Proprotein Convertase Subtilisin/kexin Type 1 Research Articles

Setmelanotide (Imcivree)


 CADTH reimbursement reviews are comprehensive assessments of the clinical effectiveness and cost-effectiveness, as well as patient and clinician perspectives, of a drug or drug class.
 The assessments inform non-binding recommendations that help guide the reimbursement decisions of Canada's federal, provincial, and territorial governments, with the exception of Quebec.
 This review assesses setmelanotide (Imcivree), 10 mg/mL solution in a 1 mL multiple-dose vial, administered through once-daily SC injection.
 Indication: For weight management in adult and pediatric patients aged 6 years and older with obesity due to:
 
 Bardet-Biedl syndrome
 Genetically confirmed biallelic pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency due to variants interpreted as pathogenic, likely pathogenic, or of uncertain significance.
 
 

Type 2 Diabetes Mellitus Serum Biomarker Levels and Associated Single Nucleotide Polymorphisms in a South African Population

Type 2 diabetes mellitus (T2DM) is a metabolic disorder with multiple causes. The prevalence of T2DM is on the rise, however, on the African continent, nearly 70% of all T2DM cases go undiagnosed. T2DM places a great burden on the already stretched healthcare systems. Current tests do not provide predictive measures in terms of the possible onset of the disease. Biomarker and gene analysis have been used to predict the onset of the disease, but this has seen very limited use in the African population groups. Identification of variances in biomarkers and subsequent genetic aberrations at early diagnosis could enable clinical focus on patients more likely to develop insulin resistance. The aim of the study was to compare T2DM-associated biomarker levels between T2DM patients and non-T2DM participants and identify genetic variances in single nucleotide polymorphisms (SNPs) associated with the biomarkers. Two cohorts (n = 78) were screened for associated biomarkers using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. The results of this analysis were used to select SNPs in genes associated with the screened biomarkers. The molecular genotyping was completed using quantitative polymerase chain reaction (qPCR) assays. The biomarker analysis revealed significant statistical differences between four of the ten screened biomarkers: Glucose-dependent insulinotropic polypeptide (GIP) (p = 0.0004), resistin (p = 0.0398), visfatin (p = 0.0009), and glucagon (p = 0.0034). The SNPs selected for molecular genotyping were rs6235 in proprotein convertase subtilisin/kexin type 1 (PCSK1) and rs2208203 in proprotein convertase subtilisin/kexin type 2 (PCSK2). Both these genes are involved in the biosynthesis of various biomarkers that were screened. The results from the molecular genotyping failed to show any significant difference between the control and T2DM case groups. While some biomarkers were shown to have significant statistical differences between the two study cohorts, more work needs to be conducted to understand the role of each biomarker in T2DM.

Calnuc-derived nesfatin-1-like peptide is an activator of tumor cell proliferation and migration.

Calnuc (nucleobindin-1, nucb1) is a Ca2+ -binding protein involved in the etiology of many human diseases. To understand the functions of calnuc, we have identified a nesfatin-1-like peptide (NLP) in its N terminus that is proteolyzed by a convertase enzyme in the secretory granules of cells. Mutational studies confirm the presence of a proteolytic cleavage site for proprotein convertase subtilisin/kexin type 1 (PCSK1). We demonstrate that NLP regulates Gαq-mediated intracellular Ca2+ dynamics, likely via a G-protein-coupled receptor. NLP treatment to carcinoma cell lines (SCC131 cells) promotes the expression of regulators of cell cycle, proliferation, and clonogenicity by the AKT/mTOR pathway. NLP is causative of augmented migration and epithelial-mesenchymal transition (EMT), illustrating its metastatic propensity and establishing its tumor promotion ability.

