Y RNA

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Y RNA
RF00019.jpg
Predicted secondary structure and sequence conservation of Y_RNA
Identifiers
Symbol Y_RNA
Alt. Symbols Y1; Y2; Y3; Y5
Rfam RF00019
Other data
RNA type Gene
Domain(s) Eukaryota
SO 0000405

Y RNAs are small non-coding RNAs. They are components of the Ro60 ribonucleoprotein particle[1] which is a target of autoimmune antibodies in patients with systemic lupus erythematosus.[2] They are also necessary for DNA replication through interactions with chromatin and initiation proteins.[3][4]

Structure

These small RNAs are predicted to fold into a conserved stem formed by the RNA's 3' and 5' ends and characterized by a single bulged cytosine, which are the known requirements for Ro binding.[5][6][7]

Function

Two functions have been described for Y RNAs in the literature: As a repressor of Ro60, and as an initiation factor for DNA replication. Mutant human Y RNAs lacking the conserved binding site for Ro60 protein still support DNA replication,[3] indicating that binding to Ro protein and promoting DNA replication are two separable functions of Y RNAs. Although Y RNA-derived small RNAs are similar in size to microRNAs, it has been shown that these Y RNA fragments are not involved in the microRNA pathway.[8]

The Ro autoantigen protein (white) binds the end of a double-stranded Y RNA (red) and a single stranded RNA (blue). (PDB: 1YVP [1]).[5]

Ro60 Inhibition

In its free state, Ro binds to a variety of misfolded RNAs including misfolded 5S rRNAs, and is thought to act as some sort of quality control mechanism.[9] Crystal structures of Ro complexed either with Y RNA or another RNA showed that Ro binds single-stranded 3' ends of RNAs relatively nonspecifically, whereas Y RNA binds specifically at a second site that regulates access of other RNAs.[5] In Deinococcus, free Ro has also been shown to function in 23S rRNA maturation.[10] In Deinococcus, mutants lacking Y RNA are viable, and Y RNA appears to be unstable except when complexed with Ro.[10]

DNA replication initiation

Human Y RNAs are functionally required for DNA replication.[3] Biochemical fractionation and reconstitution experiments have established a functional requirement of human Y RNAs for chromosomal DNA replication in isolated vertebrate cell nuclei in vitro[3] and specific degradation of human Y RNAs inhibits DNA replication in vitro, and in intact cells in vivo.[3] Y RNA function is thought to be mediated via interactions with chromatin and initiation proteins (including the origin recognition complex)[4]

In human pathology

Y RNAs are overexpressed in some human tumours and required for cell proliferation[11] and small, microRNA-sized breakdown products may be involved in autoimmunity and other pathological conditions.[12]

Species distribution

Presumptive Y RNA and Ro protein homologs have been found in eukaryotes and bacteria.[6][13] Humans appear to have four Y RNAs, named hY1, hY3, hY4 and hY5[13] and also a large number of pseudogenes. C. elegans has one, named CeY RNA and a large number of sbRNAs that are postulated to also be Y RNA homologues.[14][15] The radiation-resistant bacterium Deinococcus radiodurans encodes a homolog of Ro called rsr ("Ro sixty related"), and at least four small RNAs accumulate in Deinococcus under conditions where rsr expression is induced (UV irradiation); one of these RNAs appears to be a Y RNA homolog.[16]

References

  1. ↑ Y RNAs: recent developments. Adam E. Hall, Carly Turnbull, Tamas Dalmay. Biomolecular Concepts. 2013 January; 4(2):103-110. doi:10.1515/bmc-2012-0050.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 5.2 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Biogenesis of Y RNA-derived small RNAs is independent of the microRNA pathway. Francisco Esteban Nicolas, Adam E. Hall, Tibor Csorba, Carly Turnbull, Tamas Dalmay. FEBS Letters. 2012 April; 586(8):1226-1230. doi:10.1016/j.febslet.2012.03.026.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Are the Ro RNP-associated Y RNAs concealing microRNAs? Y RNA-derived miRNAs may be involved in autoimmunity. Verhagen AP, Pruijn GJ. Bioessays. 2011 Sep;33(9):674-82. doi:10.1002/bies.201100048.
  13. ↑ 13.0 13.1 Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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