Biology subjects

Klingenspor, M.

Publications and source records attributed to Klingenspor, M..

12 recordsLinked to original sources

bioRxiv2025

Endothelial deletion of ADGRF5 (GPR116) promotes fibro-inflammatory EndMT and impairs adaptive thermogenesis in brown adipose tissue

ObjectiveBrown adipose tissue (BAT) dissipates energy via non-shivering thermogenesis, and it is a promising therapeutic target for metabolic disease. While most research focuses on thermogenic adipocytes, emerging data point to critical contributions from the surrounding stromal niche. Here, we investigated the role of adhesion G protein-coupled receptors (aGPCRs) in BAT function, focusing on Adgrf5 (Gpr116), a receptor enriched in endothelial cells. MethodsWe used single-nuclei RNA sequencing to map aGPCRs expression across mouse and human BAT. We then examined the consequences of Adgrf5(Gpr116) loss using global, brown adipocyte, and endothelial-specific knockout mouse models under acute and prolonged cold exposure. ResultsInducible endothelial deletion of Adgrf5(Gpr116) impaired the maintenance of thermogenic capacity during prolonged--but not acute--cold exposure. This was not associated with defective angiogenesis, but rather with endothelial fibro-inflammatory reprogramming. Single-nuclei RNA sequencing analysis revealed endothelial-to- mesenchymal transition (EndMT) features, including induction of mesenchymal markers, collagens, and metalloproteinases, and loss of barrier genes. Adgrf5(Gpr116)-deficient endothelial cells also exhibited cytoskeletal remodeling and activation of stress fiber pathways, implicating Adgrf5(Gpr116) as a mechanosensory safeguard of endothelial identity. ConclusionEndothelial Adgrf5(Gpr116) preserves thermogenic competence in BAT by suppressing EndMT and maladaptive matrix remodeling. Our findings establish vascular mechanosensing as a critical determinant of thermogenic tissue homeostasis. HighlightsO_LIAdhesion GPCRs are the second most abundant GPCR family in mouse and human brown fat C_LIO_LIAdhesion GPCRs are enriched in non-adipocyte cell types in brown fat and participate in cell-cell contact signaling C_LIO_LIEndothelial Adgrf5(Gpr116) is required for thermogenic adaptation during prolonged cold exposure C_LIO_LILoss of Adgrf5(Gpr116) induces fibro-inflammatory reprogramming and endothelial-to-mesenchymal transition (EndMT) C_LI

molecular biology↗

bioRxiv2025

The Hypothalamic-Pituitary-Adrenal Axis Orchestrates Energy Homeostasis during Cold Exposure

Cold exposure stimulates the sympathetic nervous system (SNS) to activate brown fat thermogenesis and maintain optimal body temperature, while simultaneously triggering compensatory hyperphagia to restore energy balance. The mechanisms coordinating energy expenditure and intake, however, remain unclear. Here, we reveal that the hypothalamic-pituitary-adrenal (HPA) axis plays a dual role in this process: endogenous adrenocorticotropic hormone (ACTH) directly stimulates the melanocortin-2 receptor (MC2R) in brown adipocytes to promote thermogenesis, whereas glucocorticoids drive cold-induced hyperphagia and act permissively to enhance ACTH-mediated energy expenditure. These findings uncover previously unrecognized functions of the HPA axis and a delicate hormonal interplay that orchestrates energy homeostasis during cold stress. Targeting these pathways may offer novel strategies to mitigate hyperphagic responses associated with increased energy expenditure, with potential implications for obesity treatment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=184 HEIGHT=200 SRC="FIGDIR/small/677113v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1ac072forg.highwire.dtl.DTLVardef@10bc88corg.highwire.dtl.DTLVardef@9b9b5corg.highwire.dtl.DTLVardef@1f4e276_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThe HPA axis orchestrates cold adaptation. C_LIO_LIACTH activates brown fat thermogenesis in vitro and in vivo via activating MC2R. C_LIO_LIGlucocorticoids drive cold-induced hyperphagia. C_LIO_LIGlucocorticoids have a permissive effect on ACTH function in brown adipocytes. C_LI

physiology↗

bioRxiv2025

Single-cell metabolic imaging and digital scoring of fat tissue remodeling by label-free metabolic imaging

