Recent studies have identified a genetic variant rs641738 near two genes encoding membrane bound O-acyltransferase domain-containing 7 (MBOAT7) and transmembrane channel-like 4 (TMC4) that associate with increased risk of non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), alcohol-related cirrhosis, and liver fibrosis in those infected with viral hepatitis (Buch et al., 2015; Mancina et al., 2016; Luukkonen et al., 2016; Thabet et al., 2016; Viitasalo et al., 2016; Krawczyk et al., 2017; Thabet et al., 2017). Based on hepatic expression quantitative trait loci analysis, it has been suggested that MBOAT7 loss of function promotes liver disease progression (Buch et al., 2015; Mancina et al., 2016; Luukkonen et al., 2016; Thabet et al., 2016; Viitasalo et al., 2016; Krawczyk et al., 2017; Thabet et al., 2017), but this has never been formally tested. Here we show that Mboat7 loss, but not Tmc4, in mice is sufficient to promote the progression of NAFLD in the setting of high fat diet. Mboat7 loss of function is associated with accumulation of its substrate lysophosphatidylinositol (LPI) lipids, and direct administration of LPI promotes hepatic inflammatory and fibrotic transcriptional changes in an Mboat7-dependent manner. These studies reveal a novel role for MBOAT7-driven acylation of LPI lipids in suppressing the progression of NAFLD.

SUMMARY Emerging evidence suggests that microbes resident in the human intestine represent a key environmental factor contributing to obesity-associated disorders. Here we demonstrate that the gut microbiota-initiated trimethylamine-N-oxide (TMAO)-generating pathway is linked to obesity and energy metabolism. In multiple clinical cohorts, systemic levels of TMAO were observed to strongly associate with type 2 diabetes. In addition, circulating TMAO levels were associated with obesity traits in the different inbred strains represented in the Hybrid Mouse Diversity Panel. Further, antisense oligonucleotide-mediated knockdown or genetic deletion of the TMAO-producing enzyme, flavin-containing monooxygenase 3 (FMO3), conferred protection against obesity in mice. Complimentary mouse and human studies indicate a negative regulatory role for FMO3 in the beiging of white adipose tissue. Collectively, our studies reveal a link between the TMAO-producing enzyme FMO3 and obesity and the beiging of white adipose tissue.

IKKβ functions in smooth muscle cells to regulate vascular inflammatory responses and atherosclerosis development.

These results position as an underappreciated regulator of inflammation initiation and resolution, and suggest that endogenously synthesized arachidonic acid and eicosapentaenoic acid are key determinates of inflammatory disease progression and liver X receptor signaling.

Background & Aims:The most prescribed non-nucleoside reverse transcriptase inhibitor efavirenz has been associated with elevated risk for dyslipidemia and hepatic steatosis in HIVinfected patients but the underlying mechanisms remain elusive. Here we investigated the role of pregnane X receptor (PXR) in mediating the adverse effects of efavirenz on lipid homeostasis.Methods: Cell-based reporter assays, primary cell culture, and multiple mouse models including conditional knockout and humanized mice were combined to study the impact of efavirenz on PXR activities and lipid homeostasis in vitro and in vivo. A novel liver-specific PXR knockout mouse model was also generated to determine the contribution of hepatic PXR signaling to efavirenz-elicited dyslipidemia and hepatic steatosis. Results:We found that efavirenz is a potent PXR-selective agonist that can efficiently activate PXR and induce its target gene expression in vitro and in vivo. Treatment with efavirenz induced hypercholesterolemia and hepatic steatosis in mice but deficiency of hepatic PXR abolished these adverse effects. Interestingly, efavirenz-mediated PXR activation regulated the expression of several key hepatic lipogenic genes including fatty acid transporter CD36 and cholesterol biosynthesis enzyme squalene epoxidase (SQLE), leading to increased lipid uptake and cholesterol biosynthesis in hepatic cells. While CD36 is a known PXR target gene, we identified a DR-2-type of PXR-response element in the SQLE promoter and established SQLE as a direct transcriptional

Objective Inflammatory responses are the driving force of atherosclerosis development. IκB kinase β (IKKβ), a central coordinator in inflammation through regulation of nuclear factor-κB, has been implicated in the pathogenesis of atherosclerosis. Macrophages play an essential role in the initiation and progression of atherosclerosis, yet the role of macrophage IKKβ in atherosclerosis remains elusive and controversial. This study aims to investigate the impact of IKKβ expression on macrophage functions and to assess the effect of myeloid-specific IKKβ deletion on atherosclerosis development. Methods and Results To explore the issue of macrophage IKKβ involvement of atherogenesis, we generated myeloid-specific IKKβ-deficient low-density lipoprotein receptor–deficient mice (IKKβΔMyeLDLR−/−). Deficiency of IKKβ in myeloid cells did not affect plasma lipid levels but significantly decreased diet-induced atherosclerotic lesion areas in the aortic root, brachiocephalic artery, and aortic arch of low-density lipoprotein receptor–deficient mice. Ablation of myeloid IKKβ attenuated macrophage inflammatory responses and decreased atherosclerotic lesional inflammation. Furthermore, deficiency of IKKβ decreased adhesion, migration, and lipid uptake in macrophages. Conclusion The present study demonstrates a pivotal role for myeloid IKKβ expression in atherosclerosis by modulating macrophage functions involved in atherogenesis. These results suggest that inhibiting nuclear factor-κB activation in macrophages may represent a feasible approach to combat atherosclerosis.

