microRNA-196a Overexpression Inhibits Apoptosis in Hemin-Induced K562 Cells

Insight into microRNAs' involvement in hematopoiesis: current standing point of findings

Hematopoiesis is a complex process in which hematopoietic stem cells are differentiated into all mature blood cells (red blood cells, white blood cells, and platelets). Different microRNAs (miRNAs) involve in several steps of this process. Indeed, miRNAs are small single-stranded non-coding RNA molecules, which control gene expression by translational inhibition and mRNA destabilization. Previous studies have revealed that increased or decreased expression of some of these miRNAs by targeting several proto-oncogenes could inhibit or stimulate the myeloid and erythroid lineage commitment, proliferation, and differentiation. During the last decades, the development of molecular and bioinformatics techniques has led to a comprehensive understanding of the role of various miRNAs in hematopoiesis. The critical roles of miRNAs in cell processes such as the cell cycle, apoptosis, and differentiation have been confirmed as well. However, the main contribution of some miRNAs is still unclear. Therefore, it seems undeniable that future studies are required to focus on miRNA activities during various hematopoietic stages and hematological malignancy.

Post-transcriptional regulation of erythropoiesis

Erythropoiesis is a complex, precise, and lifelong process that is essential for maintaining normal body functions. Its strict regulation is necessary to prevent a variety of blood diseases. Normal erythropoiesis is precisely regulated by an intricate network that involves transcription levels, signal transduction, and various epigenetic modifications. In recent years, research on post-transcriptional levels in erythropoiesis has expanded significantly. The dynamic regulation of splicing transitions is responsible for changes in protein isoform expression that add new functions beneficial for erythropoiesis. RNA-binding proteins adapt the translation of transcripts to the protein requirements of the cell, yielding mRNA with dynamic translation efficiency. Noncoding RNAs, such as microRNAs and lncRNAs, are indispensable for changing the translational efficiency and/or stability of targeted mRNAs to maintain the normal expression of genes related to erythropoiesis. N6-methyladenosine-dependent regulation of mRNA translation plays an important role in maintaining the expression programs of erythroid-related genes and promoting erythroid lineage determination. This review aims to describe our current understanding of the role of post-transcriptional regulation in erythropoiesis and erythroid-associated diseases, and to shed light on the physiological and pathological implications of the post-transcriptional regulation machinery in erythropoiesis. These may help to further enrich our understanding of the regulatory network of erythropoiesis and provide new strategies for the diagnosis and treatment of erythroid-related diseases.

Knockdown of lncRNA HOXA-AS3 Suppresses the Progression of Atherosclerosis via Sponging miR-455-5p

Background

Atherosclerosis can lead to multiple cardiovascular diseases, especially myocardial infarction. Long noncoding RNAs (lncRNAs) are involved in multiple diseases, including atherosclerosis. LncRNA HOXA-AS3 was found to be notably upregulated in atherosclerosis. However, the biological function of HOXA-AS3 during the occurrence and development of atherosclerosis remains unclear.

Materials and Methods

Human vascular endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (oxLDL) to mimic atherosclerosis in vitro. Gene and protein expressions in HUVECs were detected by RT-qPCR and Western blot, respectively. Cell proliferation was tested by CCK-8 and Ki67 staining. Cell apoptosis and cycle were measured by flow cytometry. Additionally, the correlation between HOXA-AS3 and miR-455-5p was confirmed by dual luciferase report assay and RNA pull-down. Finally, in vivo model of atherosclerosis was established to confirm the function of HOXA-AS3 during the development of atherosclerosis in vivo.

Results

LncRNA HOXA-AS3 was upregulated in oxLDL-treated HUVECs. In addition, oxLDL-induced growth inhibition of HUVECs was significantly reversed by knockdown of HOXA-AS3. Consistently, oxLDL notably induced G1 arrest in HUVECs, while this phenomenon was greatly reversed by HOXA-AS3 siRNA. Furthermore, downregulation of HOXA-AS3 notably inhibited the progression of atherosclerosis through mediation of miR-455-5p/p27 Kip1 axis. Besides, silencing of HOXA-AS3 notably relieved the symptom of atherosclerosis in vivo.

Conclusion

Downregulation of HOXA-AS3 significantly suppressed the progression of atherosclerosis via regulating miR-455-5p/p27 Kip1 axis. Thus, HOXA-AS3 might serve as a potential target for the treatment of atherosclerosis.