Fine-tuning multiciliated cell differentiation at the post-transcriptional level: contribution of miR-34/449 family members

gga-miR-6634-5p Affects the proliferation and steroid hormone secretion of chicken (Gallus Gallus) granulosa cells by targeting MMP16

MiRNAs are typically reported to play a negative regulatory role in post-transcriptional expression of target genes and are widely involved in a variety of biological processes such as growth, metabolism and reproduction. However, research on the role of miRNAs in the ovulation process of chicken ovaries is still insufficient compared to that in mammals. Here, we investigated the regulatory mechanisms of gga-miR-6634-5p in the growth and steroid hormone secretion of chicken granulosa cells (GCs) by targeting MMP16. We found that gga-miR-6634-5p significantly down-regulated the mRNA levels of proliferation-related genes (CCND1, CDK1, and CDK6), decreased cell viability, the number of EdU-labelled positive cells, and the percentage of S-phase cells, as analysed by quantitative real time PCR (qRT-PCR), cell counting kit-8 (CCK-8), 5-ethynyl-2'deoxyuridine (EdU) and flow cytometry analyses (P < 0.01 or P < 0.05). qRT-PCR and enzyme-linked immunosorbent assay (ELISA) results demonstrated that gga-miR-6634-5p up-regulated the expression of steroid synthesis-related genes (CYP19A1, 3β-HSD, StAR and FSHR) (P < 0.01 or P < 0.05), as well as the secretion of estradiol (E2) and progesterone (P4) (P < 0.01 or P < 0.05). Furthermore, we found that MMP16 protein and gene expression can be down-regulated by gga-miR-6634-5p and demonstrated that MMP16 is a target gene of gga-miR-6634-5p by dual luciferase reporter assay (P < 0.05). In addition, we found that MMP16 stimulated the proliferation of GCs, significantly inhibited the expression of steroid synthesis related genes (CYP19A1, StAR, 3β-HSD and FSHR), and decreased the secretion of E2 and P4 (P < 0.01 or P < 0.05), which was consistent with the inhibitory effect of gga-miR-6634-5p. It was further found by functional enrichment analysis, qRT-PCR, western blot (WB) and ELISA that MMP16 may play a regulatory role in GCs proliferation as well as steroid hormone secretion through the mTOR signaling pathway and PPAR signaling pathway. Therefore, this study demonstrates that gga-miR-6634-5p modulates the proliferation of chicken GCs and the secretion of steroid hormones by targeting MMP16, which may contribute to a better understanding of the functional mechanisms of miRNAs in the ovarian development of laying hens.

Using Zebrafish to Study Multiciliated Cell Development and Disease States

Multiciliated cells (MCCs) serve many important functions, including fluid propulsion and chemo- and mechanosensing. Diseases ranging from rare conditions to the recent COVID-19 global health pandemic have been linked to MCC defects. In recent years, the zebrafish has emerged as a model to investigate the biology of MCCs. Here, we review the major events in MCC formation including centriole biogenesis and basal body docking. Then, we discuss studies on the role of MCCs in diseases of the brain, respiratory, kidney and reproductive systems, as well as recent findings about the link between MCCs and SARS-CoV-2. Next, we explore why the zebrafish is a useful model to study MCCs and provide a comprehensive overview of previous studies of genetic components essential for MCC development and motility across three major tissues in the zebrafish: the pronephros, brain ependymal cells and nasal placode. Taken together, here we provide a cohesive summary of MCC research using the zebrafish and its future potential for expanding our understanding of MCC-related disease states.

Genetic mechanisms of multiciliated cell development: from fate choice to differentiation in zebrafish and other models

Multiciliated cells (MCCS) form bundles of cilia and their activities are essential for the proper development and physiology of many organ systems. Not surprisingly, defects in MCCs have profound consequences and are associated with numerous disease states. Here, we discuss the current understanding of MCC formation, with a special focus on the genetic and molecular mechanisms of MCC fate choice and differentiation. Furthermore, we cast a spotlight on the use of zebrafish to study MCC ontogeny and several recent advances made in understanding MCCs using this vertebrate model to delineate mechanisms of MCC emergence in the developing kidney.

