Introduction: Accumulation of fat in omental visceral adipose tissue (OVAT) is strongly linked to metabolic diseases. Our recent findings show a distinct and more accessible chromatin landscape of the visceral depot compared to its subcutaneous counterpart. Based on integrated analysis of chromatin accessibility and transcriptomics, we identified previously unrecognised genes linked with obesity. Here, we performed in-depth analyses of one of the candidates, HOOK1, and tested for depot-specific gene expression, correlation with clinical traits and regulatory mechanisms including DNA methylation. METHODS:We utilised intra-individually paired adipose tissue samples of human OVAT and subcutaneous adipose tissue (SAT) from our in-house cohort (N = 78). Gene expression was measured using real-time quantitative PCR and pyrosequencing was used to determine DNA methylation levels. Data were analysed for differential gene expression and DNA methylation differences between SAT and OVAT, along with correlation analyses with clinical variables related to obesity. Results were validated in adipose tissue samples from 1,618 donors of the Leipzig Obesity Biobank. RESULTS:We observed consistently higher HOOK1 gene expression in OVAT compared to SAT and successfully confirmed this effect direction in several validation cohorts. We further identified that HOOK1 gene expression correlated with body mass index and hip circumference. We discovered a relationship between DNA methylation of the HOOK1 promoter with clinical variables important for liver function. CONCLUSION:Our data show that HOOK1 gene expression is adipose tissue depot-specific. We observed that gene expression and DNA methylation are correlated to clinical variables of obesity, suggesting that HOOK1 may play a role in obesity and its sequelae. .
Biallelic variations in SREK1 reduce SNORD115/116 expression, linking severe obesity and Prader-Willi-like traits, offering genetic and molecular insights into a new form of syndromic obesity.
BACKGROUND:Obesity is a global health challenge and adipose tissue exhibits distinct depot-specific characteristics impacting differentially on the risk of metabolic comorbidities. METHODS:Here, we integrate chromatin accessibility (ATAC-seq) and gene expression (RNA-seq) data from intra-individually paired human subcutaneous (SAT) and omental visceral adipose tissue (OVAT) samples to unveil depot-specific regulatory mechanisms. FINDINGS:We identified twice as many depot-specific differentially accessible regions (DARs) in OVAT compared to SAT. SAT-specific regions showed enrichment for adipose tissue enhancers involving genes controlling extracellular matrix organization and metabolic processes. In contrast, OVAT-specific regions showed enrichment in promoters linked to genes associated with cardiomyopathies. Moreover, OVAT-specific regions were enriched for bivalent transcription start site and repressive chromatin states, suggesting a "lingering" regulatory state. Motif analysis identified CTCF and BACH1 as most significantly enriched motifs in SAT and OVAT-specific DARs, respectively. Distinct gene sets correlated with important clinical variables of obesity, fat distribution measures, as well as insulin, glucose, and lipid metabolism. INTERPRETATION:We provide an integrated analysis of chromatin accessibility and transcriptional profiles in paired human SAT and OVAT samples, offering new insights into the regulatory landscape of adipose tissue and highlighting depot-specific mechanisms in obesity pathogenesis. FUNDING:SS received EU-Scientia postdoctoral Fellowship and project funding from the European Union's Horizon 2020 Research and Innovation program under the Marie Skłodowska-Curie Grant, (agreement No. 801133). LlCP and TR were supported by Helse Sør-Øst grants to Y.B (ID 2017079, ID 278908). MB received funding from grants from the DFG (German Research Foundation)-Projekt number 209933838-SFB 1052 (project B1) and by Deutsches Zentrum für Diabetesforschung (DZD, Grant: 82DZD00601).
Obesity is a heritable disease, but its genetic basis is incompletely understood. Canine population history facilitates trait mapping. We performed a canine genome-wide association study for body condition score-a measure of obesity-in 241 Labrador retrievers. Using a cross-species approach, we showed that canine obesity genes are also associated with rare and common forms of obesity in humans. The lead canine association was within the gene DENN domain containing 1B (DENND1B). Each copy of the alternate allele was associated with ~7.5% greater body fat. We demonstrate a role for this gene in regulating signaling and trafficking of melanocortin 4 receptor, a critical controller of energy homeostasis. Thus, canine genetics identified obesity genes and mechanisms relevant to both dogs and humans.
