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. 2019 Mar 5;116(10):4285-4290.
doi: 10.1073/pnas.1815150116. Epub 2019 Feb 15.

PGC1A regulates the IRS1:IRS2 ratio during fasting to influence hepatic metabolism downstream of insulin

Aurèle Besse-Patin  1   2 , Stewart Jeromson  1   3 , Philipa Levesque-Damphousse  1   2 , Blandine Secco  4 , Mathieu Laplante  4   5 , Jennifer L Estall  6   2   3
Affiliations

PGC1A regulates the IRS1:IRS2 ratio during fasting to influence hepatic metabolism downstream of insulin

Aurèle Besse-Patin et al. Proc Natl Acad Sci U S A. .

Abstract

Precise modulation of hepatic glucose metabolism is crucial during the fasting and feeding cycle and is controlled by the actions of circulating insulin and glucagon. The insulin-signaling pathway requires insulin receptor substrate 1 (IRS1) and IRS2, which are found to be dysregulated in diabetes and obesity. The peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1A) is a fasting-induced transcriptional coactivator. In nonalcoholic fatty liver disease and in patients with type 2 diabetes, low hepatic PGC1A levels are associated with insulin resistance. However, how PGC1A activity impacts the hepatic insulin-signaling pathway is still unclear. We used gain- and loss-of-function models in mouse primary hepatocytes and measured hepatocyte insulin response by gene and protein expression and ex vivo glucose production. We found that the PGC1A level determines the relative ratio of IRS1 and IRS2 in hepatocytes, impacting insulin receptor signaling via protein kinase B/AKT (AKT). PGC1A drove the expression of IRS2 downstream of glucagon signaling while simultaneously reducing IRS1 expression. We illustrate that glucagon- or PGC1A-induced IRS2 expression was dependent on cAMP Response Element Binding Protein activity and that this was essential for suppression of hepatocyte gluconeogenesis in response to insulin in vitro. We also show that increased hepatic PGC1A improves glucose homeostasis in vivo, revealing a counterregulatory role for PGC1A in repressing uncontrolled glucose production in response to insulin signaling. These data highlight a mechanism by which PGC1A plays dual roles in the control of gluconeogenesis during the fasting-to-fed transition through regulated balance between IRS1 and IRS2 expression.

Keywords: PGC-1; Ppargc1a; fasting; gluconeogenesis; liver.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
PGC1A levels influence insulin-stimulated AKT phosphorylation. Immunoblots of protein from primary mouse hepatocytes treated with 100 nM insulin for 15 min (or indicated time). Insulin-signaling pathway activation in hepatocytes from (A and D) male WT and LH (liver-PGC1A heterozygote) and LKO (liver-PGC1A knockout) mice. (B and E) Hepatocytes infected with adenoviruses expressing vector control (AdCTL) or PGC1A or (C) liver-specific PGC1A and PGC1B double-knockout mice (LA/BKO). All experiments were performed at least two times, and each lane represents an individual mouse.
Fig. 2.
Fig. 2.
PGC1A levels affect gene expression of key members of the insulin-signaling pathway. Gene expression by qPCR in primary mouse hepatocytes. WT cells infected with adenovirus overexpressing (A) PGC1A, (B) PGC1B, or (C) primary hepatocytes isolated from LA/BKO mice. Experiments were performed at least twice with n = 4 ± SEM *P < 0.05 vs. control.
Fig. 3.
Fig. 3.
PGC1A regulates IRS protein expression. Immunoblots of protein from primary hepatocytes treated 15 min with 100 nM insulin. (A) Cells overexpressing vector control (CTL), PGC1A, or PGC1B. (B) Cells from LA/BKO mice. (C) Ratio of p-AKT to t-AKT in cells overexpressing PGC1A or PGC1B (n = 4 ± SEM, performed at least two times).
Fig. 4.
Fig. 4.
PGC1A potentiates glucagon-stimulated IRS2 expression through CREB. Primary mouse hepatocytes treated with 40 nM glucagon or vehicle. (A) Gene expression (n = 4 ± SE) and (B) immunoblots from cells expressing shControl or shPGC1A. (B, Right) Quantification of two experiments (n = 5 ± SEM). (C) Immunoblot from hepatocytes coexpressing vector control (CTL) or dominant-negative CREB (C-DN or CREBDN), dominant-negative TCF4 (T-DN or TCF4DN), or PGC1A, as indicated. (Right) Quantification of two experiments (n = 5 ± SEM). (D) mRNA in primary hepatocytes expressing CREB DN or Control vector. (E) Immunoblots from primary hepatocytes pretreated or not with glucagon (40 nM, 4 h) and treated with insulin (100 nM, 15 min). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 vs. control. Blots are representative of two independent experiments. A.U., arbitrary units; Glg, glucagon; veh, vehicle.
Fig. 5.
Fig. 5.
Insulin-induced suppression of hepatocyte gluconeogenesis is regulated by the PGC1A/IRS2 axis in vitro and in vivo. (A) Insulin-mediated (100 nM, 1 h) suppression of glucagon-induced (1 nM, 1 h) gluconeogenesis (GNG) in primary hepatocytes overexpressing vector, IRS1, or IRS2 (n = 8 ± SEM). *P < 0.05 vs. Control; #P < 0.05 IRS2 vs. IRS1. (B) Insulin suppression of GNG in WT and LA/BKO hepatocytes expressing control or PGC1A and shControl or shIRS2, as indicated (n = 4 ± SEM). ###P < 0.001 vs. WT; *P < 0.05, ***P < 0.001. Male mice tail-vein–injected with viruses encoding vector (AdCTL) or PGC1A (AdPGC1A). Blood glucose (C) and plasma insulin (D) measured after 16 h fasting or 1 h refeeding. (E) Pyruvate tolerance test and area under the curve (Right). n = 9 ± SEM; *P < 0.05 vs. control. All experiments were performed twice.
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References

    1. Moore MC, Coate KC, Winnick JJ, An Z, Cherrington AD. Regulation of hepatic glucose uptake and storage in vivo. Adv Nutr. 2012;3:286–294. - PMC - PubMed
    1. Haeusler RA, McGraw TE, Accili D. Biochemical and cellular properties of insulin receptor signalling. Nat Rev Mol Cell Biol. 2018;19:31–44. - PMC - PubMed
    1. Petersen MC, Shulman GI. Mechanisms of insulin action and insulin resistance. Physiol Rev. 2018;98:2133–2223. - PMC - PubMed
    1. Scarpulla RC. Transcriptional paradigms in mammalian mitochondrial biogenesis and function. Physiol Rev. 2008;88:611–638. - PubMed
    1. Yoon JC, et al. Control of hepatic gluconeogenesis through the transcriptional coactivator PGC-1. Nature. 2001;413:131–138. - PubMed

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