RNA interference provides a new approach for elucidation of gene function. It holds the advantages of quickness, convenience, high effect and high specificity. In spite of these, the application of RNA interference technique in studying the mammalian cells and human disease is still in the beginning. In this paper, a review of the development of RNA interference in mammalian cells and human disease is presented.
Animals ; Genes ; physiology ; Genetic Vectors ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics

Pseudogenes, which have long been described as "fossils", play a very important role in eukaryotic genomes. Recently, studies on the so called "junk gene" have attracted more attention. Far from being silent, pseudogenes participate in various biological activities, including being a part in the transcription process, or participating in the formation of small interfering RNA (siRNA) which regulated gene expression by means of the RNA-interference pathway. Recent studies have also shown that pseudogenes regulate tumor suppression through competing for the microRNA (miRNA) with their parent genes. However, a deeper understanding of function analysis of pseudogenes depends on the comprehensive and accurate identification. With the sequencing completion of many genomes and the innovation of bioinformatics tools, efficient and precise identification of pseudogenes have become available in a genome-wide scale. Our review focused particularly on the method of pseudogene identification, the mechanism of its regulatory roles and its potential to be applied in directed evolution. Besides, the promising research direction of pseudogenes was proposed.
Gene Expression Regulation ; Genes, Tumor Suppressor ; physiology ; MicroRNAs ; genetics ; Pseudogenes ; genetics ; physiology ; RNA Interference ; RNA, Small Interfering ; genetics

Animals ; Humans ; RNA Interference ; RNA, Antisense ; genetics ; RNA, Small Interfering ; genetics ; SARS Virus ; genetics ; physiology ; Severe Acute Respiratory Syndrome ; virology

To investigate the inhibitory effect of RNA interference (RNAi) on dengue virus I (DENV-1) replication. Small interfering RNA (siRNA) against the PreM gene of dengue virus was synthesized and transfected into C6/36 cells with liposome, which was then attacked by DENV-1 virus. The antiviral effect of siRNA was evaluated by cytopathic effect (CPE), the cell survival rate measured by MTT, and virus RNA quantified by real-time RT-PCR. The results showed that after 7 days post infection of dengue virus, the transfected C6/36 cells showed less CPE. The cell survival rate of the transfected C6/36 cells increased by 2.26 fold, and the amount of virus RNA in the transfected cells was reduced by about 97.54% as well. These findings indicated that the siRNA could effectively inhibit dengue virus RNA replication, and protect C6/36 cells from viral attack, indicating its potential role in prevention and treatment of dengue fever.
Animals ; Cell Line ; Dengue Virus ; genetics ; physiology ; RNA Interference ; physiology ; RNA, Small Interfering ; genetics ; RNA, Viral ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Virus Replication ; genetics ; physiology

Epigenetic factors play an important role in male infertility though about 60%－65% of the disease is idiopathic and its underlying causes are not yet clear. Many studies have indicated that epigenetic modifications, including DNA methylation, histone tail modifications, chromatin remodeling, and non-coding RNAs, may be involved in idiopathic male infertility. Abnormal methylation is associated with decreased sperm quality and fertility. It is known that 1 881 miRNAs are related to male fertility and such non-coding RNAs as piRNA, IncRNA, and circRNA play a regulating role in male reproduction. This review focuses on the value of epigenetics in the etiology and pathogenesis of male infertility, aiming to provide some evidence for the establishment of some strategies for the treatment and prediction of the disease.
DNA Methylation ; Epigenesis, Genetic ; Fertility ; Humans ; Infertility, Male ; genetics ; Male ; MicroRNAs ; physiology ; RNA, Small Interfering ; Spermatozoa

OBJECTIVETo observe the effect of small interfering RNA (siRNA)-induced MAPK p42 silencing on the survival of HeLa cells.

METHODSTwo siRNAs targeting at the MAPK p42 gene and one random siRNA were synthesized respectively by Silencer siRNA Construction Kit and transfected into HeLa cells by Lipofectamin 2000. The expression of p42(MAPK) in the transfected HeLa cells was analyzed by Western blotting and immunohistochemistry, and the morphology of cells were observed with electron microscope. TUNEL assay and Annexin V/PI staining were employed for detecting the cell apoptosis.

RESULTSThe expression of p42(MAPK) in the HeLa cells was remarkably suppressed after transfection with the two siRNAs, reduced by about 2.5 and 3.2 folds respectively in comparison with the negative control. Chromatin margination in the cell nuclei were observed in the transfected cells, and TUNEL assay and Annexin V/PI staining further confirmed the occurrence of cell apoptosis.

CONCLUSIONIn vitro MAPK p42 siRNA-1 and siRNA-2 transfection can specifically silence the gene expression and induce apoptosis of HeLa cells.