A Review of Genes Associated with Obesity Susceptibility: Findings from Association Studies

Obesity is described as the accumulation of excess body fat. Several health issues are caused by excess fat, including cancer, type 2 diabetes, and cardiovascular disease. Additionally, obesity rates among schoolchildren and young adults are rising globally, putting young people at risk of chronic diseases. Genetics, epigenetic modification, epigenomics, and environmental factors influence inheritance patterns significantly. This systematic study aimed to classify and investigate the polymorphisms of novel candidate obesity genes. Several genes have been suggested, includingat mass and obesity-associated gene (FTO), leptin gene (LEP), leptin receptor gene (LEPR), peroxisome proliferatoractivated receptor gamma gene (PPARG), melanocortin 4 receptor (MC4R), insulin-induced gene 2 (INSIG2), proprotein convertase subtilisin/kexin type 1 (PCSK1), adrenoceptor beta 2 (ADRB2), and uncoupling protein 2 (UCP2). The study’s literature review identified genes in scientific papers published in databases such as Web of Science, PubMed, Google Scholar, Embase, and others over the past three decades. There is evidence that genetic variations contribute to childhood obesity, adolescent obesity, and young adult obesity. Identifying functional differences and further defining the implicated molecularly and physiologically involved genes andpathways in efficient therapeutic approaches in fighting. Technological advances have recently demonstrated that genetic changes and mutations can be used as biological markers, risk indicators, and therapeutic targets.

Autosomal Dominant Familial Neurohypophyseal Diabetes Insipidus in Three Generations

Familial neurohypophysial diabetes insipidus (FNDI), an autosomal dominant disorder, comes in many forms that are differentiated by the inheritance pattern and the underlying genetic lesion. The disease is caused by mutations in the vasopressin-neurophysin 2- copeptin protein (AVP-NPII), in wolframin (WFS1) or in proprotein convertase subtilisin/kexin type 1 (PCSK1) genes. Materials and methods: In this study, we report a case of familial neurohypophyseal DI in three generations; followed in unit of the endocrinology, diabetology, metabolic diseases and nutrition department of the Mohammed VI University Hospital of Marrakesh. Results: This was a 45-year-old patient who had been suffering from polyuro-polydipsia syndrome since the age of 12, with daily urine volumes ranging from 8.0 to 15.0 litres, but had not seen a doctor. The patient was born without complications and had normal puberty. In the family history, three other members of the patient’s family have also had polypolypolydispic syndrome since adolescence, covering three generations, including the patient’s mother, her younger sister and daughter. A water restriction test was performed but the patient did not tolerate it. We completed with the minirin test with a good clinical response: urine concentrated with a volume of 500ml, and urinary osmolarity at H4 of 276.13 (Fig 2). As presented in (Fig 3), cranial MRI revealed a hypersignal region in the posterior pituitary lobe. Serum cortisol, thyroid function, and estrogen were all in the normal range The growth hormone (GH), insulin like growth factor (IGF)-1 levels and the genetic testing were not performed due to limited financial resources. After treatment with oral desmopressin 60 ug two times daily was started, the symptoms of polydipsia and polyuria were satisfactorily controlled.

OR10-1 Body Mass Index and Weight Reductions in Patients With Obesity Due to Heterozygous Variants in POMC, PCSK1, and LEPR After 1 Year of Setmelanotide

Abstract Background The melanocortin-4 receptor (MC4R) pathway is a key regulator of energy balance. Heterozygous variants of the genes for proopiomelanocortin (POMC), leptin receptor (LEPR), and proprotein convertase subtilisin/kexin type 1 (PCSK1) upstream of MC4R can result in impaired signaling in the MC4R pathway. This impaired signaling can lead to hyperphagia and early-onset, severe obesity. Setmelanotide (SET), an MC4R agonist, reduced weight and hunger after 3 months in patients with obesity due to these heterozygous variants in an earlier Phase 2 study. The current analysis is the first to assess continued efficacy of an additional year of SET treatment in patients with obesity due to heterozygous affectation of POMC, PCSK1, and LEPR. Methods Patients aged ≥6 years with obesity due to heterozygous variants in POMC, PCSK1, and LEPR were eligible for this long-term extension (LTE) trial (NCT03651765) after completing an index trial in which they received SET and demonstrated clinical benefit and acceptable safety as determined by the investigator. Patients received a minimum of 4 months of SET treatment in the index trial and began the LTE immediately following the completion of the index trial. Study visits occurred every 3 months and evaluated changes in body weight measures and assessed safety and tolerability. The current analysis reports outcomes after 1 year total of SET treatment across the index and LTE trials, relative to index trial baseline. Results As of October 29, 2021, 35 patients with obesity heterozygous for POMC, PCSK1, and LEPR had enrolled in the index trial, with 16, 17, and 17 patients continuing into the LTE trial and receiving at least 6, 9, and 12 months of treatment with SET, respectively. At index trial baseline, mean (standard deviation [SD]) body mass index (BMI) for all index trial patients was 50.26 (9.41) kg/m2, body weight in patients ≥18 years old was 142.97 (28.70) kg, and BMI Z score in patients <18 years old was 4.04 (0.65). Mean (SD) percent change in BMI was −6.93% (9.13%; n=16), −8.14% (10.13%; n=17), and −7.83% (9.69%; n=17) after 6, 9, and 12 months of treatment, respectively. Of 15 patients ≥18 years old, the mean (SD) percent change in body weight was −10.24% (7.90%; n=15) after 12 months. For the 1 patient <18 years old, mean change in BMI Z score was 0.64 after 12 months. No new safety concerns emerged during the LTE and 1 patient discontinued due to an adverse event, likely unrelated to treatment. Conclusions Treatment with SET had continued efficacy in patients with obesity due to heterozygous variants in POMC, PCSK1, and LEPR after 1 year of treatment. These data support the continued investigation of SET in these patients, which is underway in the Phase 3 EMANATE trial (NCT05093634). Presentation: Sunday, June 12, 2022 11:00 a.m. - 11:15 a.m.

