@article {796, title = {Defective extracellular matrix remodeling in brown adipose tissue is associated with fibro-inflammation and reduced diet-induced thermogenesis.}, journal = {Cell Rep}, volume = {42}, year = {2023}, month = {2023 Jun 13}, pages = {112640}, abstract = {

The relevance of extracellular matrix (ECM) remodeling is reported in white adipose tissue (AT) and obesity-related dysfunctions, but little is known about the importance of ECM remodeling in brown AT (BAT) function. Here, we show that a time course of high-fat diet (HFD) feeding progressively impairs diet-induced thermogenesis concomitantly with the development of fibro-inflammation in BAT. Higher markers of fibro-inflammation are associated with lower cold-induced BAT activity in humans. Similarly, when mice are housed at thermoneutrality, inactivated BAT features fibro-inflammation. We validate the pathophysiological relevance of BAT ECM remodeling in response to temperature challenges and HFD using a model of a primary defect in the collagen turnover mediated by partial ablation of the Pepd prolidase. Pepd-heterozygous mice display exacerbated dysfunction and BAT fibro-inflammation at thermoneutrality and in HFD. Our findings show the relevance of ECM remodeling in BAT activation and provide a mechanism for BAT dysfunction in obesity.

}, issn = {2211-1247}, doi = {10.1016/j.celrep.2023.112640}, author = {Pellegrinelli, Vanessa and Figueroa-Ju{\'a}rez, Elizabeth and Samuelson, Isabella and U-Din, Mueez and Rodriguez-Fdez, Sonia and Virtue, Samuel and Leggat, Jennifer and Cubuk, Cankut and Peirce, Vivian J and Niemi, Tarja and Campbell, Mark and Rodriguez-Cuenca, Sergio and Dopazo, Joaquin and Carobbio, Stefania and Virtanen, Kirsi A and Vidal-Puig, Antonio} } @article {1198, title = {Chronic subordination stress selectively downregulates the insulin signaling pathway in liver and skeletal muscle but not in adipose tissue of male mice.}, journal = {Stress (Amsterdam, Netherlands)}, year = {2016}, month = {2016 Mar 7}, pages = {1-11}, abstract = {Chronic stress has been associated with obesity, glucose intolerance, and insulin resistance. We developed a model of chronic psychosocial stress (CPS) in which subordinate mice are vulnerable to obesity and the metabolic-like syndrome while dominant mice exhibit a healthy metabolic phenotype. Here we tested the hypothesis that the metabolic difference between subordinate and dominant mice is associated with changes in functional pathways relevant for insulin sensitivity, glucose and lipid homeostasis. Male mice were exposed to CPS for four weeks and fed either a standard diet or a high-fat diet (HFD). We first measured, by real-time PCR candidate genes, in the liver, skeletal muscle, and the perigonadal white adipose tissue (pWAT). Subsequently, we used a probabilistic analysis approach to analyze different ways in which signals can be transmitted across the pathways in each tissue. Results showed that subordinate mice displayed a drastic downregulation of the insulin pathway in liver and muscle, indicative of insulin resistance, already on standard diet. Conversely, pWAT showed molecular changes suggestive of facilitated fat deposition in an otherwise insulin-sensitive tissue. The molecular changes in subordinate mice fed a standard diet were greater compared to HFD-fed controls. Finally, dominant mice maintained a substantially normal metabolic and molecular phenotype even when fed a HFD. Overall, our data demonstrate that subordination stress is a potent stimulus for the downregulation of the insulin signaling pathway in liver and muscle and a major risk factor for the development of obesity, insulin resistance, and type 2 diabetes mellitus.}, keywords = {Adipose tissue, insulin, IRS1, IRS2, metabolic syndrome, obesity, pathway analysis}, issn = {1607-8888}, doi = {10.3109/10253890.2016.1151491}, url = {http://www.tandfonline.com/doi/abs/10.3109/10253890.2016.1151491?journalCode=ists20}, author = {Sanghez, Valentina and Cubuk, Cankut and Sebasti{\'a}n-Leon, Patricia and Carobbio, Stefania and Dopazo, Joaquin and Vidal-Puig, Antonio and Bartolomucci, Alessandro} } @article {451, title = {Stress-induced activation of brown adipose tissue prevents obesity in conditions of low adaptive thermogenesis.}, journal = {Mol Metab}, volume = {5}, year = {2016}, month = {2016 Jan}, pages = {19-33}, abstract = {

BACKGROUND: Stress-associated conditions such as psychoemotional reactivity and depression have been paradoxically linked to either weight gain or weight loss. This bi-directional effect of stress is not understood at the functional level. Here we tested the hypothesis that pre-stress level of adaptive thermogenesis and brown adipose tissue (BAT) functions explain the vulnerability or resilience to stress-induced obesity.

