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A high level of cell surface phosphatidylinositol-specific phospholipase C activity is characteristic of growth-arrested 3T3 fibroblasts but not of transformed variants.
J Cell Physiol. 1992 Jun; 151(3):613-22.JC

Abstract

Confluent monolayers of four contact-inhibited mouse fibroblast lines (Swiss 3T3, Balb/c 3T3, NIH 3T3, and C3H10T1/2) were found to have substantial levels of a cell surface phosphatidylinositol-specific phospholipase C (ecto-PLC). In contrast, confluent cultures of virally, chemically, or spontaneously transformed variants derived from these cell lines expressed undetectable or negligible levels of this enzyme activity. A simple and rapid assay, using lysophosphatidylinositol radio-labeled in the inositol group ([3H]-lysoPI) as the substrate was developed to provide a quantitative measure of the phospholipase C activity present at the external cell surface. For cells testing positive for ecto-PLC activity, rapid uptake of [3H]-lysoPI is accompanied by the simultaneous appearance of [3H]-inositol phosphate in the external medium. Confluent monolayers of the four mouse fibroblast lines exhibiting density-dependent growth inhibition had levels of ecto-PLC activity in the range of 50-800 pmol/min/10(6) cells (i.e., about 20-50 times greater than the activity observed for the transformed variants). The expression of ecto-PLC activity at the cell surface of the Swiss or Balb/c cells was dependent on the state of cell proliferation. Cultures which had become quiescent through attainment of confluence displayed a tenfold increased activity over that of subconfluent, growing cultures of these cells. Similarly, subconfluent Swiss 3T3 cells which had become quiescent following exposure to low serum conditions also showed increased activity. These results indicate that there may exist a correlation between the control of cell proliferation in contact-inhibited mouse fibroblasts and the expression of inositol phospholipid-specific phospholipase C activity at the external cell surface.

Authors+Show Affiliations

Institute of Molecular Biology, University of Oregon, Eugene 97403.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

1338336

Citation

Volwerk, J J., et al. "A High Level of Cell Surface Phosphatidylinositol-specific Phospholipase C Activity Is Characteristic of Growth-arrested 3T3 Fibroblasts but Not of Transformed Variants." Journal of Cellular Physiology, vol. 151, no. 3, 1992, pp. 613-22.
Volwerk JJ, Birrell GB, Hedberg KK, et al. A high level of cell surface phosphatidylinositol-specific phospholipase C activity is characteristic of growth-arrested 3T3 fibroblasts but not of transformed variants. J Cell Physiol. 1992;151(3):613-22.
Volwerk, J. J., Birrell, G. B., Hedberg, K. K., & Griffith, O. H. (1992). A high level of cell surface phosphatidylinositol-specific phospholipase C activity is characteristic of growth-arrested 3T3 fibroblasts but not of transformed variants. Journal of Cellular Physiology, 151(3), 613-22.
Volwerk JJ, et al. A High Level of Cell Surface Phosphatidylinositol-specific Phospholipase C Activity Is Characteristic of Growth-arrested 3T3 Fibroblasts but Not of Transformed Variants. J Cell Physiol. 1992;151(3):613-22. PubMed PMID: 1338336.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A high level of cell surface phosphatidylinositol-specific phospholipase C activity is characteristic of growth-arrested 3T3 fibroblasts but not of transformed variants. AU - Volwerk,J J, AU - Birrell,G B, AU - Hedberg,K K, AU - Griffith,O H, PY - 1992/6/1/pubmed PY - 1992/6/1/medline PY - 1992/6/1/entrez SP - 613 EP - 22 JF - Journal of cellular physiology JO - J Cell Physiol VL - 151 IS - 3 N2 - Confluent monolayers of four contact-inhibited mouse fibroblast lines (Swiss 3T3, Balb/c 3T3, NIH 3T3, and C3H10T1/2) were found to have substantial levels of a cell surface phosphatidylinositol-specific phospholipase C (ecto-PLC). In contrast, confluent cultures of virally, chemically, or spontaneously transformed variants derived from these cell lines expressed undetectable or negligible levels of this enzyme activity. A simple and rapid assay, using lysophosphatidylinositol radio-labeled in the inositol group ([3H]-lysoPI) as the substrate was developed to provide a quantitative measure of the phospholipase C activity present at the external cell surface. For cells testing positive for ecto-PLC activity, rapid uptake of [3H]-lysoPI is accompanied by the simultaneous appearance of [3H]-inositol phosphate in the external medium. Confluent monolayers of the four mouse fibroblast lines exhibiting density-dependent growth inhibition had levels of ecto-PLC activity in the range of 50-800 pmol/min/10(6) cells (i.e., about 20-50 times greater than the activity observed for the transformed variants). The expression of ecto-PLC activity at the cell surface of the Swiss or Balb/c cells was dependent on the state of cell proliferation. Cultures which had become quiescent through attainment of confluence displayed a tenfold increased activity over that of subconfluent, growing cultures of these cells. Similarly, subconfluent Swiss 3T3 cells which had become quiescent following exposure to low serum conditions also showed increased activity. These results indicate that there may exist a correlation between the control of cell proliferation in contact-inhibited mouse fibroblasts and the expression of inositol phospholipid-specific phospholipase C activity at the external cell surface. SN - 0021-9541 UR - https://www.unboundmedicine.com/medline/citation/1338336/A_high_level_of_cell_surface_phosphatidylinositol_specific_phospholipase_C_activity_is_characteristic_of_growth_arrested_3T3_fibroblasts_but_not_of_transformed_variants_ L2 - https://doi.org/10.1002/jcp.1041510322 DB - PRIME DP - Unbound Medicine ER -