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Effects of NHE1 Expression Level on CHO Cell Responses to Environmental Stress
Author(s) -
Abston Lisa R.,
Miller William M.
Publication year - 2008
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp049680q
Subject(s) - intracellular ph , osmole , chemistry , ammonia , lactic acid , intracellular , osmotic concentration , homeostasis , osmotic shock , biochemistry , cell culture , chinese hamster ovary cell , cell , sodium–hydrogen antiporter , cell growth , sodium , biology , microbiology and biotechnology , endocrinology , gene , bacteria , genetics , receptor , organic chemistry
Ammonia, lactate and CO 2 inhibit animal cell growth. Accumulation of these metabolic byproducts also causes a decrease in intracellular pH (pH i ). Transport systems regulate pH i in eukaryotic cells. Ion transporters have been cloned and overexpressed in cells but have not been examined for protection against the buildup of ammonia, lactate or CO 2 . The Na + /H + exchangers (NHE) transport H + ions from cells during acidification to increase pH i . We examined whether overexpression of NHE1 would provide CHO cells with greater protection from elevated ammonia, lactate or CO 2 . NHE1 CHO cells were compared to MT2–1‐8 (“normal” levels of NHE) and AP‐1 (devoid of any NHE activity) CHO cell lines. Expression of at least “normal” levels of NHE1 is necessary for CHO cell survival during exposure to 30 mM lactic acid without pH adjustment or to 20 mM NH 4 Cl with pH adjustment. Resistance to an acute acid‐load increased when NHE1 was overexpressed in CHO cells. Surprisingly, the inhibitory effect on cell growth at 195 mmHg pCO 2 /435 mOsm/kg (normal levels are 40 mmHg pCO 2 /320 mOsm/kg) was not affected by the NHE1 level. Also, there was no further decrease in CHO cell growth in the absence of NHE1 expression during elevated osmolality alone (up to 575 mOsm/kg).