Figure 4. Pretreatment of β-cells with recombinant CXCL12 improves viability and induces a decrease in PARP-1 activity.

(A) Poly(ADP-ribosyl)ation level of wt cells and wt cells pretreated either with recombinant CXCL12 (80 ng/ml) or with 3AB (0.5 mM) before exposure to hydrogen peroxide, determined by immunoblot analysis with anti-PAR antibody. Poly(ADP-ribosyl)ation level of islet cells before and after treatment with hydrogen peroxide and islet cells pretreated with recombinant CXCL12 (80 ng/ml) (A, top panel). The PARP-1 protein level in these samples was determined by immunoblot analysis with anti-PARP-1 antibody (A, lower panel). (B) Viability assay of control and wt cells treated with IC₅₀ hydrogen peroxide and wt cells pretreated with recombinant CXCL12 or 3AB before treatment with hydrogen peroxide. Viability assay of islet cells before and after treatment with hydrogen peroxide and islet cells pretreated with recombinant CXCL12 (80 ng/ml). (C) mRNA levels of insulin wt Rin-5F and islet cells with or without pretreatment with recombinant CXCL12 before hydrogen peroxide treatment. The cells were exposed to hydrogen peroxide for 1 h, followed by 5 h of recovery in the cell culture media. The mRNA levels were determined by RT-qPCR and presented in the graphs depicting the changes in mRNA levels relative to β-actin. The results are expressed as means ± S.E.M. Means not sharing a common letter are significantly different between groups (p<0.05).