Coincident expression of menkes gene with copper efflux in human
placental cells.
Qian, Yongchang, Sudeep Majumdar, M. C. M. Reddy, and Edward D.
Harris.
Department of Biochemistry and Biophysics, Texas A&M University,
College Station, TX 77843-2128
APStracts 3:0089C, 1996.
BeWo cells, a human choriocarcinoma cell line, have a high-affinity
system for transporting copper ions into the cell (K[mu]=0.21 [mu]M),
but are sluggish in releasing copper back into the medium from
preloaded cells. The slow efflux rate has recently been shown to
correlate with a failure of BeWo cells to express the Menkes
transcript (Qian et al., in press). We have now determined that only
when BeWo cells were grown on plastic surfaces such as petri dishes
or flasks did they display negligible release and enhanced retention
of 67Cu. RT-PCR using primers selective for the Menkes gene failed to
show any evidence of a Menkes transcript in cells cultured on plastic
surfaces. In contrast, cells grown on porous filters previously shown
to allow apical and basolateral surfaces to develop did display the
transcript and showed significant copper release with normal
retention. Release of copper from filter-grown cells was blocked with
p-chloromercuribenzoate (PCMB), thus confirming sulfhydryl group
involvement. Absorption of the 67Cu either as a free ion or bound to
ceruloplasmin was unaffected by the different culture conditions. The
data link the Menkes gene product with the ability of cells to
release copper ions. They also suggest the expression of the Menkes
gene may be regulated by the development of polarized cell membranes.
Received 11 January 1996; accepted in final form 13 March 1996.
APS Manuscript Number C13-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96