Biology subjects

Calhoun, R.

Publications and source records attributed to Calhoun, R..

4 recordsLinked to original sources

bioRxiv2026

SOX4 Reprograms Adipose Stromal Cells into a Cancer-Associated Fibroblast-like State to Drive Metabolic Disease

Pathogenic adipose tissue remodeling promotes metabolic disease in obesity, but the mechanisms that establish this unhealthy tissue state remain poorly understood. Here, we show that obesity drives SOX4-dependent reprogramming of mesenchymal stromal cells (MSCs) into cancer-associated fibroblast-like (CAF-like) cells that promote adipose tissue dysfunction. TGF{beta} signaling is elevated in obesity and activates SOX4 in mouse and human MSCs, inducing their conversion to a CAF-like state. In mice, MSC-specific SOX4 activation induces the CAF-like program and exacerbates adipose tissue inflammation and glucose intolerance, whereas Sox4 deletion attenuates inflammation and improves glucose homeostasis during obesity. We further identify the growth factor Midkine (MDK) as a SOX4-regulated paracrine effector produced by CAF-like cells. MDK inhibition in obese mice reduces adipose tissue inflammation and improves metabolic function. Together, these findings define a TGF{beta}-SOX4-MDK stromal signaling axis that drives pathological adipose tissue remodeling in obesity and highlight this pathway as a potential therapeutic target for improving metabolic health.

cell biology↗

bioRxiv2026

Metabolic responses to physiological stressors assessed using continuous glucose monitoring integrated with indirect calorimetry in mice

Continuous glucose monitoring (CGM) in rodents has provided unprecedented temporal resolution of glycemic dynamics in vivo. Even in the absence of deliberate perturbation, glucose levels in mice are dynamic, fluctuating in response to the timing and duration of feeding events, changes in neurological and hormonal states, physical activity, and photoperiod. To obtain a comprehensive view of metabolic adaptations under common experimental conditions, we monitored freely moving mice simultaneously using CGM and indirect calorimetry to quantify glucose, food intake, physical activity and metabolic rate. We characterized glycemic and metabolic responses to routine laboratory interventions, including short-term and overnight fasting, refeeding, tail blood sampling during glucose tolerance tests, changes in ambient temperature to cold or thermoneutral conditions, and access to running wheels. We found that food removal induced a robust, transient stress response characterized by increased blood glucose, body temperature, energy expenditure, and physical activity. However, prolonged fasting ultimately led to hypoglycemia and torpor. The magnitude and variability of glycemic responses to insulin tolerance tests were strongly influenced by fasting duration, and tail-tip blood collection itself elicited substantial hyperglycemia. In contrast to prolonged fasting, refeeding produced relatively modest and transient effects on glucose and energy expenditure. Cold exposure elicited increased energy expenditure along with a sustained hyperglycemic response. Voluntary wheel running induced transient increases in glucose and metabolic activity and promoted a shift toward increased fatty acid oxidation. Together, these findings demonstrate that common laboratory manipulations exert dynamic, often substantial effects on glycemia and whole-body metabolism that are readily revealed by CGM and indirect calorimetry.

physiology↗

bioRxiv2024

Transcriptional regulation of adipocyte lipolysis by IRF2BP2

Adipocyte lipolysis controls systemic energy levels and metabolic homeostasis. Lipolysis is regulated by post-translational modifications of key lipolytic enzymes. However, less is known about the transcriptional mechanisms that regulate lipolysis. Here, we identify the transcriptional factor interferon regulatory factor-2 binding protein 2 (IRF2BP2) as a repressor of adipocyte lipolysis. Deletion of IRF2BP2 in primary human adipocytes increases lipolysis without affecting glucose uptake, whereas IRF2BP2 overexpression decreases lipolysis. RNA-seq and ChIP-seq analyses reveal that IRF2BP2 directly represses several lipolysis-related genes, including LIPE (HSL, hormone sensitive lipase), which encodes the rate-limiting enzyme in lipolysis. Adipocyte-selective deletion of Irf2bp2 in mice increases Lipe expression and free fatty acid levels, resulting in elevated adipose tissue inflammation and glucose intolerance. Altogether, these findings demonstrate that IRF2BP2 restrains adipocyte lipolysis and opens new avenues to target lipolysis for the treatment of metabolic disease.

molecular biology↗

bioRxiv2023

Sale of critically endangered sharks in the United States

Shark meat is widely available in the United States in grocery stores and seafood markets. The meat is often mislabeled or generically labeled as "shark". The ambiguity of these generic labels makes it challenging to assess the conservation implications of this practice and for consumers to avoid species with high mercury concentrations. For this study we purchased and DNA barcoded 30 shark products purchased in the United States to determine their species identity and conservation status. These samples consisted of 19 filets sold in grocery stores, seafood markets, and Asian specialty markets (mostly in North Carolina) and 11 ordered online as "jerky". 70% of samples were "soft mislabeled" (i.e., labeled generically as shark but not as a specific species). Of the nine samples labeled to species, eight were mislabeled (e.g., spinner shark labeled as mako shark). Only one sample was correctly labeled. All 30 samples were identified as shark and came from 11 different species, including three species listed by the IUCN as Critically Endangered: great hammerhead, scalloped hammerhead, and tope. The first two species have been found to contain very high levels of mercury, illustrating the implications of seafood mislabeling for human health. The widespread availability of shark meat in U.S. grocery stores is surprising given the dramatic decline of shark populations globally. Moreover, the fact that nearly all shark meat is either mislabeled or not labeled to species amplifies the problem. Accurate, verified product labels for shark meat would benefit consumers and shark conservation efforts, and should be a priority for the seafood industry.

genetics↗