A. Baz et al., SUBCELLULAR-DISTRIBUTION AND PROFILES OF PROSOMES (PROTEASOMES-MCP) DURING DIFFERENTIATION OF HUMAN LYMPHOBLASTIC CELL-LINE, Leukemia research, 21(11-12), 1997, pp. 1061-1070
The human lymphoblastoid leukemic cell line (CCRF-CEM) was induced to
differentiate with phorbol 12-myristate 13-acetate (PMA). During diffe
rentiation, assessed by monitoring the cluster of differentiation (CD)
profile, the prosome (proteasomes, multi-catalytic proteinase) distri
bution and composition were studied by microscopy, flow cytometry and
western blot analysis. Changes in prosome subunits were monitored usin
g 3 monoclonal antibodies anti-p23K, p29K and p31K. There were changes
in the subcellular distribution of prosome antigens in PMA treated ce
lls compared to untreated cells. The amount of cytoplasmic prosomal an
tigens decreased during the first three days of differentiation and th
e membrane antigens increased; meanwhile there was an increase of p53
and no change in actin protein levels. As mitotic cyclins are degraded
by the ubiquitin pathway and therefore via the prosome, the decrease
observed in differentiated cells suggests that prosomes are involved i
n the cell cycle and thus in cell proliferation. (C) 1997 Elsevier Sci
ence Ltd. All rights reserved.