Author response: ACE2 pathway regulates thermogenesis and energy metabolism
Year: 2021
Type: peer-review
Abstract: Article Figures and data Abstract Editor's evaluation Introduction Results Discussion Materials and methods Data availability References Decision letter Author response Article and author information Metrics Abstract Identification of key regulators of energy homeostasis holds important therapeutic promise for metabolic disorders, such as obesity and diabetes. ACE2 cleaves angiotensin II (Ang II) to generate Ang-(1-7) which acts mainly through the Mas1 receptor. Here, we identify ACE2 pathway as a critical regulator in the maintenance of thermogenesis and energy expenditure. We found that ACE2 is highly expressed in brown adipose tissue (BAT) and that cold stimulation increases ACE2 and Ang-(1-7) levels in BAT and serum. Ace2 knockout mice (Ace2-/y) and Mas1 knockout mice (Mas1-/-) displayed impaired thermogenesis. Mice transplanted with brown adipose tissue from Mas1-/- display metabolic abnormalities consistent with those seen in the Ace2 and Mas1 knockout mice. In contrast, impaired thermogenesis of Leprdb/db obese diabetic mice and high-fat diet-induced obese mice were ameliorated by overexpression of Ace2 or continuous infusion of Ang-(1-7). Activation of ACE2 pathway was associated with improvement of metabolic parameters, including blood glucose, lipids, and energy expenditure in multiple animal models. Consistently, ACE2 pathway remarkably enhanced the browning of white adipose tissue. Mechanistically, we showed that ACE2 pathway activated Akt/FoxO1 and PKA pathway, leading to induction of UCP1 and activation of mitochondrial function. Our data propose that adaptive thermogenesis requires regulation of ACE2 pathway and highlight novel potential therapeutic targets for the treatment of metabolic disorders. Editor's evaluation Authors have found that ACE2 is highly expressed in brown adipose tissue (BAT), indicating ACE2 pathway as a critical regulator in the maintenance of thermogenesis and energy expenditure. Identifying new regulators of energy homeostasis authors have shed light on novel potential therapeutic targets for the treatment of metabolic disorders. https://doi.org/10.7554/eLife.72266.sa0 Decision letter Reviews on Sciety eLife's review process Introduction Energy imbalance and the associated metabolic syndromes have become a worldwide public health problem. Thus, identifying factors that can stimulate energy expenditure is instrumental to the development of therapeutics to reduce obesity associated disorders that affect over 10% of the world population (Dong et al., 2018). In the renin-angiotensin system (RAS), angiotensin-converting enzyme 2 (ACE2) cleaves angiotensin II (Ang II) to generate angiotensin-(1-7) (Ang-(1-7)). Ang-(1-7) is a heptapeptide hormone which acts mainly through G-protein-coupled receptor Mas1 (Santos et al., 2003). ACE2-Ang-(1-7)-Mas1 pathway works as a negative regulator of ACE-Ang II pathway in multiple disease states (Clarke and Turner, 2012). Our group focused on ACE2 originated from concerns of severe acute respiratory syndrome (SARS) in 2003. Ambient hyperglycemia occurred very early in SARS patients and was an independent predictor for death and morbidity in SARS patients (Yang et al., 2006). Interestingly, ACE2 is the functional receptor for SARS coronavirus (Lavoie and Sigmund, 2003). We reported that Ace2 knockout (Ace2-/y) mice exhibited progressive impairments in glucose tolerance indicating that ACE2 is a potential new target for the treatment of type 2 diabetes (Niu et al., 2008). In addition, we have demonstrated that ACE2 regulates mitochondrial function in pancreatic β-cells, inhibits hepatic insulin resistance, ameliorates hepatic steatosis, and improves glucose uptake in adipocytes (Cao et al., 2019; Cao et al., 2016; Cao et al., 2014; Liu et al., 2012a; Song et al., 2020; Yang et al., 2018). These findings support the hypothesis that the ACE2-Ang-(1-7)-Mas1 axis may have protective effects on metabolic syndrome. In this study, we