Zonation was similarly observed for the mitochondrial fatty acid oxidation enzymes, acyl-CoA dehydrogenase and very long chain (ACADVL; S3D) and 2,4-dienoyl CoA reductase 1 (DECR1; S3E), the http://www.selleckchem.com/products/kpt-330.html cytoplasmic enzymes acetyl-CoA carboxylase (ACACB; Figure S3F) and diacylglycerol O-acyltransferase 2 (DGAT2; Figure S3G) as well as the lipid droplet associated protein perilipin 1(PLIN1; Figure S3H). In particular, several proteins facilitating phospholipid metabolism also displayed zonal expression. Preferential perivenular (zone 3) zonation was clearly evident for choline kinase �� (CHKA; Figure S3I), phosphocholine cytidylyltransferase 1 (PYCT1A; Figure S3J), phosphatidylethanolamine N-methyltransferase (PEMT; Figure S3K), glycerol-3-phosphate acyltransferase 2 (GPAT2; S3M) as well as the phospholipases A2 G15, A2 G4F and B1(PLA2G15, PLA2G4F and PLA2B1 Figure S3N-S3P, respectively).

Only phosphocholine cytidylyltransferase 2 (PCYT2; Figure S3L) displayed a perivenular dominant (zone 1 to zone 3) expression pattern. To gain insight into what, if any, changes may exist with regard to PC biosynthetic enzymes commensurate with NAFLD progression, we examined in situ the localization of PEMT, a primary PC biosynthetic enzyme. Figure 5A illustrates the strong perivenular localization of this enzyme in a histologically normal obese liver. This contrasts with panlobular distribution of the enzyme in SS (Figure 5B) and NASH, and with notable localization in necroinflammatory sites in NASH specimens (Figure 5C). Figure 5 Phosphatidylethanolamine methyltransferase (PEMT) localization differs with progression of NAFLD.

Discussion Aberrant hepatic lipid metabolism has long been proposed to be central in the pathogenesis of NASH, but the exact mechanism(s) underlying necroinflammatory changes on background steatosis remain to be fully understood. The differential abundance of phospholipids, particularly PCs and PEs, has been studied quantitatively but these studies have largely been either in mice [34], [35], [36], [37], in anthropomorphically-diverse cohorts [30], or with destructive analytical methods such as methylation or acid/alkaline digestion that provide information on fatty acid composition within a lipid class but do not identify a specific PC [31], [38], [39]. The current study identifies, quantifies and localizes specific choline-containing lipids in human liver and reveals a previously unappreciated zonation of specific molecular PCs that are either lost or preserved in association with NAFLD severity. Given these ostensibly protein-mediated changes, we further demonstrated the zonation pattern of one hallmark PC metabolic enzyme, AV-951 PEMT.