RESUMEN
The downregulation of melatonin receptor 1A (MTNR1A) is associated with a range of pathological conditions, including membranous nephropathy. Knowledge of the mechanism underlying MTNR1A expression has been limited to the transcriptional regulation level. Here, RNA interference screening in human kidney cells revealed that heterogeneous nuclear ribonucleoprotein L (hnRNPL) upregulated MTNR1A RNA post-transcriptionally. hnRNPL knockdown or overexpression led to increased or decreased levels of cyclic adenosine monophosphate-responsive element-binding protein phosphorylation, respectively. Molecular studies showed that cytoplasmic hnRNPL exerts a stabilizing effect on the MTNR1A transcript through CA-repeat elements in its coding region. Further studies revealed that the interaction between hnRNPL and MTNR1A serves to protect MNTR1A RNA degradation by the exosome component 10 protein. MTNR1A, but not hnRNPL, displays a diurnal rhythm in mouse kidneys. Enhanced levels of MTNR1A recorded at midnight correlated with robust binding activity between cytoplasmic hnRNPL and the MTNR1A transcript. Both hnRNPL and MTNR1A were decreased in the cytoplasm of tubular epithelial cells from experimental membranous nephropathy kidneys, supporting their clinical relevance. Collectively, our data identified cytoplasmic hnRNPL as a novel player in the upregulation of MTNR1A expression in renal tubular epithelial cells, and as a potential therapeutic target.
Asunto(s)
Citoplasma/metabolismo , Ribonucleoproteína Heterogénea-Nuclear Grupo L/metabolismo , Túbulos Renales/metabolismo , Receptor de Melatonina MT1/genética , Animales , Línea Celular , Ritmo Circadiano/genética , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Células Epiteliales/metabolismo , Exorribonucleasas/metabolismo , Complejo Multienzimático de Ribonucleasas del Exosoma/metabolismo , Glomerulonefritis Membranosa/genética , Glomerulonefritis Membranosa/patología , Humanos , Túbulos Renales/patología , Ratones Endogámicos BALB C , Modelos Biológicos , Sistemas de Lectura Abierta/genética , Fosforilación , Estabilidad del ARN/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptor de Melatonina MT1/metabolismo , Secuencias Repetitivas de Ácidos Nucleicos/genética , Regulación hacia Arriba/genéticaRESUMEN
Melatonin is a hormone majorly secreted by the pineal gland and contributes to a various type of physiological functions in mammals. The melatonin production is tightly limited to the AANAT level, yet the most known molecular mechanisms underlying AANAT gene transcription is limited in the pinealocyte. Here, we find that c-Fos and cAMP-response element-binding protein (CREB) decreases and increases the AANAT transcriptional activity in renal tubular epithelial cell, respectively. Notably, c-Fos knockdown significantly upregulates melatonin levels in renal tubular cells. Functional results indicate that AANAT expression is decreased by c-Fos and resulted in enhancement of cell damage in albumin-injury cell model. We further find an inverse correlation between c-Fos and AANAT levels in renal tubular cells from experimental membranous nephropathy (MN) samples and clinical MN specimens. Our finding provides the molecular basis of c-Fos in transcriptionally downregulating expression of AANAT and melatonin, and elucidate the protective role of AANAT in preventing renal tubular cells death in albumin-injury cell model and MN progression.
Asunto(s)
N-Acetiltransferasa de Arilalquilamina/genética , Regulación hacia Abajo , Células Epiteliales/metabolismo , Glomerulonefritis Membranosa/genética , Proteínas Proto-Oncogénicas c-fos/genética , Animales , N-Acetiltransferasa de Arilalquilamina/metabolismo , Línea Celular , Células Cultivadas , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/genética , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Glomerulonefritis Membranosa/metabolismo , Glomerulonefritis Membranosa/patología , Células HEK293 , Humanos , Túbulos Renales/citología , Melatonina/metabolismo , Ratones , Proteínas Proto-Oncogénicas c-fos/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Activación TranscripcionalRESUMEN
Membranous nephropathy (MN), a type of glomerular nephritis, is one of the most common causes of nephrotic syndrome in adults. Although it is known that melatonin plays a protective role in MN, the role of melatonin receptors in the pathophysiology of MN is unclear. Using an experimental MN model and clinical MN specimens, we studied melatonin receptor expression and found that melatonin receptor 1A (MTNR1A) expression was significantly downregulated in renal tubular epithelial cells. Molecular studies showed that the transcription factor pituitary homeobox-1 (PITX1) promoted MTNR1A expression via direct binding to its promoter. Treatment of a human tubular cell line with albumin to induce injury resulted in the stable reduction in MTNR1A and PITX1 expression. PITX1 levels were significantly downregulated in tubular epithelial cells from mice MN kidneys and MN renal specimens. Knockdown of MTNR1A, PITX1, or cyclic adenosine monophosphate-responsive element-binding protein (CREB) decreased E-cadherin (CDH1) expression, but upregulated Per2 and α-smooth muscle actin (αSMA) expression. Blockade of the MTNR1A receptor with luzindole in MN mice further impaired renal function; this was accompanied by CDH1 downregulation and Per2 and αSMA upregulation. Together, our results suggest that in injured tissue, decreased PITX1 expression at the MTNR1A promoter regions leads to decreased levels of MTNR1A in renal tubular epithelial cells, which increases the future risk of MN.
Asunto(s)
Células Epiteliales/metabolismo , Glomerulonefritis Membranosa/metabolismo , Túbulos Renales/metabolismo , Factores de Transcripción Paired Box/metabolismo , Receptor de Melatonina MT1/metabolismo , Animales , Inmunoprecipitación de Cromatina , Femenino , Regulación de la Expresión Génica/genética , Regulación de la Expresión Génica/fisiología , Glomerulonefritis Membranosa/genética , Inmunohistoquímica , Ratones , Ratones Endogámicos BALB C , Regiones Promotoras Genéticas/genética , Interferencia de ARNRESUMEN
Obesity has become a significant global public health problem. Functional drinks have been an essential direction for obesity prevention research. The present study investigated the preventive effect and safety of winter melon and lotus leaf Tibetan tea (WLTT, a compound tea drink based on Ya'an Tibetan Tea and medicine food homology herbs) on obesity. The rats' hypercaloric high-fat diet (HFD) obesity model was established to evaluate obesity prevention and explored the mechanism through intestinal flora regulation. The results showed that in obese rats with the intervention of WLTT (400, 800, and 1600 mg/kg BW), the body weight, fat accumulation, adipocyte cell size, serum lipid levels, and antioxidant enzyme activity (SOD, GSH-Px, and MDA) were progressively improved. 16S rRNA high-throughput sequencing showed that WLTT could improve intestinal flora disorders due to HFD, which significantly reversed the relative abundance of Firmicutes and the F/B ratio associated with an HFD, and significantly upregulated the relative abundance of Verrucomicrobia. At the genus level, the downregulation of the relative abundance of Akkermansia and unclassified_Lachnospiraceae groups, and the upregulation of the relative abundance of Romboutsia, Ruminococcus, Corynebacteriume, and Saccharibacteria_genera_incertae_sedis groups brought about by the HFD were significantly reversed. The results of the above experiments were compared favorably with those of a parallel experiment with Bi -Sheng -Yuan slimming tea (BSY, a functional drink based on green tea and medicine food homology herbs). Overall, the findings have provided that WLTT can prevent obesity owing to an HFD by regulating intestinal flora and has a good safety profile, and combinations of Tibetan tea and medicine food homology herbs could be a new option for obesity prevention.