CymaBay Therapeutics.

MyristoylCoA:protein N-myristoyltransferase (Nmt) catalyses the co-translational, covalent attachment of myristate (C14:0) to the amino-terminal glycine residue of a number of eukaryotic proteins involved in cellular growth and signal transduction. The NMT1 gene is essential for vegetative growth of Saccharomyces cerevisiae. Studies were carried out to determine if Nmt is also essential for vegetative growth of the pathogenic fungus Candida albicans. A strain of C. albicans was constructed in which one copy of NMT was partially deleted and disrupted. A Gly-447-->Asp mutation was introduced into the second NMT allele. This mutation produced marked reductions in catalytic efficiency at 24 and 37 degrees C, as judged by in vitro kinetic studies of the wild-type and mutant enzymes which had been expressed in, and purified from, Escherichia coli. The growth characteristics of isogenic NMT/NMT, NMT/delta nmt, and nmt delta/nmtG447D C. albicans strains were assessed under a variety of conditions. Only the nmt delta/nmtG447D strain required myristate for growth. This was true at both 24 and 37 degrees C. Palmitate could not substitute for myristate. Incubation of nmt delta/nmtG447D cells at 37 degrees C in the absence of myristate resulted in cell death as observed by the inability to form colonies on media supplemented with 500 microM myristate. Studies in an immunosuppressed-mouse model of C. albicans infection revealed that the NMT/delta nmt strain produced 100% lethality within 7 d after intravenous administration while the isogenic nmt delta/nmtG447G strain produced no deaths even after 21 d. These observations establish that Nmt is essential for vegetative growth of C. albicans and suggest that inhibitors of this acyltransferase may be therapeutically useful fungicidal agents.

No abstract

. 11-Aminoundecanoyl-SK-NH 2 and 11-aminoundecanoyl-SH-NH 2 establish that a simple alkyl backbone can maintain an appropriate distance between three elements critical for recognition by the fungal enzyme's peptide-binding site: a simple -terminal amino group, a ␤-hydroxyl, and an ⑀-amino group or an imidazole. These compounds contain one peptide bond and two chiral centers, suggesting that it may be feasible to incorporate these elements of recognition, or functionally equivalent mimics, into a fully de-peptidized Nmt inhibitor.

Lipotoxicity associated with insulin resistance is central to nonalcoholic steatohepatitis (NASH) pathogenesis. To date, only weight loss fully reverses NASH pathology, but mixed peroxisome proliferator–activated receptor‐alpha/delta (PPAR‐α/δ) agonists show some efficacy. Seladelpar (MBX‐8025), a selective PPAR‐δ agonist, improves atherogenic dyslipidemia. We therefore used this agent to test whether selective PPAR‐δ activation can reverse hepatic lipotoxicity and NASH in an obese, dyslipidemic, and diabetic mouse model. From weaning, female Alms1 mutant (foz/foz) mice and wild‐type littermates were fed an atherogenic diet for 16 weeks; groups (n = 8‐12) were then randomized to receive MBX‐8025 (10 mg/kg) or vehicle (1% methylcellulose) by gavage for 8 weeks. Despite minimally altering body weight, MBX‐8025 normalized hyperglycemia, hyperinsulinemia, and glucose disposal in foz/foz mice. Serum alanine aminotransferase ranged 300‐600 U/L in vehicle‐treated foz/foz mice; MBX‐8025 reduced alanine aminotransferase by 50%. In addition, MBX‐8025 normalized serum lipids and hepatic levels of free cholesterol and other lipotoxic lipids that were increased in vehicle‐treated foz/foz versus wild‐type mice. This abolished hepatocyte ballooning and apoptosis, substantially reduced steatosis and liver inflammation, and improved liver fibrosis. In vehicle‐treated foz/foz mice, the mean nonalcoholic fatty liver disease activity score was 6.9, indicating NASH; MBX‐8025 reversed NASH in all foz/foz mice (nonalcoholic fatty liver disease activity score 3.13). Conclusion: Seladelpar improves insulin sensitivity and reverses dyslipidemia and hepatic storage of lipotoxic lipids to improve NASH pathology in atherogenic diet–fed obese diabetic mice. Selective PPAR‐δ agonists act independently of weight reduction, but counter lipotoxicity related to insulin resistance, thereby providing a novel therapy for NASH. (Hepatology Communications 2017;1:663–674)