Late G1 amino acid restriction point in human dermal fibroblasts

✍ Scribed by Janet L. Cooper; Walker Wharton

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 601 KB
• Volume: 124
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041240311

✦ Synopsis

Human dermal fibroblasts arrested in G0 by maintenance in medium supplemented with 0.1% serum were not restimulated to divide when fresh medium containing 10% dialyzed serum but lacking group B amino acids (cystine, isoleucine, lysine, phenylalanine and tyrosine) was added. Unlike rodent cells, the addition of fresh serum-supplemented medium lacking only isoleucine did not cause a growth arrest. The amino acid sensitive growth arrest in human fibroblasts was dependent both on presynchronization in G0 as well as a prestarvation for amino acids prior to stimulation with high serum. When cells were restimulated in the absence of amino acids, they arrested predominantly in G1, although a small percentage of cells entered early S phase. When medium containing a complete complement of amino acids was then added, cells initiated DNA synthesis following a minimum lag of 2-3 hr. Growth arrested cells initiated DNA synthesis even when complete unsupplemented medium was added, although the addition of high concentrations of insulin or 10% serum increased the rate of entry.