ABSTRACT
Interstitial pulmonary fibrosis (IPF) is a progressive disease of diverse etiology manifesting with proliferation of lung fibroblasts and accumulation of extracellular matrix deposition in pulmonary interstitium. Recent studies show aberrant expression of mRNAs and microRNAs (miRNAs) in human embryonic pulmonary fibroblasts (HEPFs). In this study, we investigated effects of the YY1/HSF1/miR-214/THY1 axis on the functions of HEPFs and IPF. Loss- and gain-of-function tests were conducted to identify roles of YY1, HSF1, miR-214, and THY1 in IPF. As determined by RT-qPCR or western blot assay, silencing YY1 down-regulated HSF1 expression and attenuated the expression of pro-proliferative and fibrosis markers in HEPFs. Meanwhile, viability of HEPFs was impeded by YY1 knockdown. The binding relationship between miR-214 and THY1 was verified using dual-luciferase reporter assay. In HEPFs, down-regulation of HSF1 reduced miR-214 expression to repress proliferation and fibrogenic transformation of HEPFs, while inhibition of miR-214 expression could restrain the fibrogenic transformation property of HEPFs by up-regulating THY1. Subsequently, IPF model in mice was induced by bleomycin treatment. These animal experiments validated the protective effects of YY1 knockdown against IPF-induced lung pathological manifestations, which could be reversed by THY1 knockdown. Our study demonstrates the important involvement of YY1/HSF1/miR-214/THY1 axis in the development of IPF.
Subject(s)
Bleomycin/pharmacology , Heat Shock Transcription Factors/metabolism , Idiopathic Pulmonary Fibrosis/metabolism , MicroRNAs/metabolism , Thy-1 Antigens/metabolism , YY1 Transcription Factor/metabolism , Animals , Cell Proliferation/drug effects , Down-Regulation/drug effects , Extracellular Matrix/metabolism , Fibroblasts/metabolism , Fibroblasts/pathology , Heat Shock Transcription Factors/genetics , Humans , Idiopathic Pulmonary Fibrosis/pathology , Lung/metabolism , Lung/pathology , Mice , Mice, Inbred C57BL , MicroRNAs/genetics , Signal Transduction , Thy-1 Antigens/genetics , Up-Regulation/drug effects , YY1 Transcription Factor/geneticsABSTRACT
Heat shock transcription factors (Hsfs) are involved in multiple aspects of stress response and plant growth. However, their role during male gametophyte development is largely unknown, although the generative phase is the most sensitive and critical period in the plant life cycle. Based on a wide screen of T-DNA mutant lines, we identified the atren1 mutation (restricted to nucleolus1) in early male gametophytic gene At1g77570, which has the closest homology to HSFA5 gene, the member of a heat shock transcription factor (HSF) gene family. The mutation causes multiple defects in male gametophyte development in both structure and function. Because the mutation disrupts an early acting (AtREN1) gene, these pollen phenotype abnormalities appear from bicellular pollen stage to pollen maturation. Moreover, the consequent progamic phase is compromised as well as documented by pollen germination defects and limited transmission via male gametophyte. In addition, atren1/- plants are defective in heat stress (HS) response and produce notably higher proportion of aberrant pollen grains. AtREN1 protein is targeted specifically to the nucleolus that, together with the increased size of the nucleolus in atren1 pollen, suggests that it is likely to be involved in ribosomal RNA biogenesis or other nucleolar functions.