reported the effects of ACE2 pathway on regulating thermogenesis and energy metabolism via modulating mitochondrial function. We found that Ace2-/y and Mas1 knockout (Mas1-/-) mice are cold intolerance. We provided compelling genetic, metabolic, physiological, histological, cellular, and molecular evidence to demonstrate that ACE2 pathway is a critical regulator in the maintenance of energy expenditure. This pathway regulates function of brown adipose tissue (BAT) and systemic energy metabolism. Mechanistically, ACE2 pathway activates both Akt/FoxO1 signaling and PKA signaling, leading to induction of uncoupling protein-1 (UCP1) and activation of mitochondrial function. Therefore, ACE2 pathway is a potential treatment target for metabolic disorders including diabetes, obesity, and even cardiovascular diseases. Results Acute cold exposure increases components of ACE2 pathway The major tissue of the body where energy is converted into the form of heat to maintain the body temperature is BAT. We found both mRNA level and protein level of Ace2 and Mas1 in BAT were obviously higher than the ones in subcutaneous white adipose tissue (scWAT) and epididymal white adipose tissue (eWAT) in mice (Figure 1A and B). Acute cold exposure caused a significant up-regulation of ACE2 protein expression in BAT (Figure 1C). Meanwhile, Ace2 mRNA levels in BAT, scWAT and eWAT, and Mas1 mRNA levels in BAT and eWAT were increased after exposed to 4 °C for 48 hr (Figure 1D and E). ACE2 and Ang-(1-7) were also marginally increased in serum upon cold challenge (Figure 1F and G). These results demonstrated a selective induction of ACE2 pathway in thermogenic adipose depots (BAT and scWAT) in response to cold environment. Figure 1 Download asset Open asset ACE2 pathway is activated by cold exposure. Eight-week-old male C57BL/6 J mice were housed at room temperature (RT) for 2 weeks before cold exposure at 4 °C for various time periods as indicated. (A) Levels of ACE2 and Mas1 protein from interscapular brown adipose tissue (BAT), subcutaneous and epididymal white adipose tissue (scWAT and eWAT) of C57BL/6 mice at room temperature (RT), as determined by Western blotting (n = 3/each group). (B) Levels of Ace2 and Mas1 mRNA from BAT, scWAT and eWAT of C57BL/6 mice at RT, as determined by qPCR (n = 3/each group). (C) Levels of ACE2 and Mas1 protein from interscapular BAT of C57BL/6 mice at RT or exposed to 4 °C for 6 hr, as determined by western blotting (n = 3/each group). (D, E) Levels of Ace2 and Mas1 mRNA from BAT, scWAT, eWAT and liver of C57BL/6 mice exposed to 4 °C for 24 hr, as determined by qPCR (n = 6/each group). (F, G) Serum levels of ACE2 (F) and Ang-(1-7) (G), as determined by ELISA (n = 4–6/each group). Data represent mean ± SEM. *p < 0.05, **p < 0.01 and ***p < 0.001 vs Control group by Student's t-test, or one-way ANOVA. Figure 1—source data 1 Numerical quantification data for Figure 1. https://cdn.elifesciences.org/articles/72266/elife-72266-fig1-data1-v4.xlsx Download elife-72266-fig1-data1-v4.xlsx ACE2 promotes thermogenesis and energy metabolism To explore the physiological roles of ACE2 in cold-induced adaptive thermogenesis, we used the HFD-induced Ace2-/y mice. ACE2 is essential for expression of neutral amino acid transporters in the gut (Hashimoto et al., 2012). This is consistent with our observation that Ace2-/y mice fed an HFD displayed significantly decreased weight compared to wild-type (WT) mice (Figure 2A). Serum Ang-(1-7) levels were decreased in the Ace2-/y mice (Figure 2B). Consistent with previous studies (Cao et al., 2014; Liu et al., 2012a; Niu et al., 2008; Shi et al., 2018; Zhang et al., 2016), Ace2-/y mice had an impaired glucose tolerance and abnormal lipid profiles (Figure 2—figure supplement 1A-C). Figure 2 with 1 supplement see all Download asset Open asset Ace2 deficiency impairs thermogenesis, BAT activity, and energy metabolism. Eight-week-old male Ace2-/y mice and their wild-type (WT) mice (controls) had a high-fat diet (HFD) for 8 weeks. (A) Body weight of Ace2-/y and WT mice fed a