초록
<P><B>Highlights</B></P><P>► Hyperosmolality in CHO cell cultures induces autophagy and apoptosis. ► Bcl-x<SUB>L</SUB> overexpression delays autophagy/apoptosis in hyperosmotic CHO cell cultures. ► Bcl-x<SUB>L</SUB> overexpression improves cell viability and EPO production at hyperosmolality.</P> <P><B>Abstract</B></P><P>Hyperosmolality in recombinant Chinese hamster ovary (rCHO) cell cultures induces autophagy and apoptosis. To investigate the effect of Bcl-x<SUB>L</SUB> overexpression on autophagy and apoptosis in hyperosmotic rCHO cell cultures, an erythropoietin (EPO)-producing rCHO cell line with regulated Bcl-x<SUB>L</SUB> overexpression was subjected to hyperosmolality resulting from NaCl addition in a batch culture and nutrient supplementation in a fed-batch culture. In the batch culture, Bcl-x<SUB>L</SUB> overexpression suppressed apoptosis, as evidenced by a decreased amount of cleaved caspase-7 and PARP. Concurrently, Bcl-x<SUB>L</SUB> overexpression also delayed autophagy, as indicated by reduced LC3 conversion, from LC3-I to LC3-II. As a result, the cell viability and EPO production were improved by Bcl-x<SUB>L</SUB> overexpression. In the fed-batch culture, the simultaneous application of Bcl-x<SUB>L</SUB> overexpression and nutrient feeding increased the culture longevity and maximum EPO concentration. Taken together, Bcl-x<SUB>L</SUB> overexpression delayed autophagy and apoptosis in hyperosmotic rCHO cell cultures, resulting in increased EPO production.</P>