RESUMO
Evolutionarily conserved SCAN (named after SRE-ZBP, CTfin51, AW-1, and Number 18 cDNA)-domain-containing zinc finger transcription factors (ZSCAN) have been found in both mouse and human genomes. Zscan4 is transiently expressed during zygotic genome activation (ZGA) in preimplantation embryos and induced pluripotent stem cell (iPSC) reprogramming. However, little is known about the mechanism of Zscan4 underlying these processes of cell fate control. Here, we show that Zscan4f, a representative of ZSCAN proteins, is able to recruit Tet2 through its SCAN domain. The Zscan4f-Tet2 interaction promotes DNA demethylation and regulates the expression of target genes, particularly those encoding glycolytic enzymes and proteasome subunits. Zscan4f regulates metabolic rewiring, enhances proteasome function, and ultimately promotes iPSC generation. These results identify Zscan4f as an important partner of Tet2 in regulating target genes and promoting iPSC generation and suggest a possible and common mechanism shared by SCAN family transcription factors to recruit ten-eleven translocation (TET) DNA dioxygenases to regulate diverse cellular processes, including reprogramming.
Assuntos
Reprogramação Celular/genética , Proteínas de Ligação a DNA/metabolismo , Proteostase/genética , Proteínas Proto-Oncogênicas/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Gênica , Animais , Sequência de Bases , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Dioxigenases , Glicólise/genética , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células MCF-7 , Camundongos Endogâmicos C57BL , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Domínios Proteicos , Proteínas Proto-Oncogênicas/genética , Regulação para CimaRESUMO
The TET2 DNA dioxygenase regulates gene expression by catalyzing demethylation of 5-methylcytosine, thus epigenetically modulating the genome. TET2 does not contain a sequence-specific DNA-binding domain, and how it is recruited to specific genomic sites is not fully understood. Here we carried out a mammalian two-hybrid screen and identified multiple transcriptional regulators potentially interacting with TET2. The SMAD nuclear interacting protein 1 (SNIP1) physically interacts with TET2 and bridges TET2 to bind several transcription factors, including c-MYC. SNIP1 recruits TET2 to the promoters of c-MYC target genes, including those involved in DNA damage response and cell viability. TET2 protects cells from DNA damage-induced apoptosis dependending on SNIP1. Our observations uncover a mechanism for targeting TET2 to specific promoters through a ternary interaction with a co-activator and many sequence-specific DNA-binding factors. This study also reveals a TET2-SNIP1-c-MYC pathway in mediating DNA damage response, thereby connecting epigenetic control to maintenance of genome stability.
Assuntos
Dano ao DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Biocatálise/efeitos dos fármacos , Linhagem Celular Tumoral , Cisplatino/farmacologia , Quebras de DNA de Cadeia Dupla , Proteínas de Ligação a DNA/química , Dioxigenases , Regulação da Expressão Gênica/efeitos dos fármacos , Células HEK293 , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , Ligação Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas/química , Proteínas de Ligação a RNA , Transcrição Gênica/efeitos dos fármacosRESUMO
Fatty acid synthase (FASN) is the terminal enzyme in de novo lipogenesis and plays a key role in cell proliferation. Pharmacologic inhibitors of FASN are being evaluated in clinical trials for treatment of cancer, obesity, and other diseases. Here, we report a previously unknown mechanism of FASN regulation involving its acetylation by KAT8 and its deacetylation by HDAC3. FASN acetylation promoted its degradation via the ubiquitin-proteasome pathway. FASN acetylation enhanced its association with the E3 ubiquitin ligase TRIM21. Acetylation destabilized FASN and resulted in decreased de novo lipogenesis and tumor cell growth. FASN acetylation was frequently reduced in human hepatocellular carcinoma samples, which correlated with increased HDAC3 expression and FASN protein levels. Our results suggest opportunities to target FASN acetylation as an anticancer strategy. Cancer Res; 76(23); 6924-36. ©2016 AACR.
