DIO Mice Research Articles

Insights into the modulatory effects of host-gut microbial xanthine co-metabolism on high-fat diet-fed mice.

Gut microbiota-mediated endobiotic and xenobiotic metabolism play crucial roles in disease progression, and drug therapy/toxicity. Our recent study suggested that gut microbiota-mediated xanthine metabolism is correlated with resistance to high-fat diet (HFD)-induced obesity. Here, we explored the role of host-gut microbial xanthine co-metabolism in the prevention and treatment of HFD-induced obesity by orally administration of Bifidobacterium longum, xanthine, and a xanthine oxidase inhibitor (topiroxostat). The findings indicate that xanthine exhibits a significantly protective effect against HFD-induced obesity. While B. longum, xanthine, and topiroxostat did not alleviate the dysbiosis of the weight and glucose metabolism of HFD-induced obesity (DIO) and obesity resistance (DIR) mice. 16S rRNA sequencing analyses revealed that treatments with B. longum significantly altered gut microbiota composition in HFD-fed and DIO mice. Microbial interaction network analysis revealed several Bacteroidetes species, such as Amulumruptor caecigallinarius and Muribaculum intestinale, as keystone taxa that were notably enriched by B. longum. Untargeted metabolomics analysis implied that xanthine might serve as a crucial molecule in regulating body weight, exerting a preventive effect on HFD-induced obesity. This study offers new perspectives on the influence of host-gut microbial xanthine co-metabolism on HFD-fed mice and emphasizes the promising role of xanthine in promoting weight loss.

Lead-in calorie restriction enhances the weight-lowering efficacy of incretin hormone-based pharmacotherapies in mice

ObjectivesThe potential benefits of combining lifestyle changes with weight loss pharmacotherapies for obesity treatment are underexplored. Building on recent clinical observations, this study aimed to determine whether “lead-in” calorie restriction before administering clinically approved weight loss medications enhances the maximum achievable weight loss in preclinical models. MethodsDiet-induced obese mice (DIO) were exposed to 7 or 14 days of calorie restriction before initiating treatment with semaglutide (a glucagon-like peptide-1 receptor (GLP-1R) agonist), tirzepatide (a GLP-1R/glucose insulinotropic peptide receptor (GIPR) co-agonist), or setmelanotide (a melanocortin-4 receptor (MC4R) agonist). Follow-up assessments using indirect calorimetry determined the contributions of energy intake and expenditure linked to consecutive exposure to dieting followed by pharmacotherapy. ResultsCalorie restriction prior to treatment with semaglutide or tirzepatide enhanced the weight loss magnitude of both incretin-based therapies in DIO mice, reflected by a reduction in fat mass and linked to reduced energy intake and a less pronounced adaptive drop in energy expenditure. These benefits were not observed with the MC4R agonist, setmelanotide. ConclusionsOur findings provide compelling evidence that calorie restriction prior to incretin-based therapy enhances the achievable extent of weight loss, as reflected in a weight loss plateau at a lower level compared to that of treatment without prior calorie reduction. This work suggests that more intensive lifestyle interventions should be considered prior to pharmacological treatment, encouraging further exploration and discussion of the current standard of care.

Fetal growth restriction and placental defects in obese mice are associated with impaired decidualisation: the role of increased leptin signalling modulators SOCS3 and PTPN2

