Epidermal growth factor-mediated transient phosphorylation and membrane localization of myosin II-B are required for efficient chemotaxis.
Epidermal growth factor (EGF) stimulation of prostate metastatic tumor cells results in transient phosphorylation and cellular localization of non-muscle myosin heavy chain II-B (NMHC II-B) with kinetics similar to those seen in chemotaxis. We demonstrate that expression of 18- and 72-kDa fragments derived from the NMHC II-B C terminus that contain EGF-dependent NMHC II-B phosphorylation sites serve as dominant-negative mutations for EGF-dependent NMHC II-B phosphorylation and localization. Both fragments inhibited the EGF-dependent phosphorylation by competing with NMHC II-B on the myosin heavy chain kinase. However, only expression of the 72-kDa fragment resulted in cells with abnormalities in cell shape, focal adhesions, and chemotaxis. We found that the 72-kDa (but not 18-kDa) fragment is capable of self-assembly. To our knowledge, these results provide the first strong evidence that EGF-dependent NMHC II-B phosphorylation is required for the cellular localization of NMHC II-B and that NMHC II-B is required for normal cell attachment and for chemotactic response.
Ben-Ya'acov
Ami
A
Department of Biochemistry, Institute of Medical Sciences, Hadassah Medical School, Hebrew University, Jerusalem 91120, Israel.
Ravid
Shoshana
S
D001693:Biological Transport, Active / Q000187:drug effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D048429:Cell Size; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D022001:Focal Adhesions / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D024501:Nonmuscle Myosin Type IIB / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000473:pathology / Q000503:physiopathology; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D024501:Nonmuscle Myosin Type IIB