Unraveling the role of Xist RNA in cardiovascular pathogenesis

Understanding the molecular pathways behind cardiovascular illnesses is crucial due to the enormous worldwide health burden they impose. New insights into the role played by Xist (X-inactive specific transcript) RNA in the onset and progression of cardiovascular diseases have emerged from recent studies. Since its discovery, Xist RNA has been known for its role in X chromosome inactivation during embryogenesis; however, new data suggest that its function extends well beyond the control of sex chromosomes. The regulatory roles of Xist RNA are extensive, encompassing epigenetic changes, gene expression, cellular identity, and sex chromosomal inactivation. There is potential for the involvement of this complex regulatory web in a wide range of illnesses, including cardiovascular problems. Atherosclerosis, hypertrophy, and cardiac fibrosis are all conditions linked to dysregulation of Xist RNA expression. Alterations in DNA methylation and histones are two examples of epigenetic changes that Xist RNA orchestrates, leading to modifications in gene expression patterns in different cardiovascular cells. Additionally, Xist RNA has been shown to contribute to the development of cardiovascular illnesses by modulating endothelial dysfunction, inflammation, and oxidative stress responses. New treatment approaches may become feasible with a thorough understanding of the complex function of Xist RNA in cardiovascular diseases. By focusing on Xist RNA and the regulatory network with which it interacts, we may be able to slow the progression of atherosclerosis, cardiac hypertrophy, and fibrosis, thereby opening novel therapeutic options for cardiovascular diseases amenable to precision medicine. This review summarizes the current state of knowledge concerning the impact of Xist RNA in cardiovascular disorders.

miR-449a ameliorates acute rejection after liver transplantation via targeting procollagen-lysine1,2-oxoglutarate5-dioxygenase 1 in macrophages

Acute rejection (AR) is an important factor that leads to poor prognosis after liver transplantation (LT). Macrophage M1-polarization is an important mechanism in AR development. MicroRNAs play vital roles in disease regulation; however, their effects on macrophages and AR remain unclear. In this study, rat models of AR were established following LT, and macrophages and peripheral blood mononuclear cells were isolated from rats and humans, respectively. We found miR-449a expression to be significantly reduced in macrophages and peripheral blood mononuclear cells. Overexpression of miR-449a not only inhibited the M1-polarization of macrophages in vitro but also improved the AR of transplant in vivo. The mechanism involved inhibiting the noncanonical nuclear factor-kappaB (NF-κB) pathway. We identified procollagen-lysine1,2-oxoglutarate5-dioxygenase 1 (PLOD1) as a target gene of miR-449a, which could reverse miR-449a's inhibition of macrophage M1-polarization, amelioration of AR, and inhibition of the NF-κB pathway. Overall, miR-449a inhibited the NF-κB pathway in macrophages through PLOD1 and also inhibited the M1-polarization of macrophages, thus attenuating AR after LT. In conclusion, miR-449a and PLOD1 may be new targets for the prevention and mitigation of AR.

CircEML1 facilitates the steroid synthesis in follicular granulosa cells of chicken through sponging gga-miR-449a to release IGF2BP3 expression

Non-coding RNAs (ncRNAs) induced competing endogenous RNAs (ceRNA) play crucial roles in various biological process by regulating target gene expression. However, the studies of ceRNA networks in the regulation of ovarian ovulation processing of chicken remains deficient compared to that in mammals. Our present study revealed that circEML1 was differential expressed in hen's ovarian tissues at different ages (15 W/20 W/30 W/68 W) and identified as a loop structure from EML1 pre-mRNA, which promoted the expressions of CYP19A1/StAR and E2/P4 secretion in follicular granulosa cells (GCs). Furthermore, circEML1 could serve as a sponge of gga-miR-449a and also found that IGF2BP3 was targeted by gga-miR-449a to co-participate in the steroidogenesis, which possibly act the regulatory role via mTOR/p38MAPK pathways. Meanwhile, in the rescue experiment, gga-miR-449a could reverse the promoting role of circEML1 to IGF2BP3 and steroidogenesis. Eventually, this study suggested that circEML1/gga-miR-449a/IGF2BP3 axis exerted an important role in the steroidogenesis in GCs of chicken.

