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1.
Hepatology ; 73(2): 606-624, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32329085

RESUMO

BACKGROUND AND AIMS: G protein-coupled receptor (GPR) 55 is a putative cannabinoid receptor, and l-α-lysophosphatidylinositol (LPI) is its only known endogenous ligand. Although GPR55 has been linked to energy homeostasis in different organs, its specific role in lipid metabolism in the liver and its contribution to the pathophysiology of nonalcoholic fatty liver disease (NAFLD) remains unknown. APPROACH AND RESULTS: We measured (1) GPR55 expression in the liver of patients with NAFLD compared with individuals without obesity and without liver disease, as well as animal models with steatosis and nonalcoholic steatohepatitis (NASH), and (2) the effects of LPI and genetic disruption of GPR55 in mice, human hepatocytes, and human hepatic stellate cells. Notably, we found that circulating LPI and liver expression of GPR55 were up-regulated in patients with NASH. LPI induced adenosine monophosphate-activated protein kinase activation of acetyl-coenzyme A carboxylase (ACC) and increased lipid content in human hepatocytes and in the liver of treated mice by inducing de novo lipogenesis and decreasing ß-oxidation. The inhibition of GPR55 and ACCα blocked the effects of LPI, and the in vivo knockdown of GPR55 was sufficient to improve liver damage in mice fed a high-fat diet and in mice fed a methionine-choline-deficient diet. Finally, LPI promoted the initiation of hepatic stellate cell activation by stimulating GPR55 and activation of ACC. CONCLUSIONS: The LPI/GPR55 system plays a role in the development of NAFLD and NASH by activating ACC.


Assuntos
Lisofosfolipídeos/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Obesidade/complicações , Receptores de Canabinoides/metabolismo , Acetil-CoA Carboxilase/antagonistas & inibidores , Acetil-CoA Carboxilase/metabolismo , Adulto , Idoso , Animais , Biópsia , Agonistas de Receptores de Canabinoides/farmacologia , Linhagem Celular , Estudos de Coortes , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Feminino , Técnicas de Silenciamento de Genes , Células Estreladas do Fígado , Hepatócitos , Humanos , Lipogênese/efeitos dos fármacos , Fígado/patologia , Lisofosfolipídeos/sangue , Masculino , Camundongos , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/sangue , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/patologia , Obesidade/sangue , Obesidade/metabolismo , Receptores de Canabinoides/genética , Regulação para Cima
2.
Front Cell Dev Biol ; 8: 630754, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33537318

RESUMO

Ten-eleven translocation-2 (TET2) is a crucial driver of cell fate outcomes in a myriad of biological processes, including embryonic development and tissue homeostasis. TET2 catalyzes the demethylation of 5-methylcytosine on DNA, affecting transcriptional regulation. New exciting research has provided evidence for TET2 catalytic activity in post-transcriptional regulation through RNA hydroxymethylation. Here we review the current understanding of TET2 functions on both DNA and RNA, and the influence of these chemical modifications in normal development and pluripotency contexts, highlighting TET2 versatility in influencing genome regulation and cellular phenotypes.

3.
STAR Protoc ; 1(2)2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32995755

RESUMO

RNA-binding proteins are key regulators of cell identity and function, which underscores the need for unbiased and versatile protocols to identify and characterize novel protein-RNA interactions. Here, we describe a simple and cost-effective in vitro RNA immunoprecipitation (iv-RIP) method to assess the direct or indirect RNA-binding ability of any protein of interest. The versatility of this method relies on the adaptability of the immunoprecipitation conditions and the choice of the RNA, which exponentially broadens the range of potential applications. For complete details on the use and execution of this protocol, please refer to Guallar et al. (2020).


Assuntos
Imunoprecipitação/métodos , Proteínas de Ligação a RNA , RNA , Animais , Camundongos , Ligação Proteica , RNA/análise , RNA/química , RNA/metabolismo , Proteínas de Ligação a RNA/análise , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo
4.
Life Sci Alliance ; 3(5)2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32284354

RESUMO

BMAL1 is essential for the regulation of circadian rhythms in differentiated cells and adult stem cells, but the molecular underpinnings of its function in pluripotent cells, which hold a great potential in regenerative medicine, remain to be addressed. Here, using transient and permanent loss-of-function approaches in mouse embryonic stem cells (ESCs), we reveal that although BMAL1 is dispensable for the maintenance of the pluripotent state, its depletion leads to deregulation of transcriptional programs linked to cell differentiation commitment. We further confirm that depletion of Bmal1 alters the differentiation potential of ESCs in vitro. Mechanistically, we demonstrate that BMAL1 participates in the regulation of energy metabolism maintaining a low mitochondrial function which is associated with pluripotency. Loss-of-function of Bmal1 leads to the deregulation of metabolic gene expression associated with a shift from glycolytic to oxidative metabolism. Our results highlight the important role that BMAL1 plays at the exit of pluripotency in vitro and provide evidence implicating a non-canonical circadian function of BMAL1 in the metabolic control for cell fate determination.


Assuntos
Fatores de Transcrição ARNTL/metabolismo , Células-Tronco Pluripotentes/metabolismo , Fatores de Transcrição ARNTL/fisiologia , Animais , Diferenciação Celular/fisiologia , Ritmo Circadiano/genética , Metabolismo Energético/fisiologia , Expressão Gênica/genética , Glicólise , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Camundongos , Mitocôndrias/genética , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Células-Tronco Pluripotentes/citologia
5.
Cell Stem Cell ; 27(2): 300-314.e11, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32396862

RESUMO

RNA editing of adenosine to inosine (A to I) is catalyzed by ADAR1 and dramatically alters the cellular transcriptome, although its functional roles in somatic cell reprogramming are largely unexplored. Here, we show that loss of ADAR1-mediated A-to-I editing disrupts mesenchymal-to-epithelial transition (MET) during induced pluripotent stem cell (iPSC) reprogramming and impedes acquisition of induced pluripotency. Using chemical and genetic approaches, we show that absence of ADAR1-dependent RNA editing induces aberrant innate immune responses through the double-stranded RNA (dsRNA) sensor MDA5, unleashing endoplasmic reticulum (ER) stress and hindering epithelial fate acquisition. We found that A-to-I editing impedes MDA5 sensing and sequestration of dsRNAs encoding membrane proteins, which promote ER homeostasis by activating the PERK-dependent unfolded protein response pathway to consequently facilitate MET. This study therefore establishes a critical role for ADAR1 and its A-to-I editing activity during cell fate transitions and delineates a key regulatory layer underlying MET to control efficient reprogramming.


Assuntos
Células-Tronco Pluripotentes Induzidas , Edição de RNA , Adenosina Desaminase/genética , Adenosina Desaminase/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Inosina/metabolismo , RNA de Cadeia Dupla
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