Modulation of PC1/3 activity by a rare double-site homozygous mutation.

Preprotein convertase 1/3 deficiency is a rare autosomal recessive disorder in which patients present with malabsorptive diarrhea and a series of symptoms of endocrine disorders such as polydipsia, reactive hypoglycemia, growth hormone deficiency, hypothyroidism, adrenal insufficiency, and early onset obesity. In its essence, pituitary hormone deficiency is caused by insufficient cleavage of pituitary prohormones. Here, we describe a female child with a rare double-site homozygous mutation in PCSK1 (Proprotein convertase subtilisin/kexin-type 1) gene, and thereby intend to investigate the relationship between these novel mutation sites and changes in protein synthesis and function. We tested this patient's blood and urine fecal indicators of infection, blood electrolytes, and relevant endocrine hormone levels in the laboratory. Next Generation Sequencing was applied to screen the patient's DNA. Western Blot was performed to evaluate the mutant protein's expression. The enzymatic activity was measured as the rate of cleavage of a synthetic fluorogenic substrate in a specific solution. We found that this patient presented shortly after birth with uncorrectable diarrhea and symptoms of metabolic acidosis with hypothyroidism. Next Generation Sequencing revealed that a rare double-site homozygous missense mutation, c.763G > A (p.G255R) and c.758C > T (p.S253L), were detected in exon 7 of PCSK1 (Proprotein convertase subtilisin/kexin-type 1) gene on chromosome 5 of the patient. Western blotting revealed that there was no significant decrease in protein synthesis levels in the mutant phenotype compared to the wild type. Compared with WT type, the proteins expressed by the mutations showed a significant decrease in the enzyme activity towards the fluorescent substrates. However, neither the single site mutation p.S253L or p.G255R, nor the double-site mutation of both, all showed no significant differences from each other. These two missense mutations have not been reported before, and it is even rarer to find homozygous variation of two sites in one patient. This study identifies two novel mutations for the first time and further investigates the changes in protein synthesis and enzyme activity, providing a new pathway to continue to explore the pathogenesis of diseases associated with the function of PC1/3.

Correlation of PCSK1 with nonalcoholic fatty liver disease in a Han Chinese population: a case-control observational study

