Short-chain fatty acids (SCFAs), primarily acetate, propionate, and butyrate, are metabolites formed by gut microbiota from complex dietary carbohydrates. Butyrate and acetate were reported to protect against diet-induced obesity without causing hypophagia, while propionate was shown to reduce food intake. However, the underlying mechanisms for these effects are unclear. It was suggested that SCFAs may regulate gut hormones via their endogenous receptors Free fatty acid receptors 2 (FFAR2) and 3 (FFAR3), but direct evidence is lacking. We examined the effects of SCFA administration in mice, and show that butyrate, propionate, and acetate all protected against diet-induced obesity and insulin resistance. Butyrate and propionate, but not acetate, induce gut hormones and reduce food intake. As FFAR3 is the common receptor activated by butyrate and propionate, we examined these effects in FFAR3-deficient mice. The effects of butyrate and propionate on body weight and food intake are independent of FFAR3. In addition, FFAR3 plays a minor role in butyrate stimulation of Glucagon-like peptide-1, and is not required for butyrate- and propionate-dependent induction of Glucose-dependent insulinotropic peptide. Finally, FFAR3-deficient mice show normal body weight and glucose homeostasis. Stimulation of gut hormones and food intake inhibition by butyrate and propionate may represent a novel mechanism by which gut microbiota regulates host metabolism. These effects are largely intact in FFAR3-deficient mice, indicating additional mediators are required for these beneficial effects.

Isolated methylmalonic acidemia/aciduria (MMA) is a devastating metabolic disorder with poor outcomes despite current medical treatments. Like other mitochondrial enzymopathies, enzyme replacement therapy (ERT) is not available, and although promising, AAV gene therapy can be limited by pre-existing immunity and has been associated with genotoxicity in mice. To develop a new class of therapy for MMA, we generated a pseudoU-modified codon-optimized mRNA encoding human methylmalonyl-CoA mutase (hMUT), the enzyme most frequently mutated in MMA, and encapsulated it into biodegradable lipid nanoparticles (LNPs). Intravenous (i.v.) administration of hMUT mRNA in two different mouse models of MMA resulted in a 75%-85% reduction in plasma methylmalonic acid and was associated with increased hMUT protein expression and activity in liver. Repeat dosing of hMUT mRNA reduced circulating metabolites and dramatically improved survival and weight gain. Additionally, repeat i.v. dosing did not increase markers of liver toxicity or inflammation in heterozygote MMA mice.

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Sox3 is expressed in developing gonads and in the brain. Evolutionary evidence suggests that the X-chromosomal Sox3 gene may be the ancestral precursor of Sry, a sex-determining gene, and Sox3 has been proposed to play a role in sex determination. However, patients with mutations in SOX3 exhibit normal gonadal determination but are mentally retarded and have short stature secondary to growth hormone (GH) deficiency. We used Cre-LoxP targeted mutagenesis to delete Sox3 from mice. Null mice of both sexes had no overt behavioral deficits and exhibited normal GH gene expression. Low body weight was observed for some mice; overgrowth and misalignment of the front teeth was observed consistently. Female Sox3 null mice (؊/؊) developed ovaries but had excess follicular atresia, ovulation of defective oocytes, and severely reduced fertility. Pituitary (luteinizing hormone and follicle-stimulating hormone) and uterine functions were normal in females. Hemizygous male null mice (؊/Y) developed testes but were hypogonadal. Testis weight was reduced by 42%, and there was extensive Sertoli cell vacuolization, loss of germ cells, reduced sperm counts, and disruption of the seminiferous tubules. We conclude that Sox3 is not required for gonadal determination but is important for normal oocyte development and male testis differentiation and gametogenesis.Sox3 is a single-exon gene located on the X chromosome (38) and expressed in the brain and gonads. It is a member of the high-mobility-group (HMG) family of transcription factors and was cloned based on HMG-box homology to Sry (10). Sry was identified as the male-determining gene over 10 years ago (37), and there has been great interest in the subsequent genetic cascade that directs gonadal determination and development. Evolutionary evidence suggests that Sox3 may be an ancestral precursor of Sry (14), and it has been proposed that Sox3 might antagonize Sry action to influence sex determination (15). Sox3 is also expressed in the brain from the earliest stages of development (46), preceding gonadal expression, suggesting a role for Sox3 in brain formation and cognitive function.Some of the genes implicated in the formation of the indeterminate gonad (not committed to the male or female pathway) from the urogenital ridge have been identified (e.g., Lhx9, Ftzf1/Sf-1, and Wt-1) (7,22,29). Several other genes have been found to play a role in testis determination and differentiation, largely based on naturally occurring mutations in humans or targeted mutagenesis of candidate genes in mice. Human heterozygous mutations in SOX9, for example, cause campomelic dysplasia (44), a skeletal abnormality that is frequently associated with ambiguous genitalia (12). Dhh is required for the normal development and function of the peritubular myoid and Leydig cells (9), and its absence creates a disorganized testis with impaired spermatogenesis. Fgf9 null mice exhibit a spectrum of testicular defects, ranging from hypoplasia to XY sex reversal (11), and the absence of Wnt4 causes abnormal vascul...

Fabry disease is an X-linked lysosomal storage disease caused by loss of alpha galactosidase A (a-Gal A) activity and is characterized by progressive accumulation of globotriaosylceramide and its analogs in all cells and tissues. Although enzyme replacement therapy (ERT) is considered standard of care, the long-term effects of ERT on renal and cardiac manifestations remain uncertain and thus novel therapies are desirable. We herein report preclinical studies evaluating systemic messenger RNA (mRNA) encoding human a-Gal A in wild-type (WT) mice, a-Gal A-deficient mice, and WT non-human primates (NHPs). The pharmacokinetics and distribution of h-a-Gal A mRNA encoded protein in WT mice demonstrated prolonged half-lives of a-Gal A in tissues and plasma. Single intravenous administration of h-a-Gal A mRNA to Gla-deficient mice showed dose-dependent protein activity and substrate reduction. Moreover, long duration (up to 6 weeks) of substrate reductions in tissues and plasma were observed after a single injection. Furthermore, repeat i.v. administration of h-a-Gal A mRNA showed a sustained pharmacodynamic response and efficacy in Fabry mice model. Lastly, multiple administrations to non-human primates confirmed safety and translatability. Taken together, these studies across species demonstrate preclinical proof-of-concept of systemic mRNA therapy for the treatment of Fabry disease and this approach may be useful for other lysosomal storage disorders.