MBOAT7-driven lysophosphatidylinositol acylation in adipocytes contributes to systemic glucose homeostasis - PubMed (original) (raw)

doi: 10.1016/j.jlr.2023.100349. Epub 2023 Feb 18.

Venkateshwari Varadharajan 1, Rakhee Banerjee 1, Amanda L Brown 1, Anthony J Horak 1, Rachel C Hohe 1, Bryan M Jung 1, Yunguang Qiu 2, E Ricky Chan 3, Calvin Pan 4, Renliang Zhang 5, Daniela S Allende 6, Belinda Willard 5, Feixiong Cheng 2, Aldons J Lusis 4, J Mark Brown 7

Affiliations

MBOAT7-driven lysophosphatidylinositol acylation in adipocytes contributes to systemic glucose homeostasis

William J Massey et al. J Lipid Res. 2023 Apr.

Abstract

We previously demonstrated that antisense oligonucleotide-mediated knockdown of Mboat7, the gene encoding membrane bound O-acyltransferase 7, in the liver and adipose tissue of mice promoted high fat diet-induced hepatic steatosis, hyperinsulinemia, and systemic insulin resistance. Thereafter, other groups showed that hepatocyte-specific genetic deletion of Mboat7 promoted striking fatty liver and NAFLD progression in mice but does not alter insulin sensitivity, suggesting the potential for cell autonomous roles. Here, we show that MBOAT7 function in adipocytes contributes to diet-induced metabolic disturbances including hyperinsulinemia and systemic insulin resistance. We generated Mboat7 floxed mice and created hepatocyte- and adipocyte-specific Mboat7 knockout mice using Cre-recombinase mice under the control of the albumin and adiponectin promoter, respectively. Here, we show that MBOAT7 function in adipocytes contributes to diet-induced metabolic disturbances including hyperinsulinemia and systemic insulin resistance. The expression of Mboat7 in white adipose tissue closely correlates with diet-induced obesity across a panel of ∼100 inbred strains of mice fed a high fat/high sucrose diet. Moreover, we found that adipocyte-specific genetic deletion of Mboat7 is sufficient to promote hyperinsulinemia, systemic insulin resistance, and mild fatty liver. Unlike in the liver, where Mboat7 plays a relatively minor role in maintaining arachidonic acid-containing PI pools, Mboat7 is the major source of arachidonic acid-containing PI pools in adipose tissue. Our data demonstrate that MBOAT7 is a critical regulator of adipose tissue PI homeostasis, and adipocyte MBOAT7-driven PI biosynthesis is closely linked to hyperinsulinemia and insulin resistance in mice.

Keywords: acyltransferase; arachidonic acid; diabetes; hepatocytes; hyperinsulinemia; metabolism; non-alcoholic fatty liver disease; obesity; phosphatidylinositol biosynthesis; systemic insulin resistance.

Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.

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Conflict of interest statement

Conflict of interest Dr. Daniela Allende reports serving as an Advisory Board Member for Incyte Corporation. All other authors declare no competing financial interests related to this work.

Figures

Fig. 1

Fig. 1

Mboat7 Expression in White Adipose Tissue is Correlated with Adiposity in mice. We used a systems genetics approach to examine links between Mboat7 expression and metabolic traits in mice from the hybrid mouse diversity panel (HMDP). To induce obesity, all mouse strains represented in the HMDP were fed an obesity-promoting high fat and high sucrose diet. Across the different strains in the HMDP, the expression (RMA, Robust Multi-Array Average) of Mboat7 in adipose tissue has a strong negatively correlated with gonadal (A), subcutaneous (B), and retroperitoneal (C) white adipose tissue mass in females. There is a similar negative correlation in male (D) retroperitoneal adipose tissue. MBOAT7, membrane bound O-acyltransferase 7.

