CHANGES IN ACTIN CONTENT DURING INDUCED MYELOID MATURATION OF HUMAN PROMYELOCYTES

  • 1 January 1983
    • journal article
    • research article
    • Vol. 62  (2) , 308-314
Abstract
Actin is an important cytoskeletal protein; new actin synthesis occurs during differentiation of many motile cells. To better understand the process of myeloid maturation, the change in actin content during induced maturation of HL-60 human promyelocytic leukemia cells was studied. HL-60 cells induced toward myeloid maturation by a 5-day exposure to dimethylformamide showed an 86% increase in a 43,000 MW protein comigrating with rabbit muscle actin on dodecyl sulfate polyacrylamide gels. To further demonstrate that this was an increase in actin content, the total actin content lysed HL-60 cells was measured by the ability of actin to inhibit DNase I. Using this assay, actin content of HL-60 cells increased 96% during induced differentiation. The amount of incorporation of 3H-leucine into actin doubled after a 5-day exposure to dimethylformamide, suggesting the increase in actin was due primarily to new synthesis. Total new protein synthesis increased 2- to 7-fold during differentiation. Additional analysis of polyacrylamide gels showed increased quantities and new synthesis of a high MW protein comigrating with rabbit muscle myosin. Actin content apparently increases during myeloid maturation. The HL-60 cell line apparently is a useful model to study, both functional and biochemical events during human myeloid differentiation.