TY - JOUR
T1 - Calcium effects on epidermal growth factor receptor‐mediated endocytosis in normal and SV40‐transformed human fibroblasts
AU - Tupper, Joseph T.
AU - Bodine, Peter V.
PY - 1983/5
Y1 - 1983/5
N2 - Lowering of extracellular Ca2+ levels will reversibly arrest the growth of human fibroblasts (WI38). Simian virus40(SV40)‐transformed WI38 cells do not exhibit this Ca2+‐dependent arrest. One possibility for this difference in Ca2+ requirement is that extracellular or surface membrane‐bound Ca2+ may be required for growth factor receptor‐mediated endocytosis and this Ca2+ requirement may differ in normal versus transformed cells. In this study we have evaluated the role of Ca2+ in the binding, internalization, and degradation of epidermal growth factor (EGF) in the WI38 and SV40 WI38 cell. The binding of [125I]EGF to the cell surface is not significantly altered by lowering of Ca2+ to 10−5‐M levels in either the normal or transformed cell. At this Ca2+ level, growth of the normal cell is inhibited. The subsequent internalization of EGF is reduced nearly threefold in the normal cell but not in the transformed cell following Ca2+ deprivation. Degradation of the EGF‐receptor complex is also sensitive to Ca2+. A twofold reduction in the rate of release of acid‐soluble 125I occurs in the normal but not the transformed cell under conditions of lowered medium Ca2+. In contrast, 2‐chloro‐10‐3‐aminopropyl phenothiazine (CP), an inhibitor of the Ca2+‐dependent regulator protein calmodulin, causes an inhibition of [125I]EGF internalization and degradation in both the normal and transformed WI38 cell, and a marked inhibition of [125I]EGF binding to the cell surface receptor of the transformed cell but not the normal cell.
AB - Lowering of extracellular Ca2+ levels will reversibly arrest the growth of human fibroblasts (WI38). Simian virus40(SV40)‐transformed WI38 cells do not exhibit this Ca2+‐dependent arrest. One possibility for this difference in Ca2+ requirement is that extracellular or surface membrane‐bound Ca2+ may be required for growth factor receptor‐mediated endocytosis and this Ca2+ requirement may differ in normal versus transformed cells. In this study we have evaluated the role of Ca2+ in the binding, internalization, and degradation of epidermal growth factor (EGF) in the WI38 and SV40 WI38 cell. The binding of [125I]EGF to the cell surface is not significantly altered by lowering of Ca2+ to 10−5‐M levels in either the normal or transformed cell. At this Ca2+ level, growth of the normal cell is inhibited. The subsequent internalization of EGF is reduced nearly threefold in the normal cell but not in the transformed cell following Ca2+ deprivation. Degradation of the EGF‐receptor complex is also sensitive to Ca2+. A twofold reduction in the rate of release of acid‐soluble 125I occurs in the normal but not the transformed cell under conditions of lowered medium Ca2+. In contrast, 2‐chloro‐10‐3‐aminopropyl phenothiazine (CP), an inhibitor of the Ca2+‐dependent regulator protein calmodulin, causes an inhibition of [125I]EGF internalization and degradation in both the normal and transformed WI38 cell, and a marked inhibition of [125I]EGF binding to the cell surface receptor of the transformed cell but not the normal cell.
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U2 - 10.1002/jcp.1041150209
DO - 10.1002/jcp.1041150209
M3 - Article
C2 - 6302104
AN - SCOPUS:0020646358
SN - 0021-9541
VL - 115
SP - 159
EP - 166
JO - Journal of Cellular Physiology
JF - Journal of Cellular Physiology
IS - 2
ER -