HFD for 8 weeks (n = 4–5/each group). (B) Serum levels of Ang-(1-7), as determined by ELISA (n = 4–6/each group). (C–E) Energy expenditure was evaluated by measurement of oxygen consumption (VO2) (C), carbon dioxide release (VCO2) (D) and energy expenditure (EE) (E) over a 24 hours period (n = 5/each group). (F) Core body temperature at 30 °C, 22°C and 4°C for 8 hr in Ace2-/y and WT mice (n = 5/each group). (G) Infrared thermal images at 22 °C in Ace2-/y and WT mice. (H) Representative tomography–computed tomography (PET-CT) image and standard uptake values (SUVs) (n = 4/each group). (I) Representative haematoxylin and eosin (H&E) staining and uncoupling protein-1 (UCP1) immunostaining from BAT sections of Ace2-/y and WT mice exposure at 4 °C (n = 5/each group). (J) Representative western blots showing the changes of key proteins of energy expenditure and thermogenesis in BAT of Ace2-/y and WT mice exposure at 4 °C (n = 3/each group). (K) Representative western blots showing the key protein changes in primary brown adipocytes from Ace2-/y and WT mice (n = 3/each group). (L) Representative immunofluorescent images of in vitro differentiated primary brown adipocytes of Ace2-/y and WT mice, primary brown adipocytes show staining for UCP1 (red), boron-dipyrromethene (BODIPY) (green; neutral lipid dye), and DAPI (blue; nuclei). (M) Continuous measurement of oxygen consumption rate (OCR) in primary brown adipocytes from Ace2-/y mice and WT littermates. Oxygen consumption was performed under basal conditions, following the addition of oligomycin (1 μM), the pharmacological uncoupler FCCP (1 μM) or the Complex III and I inhibitor antimycin A and rotenone (0.5 μM) (n = 4–5/each group). Data represent mean ± SEM. *p < 0.05, **p < 0.01 vs WT group by Student's t-test, or ANCOVA. Figure 2—source data 1 Numerical quantification data for Figure 2. https://cdn.elifesciences.org/articles/72266/elife-72266-fig2-data1-v4.xlsx Download elife-72266-fig2-data1-v4.xlsx A key factor for controlling energy homoeostasis is the balance between caloric intake and energy expenditure. Thus, we measured energy expenditure using a comprehensive laboratory animal monitoring system (CLAMS). We observed a decreased oxygen consumption (VO2), carbon dioxide release (VCO2) and energy expenditure (EE) in Ace2-/y mice (Figure 2C, D and E), without observable changes in food and/or water intake as well as physical activity, compared to the WT mice (Figure 2—figure supplement 1D-F). To further examine the differences in energy expenditure among these animals, we performed a cold tolerance test in order to gauge adaptive thermogenesis. Ace2-/y mice had lower thermogenesis than the WT mice in a cold environment (4 °C) (Figure 2—figure supplement 1G). To explore the source of thermogenesis, we analyzed the non-shivering thermogenesis (NST) of Ace2-/y mice in thermoneutral condition (30 °C), ambient temperature (22 °C) and acute cold (4 °C) for 8 hr. Ace2-/y mice had lower thermogenesis than the WT mice in either 22 °C or 4 °C (Figure 2F). This temperature difference was monitored by an infrared camera at 4 °C (Figure 2G). To investigate whether ACE2-induced thermogenesis was related to BAT function, we performed the Positron emission tomography–computed tomography (PET-CT) analysis and the results showed a higher PET-CT signal in BAT of the HFD-induced WT mice than Ace2-/y mice (Figure 2H). As expected, BAT in Ace2-/y mice displayed larger lipid droplets but reduced multilocular structures compared to the WT mice, and reduced UCP1 expression (Figure 2I). To evaluate the significance of cold-induced ACE2 for thermogenic function of BAT, the expression levels of a network of genes and proteins controlling energy expenditure and thermogenic programming were measured. Protein levels (UCP1, PGC1α, and ATP5A) (Figure 2J) and mRNA levels (Ucp1, Prmd16, and Pparg (Figure 2—figure supplement 1H)) in BAT from Ace2-/y were obviously decreased. To validate the above-mentioned change of thermogenesis of BAT was cell autonomous, primary brown adipocytes from