Crosstalk between autophagy and insulin resistance: evidence from different tissues

SGLT-2i-A Useful Tool for Real-Life Metabolic and Body Weight Control in Type 2 Diabetes Mellitus Patients

Background and Objectives: Elevated blood sugar poses an increasingly significant challenge to healthcare systems worldwide. We aimed to assess the efficacy of the SGLT-2i class in achieving metabolic control in patients with T2DM within a real-world standard-of-care regimen. Material and Methods: A prospective analysis was conducted over 6 months including individuals receiving care in an outpatient department, with baseline assessments and follow-ups at 3 and 6 months. Results: A total of 280 patients were assessed, with a mean age of 63.69 ± 9.16, 53.9% of which were males, with a mean DM duration of 9.06 ± 5.64 years, and a DM duration varying from 6 months to 24 years. Discussion: Real-world evidence bridges the gap between guidelines and practice. It emphasizes the need to overcome clinical inertia in order to optimize patient outcomes and contributes to the body of evidence supporting the efficacy of fixed-dose SGLT-2i combinations in managing T2DM and associated comorbidities. Conclusions: We demonstrate the significant clinical and therapeutic impact of SGLT-2i in T2DM patients in a real-world setting. This class of medication not only positively influences glycemic and weight control but also reduces CV risk factors and visceral adiposity.

Deciphering significances of autophagy in the development and metabolism of adipose tissue

The mechanisms of adipose tissue activation and inactivation have been a hot topic of research in the last decade, from which countermeasures have been attempted to be found against obesity as well as other lipid metabolism-related diseases, such as type 2 diabetes mellitus and non-alcoholic fatty liver disease. Autophagy has been shown to be closely related to the regulation of adipocyte activity, which is involved in the whole process including white adipocyte differentiation/maturation and brown or beige adipocyte generation/activation. Dysregulation of autophagy in adipose tissue has been demonstrated to be associated with obesity. On this basis, we summarize the pathways and mechanisms of autophagy involved in the regulation of lipid metabolism and present a review of its pathophysiological roles in lipid metabolism-related diseases, in the hope of providing ideas for the treatment of these diseases.

Insulin Sensitivity and Muscle Loss in the Absence of Diabetes Mellitus: Findings from a Longitudinal Community-Based Cohort Study

Background/Objectives: Muscle loss is a serious complication in chronic disease patients, yet studies on long-term changes in muscle mass based on insulin sensitivity in the absence of diabetes mellitus are scarce. This community-based cohort study analyzed the longitudinal association between insulin sensitivity and muscle loss in middle-aged South Korean adults. Methods: This study included 6016 subjects (aged 40-65 years) from the Korean Genome and Epidemiology Study, conducted between 2001 and 2016. Fat-free mass, fat mass, body weight, and kidney function were assessed biennially. Subjects were categorized into four groups based on the composite (Matsuda) insulin sensitivity index (ISI) quartiles. The primary outcome was muscle loss, defined as a decline in fat-free mass of 10% or more from baseline. The secondary outcome was the occurrence of all-cause mortality. Results: During 69,480 person-years of follow-up, muscle loss occurred in 311 (5.2%) subjects. Multivariable Cox regression revealed a reverse-graded association between insulin sensitivity and muscle loss risk. Hazard ratios (95% confidence intervals) for the second, third, and highest ISI quartiles were 0.70 (0.51-0.94), 0.69 (0.50-0.95), and 0.65 (0.46-0.92), respectively, compared with the lowest quartile. Insulin sensitivity, however, was not significantly associated with all-cause mortality, though the mortality risk was higher in individuals with muscle loss. Conclusions: A reverse-graded relationship between insulin sensitivity and muscle loss risk was identified in middle-aged South Korean adults, with the lowest risk in the highest ISI quartile. These findings suggest that higher insulin sensitivity may reduce the risk of muscle loss.

