Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 32 (5), 2630-2643

FGF21 Induced by Carbon Monoxide Mediates Metabolic Homeostasis via the PERK/ATF4 Pathway

Affiliations

FGF21 Induced by Carbon Monoxide Mediates Metabolic Homeostasis via the PERK/ATF4 Pathway

Yeonsoo Joe et al. FASEB J.

Abstract

The prevalence of metabolic diseases, including type 2 diabetes, obesity, and cardiovascular disease, has rapidly increased, yet the molecular mechanisms underlying the metabolic syndrome, a primary risk factor, remain incompletely understood. The small, gaseous molecule carbon monoxide (CO) has well-known anti-inflammatory, antiproliferative, and antiapoptotic effects in a variety of cellular- and tissue-injury models, whereas its potential effects on the complex pathways of metabolic disease remain unknown. We demonstrate here that CO can alleviate metabolic dysfunction in vivo and in vitro. We show that CO increased the expression and section of the fibroblast growth factor 21 (FGF21) in hepatocytes and liver. CO-stimulated PERK activation and enhanced the levels of FGF21 via the eIF2α-ATF4 signaling pathway. The induction of FGF21 by CO attenuated endoreticulum stress- or diet-induced, obesity-dependent hepatic steatosis. Moreover, CO inhalation lowered blood glucose levels, enhanced insulin sensitivity, and promoted energy expenditure by stimulating the emergence of beige adipose cells from white adipose cells. In conclusion, we suggest that CO acts as a potent inducer of FGF21 expression and that CO critically depends on FGF21 to regulate metabolic homeostasis.-Joe, Y., Kim, S., Kim, H. J., Park, J., Chen, Y., Park, H.-J., Jekal, S.-J., Ryter, S. W., Kim, U. H., Chung, H. T. FGF21 induced by carbon monoxide mediates metabolic homeostasis via the PERK/ATF4 pathway.

Keywords: ER stress; ROS; hepatic steatosis; metabolic disease; thermogenic genes.

Conflict of interest statement

This work was supported by Priority Research Centers Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (Grant 2014R1A6A1030318) and the Bio and Medical Technology Development Program of the NRF, funded by the Ministry of Science, Information and Communications Technology (ICT), and Future Planning (Grants 2012M3A9C3048687 to H.T.C., and NRF-2012R1A3A2026453 to U.H.K). The authors declare no conflicts of interest.

