Inhibition of the MAP3 kinase Tpl2 protects rodent and human [beta]-cells from apoptosis and dysfunction induced by cytokines and enhances anti-inflammatory actions of exendin-4

• Published in: Cell death & disease 2016-01, Vol.7, p.e2065
• Main Authors: Varin, E M, Wojtusciszyn, A, Broca, C, Muller, D, Ravier, M A, Ceppo, F, Renard, E, Tanti, J-f, Dalle, S
• Format: Article
• Language: English
• Subjects: Apoptosis; Cytokines; Cytotoxicity; Diabetes; Pathogenesis; Protein expression
• ISSN: 2041-4889
• DOI: 10.1038/cddis.2015.399

Proinflammatory cytokines exert cytotoxic effects on -cells, and are involved in the pathogenesis of type I and type II diabetes and in the drastic loss of -cells following islet transplantation. Cytokines induce apoptosis and alter the function of differentiated -cells. Although the MAP3 kinase tumor progression locus 2 (Tpl2) is known to integrate signals from inflammatory stimuli in macrophages, fibroblasts and adipocytes, its role in -cells is unknown. We demonstrate that Tpl2 is expressed in INS-1E -cells, mouse and human islets, is activated and upregulated by cytokines and mediates ERK1/2, JNK and p38 activation. Tpl2 inhibition protects -cells, mouse and human islets from cytokine-induced apoptosis and preserves glucose-induced insulin secretion in mouse and human islets exposed to cytokines. Moreover, Tpl2 inhibition does not affect survival or positive effects of glucose (i.e., ERK1/2 phosphorylation and basal insulin secretion). The protection against cytokine-induced -cell apoptosis is strengthened when Tpl2 inhibition is combined with the glucagon-like peptide-1 (GLP-1) analog exendin-4 in INS-1E cells. Furthermore, when combined with exendin-4, Tpl2 inhibition prevents cytokine-induced death and dysfunction of human islets. This study proposes that Tpl2 inhibitors, used either alone or combined with a GLP-1 analog, represent potential novel and effective therapeutic strategies to protect diabetic -cells.