Biology subjects

Kornfeld, J.-W.

Publications and source records attributed to Kornfeld, J.-W..

8 recordsLinked to original sources

bioRxiv2025

EctoShed: A novel Gene Delivery Platform for Functional Analysis of Adipocyte-Shed Proteoforms

ObjectiveThe proteolytic cleavage of membrane-bound proteins, ectodomain shedding, functionally expands the reservoire of proteins/peptides available for endocrine crosstalk, and metabolic regulation. However, the functional understanding of secreted proteoforms, including whether they act synergistically or antagonistically with their membrane precursors, is often unknown. We aimed to develop a novel viral vector based gene delivery platform enabling characterization of both membrane-bound and soluble proteoforms in adipocytes, independent of endogenous shedding. ResultsWe describe a novel platform, termed EctoShed, achieves expression of proteoforms of amine oxidase copper-containing 3 (AOC3) in adipocytes by capitalising on both the established lentiviral (LV) and AAV gene delivery systems, expressing full length or a soluble AOC3 mimic (m-sAOC3) isoforms. In vitro transduction of primary white adipocytes induced significant expression of both isoforms, retaining AOC3 enzymatic activity. In vivo delivery to inguinal white adipose tissue enabled depot-specific AOC3 expression and increased abundance of m-sAOC3 in the serum. Mice expressing m-sAOC3 exhibited reduced fat mass and fasting glucose levels. ConclusionEctoShed represents a versatile tool to dissect the functional roles of soluble proteoforms shed from adipocytes, enabling in vitro and in vivo applications in cardiometabolic health and disease.

molecular biology↗

bioRxiv2025

Dietary sulfur amino acid restriction elicits a cold-like transcriptional response in inguinal but not epididymal white adipose tissue of male mice

IntroductionAbout 1 billion people are living with obesity worldwide. GLP-1-based drugs have massively transformed care, but long-term consequences are unclear in part due to reductions in energy expenditure with ongoing use. Diet-induced thermogenesis (DIT) and cold exposure (CE) raise EE via brown adipose tissue (BAT) activation and beiging of white adipose tissue (WAT). Methionine restriction (MetR) is a candidate DIT stimulus, but its EE effect has not been benchmarked against CE, nor have their tissue-level interactions been defined. Objective & MethodsIn a 2x2 design (Control vs. MetR; room temperature, RT: 22 {degrees}C vs. CE: 4 {degrees}C for 24 h), we used male C57BL/6N mice to benchmark MetR-induced thermogenesis against CE and mapped how diet and temperature interact across tissues. Bulk RNA-seq profiled liver, iBAT, iWAT, and eWAT. Differential expression was modeled with main effects and a dietxtemperature interaction. KEGG GSEA was used to assess pathway-level enrichment. ResultsMetR increased EE at RT and shifted fuel use towards lipid oxidation, supporting MetR as a bona fide DIT stimulus. CE elevated EE across diets and blunted diet differences. Transcriptomic responses were tissue-specific: in liver, CE dominated gene induction while MetR and CE cooperatively repressed genes. The combination enriched glucagon/AMPK-linked and core metabolic pathways. In iBAT, CE dominated thermogenic and lipid-oxidation programs with minimal MetR contribution. In iWAT, MetR and CE acted largely additively with high concordance, enhancing fatty-acid degradation, PPAR signaling, thermogenesis, and TCA cycle pathways. In eWAT, robust co-dependent and synergistic differential expression emerged only with MetR+CE. ConclusionMetR is a genuine DIT stimulus that remodels metabolism in a tissue-specific manner. Our study provides a tissue-resolved transcriptomic resource that benchmarks diet-induced (MetR) against cold-induced thermogenesis and maps their interactions across liver, iBAT, iWAT, and eWAT.

molecular biology↗

bioRxiv2025

Acyl-CoA Binding Protein is Dispensable for White and Brown Adipose Tissue Function

