Overexpression of Jazf1 reduces body weight gain and regulates lipid metabolism in high fat diet

https://doi.org/10.1016/j.bbrc.2013.12.094Get rights and content

Highlights

  • The expression of Jazf1 in the liver suppressed lipid accumulation.

  • Jazf1 significantly increases transcription of fatty acid synthase.

  • Jazf1 plays a critical role in the regulation of energy and lipid homeostasis.

  • Jazf1 associates the development of metabolic disorder.

  • Jazf1 may provide a new therapeutic target in the management of metabolic disorder.

Abstract

Jazf1 is a 27 kDa nuclear protein containing three putative zinc finger motifs that is associated with diabetes mellitus and prostate cancer; however, little is known about the role that this gene plays in regulation of metabolism. Recent evidence indicates that Jazf1 transcription factors bind to the nuclear orphan receptor TR4. This receptor regulates PEPCK, the key enzyme involved in gluconeogenesis. To elucidate Jazf1’s role in metabolism, we fed a 60% fat diet for up to 15 weeks. In Jazf1 overexpression mice, weight gain was found to be significantly decreased. The expression of Jazf1 in the liver also suppressed lipid accumulation and decreased droplet size. These results suggest that Jazf1 plays a critical role in the regulation of lipid homeostasis. Finally, Jazf1 may provide a new therapeutic target in the management of obesity and diabetes.

Introduction

Lipid metabolism is separated into lipogenesis and lipolysis. Lipogenesis is the process by which acetyl-CoA is converted to fats. Lipogenesis related genes typically include SREBP1-c, FAS and ACC. SREBP1-c is a critical regulator of extension of lipid storage in liver [1], as well as an important factor in transcriptional regulation of the fatty acid synthetic genes, FAS and ACC [2]. FAS is an enzyme that catalyzes fatty acid synthesis via the production of palmitate from acetyl-CoA and malonyl-CoA [3]. Similarly, ACC, which synthesizes malonyl-CoA from acetyl-CoA, is an important enzyme in triglyceride biosynthesis. ACC is predominantly expressed in the lipogenesis related tissues, liver and adipose [4]. Lipolysis is the breakdown of lipids. HSL and ATGL are important lipolysis related genes. HSL is an intracellular lipase that is capable of hydrolyzing stored triglycerides to free fatty acids in adipose tissue [5]. ATGL initiates the breakdown of intracellular triglycerides into fatty acid monomers in adipose tissue [6]. An imbalance between lipogenesis and lipolysis is caused by abnormal lipid metabolism (dyslipidemia), and obesity is a major element leading to the development of dyslipidemia [7].

Obesity is caused by poor diet, especially excess energy intake. Obesity is also the major pathological factor that predisposes individuals to insulin resistance [8], [9], which is the central feature of metabolic syndrome, whereby target tissues fail to respond efficiently to normal concentrations of insulin [10].

TR4 belongs to a subclass of orphan nuclear receptors. TR4 is highly expressed in several tissues, including the testis, brain, kidney, liver, and adipose tissue. Although the precise physiological functions of TR4 remain poorly understood [11], recent reports suggest that certain fatty acids and eicosanoids bind to and enhance the transcriptional activity of TR4, suggesting that TR4 might function as a lipid sensor [12]. Other studies have provided evidence of a role of TR4 in lipid metabolism and gluconeogenesis [13], [14]. TR4 also regulates various genes in diverse pathways, including apoE, Gata1, PEPCK, and CD36 [15], [16], [17].

PEPCK is the key enzyme controlling the rate of gluconeogenesis based on its expression levels. PEPCK is mainly expressed in the liver and kidney, where it participates in gluconeogenesis and glyceroneogenesis [18]. PEPCK activity can be controlled at the transcriptional level in response to nutritional conditions. A recent study found that genes involved in the gluconeogenic pathway in response to energy expenditure and storage, including PEPCK, exhibit a rhythmicity in their mRNA levels and their corresponding regulatory hormones and/or transcriptional regulators [19].

Jazf1, a protein with unknown function, is a basic protein with a molecular mass of 27.1 kDa that contains three putative zinc finger motifs [20]. Variants of Jazf1 are associated with an increased risk of prostate cancer, an increased risk of diabetes, and an increased height [21]. This gene encodes a nuclear protein with three C2H2-type zinc fingers and functions as a transcriptional repressor. Chromosomal aberrations involving this gene are associated with endometrial stromal tumors. Alternatively spliced variants that encode different protein isoforms have been described; however, not all variants have been fully characterized. A recent study indicated that Jazf1 acts as a strong repressor of DR1-dependent transcriptional activation by the TR4 [22]. Jazf1 interacts specifically with the ligand-binding domain of TR4 and functions as a TR4-selective cofactor that may play an important role in mediating transcriptional repression by TR4 [22].

In this study, we focused on the role of Jazf1 in lipid metabolism in a Jazf1 over-expression transgenic mouse model. Specifically, we generated TG mice to elucidate the function of the Jazf1 gene in lipid metabolism.

Section snippets

Generation of transgenic mice and experimental protocol

The Jazf1 ORF, 13.5-day post-coitus embryo cDNA, was subcloned into the pEGFP-N1 vector (Clontech). The plasmid DNA for microinjection was purified using a Plasmid Midi Kit (Qiagen). The expression cassette was prepared by digesting the recombinant vector DNA with DraIII. Fertilized one-cell embryos were obtained from BDF1 females. A DNA cassette was purified by dialysis in Tris/EDTA (TE, pH 8.0) and microinjected into the pronuclei of fertilized embryos. Injected embryos were cultured for 20 h

Jazf1 inhibited PEPCK activity via TR4

Jazf1, TR4 and PEPCK are mainly expressed in metabolic tissue, such as liver and adipose tissue. Therefore, the mRNA expression levels and protein expression levels of these genes were compared in liver and adipose tissue from TG and WT mice. PCR was conducted to examine mRNA expression levels of Jazf1, TR4 and PEPCK in liver from WT and TG mice. The results of PCR revealed no difference in TR4 mRNA expression in liver from WT and TG. This repression of TR4 was probably made by the binding of

Discussion

This study demonstrated that Jazf1 regulated activation of PEPCK and decreased lipid accumulation and lipid droplet size. In a previous study, Jazf1-overexpressing transgenic mice (TG) that express mouse Jazf1 cDNA under the control of the CMV promoter were generated [2]. Moreover, a recent study showed that overexpression of Jazf1 in adipocytes and hepatocytes led to reduced lipogenesis and increased lipolysis [25]. In addition, genome-wide association studies have verified associations

Acknowledgments

This research was supported by the Next-Generation BioGreen21 Program (NO. PJ 009573), the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (NO. 2008-0062618).

References (31)

  • S. Guerra et al.

    Hemodynamics assessed via approximate entropy analysis of impedance cardiography time series: effect of metabolic syndrome

    Am. J. Physiol. Heart Circ. Physiol.

    (2011)
  • B.B. Kahn et al.

    Obesity and insulin resistance

    J. Clin. Invest.

    (2000)
  • M. Barton et al.

    Obesity and risk of vascular disease: importance of endothelium-dependent vasoconstriction

    Br. J. Pharmacol.

    (2012)
  • L.H. Opie

    Metabolic syndrome

    Circulation

    (2007)
  • Y. Zhang et al.

    Loss of testicular orphan receptor 4 impairs normal myelination in mouse forebrain

    Mol. Endocrinol.

    (2007)
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