Dawn-to-dusk intermittent fasting is associated with overexpression of autophagy genes: A prospective study on overweight and obese cohort

AIM AND BACKGROUND

A growing body of evidence supports the impact of intermittent fasting (IF) on longevity and healthy aging via the modulation of autophagy genes. The activation of the catabolic autophagic machinery (LAMP2, LC3B, ATG5, and ATG4D) has protective effects against degenerative aging and chronic diseases. This research examined the changes in the expression of the aforementioned genes upon the observance of dawn-to-dusk IF among metabolically healthy participants with overweight and obesity.

METHODS

Fifty-one (51) participants (36 males and 15 females, 38.84 ± 11.73 years) with overweight and obesity (BMI = 29.75 ± 5.04 kg/m2) were recruited and monitored before and at the end of the commencement of the four-week IF. Six healthy subjects with normal BMI (21.4 ± 2.20 kg/m2) were recruited only to standardize the reference for normal levels of gene expressions. At the two time points, anthropometric, biochemical, and dietary assessments were performed, and LAMP2, LC3B, ATG5, and ATG4D gene expressions were assessed using qRT-PCR on RNA extracted from whole blood samples.

RESULTS

At the end of IF, and compared to the pre-fasting levels, the relative gene expressions among participants with overweight/obesity were significantly increased for the three autophagy genes LAMP2, LC3B, and ATG5, with increments of about 4.2 folds, 1.9-fold, and 1.4-fold, respectively. In contrast, the increase in the ATG4D gene was not significant. Concomitantly, significant decreases were found in body weight, BMI, fat mass, body fat percent, hip and waist circumferences, LDL, IL-6, and TNF-a (P < 0.05), While HDL, IL-10, and CD163 significantly increased (P < 0.05). Binary logistic regression analysis for genetic expressions showed no significant association between high-energy intake, waist circumference, or obesity and the four gene expressions.

CONCLUSIONS

Four consecutive weeks of dawn-to-dusk IF of Ramadan is associated with the upregulation of autophagy gene expressions in participants with overweight/obesity, and this may explain, at least in part, its favorable short-term temporal metabolic and health-improving effects on early aging-related markers. Hence, IF presumably may entail a protective impact against early markers of aging and metabolic diseases in participants with overweight/obesity.

Exercise-driven cellular autophagy: A bridge to systematic wellness

BACKGROUND

Exercise enhances health by supporting homeostasis, bolstering defenses, and aiding disease recovery. It activates autophagy, a conserved cellular process essential for maintaining balance, while dysregulated autophagy contributes to disease progression. Despite extensive research on exercise and autophagy independently, their interplay remains insufficiently understood.

AIM OF REVIEW

This review explores the molecular mechanisms of exercise-induced autophagy in various tissues, focusing on key transduction pathways. It examines how different types of exercise trigger specific autophagic responses, supporting cellular balance and addressing systemic dysfunctions. The review also highlights the signaling pathways involved, their roles in protecting organ function, reducing disease risk, and promoting longevity, offering a clear understanding of the link between exercise and autophagy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Exercise-induced autophagy is governed by highly coordinated and dynamic pathways integrating direct and indirect mechanical forces and biochemical signals, linking physical activity to cellular and systemic health across multiple organ systems. Its activation is influenced by exercise modality, intensity, duration, and individual biological characteristics, including age, sex, and muscle fiber composition. Aerobic exercises primarily engage AMPK and mTOR pathways, supporting mitochondrial quality and cellular homeostasis. Anaerobic training activates PI3K/Akt signaling, modulating molecules like FOXO3a and Beclin1 to drive muscle autophagy and repair. In pathological contexts, exercise-induced autophagy enhances mitochondrial function, proteostasis, and tissue regeneration, benefiting conditions like sarcopenia, neurodegeneration, myocardial ischemia, metabolic disorders, and cancer. However, excessive exercise may lead to autophagic overactivation, leading to muscle atrophy or pathological cardiac remodeling. This underscores the critical need for balanced exercise regimens to maximize therapeutic efficacy while minimizing risks. Future research should prioritize identifying reliable biomarkers, optimizing exercise protocols, and integrating exercise with pharmacological strategies to enhance therapeutic outcomes.