Ace2-/y mice was fractionated and differentiated in vitro. Notably, the protein and mRNA expression of known BAT markers were robustly decreased in Ace2-deficient primary brown adipocytes (Figure 2K, Figure 2—figure supplement 1I). Immunohistochemistry was applied to study the level of UCP1 in primary brown adipocytes differentiated from the BAT of the Ace2-/y mice. The result showed the UCP1 expression was reduced in the Ace2 deficiency primary brown adipocytes (Figure 2L). More importantly, the oxygen consumption rate (OCR) was significantly decreased in Ace2-deficient primary brown adipocytes (Figure 2M). As a complementary approach to the KO mouse models, we carried out gain-of-function studies using Ace2 over expression in obese diabetic Leprdb/db mice. One week following adenovirus-induced Ace2 over-expression (Ad-Ace2) by tail vein injection in the Leprdb/db mice, both ACE2 (Figure 3—figure supplement 1A) in BAT and circulating Ang-(1-7) (Figure 3A) were increased. Consistent with our previous study, the Ad-Ace2-treated mice exhibited an improved metabolic profile as indicated by the significant alleviation of glucose intolerance (Figure 3—figure supplement 1B). Notably, although no observable change on the body weight was observed in the two groups (Figure 3B), serum triglyceride levels decreased in the Ad-Ace2-treated mice (Figure 3—figure supplement 1C), as well as a minor change in serum cholesterol levels (Figure 3—figure supplement 1D). Figure 3 with 1 supplement see all Download asset Open asset ACE2 enhances thermogenesis, BAT activity, and energy metabolism in Leprdb/db obese mice. Ace2 over-expression adenovirus (Ad-Ace2) and Ad-GFP (control) were introduced into the Leprdb/db obese mice by tail vein injection. The ad-Ace2 and Ad-GFP treated Leprdb/db mice were used at the 6th day post-virus injection. (A) Serum levels of Ang-(1-7), as determined by ELISA (n = 6–7/each group). (B) Body weight of ad-Ace2 and Ad-GFP treated Leprdb/db mice at the 6th day post-virus injection (n = 4–6/each group). (C–E) Energy expenditure was evaluated by measurement of oxygen consumption (VO2) (C), carbon dioxide release (VCO2) (D) and energy expenditure (EE) (E) over a 24-hr period (n = 4–6/each group). (F) Core body temperature at 30 °C, 22°C and 4°C for 8 hr (n = 5/each group). (G) Infrared thermal images at 22 °C in Leprdb/db+ Ace2 and Leprdb/db+ GFP mice (n = 4/each group). (H) Representative tomography–computed tomography (PET-CT) image and standard uptake values (SUVs) (n = 4/each group). (I) Representative H&E staining and UCP1 immunostaining from BAT sections of Leprdb/db+ Ace2 and Leprdb/db+ GFP mice exposure at 4 °C (n = 5/each group). (J) Representative western blots showing the changes of key proteins of energy expenditure and thermogenesis in BAT of Leprdb/db+ Ace2 and Leprdb/db+ GFP mice exposure at 4 °C (n = 3/each group). (K) Relative mRNA levels of mitochondrial related genes, fatty acid oxidation related genes and transcription factors in BAT of Leprdb/db+ Ace2 and Leprdb/db+ GFP mice exposure at 4 °C (n = 5–6/each group). Data represent mean ± SEM. *p < 0.05, **p < 0.01 vs Ad-GFP group by Student's t-test, or ANCOVA. Figure 3—source data 1 Numerical quantification data for Figure 3. https://cdn.elifesciences.org/articles/72266/elife-72266-fig3-data1-v4.xlsx Download elife-72266-fig3-data1-v4.xlsx Notably, the Ad-Ace2-treated Leprdb/db mice had increased energy expenditure (VO2, VCO2 and EE) (Figure 3C–E). There was no obvious change in food and/or water intake as well as physical activity (Figure 3—figure supplement 1E-G). We measured rectal temperature and infrared thermal imaging in the Leprdb/db mice that BAT activity was defective as same as the ones in previous observations (Trayhurn and Wusteman, 1990; Zhang et al., 2014). The results showed that the thermogenesis of the Leprdb/db mice was severely impaired (Figure 3—figure supplement 1H, I). As expected, the Ad-Ace2 treated Leprdb/db mice and HFD-induced obese mice exhibited better thermogenesis than the control mice in ambient