Objective: This study aimed to investigate the association between single-nucleotide polymorphisms (SNPs) of PCSK1 (proprotein convertase subtilisin/kexin type 1) related to obesity and nonalcoholic fatty liver disease (NAFLD). Methods: In this case-control observational study, four candidate SNPs (rs6234, rs155971, rs6232, rs3811951) of PCSK1 were genotyped in 732 NAFLD patients and 823 healthy control participants, all of whom were of ethnic Han Chinese descent. All participants came from Shanghai, China, and joined our study during 2015 to 2016. The frequencies of each allele and genotype, paired linkage disequilibrium, and haplotype were calculated on the SHEsis platform. In addition to SHEsis, five different genetic models (codominant, dominant, recessive, overdominant, and log-additive) were employed to identify the correlation between genotype frequency and NAFLD. This study was approved by the Medical Ethics Committee of Shanghai University of Traditional Chinese Medicine (approved No. 2017LCSY069). Results: In a comparison of NAFLD patients and healthy participants, none of the four PCSK1 SNPs were significantly correlated with the occurrence of NAFLD (P > 0.05), in either genotypic or allelic distribution. The recessive model of rs3811951 appeared to show a correlation (odds ratio = 1.077; 95% confidence interval = 0.924–1.256; P = 0.04), but there was no statistical significance after Bonferroni correction (P corr > 0.0125). Conclusions: Four obesity-related PCSK1 SNPs (rs6234, rs155971, rs6232, rs3811951) showed no significant correlation with the development of NAFLD in a Han Chinese population.

Setmelanotide in obesity: a profile of its use

Subcutaneous setmelanotide (IMCIVREE®), a melanocortin-4 receptor agonist, meets a previously unmet need and thus represents an important advancement in the management of patients with pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1) or leptin receptor (LEPR) deficiency obesity. Setmelanotide is the first approved treatment in patients aged ≥ 6 years with these conditions. In two single-arm, open-label, multicentre, phase III trials, subcutaneous setmelanotide was effective in reducing body weight by at least 10% from baseline after approximately 1 year of treatment at individualised therapeutic doses in patients aged ≥ 6 years with POMC, PCSK1 or LEPR deficiency obesity. Other outcomes relating to weight loss and self-reported hunger scores were also improved with setmelanotide therapy. Setmelanotide was generally well tolerated in clinical trials.

Natural History of Obesity Due to POMC, PCSK1, and LEPR Deficiency and the Impact of Setmelanotide.

ContextRare homozygous or biallelic variants in POMC, PCSK1, and LEPR can disrupt signaling through the melanocortin-4 receptor (MC4R) pathway, resulting in hyperphagia and severe early-onset obesity. In pivotal Phase 3 clinical trials, treatment with the MC4R agonist setmelanotide reduced hunger and weight in patients with obesity due to proopiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency.ObjectiveTo characterize the historical weight trajectory in these patients.MethodsThis analysis included data from 2 pivotal single-arm, open-label, Phase 3 trials (NCT02896192, NCT03287960). These were multicenter trials. Patients had obesity due to POMC/PCSK1 or LEPR deficiency. During the trial, patients were treated with setmelanotide. Historical data on measured weight and height were obtained during screening.ResultsA total of 17 patients (POMC, n = 8; PCSK1, n = 1; LEPR, n = 8) with historical weight and height data were included in this analysis. Before setmelanotide treatment, patients with obesity due to POMC/PCSK1 or LEPR deficiency were above the 95th percentile for weight throughout childhood, demonstrated continuous weight gain, and did not show long-term weight loss upon interventions (eg, diet, surgery, exercise). Setmelanotide treatment attenuated weight and body mass index trajectories over the observation period of 1 year.ConclusionIn patients with POMC, PCSK1, or LEPR deficiency, traditional interventions for weight loss had limited impact on the trajectory of severe early-onset obesity. However, setmelanotide treatment attenuated weight and body mass index trajectories and led to weight loss associated with health benefits in most individuals.

Application of gene therapy for reversing T-cell dysfunction in cancer

T cells are the key players of antitumor function that sense antigens produced by tumor cells and specifically target cancer cells to induce cell death. Therefore, it is widely understood that T cells are critical for cancer immunotherapy. Many recent studies discovered that T cells enter a dysfunctional or inactivated state. Cancer cells induce functional impairment of T cells by sustained expression of inhibitory receptors in T cells. Therefore, reversing T-cell dysfunction is critical for increasing the efficacy of tumor immunotherapy. In this research, we analyzed the cellular inhibition and activation of T cells using two cell line models: Jurkat (T cells) and MDA-MB-231 (breast cancer cells). We hypothesized that the knockdown of T-cell inhibition-causing genes might reverse the T-cell dysfunction caused by cancer cells. Therefore, we targeted Proprotein Convertase Subtilisin/Kexin Type 1 (PCSK1) gene in T cells and programmed death-ligand 1 (CD274) in cancer cells. We used small interference RNA (siRNA) to knock down the target gene. We used four μg/ml of lipopolysaccharide (LPS) to activate Jurkat cells. MDA-MB-231 co-culture with Jurkat cells reduced IL-2 expression level on Jurkat cells. We found that siRNA targeting CD274 in MDA-MB-231 reversed the reduced IL-2 expression level on Jurkat induced by Jurkat and MDA-MB-231 co-culture. Also, when the PCSK1 knockdown Jurkat cells and CD274 knockdown MDA-MB-231 were co-cultured, the most effective recovery of IL-2 expression level in Jurkat cells was observed. Overall, this study provides a novel strategy for reactivating T cells whose activation has been suppressed from cancer cells.

