Paulson J R, Ciesielski W A, Schram B R, Mesner P W
Department of Chemistry, University of Wisconsin-Oshkosh 54901.
J Cell Sci. 1994 Jan;107 ( Pt 1):267-73. doi: 10.1242/jcs.107.1.267.
It is shown here that treatment of metaphase-arrested HeLa cells with okadaic acid (0.15-2.5 microM) leads to dephosphorylation of histone H1. This effect is presumably due to the specific ability of okadaic acid to inhibit protein phosphatases 1 and/or 2A, because okadaic acid tetraacetate, which is not a phosphatase inhibitor, has no effect. Dephosphorylation of H1 does not occur if okadaic acid-treated cells are simultaneously treated with 20 nM calyculin A, or if the okadaic acid concentration is 5.0 microM or greater. The mechanism behind this phenomenon is not known. However, the results suggest that the chain of events leading to histone dephosphorylation may be negatively controlled by a protein phosphatase 2A, while the phosphatase which actually dephosphorylates H1 could be a protein phosphatase 1. It remains to be determined whether the phosphatase involved here is the same enzyme as that which dephosphorylates H1 at the end of normal mitosis.
本文表明，用冈田酸（0.15 - 2.5微摩尔）处理中期停滞的HeLa细胞会导致组蛋白H1去磷酸化。这种效应可能是由于冈田酸具有抑制蛋白磷酸酶1和/或2A的特定能力，因为非磷酸酶抑制剂的冈田酸四乙酸酯没有这种作用。如果用冈田酸处理的细胞同时用20纳摩尔的花萼海绵诱癌素A处理，或者冈田酸浓度为5.0微摩尔或更高时，H1的去磷酸化就不会发生。这种现象背后的机制尚不清楚。然而，结果表明，导致组蛋白去磷酸化的一系列事件可能受到蛋白磷酸酶2A的负调控，而实际使H1去磷酸化的磷酸酶可能是蛋白磷酸酶1。这里涉及的磷酸酶是否与正常有丝分裂末期使H1去磷酸化的酶相同，仍有待确定。