temperature (22 °C) and acute cold (4 °C) conditions (Figure 3F and G, Figure 3—figure supplement 1J,K). Accordingly, PET-CT result showed that BAT was activated in the Ad-Ace2-treated Leprdb/db mice (Figure 3H). Moreover, BAT in the Ad-Ace2-treated Leprdb/db mice had smaller lipid droplets but increased multi-locular structures, and had increased UCP1 expression compared with the control group (Figure 3I). The protein levels of UCP1, ATP5A and UQCRC2 were significantly increased in the BAT from the Ad-Ace2 treated mice (Figure 3J). Consistently, the mRNA levels, including Ucp1, ATP synthase F1 subunit beta (Atp5b), Cox8b, Cox7a, fatty acid binding protein 4 (Fabp4), Cpt1a, Prdm16, Ppargc1a and Ppargc1b, were increased in the BAT from the Ad-Ace2-treated Leprdb/db mice (Figure 3K). Taken together, these results indicated that ACE2 effectively regulated the mitochondrial biogenesis and respiratory function in brown adipocytes. Ang-(1-7) promotes thermogenesis and energy metabolism To explore the direct physiological roles of Ang-(1-7) in cold-induced adaptive thermogenesis, Ang-(1-7) administration by subcutaneous implantation of micro-osmotic pumps in the Leprdb/db and the HFD-induced obese mice were employed. Serum Ang-(1-7) was increased in Ang-(1-7)-treated mice (Figure 4—figure supplement 1A). There are no significant differences in body weight between the Ang-(1-7)-treated Leprdb/db mice and the Leprdb/db control mice (Figure 4A); however, Ang-(1-7)-treated Leprdb/db mice has an improved glucose tolerance ability (Figure 4—figure supplement 1B) and better lipid profiles (Figure 4—figure supplement 1C, D). The Ang-(1-7)-treated HFD-induced obese mice displayed a lower body weight compared to the control (Figure 4B). Figure 4 with 1 supplement see all Download asset Open asset Ang-(1-7) promotes thermogenesis, BAT activity, and energy metabolism in the Leprdb/db and the HFD-induced obese mice. Ang-(1-7) administration by subcutaneous implanted micro-osmotic pumps in the Leprdb/db obese mice and the high-fat diet (HFD)-induced obese mice were used. The Leprdb/db mice were treated with Ang-(1-7) by subcutaneous infusion of Ang-(1-7) or saline using osmotic mini-pumps for 4 weeks. Six-week-old male C57BL/6 J mice were used to develop obesity by HFD diet for 8 weeks, and the mice treated with Ang-(1-7), A779 (an Ang-(1-7) antagonist), or saline by osmotic mini-pumps at the 4th weeks post-HFD. (A) Body weight of Leprdb/db+ Ang-(1-7) and Leprdb/db+ Vehicle mice at the 4th week post micro-osmotic pumps implantation (n = 5–6/each group). (B) Body weight of HFD + Ang-(1-7), HFD + A779 and HFD + Vehicle mice at the 4th week post micro-osmotic pumps implantation (n = 4–7/each group). (C–E) Energy expenditure was evaluated by measurement of oxygen consumption (VO2) (C), of carbon dioxide release (VCO2) (D) and of energy expenditure (EE) (E) over a 24 hr period in Leprdb/db+ Ang-(1-7) and Leprdb/db+ Vehicle mice (n = 4–6/each group). (F) Core body temperature at 30 °C, 22°C and 4°C for 8 hr in Leprdb/db+ Ang-(1-7) and Leprdb/db-Vehicle mice (n = 5/each group). (G) Infrared thermal images at 22 °C in Leprdb/db+ Ang-(1-7) and Leprdb/db+ Vehicle mice. (H) Core body temperature at 4 °C for the indicated lengths of time in HFD + Ang-(1-7), HFD + A779 and HFD + Vehicle mice (n = 4–5/each group). (I) Representative H&E staining and UCP1 immunostaining from BAT sections of Leprdb/db+ Ang-(1-7) and Leprdb/db+ Vehicle mice exposure at 4 °C (n = 5/each group). (J) Representative Positron emission tomography–computed tomography (PET-CT) image and SUVs of Leprdb/db+ Ang-(1-7) and Leprdb/db+ Vehicle mice (n = 4/each group). (K) Representative PET-CT image and SUVs of HFD + Ang-(1-7), HFD + A779 and HFD + Vehicle mice (n = 3/each group). (L) Representative western blots showing the changes of key proteins of energy expenditure and thermogenesis in BAT of Leprdb/db+ Ang-(1-7) and Leprdb/db+ Vehicle mice exposure at 4 °C (n = 3/each group). (M) Representative western blots showing the changes of key proteins of energy expenditure