N. Conran et Fw. Hemming, Phorbol ester induces a transient increase in alpha(5)beta(1)-mediated adhesion of the megakaryoblastic cell line CHRF 288-11, PLATELETS, 10(2-3), 1999, pp. 117-123
This study investigated the mechanism by which treatment of the CHRF 288-11
megakaryoblastic cell line with phorbol myristate acetate caused a transie
nt increase in adhesion, The adhesion to tissue culture plastic occurred wi
thin 4 h and could be reversed by treatment with RGDS-peptide suggesting th
e involvement of one or more RGD-binding integrins, Ligand-binding adhesion
assays suggested that PMA-induced CHRF 288-11 cells had very little affini
ty for fibrinogen, a low affinity for vitronectin and a much higher affinit
y for fibronectin. Further adhesion assays performed in the presence of var
ious integrin antagonists or inhibiting monoclonal antibodies demonstrated
that the fibronectin-mediated cell adhesion is via the alpha(5)beta(1), fib
ronectin receptor, integrin, Flow cytometrical investigations showed that t
his increase in alpha(5)beta(1)-adhesion on CHRF 288-11 cells following PMA
stimulation was not brought about by an increase in alpha(5)beta(1)-integr
in expression and inferred that increased adhesion is achieved by an increa
se in alpha(5)beta(1) ligand-binding function. These findings confirm other
reports using different cells that the expression and function of integrin
s may play an important role in megakaryocytopoiesis. Modulation of integri
n function may facilitate the migration of maturing megakaryoblasts in the
bone marrow stroma before their movement through the sinus wall and into th
e blood stream. The report demonstrates that the CHRF 288-11 megakaryoblast
ic cell line is a useful model for investigating some aspects of these phen
omena.