Zfp516, a brown fat (BAT)-enriched and cold-inducible transcription factor, promotes transcription of UCP1 and other BAT-enriched genes for non-shivering thermogenesis. Here, we identify ...lysine-specific demethylase 1 (LSD1) as a direct binding partner of Zfp516. We show that, through interaction with Zfp516, LSD1 is recruited to UCP1 and other BAT-enriched genes, such as PGC1α, to function as a coactivator by demethylating H3K9. We also show that LSD1 is induced during brown adipogenesis and that LSD1 and its demethylase activity is required for the BAT program. Furthermore, we show that LSD1 ablation in mice using Myf5-Cre alters embryonic BAT development. Moreover, BAT-specific deletion of LSD1 via the use of UCP1-Cre impairs the BAT program and BAT development, making BAT resemble WAT, reducing thermogenic activity and promoting obesity. Finally, we demonstrate an in vivo requirement of the Zfp516-LSD1 interaction for LSD1 function in BAT gene activation.
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•Zfp516 recruits LSD1 at the UCP1 promoter, where it demethylates H3K9•LSD1 cooperates with Zfp516 to activate BAT genes and to promote thermogenesis•LSD1 ablation in brown adipose precursors impairs embryonic development of BAT•LSD1 ablation prevents browning of subcutaneous WAT induced by Zfp516
Sambeat et al. report that Zfp516, critical for activation of BAT gene program and thermogenesis, directly interacts with LSD1 for recruitment to BAT-enriched thermogenic genes. LSD1 demethylates H3K9 at the promoter regions of BAT-enriched genes. The authors also show that LSD1 is required during embryonic BAT development and for Zfp516-induced browning of WAT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Organ-on-a-chip systems possess a promising future as drug screening assays and as testbeds for disease modeling in the context of both single-organ systems and multi-organ-chips. Although it ...comprises approximately one fourth of the body weight of a healthy human, an organ frequently overlooked in this context is white adipose tissue (WAT). WAT-on-a-chip systems are required to create safety profiles of a large number of drugs due to their interactions with adipose tissue and other organs
via
paracrine signals, fatty acid release, and drug levels through sequestration. We report a WAT-on-a-chip system with a footprint of less than 1 mm
2
consisting of a separate media channel and WAT chamber connected
via
small micropores. Analogous to the
in vivo
blood circulation, convective transport is thereby confined to the vasculature-like structures and the tissues protected from shear stresses. Numerical and analytical modeling revealed that the flow rates in the WAT chambers are less than 1/100 of the input flow rate. Using optimized injection parameters, we were able to inject pre-adipocytes, which subsequently formed adipose tissue featuring fully functional lipid metabolism. The physiologically relevant microfluidic environment of the WAT-chip supported long term culture of the functional adipose tissue for more than two weeks. Due to its physiological, highly controlled, and computationally predictable character, the system has the potential to be a powerful tool for the study of adipose tissue associated diseases such as obesity and type 2 diabetes.
Organs-on-a-chip possess a promising future as drug screening assays and testbeds for disease modeling in the context of both single-organ systems and multi-organ-chips.
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. ...Here, we demonstrate that BAT utilizes actomyosin machinery to generate tensional responses following adrenergic stimulation, similar to muscle tissues. The activation of actomyosin mechanics is critical for the acute induction of oxidative metabolism and uncoupled respiration in UCP1+ adipocytes. Moreover, we show that actomyosin-mediated elasticity regulates the thermogenic capacity of adipocytes via the mechanosensitive transcriptional co-activators YAP and TAZ, which are indispensable for normal BAT function. These biomechanical signaling mechanisms may inform future strategies to promote the expansion and activation of brown/beige adipocytes.
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•BAT adrenergic stimulation induces an actomyosin-based mechanical response•Modulation of actomyosin responses alters oxidative metabolism in adipocytes•Thermogenic gene expression in adipocytes is in part regulated by YAP/TAZ
Tharp et al. show that brown adipocytes engage tensional actomyosin machinery, similar to muscle tissues, following adrenergic stimulation to mediate the thermogenic program and normal BAT function. These effects are mechanistically mediated through the YAP/TAZ pathway and, on a broad level, highlight the importance of cellular mechanics for cell metabolism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Double‐allylation reagents allow for the construction of highly complex molecules in an expedient fashion. We have developed an efficient, modular, and enantioselective approach towards accessing ...novel variants of these reagents through Cu/Pd‐catalyzed alkenylboration of alkenylboron derivatives. Importantly, we demonstrate novel use of an allylBdan reagent directly in a stereocontrolled allylation without initial deprotection to the boronic ester. These allylation products are employed in a second intermolecular allylation to access complex diol motifs, which has yet to be shown with these types of double‐allylation reagents. Overall, the modularity of this approach and the ease in which complex structural motifs can be accessed in a rapid manner signify the importance and utility of this method.