Acyl-CoA binding protein (ACBP) plays a vital role in lipid metabolism by mediating the intracellular flux and utilization of long-chain acyl-CoAs. In this study we generated brown- and white adipose tissue specific knockout mice (Adipoq-Acbp-/-) and brown adipose tissue specific knockout mice (Ucp1-Acbp-/-) to investigate the role of ACBP in adipose tissue function. Here we demonstrate that loss of ACBP does not affect body weight, fat and lean mass, food intake and systemic energy expenditure, even under cold stress. Transcriptomic data show only minor changes in gene expression, whereas lipidomic profiling reveals a subtle increase in acyl-carnitines levels in brown adipose tissue. However, lipolytic activity in white adipose tissue as well as plasma glycerol, non-esterified fatty acid and triacylglycerol levels remained unaffected. In addition, no changes in mitochondrial respiration in BAT were observed. Taken together, our findings suggest that ACBP is dispensable for adipose tissue function and systemic energy metabolism, including thermoregulation.

biochemistry↗

bioRxiv2024

A multi-omics census reveals obesity-associated microRNA miR-let-7 as novel instigator of adipose mitochondrial dysfunction and of intergenerational metabolic decline.

We here describe that obesity and weight loss in male mice cause reversible abnormalities in glucose and lipid metabolism, serum metabolomes and lipidomes as well as expression of microRNAs, mRNAs and proteins controlling mitochondrial function in epididymal white adipose tissue. When mating obese male mice with lean females, we observed reductions in expression and translation of genes encoding mitochondrial respiratory components in (F1) offspring that closely resemble those observed in the paternal (F0) generation. When mapping miRNA regulation across somatic organs (i.e., liver, adipose) and sperm and F0/1 generations, we found that obesity and weight loss reversibly affected miRNA levels, and that let-7 isoforms were induced in obese F0 and F1 adipose tissue and sperm of obese F0 mice, eliciting qualitatively similar responses in two adjacent tissues. Overexpressing let-7 in adipocytes silenced DICER1, a miRNA processing enzyme crucial for adipose adaptation to obesity as evidenced by deficiencies in mitochondrial function following DICER1 loss in primary adipocytes. Also, microinjection of synthetic let-7 mimetics at physiological levels found in obese sperm into zygotes from lean mice elicited glucose intolerance and impediments in adipose mitochondrial gene expression in mice sired from let-7 microinjected zygotes, phenocopying hereditary aspects of paternal obesity. When performing single-cell RNA-Seq of miRNA-injected embryos, let-7 impaired mitochondrial gene expression, suggesting altered oxidative metabolism following zygotic let-7 delivery. When studying miRNA alterations in human semen, lifestyle-induced weight loss downregulated hsa-let-7, suggesting similar roles for human let-7 in gametic epigenomes and embryogenesis.

physiology↗

bioRxiv2022

Nanopore sequencing unveils the complexity of the cold-activated murine brown adipose tissue transcriptome

1.Alternative transcription increases transcriptome complexity by expression of multiple transcripts per gene and thus fine tunes cellular identity and function. Annotation and quantification of transcripts at complex loci using short-read sequencing is non-trivial. Recent long-read sequencing methods such as those from Oxford Nanopore Technologies (ONT) and Pacific Biosciences aim at overcoming these problems by sequencing full length transcripts. Activation of BAT thermogenesis involves major transcriptomic remodelling and positively affects metabolism via increased energy expenditure and endocrine factors. Here we comprehensively benchmark features of ONT long-read sequencing protocols compared to Illumina shortread sequencing assessing alignment characteristics, gene and transcript detection and quantification, differential gene and transcript expression, transcriptome reannotation and differential transcript usage (DTU). We find that ONT sequencing is superior to Illumina for transcriptome reassembly and reduces the risk of false-positive events due to the ability to unambiguously map reads to transcripts, at the expense of statistical power for calling differentially expressed features. We identified novel isoforms of genes undergoing DTU in cold-activated BAT including Cars2, Adtrp, Acsl5, Scp2, Aldoa and Pde4d, validated by RT-qPCR. Finally, we provide a reannotation of the murine iBAT transcriptome as a valuable resource for researchers interested in the molecular biology underlying the regulation of BAT.

molecular biology↗

bioRxiv2022

Cold-induced expression of a truncated Adenylyl Cyclase 3 acts as rheostat to brown fat function.