Adipose tissue plasticity and functional heterogeneity play a central role in maintaining energy homeostasis, and their malfunction leads to metabolic disorders such as obesity, diabetes, and cardiometabolic disease. Rapid, single-cell metabolic imaging of intact fat tissue not only extends our understanding of metabolic dynamics and heterogeneity but also holds great potential as a tool for clinical diagnosis. However, the use of exogenous labels and dyes in conventional optical microscopy results in tissue deformation and requires time-consuming tissue preparation. Here, we demonstrated single-cell imaging of metabolic changes and heterogeneity in freshly excised adipose tissues that can distinguish tissue types without the need for exogenous labels using bond-specific, non-destructive, mid-infrared optoacoustic microscopy (MiROM) that allows preserving the native tissue architecture with minimal sample preparation time. Further leveraging MiROM, we monitored intracellular molecular and morphological changes during postnatal remodeling of adipose tissue when metabolic characteristics of adipocytes undergo a transient drastic change. Additionally, we developed an AI-based quantitative spatial tissue analysis tool (Q-SAT) to predict the spatial distribution of white fat- and brown fat-like features, providing a robust digital scoring method for adipose tissue phenotypic assessment. Collectively, we implemented MiROM as an enabling technology to provide fast, label-free metabolic imaging of unprocessed adipose tissue, opening a new perspective for understanding and characterizing the morpho-functional dynamics of adipose tissue remodeling.

bioengineering↗

bioRxiv2025

Shiny-Calorie: A context-aware application for indirect calorimetry data analysis and visualization using R

Indirect calorimetry is a cornerstone technique for metabolic phenotyping of animal models in preclinical research, with well-established experimental protocols and platforms. However, a flexible, extensible, and user-friendly software suite that enables standardized integration of data and metadata from diverse metabolic phenotyping platforms--followed by unified statistical analysis and visualization--remains absent. We present Shiny-Calorie, an open-source interactive web application for transparent data and metadata integration, comprehensive statistical data analysis, and visualization of indirect calorimetry datasets. Shiny-Calorie is compatible with data formats from widely used commercial metabolic phenotyping platforms, such as TSE and Sable Systems, and includes functionality for exporting processed data in these formats. Built using GNU R and a Shiny-based reactive interface, Shiny-Calorie enables intuitive exploration of complex, multi-modal longitudinal datasets comprising categorical, continuous, ordinal, and count variables. The platform incorporates state-of-the-art statistical methods for robust hypothesis testing, thereby facilitating biologically meaningful interpretation of energy metabolism phenotypes, including resting metabolic rate and energy expenditure. Overall, Shiny-Calorie streamlines routine analysis workflows and enhances reproducibility and transparency in metabolic phenotyping studies.

bioinformatics↗

bioRxiv2025

In vitro model of human subcutaneous adipocyte spheroids for studying mitochondrial dysfunction and mitochondria activating compounds

Mitochondrial abnormalities drive subcutaneous white adipose tissue dysfunction in obesity, leading to metabolic complications. A key challenge in obesity research is the lack of in vitro models to study human adipocyte mitochondria. Here, we establish a human subcutaneous adipocyte spheroid model to characterize mitochondrial metabolism under obesity-relevant conditions and drug exposure. Human preadipocyte spheroids were differentiated in ultra-low attachment plates for 3 weeks in media free of thiazolidinediones. The differentiated adipocyte spheroids showed increased lipid accumulation, adipogenic gene expression, mitochondrial respiration and adiponectin secretion, and a proper response to hormonal stimulation. Lipid mixture administration during differentiation induced metabolic disturbances including mitochondrial respiration failure associated with increased mitochondrial biogenesis. Post-differentiation treatment with rosiglitazone, a peroxisome proliferator-activated receptor {gamma} agonist, improved mitochondrial bioenergetics and adiponectin secretion in lipid mixture-administered adipocyte spheroids. Our model enables precise measurement of adipocyte mitochondria under various conditions, providing a platform for mitochondria-related research and drug discovery in obesity.

