Background and Aims

Endoplasmic reticulum (ER) stress has been implicated in the loss of function and death of pancreatic β-cells in both types of diabetes. An important istep in the resolution of ER stress is the inhibition of protein synthesis. The aim of study was to determine how protein synthesis is repressed in pancreatic β-cells in response to ER stress by utilising selective translation initiation factor dependency of viral mRNAs. Such knowledge is important for a full understanding of β-cell biology in health and disease and how this might be targeted therapeutically.

Methods

48 h post-transfection the MiIN6 cells incubated for 4 h in the presence or absence of a thapsigargin(1mM).Cap-dependent and indenoedent were determined using the dual-luciferase reporter assay

Protein synthesis measured. by [³⁵S]methionine and trichloroacetic acid method .Data were analysed by two-tailed paired t-tests using GraphPad Prism .

Results

As EMCV translation occurs independently of eIF4E, and pRF (Fig 1)

As HCV translation occurs independently of eIF4E, eIF4B and eIF4A (fig2)

CrPV IRES translationis resistant to ER stress (Fig3).Thus ER stress-induced repression of protein synthesis is caused by the perturbation of an initiation factor or factors.

Treatment with thapsigargin for4,12 and 24 h inhibited protein synthesis , the PERKinhibitor restore it .(fig 4)

Conclusions

This work provides a deeper understanding into how ER stress represses protein synthesis in pancreatic β-cells which may be of importance in designing new anti-diabetogenic strategies.