A small molecule inhibitor of Nicotinamide N-methyltransferase for the treatment of metabolic disorders

Abstract

Nicotinamide N-methyltransferase (NNMT) is a cytosolic enzyme that catalyzes the transfer of a methyl group from the co-factor S-adenosyl-L-methionine (SAM) onto the substrate, nicotinamide (NA) to form 1-methyl-nicotinamide (MNA). Higher NNMT expression and MNA concentrations have been associated with obesity and type-2 diabetes. Here we report a small molecule analog of NA, JBSNF-000088, that inhibits NNMT activity, reduces MNA levels and drives insulin sensitization, glucose modulation and body weight reduction in animal models of metabolic disease. In mice with high fat diet (HFD)-induced obesity, JBSNF-000088 treatment caused a reduction in body weight, improved insulin sensitivity and normalized glucose tolerance to the level of lean control mice. These effects were not seen in NNMT knockout mice on HFD, confirming specificity of JBSNF-000088. The compound also improved glucose handling in ob/ob and db/db mice albeit to a lesser extent and in the absence of weight loss. Co-crystal structure analysis revealed the presence of the N-methylated product of JBSNF-000088 bound to the NNMT protein. The N-methylated product was also detected in the plasma of mice treated with JBSNF-000088. Hence, JBSNF-000088 may act as a slow-turnover substrate analog, driving the observed metabolic benefits.

Genetic Nicotinamide N-Methyltransferase (Nnmt) Deficiency in Male Mice Improves Insulin Sensitivity in Diet-Induced Obesity but Does Not Affect Glucose Tolerance

“…Our investigations add further evidence that a reduction of NNMT inhibits weight gain and protects against associated negative metabolic effects in models of dietinduced obesity. This may represent a viable pharmacological target for future treatment of such conditions (16,28,29). Consistent effects of NNMT-specific ASOs, small-molecule inhibition (12,16,28,29), and the genetic model described here provide strong evidence for the specificity of NNMT modulation.…”

“…In studies with ASOs or inhibitor, adult mice are used and, as such, this developmental window of opportunity may be missed (30). Alternatively, residual NNMT activity (10-40%) (12,16) may impede compensatory mechanisms that mediate adaptation to a null situation. Furthermore, it is possible that NNMT concentration within a certain range (in adipose or other tissues) is required to mediate the observed positive effects, whereas complete deletion negates these.…”

“…NNMT 2/2 and WT females were fed a WD for 18 weeks. From week 13 to 18, animals were treated daily with a vehicle (30% PEG200) by oral gavage to simulate pharmacological intervention with a test compound, analogous to another set of experiments (16), but not in weeks 1-12 of the WD, in which we assessed body composition, body weight (BW) gain, and food intake. In week 18, an oral glucose tolerance test (oGTT) was performed in PEG200treated mice.…”

High-Affinity Alkynyl Bisubstrate Inhibitors of Nicotinamide N-Methyltransferase (NNMT)

“…25 Importantly, if two weak inhibitors that bind a protein at distinct sites are linked in an optimal manner, the resulting bisubstrate inhibitors can obtain several orders of magnitude increase in binding affinity. 26,27 . As a result, linker identity is crucial to properly position the key interacting groups of the two component molecules and minimize unfavorable interactions between the linker and the protein.…”

Development of fluorescence polarization-based competition assay for nicotinamideN-methyltransferase

“…Despite recent progresses in the development of NNMT bisubstrate inhibitors achieving inhibitory activity at nM levels, limited cell permeability restrains their applications in cellular studies [12][13][14]. Meanwhile, available small molecule inhibitors mainly only bear moderate activity at µM levels [15,16]. Hence, there remains an urgent need for new cell-potent inhibitors to delineate the physiological and pathological functions of NNMT.…”