@article{GrajaGarciaCarrizoJanketal.2018, author = {Graja, Antonia and Garcia-Carrizo, Francisco and Jank, Anne-Marie and Gohlke, Sabrina and Ambrosi, Thomas H. and Jonas, Wenke and Ussar, Siegfried and Kern, Matthias and Sch{\"u}rmann, Annette and Aleksandrova, Krasimira and Bluher, Matthias and Schulz, Tim Julius}, title = {Loss of periostin occurs in aging adipose tissue of mice and its genetic ablation impairs adipose tissue lipid metabolism}, series = {Aging Cell}, volume = {17}, journal = {Aging Cell}, number = {5}, publisher = {Wiley}, address = {Hoboken}, issn = {1474-9718}, doi = {10.1111/acel.12810}, pages = {13}, year = {2018}, abstract = {Remodeling of the extracellular matrix is a key component of the metabolic adaptations of adipose tissue in response to dietary and physiological challenges. Disruption of its integrity is a well-known aspect of adipose tissue dysfunction, for instance, during aging and obesity. Adipocyte regeneration from a tissue-resident pool of mesenchymal stem cells is part of normal tissue homeostasis. Among the pathophysiological consequences of adipogenic stem cell aging, characteristic changes in the secretory phenotype, which includes matrix-modifying proteins, have been described. Here, we show that the expression of the matricellular protein periostin, a component of the extracellular matrix produced and secreted by adipose tissue-resident interstitial cells, is markedly decreased in aged brown and white adipose tissue depots. Using a mouse model, we demonstrate that the adaptation of adipose tissue to adrenergic stimulation and high-fat diet feeding is impaired in animals with systemic ablation of the gene encoding for periostin. Our data suggest that loss of periostin attenuates lipid metabolism in adipose tissue, thus recapitulating one aspect of age-related metabolic dysfunction. In human white adipose tissue, periostin expression showed an unexpected positive correlation with age of study participants. This correlation, however, was no longer evident after adjusting for BMI or plasma lipid and liver function biomarkers. These findings taken together suggest that age-related alterations of the adipose tissue extracellular matrix may contribute to the development of metabolic disease by negatively affecting nutrient homeostasis.}, language = {en} } @article{GohlkeManciniGarciaCarrizoetal.2021, author = {Gohlke, Sabrina and Mancini, Carola and Garcia-Carrizo, Francisco and Schulz, Tim J.}, title = {Loss of the ciliary gene Bbs4 results in defective thermogenesis due to metabolic inefficiency and impaired lipid metabolism}, series = {The FASEB journal : the official journal of the Federation of American Societies for Experimental Biology}, volume = {35}, journal = {The FASEB journal : the official journal of the Federation of American Societies for Experimental Biology}, number = {11}, publisher = {Wiley}, address = {Hoboken}, issn = {1530-6860}, doi = {10.1096/fj.202100772RR}, pages = {13}, year = {2021}, abstract = {Adipose tissue is central to the regulation of energy balance. While white adipose tissue (WAT) is responsible for triglyceride storage, brown adipose tissue specializes in energy expenditure. Deterioration of brown adipocyte function contributes to the development of metabolic complications like obesity and diabetes. These disorders are also leading symptoms of the Bardet-Biedl syndrome (BBS), a hereditary disorder in humans which is caused by dysfunctions of the primary cilium and which therefore belongs to the group of ciliopathies. The cilium is a hair-like organelle involved in cellular signal transduction. The BBSome, a supercomplex of several Bbs gene products, localizes to the basal body of cilia and is thought to be involved in protein sorting to and from the ciliary membrane. The effects of a functional BBSome on energy metabolism and lipid mobilization in brown and white adipocytes were tested in whole-body Bbs4 knockout mice that were subjected to metabolic challenges. Chronic cold exposure reveals cold-intolerance of knockout mice but also ameliorates the markers of metabolic pathology detected in knockouts prior to cold. Hepatic triglyceride content is markedly reduced in knockout mice while circulating lipids are elevated, altogether suggesting that defective lipid metabolism in adipose tissue creates increased demand for systemic lipid mobilization to meet energetic demands of reduced body temperatures. These findings taken together suggest that Bbs4 is essential for the regulation of adipose tissue lipid metabolism, representing a potential target to treat metabolic disorders.}, language = {en} } @article{AgaBarfknechtSoultoukisStadionetal.2022, author = {Aga-Barfknecht, Heja and Soultoukis, George A. and Stadion, Mandy and Garcia-Carrizo, Francisco and J{\"a}hnert, Markus and Gottmann, Pascal and Vogel, Heike and Schulz, Tim Julius and Sch{\"u}rmann, Annette}, title = {Distinct adipogenic and fibrogenic differentiation capacities of mesenchymal stromal cells from pancreas and white adipose tissue}, series = {International journal of molecular sciences}, volume = {23}, journal = {International journal of molecular sciences}, number = {4}, publisher = {Molecular Diversity Preservation International}, address = {Basel}, issn = {1422-0067}, doi = {10.3390/ijms23042108}, pages = {21}, year = {2022}, abstract = {Pancreatic steatosis associates with beta-cell failure and may participate in the development of type-2-diabetes. Our previous studies have shown that diabetes-susceptible mice accumulate more adipocytes in the pancreas than diabetes-resistant mice. In addition, we have demonstrated that the co-culture of pancreatic islets and adipocytes affect insulin secretion. The aim of this current study was to elucidate if and to what extent pancreas-resident mesenchymal stromal cells (MSCs) with adipogenic progenitor potential differ from the corresponding stromal-type cells of the inguinal white adipose tissue (iWAT). miRNA (miRNome) and mRNA expression (transcriptome) analyses of MSCs isolated by flow cytometry of both tissues revealed 121 differentially expressed miRNAs and 1227 differentially expressed genes (DEGs). Target prediction analysis estimated 510 DEGs to be regulated by 58 differentially expressed miRNAs. Pathway analyses of DEGs and miRNA target genes showed unique transcriptional and miRNA signatures in pancreas (pMSCs) and iWAT MSCs (iwatMSCs), for instance fibrogenic and adipogenic differentiation, respectively. Accordingly, iwatMSCs revealed a higher adipogenic lineage commitment, whereas pMSCs showed an elevated fibrogenesis. As a low degree of adipogenesis was also observed in pMSCs of diabetes-susceptible mice, we conclude that the development of pancreatic steatosis has to be induced by other factors not related to cell-autonomous transcriptomic changes and miRNA-based signals.}, language = {en} }