title: Sex-different and growth hormone-regulated expression of microRNA in rat liver.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are short non-coding RNAs playing an important role in post-transcriptional regulation of gene expression. We have previously shown that hepatic transcript profiles are different between males and females; that some of these differences are under the regulation of growth hormone (GH); and that mild starvation diminishes some of the differences. In this study, we tested if hepatic miRNAs are regulated in a similar manner.
  
  
  RESULTS
  Using microarrays, miRNA screening was performed to identify sex-dependent miRNAs in rat liver. Out of 324 unique probes on the array, 254 were expressed in the liver and eight (3% of 254) of those were found to be different between the sexes. Among the eight putative sex-different miRNAs, only one female-predominant miRNA (miR-29b) was confirmed using quantitative real-time PCR. Furthermore, 1 week of continuous GH-treatment in male rats reduced the levels of miR-451 and miR-29b, whereas mild starvation (12 hours) raised the levels of miR-451, miR-122a and miR-29b in both sexes. The biggest effects were obtained on miR-29b with GH-treatment.
  
  
  CONCLUSIONS
  We conclude that hepatic miRNA levels depend on the hormonal and nutritional status of the animal and show that miR-29b is a female-predominant and GH-regulated miRNA in rat liver.
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Centre for Molecular Medicine, L8:01, Karolinska University Hospital, 171 76 Stockholm, Sweden. louisa.y.cheung@googlemail.com
authors.forename: Louisa
authors.initials: L
authors.lastname: Cheung
authors.forename: Carolina
authors.initials: C
authors.lastname: Gustavsson
authors.forename: Gunnar
authors.initials: G
authors.lastname: Norstedt
authors.forename: Petra
authors.initials: P
authors.lastname: Tollet-Egnell
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D013006:Growth Hormone / Q000502:physiology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D051381:Rats; D012737:Sex Factors; D013217:Starvation / Q000503:physiopathology
chemical_list: D035683:MicroRNAs; D013006:Growth Hormone