title: Locked nucleic acid-based in situ hybridisation reveals miR-7a as a hypothalamus-enriched microRNA with a distinct expression pattern.
abstract: MicroRNAs (miRNAs) are short (∼22 nucleotides) noncoding RNA molecules that post-transcriptionally repress the expression of protein-coding genes by binding to 3'-untranslated regions of the target mRNAs. To identify miRNAs selectively expressed within the hypothalamus, a part of the brain that controls vital bodily functions, we employed locked nucleic acid (LNA)-fluorescent in situ hybridisation (FISH). The expression pattern of the mature miRNAs miR-7a, miR-7b, miR-137 and miR-153 in mouse brain tissue sections was investigated. Although all studied miRNAs were present in the hypothalamus, miR-7a, was the only miRNA found to be enriched in the hypothalamus, with low or no expression in other parts of the central nervous system (CNS). Within the hypothalamus, strong miR-7a expression was distinct and restricted to some hypothalamic nuclei and adjacent areas. miR-7a expression was particularly prominent in the subfornical organ, as well as the suprachiasmatic, paraventricular, periventricular, supraoptic, dorsomedial and arcuate nuclei. Identical expression patterns for miR-7a were seen in mouse and rat hypothalamus. By combining LNA-FISH with immunohistochemistry, it was shown that miR-7a was preferentially present in small orexigenic neuropeptide Y/agouti-related protein-containing-neurones located in the ventromedial aspect of the arcuate nucleus but not in large pro-opiomelanocortin/cocaine- and amphetamine-regulated transcript-containing anorexigenic neurones of the ventrolateral part of the arcuate nucleus. The limited and distinct expression of miR-7a in the CNS suggests that miR-7a has a role in post-transcriptional regulation in hypothalamic neurones. Particularly strong expression of miR-7a in neurones located in the ventromedial division of the arcuate nucleus, a subregion with a weak blood-brain barrier, raises the possibility that miR-7a is influenced by circulating hormones and is a regulator of the genes involved in body weight control.
authors: Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors: S
authors: S
authors: Herzer
authors: A
authors: A
authors: Silahtaroglu
authors: B
authors: B
authors: Meister
mesh_terms: D000818:Animals; D001835:Body Weight / Q000235:genetics; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000378:metabolism*; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009841:Oligonucleotides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: C549243:MIRN7 microRNA, mouse; D035683:MicroRNAs; D009841:Oligonucleotides; C477371:locked nucleic acid