Malaria blood stage parasite development relies on glycolysis to generate ATP, which requires pyruvate to lactate conversion by an essential lactate dehydrogenase enzyme (LDH1). Conversely, parasites developing in the mosquito employ mitochondrial chemiosmosis for ATP production. The source of ATP during transition from vertebrate to insect is less clear; gametes form in the mosquito midgut lumen within minutes of gametocyte ingestion, and while female gametes possess a mitochondrion, this organelle is absent from male gametes (microgametes). Here, we investigate a second LDH enzyme (LDH2) found exclusively in male gametocytes and microgametes. Knockout of Plasmodium berghei LDH2 expression reduces the number and size of exflagellation centres and radically diminishes oocyst development in Anopheles stephensi mosquitoes. Our data indicate that LDH2 supplements LDH1 activity to facilitate the cytokinesis step of male gametogenesis, while LDH1 alone is sufficient for motility of free-swimming microgametes. Our results point to a key role for glycolytic ATP production in microgamete formation and function and identify LDH activity as a potential malaria transmission-blocking drug target.
Obesity represents an escalating global health burden with profound medical and economic impacts. The conventional perspective on obesity revolves around its classification as a “pure” metabolic disorder, marked by an imbalance between calorie consumption and energy expenditure. Present knowledge, however, recognizes the intricate interaction of rare or frequent genetic factors that favor the development of obesity, together with the emergence of neurodevelopmental and mental abnormalities, phenotypes that are modulated by environmental factors such as lifestyle. Thirty years of human genetic research has unveiled >20 genes, causing severe early-onset monogenic obesity and ~1000 loci associated with common polygenic obesity, most of those expressed in the brain, depicting obesity as a neurological and mental condition. Therefore, obesity’s association with brain function should be better recognized. In this context, this review seeks to broaden the current perspective by elucidating the genetic determinants that contribute to both obesity and neurodevelopmental and mental dysfunctions. We conduct a detailed examination of recent genetic findings, correlating them with clinical and behavioral phenotypes associated with obesity. This includes how polygenic obesity, influenced by a myriad of genetic variants, impacts brain regions associated with addiction and reward, differentiating it from monogenic forms. The continuum between non-syndromic and syndromic monogenic obesity, with evidence from neurodevelopmental and cognitive assessments, is also addressed. Current therapeutic approaches that target these genetic mechanisms, yielding improved clinical outcomes and cognitive advantages, are discussed. To sum up, this review corroborates the genetic underpinnings of obesity, affirming its classification as a neurological disorder that may have broader implications for neurodevelopmental and mental conditions. It highlights the promising intersection of genetics, genomics, and neurobiology as a foundation for developing tailored medical approaches to treat obesity and its related neurological aspects.
Background: Adequate glucose supply is essential for brain function, therefore hypoglycemic states may lead to seizures. Since blood glucose supply for brain is buffered by liver glycogen, an impairment of liver glycogen synthesis by mutations in the liver glycogen synthase gene (GYS2) might result in a substantial neurological involvement. Here, we describe the phenotypes of affected siblings of two families harboring biallelic mutations in GYS2. Methods: Two suspected families - a multiplex Pakistani family (family A) with three affected siblings and a family of Moroccan origin (family B) with a single affected child who presented with seizures and reduced fasting blood glucose levels were genetically characterized. Whole exome sequencing (WES) was performed on the index patients, followed by Sanger sequencing-based segregation analyses on all available members of both families. Results: The variant prioritization of WES and later Sanger sequencing confirmed three mutations in the GYS2 gene (12p12.1) consistent with an autosomal recessive pattern of inheritance. A homozygous splice acceptor site variant (NM_021957.3, c. 1646 -2A>G) segregated in family A. Two novel compound heterozygous variants (NM_021957.3: c.343G>A; p.Val115Met and NM_021957.3: c.875A>T; p.Glu292Val) were detected in family B, suggesting glycogen storage disorder. A special diet designed to avoid hypoglycemia, in addition to change of the anti-seizure medication led to reduction in seizure frequency. Conclusions: This study suggests that the seizures in patients initially diagnosed with epilepsy might be directly caused, or influenced by hypoglycemia due to pathogenic variants in the GYS2 gene.
