MicroRNAs: Genomics, Biogenesis, Mechanism, and Function

MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.

The functions of animal microRNAs

MicroRNAs are a family of small, non-coding RNAs that regulate gene expression in a sequence-specific manner. The two founding members of the microRNA family were originally identified in Caenorhabditis elegans as genes that were required for the timed regulation of developmental events. Since then, hundreds of microRNAs have been identified in almost all metazoan genomes, including worms, flies, plants and mammals. MicroRNAs have diverse expression patterns and might regulate various developmental and physiological processes. Their discovery adds a new dimension to our understanding of complex gene regulatory networks.

/pdf/micrornas-small-rnas-with-a-big-role-in-gene-regulation-3a05xihg95.pdf

MicroRNAs: small RNAs with a big role in gene regulation

I MicroRNAs (miRNAs) are an abundant class of small non-protein-coding RNAs that function as negative gene regulators. They regulate diverse biological processes, and bioinformatic data indicates that each miRNA can control hundreds of gene targets, underscoring the potential influence of miRNAs on almost every genetic pathway. Recent evidence has shown that miRNA mutations or mis-expression correlate with various human cancers and indicates that miRNAs can function as tumour suppressors and oncogenes. miRNAs have been shown to repress the expression of important cancer-related genes and might prove useful in the diagnosis and treatment of cancer.

Oncomirs : microRNAs with a role in cancer

MicroRNAs (miRNAs) are an abundant class of small non-protein-coding RNAs that function as negative gene regulators They regulate diverse biological processes, and bioinformatic data indicates that each miRNA can control hundreds of gene targets, underscoring the potential influence of miRNAs on almost every genetic pathway Recent evidence has shown that miRNA mutations or mis-expression correlate with various human cancers and indicates that miRNAs can function as tumour suppressors and oncogenes miRNAs have been shown to repress the expression of important cancer-related genes and might prove useful in the diagnosis and treatment of cancer

/pdf/oncomirs-micrornas-with-a-role-in-cancer-4ryo1mpf3s.pdf

Oncomirs — microRNAs with a role in cancer

Temporal regulation of microRNA expression in Drosophila melanogaster mediated by hormonal signals and Broad-Complex gene activity

Ecdysterone induces the transcription of four heat-shock genes in Drosophila S3 cells and imaginal discs.

The expression of the let-7 small regulatory RNA is controlled by ecdysone during metamorphosis in Drosophila melanogaster.

Gene-enzyme variation was examined, electrophoretically, at three non-specific esterase loci in 15 sympatric populations of the prosobranch gastropods: Littorina littorea L. obtusata, and L. saxatilis. Gene frequencies, determined by assuming a correspondence between bands on gels and alleles, revealed marked differences between the species. These differences appear to be correlated with the mechanisms and capabilities for larval disposal in these species.

Gene-enzyme variation in three sympatric species of littorina

Treatment of Schneider's line 3 Drosophila cells with the steroid hormone ecdysterone rapidly stimulated the synthesis and accumulation of the polypeptide previously designated p7 [Berger, E. M., Ireland, R. C. & Wyss, C. (1980) Somatic Cell Genet. 6, 119-129]. In this report, p7 is identified as the 23,000-dalton heat shock polypeptide (hsp23). In addition to hsp23, the synthesis of the low molecular weight heat shock polypeptides hsp22, hsp26, and hsp27 was also stimulated by ecdysterone, although to different extents. Hybridization of a nick-translated genomic clone containing the hsp23 gene to a total RNA blot showed that ecdysterone stimulation of hsp23 synthesis was the result of an increase in the hsp23 RNA content of S3 cells. We detected no effect of the hormone on the synthesis of heat shock polypeptides hsp68, hsp70, and hsp83.

/pdf/synthesis-of-low-molecular-weight-heat-shock-peptides-2b32f9y0k3.pdf

Edward M. Berger

Papers

Temporal regulation of microRNA expression in Drosophila melanogaster mediated by hormonal signals and Broad-Complex gene activity

Ecdysterone induces the transcription of four heat-shock genes in Drosophila S3 cells and imaginal discs.

The expression of the let-7 small regulatory RNA is controlled by ecdysone during metamorphosis in Drosophila melanogaster.

Gene-enzyme variation in three sympatric species of littorina

Synthesis of low molecular weight heat shock peptides stimulated by ecdysterone in a cultured Drosophila cell line