We report the efficacy of a new peptide with agonism at the glucagon and GLP-1 receptors that has potent, sustained satiation-inducing and lipolytic effects. Selective chemical modification to glucagon resulted in a loss of specificity, with minimal change to inherent activity. The structural basis for the co-agonism appears to be a combination of local positional interactions and a change in secondary structure. Two co-agonist peptides differing from each other only in their level of glucagon receptor agonism were studied in rodent obesity models. Administration of PEGylated peptides once per week normalized adiposity and glucose tolerance in diet-induced obese mice. Reduction of body weight was achieved by a loss of body fat resulting from decreased food intake and increased energy expenditure. These preclinical studies indicate that when full GLP-1 agonism is augmented with an appropriate degree of glucagon receptor activation, body fat reduction can be substantially enhanced without any overt adverse effects.

Summary Autophagy promotes tumor growth by generating nutrients from the degradation of intracellular structures. Here we establish, using shRNAs, a dominant negative mutant, and a pharmacologic inhibitor, mefenamic acid (MFA), that the Transient Receptor Potential Melastatin 3 (TRPM3) channel promotes growth of clear cell renal cell carcinoma (ccRCC) and stimulates MAP1LC3A (LC3A) and MAP1LC3B (LC3B) autophagy. Increased expression of TRPM3 in RCC leads to Ca2+ influx, activation of CAMKK2, AMPK, and ULK1, and phagophore formation. In addition, TRPM3 Ca2+ and Zn2+ fluxes inhibit miR-214 which directly targets LC3A and LC3B. The von Hippel-Lindau tumor suppressor (VHL) represses TRPM3 through miR-204 directly and indirectly through another miR-204 target, Caveolin 1 (CAV1).

Insulin signaling can be modulated by several isoforms of PKC in peripheral tissues. Here, we assessed whether one specific isoform, PKC-θ, was expressed in critical CNS regions that regulate energy balance and whether it mediated the deleterious effects of diets high in fat, specifically palmitic acid, on hypothalamic insulin activity in rats and mice. Using a combination of in situ hybridization and immunohistochemistry, we found that PKC-θ was expressed in discrete neuronal populations of the arcuate nucleus, specifically the neuropeptide Y/agouti-related protein neurons and the dorsal medial nucleus in the hypothalamus. CNS exposure to palmitic acid via direct infusion or by oral gavage increased the localization of PKC-θ to cell membranes in the hypothalamus, which was associated with impaired hypothalamic insulin and leptin signaling. This finding was specific for palmitic acid, as the monounsaturated fatty acid, oleic acid, neither increased membrane localization of PKC-θ nor induced insulin resistance. Finally, arcuate-specific knockdown of PKC-θ attenuated diet-induced obesity and improved insulin signaling. These results suggest that many of the deleterious effects of high-fat diets, specifically those enriched with palmitic acid, are CNS mediated via PKC-θ activation, resulting in reduced insulin activity.

During the preparation of the manuscript, the number of samples used for the quantification of RT-PCR depicted in Figure 2E was stated incorrectly. The corrected legend appears below.(E) mRNA expression of TRPA1 and TRPM8 in the DRG after inflammation, as detected by RT-PCR. Quantification of RT-PCR data is shown at right. Data represent mean ± SD; n = 3 per group. *P < 0.05 compared with the naive control.The authors regret the error. During the preparation of the manuscript, the vehicle for ICV fatty acid infusion was incorrectly described. The incorrect description is on page 2586. The corrected paragraph appears below. Fatty acid infusion.Oleate (Oleic Acid-Cyclodextrin Complex; Sigma-Aldrich) was dissolved in PBS. Palmitate was first dissolved in absolute ethanol to make a 5 mM stock solution, which was then further dissolved in PBS. Rats were implanted with a cannula aimed into the third ventricle as described above. The cannula was connected via a polyethylene catheter to a subcutaneous osmotic minipump (Alza Corporation) filled with either palmitic or oleic acid (equimolar concentrations, 10 μmol/l) or vehicle (PBS) for continuous infusion over 3 days. The fatty acids were infused at a rate of 12 μl/d (or 8.3 nl/min); thus, we infused a total volume of 36 μl/3 d, which represents 1.8 nmol/3 d (i.e., 0.41 pmol/min).The authors regret the error.

The G protein-coupled receptor 83 (Gpr83) is widely expressed in brain regions regulating energy metabolism. Here we report that hypothalamic expression of Gpr83 is regulated in response to nutrient availability and is decreased in obese mice compared with lean mice. In the arcuate nucleus, Gpr83 colocalizes with the ghrelin receptor (Ghsr1a) and the agouti-related protein. In vitro analyses show heterodimerization of Gpr83 with Ghsr1a diminishes activation of Ghsr1a by acyl-ghrelin. The orexigenic and adipogenic effect of ghrelin is accordingly potentiated in Gpr83-deficient mice. Interestingly, Gpr83 knock-out mice have normal body weight and glucose tolerance when fed a regular chow diet, but are protected from obesity and glucose intolerance when challenged with a high-fat diet, despite hyperphagia and increased hypothalamic expression of agouti-related protein, Npy, Hcrt and Ghsr1a. Together, our data suggest that Gpr83 modulates ghrelin action but also indicate that Gpr83 regulates systemic metabolism through other ghrelin-independent pathways.