Chemical characterization and DPP IV inhibitory capacity of purified adzuki bean β-vignin digest in comparison to soybean β-conglycinin and in vitro effect of β-vignin on diabetic-related outcomes

Adzuki bean (AB) is a legume with a low glycemic index and is traditionally used in Asian cultures to modulate type 2 diabetes (T2D). Our objectives were to characterize the functional peptides from purified AB β-vignin after simulated gastrointestinal digestion in comparison to soybean β-conglycinin, to evaluate their DPP IV inhibitory capacity, and to determine in vitro the effect of digested AB β-vignin on diabetic-related outcomes using HepG2 cells in healthy and insulin-resistant states. Five peptides (215-742 Da) from AB β-vignin and five peptides (215-447 Da) from β-conglycinin were identified to exhibit bioactivity as DPP IV inhibitors. Molecular docking demonstrated peptides could bind to DPP IV at the same binding site as a diabetic medication, linagliptin. Digested AB β-vignin significantly increased (p < 0.05) hepatic glucose uptake (> 290 %) via DPP IV inhibition (> 40 %) in healthy and insulin-resistant states. IRS-1, Akt-1, and Glut 2 increased after treating cells with digested AB β-vignin in healthy and insulin-resistant states.

Ergothioneine ameliorates metabolic dysfunction-Associated Steatotic Liver Disease (MASLD) by enhancing autophagy, inhibiting oxidative damage and inflammation

BACKGROUND

Metabolic dysfunction-associated steatosis liver disease (MASLD) is one of the most common metabolic liver diseases around the world, whose prevalence continues to increase. Currently, there are few medications to treat MASLD. Ergothioneine is a natural compound derived from mushrooms whose sulfhydryl groups confer unique antioxidant, anti-inflammatory and detoxifying effects. Currently, research on the therapeutic effects of ergothioneine in MASLD is unknown. Therefore, this study explored the effect and mechanism of EGT in MASLD.

METHODS

The ameliorative effects and mechanisms of ergothioneine on MASLD were evaluated using HFD mice and PA-treated AML12 cells. Mouse body weight, body fat, IPGTT, IPITT, immunohistochemistry, serum biochemical indices, and staining of liver sections were assayed to verify the protective role of ergothioneine in MASLD. RNA-seq was applied to explore the mechanism of action of ergothioneine. The role of ergothioneine in AML12 was confirmed by western blotting, qPCR, ELISA, Oil Red O staining, flow cytometry, and ROS assays. Subsequently, the 3-methyladenine (3-MA, an autophagy inhibitor) was subsequently used to confirm that ergothioneine alleviated MASLD by promoting autophagy.

RESULTS

Ergothioneine reduced body weight, body fat and blood lipids, and improved insulin resistance and lipid and glycogen deposition in MASLD mice. Furthermore, ergothioneine was found to increase autophagy levels and attenuate oxidative damage, inflammation, and apoptosis. In contrast, intervention with 3-MA abrogated these effects, suggesting that ergothioneine ameliorated effects by promoting autophagy.

CONCLUSION

Ergothioneine may be a drug with great therapeutic potential for MASLD. Furthermore, this protective effect was mediated through the activation of autophagy.

The role of low-carbohydrate, high-fat diet in modulating autophagy and endoplasmic reticulum stress in aortic endothelial dysfunction of metabolic syndrome animal model

Background

Endothelial dysfunction (ED) is induced by insulin resistance, mediated by endoplasmic reticulum (ER) stress and disturbed autophagy. This study investigates the protective role of a low-carbohydrate, high-fat (LCHF) diet on ED, ER stress, and autophagy dysregulation in an experimental animal model of metabolic syndrome.

