The phosphorylation of CapZ-interacting protein (CapZIP) by stress-activated protein kinases triggers its dissociation from CapZ.
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.
Eyers
Claire E
CE
MRC Protein Phosphorylation Unit, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, UK.
McNeill
Helen
H
Knebel
Axel
A
Morrice
Nick
N
Arthur
Simon J C
SJ
Cuenda
Ana
A
Cohen
Philip
P
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D051347:CapZ Actin Capping Protein / Q000378:metabolism*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019169:Jurkat Cells; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013154:Spleen / Q000378:metabolism; D013379:Substrate Specificity
D000199:Actins; D051347:CapZ Actin Capping Protein; D047908:Intracellular Signaling Peptides and Proteins; C506059:RCSD1 protein, human; D010768:Phosphoserine; D020928:Mitogen-Activated Protein Kinases