Effects of Setmelanotide in Patients With POMC, PCSK1, or LEPR Heterozygous Deficiency Obesity in a Phase 2 Study

Abstract Introduction: Setmelanotide is a melanocortin 4 receptor (MC4R) agonist being investigated for chronic weight management in patients with rare genetic diseases of obesity caused by impairment of the MC4R pathway. The objective of this analysis was to assess the efficacy and safety of setmelanotide in patients with partial insufficiency in the MC4R pathway due to heterozygous mutations in the POMC, PCSK1, or LEPR genes. Methods: This was an open-label, single-arm, Phase 2 study of setmelanotide in rare genetic diseases of obesity, including proopiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) heterozygous deficiency obesity (NCT03013543). Patients aged ≥6 years with POMC, PCSK1, or LEPR heterozygous deficiency obesity received once-daily setmelanotide, which was titrated for 4 weeks to establish the therapeutic dose of 3 mg daily. Treatment at the therapeutic dose continued for an additional 12 weeks. The primary endpoint was mean percent change from baseline in body weight at Month 3. Hunger scores and adverse events (AEs) were secondary endpoints. A responder was defined as having ≥5% weight loss from baseline at Month 3. Results: A total of 35 patients were included in this analysis, with mean (standard deviation) age of 39.5 (17.6) years and body mass index of 50.3 (9.4) kg/m2. Across all patients, the mean percent change in body weight from baseline to Month 3 was −3.7% (90% confidence interval [CI], −5.3% to −2.1%; n=35). A total of 34.3% of patients (12/35) achieved the responder threshold of ≥5% weight loss from baseline at Month 3. The mean percent change in body weight from baseline to Month 3 was −10.1% (90% CI, −12.4% to −7.9%; n=12) and −0.4% (90% CI, −1.2% to −0.5%; n=23) for responders and nonresponders, respectively. The mean percent change in most hunger score from baseline to Month 3 was −4.4% (90% CI, −5.7% to −3.2%; n=10) and −2.3% (90% CI, −3.2% to −1.5%; n=23) for responders and nonresponders, respectively. Among responders, 4 (33%) had variants that were considered pathogenic/likely pathogenic per American College of Medical Genetics criteria. All patients experienced at least 1 AE. Overall, the most common treatment-emergent AEs were skin hyperpigmentation (51.4%), nausea (48.6%), and injection site pruritis (37.8%). One patient had serious AEs of acute myocardial infarction and gastrointestinal hemorrhage that were considered unrelated to setmelanotide. No AEs led to death. Conclusions: Setmelanotide was associated with reduced body weight and hunger scores in patients with POMC, PCSK1, or LEPR heterozygous deficiency obesity. While the overall mean percent decrease in body weight may have been less than that previously reported in patients with homozygous or compound heterozygous variants, setmelanotide may be a viable treatment option for some patients with POMC, PCSK1, or LEPR heterozygous deficiency obesity.

