Genomic Analysis of MicroRNA Promoters and Their Cis-Acting Elements in Soybean

MicroRNAs （miRNAs） are derived from distinct loci in the genome and play crucial roles in RNA-mediated gene silencing mechanisms that regulate cellular processes during development and stress responses of plants. The miRNAs are approximately 21 nucleotides long and code for the complementary strand to a larger genic mRNA. They are often found within the complementary primary transcript （pri-miRNAs）. In the past few years, a growing number of soybean miRNAs have been discovered, however, little is known about the transcriptional regulation of these miRNAs. In this study, promoters and cis-acting elements of soybean miRNAs were analyzed using the genomic data for the first time. A total of 82 miRNAs were located among 122 loci in genome, some were present as double or multiple copies. Five clusters that included ten miRNAs were found in genome, and only one cluster share the same promoter. A total of 191 promoters from 122 loci of the soybean miRNA sequences were found and further analyzed. The results indicated that the conserved soybean miRNA genes had a greater proportion of promoters than that of non-conserved ones, and the distribution of the transcript start sites （TSSs） and TATA-boxes found had different motif styles between conserved and non-conserved miRNA genes. Furthermore, the cis-acting elements 5＇ of the TSSs were analyzed to obtain potential function and spatiotemporal expression pattern of miRNAs. The data obtained here may lead to the identification of specific sequences upstream of pre-miRNAs and the functional annotation of miRNAs in soybean.

Deregulated miRNA clusters in ovarian cancer:Imperative implications in personalized medicine

Ovarian cancer(OC)is one of the most common and fatal types of gynecological cancer.OC is usually detected at the advanced stages of the disease,making it highly lethal.miRNAs are single-stranded,small non-coding RNAs with an approximate size ranging around 22 nt.Interestingly,a considerable proportion of miRNAs are organized in clusters with miRNA genes placed adjacent to one another,getting transcribed together to result in miRNA clusters(MCs).MCs comprise two or more miRNAs that follow the same orientation during transcription.Abnormal expression of the miRNA cluster has been identified as one of the key drivers in OC.MC exists both as tumor-suppressive and oncogenic clusters and has a significant role in OC pathogenesis by facilitating cancer cells to acquire various hallmarks.The present review summarizes the regulation and biological function of MCs in OC.The review also highlights the utility of abnormally expressed MCs in the clinical management of OC.