Make it a double: A strategy for the synthesis of novel double‐allylation reagents based on the alkenylboration of alkenylboronates is presented. The ease and modularity with which the reagents can be prepared allows rapid access to a variety of complex diol motifs. In the context of these studies, we also demonstrate the first examples of the use of boronamides in allylation reactions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract A critical design parameter for the function of synthetic extracellular matrices is to synchronize the gradual cell-mediated degradation of the matrix with the endogenous secretion of ...natural extracellular matrix (ECM) (e.g., creeping substitution). In hyaluronic acid (HyA)-based hydrogel matrices, we have investigated the effects of peptide crosslinkers with different matrix metalloproteinases (MMP) sensitivities on network degradation and neovascularization in vivo . The HyA hydrogel matrices consisted of cell adhesive peptides, heparin for both the presentation of exogenous and sequestration of endogenously synthesized growth factors, and MMP cleavable peptide linkages (i.e., QPQGLAK, GPLGMHGK, and GPLGLSLGK). Sca1+ /CD45− /CD34+ /CD44+ cardiac progenitor cells (CPCs) cultured in the matrices with the slowly degradable QPQGLAK hydrogels supported the highest production of MMP-2, MMP-9, MMP-13, VEGF165 , and a range of angiogenesis related proteins. Hydrogels with QPQGLAK crosslinks supported prolonged retention of these proteins via heparin within the matrix, stimulating rapid vascular development, and anastomosis with the host vasculature when implanted in the murine hindlimb.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Novel, clinically relevant, approaches to shift energy balance are urgently needed to combat metabolic disorders such as obesity and diabetes. One promising approach has been the expansion of brown ...adipose tissues that express uncoupling protein (UCP) 1 and thus can uncouple mitochondrial respiration from ATP synthesis. While expansion of UCP1-expressing adipose depots may be achieved in rodents via genetic and pharmacological manipulations or the transplantation of brown fat depots, these methods are difficult to use for human clinical intervention. We present a novel cell scaffold technology optimized to establish functional brown fat-like depots in vivo. We adapted the biophysical properties of hyaluronic acid-based hydrogels to support the differentiation of white adipose tissue-derived multipotent stem cells (ADMSCs) into lipid-accumulating, UCP1-expressing beige adipose tissue. Subcutaneous implantation of ADMSCs within optimized hydrogels resulted in the establishment of distinct UCP1-expressing implants that successfully attracted host vasculature and persisted for several weeks. Importantly, implant recipients demonstrated elevated core body temperature during cold challenges, enhanced respiration rates, improved glucose homeostasis, and reduced weight gain, demonstrating the therapeutic merit of this highly translatable approach. This novel approach is the first truly clinically translatable system to unlock the therapeutic potential of brown fat-like tissue expansion.
Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the most prevalent types of primary liver cancer. These malignancies have limited treatment options, resulting in poor ...patient outcomes. Metabolism reprogramming, including increased de novo lipogenesis, is one of the hallmarks of cancer. Fatty acid synthase (FASN) catalyzes the de novo synthesis of long‐chain fatty acids from acetyl‐coenzyme A and malonyl‐coenzyme A. Increased FASN expression has been reported in multiple tumor types, and inhibition of FASN expression has been shown to have tumor‐suppressing activity. Intriguingly, we found that while FASN is up‐regulated in human HCC samples, its expression is frequently low in human ICC specimens. Similar results were observed in mouse ICC models induced by different oncogenes. Ablating FASN in the mouse liver did not affect activated AKT and Notch (AKT/Notch intracellular domain 1) induced ICC formation in vivo. Furthermore, while both HCC and ICC lesions develop in mice following hydrodynamic injection of AKT and neuroblastoma Ras viral oncogene homolog oncogenes (AKT/Ras), deletion of FASN in AKT/Ras mice triggered the development almost exclusively of ICCs. In the absence of FASN, ICC cells might receive lipids for membrane synthesis through exogenous fatty acid uptake. In accordance with the latter hypothesis, ICC cells displayed high expression of fatty acid uptake‐related proteins and robust long‐chain fatty acid uptake. Conclusion: Our data demonstrate that FASN dependence is not a universal feature of liver tumors: while HCC development is highly dependent of FASN and its mediated lipogenesis, ICC tumorigenesis can be insensitive to FASN deprivation; our study supports novel therapeutic approaches to treat this pernicious tumor type with the inhibition of exogenous fatty acid uptake. (Hepatology 2016;63:1900‐1913)
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Modeling Tissue Polarity in Context Tharp, Kevin M.; Weaver, Valerie M.
