title: Changes in actin and actin-binding proteins during the differentiation of HL-60 leukemia cells.
abstract: Actin and actin-binding proteins form a peripheral network on the cytosolic side of the plasma membrane. These cytoskeleton proteins are involved in functions that require cellular movement and may also have a role in modulating signal transduction during cellular proliferation and differentiation. To measure changes in F-actin and actin-binding proteins during HL-60 differentiation, cells were induced to mature along the granulocytic pathway by exposure to 1 microM retinoic acid (RA) for 5 days and were analyzed for F-actin and actin-binding proteins by flow cytometry. The amounts of F-actin and spectrin in untreated HL-60 cells and in those undergoing differentiation by treatment with the retinoid did not differ. N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)-phallacidin was used to measure F-actin content and a monoclonal antibody followed by fluorescence isothiocyanate-conjugated goat anti-mouse immunoglobulin antibody was used to measure the content of spectrin; cells were analyzed by flow cytometry. In contrast, cells exposed to RA contained larger amounts of alpha-actinin, vinculin, talin, lipocortin I, and lipocortin II, as determined with their respective antibodies followed by flow cytometric analysis as described above. An RA-supersensitive clone of HL-60, designated HL-60/S4, exhibited lower constitutive levels of alpha-actinin, vinculin, and talin but a higher constitutive level of lipocortin II than parental cells. Treatment of HL-60/S4 with RA led to increases in vinculin, talin, lipocortin I, and lipocortin II. An RA-resistant clone, designated HL-60/R3, constitutively expressed larger amounts of alpha-actinin, vinculin, lipocortin I, and lipocortin II than parental HL-60 cells. Treatment of HL-60/R3 with RA resulted in decreases in the amounts of these actin-binding proteins. Changes in actin-binding proteins that occur during the differentiation of HL-60 cells suggest that these proteins may be of importance to the expression of the mature phenotype.
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
authors.forename: M F
authors.initials: MF
authors.lastname: Leung
authors.forename: T S
authors.initials: TS
authors.lastname: Lin
authors.forename: A C
authors.initials: AC
authors.lastname: Sartorelli
mesh_terms: D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D017302:Annexins; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D006801:Humans; D007136:Immunoglobulins; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D008840:Microfilament Proteins / Q000378:metabolism*; D013049:Spectrin / Q000378:metabolism; D016608:Talin / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D016596:Vinculin / Q000032:analysis
chemical_list: D000199:Actins; D017302:Annexins; D002135:Calcium-Binding Proteins; D007136:Immunoglobulins; D008840:Microfilament Proteins; D016608:Talin; D000185:Actinin; D016596:Vinculin; D013049:Spectrin; D014212:Tretinoin