molecular biology↗

bioRxiv2024

From Planning Stage To FAIR Data: A Practical Metadatasheet For Biomedical Scientists

Datasets consist of measurement data and metadata. Metadata provides context, essential for understanding and (re-)using data. Various metadata standards exist for different methods, systems and contexts. However, relevant information resides at differing stages across the data-lifecycle. Often, this information is defined and standardized only at publication stage, which can lead to data loss and workload increase. In this study, we developed Metadatasheet, a metadata standard based on interviews with members of two biomedical consortia and systematic screening of data repositories. It aligns with the data-lifecycle allowing synchronous metadata recording within Microsoft Excel, a widespread data recording software. Additionally, we provide an implementation, the Metadata Workbook, that offers user-friendly features like automation, dynamic adaption, metadata integrity checks, and export options for various metadata standards. By design and due to its extensive documentation, the proposed metadata standard simplifies recording and structuring of metadata for biomedical scientists, promoting practicality and convenience in data management. This framework can accelerate scientific progress by enhancing collaboration and knowledge transfer throughout the intermediate steps of data creation.

bioinformatics↗

bioRxiv2022

Secretin modulates appetite via brown adipose tissue - brain axis

Secretin activates brown adipose tissue (BAT) and induces satiation in both mice and humans. However, the exact brain mechanism of this satiety inducing, secretin-mediated gut-BAT-brain axis is unknown. In this placebo-controlled, single-blinded neuroimaging study, firstly using [18F]FDG-PET measures (n = 15), we established that secretin modulated brain glucose consumption through the BAT-brain axis. Predominantly, we found that BAT and caudate glucose uptake levels were negatively correlated (r = -0.54, p = 0.037) during secretin but not placebo condition. Then, using functional magnetic resonance imaging (fMRI; n = 14), we found that secretin down-regulated the brain response to appetizing food images and improved inhibitory control. Finally, in a PET-fMRI fusion analysis (n = 10), we disclosed the patterned correspondence between caudate glucose uptake and neuroactivity to reward and inhibition, showing that the secretin-induced neurometabolic coupling pattern promoted satiation. These findings suggest that secretin modulates the BAT-brain metabolic crosstalk and subsequent neurometabolic coupling to induce satiation, bearing potential clinical benefits for treating eating disorders. Significance of the studySecretin activates brown adipose tissue and induces satiation, but the underlying brain mechanisms are still unclear. This placebo-controlled PET-fMRI study uses brain metabolic and BOLD measures to dissect the modulatory effects of secretin on brain functions associative to satiation. Findings show that secretin i) modulates caudate glucose metabolism via the BAT-brain axis, ii) enhances BOLD response in inhibitory control, and iii) reduces reward-related BOLD response. Further evidence shows that these measured effects are tightly linked via the secretin-mediated brain neurometabolic coupling. This study significantly advances our knowledge on how secretin leads to satiation and highlights the potential role of secretin in treating eating disorders and obesity.

neuroscience↗

bioRxiv2022

Deep Phenotyping and Lifetime Trajectories Reveal Limited Effects of Longevity Regulators on the Aging Process in C57BL/6J Mice

Current concepts regarding the biology of aging are based on studies aimed at identifying factors regulating natural lifespan. However, lifespan as a sole proxy measure for aging can be of limited value because it may be restricted by specific sets of pathologies, rather than by general physiological decline. Here, we employed large-scale phenotyping to analyze hundreds of phenotypes and thousands of molecular markers across tissues and organ systems in a single study of aging male C57BL/6J mice. For each phenotype, we established lifetime profiles to determine when age-dependent phenotypic change is first detectable relative to the young adult baseline. We examined central genetic and environmental lifespan regulators (putative anti-aging interventions, PAAIs; the following PAAIs were examined: mTOR loss-of-function, loss-of-function in growth hormone signaling, dietary restriction) for a possible countering of the signs and symptoms of aging. Importantly, in our study design, we included young treated groups of animals, subjected to PAAIs prior to the onset of detectable age-dependent phenotypic change. In parallel to our studies in mice, we assessed genetic variants for their effects on age-sensitive phenotypes in humans. We observed that, surprisingly, many PAAI effects influenced phenotypes long before the onset of detectable age-dependent changes, rather than altering the rate at which these phenotypes developed with age. Accordingly, this subset of PAAI effects does not reflect a targeting of age-dependent phenotypic change. Overall, our findings suggest that comprehensive phenotyping, including the controls built in our study, is critical for the investigation of PAAIs as it facilitates the proper interpretation of the mechanistic mode by which PAAIs influence biological aging. HighlightsO_LIPhenotyping at scale defines lifetime trajectories of age-dependent changes in C57BL/6J mice C_LIO_LICentral genetic and environmental lifespan regulators (putative anti-aging interventions; PAAIs) influence age-sensitive phenotypes (ASPs) often long before the appearance of age-dependent changes in these ASPs C_LIO_LICorresponding genetic variants in humans also have age-independent effects C_LIO_LIMany PAAI effects shift the baseline of ASPs rather than slowing their rate of change C_LI