Fig. 2

Fig. 2

Adipocyte-Specific Mboat7 Deletion (Mboat7 ASKO) Promotes Mild Fatty Liver. Male control (Mboat7 fl/fl) or adipocyte-specific Mboat7 knockout mice (Mboat7 ASKO) were fed chow or high fat diet (HFD) for 20 weeks and metabolically phenotyped. A: Western blots from tissues collected from age-matched, chow fed Mboat7 fl/fl or Mboat7 ASKO mice. B–M: Gonadal white adipose tissue (gWAT), lysophosphatidylinositol (LPI), (B) and phosphatidylinositol (PI) species, including the MBOAT7 product PI-38:4 (C) and others (D) were quantified via LC-MSin Mboat7 fl/fl or Mboat7 ASKO mice were fed chow or high fat diet (HFD) for 20-week (n = 5–7; ∗∗∗∗P ≤ 0.0001; Two-way (C) or Three-way (B, D) ANOVA with Tukey’s post hoc test). E: Representative liver H&E stained sections. 10× magnification (scale bar = 200 μm). F: Liver weight measurements from Mboat7 fl/fl or Mboat7 ASKO mice fed Chow and HFD for 20 weeks (n = 6–8; Two-way ANOVA with Tukey’s post hoc test). G: Percent steatosis was quantified by a blinded pathologist (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). Hepatic triglycerides (H) and hepatic esterified cholesterol (I) were measured enzymatically (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). J: Representative gWAT H&E stained sections. 10× magnification (scale bar = 200 μm). K: Body weight was measured weekly. Percent fat (L) and % Lean (M) mass were determined via echo-MRI after 8 weeks of chow or HFD in Mboat7 fl/fl or Mboat7 ASKO mice (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). All data are presented as mean ± S.D.

Fig. 3

Fig. 3

Adipocyte-Specific Mboat7 Deletion (Mboat7 ASKO) Promotes Glucose Intolerance, Hyperinsulinemia, and Peripheral Insulin Resistance. A–C: Male control (Mboat7 fl/fl) or adipocyte-specific Mboat7 knockout mice (Mboat7 ASKO) were fed a chow or HFD for 12 weeks and then underwent an intraperitoneal glucose tolerance test (GTT). A: Plasma glucose levels were measured (in duplicate or triplicate at each time point) throughout the GTT (n = 5–7; Three-way ANOVA with Tukey’s post hoc test). B: The area under the curve was calculated for each mouse throughout the GTT (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). C: Fasting blood glucose was measured after a 4-h fast (time = 0 min for GTT) (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). D: Fasting plasma insulin was measured in Mboat7 fl/fl or Mboat7 ASKO mice that were fed a chow or HFD for 20 weeks (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). E–L: Male control (Mboat7 fl/fl) or adipocyte-specific Mboat7 knockout mice (Mboat7 ASKO) were fed HFD for 12–13 weeks, underwent surgery for catheterization of carotid artery and a jugular vein, and were subjected to euglycemic-hyperinsulinemic clamping. E: Plasma glucose levels were measured throughout the clamp (n = 6–9; Two-way ANOVA with Bonferroni’s post hoc test). F: Glucose infusion rates (GIRs) were measured throughout the clamp (n = 6–9; Two-way ANOVA with Bonferroni’s post hoc test). G: Steady state glucose infusion rate was calculated by averaging GIRs from 80 to 120 min (n = 6–9; Student’s t test). H: Plasma glucose levels were determined by averaging the −10 and 0 min time points (n = 6–9; Student’s t test). I: The rate of glucose disappearance (Rd) was calculated for animals in the fasting state by averaging the Rd from −10 and 0 min time points and the clamped state by averaging Rd from 80 to 120 min (n = 6–9; Two-way ANOVA with Bonferroni’s post hoc test). J: Fold glucose disappearance was calculated by dividing clamp Rd by fasting Rd (n = 6–9; Student’s t test). Tissue specific uptake was measured in gonadal (K) and subcutaneous (L) white adipose tissue (n = 6–9; Student’s t test).

