Khee Sharon Gwee Sian, Yusof Yasmin Anum Mohd, Makpol Suzana
Department of Biochemistry, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
Oxid Med Cell Longev. 2014;2014:725929. doi: 10.1155/2014/725929. Epub 2014 Jul 14.
Emerging evidences highlight the implication of microRNAs as a posttranscriptional regulator in aging. Several senescence-associated microRNAs (SA-miRNAs) are found to be differentially expressed during cellular senescence. However, the role of dietary compounds on SA-miRNAs remains elusive. This study aimed to elucidate the modulatory role of tocotrienol-rich fraction (TRF) on SA-miRNAs (miR-20a, miR-24, miR-34a, miR-106a, and miR-449a) and established target genes of miR-34a (CCND1, CDK4, and SIRT1) during replicative senescence of human diploid fibroblasts (HDFs). Primary cultures of HDFs at young and senescent were incubated with TRF at 0.5 mg/mL. Taqman microRNA assay showed significant upregulation of miR-24 and miR-34a and downregulation of miR-20a and miR-449a in senescent HDFs (P < 0.05). TRF reduced miR-34a expression in senescent HDFs and increased miR-20a expression in young HDFs and increased miR-449a expression in both young and senescent HDFs. Our results also demonstrated that ectopic expression of miR-34a reduced the expression of CDK4 significantly (P < 0.05). TRF inhibited miR-34a expression thus relieved its inhibition on CDK4 gene expression. No significant change was observed on the expression of CCND1, SIRT1, and miR-34a upstream transcriptional regulator, TP53. In conclusion tocotrienol-rich fraction prevented cellular senescence of human diploid fibroblasts via modulation of SA-miRNAs and target genes expression.
新出现的证据表明，微小RNA作为转录后调节因子在衰老过程中发挥作用。研究发现，几种衰老相关微小RNA（SA - miRNAs）在细胞衰老过程中表达存在差异。然而，膳食化合物对SA - miRNAs的作用仍不明确。本研究旨在阐明富含生育三烯酚组分（TRF）对人二倍体成纤维细胞（HDFs）复制性衰老过程中SA - miRNAs（miR - 20a、miR - 24、miR - 34a、miR - 106a和miR - 449a）以及miR - 34a的既定靶基因（CCND1、CDK4和SIRT1）的调节作用。将年轻和衰老的HDFs原代培养物与0.5mg/mL的TRF一起孵育。Taqman微小RNA检测显示，衰老HDFs中miR - 24和miR - 34a显著上调，miR - 20a和miR - 449a下调（P < 0.05）。TRF降低了衰老HDFs中miR - 34a的表达，增加了年轻HDFs中miR - 20a的表达，并增加了年轻和衰老HDFs中miR - 449a的表达。我们的结果还表明，miR - 34a的异位表达显著降低了CDK4的表达（P < 0.05）。TRF抑制miR - 34a的表达，从而减轻其对CDK4基因表达的抑制。CCND1、SIRT1和miR - 34a上游转录调节因子TP53的表达未观察到显著变化。总之，富含生育三烯酚组分通过调节SA - miRNAs和靶基因表达预防了人二倍体成纤维细胞的细胞衰老。
