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Glucolipotoxicity (GLT), in which elevated levels of glucose and fatty acids have deleterious effects on b-cell biology, is thought to be one of the major contributors in progression of type 2 diabetes. In search of novel small molecules that protect b-cells against GLT, we previously discovered KD025, an inhibitor of Rho-associated coiled-coil-containing kinase isoform 2 (ROCK2), as a GLT-protective compound in INS-1E cells and dissociated human islets. To further understand the mechanism of action of KD025, we found that pharmacological and genetic inhibition of ROCK2 was not responsible for the protective effects of KD025 against GLT. Instead, kinase profiling revealed that KD025 potently inhibits catalytic subunits of casein kinase 2 (CK2), a constitutively active serine/threonine kinase. We experimentally verified that the inhibition of one of the catalytic subunits of casein kinase 2, CK2A1, but not CK2A2, improved cell viability when challenged with GLT. We conclude that KD025 inhibits CK2 to protect b-cells from GLT. [ABSTRACT FROM AUTHOR]

Pancreatic elastase (PE) is a serine protease produced by pancreatic acinar cells. PE is mainly secreted in the intestine during digestion, and is also detectable in stromal pancreatic tissue, including the ECM of islets. Recently, we identified serpinB1 (SB1), a protease inhibitor, as a promoter of human β-cell proliferation by inhibiting PE activity and demonstrated that the PE inhibitor, sivelestat, also induced β-cell regeneration. Here, we report the identification two novel PE inhibitors: telaprevir, an antiviral drug, and tebipenem, an antibiotic. We observed that telaprevir and tebipenem inhibited human PE (hPE) with greater or similar potency than sivelestat respectively (IC50: telaprevir 15.7nM, tebipenem 3.6µM, sivelestat 2.3 µM; n=3). We then tested the effects of the compounds in in vitro cultures of human islets. Telaprevir and tebipenem each increased proliferating human β-cells (∼4-fold and 1.5-fold increase respectively; n=6) compared to vehicle-treated islets. Furthermore, in an independent study, both compounds (at 10µM), stimulated β-cell regeneration in a zebrafish model resulting in ∼1.5-fold increase in insulin+ cells in treated versus non-treated groups. Finally, to identify pathways modulated by PE we treated human islets with the two compounds for 10 or 30 minutes and performed a phosphoprotein microarray assay (Kinexus, CA). We discovered that inhibition of hPE increased phosphorylation levels of PXN-PAK proteins belonging to the focal adhesion pathway. In addition, phosphorylation on the effectors of Protease-activated receptor 2 (PAR2) signaling (i.e., PKC, PYK2 and Src) were increased, resulting in the activation of ERK1/2 proteins and the mitogenic pathway in β-cells. These findings provide new insights regarding the molecular mechanisms underlying regulation of β-cell proliferation processes by PE, leading to identification of potential molecular targets that can be modulated in the long-term goal of treating diabetes. Disclosure: G. Basile: None. A. Vetere: None. K. Liu: None. J. Hu: None. O. Andersson: None. B. Wagner: None. R. Kulkarni: None. [ABSTRACT FROM AUTHOR]