Decidualisation of the endometrium is a key event in early pregnancy, which enables embryo implantation. Importantly, the molecular processes impairing decidualisation in obese mothers are yet to be characterised. We hypothesise that impaired decidualisation in obese mice is mediated by the upregulation of leptin modulators, the suppressor of cytokine signalling 3 (SOCS3) and the protein tyrosine phosphatase non-receptor type 2 (PTPN2), together with the disruption of progesterone (P4)-signal transducer and activator of transcription (STAT3) signalling. After feeding mice with chow diet (CD) or high-fat diet (HFD) for 16 weeks, we confirmed the downregulation of P4 and oestradiol (E2) steroid receptors in decidua from embryonic day (E) 6.5 and decreased proliferation of stromal cells from HFD. In vitro decidualised mouse endometrial stromal cells (MESCs) and E6.5 deciduas from the HFD showed decreased expression of decidualisation markers, followed by the upregulation of SOCS3 and PTPN2 and decreased phosphorylation of STAT3. In vivo and in vitro leptin treatment of mice and MESCs mimicked the results observed in the obese model. The downregulation of Socs3 and Ptpn2 after siRNA transfection of MESCs from HFD mice restored the expression level of decidualisation markers. Finally, DIO mice placentas from E18.5 showed decreased labyrinth development and vascularisation and fetal growth restricted embryos. The present study revealed major defects in decidualisation in obese mice, characterised by altered uterine response to E2 and P4 steroid signalling. Importantly, altered hormonal response was associated with increased expression of leptin signalling modulators SOCS3 and PTPN2. Elevated levels of SOCS3 and PTPN2 were shown to molecularly affect decidualisation in obese mice, potentially disrupting the STAT3-PR regulatory molecular hub.

High-intensity interval training improves hypothalamic inflammation by suppressing HIF-1α signaling in microglia of male C57BL/6J mice.

Repeated bouts of high-intensity interval training (HIIT) induce an improvement in metabolism via plasticity of melanocortin circuits and attenuated hypothalamic inflammation. HIF-1α, which plays a vital role in hypothalamus-mediated regulation of peripheral metabolism, is enhanced in the hypothalamus by HIIT. This study aimed to investigate the effects of HIIT on hypothalamic HIF-1α expression and peripheral metabolism in obese mice and the underlying molecular mechanisms. By using a high-fat diet (HFD)-induced obesity mouse model, we determined the effect of HIIT on energy balance and the expression of the hypothalamic appetite-regulating neuropeptides, POMC and NPY. Moreover, hypothalamic HIF-1α signaling and its downstream glycolytic enzymes were explored after HIIT intervention. The state of microglia and microglial NF-κB signaling in the hypothalamus were also examined invivo. Invitro by using an adenovirus carrying shRNA-HIF1β, we explored the impact of HIF-1 signaling on glycolysis and NF-κB inflammatory signaling in BV2 cells. Food intake was suppressed and whole-body metabolism was improved in exercised DIO mice, accompanied by changes in the expression of POMC and NPY. Moreover, total and microglial HIF-1α signaling were obviously attenuated in the hypothalamus, consistent with the decreased levels of glycolytic enzymes. Both HFD-induced microglial activation and hypothalamic NF-κB signaling were significantly suppressed following HIIT invivo. In BV2 cells, after HIF-1 complex knockdown, glycolysis and NF-κB inflammatory signaling were significantly attenuated. The data indicate that HIIT improves peripheral metabolism probably via attenuated HFD-induced microglial activation and microglial NF-κB signaling in the hypothalamus, which could be mediated by suppressed microglial HIF-1α signaling.

Differential Impairment Mechanism of Sperm Production via Induction of miR-34c-Activated Apoptosis and Spermatogenesis Pathway in Diet-Induced Obesity and Resistant Mice and GC-1 Spg Cells.

