RESUMO
MicroRNAs (miRNAs), especially evolutionarily conserved miRNAs play critical roles in regulating various biological process. However, the functions of conserved miRNAs in longevity are still largely unknown. Astragalus polysaccharide (APS) was recently shown to extend lifespan of Caenorhabditis elegans, but its molecular mechanisms have not been fully understood. In the present study, we characterize that microRNA mediated a novel longevity pathway of APS in C. elegans. We found that APS markedly extended the lifespan of C. elegans at the second and the fourth stages. A highly conserved miRNA miR-124 was significantly upregulated in APS-treated C. elegans. Overexpression miR-124 caused the lifespan extension of C. elegans and vice versa, indicating miR-124 regulates the longevity of C. elegans. Using luciferase assay, atf-6 was established as a target gene of miR-124 which acting on three binding sites at atf-6 3'UTR. Consistently, agomir-cel-miR-124 was also shown to inhibit ATF-6 expression in C. elegans. APS-treated C. elegans showed the down-regulation of atf-6 at protein level. Furthermore, the knockdown of atf-6 by RNAi extended the lifespan of C. elegans, indicating atf-6 regulated by miR-124 contributes to lifespan extension. Taken together, miR-124 regulating ATF-6 is a new potential longevity signal pathway, which underlies the lifespan-extending effects of APS in C. elegans.
Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/efeitos dos fármacos , Longevidade/efeitos dos fármacos , MicroRNAs/genética , Polissacarídeos/farmacologia , Fatores de Transcrição/genética , Regiões 3' não Traduzidas/genética , Animais , Astrágalo/química , Sequência de Bases , Sítios de Ligação/genética , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiologia , Proteínas de Caenorhabditis elegans/metabolismo , Regulação da Expressão Gênica , Células HEK293 , Humanos , Longevidade/genética , MicroRNAs/metabolismo , Microscopia de Fluorescência , Mutação , Interferência de RNA , RNA de Helmintos/genética , RNA de Helmintos/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Análise de Sobrevida , Fatores de Transcrição/metabolismoRESUMO
BACKGROUND/AIMS: Abnormal baroreceptor reflex sensitivity (BRS) and elevated plasma neuropeptide Y (NPY) are prevalent in diabetic patients. The present study was conducted to determine whether NPY Y1 receptor (Y1R) and NPY Y2 receptor (Y2R) contribute to the regulatin of BRS in diabetic rats. METHODS: Diabetes mellitus (DM) rats with hyperlipidemia were developed by an emulsion diet enriched with fat, sucrose and fructose followed by streptozocin (STZ). Y1R and Y2R specific antagonists (BIBP 3226 and BIIE 0246) were administered by a mini-osmotic pump. Systolic blood pressure (SBP), heart rate (HR), BRS and heart functions, as well as the plasma NPY and lipid level were measured after treatment for 4 weeks. RESULTS: Both BIBP 3226 and BIIE 0246 treatment reversed the elevated total cholesterol (TC) and low density lipoprotein (LDL-C) level, and reduced high density lipoprotein (HDL-C) level in DM rats. BIIE 0246 may attenuate the increased triglyceride (TG) level in DM rats. In addition, neither BIBP 3226 nor BIIE 0246 treatment produced significant effects on BRS, SBP or HR (P>0.05) in DM rats, even after PE and SNP challenge. However, BIBP 3226 and BIIE 0246 further impaired LVSP, LVEDP, +dp/dtmax and -dp/dtmax. CONCLUSION: This study provided us with the evidence that the inhibition of peripheral Y1R and Y2R did not affect impaired BRS but amplified the deterioration of the compromised cardiac function in STZ-induced DM rats with hyperlipidemia.