The protease SENP2 controls hepatic gluconeogenesis by regulating the SUMOylation of the fuel sensor AMPKα

Genetic subtyping of obesity reveals biological insights into the uncoupling of adiposity from its cardiometabolic comorbidities

Obesity is a highly heterogeneous disease that cannot be captured by one single adiposity trait. Here, we performed a multi-trait analysis to study obesity in the context of its common cardiometabolic comorbidities, acknowledging that not all individuals with obesity suffer from cardiometabolic comorbidities and that not all those with normal weight clinically present without them. We leveraged individual-level genotype-phenotype data of 452,768 individuals from the UK Biobank and designed uncoupling phenotypes that are continuous and range from high adiposity with a healthy cardiometabolic profile to low adiposity with an unhealthy cardiometabolic profile. Genome-wide association analyses of these uncoupling phenotypes identified 266 independent variants across 205 genomic loci where the adiposity-increasing allele is also associated with a lower cardiometabolic risk. Consistent with the individual variant effects, a genetic score (GRSuncoupling) that aggregates the uncoupling effects of the 266 variants was associated with lower risk of cardiometabolic disorders, including dyslipidemias (OR=0.92, P=1.4×10-89), type 2 diabetes (OR=0.94, P=6×10-21), and ischemic heart disease (OR=0.96, P=7×10-11), despite a higher risk of obesity (OR=1.16, P=4×10-108), which is in sharp contrast to the association profile observed for the adiposity score (GRSBFP). Nevertheless, a higher GRSuncoupling score was also associated with a higher risk of other, mostly weight-bearing disorders, to the same extent as the GRSBFP. The 266 variants clustered into eight subsets, each representing a genetic subtype of obesity with a distinct cardiometabolic risk profile, characterized by specific underlying pathways. Association of GRSuncoupling and GRSBFP with levels of 2,920 proteins in plasma found 208 proteins to be associated with both scores. The majority (85%) of these overlapping GRS-protein associations were directionally consistent, suggesting adiposity-driven effects. In contrast, levels of 32 (15%) proteins (e.g. IGFBP1, IGFBP2, LDLR, SHBG, MSTN) had opposite directional effects between GRSBFP and GRSuncoupling, suggesting that cardiometabolic health, and not adiposity, associated with their levels. Follow-up analyses provide further support for adipose tissue expandability, insulin secretion and beta-cell function, beiging of white adipose tissue, inflammation and fibrosis. They also highlight mechanisms not previously implicated in uncoupling, such as hepatic lipid accumulation, hepatic control of glucose homeostasis, and skeletal muscle growth and function. Taken together, our findings contribute new insights into the mechanisms that uncouple adiposity from its cardiometabolic comorbidities and illuminate some of the heterogeneity of obesity, which is critical for advancing precision medicine.

Increased hepatic gluconeogenesis and type 2 diabetes mellitus

Abnormally increased hepatic gluconeogenesis is a significant contributor to hyperglycemia in the fasting state in patients with type 2 diabetes mellitus (T2DM) due to insulin resistance. Metformin, the most prescribed drug for the treatment of T2DM, is believed to exert its effect mainly by reducing hepatic gluconeogenesis. Here, we discuss how increased hepatic gluconeogenesis contributes to T2DM and we review newly revealed mechanisms underlying the attenuation of gluconeogenesis by metformin. In addition, we analyze the recent findings on new determinants involved in the regulation of gluconeogenesis, which might ultimately lead to the identification of novel and targeted treatment strategies for T2DM.

Exploring potential targets for natural product therapy of DN: the role of SUMOylation

Diabetic nephropathy (DN) is a common and serious micro-vascular complication of diabetes and a leading cause of end-stage renal disease globally. This disease primarily affects middle-aged and elderly individuals, especially those with a diabetes history of over 10 years and poor long-term blood glucose control. Small ubiquitin-related modifiers (SUMOs) are a group of reversible post-translational modifications of proteins that are widely expressed in eukaryotes. SUMO proteins intervene in the progression of DN by modulating various signaling cascades, such as Nrf2-mediated oxidative stress, NF-κB, TGF-β, and MAPK pathways. Recent advancements indicate that natural products regulating SUMOylation hold promise as targets for intervening in DN. In a previous article published in 2022, we reviewed the mechanisms by which SUMOylation intervenes in renal fibrosis and presented a summary of some natural products with therapeutic potential. Therefore, this paper will focus on DN. The aim of this review is to elucidate the mechanism of action of SUMOylation in DN and related natural products with therapeutic potential, thereby summarising the targets and candidate natural products for the treatment of DN through the modulation of SUMOylation, such as ginkgolic acid, ginkgolide B, resveratrol, astragaloside IV, etc., and highlighting that natural product-mediated modulation of SUMOylation is a potential therapeutic strategy for the treatment of DN as a potential therapeutic strategy.

