TAILIEUCHUNG - Báo cáo khoa học: New human and mouse microRNA genes found by homology search

Conservation of microRNAs (miRNAs) among species suggests that they bear conserved biological functions. However, sequencing of new miRNAs has not always been accompanied by a search for orthologues in other spe-cies. I report herein the results of a systematic search for interspecies ortho-logues of miRNA precursors, leading to the identification of 35 human and 45 mouse new putative miRNA genes. MicroRNA tracks were written to visualize miRNAs in human and mouse genomes on the UCSC Genome Browser | ềFEBS Journal New human and mouse microRNA genes found by homology search Michel J. Weber Laboratoire de Biologie Moleculaire Eucaryote UMR5099 CNRS and Universite PaulSabatier IFR109 Toulouse France Keywords antisense transcript genomic localization human genome microRNA mouse genome mRNA degradation RNA interference Correspondence M. Weber LBME 118 route de Narbonne 31062 Toulouse Cedex France Fax 33 5 61 33 58 86 Tel 33 5 61 33 59 56 E-mail weber@ Received 4 June 2004 revised 24 August 2004 accepted 7 September 2004 doi Conservation of microRNAs miRNAs among species suggests that they bear conserved biological functions. However sequencing of new miRNAs has not always been accompanied by a search for orthologues in other species. I report herein the results of a systematic search for interspecies orthologues of miRNA precursors leading to the identification of 35 human and 45 mouse new putative miRNA genes. MicroRNA tracks were written to visualize miRNAs in human and mouse genomes on the UCSC Genome Browser. Based on their localization miRNA precursors can be excised either from introns or exons of mRNAs. When intronic miRNAs are antisense to the apparent host gene they appear to originate from ill-characterized antisense transcription units. Exonic miRNAs are in general nonprotein-coding poorly conserved genes in sense orientation. In three cases the excision of an miRNA from a protein-coding mRNA might lead to the degradation of the rest of the transcript. Moreover three new examples of miRNAs fully complementary to an mRNA are reported. Among these miR135a might control the stability and or translation of an alternative form of the glycerate kinase mRNA by RNA interference. I also discuss the presence of human miRNAs in introns of paralogous genes and in miRNA clusters. MicroRNAs miRNA are w 22 nucleotide-long RNAs that function in translational repression by base pairing with their target mRNA in a variety of

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