Project description:The activation of brown/beige adipose tissue (BAT) metabolism and the induction of uncoupling protein-1 (UCP1) expression are essential for BAT-based strategies to improve metabolic homeostasis. Adrenergic signaling is viewed as a key regulator of thermogenesis and UCP1-expression in BAT, while also operating as a potent contractile stimulator in muscle. The muscle-like gene expression patterns of UCP1+ adipocytes have previously been utilized as tissue specific markers, but have not been attributed with any functional role. Here, we demonstrate that BAT utilizes actomyosin machinery to generate tensional responses following adrenergic stimulation, similar to muscle tissues. We show that activation of actomyosin mechanics are critical for the acute induction of oxidative metabolism and uncoupled respiration in UCP1+ adipocytes. Additionally, actomyosin-mediated elasticity regulates mechanosensitive transcriptional co-activators, YAP/TAZ, that facilitate the thermogenic capacity of adipocytes. These unappreciated signaling and mechanical mechanisms may inform future strategies to promote the expansion and activation of brown/beige adipocytes.
Project description:For placental mammals, the transition from the in utero maternal environment to postnatal life requires the activation of thermogenesis to maintain their core temperature. This is primarily accomplished by induction of uncoupling protein 1 (UCP1) in brown and beige adipocytes, the principal sites for uncoupled respiration. Despite its importance, how placental mammals license their thermogenic adipocytes to participate in postnatal uncoupled respiration is not known. Here, we provide evidence that the 'alarmin' IL-33, a nuclear cytokine that activates type 2 immune responses, licenses brown and beige adipocytes for uncoupled respiration. We find that, in absence of IL-33 or ST2, beige and brown adipocytes develop normally but fail to express an appropriately spliced form of Ucp1 mRNA, resulting in absence of UCP1 protein, and impairment in uncoupled respiration and thermoregulation. Together, these data suggest that IL-33 and ST2 function as a developmental switch to license thermogenesis during the perinatal period.
Project description:It has been a long-standing challenge to maintain the functions of hepatocytes in vitro. In the present study, we found that mechanical tension-induced yes-associated protein (Yap) activation triggered hepatocyte dedifferentiation. Alleviation of mechanical tension by confinement of cell spreading was sufficient to inhibit hepatocyte dedifferentiation. Based on this finding, we identified a small molecular cocktail LBDXL through reiterative chemical screening that could maintain hepatocyte functions over the long term and in vivo repopulation capacity by targeting actin polymerization and actomyosin contraction.
Project description:Human brown adipose tissue (BAT) has become an attractive target to combat the current epidemical spread of obesity and its associated co-morbidities. Currently, information on its functional role is primarily derived from rodent studies. Here, we present the first comparative proteotype analysis of primary human brown adipose tissue versus adjacent white adipose tissue, which reveals significant quantitative differences in protein abundances and in turn differential functional capabilities. The majority of the 318 proteins with increased abundance in BAT are associated with mitochondrial metabolism and confirm the increased oxidative capacity. In addition to uncoupling protein 1 (UCP1), the main functional effector for uncoupled respiration, we also detected the mitochondrial creatine kinases (CKMT1A/B, CKMT2), as effective modulators of ATP synthase coupled respiration, to be exclusively expressed in BAT. The abundant expression and utilization of both energy expenditure pathways in parallel highlights the complex functional involvement of BAT in human physiology.
Project description:One of the hallmarks in hypertension is a pressure-induced change in endothelial cell phenotype. A cytoskeletal protein zyxin, which was seen to translocate from focal adhesion contacts to the nucleus in response to the increased wall tensionis, mediates the tension-induced endothelial signaling. Microarrays were used to detail the role of zyxin in the tension-induced expression changes in endothelial cells. Primary endothelial cells (Huvec) from four treatment groups were used for RNA extraction and hybridization on Affymetrix microarrays: wild type under normal condition, wild type under tension, Zyxin-SiRNA-treated under normal condition and Zyxin-SiRNA-treated under tension.
Project description:Brown and beige fats generate heat via uncoupled respiration to defend against cold, mechanistically, through the action of a network of transcription factors and cofactors. Here we globally profiled long noncoding RNAs (lncRNAs) gene expression during thermogenic adipocyte formation and identified Brown fat lncRNA 1 (Blnc1) as a novel nuclear lncRNA that promotes brown and beige adipocyte differentiation and function by forming a feedforward regulatory loop with EBF2 to drive adipogenesis toward thermogenic phenotype. LncRNAs expression were measured in BAT and WAT from mice injected saline/CL and during brown adipocyte differentiation with two replicates using Arraystar Mouse LncRNA microarray V2.0
Project description:Hypertrophic scars arise from dysregulated wound healing under prolonged mechanical tension, causing disfiguring fibrosis. However, limited preclinical models replicate key features of human tension-induced scarring. We developed an innovative murine model utilizing suture anchoring to impose persistent transverse-axial stretch across healing incisions, mimicking excessive wound tension that leads to hypertrophy clinically. Dorsal paired incisions were generated in mice, with wound edges on the upper back sutured to the rib cage while leaving wound edges on the lower back relaxed. This localized anchoring restrained wound contraction, maintaining high tension throughout remodeling analogous to scars widening under stress. Stretched upper wounds developed profound fibrotic changes compared to relaxed controls. Scars induced by suture-anchored tension displayed macroscopic hypertrophy, hardness, erythema, and pruritis up to 3 months. Histologically, scars induced by suture-anchored tension were hypercellular, hypervascular, hyperproliferative with disorganized extracellular matrix deposition, and displayed molecular hallmarks of hypertrophic fibrosis. MiRNA sequencing revealed the different signature in suture-anchored tension induced hypertrophic scars compared to control normal scars.