Biology subjects

Ahmed, A. R.

Publications and source records attributed to Ahmed, A. R..

4 recordsLinked to original sources

bioRxiv2026

Identification and functional assessment of GPCRs across human adipogenesis

Clinical obesity, defined as the presence of excess adiposity in conjunction with the presence of at least one clinical presentation of disease, remains a significant social and economic burden. Pharmacological weight loss agents based on glucagon-like peptide-1 receptor (GLP-1R) targeting are effective but exhibit significant side-effects leading to cessation of treatment, weight regain and, importantly, re-development of co-morbidities. Adipose tissue, now established as a central mediator of energy balance, endocrine signalling and inflammation, plays a significant role in the protection against metabolic disease onset. Loss of adipose tissue expandability, insulin sensitivity and function is thought to be a pivotal event in the transition to clinical obesity. Targeting adipose tissue dysfunction prior to or following development of metabolic disease remains a key therapeutic strategy either in conjunction with incretin-based weight loss therapy, or as a stand-alone therapy. The recent confirmation of functional glucose-dependent insulinotropic polypeptide receptor (GIPR) in mature adipocytes has led to a significant shift in our mechanistic understanding of dual GLP-1R/GIPR agonists such as tirzepatide, with the addition of adipocyte-specific targeting thought to underpin its clinical superiority to GLP-1R agonism alone. However, the expression, regulation and mechanistic targets of GIPR, and indeed many G protein-coupled receptors (GPCRs), in human adipocytes remains unclear, with adipocyte development being particularly under-studied in this regard. Here we use unbiased transcriptomic analyses of human adipocyte development with high temporal resolution to identify the onset of human GPCR expression, uncovering a previously undocumented surge in expression following adipogenic induction and elegant gene waves throughout adipocyte development that may provide attractive pharmacological targets for adipose tissue dysfunction with or without weight loss. We functionally characterise GIPR, GLP-1 and CALCR/RAMP (Amylin) receptor activation at key differentiation timepoints, and identify a novel amylin response in early adipogenesis, presenting committed adipogenic precursors as a primary target of amylin signalling. HighlightsO_LIComprehensive transcriptomic analysis of human adipogenesis with improved temporal resolution and depth C_LIO_LIIdentification and classification of >150 GPCRs differentially regulated across adipocyte differentiation C_LIO_LIFunctional validation highlighting targeting of adipose stem cells and adipocytes using clinically approved receptor agonists C_LIO_LIGeneration of novel human adipocyte stem cell lines from healthy and obese individuals to drive early target validation and exploration of adipocyte biology with increased pre-clinical power. C_LI SummaryComprehensive temporal RNA sequencing across human adipocyte development with a focus on G-protein coupled receptor expression and activity.

cell biology↗

bioRxiv2025

Choosing the Best Route: Comparative Optimization of Wheat Transformation Methods for Improving Yield by Targeting TaARE1-D with CRISPR/Cas9

Wheat (Triticum aestivum L.) is one of the most important crops worldwide, supplying a major share of calories and protein for the global population. Incorporating gene editing into breeding programs is critical to improve yield and stress tolerance, yet wheat remains difficult to transform and regenerate efficiently. These bottlenecks limit the full application of CRISPR/Cas9 for improvement yield in wheat. To address this, transformation parameters were optimized for three methods: immature embryo transformation, callus transformation, and injection-based in planta transformation. Systematic optimization of Agrobacterium strain, bacterial density, acetosyringone concentration, and incubation conditions resulted in substantially improved transformation success. Efficiencies of 66.84% for immature embryos, 55.44% for callus, and 33.33% for in planta transformation were achieved, representing more than tenfold increase compared with previously reported rate of [~]3%. A key innovation was the shortening of the callus induction stage for immature embryos, reducing the time required for plant regeneration by approximately one month while maintaining high transformation efficiency. The protocols were validated through CRISPR/Cas9-mediated knockout of TaARE1-D, a negative regulator of nitrogen uptake and yield. Generated mutants exhibited increased grain number, spike length, grain length, and thousand-grain weight, as well as the characteristic stay-green phenotype associated with loss of TaARE1-D function. The optimized protocols provide robust platforms to accelerate gene-editing in wheat to increase yield and stress-tolerance.

plant biology↗

bioRxiv2024

A Cell Autonomous Free fatty acid receptor 4 - ChemR23 Signaling Cascade Protects Cardiac Myocytes from Ischemic Injury