Male reproductive dysfunction is a clinical disease, with a large number of cases being idiopathic. Reproductive disorders have been found in obese (diet-induced obesity and diet-induced obesity-resistant) mice, but the mechanism behind the male reproductive dysfunction between them may be different. The purpose of this study was to explore the possible role and mechanism of miR-34c on sperm production in high-fat-diet-induced obesity-resistant (DIO-R) mice and GC-1 spg cells, which may differ from those in high-fat-diet-induced obesity (DIO) mice. In vivo and in vitro experiments were performed. C57BL/6J mice were fed a high-fat diet for 10 weeks to establish the DIO and DIO-R mouse model. GC-1 spg cells were used to verify the mechanism of miR-34c on sperm production. During in vivo experiments, sperm production damage was found in both DIO and DIO-R male mice. Compared to the control mice, significantly decreased levels of testosterone, LH, activities of acrosome enzyme (ACE), HAse, and activating transcription factor 1 (ATF1) were found in both DIO and DIO-R male mice (p < 0.05). Compared with the control group, the ratio of B-cell lymphoma-2 (Bcl-2)/bcl-2-associated X protein (Bax) in the DIO group was significantly decreased, and the expression level of cleaved caspase-3 was significantly increased (p < 0.05). Compared with the control group, the Bcl-2 protein expression level in the testes of the DIO-R group significantly decreased (p < 0.05). However, the Bax expression level increased. Thus, the Bcl-2/Bax ratio significantly decreased (p < 0.01); however, the factor-related apoptosis (Fas), Fas ligand (FasLG), cleaved caspase-8, caspase-8, cleaved caspase-3, and caspase-3 protein expression levels significantly increased (p < 0.05). Compared with the DIO group, in DIO-R mice, the activities of ACE, ATF1, Bcl-2, and Bcl-2/Bax's spermatogenesis protein expression decreased, while the apoptosis-promoting protein expression significantly increased (p < 0.05). During the in vitro experiment, the late and early apoptotic ratio in the miR-34c over-expression group increased. MiR-34c over-expression enhanced the expression of apoptosis-related proteins Fas/FasLG and Bax/Bcl-2 while inhibiting the expression of ATF1 and the sperm-associated protein in GC-1 spg cells. DIO and DIO-R could harm sperm production. DIO-R could impair sperm production by inducing the miR-34c-activated apoptosis and spermatogenesis pathway, which may be different from that of DIO.

Design, synthesis, and biological evaluation of novel highly selective non-carboxylic acid FABP1 inhibitors

Histologic spectrum studies in patients revealed fatty acid binding proteins 1 (FABP1) as a potential new target for the treatment of metabolic associated fatty liver disease. However, there is no FABP1 inhibitor has been reported except the first-in-class FABP1 inhibitor bearing acid moiety reported by our laboratory. Herein, we firstly report the structure-activity relationship of novel non-carboxylic acid FABP1 inhibitors, which resulted in the identification of the potent and selective FABP1 inhibitor 30. The IC50 value of compound 30 for subtype FABP4 in the same family was greater than 80 μM. Moreover, compound 30 significantly alleviated the hepatic steatosis in DIO mice, which is equivalent to that of clinical drug obeticholic acid. This study might be provided a promising probe for the development of FABP1 inhibitors and thus can help to further elucidate the pharmacology of FABP1.

2059-LB: NA-931, a Novel Triple IGF-1/GLP-1/GIP Incretin Receptor Agonist Reduces Body Weight and Improves Metabolic Profile in DIO Mice

2059-LB: NA-931, a Novel Triple IGF-1/GLP-1/GIP Incretin Receptor Agonist Reduces Body Weight and Improves Metabolic Profile in DIO Mice

2057-LB: Amino Acids Plasma Levels Do Not Correlate with Lean Mass Loss in Weight-Matched DIO Mice Treated with Survodutide or Semaglutide

2057-LB: Amino Acids Plasma Levels Do Not Correlate with Lean Mass Loss in Weight-Matched DIO Mice Treated with Survodutide or Semaglutide

Improved leptin sensitivity and increased soluble leptin receptor concentrations may underlie the additive effects of combining PYY(3–36) and exendin-4 on body weight lowering in diet-induced obese mice

ObjectiveCo-treatment with long acting PYY and the GLP-1 receptor agonists has potential as an efficient obesity treatment. This study investigates whether the mechanisms behind additive reduction of food intake and weight loss depends on complementary effects in brain areas regulating food intake and if restoration of leptin sensitivity is involved. MethodsDiet-induced obese (DIO) mice were co-treated with PYY(3–36) and exendin-4 (Ex4, GLP-1R agonist) for 14 days using minipumps. Leptin responsiveness was evaluated by measuring food intake and body weight after leptin injection, and gene expression profile was investigated in various of brain regions and liver. ResultsWe show that weight loss associated with co-treatment of PYY(3–36) and Ex4 and Ex4 mono-treatment in DIO mice increased expression of several genes in area postrema (AP) known to be involved in appetite regulation and Cart, Pdyn, Bdnf and Klb were synergistically upregulated by the co-treatment. The upregulations were independent of weight loss, as shown by inclusion of a weight matched control. Moreover, PYY(3–36) and Ex4 co-treatment resulted in synergistically upregulated plasma concentrations of soluble leptin receptor (SLR) and improved sensitivity to exogenous leptin demonstrated by food intake lowering. ConclusionThe study results suggest that synergistic upregulation of appetite-regulating genes in AP and improved leptin sensitivity are important mediators for the additive weight loss resulting from PYY and Ex4 co-treatment.

