Key pointsr We recently found that feeding healthy mice a diet with reduced levels of branched-chain amino acids (BCAAs), which are associated with insulin resistance in both humans and rodents, modestly improves glucose tolerance and slows fat mass gain.r In the present study, we show that a reduced BCAA diet promotes rapid fat mass loss without calorie restriction in obese mice.r Selective reduction of dietary BCAAs also restores glucose tolerance and insulin sensitivity to obese mice, even as they continue to consume a high-fat, high-sugar diet.r A low BCAA diet transiently induces FGF21 (fibroblast growth factor 21) and increases energy expenditure.r We suggest that dietary protein quality (i.e. the precise macronutrient composition of dietary protein) may impact the effectiveness of weight loss diets.Abstract Obesity and diabetes are increasing problems around the world, and although even moderate weight loss can improve metabolic health, reduced calorie diets are notoriously difficult to sustain. Branched-chain amino acids (BCAAs; leucine, isoleucine and valine) are elevated in the blood of obese, insulin-resistant humans and rodents. We recently demonstrated that specifically reducing dietary levels of BCAAs has beneficial effects on the metabolic health of young, growing mice, improving glucose tolerance and modestly slowing fat mass gain. In the present study, we examine the hypothesis that reducing dietary BCAAs will promote weight loss, reduce adiposity, and improve blood glucose control in diet-induced obese mice with pre-existing metabolic syndrome. We find that specifically reducing dietary BCAAs rapidly reverses diet-induced obesity and improves glucoregulatory control in diet-induced obese mice. Most dramatically, mice eating an otherwise unhealthy high-calorie, high-sugar Western diet with reduced levels of BCAAs lost weight and fat mass rapidly until regaining a normal weight. Importantly, this normalization of weight was mediated not by caloric restriction or increased activity, but by increased energy expenditure, and was accompanied by a transient induction of the energy balance regulating hormone FGF21 (fibroblast growth factor 21). Consumption of a Western diet reduced in BCAAs was also accompanied by a dramatic improvement in glucose tolerance and insulin resistance. Our results link dietary BCAAs with the regulation of metabolic health and energy balance in obese animals, and suggest that specifically reducing dietary BCAAs may represent a highly translatable option for the treatment of obesity and insulin resistance.

Objective. To identify and characterize a fully human antibody directed against B lymphocyte stimulator (BLyS), a tumor necrosis factor-related cytokine that plays a critical role in the regulation of B cell maturation and development. Elevated levels of BLyS have been implicated in the pathogenesis of autoimmune diseases.Methods. A human phage display library was screened for antibodies against human BLyS. A human monoclonal antibody, LymphoStat-B, specific for human BLyS was obtained from the library screening and subsequent affinity optimization mutagenesis. The antibody was tested for inhibition of human BLyS in vitro and in an in vivo murine model. Additionally, the consequences of BLyS inhibition were tested in vivo by administration of LymphoStat-B to cynomolgus monkeys.Results. LymphoStat-B bound with high affinity to human BLyS and inhibited the binding of BLyS to its

Previous studies of the interactions of NO with human hemoglobin have implied the predominance of reaction channels that alternatively eliminate NO by converting it to nitrate, or tightly complex it on the ␣ subunit ferrous hemes. Both channels could effectively quench NO bioactivity. More recent work has raised the idea that NO groups can efficiently transfer from the hemes to cysteine thiols within the ␤ subunit (cys␤-93) to form bioactive nitrosothiols. The regulation of NO function, through its chemical position in the hemoglobin, is supported by response to oxygen and to redox agents that modulate the molecular and electronic structure of the protein. In this article, we focus on reactions in which Fe(III) hemes could provide the oxidative requirements of this NO-group transfer chemistry. We report a detailed investigation of the reductive nitrosylation of human met-Hb, in which we demonstrate the production of S-nitroso (SNO)-Hb through a heme-Fe(III)NO intermediate. The production of SNO-Hb is strongly favored (over nitrite) when NO is gradually introduced in limited total quantities; in this situation, moreover, heme nitrosylation occurs primarily within the ␤ subunits of the hemoglobin tetramer. SNO-Hb can similarly be produced when Fe(II)NO hemes are subjected to mild oxidation. The reaction of deoxygenated hemoglobin with limited quantities of nitrite leads to the production of ␤ subunit Fe(II)NO hemes, with SNO-Hb produced on subsequent oxygenation. The common theme of these reactions is the effective coupling of heme-iron and NO redox chemistries. Collectively, they establish a connectivity between hemes and thiols in Hb, through which NO is readily dislodged from storage on the heme to form bioactive SNO-Hb.T he transfer of NO groups within human hemoglobin from hemes to cys(␤-93) thiols to form a bioactive nitrosothiol represents a novel intramolecular biochemistry that is both of fundamental interest and has considerable implications for understanding the physiological effects of NO in the regulation of vascular tension and blood f low. A requirement of this transfer, common to biological S-nitrosylation (1), is the redox activation of the NO group (2). In this article, we report the results of experiments that probe the idea that heme-iron valence change can support the oxidative requirements of NO-group transfer and thus efficiently lead to the production of S-nitroso (SNO)-Hb. As a model of the reaction between ferric hemes and NO, the reductive nitrosylation of human methemoglobin is examined in detail. Product distribution assays reveal that SNO-Hb is formed as a nitrosation product, which, moreover, is substantially favored over NO 2 Ϫ when NO is gradually introduced as a limiting reagent; furthermore, in this situation, heme nitrosylation occurs primarily within the ␤ subunits of the Hb tetramer. A kinetic analysis unambiguously reveals the intermediacy of heme-Fe(III)NO in this reaction. To extend our observations to reactions that could mimic this chemistry but do not require an accumula...