Abstract:

Objective To explore the effects of cAMP response element binding protein (CREB) signaling pathway on the protection of podocytes by the protein kinase A (PKA). Methods The 14-25 generations of mouse podocytes 5P12 differentiated under constant condition were selected and divided into the control group, adriamycin (ADR) treatment group (ADR group), and PKA specific agonist (pCPT-cAMP) pre-culture+ADR stimulation group (pCPT-cAMP+ADR group). Cell toxicity was detected by CCK-8 method. The expression of cleaved caspase-3 in podocytes was detected by Western blotting. The expression of CREB in podocytes was inhibited by siRNA and the localization and expression of phosphorylated CREB (p-CREB) were detected by immunofluorescence confocal microscopy and Western blotting. Results ADR induced up-regulation of the expression of cleaved caspase-3 in podocytes and pre-culture by pCPT-cAMP could significantly decrease the elevated expression of cleaved caspase-3 induced by ADR. ADR decreased the number of podocytes to (40.45±6.78)% of its original number and pre-culture by pCPT-cAMP increased the number of podocytes to (69.8±5.48)% of its original number. Results of Western blotting showed that pre-culture by pCPT-cAMP for 5 and 15 min could increase the expressions of p-CREB in total protein of podocytes by (105.64±38.21)% and (98.61±41.03)% and those in nuclei by (114.52±11.28)% and (118.84±14.44)%. Immunofluorescence confocal microscopy showed that pCPT-cAMP mainly increased the expression of p-CREB in nuclei. siRNA could decreased the protein expression of CREB in podocytes to (25.1±2.44)% of its original expression and pre-culture by pCPT-cAMP could not prevent the ADR-induced up-regulation of the expression of cleaved caspase-3. Conclusion Transcription factor CREB mediates the protective effect of PKA signaling pathway on podocytes.

Key words: podocyte, cyclic adenosine monophosphate, protein kinase A, cAMP response element binding protein, apoptosis