Figures

Figure 1.
Figure 1.
The protective effects of CO on HFD-induced metabolic syndrome are mediated by FGF21. A, B) Male, 6-wk-old C57BL/6 mice (6 mice/group) were fed an NCD or HFD for 16 wk. After 8 wk, animals were subjected to inhaled CO (250 ppm) for 2 h/d for 8 wk. The average body weight of Fgf21+/+ (A) and Fgf21−/− (B) mice was measured every 2 d. C, D) GTT (C) and ITT (D) were determined after 16 wk of NCD and HFD feeding. E) H&E staining of liver tissues was performed in Fgf21+/+ and Fgf21−/− mice. Scale bars, 50 μm. FI) Liver weight (F), triglyceride (G), serum ALT (H), and AST (I) levels were investigated after 16 wk of NCD and HFD feeding. Data are presented as means ± sem (n = 6). NS, not significant. **P < 0.01, ***P < 0.001.
Figure 2.
Figure 2.
CO enhances the expression of FGF21 via ROS production. A, B) AML12 cells were treated with CORM2 (20 μM) for various times (0, 0.5, 1, 3, and 6 h), and then, the FGF21 mRNA levels were measured by RT-PCR (A) and qRT-PCR (B). C) AML12 cells were transfected with scRNA and siRNA against Fgf21, followed by the administration of CORM2 (20 μM) for 0.5 and 1 h. D, E) AML12 cells were pretreated with MitoTEMPO (100 μM) for 1 h, and then, cells were treated with CORM2 (20 μM) for another 2 h. Then, the mRNA expression of FGF21 was determined by RT-PCR (D) and qRT-PCR (E). F, G) AML12 cells were pretreated with NAC (3 mM) for 30 min, followed by the administration of CORM2 (20 μM) for another 2 h. Then, the mRNA expression of FGF21 was detected by RT-PCR (F) and qRT-PCR (G). H) To assess the production of mtROS, AML12 cells were pretreated with NAC (3 mM) for 30 min and MitoTEMPO (100 μM) for 1 h, and then were treated with CORM2 (20 μM) for another 2 h. mtROS was detected with MitoSOX Red (5 μM) for 50 min and measured by flow cytometry. Rotenone (10 μM) was used as a positive control for mtROS production. Data are presented as means ± sem (n = 3). NS, not significant. *P < 0.05, **P < 0.01, ***P < 0.001.
Figure 3.
Figure 3.
The expression of FGF21 regulated by CO is mediated by PERK signaling pathway. A, B) MEF cells from Perk+/+ and Perk−/− mice were treated with CORM2 (20 μM) for 1 and 3 h. Then, FGF21 mRNA expression was determined by RT-PCR (A). Perk+/+ and Perk−/− MEF cells were treated with CORM2 at various concentrations (0, 20, and 40 μM) for 3 h, and the mRNA level of FGF21 was measured by qRT-PCR (B). C) AML12 cells were transfected with scRNA and siRNA against Perk, and then, cells were treated with CORM2 (20 μM) for 3 h. mRNA levels of FGF21 and PERK were detected by RT-PCR. DF) Heterozygous eIF2αS/A/fTg mice and eIF2A/A mutant mice were administrated CORM-2 for 3 h or CO gas (250 ppm) for 2 h. Serum FGF21 levels were assessed by ELISA (D), and mRNA levels in liver tissues were assessed by RT-PCR (E) and qRT-PCR (F). G) Primary hepatocytes isolated from heterozygous eIF2αS/A/fTg mice and eIF2A/A mutant mice were treated with CO gas for 2 h, and the mRNA level of FGF21 was detected by qRT-PCR. HJ) Hepatocytes from Atf4+/+, Atf4−/−, Ire1+/+, Ire1−/−, Atf6+/+, and Atf6−/− mice were treated with CORM2 or RuCl2 as a control for ruthenium for 3 h to assess the mRNA expression of FGF21 by RT-PCR. Data are presented as means ± sem (n = 3). NS, not significant. **P < 0.01, ***P < 0.001.
Figure 4.
Figure 4.
CO protects against ER stress-induced hepatic steatosis by induction of FGF21 expression. A) 6-wk-old Fgf21+/+ and Fgf21−/− mice were pretreated with or without CORM2 (20 mg/kg) or RuCl2 as control for ruthenium, for 6 h, followed by Tm (1 mg/kg) challenge. After 24 h, the mice were euthanized, and liver tissues were extracted and analyzed by H&E staining. B–D) Liver triglyceride (B), serum ALT (C), and AST (D) levels were measured after stimulation with Tm. E) Serum FGF21 levels were detected by ELISA. F, G) The mRNA expression of FGF21 in liver tissues was measured by RT-PCR (F) and qRT-PCR (G). Data are presented as means ± sem (n = 3). NS, not significant. ***P < 0.001.
Figure 5.
Figure 5.
CO regulates lipolysis through the induction of FGF21 expression. A) H&E staining of epididymal WAT from Fgf21+/+ and Fgf21−/− mice that had been fed a NCD or HFD for 16 wk with CO inhalation. B) OCR was measured in AML12 cells transfected with scRNA and siRNA against Fgf21 in the presence of CORM2 (20 μM) and RuCl2 as control for ruthenium to detect energy expenditure and mitochondrial function. CE) The weight of eWAT (C), iWAT (D), and brown fat (E) was investigated after 16 wk of NCD and HFD feeding with CO inhalation. F) The lipolysis-related genes (ATGL, HSL, Plin1, and PPARγ) from Fgf21+/+ and Fgf21−/− eWAT were measured by qRT-PCR. Data are presented as means ± sem (n = 6). NS, not significant. *P < 0.05; **P < 0.01, ***P < 0.001.
Figure 6.
Figure 6.
CO-mediated induction of thermogenic genes is regulated by the FGF21 expression. AE) The mRNA expression of genes [UCP1 (A), PGC1α (B), PRDM16 (C), Cidea (D), and Cited (E)] associated with thermogenesis from Fgf21+/+ and Fgf21−/− iWAT, were detected by qRT-PCR. Data are presented as means ± sem (n = 6). NS, not significant. *P < 0.05, **P < 0.01, ***P < 0.001. F) In mice with diet-induced obesity, CO increases FGF21 expression mediated by the PERK-ATF4 signaling pathway, which induces lipolysis and thermogenesis of WAT to regulate the metabolic homeostasis.

Similar articles

See all similar articles

Cited by 6 PubMed Central articles

See all "Cited by" articles

References

    1. Panchal S. K., , Brown L. (2011) Rodent models for metabolic syndrome research. J. Biomed. Biotechnol. 2011, 351982. - PMC - PubMed
    1. Tamashiro K. L., , Sakai R. R., , Shively C. A., , Karatsoreos I. N., , Reagan L. P. (2011) Chronic stress, metabolism, and metabolic syndrome. Stress 14, 468–474 - PubMed
    1. Lindsay R. S., , Howard B. V. (2004) Cardiovascular risk associated with the metabolic syndrome. Curr. Diab. Rep. 4, 63–68 - PubMed
    1. Eckel R. H., , Grundy S. M., , Zimmet P. Z. (2005) The metabolic syndrome. Lancet 365, 1415–1428 - PubMed
    1. Kim C. S., , Kwon Y., , Choe S. Y., , Hong S. M., , Yoo H., , Goto T., , Kawada T., , Choi H. S., , Joe Y., , Chung H. T., , Yu R. (2015) Quercetin reduces obesity-induced hepatosteatosis by enhancing mitochondrial oxidative metabolism via heme oxygenase-1. Nutr. Metab. (Lond.) 12, 33. - PMC - PubMed

Publication types

MeSH terms

LinkOut - more resources

Feedback