Plasmodium alveolins are cytoskeletal proteins with important roles in cell shape, tensile strength, and motility of mosquito-stage ookinetes and sporozoites. Two recent studies by Cepeda Diaz et al. and Liu et al. employ inducible knockdown of the essential blood-stage-expressed alveolin IMC1g to identify new roles in merozoite intracellular survival, schizogonic cell division, and male gametogenesis.
Plasmodium oocysts develop on the abluminal side of the mosquito midgut in relatively small numbers. Oocysts possess an extracellular cell wall—the capsule—to protect them from the insect's haemolymph environment. To further maximise transmission, each oocyst generates hundreds of sporozoites through an asexual multiplication step called sporogony. Completion of transmission requires sporozoite egress from the capsule (excystation), but this process remains poorly understood. In this study, we fused the parasite-encoded capsule protein Cap380 with green fluorescent protein in a transgenic P. berghei line, allowing live fluorescence imaging of capsules throughout sporogony and sporozoite excystation. The results show that capsules progressively weaken during sporulation ultimately resulting in sporozoite exit through small holes. Prior to formation of the holes, local thinning of the capsule was observed. Our findings support an excystation model based on local, rather than global, weakening of the capsule likely facilitated by local re-orientation of sporozoites and apical secretion.
The long-term clinical outcomes of severe obesity due to leptin signaling deficiency are unknown. We carry out a retrospective cross-sectional investigation of a large cohort of children with leptin (LEP), LEP receptor (LEPR), or melanocortin 4 receptor (MC4R) deficiency (n = 145) to evaluate the progression of the disease. The affected individuals undergo physical, clinical, and metabolic evaluations. We report a very high mortality in children with LEP (26%) or LEPR deficiency (9%), mainly due to severe pulmonary and gastrointestinal in-fections. In addition, 40% of surviving children with LEP or LEPR deficiency experience life-threatening ep-isodes of lung or gastrointestinal infections. Although precision drugs are currently available for LEP and LEPR deficiencies, as yet, they are not accessible in Pakistan. An appreciation of the severe impact of LEP or LEPR deficiency on morbidity and early mortality, educational attainment, and the attendant stigma-tization should spur efforts to deliver the available life-saving drugs to these children as a matter of urgency.
Malaria parasites carry out fatty acid synthesis (FAS) in their apicoplast organelle via a bacterially related (type II) enzymatic pathway. In the vertebrate host, exoerythrocytic Plasmodium stages rely on FAS, whereas intraerythrocytic stages depend on scavenging FA from their environment. In the mosquito, P. falciparum oocysts express and rely on FAS enzymes for sporozoite formation, but P. yoelii oocysts do not express, nor depend on, FAS enzymes and thus rely on FA scavenging to support sporogony. In P. berghei, FAS enzymes are similarly expendable for sporogony, indicating it conforms to the P. yoelii scenario. We show here that P. berghei, unexpectedly, expresses FAS enzymes throughout oocyst development. These findings indicate that P. berghei can employ FAS alongside FA scavenging to maximise sporogony and transmission, and is more similar to P. falciparum than previously assumed with respect to FA acquisition by the oocyst. The ability of oocysts to switch between FAS and scavenging could be an important factor in the non-competitive relationship of resource exploitation between Plasmodium parasites and their mosquito vectors, which shapes parasite virulence both in the insect and vertebrate.
