LEF/TCFs direct the final step in Wnt/β-catenin signalling by recruiting β-catenin to genes for a... more LEF/TCFs direct the final step in Wnt/β-catenin signalling by recruiting β-catenin to genes for activation of transcription. Ancient, non-vertebrate TCFs contain two DNA binding domains, a High Mobility Group box for recognition of the Wnt Response Element (WRE; 5'-CTTTGWWS-3') and the C-clamp domain for recognition of the GC-rich Helper motif (5'-RCCGCC-3'). Two vertebrate TCFs (TCF-1/TCF7 and TCF-4/TCF7L2) use the C-clamp as an alternatively spliced domain to regulate cell-cycle progression, but how the C-clamp influences TCF binding and activity genome-wide is not known. Here, we used a doxycycline inducible system with ChIP-seq to assess how the C-clamp influences human TCF1 binding genome-wide. Metabolic pulse-labeling of nascent RNA with 4'Thiouridine was used with RNA-seq to connect binding to the Wnt transcriptome. We find that the C-clamp enables targeting to a greater number of gene loci for stronger occupancy and transcription regulation. The C-clamp u...
Much of the mechanism by which Wnt signaling drives proliferation during oncogenesis is attribute... more Much of the mechanism by which Wnt signaling drives proliferation during oncogenesis is attributed to its regulation of the cell cycle. Here, we show how Wnt/β-catenin signaling directs another hallmark of tumorigenesis, namely Warburg metabolism. Using biochemical assays and fluorescence lifetime imaging microscopy (FLIM) to probe metabolism in vitro and in living tumors, we observe that interference with Wnt signaling in colon cancer cells reduces glycolytic metabolism and results in small, poorly perfused tumors. We identify pyruvate dehydrogenase kinase 1 (PDK1) as an important direct target within a larger gene program for metabolism. PDK1 inhibits pyruvate flux to mitochondrial respiration and a rescue of its expression in Wnt-inhibited cancer cells rescues glycolysis as well as vessel growth in the tumor microenvironment. Thus, we identify an important mechanism by which Wnt-driven Warburg metabolism directs the use of glucose for cancer cell proliferation and links it to ves...
Issue: Public health researchers have repeatedly shown needle exchange programs (NEPs) to be effe... more Issue: Public health researchers have repeatedly shown needle exchange programs (NEPs) to be effective, cost-efficient tools to combat HIV and hepatitis C while connecting injection drug users (IDUs) to resources. However, despite decades of evidence, the United States has a national ban on federal funding for NEPs, harm reduction programs are illegal in many states, and local opposition can prevent the implementation of programs even where they are legal. Overcoming these obstacles can be easier with an understanding of alternative legal, research, and community organization approaches. Description: The Orange County Needle Exchange Program is a volunteer-run, student-organized, consensus-driven needle exchange implemented in Orange County, a conservative region of California. Our program has overcome substantial local opposition to harm reduction efforts and limited funding through working with state public health, building a diverse, strong community coalition, support from other...
LEF/TCFs direct the final step in Wnt/β-catenin signalling by recruiting β-catenin to genes for a... more LEF/TCFs direct the final step in Wnt/β-catenin signalling by recruiting β-catenin to genes for activation of transcription. Ancient, non-vertebrate TCFs contain two DNA binding domains, a High Mobility Group box for recognition of the Wnt Response Element (WRE; 5'-CTTTGWWS-3') and the C-clamp domain for recognition of the GC-rich Helper motif (5'-RCCGCC-3'). Two vertebrate TCFs (TCF-1/TCF7 and TCF-4/TCF7L2) use the C-clamp as an alternatively spliced domain to regulate cell-cycle progression, but how the C-clamp influences TCF binding and activity genome-wide is not known. Here, we used a doxycycline inducible system with ChIP-seq to assess how the C-clamp influences human TCF1 binding genome-wide. Metabolic pulse-labeling of nascent RNA with 4'Thiouridine was used with RNA-seq to connect binding to the Wnt transcriptome. We find that the C-clamp enables targeting to a greater number of gene loci for stronger occupancy and transcription regulation. The C-clamp u...
Much of the mechanism by which Wnt signaling drives proliferation during oncogenesis is attribute... more Much of the mechanism by which Wnt signaling drives proliferation during oncogenesis is attributed to its regulation of the cell cycle. Here, we show how Wnt/β-catenin signaling directs another hallmark of tumorigenesis, namely Warburg metabolism. Using biochemical assays and fluorescence lifetime imaging microscopy (FLIM) to probe metabolism in vitro and in living tumors, we observe that interference with Wnt signaling in colon cancer cells reduces glycolytic metabolism and results in small, poorly perfused tumors. We identify pyruvate dehydrogenase kinase 1 (PDK1) as an important direct target within a larger gene program for metabolism. PDK1 inhibits pyruvate flux to mitochondrial respiration and a rescue of its expression in Wnt-inhibited cancer cells rescues glycolysis as well as vessel growth in the tumor microenvironment. Thus, we identify an important mechanism by which Wnt-driven Warburg metabolism directs the use of glucose for cancer cell proliferation and links it to ves...
Issue: Public health researchers have repeatedly shown needle exchange programs (NEPs) to be effe... more Issue: Public health researchers have repeatedly shown needle exchange programs (NEPs) to be effective, cost-efficient tools to combat HIV and hepatitis C while connecting injection drug users (IDUs) to resources. However, despite decades of evidence, the United States has a national ban on federal funding for NEPs, harm reduction programs are illegal in many states, and local opposition can prevent the implementation of programs even where they are legal. Overcoming these obstacles can be easier with an understanding of alternative legal, research, and community organization approaches. Description: The Orange County Needle Exchange Program is a volunteer-run, student-organized, consensus-driven needle exchange implemented in Orange County, a conservative region of California. Our program has overcome substantial local opposition to harm reduction efforts and limited funding through working with state public health, building a diverse, strong community coalition, support from other...
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