METHODS: We used wt and triple β1,β2,β3-Adrenergic Receptors knockout (β-less) mice exposed to a model of chronic subordination stress (CSS) at either room temperature (22~{\textdegree}C) or murine thermoneutrality (30~{\textdegree}C). A combined behavioral, physiological, molecular, and immunohistochemical analysis was conducted to determine stress-induced modulation of energy balance and BAT structure and function. Immortalized brown adipocytes were used for in~vitro assays.

RESULTS: Departing from our initial observation that βARs are dispensable for cold-induced BAT browning, we demonstrated that under physiological conditions promoting low adaptive thermogenesis and BAT activity (e.g. thermoneutrality or genetic deletion of the βARs), exposure to CSS acted as a stimulus for BAT activation and thermogenesis, resulting in resistance to diet-induced obesity despite the presence of hyperphagia. Conversely, in wt mice acclimatized to room temperature, and therefore characterized by sustained BAT function, exposure to CSS increased vulnerability to obesity. Exposure to CSS enhanced the sympathetic innervation of BAT in wt acclimatized to thermoneutrality and in β-less mice. Despite increased sympathetic innervation suggesting adrenergic-mediated browning, norepinephrine did not promote browning in βARs knockout brown adipocytes, which led us to identify an alternative sympathetic/brown adipocytes purinergic pathway in the BAT. This pathway is downregulated under conditions of low adaptive thermogenesis requirements, is induced by stress, and elicits activation of UCP1 in wt and β-less brown adipocytes. Importantly, this purinergic pathway is conserved in human BAT.

CONCLUSION: Our findings demonstrate that thermogenesis and BAT function are determinant of the resilience or vulnerability to stress-induced obesity. Our data support a model in which adrenergic and purinergic pathways exert complementary/synergistic functions in BAT, thus suggesting an alternative to βARs agonists for the activation of human BAT.

}, issn = {2212-8778}, doi = {10.1016/j.molmet.2015.10.005}, author = {Razzoli, Maria and Frontini, Andrea and Gurney, Allison and Mondini, Eleonora and Cubuk, Cankut and Katz, Liora S and Cero, Cheryl and Bolan, Patrick J and Dopazo, Joaquin and Vidal-Puig, Antonio and Cinti, Saverio and Bartolomucci, Alessandro} } @article {565, title = {Understanding disease mechanisms with models of signaling pathway activities}, journal = {BMC systems biology}, volume = {8}, year = {2014}, month = {10}, pages = {121}, doi = {10.1186/s12918-014-0121-3}, author = {Sebasti{\'a}n-Leon, Patricia and Vidal, Enrique and Minguez, Pablo and Conesa, Ana and Tarazona, Sonia and Amadoz, Alicia and Armero, Carmen and Salavert Torres, Francisco and Vidal-Puig, Antonio and Montaner, David and Dopazo, Joaquin} } @article {1093, title = {Understanding disease mechanisms with models of signaling pathway activities.}, journal = {BMC systems biology}, volume = {8}, year = {2014}, month = {2014 Oct 25}, pages = {121}, abstract = {BackgroundUnderstanding the aspects of the cell functionality that account for disease or drug action mechanisms is one of the main challenges in the analysis of genomic data and is on the basis of the future implementation of precision medicine.ResultsHere we propose a simple probabilistic model in which signaling pathways are separated into elementary sub-pathways or signal transmission circuits (which ultimately trigger cell functions) and then transforms gene expression measurements into probabilities of activation of such signal transmission circuits. Using this model, differential activation of such circuits between biological conditions can be estimated. Thus, circuit activation statuses can be interpreted as biomarkers that discriminate among the compared conditions. This type of mechanism-based biomarkers accounts for cell functional activities and can easily be associated to disease or drug action mechanisms. The accuracy of the proposed model is demonstrated with simulations and real datasets.ConclusionsThe proposed model provides detailed information that enables the interpretation disease mechanisms as a consequence of the complex combinations of altered gene expression values. Moreover, it offers a framework for suggesting possible ways of therapeutic intervention in a pathologically perturbed system.}, keywords = {Disease mechanism, pathway, signalling, Systems biology}, issn = {1752-0509}, doi = {10.1186/s12918-014-0121-3}, url = {http://www.biomedcentral.com/1752-0509/8/121/abstract}, author = {Sebasti{\'a}n-Leon, Patricia and Vidal, Enrique and Minguez, Pablo and Ana Conesa and Sonia Tarazona and Amadoz, Alicia and Armero, Carmen and Salavert, Francisco and Vidal-Puig, Antonio and Montaner, David and Joaqu{\'\i}n Dopazo} } @article {21266330, title = {Differential Lipid Partitioning Between Adipocytes and Tissue Macrophages Modulates Macrophage Lipotoxicity and M2/M1 Polarization in Obese Mice.}, journal = {Diabetes}, volume = {60}, number = {3}, year = {2011}, month = {2011 Jan 24}, pages = {797-809}, abstract = {

OBJECTIVE Obesity-associated insulin resistance is characterized by a state of chronic, low-grade inflammation that is associated with the accumulation of M1 proinflammatory macrophages in adipose tissue. Although different evidence explains the mechanisms linking the expansion of adipose tissue and adipose tissue macrophage (ATM) polarization, in the current study we investigated the concept of lipid-induced toxicity as the pathogenic link that could explain the trigger of this response. RESEARCH DESIGN AND METHODS We addressed this question using isolated ATMs and adipocytes from genetic and diet-induced murine models of obesity. Through transcriptomic and lipidomic analysis, we created a model integrating transcript and lipid species networks simultaneously occurring in adipocytes and ATMs and their reversibility by thiazolidinedione treatment. RESULTS We show that polarization of ATMs is associated with lipid accumulation and the consequent formation of foam cell-like cells in adipose tissue. Our study reveals that early stages of adipose tissue expansion are characterized by M2-polarized ATMs and that progressive lipid accumulation within ATMs heralds the M1 polarization, a macrophage phenotype associated with severe obesity and insulin resistance. Furthermore, rosiglitazone treatment, which promotes redistribution of lipids toward adipocytes and extends the M2 ATM polarization state, prevents the lipid alterations associated with M1 ATM polarization. CONCLUSIONS Our data indicate that the M1 ATM polarization in obesity might be a macrophage-specific manifestation of a more general lipotoxic pathogenic mechanism. This indicates that strategies to optimize fat deposition and repartitioning toward adipocytes might improve insulin sensitivity by preventing ATM lipotoxicity and M1 polarization.

}, author = {Prieur, Xavier and Mok, Crystal Y L and Velagapudi, Vidya R and N{\'u}{\~n}ez, Vanessa and Fuentes, Luc{\'\i}a and Montaner, David and Ishikawa, Ko and Camacho, Alberto and Barbarroja, Nuria and O{\textquoteright}Rahilly, Stephen and Sethi, Jaswinder and Dopazo, Joaquin and Oresic, Matej and Ricote, Mercedes and Vidal-Puig, Antonio} } @article {531, title = {Early peroxisome proliferator-activated receptor gamma regulated genes involved in expansion of pancreatic beta cell mass.}, journal = {BMC Med Genomics}, volume = {4}, year = {2011}, month = {2011 Dec 30}, pages = {86}, abstract = {

BACKGROUND: The progression towards type 2 diabetes depends on the allostatic response of pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physiological and pathophysiological states associated to insulin resistance such as pregnancy, obesity or ageing, but the mechanisms mediating beta cell mass expansion in these scenarios are not well defined. We have recently shown that ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse failed to expand its beta cell mass. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Thus, comparison of these models islets particularly at early ages could provide some new insights on early PPARγ dependent transcriptional responses involved in the process of beta cell mass expansion

RESULTS: Here we have investigated PPARγ dependent transcriptional responses occurring during the early stages of beta cell adaptation to insulin resistance in wild type, ob/ob, PPARγ2 KO and POKO mice. We have identified genes known to regulate both the rate of proliferation and the survival signals of beta cells. Moreover we have also identified new pathways induced in ob/ob islets that remained unchanged in POKO islets, suggesting an important role for PPARγ in maintenance/activation of mechanisms essential for the continued function of the beta cell.

CONCLUSIONS: Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with the activation of an immune response that fails to occur in POKO islets. We have also indentified other PPARγ dependent differentially regulated pathways including cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation.

}, keywords = {Animals, Cell Proliferation, Cell Survival, Cholesterol, Down-Regulation, Female, Gene Expression Regulation, Gene Knockout Techniques, Insulin Resistance, Insulin-Secreting Cells, Mice, obesity, Oxidation-Reduction, Phosphorylation, PPAR gamma, Signal Transduction, Transcription, Genetic, Transforming Growth Factor beta}, issn = {1755-8794}, doi = {10.1186/1755-8794-4-86}, author = {Vivas, Yurena and Martinez-Garcia, Cristina and Izquierdo, Adriana and Garcia-Garcia, Francisco and Callejas, Sergio and Velasco, Ismael and Campbell, Mark and Ros, Manuel and Dopazo, Ana and Dopazo, Joaquin and Vidal-Puig, Antonio and Medina-Gomez, Gema} }