physiology↗

bioRxiv2021

Susceptibility to diet induced obesity at thermoneutral conditions is independent of UCP1

ObjectiveActivation of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) upon cold stimulation leads to substantial increase in energy expenditure to defend body temperature. Increases in energy expenditure after a high caloric food intake, termed diet-induced thermogenesis, are also attributed to BAT. These properties render BAT a potential target to combat diet-induced obesity. However, studies investigating the role of UCP1 to protect against diet-induced obesity are controversial and rely on the phenotyping of a single constitutive UCP1-knockout model. To address this issue, we generated a novel UCP1-knockout model by Cre-mediated deletion of Exon 2 in the UCP1 gene. We studied the effect of constitutive UCP1 knockout on metabolism and the development of diet-induced obesity. MethodsUCP1 knockout and wildtype mice were housed at 30{degrees}C and fed a control diet for 4-weeks followed by 8-weeks of high-fat diet. Body weight and food intake were monitored continuously over the course of the study and indirect calorimetry was used to determine energy expenditure during both feeding periods. ResultsBased on Western blot analysis, thermal imaging and noradrenaline test, we confirmed the lack of functional UCP1 in knockout mice. However, body weight gain, food intake and energy expenditure were not affected by deletion of UCP1 gene function during both feeding periods. ConclusionConclusively, we show that UCP1 does not protect against diet-induced obesity at thermoneutrality. Further we introduce a novel UCP1-KO mouse enabling the generation of conditional UCP1-knockout mice to scrutinize the contribution of UCP1 to energy metabolism in different cell types or life stages.

physiology↗

bioRxiv2020

Multicompartmental Non-invasive Sensing of Postprandial Lipemia in Humans with Multispectral Optoacoustic Tomography

Disturbed blood lipid profiles after food intake have been associated with increased risk for cardiovascular and metabolic disease. Postprandial lipid profiling (PLP) can be used as a risk factor for cardiovascular disease, insulin resistance and other metabolic diseases but is based today on frequent blood sampling over several hours after a meal, an approach that is invasive and inconvenient for patients. Non-invasive PLP may offer a favorable alternative for disseminated monitoring in humans. In this study, we investigate the use of localized lipid sensing guided by Multispectral Optoacoustic Tomography (MSOT) for non-invasive, label-free assessment of postprandial lipemia in human vasculature and in soft tissues. For penetrating deep in human tissue, we utilize measurements at 930 nm, where lipids exhibit strong light absorption in the near-infrared spectral range (NIR). In a pilot study, we longitudinally measured postprandial lipemia in healthy subjects over 6 hours following consumption of a high-fat meal. Localized measurements were obtained from four anatomical structures: the radial artery, the cephalic vein, the brachioradialis muscle and the subcutaneous fat of the forearm. Analysis of optoacoustic signals demonstrated a 63.4% mean lipid increase in intra-arterial lipids at approximately 4 hours postprandially, a 89.7% mean increase in intra-venous lipids at 3-hours, a 120.8% mean increase in intra-muscular lipids at 3-hours and a 30.5% mean increase in subcutaneous fat lipids at 4-hours. We discuss how portable MSOT offers unprecedented potential to study lipid metabolism that could lead to novel diagnostics and prevention strategies by offering label-free and non-invasive detection of tissue biomarkers implicated in cardiometabolic diseases.Competing Interest StatementV. Ntziachristos has stock/stock options in iThera Medical GmbH. All other authors have no competing interests to declare.View Full Text

bioengineering↗

bioRxiv2019

TIS7 and SKMc15 Regulate Adipocyte Differentiation and Intestinal Lipid Absorption