Abstract 3982: Evaluating the effects of obesity on immune responses in renal tumors

Abstract Understanding the effects of obesity on cancer progression and treatment is a critically important area of research. Obesity is reaching epidemic proportions in our country and is known to increase the risk for many cancers, including renal cell carcinoma, which is among the ten most common cancers in both men and women. Our lab has shown that obesity leads to worse outcomes in advanced renal cancer patients treated with immunotherapy as compared to lean patients, but the cause for this difference is unknown. To investigate this further, we utilized a murine model with diet-induced obese mice and lean mice that were challenged with orthotopic renal tumors. The tumors grew out over three weeks and were harvested for flow cytometry staining. We stained for markers associated with immune function to better characterize what might be causing patients with obesity to be less responsive to immunotherapy. Our preliminary findings show that DIO mice had a greater tumor burden than lean controls over time. We also found that there compositional differences in multiple subsets of T cells in DIO versus lean mice. In the future, we will expand our murine studies to evaluate the phenotype and function of both tumor cells and immune cells. Additionally, we will continue these studies in human samples to further examine associations between obesity and immunotherapy outcomes. Citation Format: Francesca Dempsey, Lyse Norian. Evaluating the effects of obesity on immune responses in renal tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3982.

Abstract 2189: Tirzepatide mitigates obesity-associated metabolic dysregulation and tumor progression in a mouse model of triple-negative breast cancer

Abstract Obesity is an established risk factor for breast cancer. Dietary and surgical weight loss interventions reduce breast cancer risk but have significant limitations to their widespread use as anticancer strategies. Incretin-based pharmaceuticals safely and effectively promote weight loss, but whether these drugs exert similar protective effects against cancer is unknown. Here we test whether weight loss induced by the glucagon-like peptide 1 (GLP-1)/glucose-dependent insulinotropic polypeptide (GIP) receptor agonist tirzepatide limits tumor growth in an orthotopic mouse model of triple-negative breast cancer. Ten-week-old female C57BL/6NCrl mice were randomized to either a 10 kcal% low-fat diet (control; n=14) or 60 kcal% high-fat diet to promote diet-induced obesity (DIO; n=43). After 18 weeks on diet, DIO mice were randomized by body weight to either i) remain on the high-fat diet (DIO; n=15); ii) lose weight with tirzepatide (TZP; n=13); or iii) lose weight with 30% daily calorie restriction relative to control mice (CR; n=15). All mice were subcutaneously injected with either TZP or vehicle every other day for 13 weeks with the following escalating dosing schedule: 3 nmol/kg TZP in week 1; 10 nmol/kg TZP in weeks 2-3; 20 nmol/kg TZP in weeks 4-7; 30 nmol/kg TZP in weeks 8-11; and 40 nmol/kg TZP in weeks 12-13. Fasting blood glucose and body composition was assessed after 9 weeks of weight loss, and 35,000 E0771 cells were orthotopically transplanted into the 4th mammary fat pad. Tumors growth was monitored for 4 weeks. TZP-treated mice lost on average &amp;gt;20% weight loss by week 4 and remained at or below 20% weight loss for the remainder of the study. Directly prior to E0771 tumor cell injections, TZP-treated mice had lost 23.6±8.9% body weight, versus 39.7±3.6% in CR mice. Relative to DIO mice, blood glucose control was restored in both weight loss groups (DIO: 149.5±18.5 mg/dl; TZP: 124.5±15.5 mg/dl; CR: 107.6±18.8 mg/dl) and &amp;gt;87.5% of the lost weight was attributed to fat mass, rather than lean mass, for TZP-treated and CR mice. Notably, tirzepatide suppressed tumor growth relative to DIO, but the CR group had a greater anticancer effect than TZP. Reduced tumor mass in both weight loss groups was accompanied by a significant reduction in circulating IGF-1, insulin, and leptin relative to DIO mice. These findings are timely and important because i) obesity is a highly prevalent metabolic disease that increases risk and progression of breast cancer and &amp;gt;13 other cancers; ii) incretin therapies, which show promise as highly effective weight loss drugs, are increasingly being prescribed; and iii) the tumor suppressive effects of tirzepatide described herein newly suggest incretin agonism as another propitious option for breaking the obesity-cancer link. Citation Format: Elaine M. Glenny, Alyssa N. Ho, Violet A. Kiesel, Fangxin Chen, Claire E. Gates, Evan M. Paules, Ruihan Xu, C. Alex Holt, Michael F. Coleman, Stephen D. Hursting. Tirzepatide mitigates obesity-associated metabolic dysregulation and tumor progression in a mouse model of triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2189.

