Abstract
BackgroundMicroRNAs (miRNAs) are small non-coding RNAs that have been found to play important roles in silencing target genes and that are involved in the regulation of various normal cellular processes. Until now their implication in the mammary gland biology was suggested by few studies mainly focusing on pathological situations allowing the characterization of miRNAs as markers of breast cancer tumour classes. If in the normal mammary gland, the expression of known miRNAs has been studied in human and mice but the full repertoire of miRNAs expressed in this tissue is not yet available.ResultsTo extend the repertoire of mouse mammary gland expressed miRNAs, we have constructed several libraries of small miRNAs allowing the cloning of 455 sequences. After bioinformatics' analysis, 3 known miRNA (present in miRbase) and 33 new miRNAs were identified. Expression of 24 out of the 33 has been confirmed by RT-PCR. Expression of none of them was found to be mammary specific, despite a tissue-restricted distribution of some of them. No correlation could be established between their expression pattern and evolutionary conservation. Six of them appear to be mouse specific. In several cases, multiple potential precursors of miRNA were present in the genome and we have developed a strategy to determine which of them was able to mature the miRNA.ConclusionThe cloning approach has allowed improving the repertoire of miRNAs in the mammary gland, an evolutionary recent organ. This tissue is a good candidate to find tissue-specific miRNAs and to detect miRNA specific to mammals. We provide evidence for 24 new miRNA. If none of them is mammary gland specific, a few of them are not ubiquitously expressed. For the first time 6 mouse specific miRNA have been identified.
Highlights
MicroRNAs are small non-coding RNAs that have been found to play important roles in silencing target genes and that are involved in the regulation of various normal cellular processes
The sequences of many miRNAs are conserved among distantly related organisms [5], but recent evidences demonstrated the presence of primate-specific miRNAs [6,7]. miRNAs are transcripts which are cleaved from a ~70 nucleotides hairpin precursor by Dicer [8,9]
They regulate gene expression at the posttranscriptional level through binding to their target messager RNAs (mRNAs) by base-pairing and subsequently inducing either translational repression or mRNA destabilization [10]. miRNAs are involved in the regulation of various cellular processes, including cell differentiation, cell proliferation, development and apoptosis [11]
Summary
MicroRNAs (miRNAs) are small non-coding RNAs that have been found to play important roles in silencing target genes and that are involved in the regulation of various normal cellular processes. Until now their implication in the mammary gland biology was suggested by few studies mainly focusing on pathological situations allowing the characterization of miRNAs as markers of breast cancer tumour classes. MiRNAs are transcripts which are cleaved from a ~70 nucleotides hairpin precursor by Dicer [8,9] They regulate gene expression at the posttranscriptional level through binding to their target mRNAs by base-pairing and subsequently inducing either translational repression or mRNA destabilization [10]. They regulate gene expression at the posttranscriptional level through binding to their target mRNAs by base-pairing and subsequently inducing either translational repression or mRNA destabilization [10]. miRNAs are involved in the regulation of various cellular processes, including cell differentiation, cell proliferation, development and apoptosis [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
