HeLa cells cultured in a biotin-deficient medium show reduced rate of protein synthesis, DNA synthesis and growth. Addition of exogenous biotin to the cells cultured in biotin-deficient medium results in enhanced protein synthesis, DNA synthesis and cell growth. Continuous protein synthesis is required for the increase in DNA synthesis observed upon the addition of exogenous biotin to the cells cultured in biotin-deficient medium. These results suggest that cells cultured in biotin-deficient medium are arrested in the GI stage of cell cycle and this block is removed upon the addition of biotin to the deficient medium.
Earlier work has indicated that a supplement of biotin was not required for the growth of cells in culture (Eagle, 1955;Holmes, 1959; Dupree et al., 1962). However, a requirement for biotin was shown for some cell lines grown in chemically defined media using cell growth as the only criteria (Higuchi and Robinson, 1973;Pienskowska and Koziorowska, 1975). Previously we have used viability, biotin content and activities of biotindependent and -independent enzymes to demonstrate a biotin requirement for HeLa cells, human fibroblasts, and baby hamster kidney (BHK) cells (Dakshinamurti and Chalifour, 1981;Chalifour and Dakshinamurti, 1982). Studies with biotin-deficient rats have shown a stimulatory role for biotin in RNA synthesis (Boeckx and Dakshinamurti, 1975), protein synthesis (Boeckx and Dakshinamurti, 1974) and the enhancement of guanylate cyclase activity Wesley, 1982). We have examined here the effect of addition of biotin to biotindeficient cultures on growth, protein and DNA synthesis in HeLa cells.