Adipocyte-targeted celastrol delivery via biguanide-modified micelles improves treatment of obesity in DIO mice.

Obesity has emerged as a significant global health burden, exacerbated by serious side effects associated with existing anti-obesity medications. Celastrol (CLT) holds promise for weight loss but encounters challenges related to poor solubility and systemic toxicity. Here, we present chondroitin sulfate (CS)-derived micelles engineered for adipocyte-specific targeting, aiming to enhance the therapeutic potential of CLT while minimizing its systemic toxicity. To further enhance adipocyte affinity, we introduced a biguanide moiety into a micellar vehicle. CS is sequentially modified with hydrophilic metformin and hydrophobic 4-aminophenylboronic acid pinacol ester (PBE), resulting in the self-assembly of CLT-encapsulated micelles (MET-CS-PBE@CLT). This innovative design imparts amphiphilicity via the PBE moieties while ensuring the outward exposure of hydrophilic metformin moieties, facilitating active interactions with adipocytes. In vitro studies confirmed the enhanced uptake of MET-CS-PBE@CLT micelles by adipocytes, while in vivo studies demonstrated increased distribution within adipose tissues. In a diet-induced obese mouse model, MET-CS-PBE@CLT exhibited remarkable efficacy in weight loss without affecting food intake. This pioneering strategy offers a promising, low-risk, and highly effective solution to address the global obesity epidemic.

OXM-104, a potential candidate for the treatment of obesity, NASH and type 2 diabetes

ObjectiveDual glucagon-like peptide-1 (GLP-1) and glucagon receptor agonists are therapeutic agents with an interesting liver-specific mode of action suitable for metabolic complications. In this study, dual GLP-1 and glucagon receptor agonist OXM-104 is compared head-to-head with the once-daily dual GLP-1 and glucagon receptor agonist cotadutide and GLP-1 receptor agonist semaglutide to explore the metabolic efficacy of OXM-104. MethodsThe in vitro potencies of OXM-104, cotadutide and semaglutide were assessed using reporter assays. In addition, in vivo efficacy was investigated using mouse models of diet-induced obesity (DIO mice), diabetes (db/db mice) and diet-induced NASH mice (MS-NASH). ResultsOXM-104 was found to only activate the GLP-1 and glucagon with no cross-reactivity at the (GIP) receptor. Cotadutide was also found to activate the GLP-1 and glucagon receptors, whereas semaglutide only showed activity at the GLP-1 receptor. OXM-104, cotadutide, and semaglutide elicited marked reductions in body weight and improved glucose control. In contrast, hepatoprotective effects, i.e., reductions in steatosis and fibrosis, as well as liver fibrotic biomarkers, were more prominent with OXM-104 and cotadutide than those seen with semaglutide, demonstrated by an improved NAFLD activity score (NAS) by OXM-104 and cotadutide, underlining the importance of the glucagon receptor. ConclusionThese results show that dual GLP-1 and glucagon receptor agonism is superior to GLP-1 alone. OXM-104 was found to be a promising therapeutic candidate for the treatment of metabolic complications such as obesity, type 2 diabetes and NASH.

