To characterize the consequences of the LMNA mutation at the

We chose the well established insulin producing MAPK 機能 b cell lines, MIN6 and INS 1, as an experimental model sys tem to test this hypothesis. Here, we show that survivin is regulated by several pancreatic b cell growth factors, including glucose, insulin, and EGF. Induction of survi vin by EGF occurs extremely quickly, within 15 minutes of treatment. The mechanism of EGF induced survivin occurs primarily through activation of the ERK pathway and prolongation of survivin half life by inhibiting ubi quitin conjugation on the survivin protein. Thus, we have identified a novel mechanism for survivin regula tion in pancreatic b cells that implicates ERK as a criti cal molecule for its post translational modification and signaling for protein degradation.<br><br> Results EGF regulates survivin protein expression in pancreatic b cells To begin to understand the mitogenic responsiveness of survivin in pancreatic b cells we made use of the immorta lized mouse and rat b cell lines, MIN6 and INS 1. MIN6 cells were cultured under proliferating MK-1775 臨床試験 conditions then serum and glucose deprived for 2 to 4 hours, prior to treatment for 30 minutes with glucose or insulin. Results showed that varying concentrations of glucose or insulin added to the cells can induce survivin protein expression at these early time points. MIN6 cells treated with glucose had a 10 fold increase in survivin protein levels at a concentration of 5. 5 mM, Cells treated with insulin at a concen tration of 20 nM had a similar increase in survivin levels, As IGF 1 and EGF are both known to stimulate survivin in cancer cells, we next tested whether these growth factors can also induce survivin in pancreatic b cells.<br><br> MIN6 and INS 1 cells were serum deprived over night then treated with IGF 1 or EGF for serial time points, EGF treated cells showed a five to ten fold increase in survivin protein levels within 15 to 30 minutes after treatment, with no differences observed following IGF 1 treatment, These early increases in protein expression suggested ms-275 構造 that EGF likely regulates molecular mechanisms that modify survivin protein stability, rather than its transcription or translation. As survivin is a multifunctional protein whose diverse activities are carried out in different subcellular com partments, we next sought to gain insight into the potential effects of EGF on survivin localization.<br><br> To this end, we performed indirect immunofluorescence stain ing using a survivin antibody in the presence or absence of EGF, to visualize the endogenous survivin protein within INS 1 cells, along with cell fractionation to quan tify survivin expression within these compartments. Sur vivin localized to both nuclear and cytoplasmic compartments of untreated and EGF treated cells, as observed by indirect immunofluorescence, An increase in both nuclear and cytoplasmic survivin protein was observed by cell fractionation following EGF treatment, These results suggest that EGF stimulates both the anti apoptotic and pro mitotic func tions of survivin in pancreatic b cells.