Vitiligo is an autoimmune complex pigmentation disease characterized by non-pigmented patches on the surface of the skin that affect approximately 0.5–2% population worldwide. The exact etiology is still unknown; however, vitiligo is hypothesized to be a multifactorial and genetically heterogeneous condition. Therefore, the current study is designed to investigate the anthropometric presentation and genetic spectrum of vitiligo in fifteen consanguineous Pakistani families. The clinical evaluation of participating individuals revealed varying degrees of disease severity, with 23 years as the average age of disease onset. The majority of the affected individuals had non-segmental vitiligo (NSV). Whole exome sequencing analysis revealed clustering of rare variants of known vitiligo-associated genes. For instance, in the affected individuals of family VF-12, we identified three novel rare variants of PTPN22 (c.1108C>A), NRROS (c.197C>T) and HERC2 (c.10969G>A) genes. All three variants replaced evolutionarily conserved amino acid residues in encoded proteins, which are predicted to impact the ionic interactions in the secondary structure. Although various in silico algorithms predicted low effect sizes for these variants individually, the clustering of them in affected individuals increases the polygenic burden of risk alleles. To our knowledge, this is the first study that highlights the complex etiology of vitiligo and genetic heterogeneity in multiplex consanguineous Pakistani families.
Disruption of brain-expressed G protein-coupled receptor-10 (GPR10) causes obesity in animals. Here, we identify multiple rare variants in GPR10 in people with severe obesity and in normal weight controls. These variants impair ligand binding and G protein-dependent signalling in cells. Transgenic mice harbouring a loss of function GPR10 variant found in an individual with obesity, gain excessive weight due to decreased energy expenditure rather than increased food intake. This evidence supports a role for GPR10 in human energy homeostasis. Therapeutic targeting of GPR10 may represent an effective weight-loss strategy.
Membrane-located NAD(P) transhydrogenase (NTH) catalyses reversible hydride ion transfer between NAD(H) and NADP(H), simultaneously translocating a proton across the membrane. The enzyme is structurally conserved across prokaryotes and eukaryotes. In heterotrophic bacteria NTH proteins reside in the cytoplasmic membrane, whereas in animals they localise in the mitochondrial inner membrane. Eukaryotic NTH proteins exists in two distinct configurations (isoforms) and have non-mitochondrial functions in unicellular eukaryotes like Plasmodium, the causative agent of malaria. In this study, we carried out a systematic analysis of nth genes across eukaryotic life to determine its prevalence and distribution of isoforms. The results reveal that NTH is found across all major lineages, but that some organisms, notably plants, lack nth genes altogether. Isoform distribution and phylogenetic analysis reveals different nth gene loss scenarios in apicomplexan lineages, which sheds new light on the evolution of the Piroplasmida and Eimeriidae.
We previously demonstrated that 50% of children with obesity from consanguineous families from Pakistan carry pathogenic variants in known monogenic obesity genes. Here, we have discovered a novel monogenetic recessive form of severe childhood obesity using an in-house computational staged approach. The analysis included whole-exome sequencing data of 366 children with severe obesity, 1,000 individuals of the Pakistan Risk of Myocardial Infarction Study (PROMIS) study, and 200,000 participants of the UK Biobank to prioritize genes harboring rare homozygous variants with putative effect on human obesity. We identified five rare or novel homozygous missense mutations predicted deleterious in five consanguineous families in P4HTM encoding prolyl 4-hydroxylase transmembrane (P4H-TM). We further found two additional homozygous missense mutations in children with severe obesity of Indian and Moroccan origin. Molecular dynamics simulation suggested that these mutations destabilized the active conformation of the substrate binding domain. Most carriers also presented with hypotonia, cognitive impairment, and/or developmental delay. Three of the five probands died of pneumonia during the first 2 years of the follow-up. P4HTM deficiency is a novel form of syndromic obesity, affecting 1.5% of our children with obesity associated with high mortality. P4H-TM is a hypoxia-inducible factor that is necessary for survival and adaptation under oxygen deprivation, but the role of this pathway in energy homeostasis and obesity pathophysiology remains to be elucidated.
