title: Upregulation of proapoptotic microRNA mir-125a after massive small bowel resection in rats.
abstract: OBJECTIVE
  Short bowel syndrome remains a condition of high morbidity and mortality, and current therapeutic options carry significant side effects. To identify new treatments we focused on postresection changes in microRNAs--short noncoding RNAs, which suppress target genes--and suggest a previously undiscovered role for microRNA-125a (mir-125a) in intestinal adaptation.
  
  
  METHODS
  Rats underwent either 80% massive small bowel resection or transection and were harvested after 48 hours. Jejunum was harvested for microRNA microarrays, laser capture microdissection, and RNA and protein analysis. Mir-125a was overexpressed in intestinal epithelium-6 (crypt-derived) cells (IEC-6) and effects on proliferation and apoptosis determined using MTS and flow cytometry. Expression of potential targets of mir-125a in rat jejunum and IEC-6 cells was determined using quantitative real-time polymerase chain reaction (RNA) and Western blotting (protein).
  
  
  RESULTS
  Resection upregulated mir-125a and mir-214 by 2.4-folds and 3.2-folds, respectively. Highest levels of expression were noted in the crypt fraction. Mir-125a overexpression induced apoptosis and resultant growth arrest in IEC-6 cells. The expression of the prosurvival Bcl-2 family member Mcl-1 was downregulated in both mir-125a-overexpressing IEC-6 cells and in jejunum of resected rats, confirming Mcl-1 as a previously undiscovered target of mir-125a.
  
  
  CONCLUSIONS
  Upregulation of mir-125a suppresses the prosurvival protein Mcl1, producing the increase in apoptosis known to accompany the proliferative changes characteristic of intestinal adaptation. Our data highlight a potential role for microRNAs as mediators of the adaptive process and may facilitate the development of new therapeutic options for short bowel syndrome.
authors.affiliation: Department of Surgery, Brigham and Women's Hospital, Boston, MA 02115, USA. anita.balakrishnan@doctors.org.uk
authors.forename: Anita
authors.initials: A
authors.lastname: Balakrishnan
authors.forename: Adam T
authors.initials: AT
authors.lastname: Stearns
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Park
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Dreyfuss
authors.forename: Stanley W
authors.initials: SW
authors.lastname: Ashley
authors.forename: David B
authors.initials: DB
authors.lastname: Rhoads
authors.forename: Ali
authors.initials: A
authors.lastname: Tavakkolizadeh
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation; D005434:Flow Cytometry; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D007421:Intestine, Small / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D061346:Laser Capture Microdissection; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D020411:Oligonucleotide Array Sequence Analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D012778:Short Bowel Syndrome / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation
chemical_list: C579093:Mcl1 protein, rat; D035683:MicroRNAs; C559947:Mirn214 microRNA, rat; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2