Artemisinins ameliorate polycystic ovarian syndrome by mediating LONP1-CYP11A1 interaction

Polycystic ovary syndrome (PCOS), a prevalent reproductive disorder in women of reproductive age, features androgen excess, ovulatory dysfunction, and polycystic ovaries. Despite its high prevalence, specific pharmacologic intervention for PCOS is challenging. In this study, we identified artemisinins as anti-PCOS agents. Our finding demonstrated the efficacy of artemisinin derivatives in alleviating PCOS symptoms in both rodent models and human patients, curbing hyperandrogenemia through suppression of ovarian androgen synthesis. Artemisinins promoted cytochrome P450 family 11 subfamily A member 1 (CYP11A1) protein degradation to block androgen overproduction. Mechanistically, artemisinins directly targeted lon peptidase 1 (LONP1), enhanced LONP1-CYP11A1 interaction, and facilitated LONP1-catalyzed CYP11A1 degradation. Overexpression of LONP1 replicated the androgen-lowering effect of artemisinins. Our data suggest that artemisinin application is a promising approach for treating PCOS and highlight the crucial role of the LONP1-CYP11A1 interaction in controlling hyperandrogenism and PCOS occurrence.

NR2F6 is essential for brown adipocyte differentiation and systemic metabolic homeostasis

OBJECTIVE

Brown adipose tissue (BAT) development and function are essential for maintaining energy balance. However, the key factors that specifically regulate brown adipogenesis require further identification. Here, we demonstrated that the nuclear receptor subfamily 2 group F member 6 (NR2F6) played a pivotal role in brown adipogenesis and energy homeostasis.

METHODS

We examined the differentiation of immortalized brown adipocytes and primary brown adipocytes when NR2F6 were deleted, and explored the mechanism through which NR2F6 regulated adipogenesis using ChIP-qPCR in vitro. Male wild type (WT) and Pdgfra-Cre-mediated deletion of Nr2f6 in preadipocytes (NR2F6-PKO) mice were fed with high fat diet (HFD) for 12 weeks, and adiposity, glucose intolerance, insulin resistance and inflammation were assessed.

RESULTS

NR2F6 exhibited abundant expression in BAT, while its expression was minimal in white adipose tissue (WAT). Within BAT, NR2F6 was highly expressed in preadipocytes, experienced a transient increase in the early stage of brown adipocyte differentiation, and significantly decreased in the mature adipocytes. Depletion of NR2F6 in preadipocytes inhibited brown adipogenesis, caused hypertrophy of brown adipocytes, and impaired thermogenic function of BAT, but without affecting WAT development. NR2F6 transcriptionally regulated PPARγ expression to promote adipogenic process in brown adipocytes. Loss of NR2F6 in preadipocytes led to increased susceptibility to diet-induced metabolic disorders.

CONCLUSIONS

Our findings unveiled NR2F6 as a novel key regulator of brown adipogenesis, potentially opening up new avenues for maintaining metabolic homeostasis by targeting NR2F6.

Sox6 impairs the adipogenic commitment of mesenchymal stem cells by targeting lysyl oxidase and preadipocyte factor 1

The commitment of mesenchymal stem cells (MSCs) to preadipocytes and the termination of differentiation to adipocytes are critical for maintaining systemic energy homeostasis. However, our knowledge of the molecular mechanisms governing the commitment of MSCs to preadipocytes and the subsequent termination of their differentiation into adipocytes remain limited. Additionally, the role of Sox6 sex-determining region Y (SRY)-box6 (Sox6), a transcription factor that regulates gene transcription, is reportedly involved in various cellular processes, including adipogenesis; however, its function in regulating preadipocyte development and the factors involved in the termination of adipogenic differentiation remain unexplored. Therefore, we investigated the role of Sox6 in regulating the differentiation of adipocytes by monitoring the effects of its overexpression in C3H10T1/2 cells (in vitro) and C57BL/6J mouse (in vivo) models of adipogenesis. We observed lower Sox6 expression in the adipose tissue of obese mice than that in control mice. Sox6 overexpression inhibited the differentiation of MSC by directly binding to the lysyl oxidase (Lox) and preadipocyte factor 1 (Pref1) promoters, which was potentiated by histone deacetylase-1(HDAC1). Our findings suggest that Sox6 is a key regulator of MSC commitment to adipocytes; therefore, targeting the Sox6-mediated regulation of this process could offer potential therapeutic avenues for addressing obesity and related metabolic disorders.