BackgroundBisphenol A (BPA) is a base chemical used extensively in many consumer products. BPA has recently been associated with increased risk of cardiovascular disease (CVD) in multiple large‐scale human population studies, but the underlying mechanisms remain elusive. We previously reported that BPA activates the pregnane X receptor (PXR), which acts as a xenobiotic sensor to regulate xenobiotic metabolism and has pro‐atherogenic effects in animal models upon activation. Interestingly, BPA is a potent agonist of human PXR but does not activate mouse or rat PXR signaling, which confounds the use of rodent models to evaluate mechanisms of BPA‐mediated CVD risk. This study aimed to investigate the atherogenic mechanism of BPA using a PXR‐humanized mouse model.Methods and ResultsA PXR‐humanized ApoE deficient (huPXR•ApoE−/−) mouse line was generated that respond to human PXR ligands and feeding studies were performed to determine the effects of BPA exposure on atherosclerosis development. Exposure to BPA significantly increased atherosclerotic lesion area in the aortic root and brachiocephalic artery of huPXR•ApoE−/− mice by 104% (P<0.001) and 120% (P<0.05), respectively. By contrast, BPA did not affect atherosclerosis development in the control littermates without human PXR. BPA exposure did not affect plasma lipid levels but increased CD36 expression and lipid accumulation in macrophages of huPXR•ApoE−/− mice.ConclusionThese findings identify a molecular mechanism that could link BPA exposure to increased risk of CVD in exposed individuals. PXR is therefore a relevant target for future risk assessment of BPA and related environmental chemicals in humans.

Heat shock protein 70 (Hsp70) is well documented to possess general cytoprotective properties in protecting the cell against stressful and noxious stimuli. We have recently shown that expression of the stress-inducible Hsp70.3 gene in the myocardium in response to ischemic preconditioning is NF-B-dependent and necessary for the resulting late phase cardioprotection against a subsequent ischemia/reperfusion injury. Here we show that the Hsp70.3 gene product is subject to post-transcriptional regulation through parallel regulatory processes involving microRNAs and alternative polyadenylation of the mRNA transcript. First, we show that cardiac ischemic preconditioning of the in vivo mouse heart results in decreased levels of two Hsp70.3-targeting microRNAs: miR-378* and miR-711. Furthermore, an ischemic or heat shock stimulus induces alternative polyadenylation of the expressed Hsp70.3 transcript that results in the accumulation of transcripts with a shortened 3 -UTR. This shortening of the 3 -UTR results in the loss of the binding site for the suppressive miR-378* and thus renders the alternatively polyadenylated transcript insusceptible to miR-378*-mediated suppression. Results also suggest that the alternative polyadenylation-mediated shortening of the Hsp70.3 3 -UTR relieves translational suppression observed in the long 3 -UTR variant, allowing for a more robust increase in protein expression. These results demonstrate alternative polyadenylation of Hsp70.3 in parallel with ischemic or heat shock-induced up-regulation of mRNA levels and implicate the importance of this process in post-transcriptional control of Hsp70.3 expression.Heat shock (HS) 3 and the subsequent expression of heat shock proteins have long been known to possess cytoprotective properties and provide cardioprotection against ischemia/reperfusion (I/R) injury (1-3). The Hsp70 family is among the best studied of the heat shock proteins, has been shown to be induced by many cardiac preconditioning stimuli, and plays a necessary role in the second window of protection (3-6). Hsp70.1 and Hsp70.3 are two nearly identical stress-inducible Hsp70 genes present in the murine heart. The two protein products differ by only a single amino acid, but curiously, the sequence of the two genes is divergent in the regulatory regions of the gene promoter (beyond the first 270 amino acids proximal to the transcriptional start site) and within the 3Ј-untranslated region (3Ј-UTR) of the mRNA transcript. Historically, these two genes are considered to be functionally redundant.We have recently shown that NF-B-dependent expression of heat shock protein 70.3 (Hsp70.3), but not the closely related Hsp70.1, is necessary for the late phase or second window of ischemic preconditioning (IPC) cardioprotection against acute I/R in the heart (6). In fact, Hsp70.3 and Hsp70.1 appear to contribute differing functions to cell survival in the myocardium (6, 7). Thus, it is important to understand the regulation of these two genes independently. We previously reported that NF-B in...