Biology subjects

Sangaraju, D.

Publications and source records attributed to Sangaraju, D..

4 recordsLinked to original sources

bioRxiv2026

Hypothalamic oligodendrocytes regulate systemic energy balance through Notch-dependent state transitions

The central mechanisms through which glial cells regulate whole-body metabolism remain poorly understood. Here, we identify Notch signaling in hypothalamic oligodendrocyte lineage cells as a previously unrecognized regulator of systemic energy homeostasis. Pharmacological inhibition of the Notch ligands Jagged1 (Jag1) and Jagged2 (Jag2) induces rapid and reversible weight loss across diverse physiological and metabolic contexts independently of toxicity or caloric intake. Single-nucleus transcriptomic analyses identify hypothalamic oligodendrocyte precursor cells (OPCs) as the principal Notch-responsive population following systemic Jag1/2 inhibition and reveal expansion of a metabolically specialized GPR17 intermediate state characterized by enhanced oxidative metabolism and increased predicted communication with hypothalamic neurons. This glial remodeling is accompanied by fasting-like transcriptional reprogramming of AgRP neurons, reorganization of melanocortin-autonomic circuit activity, and activation of peripheral catabolic programs. Importantly, selective deletion of Notch1/2 in hypothalamic OPCs recapitulates the major physiological and metabolic effects of systemic Jag1/2 inhibition, establishing oligodendrocyte Notch signaling as a causal regulator of whole-body metabolism. Together, our findings establish Notch-dependent oligodendrocyte state transitions as a previously unrecognized mechanism linking glial plasticity to systemic energy homeostasis.

physiology↗

bioRxiv2025

The Secreted Metabolite Isopentenyladenine from Faecalibacterium prausnitzii Mitigates Gut Inflammation

Colonic microbiome dysbiosis is correlated with inflammatory bowel disease (IBD), and depletion of the commensal bacterium Faecalibacterium prausnitzii (F. prausnitzii) is routinely observed in the metagenomic analyses of IBD patient microbiome samples. F. prausnitzii is likely beneficial to hosts, as oral administration of F. prausnitzii strain A2-165 has anti-inflammatory properties in murine models of colitis. Previous studies attribute the anti-inflammatory effects of F. prausnitzii A2-165 to production of the short-chain fatty acid butyrate, as well as a 15 kDa protein known as microbial anti-inflammatory molecule (MAM). Here, we verified that oral dosing of strain A2-165 protects against DSS-induced murine colitis and further show the aqueous-soluble secreted fraction of overnight cultures from a collection of F. prausnitzii strain inhibit inflammatory signatures, including the activation of the hosts NF-{kappa}B pathway, production of IL-8, and differentiation of naive T cells into the TH17 lineage. We find that MAM is secreted in extracellular vesicles; however, MAM-containing vesicles do not have anti-inflammatory properties in our collection of assays and suggests that MAM is likely not a direct contributor. Untargeted and targeted mass spectrometry metabolomics analyses on the soluble anti-inflammatory secretome yielded several unique F. prausnitzii metabolites, including isopentenyladenine. We demonstrated isopentenyladenine independently modulates host cellular signaling and immune responses and suggests this newly identified metabolite with human immunomodulatory properties may be useful towards the discovery of IBD-focused therapeutics.

microbiology↗

bioRxiv2023

Nicotinic acetylcholine receptor signaling maintains epithelial barrier integrity

Disruption of epithelial barriers is a common disease manifestation in chronic degenerative diseases of the airways, lung and intestine. Extensive human genetic studies have identified risk loci in such diseases, including in chronic obstructive pulmonary disease (COPD) and inflammatory bowel diseases (IBD). The genes associated with these loci have not fully been determined, and functional characterization of such genes requires extensive studies in model organisms. Here, we report the results of a screen in Drosophila melanogaster that allowed for rapid identification, validation and prioritization of COPD risk genes that were selected based on risk loci identified in human genome-wide association studies (GWAS) studies. Using intestinal barrier dysfunction in flies as a readout, our results validate the impact of candidate gene perturbations on epithelial barrier function in 56% of the cases, resulting in a prioritized target gene list. We further report the functional characterization in flies of one family of these genes, encoding for nicotinic acetylcholine receptor subunits (nAchR). We find that nAchR signaling in enterocytes of the fly gut promotes epithelial barrier function and epithelial homeostasis by regulating the production of the peritrophic matrix. Our findings identify COPD associated genes critical for epithelial barrier maintenance, and provide insight into the role of epithelial nAchR signaling for homeostasis.

genetics↗

bioRxiv2022

Discovery of thyrocyte heterogeneity reveals an essential role of Notch signaling in thyroid function and mammalian homeostasis

The thyroid functions at the apex of a web of endocrine organs that control cell growth, differentiation and metabolic homeostasis. Thyroid dysregulation significantly impacts human health in myriad ways with thyroid diseases standing as the most common endocrine disorder. Despite the essential role of the thyroid in human health, a high-resolution view of the cellular composition as well as molecular mechanisms that govern function of this crucial organ have been lacking. Employing the first single-cell analyses of adult mouse thyroid, we here report the discovery of unexpected thyrocyte heterogeneity, specifically three distinct thyrocyte subtypes marked by different metabolic and Notch signaling patterns. Using a battery of pharmacologic and genetic methods, we find that selective inhibition of Notch ligands and receptors disrupts thyrocyte mitochondrial activity and ROS production, thus decreasing levels of circulating thyroid hormones, inducing hypothyroidism and disrupting whole-body thermoregulation. We find an enriched frequency of hypothyroidism in children with Alagille Syndrome, a genetic disorder marked by Notch loss-of-function mutations, suggesting that our Notch-thyroid mechanisms are relevant in humans and directly account for Alagille hypothyroidism. Overall, our work reveals that Notch, although classically described as a developmental pathway that determines cell fate, controls homeostasis and thermoregulation in the adult through a mitochondria-based mechanism in a subset of thyrocytes. Our fine-grained picture of the thyroid unveils a novel understanding of this key metabolic organ and provides clinically impactful insights into its pathological dysfunctions.

cell biology↗