Eyers Claire E, McNeill Helen, Knebel Axel, Morrice Nick, Arthur Simon J C, Cuenda Ana, Cohen Philip
MRC Protein Phosphorylation Unit, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Biochem J. 2005 Jul 1;389(Pt 1):127-35. doi: 10.1042/BJ20050387.
A protein expressed in immune cells and muscle was detected in muscle extracts as a substrate for several SAPKs (stress-activated protein kinases). It interacted specifically with the F-actin capping protein CapZ in splenocytes, and was therefore termed 'CapZIP' (CapZ-interacting protein). Human CapZIP was phosphorylated at Ser-179 and Ser-244 by MAPKAP-K2 (mitogen-activated protein kinase-activated protein kinase 2) or MAPKAP-K3 in vitro. Anisomycin induced the phosphorylation of CapZIP at Ser-179 in Jurkat cells, which was prevented by SB 203580, consistent with phosphorylation by MAPKAP-K2 and/or MAPKAP-K3. However, osmotic shock-induced phosphorylation of Ser-179 was unaffected by SB 203580. These and other results suggest that CapZIP is phosphorylated at Ser-179 in cells by MAPKAP-K2/MAPKAP-K3, and at least one other protein kinase. Stress-activated MAP kinase family members phosphorylated human CapZIP at many sites, including Ser-68, Ser-83, Ser-108 and Ser-216. Ser-108 became phosphorylated when Jurkat cells were exposed to osmotic shock, which was unaffected by SB 203580 and/or PD 184352, or in splenocytes from mice that do not express either SAPK3/p38gamma or SAPK4/p38delta. Our results suggest that CapZIP may be phosphorylated by JNK (c-Jun N-terminal kinase), which phosphorylates CapZIP to >5 mol/mol within minutes in vitro. Osmotic shock or anisomycin triggered the dissociation of CapZIP from CapZ in Jurkat cells, suggesting that phosphorylation of CapZIP may regulate the ability of CapZ to remodel actin filament assembly in vivo.
在肌肉提取物中检测到一种在免疫细胞和肌肉中表达的蛋白质，它是几种应激激活蛋白激酶（SAPK）的底物。它在脾细胞中与F-肌动蛋白封端蛋白CapZ特异性相互作用，因此被称为“CapZIP”（CapZ相互作用蛋白）。人CapZIP在体外被丝裂原活化蛋白激酶激活的蛋白激酶2（MAPKAP-K2）或MAPKAP-K3在丝氨酸179和丝氨酸244处磷酸化。茴香霉素诱导Jurkat细胞中CapZIP在丝氨酸179处磷酸化，SB 203580可阻止这种磷酸化，这与MAPKAP-K2和/或MAPKAP-K3的磷酸化一致。然而，渗透休克诱导的丝氨酸179磷酸化不受SB 203580影响。这些及其他结果表明，CapZIP在细胞中丝氨酸179处被MAPKAP-K2/MAPKAP-K3以及至少一种其他蛋白激酶磷酸化。应激激活的丝裂原活化蛋白激酶家族成员在多个位点使人CapZIP磷酸化，包括丝氨酸68、丝氨酸83、丝氨酸108和丝氨酸216。当Jurkat细胞受到渗透休克时，丝氨酸108发生磷酸化，这不受SB 203580和/或PD 184352影响，或者在不表达SAPK3/p38γ或SAPK4/p38δ的小鼠脾细胞中也会发生。我们的结果表明，CapZIP可能被JNK（c-Jun氨基末端激酶）磷酸化，JNK在体外几分钟内可使CapZIP磷酸化至>5摩尔/摩尔。渗透休克或茴香霉素触发Jurkat细胞中CapZIP与CapZ解离，这表明CapZIP的磷酸化可能在体内调节CapZ重塑肌动蛋白丝组装的能力。
