RNA-Binding Protein AUF1 Promotes Myogenesis by Regulating MEF2C Expression Levels

Abstract In recent years, type 2 diabetic osteoporosis has become a research hotspot for the complications of diabetes, but the specific mechanism of its occurrence and development remain unknown. Ferroptosis caused by iron overload is considered to be one of the important cause of type 2 diabetic osteoporosis. Polycytosine RNA-binding protein 1 (PCBP1), an iron ion chaperone, was considered as a protector of ferroptosis. The present study aimed to investigate the existence of ferroptosis and specific role of PCBP1 in the development of type 2 diabetes. Firstly, a Cell Counting Kit-8 assay was used to detect the changes of osteoblast viability under the influence of high glucose (HG) and/or ferroptosis inhibitor given at different concentrations and at different times. In addition, the morphological changes of mitochondria in osteoblasts under high glucose were examined via transmission electron microscopy, and the expression levels of PCBP1, ferritin and the ferroptosis-related protein glutathione peroxidase 4 (GPX4) under the action of high glucose were detected via western blotting. Furthermore, a lentivirus was used to silence and overexpress PCBP1. Western blotting was used to detect the expression of levels of the osteoblast functional proteins osteoprotegerin (OPG) and osteocalcin (OCN), while flow cytometry was used to detect the changes of reactive oxygen species (ROS) levels in each group. Under the action of high glucose, the viability of osteoblasts was significantly decreased and the number of mitochondria undergoing atrophy was significantly increased, PCBP1 and ferritin expression levels were increased and GPX4 expression was decreased. Western blotting results demonstrated that infection of the lentivirus overexpressing PCBP1, increased the expression levels of ferritin, GPX4, OPG and OCN, compared with the high glucose group. The flow cytometry results identified a reduction in ROS, and an opposite result was obtained after silencing PCBP1. In conclusion, it was suggested that PCBP1 may protect osteoblasts and reduce the harm caused by ferroptosis by promoting ferritin expression under a high glucose environment. Moreover, it was indicated that PCBP1 may be a potential therapeutic target for treating type 2 diabetic osteoporosis.

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Abstract 362: Genomewide Assessment of Posttranscriptional Events Orchestrated by Quaking that Determine Monocyte Fate

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.34.suppl_1.362 ◽

2014 ◽

Vol 34 (suppl_1) ◽

Author(s):

Eric P van der Veer

Keyword(s):

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Cellular Adhesion ◽

Growth And Survival ◽

Expression Levels ◽

Protein Levels ◽

Atherosclerotic Lesions ◽

Genome Wide ◽

A Genome

The post-transcriptional events that enable monocytes to home to sites of vascular injury, and subsequently differentiate into macrophages within atherosclerotic lesions are poorly understood. We discovered that the mRNA and protein levels of the RNA-binding protein Quaking (QKI) are augmented in CD14+ myeloid cells extracted from advanced human atherosclerotic plaques (4.2-fold upregulated vs. early lesions; p<0.01). This prompted us to investigate how the RNA-binding properties of QKI could influence monocyte fate. Our approach was to examine, at a genome-wide level, how altering the expression levels of QKI could impact pre-mRNA splicing, expression, and localization upon differentiation of human monocytes into Mf. For this, we employed both array-based gene expression analyses as well as next-generation sequencing techniques (RNA-seq) of THP-1 monocytic cells as well as CD14+ monocytes derived from the peripheral blood of a unique, QKI haploinsufficient subject (with sibling control). Despite low expression levels of QKI in monocytes, the abrogation of QKI in these cells perturbed cellular adhesion and the ensuing establishment of the cytoskeletal architecture. Interestingly, our investigation of post-transcriptional events that are associated with the conversion of the monocyte to a macrophage, uncovered: 1) 536 alternative splicing events (p<0.05) that are directly mediated by binding of QKI proximal to the splice site (QBS)(Fig. 1A); and 2) 1214 differentially expressed genes (minimally +/- 1.5-fold; p<0.05) that indicate that QKI modulates monocyte activation and differentiation by regulating inflammation, cell growth and survival, RNA editing and lipid metabolism via activation of the LXR/RXR pathway (Fig. 1B). Collectively, our data illustrate the post-transcriptional events that drive monocyte to macrophage differentiation, and identify the RNA-binding protein QKI as an orchestrator of this inflammatory response.

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