Apoptosis ; physiology ; Gene Silencing ; physiology ; HeLa Cells ; Humans ; Mitogen-Activated Protein Kinase 1 ; biosynthesis ; genetics ; RNA, Small Interfering ; genetics ; Transfection

The 21-24 nucleotides small RNA that generated from double strands RNA can trigger two types of epigenetic gene silencing in plants. One is Post-Transcriptional Gene Silencing (PTGS), characterized by cleavage of homologous mRNA in cytoplasm. Transcriptional Gene Silencing (TGS) is another one, in which transcription inhibition is obtained through small RNA-directed DNA methylation of homologous promoter region. Here we summarized the relationship and differences between PTGS and TGS, the current achievement in the study of RNA silencing spreading, as well as the discrepancy of exogenous and endogenous gene silencing, and discussed the underlying reasons in the end.
DNA Methylation ; genetics ; Epigenesis, Genetic ; physiology ; Genome, Plant ; genetics ; Plant Immunity ; genetics ; RNA Interference ; RNA, Plant ; genetics ; RNA, Small Interfering ; genetics ; Transcription, Genetic ; genetics

This study was aimed to examine the effect of TREK-1 silencing on the function of astrocytes. Three 21-nucleotide small interfering RNA (siRNA) duplexes (siT1, siT2, siT3) targeting TREK-1 were constructed. Cy3-labeled dsRNA oligmers were used to determine the transfection efficiency in cultured astrocytes. TREK-1-specific siRNA duplexes (siT1, siT2, siT3) at the optimal concentration were transfected into cultured astrocytes, and the most efficient siRNA was identified by the method of immunocytochemical staining and Western blotting. The proliferation of astrocytes tranfected with TREK-1-targeting siRNA under hypoxia condition was measured by fluorescence-activated cell sorting (FACS). The results showed that TREK-1 was expressed in cultured astrocytes. The dsRNA oligmers targeting TREK-1 could be transfected efficiently in cultured astrocytes and down-regulate the expression of TREK-1 in astrocytes. Moreover, the down-regulation of TREK-1 in astrocytes contributed to the proliferation of astrocytes under hypoxia condition as determined by cell cycle analysis. It was concluded that siRNA is a powerful technique that can be used to knockdown the expression of TREK-1 in astrocytes, which helps further investigate the function of TREK-1 channel in astrocytes under physicological and pathological condition.
Animals ; Astrocytes ; physiology ; Cells, Cultured ; Gene Silencing ; physiology ; Potassium Channels ; Potassium Channels, Tandem Pore Domain ; genetics ; RNA Interference ; physiology ; RNA, Small Interfering ; genetics ; Rats

Hepacivirus ; genetics ; Hepatitis B virus ; genetics ; Hepatitis B, Chronic ; therapy ; Hepatitis C ; therapy ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; RNA, Viral ; physiology ; Virus Replication ; genetics

BACKGROUNDRNA interference (RNAi) is a potential cure for amyotrophic lateral sclerosis (ALS) caused by dominant, gain-of-function superoxide dismutase 1 (SOD1) mutations. The success of such therapy relies on the functional small interfering RNAs (siRNAs) that can effectively deliver RNAi. This study aimed to design the functional siRNAs targeting ALS-associated mutant alleles.

METHODSA modified dual luciferase system containing human SOD1 mRNA target was established to quantify siRNA efficacy. Coupled with validated siRNAs identified in the literature, we analyzed the rationale of siRNA design and subsequently developed an asymmetry rule-based strategy for designing siRNA. We then further tested the effectiveness of this design strategy in converting a naturally symmetric siRNA into functional siRNAs with favorable asymmetry for gene silencing of SOD1 alleles.

RESULTSThe efficacies of siRNAs could vary tremendously by one base-pair position change. Functional siRNAs could target the whole span of SOD1 mRNA coding sequence as well as non-coding region. While there is no distinguishable pattern of the distribution of nucleobases in these validated siRNAs, the high percent of GC count at the last two positions of siRNAs (P18 and P19) indicated a strong effect of asymmetry rule. Introducing a mismatch at position 1 of the 5' of antisense strand of siRNA successfully converted the inactive siRNA into functional siRNAs that silence SOD1 with desired efficacy.

CONCLUSIONSAsymmetry rule-based strategy that incorporates a mismatch into siRNA most consistently enhances RNAi efficacy and guarantees producing functional siRNAs that successfully silence ALS-associated SOD1 mutant alleles regardless target positions. This strategy could also be useful to design siRNAs for silencing other disease-associated dominant, gain-of-function mutant genes.

Amyotrophic Lateral Sclerosis ; genetics ; Cell Line ; Humans ; RNA Interference ; physiology ; RNA, Small Interfering ; genetics ; physiology ; Superoxide Dismutase ; genetics ; Superoxide Dismutase-1