleukin-2 (IL-2)-stimulation. Accumulation of cdc25M1 mRNA occurred at 48 h after IL-2 stimulation, when lymphocytes were progressing from S phase to G2/M phase of the cell cycle. This pattern of expression is in contrast to that observed for other protein tyrosine phosphatases expressed in T lymphocytes including CD45, LRP, SHP, and PEP. The elevation in cdc25M1 mRNA level occurred concomittant to the appearance of the hyperphosphorylated form of p34cdc2 protein kinase. A purified, bacterial-expressed recombinant cdc25M1 phosphatase domain catalyzed the dephosphorylation of p-nitrophenol phosphate, as well as [32P-Tyr] and [32P-Ser/Thr]-containing substrates. Preincubation of p34cdc2 kinase with cdc25M1 activated its histone H1 kinase activity in vitro. These results suggest that cdc25M1 may be involved in regulating the proliferation of mouse T lymphocytes following cytokine stimulation, through its action on p34cdc2 kinase.
Nargi
J L
JL
Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110.
Woodford-Thomas
T A
TA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016203:CDC2 Protein Kinase / Q000032:analysis; D002453:Cell Cycle; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D007376:Interleukin-2 / Q000494:pharmacology; D008214:Lymphocytes / Q000201:enzymology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D020687:cdc25 Phosphatases
D018076:DNA, Complementary; D007376:Interleukin-2; D011506:Proteins; D012333:RNA, Messenger; D016203:CDC2 Protein Kinase; D017027:Protein Tyrosine Phosphatases; D020687:cdc25 Phosphatases