RevCen
Encyclopedia
RevCen is a family of non-coding RNA
found in Schizosaccharomyces
. It is a megastructure containing several siRNA
which use the RNAi
pathway to regulate heterochromatin
formation. The long RNA transcript forms a secondary structure
with several stem-loop
s which are processed by dicer
into siRNA. This siRNA then initiate the formation of heterochromatin at the centromere
s of fission yeast. Northern blot analysis
confirmed the siRNAs were produced from the large RNA structure RevCen in vivo
. As with all siRNAs, the enzyme dicer
is responsible for dissecting dsRNA into the 21nt
strech of double-stranded RNA. Human recombinant dicer enzyme processed the RevCen structure in vitro, though the same activity by yeast Dcr1 has not been confirmed.
This is a different mechanism to that involving the well-understood RITS (RNA-induced initiation of transcriptional gene silencing
) complex. It has been suggested that both mechanisms work together, with the RevCen structure potentially acting as a backup system when Rdp1-generated double-stranded siRNA precursors are lost.
Non-coding RNA
A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...
found in Schizosaccharomyces
Schizosaccharomyces
Schizosaccharomyces is a genus of fission yeasts. The most well-studied species is S. pombe. At present four Schizosaccharomyces species have been described . Like the distantly related Saccharomyces cerevisiae, S. pombe is a significant model organism in the study of eukaryotic cell biology...
. It is a megastructure containing several siRNA
Sírna
Sírna Sáeglach , son of Dian mac Demal, son of Demal mac Rothechtaid, son of Rothechtaid mac Main, was, according to medieval Irish legend and historical tradition, a High King of Ireland...
which use the RNAi
RNAI
RNAI is a non-coding RNA that is an antisense repressor of the replication of some E. coli plasmids, including ColE1. Plasmid replication is usually initiated by RNAII, which acts as a primer by binding to its template DNA. The complementary RNAI binds RNAII prohibiting it from its initiation role...
pathway to regulate heterochromatin
Heterochromatin
Heterochromatin is a tightly packed form of DNA, which comes in different varieties. These varieties lie on a continuum between the two extremes of constitutive and facultative heterochromatin...
formation. The long RNA transcript forms a secondary structure
Secondary structure
In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids...
with several stem-loop
Stem-loop
Stem-loop intramolecular base pairing is a pattern that can occur in single-stranded DNA or, more commonly, in RNA. The structure is also known as a hairpin or hairpin loop. It occurs when two regions of the same strand, usually complementary in nucleotide sequence when read in opposite directions,...
s which are processed by dicer
Dicer
Dicer is an endoribonuclease in the RNase III family that cleaves double-stranded RNA and pre-microRNA into short double-stranded RNA fragments called small interfering RNA about 20-25 nucleotides long, usually with a two-base overhang on the 3' end...
into siRNA. This siRNA then initiate the formation of heterochromatin at the centromere
Centromere
A centromere is a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come closest in contact. It is involved in cell division as the point of mitotic spindle attachment...
s of fission yeast. Northern blot analysis
Northern blot
The northern blot is a technique used in molecular biology research to study gene expression by detection of RNA in a sample. With northern blotting it is possible to observe cellular control over structure and function by determining the particular gene expression levels during differentiation,...
confirmed the siRNAs were produced from the large RNA structure RevCen in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
. As with all siRNAs, the enzyme dicer
Dicer
Dicer is an endoribonuclease in the RNase III family that cleaves double-stranded RNA and pre-microRNA into short double-stranded RNA fragments called small interfering RNA about 20-25 nucleotides long, usually with a two-base overhang on the 3' end...
is responsible for dissecting dsRNA into the 21nt
Nucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
strech of double-stranded RNA. Human recombinant dicer enzyme processed the RevCen structure in vitro, though the same activity by yeast Dcr1 has not been confirmed.
This is a different mechanism to that involving the well-understood RITS (RNA-induced initiation of transcriptional gene silencing
Gene silencing
Gene silencing is a general term describing epigenetic processes of gene regulation. The term gene silencing is generally used to describe the "switching off" of a gene by a mechanism other than genetic modification...
) complex. It has been suggested that both mechanisms work together, with the RevCen structure potentially acting as a backup system when Rdp1-generated double-stranded siRNA precursors are lost.