Growth hormone stimulates tyrosine phosphorylation of focal adhesion kinase (p125(FAK)) and actin stress fiber formation in human osteoblast-like cells, Saos2.
Bone is one of the essential target tissues of growth hormone (GH). In bone remodeling, cell-matrix attachment is important where focal adhesion kinase (FAK) is involved. FAK plays a central role in determining the shape and motility of cells in response to the extracellular matrix stimuli. In the present study, we have demonstrated that GH stimulated tyrosine phosphorylation of FAK in human osteoblast-like cells, Saos2. Moreover, GH rapidly enhanced the formation of actin stress fibers. In Saos2, Jak2 was tyrosine phosphorylated by GH stimulation, and AG490, a Jak2 specific inhibitor, inhibited GH-induced tyrosine phosphorylation of FAK and actin stress fiber reorganization. These results suggest that GH activates FAK via Jak2, and stimulates the formation of actin stress fibers in Saos2. Activation of FAK and actin stress fiber formation induced by GH seem to be important for the physiological role of osteoblast.
Takahashi
M O
MO
Third Division, Department of Medicine, Kobe University School of Medicine, Kobe, 650-0017, Japan.
Takahashi
Y
Y
Iida
K
K
Okimura
Y
Y
Kaji
H
H
Abe
H
H
Chihara
K
K
D000199:Actins / Q000096:biosynthesis*; D016723:Bone Remodeling / Q000187:drug effects / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002460:Cell Line; D015638:Cytochalasin D / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D053614:Janus Kinase 2; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*; D020032:Tyrphostins / Q000494:pharmacology
D000199:Actins; D015815:Cell Adhesion Molecules; D011518:Proto-Oncogene Proteins; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D019382:Human Growth Hormone; D015638:Cytochalasin D; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; C496050:PTK2 protein, human