Alterations in activities of protein phosphatases PP1 and PP2A in T and B lymphocytes of autoimmune MRL/MpJ-lpr/lpr mice.
Activities of protein phosphatases PP1 and PP2A were determined in T and B lymphocytes of autoimmune-prone MRL/MpJ-lpr/lpr mice (MRL/lpr mice) and two control strains, MRL/MpJ-(+)/+ mice (MRL/+/+ mice) and C3H/HeJ mice. Potential PP1 activity, which was measured after treatment of cell extract with Co(2+)-trypsin, was much higher in T lymphocytes than B lymphocytes. However, no difference in the activity was observed between MRL/lpr mice and the controls. Spontaneous PP2A activity showed similar levels in T and B lymphocytes from normal mice, but potential PP2A activity, which was measured after treatment with 2-mercaptoethanol, was significantly higher in T lymphocytes from MRL/lpr mice than those from controls. No differences were detected in PP1 or PP2A activities in B lymphocytes. From these results, our previous data [Matsuzawa, S. et al. (1992) J. Biochem. 111, 472-477] demonstrating increases in potential activities of PP1 and PP2A in lymphoid tissues from autoimmune MRL/lpr mice can be interpreted as follows. 1) The increase in potential PP1 activity of the lymphoid tissues from MRL/lpr mice is caused by replacement of B lymphocytes by abnormal T lymphocytes, which accumulate in enormous numbers. 2) The increase of potential PP2A activity in the lymphoid tissues from MRL/lpr mice is caused by the increase in this activity in their T lymphocytes.
Zhu
T
T
Section of Biochemistry, Hokkaido University.
Matsuzawa
S
S
Mizuno
Y
Y
Kikuchi
K
K
D000818:Animals; D001327:Autoimmune Diseases / Q000201:enzymology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D004988:Ethers, Cyclic / Q000494:pharmacology; D051379:Mice; D008809:Mice, Inbred C3H; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D000097847:Protein Phosphatase Inhibitory Proteins
D004988:Ethers, Cyclic; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases; D011506:Proteins; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins