Biology subjects

Guertin, D.

Publications and source records attributed to Guertin, D..

4 recordsLinked to original sources

bioRxiv2025

Rlim coordinates diurnal regulation of food intake and thermogenesis

Energy homeostasis in mice is maintained through coordinated activity among hypothalamic nuclei that regulate food intake and thermogenesis. These processes must adapt to the sleep-wake cycle, yet the underlying pathways, cell types, and molecular mechanisms governing their diurnal regulation remain poorly understood. We show that mice lacking the E3 ubiquitin ligase Rlim are lean and resistant to diet-induced obesity, owing to reduced food intake and enhanced brown adipose tissue (BAT) thermogenesis. We identify GABAergic neurons in the suprachiasmatic nucleus (SCN)--components of the central circadian clock--as mediators of these effects. Specifically, Rlim in RIP-Cre+ neurons governs daily thermogenic rhythms, while Rlim in vasoactive intestinal peptide (VIP)-expressing neurons modulates diurnal feeding behavior. Thus, Rlim is a key regulator of diurnal rhythms controlling energy balance.

physiology↗

bioRxiv2025

Pancreatic cancer cachexia is mediated by PTHrP-driven disruption of adipose de novo lipogenesis

Pancreatic cancer patients have the highest rates and most severe forms of cancer cachexia, yet cachexia etiologies remain largely elusive, leading to a lack of effective intervening therapies. Parathyroid hormone-related protein (PTHrP) has been clinically implicated as a putative regulator of cachexia, with serum PTHrP levels correlating with increased weight loss in PDAC patients. Here we show that cachectic PDAC patients have high expression of tumor PTHrP and use a genetically engineered mouse model to functionally demonstrate that loss of PTHrP blocks cachectic wasting, dramatically extending overall survival. The re-expression of PTHrP in lowly cachectic models is sufficient to induce wasting and reduce survival in mice, which is reversed by the conditional deletion of the PTHrP receptor, Pth1r, in adipocytes. Mechanistically, tumor-derived PTHrP suppresses de novo lipogenesis in adipocytes, leading to a molecular rewiring of adipose depots to promote wasting in the cachectic state. Finally, the pharmacological disruption of the PTHrP-PTH1R signaling axis abrogates wasting, highlighting that a targeted disruption of tumor-adipose crosstalk is an effective means to limit cachexia. STATEMENT OF SIGNIFICANCEPancreatic ductal adenocarcinoma (PDAC) is the prototypical cancer type associated with cancer cachexia, a debilitating wasting syndrome marked by adipose tissue loss and muscle atrophy. Herein, we establish that PTHrP is a tumor-derived factor that facilitates cachexia by downregulating de novo lipogenesis in adipocytes and that blocking PTHrP is an effective means to limit wasting in preclinical mouse models.

cancer biology↗

bioRxiv2024

An aneuploidy epistasis map reveals metabolic vulnerabilities associated with supernumerary chromosomes in cancer

Despite the general detriment of aneuploidy to cellular fitness, >90% of solid tumors carry an imbalanced karyotype. Regardless of this existing paradox, our understanding of the molecular responses to aneuploidy remains limited. Here, we explore these cellular stresses and unique vulnerabilities in aneuploid human mammary epithelial cells (HMECs) enriched for breast cancer-associated copy number alterations (CNAs). To uncover the genetic dependencies specific to aneuploid cells, we conducted a comprehensive, genome-wide CRISPR knockout screen targeting isogenic diploid and aneuploid HMEC lines. Our study reveals that aneuploid HMECs exhibit an increased reliance on pyrimidine biosynthesis and mitochondrial oxidative phosphorylation genes, and demonstrate heightened fitness advantages upon loss of tumor suppressor genes. Using an integrative multi-omic analysis, we confirm nucleotide pool insufficiency as a key contributor to widespread cellular dysfunction in aneuploid HMECs with net copy number gain. While diploid cells can switch seamlessly between pyrimidine synthesis and salvage, cells with increased chromosomal content exhibit p53 activation and S-phase arrest when relying on salvage alone, and exhibit increased sensitivity to DNA-damaging chemotherapeutics. This work advances our understanding of the consequences of aneuploidy and uncovers potential avenues for patient stratification and therapeutic intervention based on tumor ploidy.

cancer biology↗

bioRxiv2022

A novel batokine Breg controls adipose thermogenesis and glucose homeostasis

Batokines selectively expressed in brown and beige adipocytes remain to be identified and their potential signaling role in adipose thermogenesis are largely unknown. Here we identified a batokine we named as Breg acting as a key regulator for adipose thermogenesis and glucose homeostasis. Breg expression is adipose-specific and highly brown fat-enriched, and its secretion is stimulated by {beta}3-adrenergic activation. Gain-of-functional studies collectively showed that secreted Breg promotes adipose thermogenesis, lowers glucose level, and protects against obesity. Adipose-specific Breg knockout mice are defective in white fat browning, and are susceptible to high fat diet-induced obesity and hyperglycemia, demonstrating the physiological importance of this batokine in energy metabolism. Mechanistically, Breg binds to a putative receptor on adipocyte surface and activates protein kinase A independently of {beta}-adrenergic signaling. These results establish Breg as a major upstream signaling component in thermogenesis and offer a potential avenue for the treatment of obesity and diabetes.

cell biology↗