Methods

Forty male Sprague-Dawley rats were divided into four groups: a Control group (standard diet) and three Dexamethasone (DEX) treated groups. Group II continued the standard diet, Group III received an LCHF diet, and Group IV received a high-carbohydrate, low-fat (HCLF) diet. At the end of the experiment, aortic tissue samples were obtained and used for histological, immunohistochemical (Endothelin and PCNA, biochemical MDA, TCA, NO, 8-OH-dG, and Nrf2/ARE protein) and molecular (Endothelin, eNOS, Nrf-2 α, p62, LC3, BECN-1, PINK1, CHOP, BNIP3, PCNA) analysis.

Results

Oxidative stress, autophagy markers, and ED markers are increased in the metabolic syndrome group. LCHF diet mitigates the adverse effects of DEX on endothelial dysfunction and oxidative stress, as evidenced by reduced BMI, HOMA-IR, and improved histological and molecular parameters.

Conclusion

Oxidative stress, autophagy dysregulation, and ER stress play crucial roles in the pathogenesis of insulin resistance-induced endothelial dysfunction. An LCHF diet offers protective benefits against insulin resistance and related comorbidities, including endothelial dysfunction.

The Role of Insulin Within the Socio-Psycho-Biological Framework in Type 2 Diabetes-A Perspective from Psychoneuroimmunology

The interplay between socio-psychological factors and biological systems is pivotal in defining human health and disease, particularly in chronic non-communicable diseases. Recent advancements in psychoneuroimmunology and mitochondrial psychobiology have emphasized the significance of psychological factors as critical determinants of disease onset, progression, recurrence, and severity. These insights align with evolutionary biology, psychology, and psychiatry, highlighting the inherent social nature of humans. This study proposes a theory that expands insulin's role beyond traditional metabolic functions, incorporating it into the Mitochondrial Information Processing System (MIPS) and exploring it from an evolutionary medicine perspective to explore its function in processing psychological and social factors into biological responses. This narrative review comprises data from preclinical animal studies, longitudinal cohort studies, cross-sectional studies, machine learning analyses, and randomized controlled trials, and investigates the role of insulin in health and disease. The result is a proposal for a theoretical framework of insulin as a social substance within the socio-psycho-biological framework, emphasizing its extensive roles in health and disease. Type 2 Diabetes Mellitus (T2DM) with musculoskeletal disorders and neurodegeneration exemplifies this narrative. We suggest further research towards a comprehensive treatment protocol meeting evolutionary expectations, where incorporating psychosocial interventions plays an essential role. By supporting the concept of 'insulin resilience' and suggesting the use of heart rate variability to assess insulin resilience, we aim to provide an integrative approach to managing insulin levels and monitoring the effectiveness of interventions. This integrative strategy addresses broader socio-psychological factors, ultimately improving health outcomes for individuals with T2DM and musculoskeletal complications and neurodegeneration while providing new insights into the interplay between socio-psychological factors and biological systems in chronic diseases.

Dysregulation of pancreatic β-cell autophagy and the risk of type 2 diabetes

Macroautophagy/autophagy is an essential degradation process that removes abnormal cellular components, maintains homeostasis within cells, and provides nutrition during starvation. Activated autophagy enhances cell survival during stressful conditions, although overactivation of autophagy triggers induction of autophagic cell death. Therefore, early-onset autophagy promotes cell survival whereas late-onset autophagy provokes programmed cell death, which can prevent disease progression. Moreover, autophagy regulates pancreatic β-cell functions by different mechanisms, although the precise role of autophagy in type 2 diabetes (T2D) is not completely understood. Consequently, this mini-review discusses the protective and harmful roles of autophagy in the pancreatic β cell and in the pathophysiology of T2D.