and thermogenesis in BAT of HFD + Ang-(1-7), HFD + A779 and HFD + Vehicle mice exposure at 4 °C (n = 3/each group). Data represent mean ± SEM. *p < 0.05, **p < 0.01 vs Vehicle group by Student's t-test, ANCOVA, or one-way ANOVA. Figure 4—source data 1 Numerical quantification data for Figure 4. https://cdn.elifesciences.org/articles/72266/elife-72266-fig4-data1-v4.xlsx Download elife-72266-fig4-data1-v4.xlsx Notably, the Ang-(1-7) treated Leprdb/db mice had increased energy expenditure (VO2, VCO2, and EE) (Figure 4C–E) without any changes in food and/or water intake as well as physical activity (Figure 4—figure supplement 1E-G). Moreover, the Ang-(1-7) treated Leprdb/db and the HFD-induced obese mice were better able to defend their body temperature during environmental cold (22 °C) and acute cold stress (4 °C) compared to the control (Figure 4F–H, Figure 4—figure supplement 1H). Meanwhile, the Ang-(1-7)-treated Leprdb/db mice had increased multi-locular structures but smaller lipid droplets, and increased UCP1 expression comparing to the control group (Figure 4I). Accordingly, the Ang-(1-7)-treated Leprdb/db and the HFD-induced obese mice showed more 18F-FDG uptake in the BAT than the control mice recorded by PET-CT (Figure 4J and K). The protein levels of UCP1 and PGC1α were significantly induced in the BAT from the Ang-(1-7) treated Leprdb/db and the HFD-induced obese mice (Figure 4L and M). The mRNA levels, including Ucp1, Ppargc1a, Cidea, Atp5b, Cox4, Cox8b, Cox7a, Mcad, and Fabp2, were increased in the BAT from the Ang-(1-7)-treated Leprdb/db mice (Figure 4—figure supplement 1I). To sum up, our results suggested that the enhanced thermogenesis effect in the Ad-Ace2 and Ang-(1-7) treated mice is caused by the increment of Ang-(1-7) levels, which demonstrates that Ang-(1-7) is crucial to the maintenance of thermogenesis. Ablation of Mas1 impairs thermogenesis in brown adipose tissue Since the Ang-(1-7), produced by ACE2, realized the function through the Mas1 receptor, these results above prompted us to hypothesize that the Mas1 receptor determines the effect of Ang-(1-7) in brown adipose tissue. Firstly, the HFD-induced Mas1-/-mice (low Ang-(1-7) action model) were used to assess the therapeutic effects (interventional effects) of Mas1 on energy metabolism. Although serum Ang-(1-7) levels were increased, the Mas1-/-mice had an impaired glucose tolerance, abnormal lipid profiles (Figure 5A, Figure 5—figure supplement 1A-C), and significantly increased body weight compared to the WT mice (Figure 5B). Meanwhile, the Mas1-/- mice exhibited decreased oxygen consumption (VO2) (Figure 5—figure supplement 1D) without any changes in food and/or water intake as well as physical activity (Figure 5—figure supplement 1E-G). Moreover, the Mas1-/- mice had lower thermogenesis than the WT mice in either 22 °C or 4 °C (Figure 5C, D and F). PET-CT analysis illustrated that the Mas1-/- mice has less 18F-FDG uptake in BAT than the WT mice (Figure 5E). Consistently, the Mas1-/- mice displayed larger lipid droplets and reduced multilocular structures, and had reduced UCP1 expression compared with the WT mice (Figure 5G). Nevertheless, deletion of Mas1 resulted in a striking repression of BAT thermogenic protein (UCP-1, UQCRC2, and SDHB) (Figure 5H) and genes (e.g. Ucp1, Prmd16, Ppargc1a, Ppargc1b, Atp5b, Cox7a, and Cpt1a) (Figure 5I). Figure with 1 supplement see all Download asset Open asset Ablation of Mas1 impairs thermogenesis, BAT activity, and metabolism. Eight-week-old male Mas1-/- mice and their WT (control) mice had a high-fat diet (HFD) for 8 weeks vs BAT of mice was from the interscapular the BAT from Mas1-/- mice, was transplanted into the interscapular of mice mice transplanted with BAT WT and epididymal white adipose tissue (eWAT) WT eWAT) were used as The mice were fed an HFD after the and for weeks vs WT BAT, WT (A) Serum levels of Ang-(1-7) as determined by ELISA in Mas1-/- and WT mice (n = group). (B) Body weight in Mas1-/- and WT mice fed an HFD for 8 weeks (n = 4–5/each group). (C) Core body temperature