Small interfering RNA mediated transcriptional gene silencing in mammalian cells

Abstract

The present invention relates to transcriptional gene silencing (TGS) in mammalian, including human, cells that is mediated by small interfering RNA (siRNA) molecules. The present invention also relates to a method for directing histone and/or DNA methylation in mammalian, including human, cells. It has been found that siRNAs can be used to direct methylation of DNA in mammalian, including human, cells.

1 . A method of reducing gene expression of a target gene in a cell comprising exposing said cell to an siRNA molecule which is specific for a target sequence in the target gene, wherein the siRNA molecule causes reduced gene expression.  
     
     
         2 . The method of  claim 1 , wherein the siRNA molecule is directed to the promoter region of the gene.  
     
     
         3 . The method of  claim 1 , wherein the siRNA molecule binds to a sequence within about 150 bp of the transcription start site.  
     
     
         4 . The method of  claim 1 , wherein the antisense strand of the siRNA molecule is specific for the target sequence.  
     
     
         5 . The method of  claim 1 , wherein the siRNA molecule increases methylation of histones associated with the target gene.  
     
     
         6 . The method of  claim 5 , wherein the methylation of histones is mediated by Ago1.  
     
     
         7 . The method of  claim 1 , wherein the cell is a mammalian cell.  
     
     
         8 . The method of  claim 7 , wherein the mammalian cell is a human cell.  
     
     
         9 . The method of  claim 1 , wherein said siRNA contains about 18-29 base pairs.  
     
     
         10 . The method of claims  9 , wherein said siRNA contains about 18-21 base pairs.  
     
     
         11 . The method of claims  9 , wherein said siRNA contains about 18-23 base pairs.  
     
     
         12 . The method of claims  9 , wherein said siRNA contains about 19-23 base pairs.  
     
     
         13 . The method of claims  9 , wherein said siRNA contains about 24-28 base pairs.  
     
     
         14 . The method of claims  9 , wherein said siRNA contains about 21-26 base pairs.  
     
     
         15 . The method of  claim 1 , wherein the cell is exposed to the siRNA by introducing into the cell DNA sequences encoding a sense strand and a antisense strand of the siRNA, wherein the siRNA is expressed in the cell.  
     
     
         16 . The method of  claim 15 , wherein the introducing is accomplished using at least one vector.  
     
     
         17 . The method of  claim 16 , wherein the vector is a plasmid vector.  
     
     
         18 . The method of  claim 16 , wherein the vector is a viral vector.  
     
     
         19 . The method of  claim 18 , wherein the viral vector is a retroviral vector, a lentiviral vector, or an adenoviral vector.  
     
     
         20 . The method of  claim 16 , wherein the vector is an adeno-associated vector.  
     
     
         21 . The method of  claim 16 , wherein the introducing takes place in vivo.  
     
     
         22 . The method of  claim 16 , wherein the introducing takes place in vitro.  
     
     
         23 . The method of  claim 16 , wherein the introducing is achieved via transformation, transduction, transfection, or infection.  
     
     
         24 . The method of  claim 16 , wherein said introducing is achieved via a liposome.  
     
     
         25 . The method of  claim 16 , wherein said introducing is achieved via a liposome.