Intraocular pressure-sensitive retinal ganglion cell degeneration is a hallmark of glaucoma, the leading cause of irreversible blindness. Here, we used RNA-sequencing and metabolomics to examine early glaucoma in DBA/2J mice. We demonstrate gene expression changes that significantly impact pathways mediating the metabolism and transport of glucose and pyruvate. Subsequent metabolic studies characterized an intraocular pressure (IOP)-dependent decline in retinal pyruvate levels coupled to dysregulated glucose metabolism prior to detectable optic nerve degeneration. Remarkably, retinal glucose levels were elevated 50-fold, consistent with decreased glycolysis but possibly including glycogen mobilization and other metabolic changes. Oral supplementation of the glycolytic product pyruvate strongly protected from neurodegeneration in both rat and mouse models of glaucoma. Investigating further, we detected mTOR activation at the mechanistic nexus of neurodegeneration and metabolism. Rapamycin-induced inhibition of mTOR robustly prevented glaucomatous neurodegeneration, supporting a damaging role for IOP-induced mTOR activation in perturbing metabolism and promoting glaucoma. Together, these findings support the use of treatments that limit metabolic disturbances and provide bioenergetic support. Such treatments provide a readily translatable strategy that warrants investigation in clinical trials.

Background: Fatty acid amide hydrolase (FAAH) belongs to the family of amidase signature proteins and is involved in N-acylethanolamine (NAE) metabolism. Results: New synthetic phenoxyacyl-ethanolamide compounds increased the amidohydrolase activity of FAAH. Conclusion: Phenoxyacyl-ethanolamide compounds increased the activity of the FAAH enzyme in plants and animals. Significance: New properties of FAAH proteins were revealed with these phenoxyacyl-ethanolamide compounds, and the potential for their applications in vivo was demonstrated.

HMG-CoA lyase (HMGCL 4 ; EC 4.1.3.4) catalyzes a cationdependent cleavage of substrate into acetyl-CoA and acetoacetate (Scheme 1) (1). This reaction is a key step in ketogenesis, the products of which support anaplerotic metabolism in bacteria (2) and energy production in nonhepatic animal tissues (3). Ketogenesis is particularly important to human metabolism during the prenatal period and during fasting or starvation. In accordance with these physiological roles, it is not surprising that gene knock-out in mice results in embryonic lethality (4). The physiological importance of the enzyme in humans is underscored by the observation that mutations that diminish HMGCL activity correlate with inherited metabolic disease that can be lethal if uncontrolled (5).A variety of human mutations, including many point mutations in protein-coding exons of the gene, have been documented (6). A computational modeling approach was used to explain the molecular basis for some mutations linked to inherited disease (7). This led to the prediction that HMGCL adopts a ␤/␣-barrel fold and a proposal that the acyl-S-pantetheine moiety of the bound substrate passes through the barrel lumen. Initial structural work on human HMGCL liganded to cation and hydroxyglutarate (8) demonstrated that the folding prediction was reasonable but that the substrate binding proposal was unlikely to be correct. The positions of bound cation and hydroxyglutarate (from hydrolyzed hydroxyglutaryl-CoA) indicated the catalytic site to be positioned at the C-terminal end of the barrel, but the absence of a full acyl-CoA molecule in the experimentally determined structure limited detailed insight into the substrate-binding site.To more fully address questions regarding the conformation of bound substrate, activator cation liganding, details concerning reaction chemistry and specificity, as well as the molecular basis for certain inherited HMGCL deficiencies, new structural information on enzyme bound to an intact acyl-CoA molecule is required. To remedy this need, complexes of the WT enzyme with the competitive inhibitor 3-hydroxyglutaryl-CoA and also of catalytically deficient R41M enzyme with the authentic substrate HMG-CoA have been supplemented with the activator cation Mg 2ϩ , and crystallization of the desired ternary complexes has been accomplished. Diffraction quality crystals have been produced, supporting three-dimensional structural determinations for ternary complexes of enzyme, cation, and either the acyl-CoA substrate or inhibitory analog. These findings are

Background: Ketone bodies have been implicated not only in energy metabolism, but also in lipogenesis. Results: Discovery and characterization of human extramitochondrial HMG-CoA lyase-like protein (HMGCLL1) has been accomplished. Conclusion: Catalytically active HMGCLL1 is myristoylated and vesicle associated. Significance: Extramitochondrial HMG-CoA lyase may be crucial to lipid biosynthesis or to energy metabolism in certain tissues and cancer cells.

Our data suggest that RGC function as well as interactions of RGCs with other retinal cell types is impaired during glaucoma. In addition, a later OP wavelet denoted as OP4 in this study was identified as a very reproducible indicator of loss of visual function in the glaucoma mouse model.