Timing of Onset of Adverse Events With Setmelanotide, an MC4R Agonist, in Patients With Severe Obesity Due to LEPR or POMC Deficiency

Introduction: Setmelanotide is a melanocortin 4 receptor agonist indicated for chronic weight management in patients with obesity due to proopiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency. This analysis aimed to assess the timing of the onset of adverse events (AEs) of special interest in patients with POMC/PCSK1 or LEPR deficiency obesity treated with setmelanotide. Methods: The timing of AE onset with setmelanotide was evaluated in a pooled set of patients with POMC/PCSK1 or LEPR deficiency who received setmelanotide in Phase 2 (RM-493-011 [NCT02507492]) or Phase 3 (RM-493-012 [NCT02896192] and RM-493-015 [NCT03287960]) clinical trials. Patients in the Phase 2 investigator-initiated trial (Charité Universitätsmedizin Berlin) received open-label setmelanotide for 12 to 13 weeks followed by an extension study for eligible patients. The Phase 3 trials included a 12-week open-label phase, an 8-week placebo-controlled phase, and a subsequent 32-week open-label phase, for a total treatment length of at least 1 year. AEs were assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events (version 4.0). AEs of special interest were defined as those related to treatment-emergent AEs (TEAEs) commonly occurring with setmelanotide (hyperpigmentation disorders, disturbances in sexual arousal, nausea, vomiting, injection site reactions [ISRs]). Results: As of November 10, 2020, 35 patients (15 POMC, 2 PCSK1, 18 LEPR) were enrolled and included across the 3 trials; 2 patients in the Phase 2 trial were ongoing treatment as of the cutoff. Daily setmelanotide dose ranged from 0.25 to 3.0 mg. All patients experienced ≥1 TEAE, the most common being skin hyperpigmentation (85.7%), injection site erythema (68.6%), nausea (57.1%), and headache (51.4%). For AEs of special interest, hyperpigmentation disorders occurred in 85.7% of patients (30/35), disturbances in sexual arousal in 17.1% (6/35), nausea in 57.1% (20/35), vomiting in 28.6% (10/35), and ISRs in 88.6% (31/35). The onset of most hyperpigmentation disorder (34/53 events; 64.2%) and disturbances in sexual arousal(6/11 events; 54.6%) AEs were during Month 1 after starting setmelanotide. Onset of nausea and vomiting were most frequent during Month 1 of treatment (nausea: 12/34 events [35.3%]; vomiting: 6/19 events [31.6%]). ISRs occurred throughout the trial, with 41.6% (91/219 events) having an onset within Month 1 of treatment. Eighteen serious AEs occurred, none were interpreted as related to the study drug. Conclusions: In patients with POMC/PCSK1 or LEPR deficiency obesity who received setmelanotide treatment, the onset of AEs of special interest in any month was generally highest during Month 1 of treatment, with fewer events occurring during subsequent months. Apart from hyperpigmentation, all AEs occurred intermittently.

Setmelanotide: First Approval

Setmelanotide (IMCIVREE™, Rhythm Pharmaceuticals) is a melanocortin-4 (MC4) receptor agonist developed for the treatment of obesity arising from proopiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency. The drug has received its first approval in the USA for chronic weight management in patients 6 years and older with obesity caused by POMC, PCSK1 and LEPR deficiency and has been granted PRIority MEdicines (PRIME) designation by the European Medicines Agency for the treatment of obesity and the control of hunger associated with deficiency disorders of the MC4 receptor pathway. Setmelanotide is also being developed in other rare genetic disorders associated with obesity including Bardet-Biedl Syndrome, Alström Syndrome, POMC and other MC4R pathway heterozygous deficiency obesities, and POMC epigenetic disorders. This article summarizes the milestones in the development of setmelanotide leading to this first approval for obesity caused by POMC, PCSK1 and LEPR deficiency.

Kisspeptin and the Genetic Obesity Interactome.

Kisspeptin (encoded by the KISS1 gene in humans) is an excitatory neuromodulatory peptide implicated in multiple homeostatic systems, including anti-oxidation, glucose homeostasis, nutrition, locomotion, etc. Therefore, in the current obesity epidemic, kisspeptin is gaining increasing interest as a research objective. To construct an updated interactome of genetic obesity, including the kisspeptin signal transduction pathway. Kisspeptin and obesity-related genes or gene products were extracted from the biomedical literature, and a network of functional associations was created. The generated network contains 101 nodes corresponding to gene/gene products with known and/or predicted interactions. In this interactome, KISS1 and KISS1R are connected directly to the luteinizing hormone receptor (LHCGR), gonadotropin-releasing hormone receptor (GNRH1), and indirectly, through the latter, to proopiomelanocortin (POMC), glucagon, leptin (LEP), and/or pro-protein convertase subtilisin/kexin-type 1 (PCSK1), all of which are critically implicated in obesity disorders. Our updated obesidome includes kisspeptin and its connections to the genetic obesity signalosome with 12 major hubs: glucagon (GCG), insulin (INS), arginine vasopressin (AVP), G protein subunit beta 1 (GNB1) and proopiomelanocortin (POMC), melanocortin 4 receptor (MC4R), leptin (LEP), gonadotropin-releasing hormone 1 (GNRH1), adrenoceptor beta 2 and 3 (ADRB2-3), glucagon-like peptide 1 receptor (GLP1R), and melanocortin 3 receptor (MC3R) genes were identified as major "hubs" for genetic obesity, providing novel insight into the body's energy homeostasis.

