Expression of serum response factor (SRF) in normal and regenerating pancreas

Abstract Background: SRF is a transcription factor that controls mesodermal differentiation. To date, there has been no report demonstrating the role of SRF in endodermally derived tissue. Genetic ablation of SRF results in embryonic lethality precluding analysis of SRF in pancreatic development. We sought to determine the expression of SRF in the normal adult rodent pancreas and during pancreatic regeneration (PR). Methods: Pancreata from adult rodents were harvested and fixed in 4% paraformaldehyde. Sections were stained for SRF expression using a polyclonal antibody. 90% pancreatectomies were performed and regenerating pancreatic remnants harvested at 0, 24, 72 hrs and 7 days. Tissues were processed and stained as above. Sham laparotomies served as controls. Results: Nuclear staining for SRF was observed in normal pancreatic ductal, acinar, and islet cells. Staining was stronger in islet cells compared to ductal and acinar cells. Double staining for insulin demonstrated islet SRF staining was predominately within the beta cells. During PR, SRF expression was increased with maximal expression at 36 hours (Fig 1B) . Download : Download high-res image (74KB) Download : Download full-size image Fig 1A . Sham acinar cells (36 hrs) no AC staining. Fig 1B: PR acinar cells (36hrs) SRF AC staining (arrow). SRF expression continued to be increased compared to baseline and sham at 7 days. In contrast to normal pancreata, SRF expression in the regenerating pancreas was found predominately in the acinar cytoplasm (AC). Conclusion: For the first time, SRF expression is observed in all three cellular components of the pancreas. During PR, SRF expression is increased and redistributed to the acinar cytoplasm. The data suggests SRF may be an important regulator of pancreatic growth, replication, and differentiation.