Research progress of AMP-activated protein kinase and cardiac aging

The process of aging is marked by a gradual deterioration in the physiological functions and functional reserves of various tissues and organs, leading to an increased susceptibility to diseases and even death. Aging manifests in a tissue- and organ-specific manner, and is characterized by varying rates and direct and indirect interactions among different tissues and organs. Cardiovascular disease (CVD) is the leading cause of death globally, with older adults (aged >70 years) accounting for approximately two-thirds of CVD-related deaths. The prevalence of CVD increases exponentially with an individual's age. Aging is a critical independent risk factor for the development of CVD. AMP-activated protein kinase (AMPK) activation exerts cardioprotective effects in the heart and restores cellular metabolic functions by modulating gene expression and regulating protein levels through its interaction with multiple target proteins. Additionally, AMPK enhances mitochondrial function and cellular energy status by facilitating the utilization of energy substrates. This review focuses on the role of AMPK in the process of cardiac aging and maintaining normal metabolic levels and redox homeostasis in the heart, particularly in the presence of oxidative stress and the invasion of inflammatory factors.

The emerging roles of SUMOylation in the tumor microenvironment and therapeutic implications

Tumor initiation, progression, and response to therapies depend to a great extent on interactions between malignant cells and the tumor microenvironment (TME), which denotes the cancerous/non-cancerous cells, cytokines, chemokines, and various other factors around tumors. Cancer cells as well as stroma cells can not only obtain adaption to the TME but also sculpt their microenvironment through a series of signaling pathways. The post-translational modification (PTM) of eukaryotic cells by small ubiquitin-related modifier (SUMO) proteins is now recognized as a key flexible pathway. Proteins involved in tumorigenesis guiding several biological processes including chromatin organization, DNA repair, transcription, protein trafficking, and signal conduction rely on SUMOylation. The purpose of this review is to explore the role that SUMOylation plays in the TME formation and reprogramming, emphasize the importance of targeting SUMOylation to intervene in the TME and discuss the potential of SUMOylation inhibitors (SUMOi) in ameliorating tumor prognosis.

Hepatitis B virus X protein increases LASP1 SUMOylation to stabilize HER2 and facilitate hepatocarcinogenesis

The hepatitis B virus (HBV) X protein (HBX), a viral macromolecule, plays a vital role in the development of HBV-related hepatocellular carcinoma (HCC). Increased expression of HER2 is linked to HBV infection, and HBX is responsible for HER2 upregulation in HCC. Nevertheless, the underlying molecular mechanisms are not yet fully understood. In the study, we discovered that HBX promoted HER2 expression to facilitate the sensitization of the insulin signaling pathway and enhance the growth and migration of HCC cells. Mechanistically, the viral protein enhanced the stability of HER2 by preventing its ubiquitination-mediated proteasomal degradation through LASP1, which could bind to HER2. Furthermore, increased SUMOylation of LASP1 contributed to the upregulation of HER2 and the interaction of LASP1 with HER2. In addition, RANBP2 and RANGAP1 were found to interact with LASP1 and promote SUMOylation of LASP1 to upregulate HER2 expression in HBX-associated hepatoma cells. In summary, our work provides a novel insight into hepatocarcinogenesis mediated by HBX and estimates the detailed mechanisms related to the increase in HER2 regulated by the viral protein, which might help provide a theoretical basis for identifying novel targets for HBV-positive HCC treatment.

Treatment with EV-miRNAs Alleviates Obesity-Associated Metabolic Dysfunction in Mice

Most cells release extracellular vesicles (EVs) that can be detected circulating in blood. We and others have shown that the microRNA contents of these vesicles induce transcriptomic changes in acceptor cells, contributing to the adjustment of metabolic homeostasis in response to environmental demands. Here, we explore the potential for modulating obesity- and exercise-derived EV-microRNAs to treat the metabolic dysfunction associated with obesity in mice. Treatment with EV-miRNAs alleviated glucose intolerance and insulin resistance in obese mice to an extent similar to that of high-intensity interval training, although only exercise improved cardiorespiratory fitness and decreased body weight. Mechanistically, EV-miRNAs decreased fatty acid and cholesterol biosynthesis pathways in the liver, reducing hepatic steatosis and increasing insulin sensitivity, resulting in decreased glycemia and triglyceridemia. Our data suggest that manipulation of EV-miRNAs may be a viable strategy to alleviate metabolic dysfunction in obese and diabetic patients who are unable to exercise, although actual physical activity is needed to improve cardiorespiratory fitness.