Fig. 4

Fig. 4

Adipocyte-Specific Mboat7 Deletion (Mboat7 ASKO) Reorganizes White Adipose Tissue Gene Expression and Circulating Adipokine Levels. Male control (Mboat7 fl/fl) or adipocyte-specific Mboat7 knockout mice (Mboat7 ASKO) were fed chow or high fat diet (HFD) for 20-week. A: gWAT weight measurements from Mboat7 fl/fl or Mboat7 ASKO mice fed Chow and HFD for 20 weeks (n = 6–8; Two-way ANOVA with Tukey’s post hoc test). B: Plasma Leptin was measured in Mboat7 fl/fl or Mboat7 ASKO mice that were fed a chow or HFD for 20 weeks (n = 5–7; Two-way ANOVA with Tukey’s post hoc test). To assess β3–adrenergic stimulated lipolysis, plasma nonesterified fatty acids (NEFA), (C) and glycerol (D) were measured in Mboat7 fl/fl or Mboat7 ASKO mice fed a chow or HFD for 11 weeks 15 min after saline or CL316,243 injection (n = 2–5/group; Three-way ANOVA with Tukey’s post hoc test). E–G: gWAT RNA was used for RNA-sequencing from Mboat7 fl/fl or Mboat7 ASKO mice that were fed a chow or HFD for 20 weeks. E: Groups clustered primarily based on the diet by principal component analysis (n = 4/group). F: A Volcano plot of transcripts was used to determine differentially expressed genes (DEGs) in Mboat7 fl/fl or Mboat7 ASKO mice that were fed an HFD for 20 weeks. Plot summarizes log2 fold changes versus significance in response to Mboat7 inhibition (n = 4/group; genes with q-val < 0.05 and fold change > |0.5| were considered significantly differentially expressed). G: Row-normalized expression for the top 20 up and downregulated DEGs that reached a _P_-value <0.05 are shown by heat map in Mboat7 fl/fl or Mboat7 ASKO mice that were fed an HFD for 20 weeks. H: gWAT stromal vascular fraction was subjected to flow cytometry analysis of macrophage subpopulations. I, J: Correlation between gWAT macrophage subsets and body weight. All data are presented as mean ± S.D. unless otherwise noted.

Fig. 5

Fig. 5

LPI-18:1 Induces Acute Signaling Events Associated with Insulin Action in Adipose Tissue of Mboat7 ASKO mice. A: Volcano plot of phosphopeptides upregulated and downregulated in gonadal white adipose tissue (gWAT) of Mboat7 ASKO mice. Phosphopeptides determined to be |log2FoldChange| >0.5 different in the LPI and saline samples with a _P_-value <0.05 (two-tailed t test) were considered significantly differentially phosphorylated. (Average of n = 4/group; pink dots represent significantly upregulated phospho-peptides, green dots represent significantly downregulated phospho-peptides; and purple dots represent insulin resistance-associated phosphopeptides that are significantly different). B, C: KEGG pathway analysis of significantly differentially phosphorylated peptides. KEGG, Kyoto Encyclopedia of Genes and Genomes; LPI, lysophosphatidylinositol; _Mboat7_ASKO, Mboat7 adipocyte-specific knockout mice.

References

    1. Cohen J.C., Horton J.D., Hobbs H.H. Human fatty liver disease: old questions and new insights. Science. 2011;332:1519–1523. - PMC - PubMed
    1. Wree A., Broderick L., Canbay A., Hoffman H.M., Feldstein A.E. From NAFLD to NASH to cirrhosis-new insights into disease mechanisms. Nat. Rev. Gastroenterol. Hepatol. 2013;10:627–636. - PubMed
    1. Rinella M.E., Sanyal A.J. Management of NAFLD: a stage-based approach. Nat. Rev. Gastroenterol. Hepatol. 2016;13:196–205. - PubMed
    1. Sarwar R., Pierce N., Koppe S. Obesity and nonalcoholic fatty liver disease: current perspectives. Diabetes Metab. Syndr. Obes. 2018;11:533–542. - PMC - PubMed
    1. Mancina R.M., Dongiovanni P., Petta S., Pingitore P., Meroni M., Rametta R., et al. The MBOAT7-TMC4 variant rs641738 increases risk of nonalcoholic fatty liver disease in individuals of European descent. Gastroenterology. 2016;150:1219–1230. - PMC - PubMed

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