A fragment of alpha-actinin promotes monocyte/macrophage maturation in vitro.
Conditioned media (CM) from cultures of HL-60 myeloid leukemia cells grown on extracellular bone marrow matrix contains a factor that induces macrophage-like maturation of HL-60 cells. This factor was purified from the CM of HL-60 cells grown on bone marrow stroma by ammonium sulfate precipitation, then sequential chromatography on DEAE, affi-gel blue affinity, gel exclusion, and wheat germ affinity columns, followed by C-4 reverse phase HPLC, and SDS-PAGE. The maturation promoting activity of the CM was identified in a single 31 kD protein. Amino acid sequence analysis of four internal tryptic peptides of this protein confirmed significant homology with amino acid residues 48-60, 138-147, 215-220, and 221-236 of human cytoskeletal alpha-actinin. An immunoaffinity purified rabbit polyclonal anti-chicken alpha-actinin inhibited the activity of HL-60 conditioned media. A 27 kD amino-terminal fragment of alpha-actinin produced by thermolysin digestion of chicken gizzard alpha-actinin, but not intact alpha-actinin, had maturation promoting activity on several cell types, including blood monocytes, as measured by lysozyme secretion and tartrate-resistant acid phosphatase staining. We conclude that an extracellular alpha-actinin fragment can promote monocyte/macrophage maturation. This represents the first example of a fragment of a cytoskeletal component, which may be released during tissue remodeling and repair, playing a role in phagocyte maturation.
Veterans Affairs Medical Center, Department of Medicine, University of Minnesota, Minneapolis 55417, USA.
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Luikart
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Wahl
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Hinkel
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Masri
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Oegema
D000185:Actinin / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D017077:Culture Media, Conditioned; D018922:HL-60 Cells; D006801:Humans; D008264:Macrophages / Q000166:cytology*; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology*; D010446:Peptide Fragments / Q000235:genetics / Q000494:pharmacology*; D011817:Rabbits
D017077:Culture Media, Conditioned; D010446:Peptide Fragments; D000185:Actinin