The Dynamics of miR-449a/c Expression during Uterine Cycles Are Associated with Endometrial Development

The human endometrium is a highly dynamic tissue. Increasing evidence has shown that microRNAs (miRs) play essential roles in human endometrium development. Our previous assay, based on small RNA-sequencing (sRNA-seq) indicated the complexity and dynamics of numerous sequence variants of miRs (isomiRs) that can act together to control genes of functional relevance to the receptive endometrium (RE). Here, we used a greater average depth of sRNA-seq to detect poorly expressed small RNAs. The sequencing data confirmed the up-regulation of miR-449c and uncovered other members of the miR-449 family up-regulated in RE-among them miR-449a, as well as several isoforms of both miR-449a and miR-449c, while the third family member, miR-449b, was not identified. Stem-looped RT-qPCR analysis of miR expression at four-time points of the endometrial cycle verified the increased expression of the miR-449a/c family members in RE, among which the 5' isoform of miR-449c-miR-449c.1 was the most strongly up-regulated. Moreover, we found in a case study that the expression of miR-449c.1 and its precursor correlated with the histological assessment of the endometrial phase and patient age. We believe this study will promote the clinical investigation and application of the miR-449 family in the diagnosis and prognosis of human reproductive diseases.

Investigating the Role of the microRNA-34/449 Family in Male Infertility: A Critical Analysis and Review of the Literature

There is a great body of evidence suggesting that in both humans and animal models the microRNA-34/449 (miR-34/449) family plays a crucial role for normal testicular functionality as well as for successful spermatogenesis, regulating spermatozoa maturation and functionality. This review and critical analysis aims to summarize the potential mechanisms via which miR-34/449 dysregulation could lead to male infertility. Existing data indicate that miR-34/449 family members regulate ciliogenesis in the efferent ductules epithelium. Upon miR-34/449 dysregulation, ciliogenesis in the efferent ductules is significantly impaired, leading to sperm aggregation and agglutination as well as to defective reabsorption of the seminiferous tubular fluids. These events in turn cause obstruction of the efferent ductules and thus accumulation of the tubular fluids resulting to high hydrostatic pressure into the testis. High hydrostatic pressure progressively leads to testicular dysfunction as well as to spermatogenic failure and finally to male infertility, which could range from severe oligoasthenozoospermia to azoospermia. In addition, miR-34/449 family members act as significant regulators of spermatogenesis with an essential role in controlling expression patterns of several spermatogenesis-related proteins. It is demonstrated that these microRNAs are meiotic specific microRNAs as their expression is relatively higher at the initiation of meiotic divisions during spermatogenesis. Moreover, data indicate that these molecules are essential for proper formation as well as for proper function of spermatozoa per se. MicroRNA-34/449 family seems to exert significant anti-oxidant and anti-apoptotic properties and thus contribute to testicular homeostatic regulation. Considering the clinical significance of these microRNAs, data indicate that the altered expression of the miR-34/449 family members is strongly associated with several aspects of male infertility. Most importantly, miR-34/449 levels in spermatozoa, in testicular tissues as well as in seminal plasma seem to be directly associated with severity of male infertility, indicating that these microRNAs could serve as potential sensitive biomarkers for an accurate individualized differential diagnosis, as well as for the assessment of the severity of male factor infertility. In conclusion, dysregulation of miR-34/449 family detrimentally affects male reproductive potential, impairing both testicular functionality as well as spermatogenesis. Future studies are needed to verify these conclusions.