molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

, SNORD115 (also known as HBII-52) is a

non-coding RNA A non-coding RNA (ncRNA) is a functional RNA molecule that is not translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important types of non-c ...

(ncRNA) molecule known as 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 ...

which usually functions in guiding the modification of other

s. This type of modifying RNA is usually located in the

nucleolus The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of sig ...

of the eukaryotic cell which is a major site of snRNA biogenesis. HBII-52 refers to the human gene, whereas RBII-52 is used for the rat gene and MBII-52 is used for naming the mouse gene. HBII-52 belongs to the C/D box class of snoRNAs which contain the

conserved sequence In evolutionary biology, conserved sequences are identical or similar sequences in nucleic acids ( DNA and RNA) or proteins across species ( orthologous sequences), or within a genome ( paralogous sequences), or between donor and receptor taxa ...

motifs 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. In the human genome, HBII-52 is encoded in a tandemly repeated array with another C/D box snoRNA, HBII-85 (SNORD116), in the Prader-Willi syndrome (PWS) region of

chromosome 15 Chromosome 15 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 15 spans about 102 million base pairs (the building material of DNA) and represents between 3% and 3.5% of the total DNA ...

. However, a

microdeletion In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is left out during DNA replication. Any number of nucleoti ...

in one family of the snoRNA HBII-52 cluster has excluded it from playing a major role in the disease. HBII-52 is found in 47 tandem near identical copies on human chromosome 15q11-13. This locus is maternally imprinted, meaning that only the paternal copy of the locus is transcribed. HBII-52 is exclusively expressed in the brain but is absent in PWS patients. HBII-52 lacks any significant complementarity with

ribosomal RNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal ...

s, but does have an 18

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules wi ...

region of conserved complementarity to serotonin 2C receptor mRNA. The serotonin 2C receptor is also expressed in the brain. It has been shown that this snoRNA is likely to bind to a silencing element of exon Vb increasing its inclusion and production of a functional spliceform of the serotonin 2C receptor. The chromosomal locus containing the SNORD115 gene cluster has been duplicated in many individuals with autistic traits. A mouse model engineered to have a duplication of the SNORD115 cluster displays autistic-like behaviour. There is evidence that a truncated form of MBII-52 (SNORD115 found in mouse) regulates the alternative splicing of the protein coding genes DPM2,

TAF1 Transcription initiation factor TFIID subunit 1, also known as transcription initiation factor TFIID 250 kDa subunit (TAFII-250) or TBP-associated factor 250 kDa (p250), is a protein that in humans is encoded by the ''TAF1'' gene. Function Init ...

, RALGPS1,

PBRM1 Protein polybromo-1 (PB1) also known as BRG1-associated factor 180 (BAF180) is a protein that in humans is encoded by the ''PBRM1'' gene. Structure and function Component of the SWI/SNF-B (PBAF) chromatin-remodeling complex, which contains at ...

, and

CRHR1 Corticotropin-releasing hormone receptor 1 (CRHR1) is a protein, also known as CRF1, with the latter (CRF1) now being the IUPHAR-recommended name. In humans, CRF1 is encoded by the ''CRHR1'' gene at region 17q21.31, beside micrototubule-associate ...

References

External links

* * {{Small nucleolar RNA Small nuclear RNA