Human diploid fibroblast-like cells (CF-3) as a model system for the study of Golgi biogenesis

Human diploid fibroblast-like cells were maintained in an arrested, essentially non-mitotic state for extended periods of time in culture by lowering the serum concentration in the medium from 10 to 0.5%. These arrested cells re-entered the proliferative state when subcultivated in medium containing 10% serum. The morphological distribution and enzymic activities associated with the Golgi complex were examined during growth, arrest, and recovery. Cells grown in medium containing 10% serum possessed a well-developed Golgi complex consisting of parallel arrays of membranes and associated vesicles. Galactosyl transferase activity was highest after 3 days growth (17.5 ± 5.0 nmol galactose transferred/45 min/mg protein) and declined to 9.8 ± 3.0 at day 7. When the serum concentration was reduced to 0.5%, Golgi complexes were rarely observed by electron microscopy and galactosyl transferase activity was further reduced to 4.6 ± 1.2 and 3.2 ± 1.4 after 3- and 7-day arrests, respectively. Arrested cells subcultured into medium containing 10% serum recovered from the arrested state and ultrastructurally resembled cells continuously cultured at the higher serum level. Numerous Golgi complexes reappeared and galactosyl transferase activity increased to 13.0 ± 3.34 days after subcultivation. These results indicate that the Golgi complex can be experimentally mainipulated in human diploid fibroblast-like cells in a manner which may be useful for the study of the biogenesis of this organelle.