Association of PCSK1 gene polymorphisms with abdominal fat content in broilers.

Protein proteolytic enzymes (Proprotein Convertase, PC) is a Ca2+ -dependent serine protease family, whose main function is to cleave precursors of biologically inactive proteins or peptide chains into active functional molecules. Proprotein convertase subtilisin/kexin type 1 (PCSK1) gene is mainly expressed in nerve and endocrine tissues. In this study, PCSK1 was selected as an important candidate gene for abdominal fat content in broilers. We cloned the exon region of chicken PCSK1 gene and found six single-nucleotide polymorphisms (SNPs). Association analysis was carried out and we found that the polymorphisms of these six SNPs were significantly associated with abdominal fat content in G19 and G20 populations. Five of these SNPs were significantly associated with abdominal fat content in G19 and G20 combined population. The polymorphism of these five SNPs was significantly correlated with the abdominal fat content of AA broilers. Together, our study demonstrated that c.927T>C, c.1880C>T, c.*900G>A, and c.*1164C>T were significantly associated with abdominal fat content in populations used in this study, which means that these SNPs in PCSK1 gene could be used as candidate markers to select lean broiler lines.

Pax4 synergistically acts with Pdx1, Ngn3 and MafA to induce HuMSCs to differentiate into functional pancreatic β-cells.

It has been indicated that the combination of pancreatic and duodenal homeobox 1 (Pdx1), MAF bZIP transcription factor A (MafA) and neurogenin 3 (Ngn3) was able to reprogram various cell types towards pancreatic β-like cells (pβLCs). Paired box 4 (Pax4), a transcription factor, has a key role in regulating the maturation of pancreatic β-cells (pβCs). In the present study, it was investigated whether Pax4 is able to synergistically act with Pdx1, Ngn3 and MafA to induce human umbilical cord mesenchymal stem cells (HuMSCs) to differentiate into functional pβCs in vitro. HuMSCs were isolated, cultured and separately transfected with adenovirus (Ad) expressing enhanced green fluorescence protein, Pax4 (Ad-Pax4), Pdx1+MafA+Ngn3 (Ad-3F) or Ad-Pxa4 + Ad-3F. The expression of C-peptide, insulin and glucagon was detected by immunofluorescence. The transcription of a panel of genes was determined by reverse transcription-quantitative PCR, including glucagon (GCG), insulin (INS), NK6 homeobox 1 (NKX6-1), solute carrier family 2 member 2 (SLC2A2), glucokinase (GCK), proprotein convertase subtilisin/kexin type 1 (PCSK1), neuronal differentiation 1 (NEUROD1), ISL LIM homeobox 1 (ISL 1), Pax6 and PCSK type 2 (PCSK2). Insulin secretion stimulated by glucose was determined using ELISA. The results suggested that, compared with Ad-3F alone, cells co-transfected with Ad-Pax4 and Ad-3F expressed higher levels of INS and C-peptide, as well as genes expressed in pancreatic β precursor cells, and secreted more insulin in response to high glucose. Furthermore, the expression of GCG in cells transfected with Ad-3F was depressed by Ad-Pax4. The present study demonstrated that Pax4 was able to synergistically act with the transcription factors Pdx1, Ngn3 and MafA to convert HuMSCs to functional pβLCs. HuMSCs may be potential seed cells for generating functional pβLCs in the therapy of diabetes.