at 30 °C, 22°C and 4°C for 8 hr in Mas1-/- and WT mice (n = 5/each Infrared thermal images at 22 °C in Mas1-/- and WT mice. (E) Representative PET-CT image and SUVs of Mas1-/- and WT mice (n = 3/each group). (F) Core body temperature at 4 °C for the indicated lengths of time in Mas1-/- and WT mice (n = 4–5/each group). (G) Representative H&E staining and UCP1 immunostaining from BAT sections of Mas1-/- and WT mice exposure at 4 °C (n = 5/each group). (H) Representative western blots showing the changes of key proteins in BAT of Mas1-/- and WT mice exposure at 4 °C (n = 3/each group). (I) Relative mRNA levels of mitochondrial related genes, fatty acid oxidation related genes and transcription factors in BAT of in Mas1-/- and WT mice exposure at 4 °C (n = 5–6/each group). (J) glucose tolerance test and the under the in WT BAT and WT eWAT mice fed an HFD for 8 weeks after (n = 6–7/each group). (K) tolerance test and in WT BAT and WT eWAT mice fed an HFD for 8 weeks after (n = 5–6/each group). (L) Body weight time in WT BAT and WT eWAT mice fed an HFD over weeks after (n = group). Energy expenditure was evaluated by measurement of oxygen consumption (VO2) of carbon dioxide release (VCO2) and of energy expenditure (EE) over a 24 hr period in WT BAT and WT eWAT mice (n = 5/each group). Data represent mean ± SEM. *p < 0.05, **p < 0.01 vs group by Student's t-test, ANCOVA, or one-way ANOVA. Figure data 1 Numerical quantification data for Figure Download To investigate the of the Mas1 receptor in BAT, we Mas1 knockout mice BAT transplanted to the previous studies et al., et al., 2016), BAT of the mice was from the interscapular the BAT, which from and Mas1-/- mice, was transplanted into the interscapular of the mice + As mice transplanted with BAT + WT and epididymal white adipose tissue (eWAT) + WT eWAT) were used as control and negative the the mice were fed by HFD for weeks. Interestingly, compared with the WT + WT BAT control mice, the WT + mice showed impaired HFD-induced insulin There is no significant difference between the WT + mice and the WT + WT eWAT mice in glucose tolerance test and the insulin tolerance test (Figure and K). Notably, also induced HFD-induced weight in the WT + mice compared with the WT + WT BAT control mice (Figure More importantly, compared to the WT + WT BAT control mice, the WT + mice had decreased oxygen consumption (VO2), carbon dioxide release and energy expenditure (EE) (Figure with food and/or water intake as well as physical activity (Figure 5—figure supplement Taken together, these results demonstrate that the Mas1 receptor can thermogenic in brown adipose ACE2 pathway white browning and thermogenesis we the of on the process of browning of a in subcutaneous white adipose tissue of scWAT from the Ad-Ace2-treated Leprdb/db obese mice showed a a adipocytes with multiple lipid compared with the control (Figure Meanwhile, markers of brown such as Ucp1, were significantly increased in scWAT of the Ad-Ace2-treated Leprdb/db mice. A induction of transcription including Prmd16, Ppargc1a and Ppargc1b, occurred in the scWAT of the Ad-Ace2-treated group (Figure As expected, the Ang-(1-7) treated Leprdb/db mice had a browning effect as the Ad-Ace2-treated Leprdb/db mice in and thermogenic expression levels were observed in the scWAT after Ang-(1-7) treatment (Figure and D). Figure 6 Download asset Open asset ACE2 pathway induced white adipose tissue browning in the Leprdb/db obese mice. (A) Representative H&E staining from subcutaneous white adipose tissue (scWAT) sections of Leprdb/db+ Ace2 and Leprdb/db+ GFP mice exposure at 4 °C (n = 6–7/each group). (B) Relative mRNA levels of mitochondrial related genes, fatty acid oxidation related genes and transcription factors in scWAT of Leprdb/db+ A
Source: eLife
Authors: Xi Cao, Ting-Ting Shi, Chuan-Hai Zhang, Wan-Zhu Jin, Li-Ni Song, Yi-Chen Zhang, Jing-Yi Liu, Fang-Yuan Yang, Charles N Rotimi, Aimin Xu, Jin-Kui Yang
Language: English
Subfield: Physiology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,500
OpenAlex ID: W4206658084