Testicular fat deposition attenuates reproductive performance via decreased follicle-stimulating hormone level and sperm meiosis and testosterone synthesis in mouse.

Testicular fat deposition has been reported to affect animal reproduction. However, the underlying mechanism remains poorly understood. The present study explored whether sperm meiosis and testosterone synthesis contribute to mouse testicular fat depositioninduced reproductive performance. High fat diet (HFD)-induced obesity CD1 mice (DIO) were used as a testicular fat deposition model. The serum hormone test was performed by agent kit. The quality of sperm was assessed using a Sperm Class Analyzer. Testicular tissue morphology was analyzed by histochemical methods. The expression of spermatocyte marker molecules was monitored by an immuno-fluorescence microscope during meiosis. Analysis of the synthesis of testosterone was performed by real-time polymerase chain reaction and reagent kit. It was found that there was a significant increase in body weight among DIO mice, however, the food intake showed no difference compared to control mice fed a normal diet (CTR). The number of offspring in DIO mice decreased, but there was no significant difference from the CTR group. The levels of follicle-stimulating hormone were lower in DIO mice and their luteinizing hormone levels were similar. The results showed a remarkable decrease in sperm density and motility among DIO mice. We also found that fat accumulation affected the meiosis process, mainly reflected in the cross-exchange of homologous chromosomes. In addition, overweight increased fat deposition in the testis and reduced the expression of testosterone synthesis-related enzymes, thereby affecting the synthesis and secretion of testosterone by testicular Leydig cells. Fat accumulation in the testes causes testicular cell dysfunction, which affects testosterone hormone synthesis and ultimately affects sperm formation.

Furan fatty acid extracted from Hevea brasiliensis latex increases muscle mass in mice

Skeletal muscle is essential for locomotion and plays a crucial role in energy homeostasis. It is regulated by nutrition, genetic factors, physical activity and hormones. Furan fatty acids (FuFAs) are minor fatty acids present in small quantities in food from plants and animals origin. Recently, we showed that a preventive nutritional supplementation with furan fatty acid in a DIO mouse model reduces metabolic disorders. The present study was designed to determine the influence of FuFA-F2 extracted from Hevea brasiliensis latex on skeletal muscle phenotype. In C2C12 myotubes we found that FuFA-F2 whatever the concentration used increased protein content. We revealed that in C2C12 myotubes FuFA-F2 (10 µM) increases protein synthesis as shown by the stimulation of mTOR phosphorylation. Next, to confirm in vivo our results C57Bl6 mice were supplemented by oral gavage with vehicle or FuFA-F2 (20 mg/kg) for 3 and a half weeks. We found that mice supplemented with FuFA-F2 had a greater lean mass than the control mice. In line with this observation, we revealed that FuFA-F2 increased muscle mass and promoted more oxidative muscle metabolism in mice as attested by cytochrome c oxidase activity. In conclusion, we demonstrated that FuFA-F2 stimulates muscle anabolism in mice in vitro and in vivo, mimicking in part physical activity. This study highlights that in vivo FuFA-F2 may have health benefits by increasing muscle mass and oxidative metabolism.

Targeting BCAA metabolism to potentiate metformin's therapeutic efficacy in the treatment of diabetes in mice.

