In
molecular biology, Small nucleolar RNA SNORD113 (also known as C/D box snoRNA 14q(I)) is a
small nucleolar RNA
In molecular biology, Small nucleolar RNAs (snoRNAs) are a class of small RNA molecules that primarily guide chemical modifications of other RNAs, mainly ribosomal RNAs, transfer RNAs and small nuclear RNAs. There are two main classes of snoRNA, t ...
molecule which is located in the
imprinted human 14q32
locus and may play a role in the evolution and/or mechanism of the
epigenetic
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...
imprinting process.
In humans the imprinted domain at 14q32 contains two clusters of tandemly repeated small nucleolar RNAs named 14q(I) and 14q(II) snoRNAs. These two clusters contain 9 and 31 highly related snoRNAs respectively. These two related snoRNAs are known as SNORD113 and SNORD114 respectively in the
HGNC approved
gene symbol nomenclature. The snoRNAs found in each cluster are clearly related and are simply referred to with a 1-9 or 1-31 suffix. All the snoRNAs in these clusters are
intron
An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e. a region inside a gene."The notion of the cistron .e., gene. ...
encoded and are processed from the tissue-specific non-coding human
MEG8 RNA, which lies downstream of the imprinted genes DLK1 and GTL2.
SNORD113 and SNORD114 belong to the
C/D box class of snoRNAs which contain the conserved
sequence motif
In biology, a sequence motif is a nucleotide or amino-acid sequence pattern that is widespread and usually assumed to be related to biological function of the macromolecule. For example, an ''N''-glycosylation site motif can be defined as ''As ...
s known as the C box (UGAUGA) and the D box (CUGA). Most of the members of the box C/D family function in directing site-specific 2'-O-
methylation
In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...
of substrate RNAs.
However, SNORD113 and SNORD114 differ from most C/D box snoRNAs in their expression profiles (which is tissue specific) and the lack of complementarity to
rRNA and
SnRNA. As a result, they are not predicted to guide to 2'O-methylation of a rRNA or snRNA.
Homologues of SNORD113 and SNORD114 are found in the imprinted non-coding mouse transcript Rian where they are again found in tandem array of 9 highly related snoRNAs. These snoRNAs also display tissue specific (brain) expression. C/D box snoRNAs were also identified in the rat non-coding Bsr (brain-specific repetitive) RNA.
Another imprinted human locus 15q11q13 encodes tandemly repeated C/D box snoRNA genes which are expressed only from the paternal
chromosome. Studies of human and mouse model systems have shown that deletion of the 29 copies of the C/D box snoRNA SNORD116 (HBII-85) from this locus has been shown to be the primary cause of
Prader-Willi syndrome.
A possible role for tandemly repeated C/D snoRNA genes in the evolution and/or mechanism of the epigenetic imprinting process has been suggested.
References
External links
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{{Small nucleolar RNA
Small nuclear RNA