Delta-like homolog 1 (DLK1), an inhibitor of adipogenesis, controls the cell fate of adipocyte progenitors. Here we identify two independent regulatory mechanisms, transcriptional and translational, by which TIS7 (IFRD1) and its orthologue SKMc15 (IFRD2) regulate DLK1 levels. Mice deficient in both TIS7 and SKMc15 (dKO) had severely reduced adipose tissue and were resistant to high fat diet-induced obesity. Wnt signaling, a negative regulator of adipocyte differentiation was significantly up regulated in dKO mice. Elevated levels of the Wnt/{beta}-catenin target protein Dlk-1 inhibited the expression of adipogenesis regulators PPAR{gamma} and C/EBP, and fatty acid transporter CD36. Although both, TIS7 and SKMc15, contributed to this phenotype, they utilized two different mechanisms. TIS7 acted by controlling Wnt signaling and thereby transcriptional regulation of Dlk-1. On the other hand, here we provide distinctive experimental evidence that SKMc15 acts as a general translational inhibitor significantly affecting DLK-1 protein levels. Our study provides data describing novel mechanisms of DLK1 regulation in adipocyte differentiation involving TIS7 and SKMc15. SYNOPSIS O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=184 SRC="FIGDIR/small/719922v3_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@77d89corg.highwire.dtl.DTLVardef@2e0ad4org.highwire.dtl.DTLVardef@c923fdorg.highwire.dtl.DTLVardef@159d117_HPS_FORMAT_FIGEXP M_FIG C_FIG This study uncovered that IFRD1 (TIS7) and its orthologue IFRD2 (SKMc15) are two essential regulators of adipogenesis. These proteins are highly similar on the sequence level, yet they regulate adipocyte differentiation using different but complementary mechanisms. Our main findings are: O_LIIFRD1 (TIS7) and IFRD2 (SKMc15) knockout mice are resistant against diet-induced obesity C_LIO_LIIFRD1 (TIS7) and IFRD2 (SKMc15) are critical for proper nutritional fat uptake and adipogenesis C_LIO_LIIFRD1 (TIS7) controls adipogenesis via Wnt/{beta}-catenin-dependent transcriptional regulation of adipocyte-specific genes C_LIO_LIIFRD2 (SKMc15) regulates adipocyte-specific genes acting as a novel general translational inhibitor C_LI

cell biology↗

bioRxiv2019

A novel growth factor-dependent thermogenic brown adipocyte cell line from defined precursor cells

Molecular pathways regulating brown adipocyte formation and metabolism can be exploited as targets for the treatment of obesity and disorders of glucose and lipid metabolism such as type-2 diabetes. Investigations in this direction require adequate cell models for brown adipocytes and their precursors. We report the establishment of a novel clonal cell line derived from defined Lin-Sca1+ adipocyte precursors from murine interscapular brown fat. In contrast to most currently available lines, immortalization was achieved by serial passaging without viral or genetic manipulation. Instead, the media were supplemented with basic fibroblast growth factor, which was required for the maintenance of stable long-term growth and immature morphology. BATkl2 cells differentiated to adipocytes with high efficiency upon standard adipogenic induction independently of PPARg agonists and even at higher passage numbers. BATkl2 adipocytes showed readily detectable Uncoupling protein 1 (Ucp1) protein expression and acutely responded to norepinephrine with increased Ucp1 mRNA expression, lipolysis and uncoupled mitochondrial respiration. Highly efficient siRNA-mediated knockdown was demonstrated in the growth state as well as in differentiating adipocytes, whereas plasmid DNA transfection was achieved in immature cells. These features make the BATkl2 cell line an attractive brown (pre)-adipocyte cell model.

cell biology↗