Inhibition of TBK1/IKKε Promotes Regeneration of Pancreatic β-cells

• Main Authors: Jin Xu, Yun-Fang Jia, Subhasish Tapadar, Jessica D. Weaver, Idris O. Raji, Deeti J. Pithadia, Naureen Javeed, Andrés J. García, Doo-Sup Choi, Aleksey V. Matveyenko, Adegboyega K. Oyelere, Chong Hyun Shin
• Format: Article
• Language: English
• Published: Nature Publishing Group 2018-10-01
• Series: Scientific Reports
• Subjects: TANK-binding Kinase 1 (TBK1); Transgenic Zebrafish Model; Isoxazolyl; Supplemental Experimental Procedures; Amlexanox
• Online Access: https://doi.org/10.1038/s41598-018-33875-0

Abstract β-cell proliferation induction is a promising therapeutic strategy to restore β-cell mass. By screening small molecules in a transgenic zebrafish model of type 1 diabetes, we identified inhibitors of non-canonical IκB kinases (IKKs), TANK-binding kinase 1 (TBK1) and IκB kinase ε (IKKε), as enhancers of β-cell regeneration. The most potent β-cell regeneration enhancer was a cinnamic acid derivative (E)-3-(3-phenylbenzo[c]isoxazol-5-yl)acrylic acid (PIAA), which, acting through the cAMP-dependent protein kinase A (PKA), stimulated β-cell-specific proliferation by increasing cyclic AMP (cAMP) levels and mechanistic target of rapamycin (mTOR) activity. A combination of PIAA and cilostamide, an inhibitor of β-cell-enriched cAMP hydrolyzing enzyme phosphodiesterase (PDE) 3, enhanced β-cell proliferation, whereas overexpression of PDE3 blunted the mitogenic effect of PIAA in zebrafish. PIAA augmented proliferation of INS-1β-cells and β-cells in mammalian islets including human islets with elevation in cAMP levels and insulin secretion. PIAA improved glycemic control in streptozotocin (STZ)-induced diabetic mice with increases in β-cell proliferation, β-cell area, and insulin content in the pancreas. Collectively, these data reveal an evolutionarily conserved and critical role of TBK1/IKKε suppression in expanding functional β-cell mass.