Project description:Cre recombinase activity was induced in differentiating brown adipocytes from CreERT2 Sykflox/flox mice in vitro, which resulted in a partial loss of Syk protein in mature brown adipocytes. Such cells were viable, morphologically normal and displayed largely normal gene expression as indicated by mRNA sequencing and qPCR analysis, suggesting that Syk is not required for survival and gene expression of terminally differentiated brown adipocytes. mRNA sequencing of Syk depleted brown adipocytes treated with 0.1 microM isoproterenol for 6 h showed that 2460 genes were not induced or suppressed upon stimulation. Gene set enrichment analysis revealed a great enrichment for genes essential for mitochondrial respiration and biogenesis, for genes associated with and required for adipogenesis, as well as for genes responsive to various stimuli in adipocytes among genes highly ranked by reduced fold changes in response to isoproterenol in the Syk deficient brown adipocytes.
Project description:Brown adipose tissue (BAT) has in recent times been rediscovered in adult humans, and together with work from preclinical models, shown to have the potential of providing a variety of positive metabolic benefits. These include improved insulin sensitivity and reduced susceptibility to obesity and its various co-morbidities. As such, its continued study could offer insights to therapeutically modulate this tissue to improve metabolic health. It has been reported that adipose-specific deletion of the gene for protein kinase D1 (Prkd1) enhances mitochondrial respiration and improves whole-body glucose homeostasis. We sought to determine whether these effects were mediated specifically through brown adipocytes using a Prkd1 brown adipose tissue (BAT) Ucp1-Cre-specific knockout mouse model, Prkd1BKO. We unexpectedly observed that upon both cold exposure and beta-3-AR agonist administration, Prkd1 loss in BAT did not alter canonical thermogenic gene expression or adipocyte morphology. We took an unbiased approach to assess whether other signaling pathways were altered. RNAs from cold-exposed control and Prkd1BKO were subjected to RNA-Seq analysis. These studies revealed that myogenic gene expression is altered in Prkd1BKO BAT after both acute (8 hr) and extended (4 day) cold exposure. Given that brown adipocytes and skeletal myocytes share a common precursor cell lineage expressing myogenic factor 5 (Myf5), these data suggest that loss of Prkd1 in BAT may alter the biology of preadipocytes in this depot. The data presented herein clarify the role of Prkd1 in BAT thermogenesis and present new avenues for the further study of Prkd1 function in BAT.
Project description:The experiment was designed to determine the gene expression changes cultured brown adipocytes in response to the inflammatory stimulus of LPS treatment. Both wild type and TLR4 knockout cells were applied to enable assessment of the contribution of TLR4 to the response.
Project description:Histones were isolated from brown adipose tissue and liver from mice housed at 28, 22, or 8 C. Quantitative top- or middle-down approaches were used to quantitate histone H4 and H3.2 proteoforms. See published article for complimentary RNA-seq and RRBS datasets.
Project description:Increasing energy expenditure through activation of brown adipose tissue (BAT) thermogenesis is an attractive approach to counteract obesity. Thus, it is essential to understand molecular mechanisms that control BAT functions. Here, we describe signal transducer and activator of transcription (STAT) 5 as key regulator of BAT functionality. We found that STAT5 is necessary for acute cold-induced temperature maintenance and stimulated lipid breakdown in BAT using mice that harbour an adipocyte-specific deletion of Stat5a/b genes. In addition, the mitochondrial respiratory capacity of primary differentiated brown adipocytes from STAT5 deficient mice was diminished. We show that increased sensitivity to cold stress upon STAT5 deficiency was associated with reduced expression of thermogenic key player uncoupling protein 1, while decreased stimulated lipolysis of STAT5-deficient BAT explants was linked to decreased protein kinase A activity. In addition, brown remodeling of white fat was diminished following chronic β-adrenergic stimulation. This impairment was linked to a decrease in mitochondrial functionality. We conclude that STAT5 is essential for the β-adrenergic responsiveness of brown adipose tissue and the physiologic function of thermogenic adipose tissue.