[Effect of insulin-like growth factor-I on apoptosis in Chinese hamster ovary cells for biopharmaceutical production]

The ability to reducing death due to apoptosis and maintaining extensive levels on cell viability under serum free media in cell culture are important subjects in production of recombinant proteins. Insulin-like growth factor-I [IGF-I], is the growth factor of choice for mammalian cell proliferation in serum-free culture. In addition to its mitogenic activity, it has antiapoptotic activity protecting cultures from diverse death inducing stimuli. In this study, the effect of different concentrations of IGF-I examined on CHO-K1 [Chinese hamster ovary K1 cells] cell line for 24 and 48 hours. In this experimental study, the cell line was cultivated in DMEM supplemented with 10% fetal bovine serum [FBS]. Apoptosis process was induced in cells by methotrexate, serum was removed and then 10-50 ng/ml concentrations of IGF-I were added. Apoptosis was assessed by caspase 3 detection kit and cell proliferation and viability determined by MTT assay. Caspase 3 activity decreased significantly by increasing concentrations of IGF-I. In the highest concentration of IGF-I [50 ng/ml], 1.7 and 1.4 equal decreases of caspase 3 activities, compared with negative control group, were noted after 24 and 48 hours, respectively. It confirmed antiapoptotic activity of growth factor to maintain viability and protect cultures from apoptotic inducing stimuli [methotrexate]. IGF-I, as antiapoptotic factor, decreased programmed death of CHO-K1 cells in apoptotic induced conditions

comparative study on the chaperone-like activity of camel and bovine beta -caseins

Molecular chaperones are characterized by a general behavior, arresting the exposed hydrophobic surfaces of denaturing substrate proteins. In the present study, the capacity of beta -caseins [beta -CN] from camel and bovine milk in suppression of thermal aggregation process of apo-yeast alcohol dehydrogenase [YADH] was assessed. Apo-I enzyme was prepared by removal of the structural zinc; while apo-II-protein was obtained by depleting conformational and catalytic zinc atoms. Fluorescence spectroscopy using ANS probe revealed greater hydrophobic surface in apo-II ADH. Considerable decrease in aggregation of the heat treated protein molecules was observed upon exposing to beta -CNs [camel, bovine]. Bovine beta -CN afforded more adverse effects on thermal aggregation. A direct correlation between casein's chaperone activity and structural stability of the substrate proteins was displayed. Moreover, an association between casein source and chaperone-like activity is suggested