Hyperphagia and Obesity in Prader⁻Willi Syndrome: PCSK1 Deficiency and Beyond?

Prader–Willi syndrome (PWS) is a complex genetic disorder that, besides cognitive impairments, is characterized by hyperphagia, obesity, hypogonadism, and growth impairment. Proprotein convertase subtilisin/kexin type 1 (PCSK1) deficiency, a rare recessive congenital disorder, partially overlaps phenotypically with PWS, but both genetic disorders show clear dissimilarities as well. The recent observation that PCSK1 is downregulated in a model of human PWS suggests that overlapping pathways are affected. In this review we will not only discuss the mechanisms by which PWS and PCSK1 deficiency could lead to hyperphagia but also the therapeutic interventions to treat obesity in both genetic disorders.

Genetic basis of obesity: a review

Obesity is a state of “positive” energy balance when energy intake in is much greater than energy expenditure. The familial aggregation of body size was first published by Sir Francis Galton in 1889, which become a well-established risk factor for childhood obesity. Obesity is often allied with insulin resistance, dyslipidemia and cardiovascular disease. Monogenic obesity includes the involvements of Leptin (LEP) gene, leptin receptor(LEPR), Proopiomelanocortin (POMC), Melanocortin-4 receptor (MC4R), single-minded gene 1 (SIM 1), Proprotein convertase subtilisin/ kexin type 1 (PCSK1), Neuropeptide Y (NPY). Polygenic obesity is due to Adrenoceptor beta 1 (ADRB1), ADRB2, ADRB3, Uncoupling protein 1(UCP1), UCP2, UCP3. Monogenic and polygenic obesity; pleiotropic syndromes, chromosomal rearrangement are different types of obesity with genetic cause. Surprisingly all “obesity genes” carriers do not become overweight, and exercise, maintaining healthy routine is a significant contributing factor to nullify genetic prediposition.Journal of Biomedical Sciences, Vol. 3, No.2, 2016, Page: 24-28

Farnesoid X Receptor (FXR) Interacts with Camp Response Element Binding Protein (CREB) to Modulate Glucagon-Like Peptide-1 (7–36) Amide (GLP-1) Secretion by Intestinal L Cell

Type II diabetes is a complex, chronic, and progressive disease. Glucagon-like peptide-1 (7-6) amide (GLP-1) is a gut hormone released from the L cells which stimulates insulin secretion, and promotes insulin gene expression and β-cell growth and differentiation. Elevated levels of hormone secreted by L cells are an important reason for diabetes improvement. GLP-1 secretion has been reported to be regulated by farnesoid X receptor (FXR), a transcriptional sensor for bile acids which also acts on glucose metabolism. Herein, we attempted to evaluate the effect of FXR on GLP-1 secretion in mouse enteroendocrine L cell lines, STC-1 and GLUTag, and to investigate the underlying mechanism. ELISA and Western blot assays were employed to examine the levels of GLP-1 and FXR, and the effect of FXR on GLP-1 secretion; online database, including BioGRID and KEGG were used to identify the potential interactions between FXR and proteins and involved pathways; GST pull-down and Co-Immunoprecipitation (Co-IP) assays were performed to validate FXR-CREB interaction; Luciferase reporter gene assays were used for CREB transcriptional activity determination. FXR inversely regulated GLP-1 secretion in the mouse enteroendocrine L cell lines, GLUTag and STC-1. A total of 24 nonredundant human proteins were shown to be related to FXR by BioGRID; KEGG pathway analysis showed that FXR was related to glucagon signaling pathway, particularly with the transcriptional activators CREB, PGC1α, Sirt1 and CBP. CREB could positively regulate GLP-1 secretion in GLUTag and STC-1 cells. FXR combined with CREB to inhibit its transcriptional activity, thus inhibiting proprotein convertase subtilisin/ kexin type 1 (PCSK1) protein level and GLP-1 secretion. In the present study, we demonstrated a negative regulation of GLP-1 secretion by FXR in L cell lines, GLUTag and STC-1; FXR exerts its function in L cells through interacting with CREB, a crucial transcriptional regulator of cAMP-CREB signaling pathway, to inhibit its transcriptional activity. Targeting FXR to rescue GLP-1 secretion may be a promising strategy for type II diabetes.