Diabetes reversal by inhibition of the low-molecular-weight tyrosine phosphatase.

Obesity-associated insulin resistance plays a central role in type 2 diabetes. As such, tyrosine phosphatases that dephosphorylate the insulin receptor (IR) are potential therapeutic targets. The low-molecular-weight protein tyrosine phosphatase (LMPTP) is a proposed IR phosphatase, yet its role in insulin signaling in vivo has not been defined. Here we show that global and liver-specific LMPTP deletion protects mice from high-fat diet-induced diabetes without affecting body weight. To examine the role of the catalytic activity of LMPTP, we developed a small-molecule inhibitor with a novel uncompetitive mechanism, a unique binding site at the opening of the catalytic pocket, and an exquisite selectivity over other phosphatases. This inhibitor is orally bioavailable, and it increases liver IR phosphorylation in vivo and reverses high-fat diet-induced diabetes. Our findings suggest that LMPTP is a key promoter of insulin resistance and that LMPTP inhibitors would be beneficial for treating type 2 diabetes

Development of a Testing Funnel for Identification of Small-Molecule Modulators Targeting Secretin Receptors

The secretin receptor (SCTR), a prototypical class B G protein-coupled receptor (GPCR), exerts its effects mainly by activating Gαs proteins upon binding of its endogenous peptide ligand secretin. SCTRs can be found in a variety of tissues and organs across species, including the pancreas, stomach, liver, heart, lung, colon, kidney, and brain. Beyond that, modulation of SCTR-mediated signaling has therapeutic potential for the treatment of multiple diseases, such as heart failure, obesity, and diabetes. However, no ligands other than secretin and its peptide analogs have been described to regulate SCTRs, probably due to inherent challenges in family B GPCR drug discovery. Here we report creation of a testing funnel that allowed targeted detection of SCTR small-molecule activators. Pursuing the strategy to identify positive allosteric modulators (PAMs), we established a unique primary screening assay employing a mixture of three orthosteric stimulators that was compared in a screening campaign testing 12,000 small-molecule compounds. Beyond that, we developed a comprehensive set of secondary assays, such as a radiolabel-free target engagement assay and a NanoBiT (NanoLuc Binary Technology)-based approach to detect β-arrestin-2 recruitment, all feasible in a high-throughput environment as well as capable of profiling ligands and hits regarding their effect on binding and receptor function. This combination of methods enabled the discovery of five promising scaffolds, four of which have been validated and further characterized with respect to their allosteric activities. We propose that our results may serve as starting points for developing the first in vivo active small molecules targeting SCTRs

1742-P: Targeting the Low Molecular Weight Protein Tyrosine Phosphatase for Obesity-Associated Diabetes Therapy

Obesity-associated insulin resistance plays a central role in the pathogenesis of type 2 diabetes. A promising approach to decrease insulin resistance in obesity is to inhibit the protein tyrosine phosphatases that negatively regulate insulin receptor signaling. The low molecular weight protein tyrosine phosphatase (LMPTP), encoded by the ACP1 gene, acts as a critical regulator of insulin signaling by dephosphorylating the activation motif of the insulin receptor. Human genetics studies suggest that high LMPTP catalytic activity promotes diabetes and insulin resistance in obesity. We recently discovered that LMPTP is a critical promoter of insulin resistance in obesity through an action on the liver and that pharmacological inhibition of LMPTP reverses obesity-induced diabetes in mice. Here we report our progress in the development of a new chemical series of LMPTP inhibitors that is orally bioavailable and effective at treating disease in obese diabetic mice. Disclosure S.M. Stanford: None. M.A. Diaz: None. J.J. Zou: None. R.J. Ardecky: None. A. Pinkerton: None. N. Bottini: Research Support; Self; Eli Lilly and Company, Gilead Sciences, Inc., Kyowa Hakko Kirin Co., Ltd., Roche Pharma. Funding American Diabetes Association/Pathway to Stop Diabetes (1-15-INI-13 to S.M.S.); National Institutes of Health (R01DK106233) </jats:sec

Design and synthesis of pyrazole derivatives as potent and selective inhibitors of tissue-nonspecific alkaline phosphatase (TNAP)

Tissue-nonspecific alkaline phosphatase (TNAP) plays a central role in regulating extracellular matrix calcification during bone formation and growth. High throughput screening (HTS) for small molecule TNAP inhibitors led to the identification of hits in the sub-micromolar potency range. We report the design, synthesis and in vitro evaluation of a series of pyrazole derivatives of a screening hit which are potent TNAP inhibitors exhibiting IC(50) values as low as 5 nM. A representative of the series was characterized in kinetic studies and determined to have a mode of inhibition not previously observed for TNAP inhibitors