Journal of Molecular Biology/Journal of molecular biology,
09/2018, Volume:
430, Issue:
19
Journal Article
Peer reviewed
Open access
Polarity is critical for development and tissue-specific function. However, the acquisition and maintenance of tissue polarity is context dependent. Thus, cell and tissue polarity depend on cell ...adhesion which is regulated by the cytoskeleton and influenced by the biochemical composition of the extracellular microenvironment and modified by biomechanical cues within the tissue. These biomechanical cues include fluid flow induced shear stresses, cell-density and confinement-mediated compression, and cellular actomyosin tension intrinsic to the tissue or induced in response to morphogens or extracellular matrix stiffness. Here, we discuss how extracellular matrix stiffness and fluid flow influence cell–cell and cell–extracellular matrix adhesion and alter cytoskeletal organization to modulate cell and tissue polarity. We describe model systems that when combined with state of the art molecular screens and high-resolution imaging can be used to investigate how force modulates cell and tissue polarity.
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•Cell and tissue polarity depend on cell adhesion.•Polarity instructing adhesions are affected by mechanical forces.•Mechanical cues within the microenvironment can disrupt polarity.•Descriptions of model systems to study mechanical forces and polarity
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Pre-metastatic niche formation is a critical step during the metastatic spread of cancer. One way by which primary tumors prime host cells at future metastatic sites is through the shedding of ...tumor-derived microparticles as a consequence of vascular sheer flow. However, it remains unclear how the uptake of such particles by resident immune cells affects their phenotype and function. Here, we show that ingestion of tumor-derived microparticles by macrophages induces a rapid metabolic and phenotypic switch that is characterized by enhanced mitochondrial mass and function, increased oxidative phosphorylation, and upregulation of adhesion molecules, resulting in reduced motility in the early metastatic lung. This reprogramming event is dependent on signaling through the mTORC1, but not the mTORC2, pathway and is induced by uptake of tumor-derived microparticles. Together, these data support a mechanism by which uptake of tumor-derived microparticles induces reprogramming of macrophages to shape their fate and function in the early metastatic lung.
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•Ingestion of tumor-derived material induces phenotypic reprogramming in macrophages•Macrophage reprogramming impacts patrolling behavior in response to tumor cells•ZsGreen+ macrophages show enhanced mitochondrial metabolism characterized by OXPHOS•mTORC1 is required for enhanced OXPHOS and ATP production in ZsGreen+ macrophages
Kersten et al. show that ingestion of tumor-derived microparticles induces a metabolic and phenotypic switch in non-alveolar inflammatory macrophages in the early metastatic lung. This mTORC1-dependent reprogramming event, characterized by increased OXPHOS, ATP production, and upregulation of adhesion molecules, dictates macrophage phenotype and function during metastasis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mitochondria control eukaryotic cell fate by producing the energy needed to support life and the signals required to execute programed cell death. The biochemical milieu is known to affect ...mitochondrial function and contribute to the dysfunctional mitochondrial phenotypes implicated in cancer and the morbidities of aging. However, the physical characteristics of the extracellular matrix are also altered in cancerous and aging tissues. Here, we demonstrate that cells sense the physical properties of the extracellular matrix and activate a mitochondrial stress response that adaptively tunes mitochondrial function via solute carrier family 9 member A1-dependent ion exchange and heat shock factor 1-dependent transcription. Overall, our data indicate that adhesion-mediated mechanosignaling may play an unappreciated role in the altered mitochondrial functions observed in aging and cancer.
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•Cell-ECM mechanosignaling influences mitochondrial structure and function•Cellular mechanosignaling activates an HSF1-mediated stress response•Stiff ECM alters redox homeostasis and metabolism via mitochondrial reprogramming•Stiff microenvironments confer redox stress resilience to cells via HSF1 and YME1L1
Tharp et al. demonstrate that adhesion-mediated mechanosignaling dictates cellular metabolic programing. Mechanosensitive ion exchange and an HSF1-mediated mitochondrial stress response alters metabolic programing of cells actively adapting to mechanically distinct microenvironments. These findings offer one explanation for metabolic phenotypes observed in some epithelial cells residing within fibrotic/stiffened tumor tissue microenvironments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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