Promoting brown adipose tissue (BAT) activity has been recognized as innovative therapeutic approach to improve obesity and metabolic disease. Whilst the molecular circuitry underlying thermogenic activation of BAT is well understood, the processes underlying rheostatic regulation of BAT to maintain homeostasis and avoid excessive energy dissipation remain ill-defined. Increasing cyclic AMP (cAMP) biosynthesis is key for BAT activation. Here, we demonstrate that ADCY3, an adenylyl cyclase whose expression is induced during cold exposure and regulates cAMP homeostasis in thermogenic fat, is dispensable for BAT function in lean mice, but becomes critical during obesity. Furthermore, by combining RNA-seq with epigenomic H3K4me3 profiling, we detected a novel, cold-inducible promoter that generates a 5 truncated Adcy3-at mRNA isoform, Adcy3-at. Mice lacking only Adcy3-at, but not full-length Adcy3, displayed increased energy expenditure already under lean conditions and were protected against obesity and ensuing metabolic imbalances. Subcellularly, translated ADCY3-AT proteins are retained in the endoplasmic reticulum (ER), did not translocate to the cell membrane, and lacked enzymatic activity. By interacting with ADCY3, ADCY3-AT retained ADCY3 in the ER and, thereby, reduced the plasma membrane pool of ADCYs available for G-protein mediated cAMP synthesis. Thereby, ADCY3-AT acts as a signaling rheostat in BAT, limiting adverse consequences of uncurbed cAMP activity after long-term BAT activation. Adcy3-at induction was driven by a cold-induced, truncated isoform of the transcriptional cofactor PPARGC1A (PPARG Coactivator 1 Alpha, PPARGC1A-AT). Expression of Ppargc1a-at and Adcy3-at are evolutionary conserved, indicating that transcriptional rewiring by commissioning of alternative promoters is key for thermogenic fat function.

cell biology↗

bioRxiv2021

Comprehensive transcriptional profiling and mouse phenotyping reveals dispensable role for adipose tissue selective long noncoding RNA Gm15551

1Cold and nutrient activated brown adipose tissue (BAT) is capable of increasing systemic energy expenditure via uncoupled respiration and secretion of endocrine factors thereby protecting mice against diet-induced obesity and improving insulin response and glucose tolerance in men. Long non-coding RNAs (lncRNAs) have recently been identified as fine tuning regulators of cellular function. While certain lncRNAs have been functionally characterised in adipose tissue, their overall contribution in the activation of BAT remains elusive. We identified lncRNAs correlating to inter-scapular brown adipose tissue (iBAT) function in high fat diet (HFD) and cold stressed mice. We focused on Gm15551 which has an adipose tissue specific expression profile, is highly upregulated during adipogenesis and downregulated by {beta}-adrenergic activation in mature adipocytes. Albeit we performed comprehensive transcriptional and adipocyte physiology profiling in vitro and in vivo, we could not detect an effect of gain or loss of function of Gm15551.

molecular biology↗

bioRxiv2019

Senescence-associated metabolomic phenotype in primary and iPSC-derived mesenchymal stromal cells

Long-term culture of primary cells is reflected by functional and secretory changes, which ultimately result in replicative senescence. In contrast, induced pluripotent stem cells (iPSCs) do not reveal any signs of cellular aging while in the pluripotency state, whereas little is known how they senesce upon differentiation. Furthermore, it is largely unclear how the metabolome of cells changes during replicative senescence and if such changes are consistent across different cell types. In this study, we have directly compared culture expansion of primary mesenchymal stromal cells (MSCs) and iPSC-derived MSCs (iMSCs) until they reached growth arrest after a mean of 21 and 17 cumulative population doublings, respectively. Both cell types acquired similar changes in morphology, in vitro differentiation potential, up-regulation of senescence-associated beta-galactosidase, and senescence-associated DNA methylation changes. Furthermore, MSCs and iMSCs revealed overlapping gene expression changes during culture expansion, particularly in functional categories related to metabolic processes. We subsequently compared the metabolome of MSCs and iMSCs at early and senescent passages and observed various significant and overlapping senescence-associated changes in both cell types, including down-regulation of nicotinamide ribonucleotide and up-regulation of orotic acid. Replicative senescence of both cell types was consistently reflected by the metabolic switch from oxidative to glycolytic pathways. Taken together, long-term culture of iPSC-derived MSCs evokes very similar molecular and functional changes as observed in primary MSCs. Replicative senescence is associated with a highly reproducible senescence-associated metabolomics phenotype, which may be used to monitor the state of cellular aging.

cell biology↗