Biology subjects

Georgiadi, A.

Publications and source records attributed to Georgiadi, A..

4 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

From Brown to White: Brown Adipose Tissue Endothelial Cells whiten in Culture Conditions

Endothelial cells (ECs) are central regulators of vascular and metabolic homeostasis, yet their organ- and depot-specific diversity remains underexplored. Two major types of adipose tissue (AT) can be distinguished that differ substantially in their physiological function and vascularization: white AT (WAT), which is the major energy storage and brown AT (BAT), which is highly vascularized and dissipates energy [1-5]. While ECs from these depots likely contribute to adipose function, their characterization has been hindered by technical limitations in isolation and culture. Here, we establish a protocol for isolating and expanding ECs from murine BAT and WAT, enabling transcriptomic and functional analyses across depots. We demonstrate that freshly isolated BAT-ECs express depot-specific gene signatures, including Rgcc, Cdkn1c, Tcf15, Meox2, and Efnb1, several of which are dynamically regulated during cold-induced BAT activation. These findings reveal novel BAT-EC markers and highlight specialized endothelial programs that may support thermogenesis. However, we also uncover that culturing BAT-ECs profoundly remodels EC identity. Transcriptomic profiling shows that BAT-ECs rapidly downregulate BAT-specific markers and acquire features resembling WAT- and lymphatic ECs. This dedifferentiation is accompanied by signatures of proliferation, adhesion remodeling, and endothelial-to-mesenchymal transition. While these changes present challenges for maintaining depot-specific identity in culture, they also provide a framework to better interpret experimental outcomes and to investigate EC plasticity. Taken together, our study delivers a novel isolation and culture protocol for adipose ECs, defines BAT-EC markers, and demonstrates how culture conditions reshape their identity. These insights build the foundation for future research of AT vasculature. HighlightsO_LIFast method to purify endothelial cells (ECs) for direct RNA or protein extraction. C_LIO_LIEasy method to isolate and culture ECs specifically from thermogenic adipose tissue. C_LIO_LINovel signature of BAT-ECs regulated upon browning and lost in culture. C_LIO_LIRGC-32, p57kip2, TCF15/MEOX2 and EFNB1 as novel BAT-EC-specific markers. C_LI

cell biology↗

bioRxiv2022

Fasting-sensitive SUMO-switch on Prox1 controls hepatic cholesterol metabolism

The liver is the major metabolic hub, ensuring appropriate nutrient supply during fasting and feeding. In obesity, accumulation of excess nutrients hampers proper liver function and is linked to non-alcoholic fatty liver disease. Understanding the signaling mechanisms that enable hepatocytes to quickly adapt to dietary cues, might help to restore balance in liver diseases. Post-translational modification by attachment of the Small Ubiquitin-like Modifier (SUMO), allows for a dynamic regulation of numerous processes including transcriptional reprograming. Here, we demonstrate that the specific SUMOylation of transcription factor Prox1 represents a nutrient-sensitive determinant of hepatic fasting metabolism. Prox1 was highly modified by SUMOylation on lysine 556 in the liver of ad libitum and re-fed mice, while this modification was strongly abolished upon fasting. In a context of diet-induced obesity, Prox1 SUMOylation became insensitive to fasting cues. Hepatocyte-selective knock in of a SUMOylation-deficient Prox1 mutant into mice fed a high fat/high fructose diet led to reduction of systemic cholesterol levels, associated with the induction of bile acid detoxifying pathways in mutant livers during fasting. As appropriate and controlled fasting protocols have been shown to exert beneficial effects on human health, tools to maintain the nutrient-sensitive SUMOylation switch on Prox1 may thus contribute to the development of "fasting-based" approaches for the maintenance of metabolic health.

physiology↗

bioRxiv2019

HILPDA uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation

Obesity promotes accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid accumulation in the development of obesity-induced adipose tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency in bone marrow-derived macrophages markedly reduced intracellular lipid levels and accumulation of fluorescently-labeled fatty acids in lipid droplets. Decreased lipid storage in HILPDA-deficient macrophages could be almost completely rescued by inhibition of adipose triglyceride lipase (ATGL) and was associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency did not alter inflammatory or metabolic parameters, despite markedly reducing lipid storage in adipose tissue macrophages. Our data indicate that HILPDA is a lipid-induced physiological inhibitor of ATGL-mediated lipolysis that uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Overall, our data question the importance of lipid storage in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.

physiology↗