Effect of berberine combined with metformin on autophagy in polycystic ovary syndrome by regulating AMPK/AKT/mTOR pathway

The pathologic mechanism of polycystic ovary syndrome (PCOS) is related to increased autophagy of granulosa cells. Both berberine and metformin have been shown to improve PCOS, but whether the combination of berberine and metformin can better improve PCOS by inhibiting autophagy remains unclear. PCOS models were constructed by injecting dehydroepiandrosterone into rats, and berberine, metformin or berberine combined with metformin was administered to rats after modeling. Rats' body weight and ovarian weight were measured before and after modeling. Histopathological examination of ovarian tissue and estrous cycle analysis of rats were performed. Insulin resistance, hormone levels, oxidative stress, and lipid metabolism in PCOS rats were assessed. Expression of the AMPK/AKT/mTOR pathway and autophagy-related proteins was analyzed by Western blot assays. Granulosa cells were isolated from rat ovarian tissue and identified by immunofluorescence staining followed by transmission electron microscopy analysis. Berberine combined with metformin reduced the body weight and ovarian weight of PCOS rats, increased the number of primordial and primary follicles, decreased the number of secondary and atretic follicles, normalized the estrous cycle, and improved insulin resistance, androgen biosynthesis, oxidative stress and lipid metabolism disorders, and increased estrogen production. In addition, berberine combined with metformin reduced the number of autophagosomes in granulosa cells, which may be related to AMPK/AKT/mTOR pathway activation, decreased Beclin1 and LC3II/LC3I levels, and increased p62 expression. Berberine combined with metformin could inhibit autophagy by activating the AMPK/AKT/mTOR pathway in PCOS, indicating that berberine combined with metformin is a potential treatment strategy for PCOS.

SNP alleviates mitochondrial homeostasis dysregulation-mediated developmental toxicity in diabetic zebrafish larvae

The incidence of diabetes is increasing annually, and the disease is uncurable due to its complex pathogenesis. Therefore, understanding diabetes pathogenesis and developing new treatments are crucial. This study showed that the NO donor SNP (8 µM) significantly alleviated high glucose-induced developmental toxicity in zebrafish larvae. High glucose levels caused hyperglycemia, leading to oxidative stress and mitochondrial damage from excessive ROS accumulation. This promoted mitochondrial-dependent apoptosis and lipid peroxidation (LPO)-induced ferroptosis, along with immune inflammatory reactions that decreased mitochondrial function and altered intracellular grid morphology, causing imbalanced kinetics and autophagy. After SNP treatment, zebrafish larvae showed improved developmental toxicity and glucose utilization, reduced ROS accumulation, and increased antioxidant activity. The NO-sGC-cGMP signaling pathway, inhibited by high glucose, was significantly activated by SNP, improving mitochondrial homeostasis, increasing mitochondrial count, and enhancing mitochondrial function. It's worth noting that apoptosis, ferroptosis and immune inflammation were effectively alleviated. In summary, SNP improved high glucose-induced developmental toxicity by activating the NO-sGC-cGMP signaling pathway to reduce toxic effects such as apoptosis, ferroptosis and inflammation resulting from mitochondrial homeostasis imbalance.

Recent advances in the effect of adipose tissue inflammation on insulin resistance

Obesity is one of the major risk factors for diabetes. Excessive accumulation of fat leads to inflammation of adipose tissue, which can increase the risk of developing diabetes. Obesity-related chronic inflammation can result in anomalies in glucose-lipid metabolism and insulin resistance, and it is a major cause of β-cell dysfunction in diabetes mellitus. Thus, a long-term tissue inflammatory response is crucial for metabolic diseases, particularly type 2 diabetes. Chronic inflammation associated with obesity increases oxidative stress, secretes inflammatory factors, modifies endocrine variables, and interferes with insulin signalling pathways, all of which contribute to insulin resistance and glucose tolerance. Insulin resistance and diabetes are ultimately caused by chronic inflammation in the stomach, pancreas, liver, muscle, and fat tissues. In this article, we systematically summarize the latest research progress on the mechanisms of adipose tissue inflammation and insulin resistance, as well as the mechanisms of cross-talk between adipose tissue inflammation and insulin resistance, with a view to providing some meaningful therapeutic strategies for the treatment of insulin resistance by controlling adipose tissue inflammation.