An increasing body of evidence has shown that the catabolism of branched-chain amino acids (BCAAs; leucine, isoleucine and valine) is impaired in obese animals and humans, contributing to the development of insulin resistance and type 2 diabetes. Promoting BCAA catabolism benefits glycaemic control. It remains unclear whether BCAA catabolism plays a role in the therapeutic efficacy of currently used glucose-lowering drugs such as metformin. Mice were treated with vehicle or metformin (250 mg/kg per day) for more than 4 weeks to investigate the effects of metformin in vivo. In vitro, primary mouse hepatocytes and HepG2 cells were treated with 2 mmol/l metformin. The therapeutic efficacy of metformin in the treatment of type 2 diabetes was assessed in genetically obese (ob/ob) mice and high-fat-diet-induced obese (DIO) mice. Enhancing BCAA catabolism was achieved with a pharmacological agent, 3,6-dichlorobenzo[b]thiophene-2-carboxylic acid (BT2). The ob/ob mice were treated with a low-BCAA diet or intermittent protein restriction (IPR) to reduce BCAA nutritional intake. Metformin unexpectedly inhibited the catabolism of BCAAs in obese mice, resulting in an elevation of BCAA abundance. AMP-activated protein kinase (AMPK) mediated the impact of metformin on BCAA catabolism in hepatocytes. Importantly, enhancing BCAA catabolism via a pharmacological agent BT2 significantly potentiated the glucose-lowering effect of metformin while decreasing circulating BCAA levels in ob/ob and DIO mice. Similar outcomes were achieved by a nutritional approach of reducing BCAA intake. IPR also effectively reduced the circulating BCAA abundance and enhanced metformin's glucose-lowering effect in ob/ob mice. BT2 and IPR treatments reduced the expression of fructose-1,6-bisphosphatase 1, a rate-limiting enzyme in gluconeogenesis, in the kidney but not liver, indicating the involvement of renal gluconeogenesis. Metformin self-limits its therapeutic efficacy in the treatment of type 2 diabetes by triggering the suppression of BCAA catabolism. Enhancing BCAA catabolism pharmacologically or reducing BCAA intake nutritionally potentiates the glucose-lowering effect of metformin. These data highlight the nutritional impact of protein on metformin's therapeutic efficacy and provide new strategies targeting BCAA metabolism to improve metformin's effects on the clinical outcome in diabetes.

Engineering a potent and long-acting GLP-1/Y2 receptor dual agonist as a multi-agonist therapy for diabetes and obesity

Novel dual agonists for the glucagon-like peptide-1 (GLP-1) and Y2 receptor hold the potential for enhanced efficacy over GLP-1 receptor (GLP-1R) agonists in treating obesity and diabetes. In this study, we aimed to improve the stability and increase the drug development success rate of our previously identified GLP-1/Y2 receptor dual agonist, 6q. To achieve this, we first optimized the structure of the linker within 6q. Additionally, we explored various fatty acid albumin binders to further enhance the stability of 6q. These binders were mainly selected from approved or clinically developed GLP-1R agonists or GLP-1-based multi-agonists. Through this process, we were able to identify a lead peptide, xGLP/PYY-6, that exhibited comparable in vitro potency toward the GLP-1 and Y2 receptors as 6q but with significantly improved stability compared to 6q. In Kunming and DIO mice, xGLP/PYY-6 showed a comparable hypoglycemic effect to semaglutide, and a significantly better effect on inhibiting food intake than semaglutide. In a chronic study in DIO mice, xGLP/PYY-6 exhibited significant metabolic benefits, as reflected by regulation of lipid levels, improved glucose tolerance, weight loss, decreased hepatocellular vacuolation, and the reversal of steatosis effects caused by xGLP/PYY-6. These results indicate the potential of developing xGLP/PYY-6 as an antiobesity, lipid regulation, antisteatotic, and antidiabetic agent.

CRISPRa system activates myokines FGF21 and FNDC5: Promoting fat browning and improving diet‐induced obesity in mice

AbstractObesity causes metabolic disorders and is one of the important risk factors for diabetes. Myokines are widely involved in lipid metabolism through autocrine, paracrine and endocrine actions. FGF21 and Irisin, as representative myokines, can promote the browning of adipocytes and are potential targets for the treatment of obesity. This commentary discusses the research by Zhu et al. published in Clinical and Translational Medicine. In this study, the expression of FGF21 and FNDC5 is simultaneously activated by the CRISPRa system in vivo and in vitro. In vitro, the cell culture supernatant of C2C12 cells activated by the CRISPRa system significantly promoted the differentiation and browning of 3T3‐L1 cells; in vivo, injecting of AAV9‐dCas9‐VP64 virus could significantly reduce the body weight and fat mass of DIO mice due to an increase in browning of adipocytes.

