Free fatty acid receptor 1 agonist, MR1704, lowers blood glucose levels in rats unresponsive to the sulfonylurea, glibenclamide.

Preclinical Research & Development MR1704 is a selective G protein-coupled receptor 40/free fatty acid receptor 1 agonist, which exhibited favorable pharmacokinetic profiles and glucose-lowering effects in animal models. We studied the effects of MR1704 in a sulfonylurea-desensitized Sprague-Dawley rat model and evaluated the risk of pancreatic ß-cell exhaustion compared to that of glibenclamide in Zucker fatty rats. Rats fed ad libitum a diet containing 0.03% glibenclamide exhibited lower non-fasting blood glucose levels compared to those in rats fed a control diet during the first 6 days. However, the response to glibenclamide disappeared on day 9. In a rat oral glucose tolerance test (OGTT), MR1704 reduced the plasma glucose excursion, whereas glibenclamide did not show this effect. In Zucker fatty rats, oral administration of MR1704 reduced glucose excursion during the OGTT, and the effects of MR1704 were maintained after 2-week treatment. In contrast, the glucose-lowering effects of glibenclamide were diminished, and glucose tolerance was aggravated after 2-week treatment. These results indicated that MR1704 provided more sustainable effects compared to those of the sulfonylurea, glibenclamide suggesting that MR1704 may be an attractive therapeutic option for diabetic patients who are unresponsive to sulfonylurea treatment.

A novel free fatty acid receptor 1 (GPR40/FFAR1) agonist, MR1704, enhances glucose-dependent insulin secretion and improves glucose homeostasis in rats.

Activation of G protein-coupled receptor 40/Free fatty acid receptor 1 (GPR40/FFAR1), which is highly expressed in pancreatic ß cells, is considered an important pharmacologic target for the treatment of type 2 diabetes mellitus. The aim of this study was to determine the effect of MR1704, a novel GPR40/FFAR1 agonist, on glucose homeostasis in rats. MR1704 is a highly potent and selective, orally bioavailable agonist with similar in vitro potencies among humans, mice, and rats. Treatment of rat islets with MR1704 increased glucose-dependent insulin secretion. Augmentation of glucose-dependent insulin secretion was abolished by adding a GPR40/FFAR1 antagonist. In mouse, insulinoma MIN6 cells, palmitic acid induced the activity of caspase 3/7 after a 72-h exposure, while pharmacologically active concentrations of MR1704 did not. In an oral glucose tolerance test in normal Sprague-Dawley rats, orally administered MR1704 (1-10 mg·kg-1 ) reduced plasma glucose excursion and enhanced insulin secretion, but MR1704 did not induce hypoglycemia, even at 300 mg·kg-1 , in fasted Sprague-Dawley rats. In addition, orally administered MR1704 reduced plasma glucose excursion and enhanced insulin secretion in diabetic Goto-Kakizaki rats. Oral administration of MR1704 once daily to Goto-Kakizaki rats reduced their blood glucose levels during a 5-week treatment period without reducing pancreatic insulin content; as a result, hemoglobin A1C levels significantly decreased. These results suggest that MR1704 improves glucose homeostasis through glucose-dependent insulin secretion with a low risk of hypoglycemia and pancreatic toxicity. MR1704 shows promise as a new, glucose-lowering drug to treat type 2 diabetes mellitus.

The novel Nrf2 inducer TFM-735 ameliorates experimental autoimmune encephalomyelitis in mice.

The transcription factor NF-E2-related factor 2 (Nrf2) is a key regulator of cellular defense mechanisms against oxidative stress. Multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system, is characterized by progressive demyelination and neurodegeneration induced by inflammation and oxidative stress. The induction of Nrf2 signaling has been shown to inhibit disease development and progression in the experimental autoimmune encephalomyelitis (EAE) model of MS in mice. In the present study, we performed a high-throughput screening assay using a chimeric construct of the N-terminal portion of Nrf2 fused to LacZ. Using this approach, we identified the novel Nrf2 inducer TFM-735. Using human primary cell profiling systems, we found that TFM-735 inhibited T cell proliferation and exerted immuno-modulatory effects by inhibiting the production of IL-6 and IL-17. TFM-735 also inhibited IL-17 secretion from human peripheral blood mononuclear cells stimulated with anti-CD3 and anti-CD28. In EAE mice treated with TFM-735, the expression of the Nrf2 target gene Nqo1 increased in the brain and spleen, disease severity was ameliorated, and plasma IL-17 levels decreased. Furthermore, TFM-735 inhibited luciferase activity in Wim-6 transgenic EAE mice expressing the human interleukin 6-luciferase (hIL6-BAC-Luc) reporter. Therefore, these findings indicate that TFM-735 is a potent Nrf2 inducer that inhibits inflammatory cytokine production and disease progression in mice with EAE and that TFM-735 is a promising therapeutic agent for MS.

Gelsolin, an actin regulatory protein, is required for differentiation of mouse 3T3-L1 cells into adipocytes.

To elucidate molecular mechanisms of adipocyte differentiation, we previously isolated TC10-like/ TC10betaLong (TCL/TC10betaL), which was transiently expressed in the early phase of adipogenesis of 3T3-L1 cells and seemed to be a positive regulator of adipogenesis. By using TCL/TC10betaL-overexpressing NIH-3T3 cells, we also isolated gelsolin as a gene whose expression was up-regulated by TCL/TC10betaL. However, the roles of gelsolin in adipocyte differentiation are unclear. In this paper we characterized the function of gelsolin in adipogenesis in 3T3-L1 cells. The level of gelsolin changed during adipocyte differentiation. Knockdown of the expression of gelsolin using RNAi inhibited adipocyte differentiation, and impaired the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) and CCAAT/enhancer-binding protein (C/EBP) alpha. Interestingly, the knockdown also impaired mitotic clonal expansion (MCE), and increased cell size, though it reduced levels of C/EBPbeta and C/EBPdelta, markers for the early stage of adipogenesis, only slightly. Gelsolin plays a crucial role in the differentiation of 3T3-L1 cells into adipocytes.

TC10-like/TC10betaLong regulates adipogenesis by controlling mitotic clonal expansion.

To elucidate molecular mechanisms of adipocyte differentiation, we previously isolated TC10-like/TC10betaLong (TCL/TC10betaL), regulators of G protein signaling 2 (RGS2), factor for adipocyte differentiation (fad) 104 and fad158, which were transiently expressed in the early phase of adipogenesis. These four genes seem to be positive regulators of adipogenesis, since their knockdown resulted in the inhibition of adipocyte differentiation. When growth-arrested 3T3-L1 cells were induced to differentiate, they first reentered the cell cycle and underwent several rounds of cell division, a process known as mitotic clonal expansion (MCE). Although MCE is required for completion of the differentiation program, its molecular mechanisms are not fully understood. We examined the roles of these four genes during MCE. Knockdown of the expression of TCL/TC10betaL impaired MCE, while that of RGS2 or fad104 had a rather weak effect and that of fad158 had no effect. The suppression of TCL/TC10betaL inhibited the incorporation of bromodeoxyuridine (BrdU), indicating that DNA synthesis was prevented by the knockdown. Interestingly, the knockdown of TCL/TC10betaL inhibited the expression of the CCAAT/enhancer-binding protein (C/EBP) family, C/EBPbeta and C/EBPdelta, during MCE. The results strongly suggest that TCL/TC10betaL regulates adipocyte differentiation by controlling MCE and this regulatory effect is closely linked to C/EBPbeta and C/EBPdelta expression.