MicroRNA (miRNA) biogenesis proceeds from a primary transcript (pri-miRNA) through the pre-miRNA into the mature miRNA. Here, we identify a role of the Caenorhabditis elegans nuclear export receptor XPO-1 and the cap-binding proteins CBP-20/NCBP-2 and CBP-80/NCBP-1 in this process. The RNA-mediated interference of any of these genes causes retarded heterochronic phenotypes similar to those obse...

RNase III Drosha initiates microRNA (miRNA) maturation by cleaving a primary miRNA transcript and releasing a pre-miRNA with a 2 nt 3' overhang. Dicer recognizes the 2 nt 3' overhang structure to selectively process pre-miRNAs. Here, we find that, unlike prototypic pre-miRNAs (group I), group II pre-miRNAs acquire a shorter (1 nt) 3' overhang from Drosha processing and therefore require a 3'-en...

Objective: To explore the influence of RNA interference targeting Rab5a on proliferation and invasion of breast cancer cells, MCF-7, in vitro and provide a new direction for breast cancer gene therapy. Method: Four miRNA interference vectors targeting Rab5a were designed, constructed, and transfected into breast cancer cell line MCF-7. RT-PCR and Western Blots were used to select the most effic...

Many chemotherapy regiments are successfully used to treat breast cancer; however, often breast cancer cells develop drug resistance that usually leads to a relapse and worsening of prognosis. We have shown recently that epigenetic changes such as DNA methylation and histone modifications play an important role in breast cancer cell resistance to chemotherapeutic agents. Another mechanism of ge...

MicroRNAs (miRNAs) govern an expanding number of biological and disease processes. Understanding the mechanisms by which the miRNA pathway is regulated, therefore, represents an important area of investigation. We determined that the human miRNA-generating complex is comprised of Dicer and phospho-TRBP isoforms. Phosphorylation of TRBP is mediated by the mitogen-activated protein kinase (MAPK) ...

HMGA2, a high-mobility group protein, is oncogenic in a variety of tumors, including benign mesenchymal tumors and lung cancers. Knockdown of Dicer in HeLa cells revealed that the HMGA2 gene is transcriptionally active, but its mRNA is destabilized in the cytoplasm through the microRNA (miRNA) pathway. HMGA2 was derepressed upon inhibition of let-7 in cells with high levels of the miRNA. Ectopi...

RAS oncogenes are master regulators of cancers. Somatic mutation in KRAS, HRAS and NRAS genes account for approximately 30% of human cancers. KRAS is the most frequently mutated isoform in RAS-driven cancers. Brain cancers are RAS-driven cancers despite have no RAS mutation or amplification and its pivotal role in brain tumorigenesis has been well documented. Indeed, it’s generally accepted tha...