Intragastric Safflower Yellow Alleviates HFD Induced Metabolic Dysfunction-Associated Fatty Liver Disease in Mice through Regulating Gut Microbiota and Liver Endoplasmic Reticulum Stress.

The gut microbiota was reported to play a significant role in the progression of the metabolic associated fatty liver disease (MAFLD). Our recent study suggested that gastrointestinal tract and liver were important targets mediating the anti-obesity effects of intragastric safflower yellow (SY). Therefore, our present study aims to investigate the effect of intragastric SY on MAFLD and possible mechanism. DIO mice were treated with 125 mg/kg/d SY for 12 weeks by gavage. We found intragastric SY significantly slowed weight gain of body, reduced the food intake and liver weight, improved hepatic steatosis, liver function and glucose metabolism in DIO mice. The comparison between OGTT and IPGTT illustrated OGTT produced a better improvement of glucose tolerance after SY treatment. We also found intragastric SY significantly increased the energy expenditure and locomotor activity of DIO mice. SY obviously decreased the expression of lipogenesis-associated and ERS-related genes in liver of DIO mice and PA-induced MAFLD hepatocyte model. Gut microbiota analysis demonstrated intragastric SY apparently changed the diversity and composition of gut microbiota of DIO mice. Further function prediction analysis indicated that gut microbiotas in SY-treated mice was positively related with energy metabolism, lipid metabolism and endocrine system. Intragastric SY has a significant therapeutic effect on MAFLD, which is mediated partly by modulating gut microbiota and improving liver ERS.

1676-P: A Novel GLP1R/GCGR Dual Agonist, DA-1726 Elicits Weight Loss Superior to Semaglutide in Diet-Induced Obese Rats

DA-1726 showed superior weight loss efficacy compared to Semaglutide (SEMA) in DIO mice. In this following study, a dose-response of DA-1726 was evaluated to determine the maximum efficacy in DIO rats that are known to have good translatability to human studies. The half-life of DA-1726 was longer in rats compared to mice, however the in vitro activity of DA-1726 against rat glucagon receptor was less potent than in the mouse, and plasma protein binding was approximately 10-fold higher in rats. Therefore, we set the effective dose for rats higher than for mice. DA-1726 was injected twice a week for about 4 weeks, a dose-dependent and significant weight loss effect was observed. The minimum effective dose in DIO rats was found to be 250 nmol/kg. Then, the maximum body weight loss effects of DA-1726 (500 and 1000 nmole/kg) and SEMA were compared in the DIO rat. In this study, DA-1726 showed an excellent weight loss effect than SEMA (32.6% for DA-1726 at a high dose vs. 24.0% for SEMA, p&amp;lt;0.05). The low-dose DA-1726 group showed a similar effect compared to SEMA even though they consumed more food. The high-dose DA-1726 group showed similar food intake as SEMA, but led to a higher weight loss effect. After repeated dosing, the high-dose DA-1726 significantly increased the expression of energy metabolism-related genes (Ucp1, Ppargc1a) in white adipose tissues (WAT), supporting increased energy expenditure. So then, in order to confirm whether this increased gene change was a direct effect leading to weight loss or an indirect effect caused by weight loss, we assessed the changes in gene expression after single dosing. DA-1726 (250 and 500 nmol/kg) induced small but significant weight loss 3 days after a single injection (-7.6% and -9.5% vs. control). However, the genes expression (Ucp1, Ppargc1a) in WAT was significantly increased only in the 500 nmol/kg-treated group suggesting a direct effect. Therefore, DA-1726 is expected to elicit excellent weight loss effects in humans with a new mechanism. Disclosure Y.Chae: None. T.Kim: None. I.Jung: None. H.Kim: None. M.Kim: Employee; Dong-A ST.