Project description:Brown adipose tissue (BAT) generates heat via uncoupled respiration, providing mammals with an evolutionary defense against environmental cold. Although the molecular pathways by which cold activates brown adipocytes are well understood, little is known about how BAT maintains its thermogenic capacity during adaptation to environmental warmth. Here, we identify the transcriptional repressor BCL6 as the switch for maintaining brown adipocyte cellular identity under warm conditions. Mice lacking BCL6 in their brown adipocytes display normal thermogenic responses when housed in a cool environment, but fail to maintain thermogenic fitness when housed under warm conditions. In a temperature-dependent manner, BCL6 suppresses apoptosis, fatty acid storage, and coupled respiration to maintain thermogenic competence in brown adipocytes. Enhancer analysis revealed that BCL6 reinforces brown-specific while opposing white-specific enhancers to maintain cellular identity. Thus, unlike other regulators, BCL6 is dispensable for differentiation and activation of brown adipocytes, but specifically required for their maintenance in warmth.
Project description:In adipocyte-specific knockout mice (Bcl6AKO), we found that Bcl6 deletion results in strikingly increased inguinal but not perigonadal adipocyte size and tissue mass in addition to marked insulin sensitivity. Genome-wide DNA binding and RNA expression analyses revealed that BCL6 controls gene networks involved in cell growth and fatty acid biosynthesis. Thus, our studies identify BCL6 as a negative regulator of subcutaneous adipose tissue expansion and metabolic health.
Project description:In adipocyte-specific knockout mice (Bcl6AKO), we found that Bcl6 deletion results in strikingly increased inguinal but not perigonadal adipocyte size and tissue mass in addition to marked insulin sensitivity. Genome-wide DNA binding and RNA expression analyses revealed that BCL6 controls gene networks involved in cell growth and fatty acid biosynthesis. Thus, our studies identify BCL6 as a negative regulator of subcutaneous adipose tissue expansion and metabolic health.
Project description:Most small-molecule protein degraders act as interface stabilizers ‘molecular glues’ between E3 ubiquitin ligases and target proteins to induce ternary complex formation and ubiquitin-dependent target protein degradation. Here we report polymerization as a novel mechanism for small molecule-induced degradation. Using functional screens in combination with molecular and biochemical assays, we found that BI-3802, which binds to the BTB domain of the oncogenic transcription factor BCL6, induces polymerization of BCL6 into regular helical structures in vitro and foci in vivo. Polymerization precedes degradation by the SIAH1 E3 ubiquitin ligase. Hereby, a VxP amino acid motif on BCL6, distal from the drug-binding BTB domain, is required for SIAH1 binding, ubiquitination and BI-3802-induced degradation. Our findings propose that small molecule-induced polymerization is not only a new modality for targeted protein degradation, but also provides synthetic biology with a tool for tunable protein polymerization and opens new avenues for future drug design.
Project description:We aimed to identify the response mechanism to EGFR tyrosine kinase inhibition. A431 cells were transfected with mock siRNA or BCL6 siRNA. Cells were then treated with gefitinib. Harvesting was done at 0h, at 24h and at 48h. Two TMT10plex sets were organized as follows: TMT set1: mock 0h (3x, channels 126, 127N and 127C), mock 24h (3x, 128N, 128C and 129N), mock 48h (3x, 129C, 130N, 130C) and internal pooled standard (131) composed from equal aliquots of all samples (mock siRNA and BCL6 siRNA). TMT set2: siBCL6 0h (3x, channels 126, 127N and 127C), siBCL6 24h (3x, 128N, 128C and 129N), siBCL6 48h (3x, 129C, 130N, 130C) and the same internal pooled standard (131) as for set 1.
Project description:gene expression data from wild-type and Bcl6-/- regulatory T cells in order to find genes regulated by Bcl6 in Treg cells FoxP3+ Tregs were sorted from wild-type (WT) and Bcl6-/- (KO) mice-- 8 samples, 2 from each type of Treg, 2 WT and 2 KO
Project description:FACS-purified adipocyte progenitors from murine subcutaneous adipose tissue were cultured under conditions promoting general adipogenic differentiation or beige/brite adipocyte differentiation (treatment with cPGI2). Time course expression profiling was performed during differentiation. In addition, some cultures of differentiated adipocytes were stimulated with norepinephrine for 3 hours. In parallel, differentiation and norepinephrine stimulation of progenitors from interscapular brown fat was performed and profiled.
Project description:To elucidate the mechanism of BCL6-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed BCL6+/+ and BCL6-/- B cell precursors. Pharmacological inhibition of BCR-ABL1 was performed with the BCR-ABL1 kinase inhibitor STI571 (Imatinib). BCR-ABL1 transformed B cell precursors of BCL6 wildtype and BCL6 knockout mice were either treated with 10µM STI571 (Imatinib) for 16 hours or cultured in absence of STI571. Three samples for each condition were processed.