Retinoic acid induction of nuclear envelope-limited chromatin sheets in HL-60.
Exposure of the human leukemic cell line (HL-60) to 1 microM retinoic acid (RA) induces in vitro granulopoiesis, including the development of lobulated nuclei. Ultrastructural studies, presented here, demonstrate the formation of extensive quantities of nuclear envelope-limited chromatin sheets (ELCS), in addition to nuclear lobulation, following treatment with RA. ELCS contain DNA, as shown by the Feulgen-like electron microscope stain osmium ammine-B. Lamin B was demonstrated in ELCS by immunoelectron microscopy with colloidal gold-labeled antibody. Formation of ELCS occurred in Bcl2-overexpressing HL-60 cell sublines with suppressed apoptotic cell death, indicating separable mechanisms for ELCS formation and apoptosis. Immunofluorescent and immunoblotting procedures demonstrated modulations in the amounts and distribution of nuclear envelope-associated components. Total amounts of lamins A/C and cytoplasmic vimentin were reduced by RA treatment. The amounts of lamin B, lamin B receptor (LBR), and lamina-associated polypeptide 2 (LAP2) did not exhibit significant quantitative changes, but acquired heterogeneous staining patterns on the nuclear envelope. RA induced the appearance of low-molecular-weight LBR-related proteins. This study demonstrated the parallel induction of lobulated nuclei and of ELCS and the modulation of nuclear envelope components following exposure of HL-60 to retinoic acid.
Olins
A L
AL
Foundation for Blood Research, 69 US Route One, Scarborough, Maine, 04070-0190, USA.
Buendia
B
B
Herrmann
H
H
Lichter
P
P
Olins
D E
DE
D017209:Apoptosis; D002843:Chromatin / Q000187:drug effects* / Q000648:ultrastructure; D018922:HL-60 Cells; D006801:Humans; D015151:Immunoblotting; D008934:Mitogens / Q000494:pharmacology*; D009685:Nuclear Envelope / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*
D002843:Chromatin; D008934:Mitogens; D009687:Nuclear Proteins; D014212:Tretinoin