The cellular adaptor GULP1 interacts with ATG14 to potentiate autophagy and APP processing

Autophagy is a highly conserved catabolic mechanism by which unnecessary or dysfunctional cellular components are removed. The dysregulation of autophagy has been implicated in various neurodegenerative diseases, including Alzheimer's disease (AD). Understanding the molecular mechanism(s)/molecules that influence autophagy may provide important insights into developing therapeutic strategies against AD and other neurodegenerative disorders. Engulfment adaptor phosphotyrosine-binding domain-containing protein 1 (GULP1) is an adaptor that interacts with amyloid precursor protein (APP) to promote amyloid-β peptide production via an unidentified mechanism. Emerging evidence suggests that GULP1 has a role in autophagy. Here, we show that GULP1 is involved in autophagy through an interaction with autophagy-related 14 (ATG14), which is a regulator of autophagosome formation. GULP1 potentiated the stimulatory effect of ATG14 on autophagy by modulating class III phosphatidylinositol 3-kinase complex 1 (PI3KC3-C1) activity. The effect of GULP1 is attenuated by a GULP1 mutation (GULP1m) that disrupts the GULP1-ATG14 interaction. Conversely, PI3KC3-C1 activity is enhanced in cells expressing APP but not in those expressing an APP mutant that does not bind GULP1, which suggests a role of GULP1-APP in regulating PI3KC3-C1 activity. Notably, GULP1 facilitates the targeting of ATG14 to the endoplasmic reticulum (ER). Moreover, the levels of both ATG14 and APP are elevated in the autophagic vacuoles (AVs) of cells expressing GULP1, but not in those expressing GULP1m. APP processing is markedly enhanced in cells co-expressing GULP1 and ATG14. Hence, GULP1 alters APP processing by promoting the entry of APP into AVs. In summary, we unveil a novel role of GULP1 in enhancing the targeting of ATG14 to the ER to stimulate autophagy and, consequently, APP processing.

Insulin resistance as the molecular link between diabetes and Alzheimer's disease

Diabetes mellitus (DM) and Alzheimer's disease (AD) are two major health concerns that have seen a rising prevalence worldwide. Recent studies have indicated a possible link between DM and an increased risk of developing AD. Insulin, while primarily known for its role in regulating blood sugar, also plays a vital role in protecting brain functions. Insulin resistance (IR), especially prevalent in type 2 diabetes, is believed to play a significant role in AD's development. When insulin signalling becomes dysfunctional, it can negatively affect various brain functions, making individuals more susceptible to AD's defining features, such as the buildup of beta-amyloid plaques and tau protein tangles. Emerging research suggests that addressing insulin-related issues might help reduce or even reverse the brain changes linked to AD. This review aims to explore the rela-tionship between DM and AD, with a focus on the role of IR. It also explores the molecular mechanisms by which IR might lead to brain changes and assesses current treatments that target IR. Understanding IR's role in the connection between DM and AD offers new possibilities for treatments and highlights the importance of continued research in this interdisciplinary field.

Autophagy and inflammation an intricate affair in the management of obesity and metabolic disorders: evidence for novel pharmacological strategies?