Acute myocardial infarction (AMI) causes ischemic damage and cardiac remodeling that ultimately progresses into ischemic cardiomyopathy (ICM). Coronary revascularization reduces morbidity and mortality from an MI, however, reperfusion also induces oxidative stress that drives cardiac myocyte (CM) dysfunction and ICM. Oxidative stress in CMs leads to reactive oxygen species (ROS) production and mitochondrial damage. Free fatty acid receptor 4 (Ffar4) is a GPCR for long chain fatty acids (FA) that is expressed in multiple cell types including CMs. We have recently shown that CM-specific overexpression of Ffar4 protects the heart from systolic dysfunction in the context of ischemic injury. Mechanistically, in CMs, Ffar4 increases the levels of 18-hydroxyeicosapentaenoic acid (18-HEPE), an eicosapentaenoic acid (EPA)-derived, cardioprotective oxylipin (oxidatively modified FA). 18-HEPE is the precursor for resolvin E1 (RvE1), a cardioprotective, specialized pro-resolving mediator (SPM) that activates the GPCR ChemR23. We hypothesize Ffar4 in CMs protects the heart from oxidative stress and ischemic injury through activation of a CM-autonomous, Ffar4-ChemR23 cardioprotective signaling pathway. Here, we developed an in vitro hypoxia reoxygenation (H/R) model (3 hours of hypoxia, 17 hours of reoxygenation) in adult CMs as a model for ischemic injury. In adult CMs subjected to H/R, TUG-891, an Ffar4 agonist, attenuated ROS generation and TUG-891, 18-HEPE, and RvE1 protected CMs from H/R-induced cell death. More importantly, we found that the ChemR23 antagonist -NETA prevented TUG-891 cytoprotection in adult CMs subjected to H/R, demonstrating that ChemR23 is required for Ffar4 cardioprotection. In summary, our data demonstrate co-expression of Ffar4 and ChemR23 in the same CM, that Ffar4, 18-HEPE, and RvE1 attenuate H/R-induced CM death, and that ChemR23 is required for Ffar4 cardioprotection in H/R support a CM-autonomous Ffar4-ChemR23 cardioprotective signaling pathway.

physiology↗

bioRxiv2024

Loss of cped1 does not affect bone and lean mass in zebrafish

Human genetic studies have nominated Cadherin-like and PC-esterase Domain-containing 1 (CPED1) as a candidate target gene mediating bone mineral density (BMD) and fracture risk heritability. Recent efforts to define the role of CPED1 in bone in mouse and human models have revealed complex alternative splicing and inconsistent results arising from gene targeting, making its function in bone difficult to interpret. To better understand the role of CPED1 in adult bone mass and morphology, we conducted a comprehensive genetic and phenotypic analysis of cped1 in zebrafish, an emerging model for bone and mineral research. We analyzed two different cped1 mutant lines and performed deep phenotyping to characterize more than 200 measures of adult vertebral, craniofacial, and lean tissue morphology. We also examined alternative splicing of zebrafish cped1 and gene expression in various cell/tissue types. Our studies fail to support an essential role of cped1 in adult zebrafish bone. Specifically, homozygous mutants for both cped1 mutant alleles, which are expected to result in loss-of-function and impact all cped1 isoforms, exhibited no significant differences in the measures examined when compared to their respective wildtype controls, suggesting that cped1 does not significantly contribute to these traits. We identified sequence differences in critical residues of the catalytic triad between the zebrafish and mouse orthologs of CPED1, suggesting that differences in key residues, as well as distinct alternative splicing, could underlie different functions of CPED1 orthologs in the two species. Our studies fail to support a requirement of cped1 in zebrafish bone and lean tissue, adding to evidence that variants at 7q31.31 can act independently of CPED1 to influence BMD and fracture risk. Lay summaryBone mineral density (BMD) is a key indicator for predicting and diagnosing osteoporosis and fracture risk, and it has been estimated that up to 89% of variation in BMD is determined by genetics. Multiple human genetics studies have nominated CPED1 as a potential gene underlying BMD and fracture risk heritability, however the function of CPED1 remains poorly understood. In this study, we examined the role of cped1 in bone by quantifying over 200 morphological measures of vertebral and craniofacial bone size, shape, and density in two different mutant lines of zebrafish in which cped1 function was reduced or eliminated. We also examined lean tissue mass because co-heritability of this trait with BMD has also been hypothesized to involve CPED1. Surprisingly, despite the loss of cped1 function, there were no significant differences between the mutant zebrafish and their respective controls. Our study therefore fails to support a role for cped1 in bone and lean tissue, suggesting that hereditary influence on BMD and fracture risk can occur independently of CPED1.

genetics↗