RESUMO
The liver plays a central role in metabolism, protein synthesis and detoxification. It possesses unique regenerative capacity upon injury. While many factors regulating cellular proliferation during liver repair have been identified, the mechanisms by which the injured liver maintains vital functions prior to tissue recovery are unknown. Here, we identify a new phase of functional compensation following acute liver injury that occurs prior to cellular proliferation. By coupling single-cell RNA-seq with in situ transcriptional analyses in two independent murine liver injury models, we discover adaptive reprogramming to ensure expression of both injury response and core liver function genes dependent on macrophage-derived WNT/ß-catenin signaling. Interestingly, transcriptional compensation is most prominent in non-proliferating cells, clearly delineating two temporally distinct phases of liver recovery. Overall, our work describes a mechanism by which the liver maintains essential physiological functions prior to cellular reconstitution and characterizes macrophage-derived WNT signals required for this compensation.
Assuntos
Regeneração Hepática/fisiologia , Fígado/lesões , Fígado/fisiologia , Acetaminofen/toxicidade , Animais , Ciclo Celular , Proliferação de Células , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Hepatectomia/efeitos adversos , Hepatócitos/citologia , Hepatócitos/metabolismo , Hepatócitos/fisiologia , Fígado/patologia , Regeneração Hepática/genética , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , Via de Sinalização Wnt , beta Catenina/genética , beta Catenina/metabolismoRESUMO
Interactions between regulatory pathways allow organisms to adapt to their environment and respond to stress. One interaction that has been recently identified occurs between the aryl hydrocarbon receptor (AHR) and the nuclear factor erythroid-2 related factor (NRF) family. Each transcription factor regulates numerous downstream genes involved in the cellular response to toxicants and oxidative stress; they are also implicated in normal developmental pathways. The zebrafish model was used to explore the role of AHR regulation of nrf genes during development and in response to toxicant exposure. To determine if AHR1b is responsible for transcriptional regulation of 6 nrf genes during development, a loss-of-function experiment using morpholino-modified oligonucleotides was conducted followed by a chromatin immunoprecipitation study at the beginning of the pharyngula period (24 h postfertilization). The expression of nrf1a was AHR1b dependent and its expression was directly regulated through specific XREs in its cis-promoter. However, nrf1a expression was not altered by exposure to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), a toxicant and prototypic AHR agonist. The expression of nrf1b, nrf2a, and nfe2 was induced by TCDD, and AHR1b directly regulated their expression by binding to cis-XRE promoter elements. Last, nrf2b and nrf3 were neither induced by TCDD nor regulated by AHR1b. These results show that AHR1b transcriptionally regulates nrf genes under toxicant modulation via binding to specific XREs. These data provide a better understanding of how combinatorial molecular signaling potentially protects embryos from embryotoxic events following toxicant exposure.
Assuntos
Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário/genética , Regulação da Expressão Gênica no Desenvolvimento , Fator 2 Relacionado a NF-E2/genética , Receptores de Hidrocarboneto Arílico/genética , Proteínas de Peixe-Zebra/genética , Peixe-Zebra , Animais , Embrião não Mamífero/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/metabolismo , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais , Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento , Proteínas de Peixe-Zebra/metabolismoRESUMO
Pancreatic ductal adenocarcinoma is an aggressive cancer with limited treatment options1. Approximately 10% of cases exhibit familial predisposition, but causative genes are not known in most families2. We perform whole-genome sequence analysis in a family with multiple cases of pancreatic ductal adenocarcinoma and identify a germline truncating mutation in the member of the RAS oncogene family-like 3 (RABL3) gene. Heterozygous rabl3 mutant zebrafish show increased susceptibility to cancer formation. Transcriptomic and mass spectrometry approaches implicate RABL3 in RAS pathway regulation and identify an interaction with RAP1GDS1 (SmgGDS), a chaperone regulating prenylation of RAS GTPases3. Indeed, the truncated mutant RABL3 protein accelerates KRAS prenylation and requires RAS proteins to promote cell proliferation. Finally, evidence in patient cohorts with developmental disorders implicates germline RABL3 mutations in RASopathy syndromes. Our studies identify RABL3 mutations as a target for genetic testing in cancer families and uncover a mechanism for dysregulated RAS activity in development and cancer.