Unhealthy lifestyle habits including a sedentary life, the lack of physical activity, and wrong dietary habits are the major ones responsible for the constant increase of obesity and metabolic disorders prevalence worldwide; therefore, the scientific community pays significant attention to the pharmacotherapy of such diseases, beyond lifestyle interventions, the use of medical devices, and surgical approaches. The intricate interplay between autophagy and inflammation appears crucial to orchestrate fundamental aspects of cellular and organismal responses to challenging stimuli, including metabolic insults; hence, when these two processes are dysregulated (enhanced or suppressed) they produce pathologic effects. The present review summarizes the existing literature reporting the intricate affair between autophagy and inflammation in the context of metabolic disorders, including obesity, diabetes, and liver metabolic diseases (non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)). The evidence collected so far suggests that an alteration of autophagy might lead to maladaptive metabolic and inflammatory responses thus exacerbating the severity of the disease, and the most prominent conclusion underlies that autophagy might exert a protective function by contributing to balance inflammation. However, the complex nature of obesity and metabolic disorders might represent a limit of the studies; indeed, although many pharmacological treatments, producing positive metabolic effects, are also able to modulate autophagic flux and inflammation, it is not clear if the final beneficial effect might occur only by their mechanism of action, rather than because of additionally involved pathways. Finally, although future studies are needed, the observation that anti-obesity and antidiabetic drugs already on the market, including incretin mimetic agents, facilitate autophagy by dampening inflammation, strongly contributes to the idea that autophagy might represent a druggable system for the development of novel pharmacological tools that might represent an attractive strategy for the treatment of obesity and metabolic disorders.

Autophagy and the unfolded protein response shape the non-alcoholic fatty liver landscape: decoding the labyrinth

The incidence of nonalcoholic fatty liver disease (NAFLD) is on the rise, mirroring a global surge in diabetes and metabolic syndrome, as its major leading causes. NAFLD represents a spectrum of liver disorders, ranging from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH), which can potentially progress to cirrhosis and hepatocellular carcinoma (HCC). Mechanistically, we know the unfolded protein response (UPR) as a protective cellular mechanism, being triggered under circumstances of endoplasmic reticulum (ER) stress. The hepatic UPR is turned on in a broad spectrum of liver diseases, including NAFLD. Recent data also defines molecular mechanisms that may underlie the existing correlation between UPR activation and NAFLD. More interestingly, subsequent studies have demonstrated an additional mechanism, i.e. autophagy, to be involved in hepatic steatosis, and thus NAFLD pathogenesis, principally by regulating the insulin sensitivity, hepatocellular injury, innate immunity, fibrosis, and carcinogenesis. All these findings suggest possible mechanistic roles for autophagy in the progression of NAFLD and its complications. Both UPR and autophagy are dynamic and interconnected fluxes that act as protective responses to minimize the harmful effects of hepatic lipid accumulation, as well as the ER stress during NAFLD. The functions of UPR and autophagy in the liver, together with findings of decreased hepatic autophagy in correlation with conditions that predispose to NAFLD, such as obesity and aging, suggest that autophagy and UPR, alone or combined, may be novel therapeutic targets against the disease. In this review, we discuss the current evidence on the interplay between autophagy and the UPR in connection to the NAFLD pathogenesis.

Endoplasmic Reticulum Stress and Its Impact on Adipogenesis: Molecular Mechanisms Implicated

Endoplasmic reticulum (ER) stress plays a pivotal role in adipogenesis, which encompasses the differentiation of adipocytes and lipid accumulation. Sustained ER stress has the potential to disrupt the signaling of the unfolded protein response (UPR), thereby influencing adipogenesis. This comprehensive review illuminates the molecular mechanisms that underpin the interplay between ER stress and adipogenesis. We delve into the dysregulation of UPR pathways, namely, IRE1-XBP1, PERK and ATF6 in relation to adipocyte differentiation, lipid metabolism, and tissue inflammation. Moreover, we scrutinize how ER stress impacts key adipogenic transcription factors such as proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding proteins (C/EBPs) along with their interaction with other signaling pathways. The cellular ramifications include alterations in lipid metabolism, dysregulation of adipokines, and aged adipose tissue inflammation. We also discuss the potential roles the molecular chaperones cyclophilin A and cyclophilin B play in adipogenesis. By shedding light on the intricate relationship between ER stress and adipogenesis, this review paves the way for devising innovative therapeutic interventions.