We generated the human induced pluripotent stem cell (iPSC) line BIHi261-A from dermal fibroblasts of a patient with severe early-onset obesity caused by a homozygous truncating mutation in the POMC gene (W84X). Reprogramming was performed using a non-integrating, RNA-based vector expressing key pluripotency factors. The resulting iPSC line exhibited typical morphology, expressed markers of undifferentiated cells, maintained a normal karyotype, and demonstrated the capacity to differentiate into cell types of all three germ layers. BIHi261-A provides a valuable tool for studying the molecular mechanisms of POMC-related obesity and for developing potential therapeutic strategies.

Monogenic obesity, characterized by severe, early-onset obesity due to single-gene defects, often resists traditional weight management strategies. This report presents real-life experiences on the efficacy and safety of setmelanotide, an MC4R agonist, in 4 prepubertal children (ages 3-9) with LEPR and POMC deficiencies. Findings indicate that setmelanotide is effective at lower doses in our patients with POMC deficiency (0.3-0.5 mg/day) than the patients with LEPR deficiency (2.5 mg/day). Treatment was generally well-tolerated, with injection site reactions and hyperpigmentation as common side effects. As novel findings, gonadotropin-related effects such as hypothalamo-pituitary-gonadal axis activation and testicular descent were observed in 2 patients. Growth deceleration was noted in 2 children, and recovery from central hypothyroidism in 1 patient with POMC deficiency. Overall, setmelanotide appears to be effective and well-tolerated in young children with monogenic obesity. However, further studies are necessary to evaluate the long-term effects of early intervention on growth and pubertal development.

G-protein-signaling modulator 1 (GPSM1) has been proved the potential role in brain tissues, however, whether GPSM1 in hypothalamic nuclei, especially in POMC neurons is essential for the proper regulation of whole-body energy balance remains unknown. The aim of our current study was to explore the role of GPSM1 in POMC neurons in metabolic homeostasis. We generated POMC neuron specific GPSM1 deficiency mice and subjected them to a High Fat Diet to monitor metabolic phenotypes in vivo. By using various molecular, biochemical, immunofluorescent, immunohistochemical analyses, and cell culture studies to reveal the pathophysiological role of GPSM1 in POMC neurons and elucidate the underlying mechanisms of GPSM1 regulating POMC neurons activity. We demonstrated that mice lacking GPSM1 in POMC neurons were protected against diet-induced obesity, glucose dysregulation, insulin resistance, and hepatic steatosis. Mechanistically, GPSM1 deficiency in POMC neurons induced enhanced autophagy and improved leptin sensitivity through PI3K/AKT/mTOR signaling, thereby increasing POMC expression and α-MSH production, and concurrently enhancing sympathetic innervation and activity, thus resulting in decreased food intake and increased brown adipose tissue thermogenesis. Our findings identify a novel function of GPSM1 expressed in POMC neurons in the regulation of whole-body energy balance and metabolic homeostasis by regulating autophagy and leptin sensitivity, which suggests that GPSM1 in the POMC neurons could be a promising therapeutic target to combat obesity and obesity-related metabolic disorders.

The rising prevalence of obesity has become a worldwide health concern. Obesity usually occurs when there is an imbalance between energy intake and energy expenditure. However, energy expenditure consists of several components, including metabolism, physical activity, and thermogenesis. Toll-like receptor 4 (TLR4) is a transmembrane pattern recognition receptor, and it is abundantly expressed in the brain. Here, we showed that pro-opiomelanocortin (POMC)-specific deficiency of TLR4 directly modulates brown adipose tissue thermogenesis and lipid homeostasis in a sex-dependent manner. Deleting TLR4 in POMC neurons is sufficient to increase energy expenditure and thermogenesis resulting in reduced body weight in male mice. POMC neuron is a subpopulation of tyrosine hydroxylase neurons and projects into brown adipose tissue, which regulates the activity of sympathetic nervous system and contributes to thermogenesis in POMC-TLR4-KO male mice. By contrast, deleting TLR4 in POMC neurons decreases energy expenditure and increases body weight in female mice, which affects lipolysis of white adipose tissue (WAT). Mechanistically, TLR4 KO decreases the expression of the adipose triglyceride lipase and lipolytic enzyme hormone-sensitive lipase in WAT in female mice. Furthermore, the function of immune-related signaling pathway in WAT is inhibited because of obesity, which exacerbates the development of obesity reversely. Together, these results demonstrate that TLR4 in POMC neurons regulates thermogenesis and lipid balance in a sex-dependent manner.

Examine Setmelanotide use in patients with rare genetic variants that disrupt the melanocortin pathway. Between February 2017 and September 2018, 10 participants with pro-opiomelanocortin (POMC)/ proprotein convertase subtilisin/kexin type 1 (PCSK1) deficiency and 11 participants with leptin receptor (LEPR) deficiency were enrolled in open-label, phase 3 trials at 10 centers in the United States and internationally to assess the efficacy and safety of the melanocortin-4 receptor (MC4R) agonist Setmelanotide. 80% of POMC participants and 45% of LEPR participants achieved at least 10% weight loss at 1 year. Significant changes in hunger scores were seen for both cohorts as well. Setmelanotide was well tolerated with injection site reactions and hyperpigmentation being the most common adverse events reported. As a result, Setmelanotide was approved by the U.S. FDA in 2020 for chronic weight management in adult and pediatric patients ≥6 years of age with POMC, LEPR, or PCSK1 deficiency. In 2022, its approval was extended to include patients with Bardet-Biedel syndrome (BBS) after phase 3 trial data showed that, on average, Setmelanotide treatment resulted in a BMI loss of 7.9% for the 44 BBS participants. Rare genetic variants such as POMC, LEPR, and PCSK1 deficiency disrupt MC4R pathway signaling, resulting in severe early-onset obesity, hyperphagia, and increased risk for metabolic co-morbidities. Patients with BBS also demonstrate severe early-onset obesity and hyperphagia, due in part to defective MC4R signaling. Setmelanotide has shown promising benefits in improving satiety scores and weight-related outcomes in patients with these early-life genetic obesity conditions, although longer-term studies are needed.