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Hyperosmolality in recombinant Chinese hamster ovary (rCHO) cell cultures induces autophagy and apoptosis. To investigate the effect of Bcl-x(L) overexpression on autophagy and apoptosis in hyperosmotic rCHO cell cultures, an erythropoietin (EPO)-producing rCHO cell line with regulated Bcl-x(L) 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(L) overexpression suppressed apoptosis, as evidenced by a decreased amount of cleaved caspase-7 and PARP. Concurrently, Bcl-x(L) 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(L) overexpression. In the fed-batch culture, the simultaneous application of Bcl-x(L) overexpression and nutrient feeding increased the culture longevity and maximum EPO concentration. Taken together, Bcl-x(L) overexpression delayed autophagy and apoptosis in hyperosmotic rCHO cell cultures, resulting in increased EPO production., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Upon nutrient depletion during recombinant Chinese hamster ovary (rCHO) cell batch culture, cells are subjected to apoptosis, type I programmed cell death (PCD), and autophagy which can be type II PCD or a cell survival mechanism. To investigate the effect of nutrient supplementation on the two PCDs and protein production in rCHO cells, an antibody-producing rCHO cell line was cultivated in batch and fed-batch modes. The feed medium containing glucose, amino acids, and vitamins was determined through flask culture tests and used in bioreactor cultures. In the bioreactor cultures, the nutrient feedings extended the culture longevity and enhanced antibody production. In addition, cells in the fed-batch culture showed delayed onset of both apoptosis and autophagy, compared with those in the batch culture. The inhibition of apoptosis was demonstrated by a decreased amount of cleaved caspase-7 protein and less fragmentation of chromosomal DNA. Concurrently, reduced LC3 conversion, from LC3-I to LC3-II, was observed in cells that received the feeds. Cultivation with pharmacological autophagy inducer (rapamycin) or inhibitor (bafilomycin A1) indicated that autophagy is necessary for the cells to survive under nutrient depletion. Taken together, the delayed and relieved cell death by nutrient supplementation could improve antibody production., (Copyright © 2011 Wiley Periodicals, Inc.)

Previous studies indicate that in the elderly, a morphological change in the small intestine is accompanied by apoptosis. However, currently little information is available on the molecular events leading up to the apoptotic process in aged ileum. Our current study assessed mitochondrial apoptotic signaling along with key factors known to be involved in mitochondrial permeabilization in rat ileum. Experimentations were carried out utilizing Sprague-Dawley rats at 6 and 24 months of age. The histological analysis showed a significant loss in thickness of the intestinal mucosa during aging, which was accompanied by higher reactive species. Molecular analysis revealed the mitochondrial translocation of Bax showed a significant increase with aging. However, the expression of cyclophilin D, adenine nucleotide translocator, and the voltage-dependent anion channel that regulates the mitochondria permeability transition pore decreased or remained unchanged. Furthermore, the expression of caspase 3 was enhanced in aged ileum with increased DNA fragmentation, while nuclear translocation of apoptosis-inducing factor and endonuclease G were decreased with aging. In conclusion, our findings indicate that the mitochondrial translocation of Bax by increased oxidative stress may result in cell death through caspase-dependent apoptosis in aged ileum, thereby leading to a decrease in intestinal mucosal thickness during aging., (Copyright © 2010 Elsevier Inc. All rights reserved.)

During recombinant Chinese hamster ovary (rCHO) cell culture, various events, such as feeding with concentrated nutrient solutions or the addition of base to maintain an optimal pH, increase the osmolality of the medium. To determine the effect of hyperosmotic stress on two types of programmed cell death (PCD), apoptosis and autophagy, of rCHO cells, two rCHO cell lines, producing antibody and erythropoietin, were subjected to hyperosmotic stress resulting from NaCl addition (310-610 mOsm/kg). For both rCHO cell lines, hyperosmolality up to 610 mOsm/kg increased cleaved forms of PARP, caspase-3, caspase-7, and fragmentation of chromosomal DNA, confirming the previous observation that apoptosis was induced by hyperosmotic stress. Concurrently, hyperosmolality increased the level of accumulation of LC3-II, a widely used autophagic marker, which was determined by Western blot analysis and confocal microscopy. When glucose and glutamine concentrations were measured during the cultures, glucose and glutamine concentrations in the culture medium at various osmolalities (310-610 mOsm/kg) showed no significant differences. This result suggests that induction of PCD by hyperosmotic stress occurred independently of nutrient depletion. Taken together, autophagy as well as apoptosis was observed in rCHO cells subjected to hyperosmolality., ((c) 2009 Wiley Periodicals, Inc.)