Roles of Inhibitors of Poly(ADP-ribose) Polymerase in Protecting Rat RINm5F Cell Line against Free Fatty Acid-induced Apoptosis

Abstract

Background: Chronic exposure to high levels of free fatty acid (FFA) has adverse effects on the function of pancreatic beta-cell, with a consequent increase in the production of reactive oxygen species. Poly (ADP-Ribose) polymerase (PARP-1) overactivation leads to massive NAD⁺ consumption and ATP depletion with induction of cellular necrosis under high reactive oxygen species. In the present study, we investigated whether inhibitors of poly(ADP-ribose) polymerase were capable of protecting beta-cells from death induced by extended exposure to FFA.

Materials and Methods: RINm5F cell line was cultured in the presence of FFA (palmitate) in order to induce apoptosis, and then cells were treated with low-potency poly(ADP-ribose) polymerase inhibitor (3-aminobenzamide) or potent poly(ADP-ribose) polymerase inhibitor (PJ34). In order to explore whether poly(ADP-ribose) polymerase inhibitors could inhibit the apoptosis induced by FFA, expression of PARP-1 was measured by RT-qPCR and Western blot, while the apoptosis of RINm5F cells were analyzed by flow cytometry and Tdt-mediated dUTP Nick-End Labeling(TUNEL).

Results: Low-potency poly(ADP-ribose) polymerase inhibitor (3-aminobenzamide) significantly suppressed the impaired insulin secretion and FFA-induced apoptosis (P<0.01). However, potent poly(ADP-ribose) polymerase inhibitor (PJ34) had no significant effects on FFA-induced apoptosis (P>0.05). Moreover, low-potency inhibitors of PARP-1 increased PDX-1 expression down-regulated by FFA-treatment.

Conclusions: These findings suggested that low-potency inhibitors of poly(ADP-ribose) polymerases could protect rat RINm5F cell line against free fatty acid-induced apoptosis, and it was through regulatory pathway of regulating PDX-1 expression.

Key words

type 2 diabetes - FFA - inhibitors of poly(ADP-ribose) polymerase - RINm5F cell line

References

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1 Joint first author.

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