Association of tyrosine phosphatase SHP-2 with F-actin at low cell densities.
SHP-2 is an intracellular SH2 domain-containing protein-tyrosine phosphatase with an essential role in cell signaling. Here we demonstrate that localization of SHP-2 is regulated by cell density in a cell adhesion-dependent manner. When cells were plated at low densities, SHP-2 was distributed in Triton X-100-insoluble fractions, whereas it was totally soluble when cells were plated at high densities or when low density cells approached confluency. In all cases, the total protein level of SHP-2 was not changed. Fluorescent cell staining revealed that SHP-2 was co-localized with actin stress fibers to the cell peripheral at low cell densities but was diffused in the entire cytoplasm at high cell densities. Transient transfection of cells with truncated forms of SHP-2 demonstrated that the catalytic domain of the enzyme was responsible for the density-regulated distribution of SHP-2, but the catalytic activity was not required. An in vitro co-sedimentation study demonstrated direct binding of full-length and SH2 domain-truncated forms of SHP-2 to F-actin. The data indicate that SHP-2 is regulated by cell density and that it may have a role in assembling and disassembling of the actin network.
Xu
F
F
Department of Medicine/Hematology-Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6305, USA.
Zhao
R
R
Peng
Y
Y
Guerrah
A
A
Zhao
Z J
ZJ
D016475:3T3 Cells; D000199:Actins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002452:Cell Count; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D017830:Octoxynol; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D012995:Solubility; D014162:Transfection; D014407:Tumor Cells, Cultured
D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D017830:Octoxynol; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases