Alternative titles; symbols
HGNC Approved Gene Symbol: MIR522
Cytogenetic location: 19q13.42 Genomic coordinates (GRCh38): 19:53,751,211-53,751,297 (from NCBI)
MicroRNAs (miRNAs) are noncoding RNAs of about 22 nucleotides that suppress translation of target genes by binding to their mRNAs. MIR522 is part of a primate-specific miRNA cluster on human chromosome 19, termed C19MC. Members of C19MC are expressed specifically in placenta (Bentwich et al., 2005). C19MC is regulated by genomic imprinting, with only the paternally inherited allele expressed (Noguer-Dance et al., 2010).
By combining bioinformatic and microarray analyses with sequence-directed cloning, Bentwich et al. (2005) cloned 43 miRNAs from an miRNA cluster on human chromosome 19, including MIR522. Although miRNAs of the cluster are highly similar, they collectively generate 16 distinct seed sequences. All miRNAs in the cluster are specifically expressed in placenta. Homology analysis showed that the cluster as a whole is conserved only in chimpanzee and possibly rhesus monkey, and the authors found that no individual miRNAs share homology with nonprimate genomes. Further analysis suggested that the cluster evolved through duplication and mutational events unique to primates.
Bortolin-Cavaille et al. (2009) determined that C19MC miRNAs, including MIR522, are processed from introns of large RNA polymerase II (see 180660)-dependent noncoding transcripts expressed mainly, if not exclusively, in placenta. The authors collectively termed these noncoding transcripts 'C19MC host gene,' or C19MC-HG. They confirmed that C19MC-HG transcripts are processed by DGCR8 (609030)-Drosha (608828) to produce miRNAs.
Imprinting of C19MC
Noguer-Dance et al. (2010) found that C19MC is regulated by genomic imprinting, with only the paternally inherited allele expressed in placenta. DNA methylation profiling revealed a differentially methylated region, termed C19MC-DMR1, overlapping an upstream CpG-rich promoter region associated with short tandem repeats. Further analysis showed that the promoter region acquires a maternal-specific methylation imprint in oocytes and generates a complex population of large, compartmentalized noncoding RNAs at C19MC transcription sites. Transcription occurs adjacent to, but not within, a nuclear Alu-rich domain. The authors noted that C19MC maps near another imprinted gene, ZNF331 (606043), suggesting that this region of chromosome 19 may define a large imprinted region specific to primates.
Bentwich et al. (2005) identified MIR522 within an miRNA gene cluster, C19MC, on chromosome 19q13.42. Bortolin-Cavaille et al. (2009) stated that C19MC contains 46 tandemly repeated miRNA genes and spans about 100 kb.
Bentwich, I., Avniel, A., Karov, Y., Aharonov, R., Gilad, S., Barad, O., Barzilai, A., Einat, P., Einav, U., Meiri, E., Sharon, E., Spector, Y., Bentwich, Z. Identification of hundreds of conserved and nonconserved human microRNAs. Nature Genet. 37: 766-770, 2005. [PubMed: 15965474] [Full Text: https://doi.org/10.1038/ng1590]
Bortolin-Cavaille, M.-L., Dance, M., Weber, M., Cavaille, J. C19MC microRNAs are processed from introns of large Pol-II, non-protein-coding transcripts. Nucleic Acids Res. 37: 3464-3473, 2009. [PubMed: 19339516] [Full Text: https://doi.org/10.1093/nar/gkp205]
Noguer-Dance, M., Abu-Amero, S., Al-Khtib, M., Lefevre, A., Coullin, P., Moore, G. E., Cavaille, J. The primate-specific microRNA gene cluster (C19MC) is imprinted in the placenta. Hum. Molec. Genet. 19: 3566-3582, 2010. [PubMed: 20610438] [Full Text: https://doi.org/10.1093/hmg/ddq272]