Autosomal-recessive cerebellar ataxias (ARCAs) are heterogeneous rare disorders mainly affecting the cerebellum and manifest as movement disorders in children and young adults. To date, ARCA causing mutations have been identified in nearly 100 genes; however, they account for less than 50% of all cases. We studied a multiplex, consanguineous Pakistani family presenting with a slowly progressive gait ataxia, body imbalance, and dysarthria. Cerebellar atrophy was identified by magnetic resonance imaging of brain. Using whole exome sequencing, a novel homozygous missense mutation ERCC8:c.176T>C (p.M59T) was identified that co-segregated with the disease. Previous studies have identified homozygous mutations in ERCC8 as causal for Cockayne Syndrome type A (CSA), a UV light-sensitive syndrome, and several ARCAs. ERCC8 plays critical roles in the nucleotide excision repair complex. The p.M59T, a substitution mutation, is located in a highly conserved WD1 beta-transducin repeat motif. In silico modeling showed that the structure of this protein is significantly affected by the p.M59T mutation, likely impairing complex formation and protein-protein interactions. In cultured cells, the p.M59T mutation significantly lowered protein stability compared to wildtype ERCC8 protein. These findings expand the role of ERCC8 mutations in ARCAs and indicate that ERCC8-related mutations should be considered in the differential diagnosis of ARCAs.
Recent advances in genetic analysis have significantly helped in progressively attenuating the heritability gap of obesity and have brought into focus monogenic variants that disrupt the melanocortin signalling. In a previous study, next generation sequencing has revealed a monogenic aetiology in ~50% of the children with severe obesity from a consanguineous population in Pakistan. Here we assess rare variants in obesity causing genes in young adults with severe obesity from the same region. Genomic DNA from randomly selected 128 young adult obese subjects (BMI=37.2 ± 0.3; age=18.4 ± 0.3 years) was screened by conventional or augmented whole exome analysis for point mutations and copy number variants (CNVs). Leptin, insulin and cortisol levels were measured by ELISA. We identified thirteen subjects carrying 13 different pathogenic or likely pathogenic variants in LEPR, PCSK1, MC4R, NTRK2, POMC, SH2B1 and SIM1. We also identified for the first time in the human, two homozygous stop-gain mutations in ASNSD1 and IFI16 genes. Inactivation of these genes in mouse models has been shown to result in obesity. Additionally, we describe 9 homozygous mutations (7 missense, 1 stop-gain and 1 stop-loss) and 4 copy-loss CNVs in genes or genomic regions previously linked to obesity-associated traits by genome-wide association studies (GWAS). Unexpectedly, in contrast to obese children, pathogenic mutations in LEP and LEPR were either absent or rare, in this cohort of young adults. High morbidity and mortality risks and social disadvantage of children with LEP or LEPR deficiency may in part explain this difference between the two cohorts.
Objective. TB recurrence is the second episode of TB after initial treatment bringing about an additional 7% load in TB burden intensified by 17.7% of multidrug-resistant recurrent cases. It is necessary to curb recurrence so that attempts to deal with active disease can be made more effective. This study aimed to characterize sociodemographic and clinical factors associated with recurrent TB in a high-burden setting. Methodology. A retrospective case-control study was carried out at two hospitals in Rawalpindi, Pakistan. TB patients and controls were included in the study. Sociodemographic and clinical data were collected by questionnaire from all subjects. Multivariate regression analysis was performed to determine factors associated with TB and TB recurrence respectively. Results. In our study cohort, factors significantly associated with TB were low BMI (OR: 0.961 (CI 0.954–0.968), p<0.001), female gender (OR: 2.065 (CI 1.922–2.219), p<0.001), being single/unmarried (OR: 1.214 (CI 1.109–1.328), p=0.003), middle-income status (OR: 1.935 (CI 1.616–2.323), p<0.001), smoking (OR: 1.567 (CI 1.435–1.710), p<0.001), and diabetes mellitus (OR: 1.142 (CI 1.017–1.278), p=0.023). TB recurrence constituted 11.2% of patients presenting to the hospital. Compared with the first episode of TB, cases with recurrence were more likely to be older (OR: 1.011 (CI 1.004–1.017), p<0.001), have disease awareness (OR: 1.906 (CI 1.486–2.437), p<0.001), smear positive (OR: 2.384 (CI 1.650–3.536), p<0.001), and be drug-resistant (OR: 5.615 (CI 4.265–7.386), p<0.001). Conclusion. In the present study cohort, low BMI, female gender, being single, middle-income status, being unemployed, smoking, and being diabetic came out to be the sociodemographic and clinical risk factors for TB. Further exploring the TB cases increasing age, drug resistance and smear positivity stood out to be the major sociodemographic and clinical factors of TB recurrence despite high disease awareness.