Z Gastroenterol 2009; 47 - P1_48
DOI: 10.1055/s-0029-1191802

Differentially expressed microRNAs during myofibroblastic transdifferentiation of Hepatic Stellate Cells

I Strack 1, M Scheffler 1, S Schievenbusch 1, J Riemer 1, A Noetel 1, U Töx 2, M Kwiecinski 1, N Elfimova 1, I Wedemeyer 1, HP Dienes 1
  • 1Institut für Pathologie, Universität zu Köln
  • 2Abteilung für Gastroenterologie und Hepatologie am Abdominalzentrum, Universität zu Köln

Aims: Activated Hepatic Stellate Cells (HSC) play a crucial role in hepatic fibrogenesis. MicroRNAs (miRNAs) are short regulatory RNA that result in posttranscriptional gene repression and are involved in cell differentiation and carcinogenesis. In the present study we analysed the function of miRNA in myofibroblastic transition of HSC and liver fibrogenesis.

Methods: Total RNA was extracted and a miRNA expression profile was analysed by microarray hybridisation and real-time PCR assays of total RNA extracts from primary rat HSC. miR-125b was then either knocked out or elevated in primary HSC by transfection of complementary LNA sequences or miR-125b mimics, respectively. A miR-125b GFP reporter construct was used to evaluate miR-125 function. For induction of experimental fibrosis, bile-duct ligation was performed. Furthermore miRNA expression level was studied in 84 liver biopsies representing different stages of fibrosis.

Results: Microarray analyses revealed 42 differentially expressed miRNAs during in vitro induced myofibroblastic differentiation of primary HSC. miR-22, miR-31, miR-125b and miR-143 were more than 2-fold upregulated. One miRNA, not yet annotated in miRBase, was highly downregulated. Real-time PCR confirmed the expression profile shown by microarray analyses. During fibrogenesis in rat and in man, miR-143 did not alter and miR-22 and miR-125b was moderately repressed (p<0.05). Whereas miR-125b was highly upregulated during myofibroblastic transition, its identified target gene, the promoting factor of pluripotency, Lin28, showed prominent downregulation. miR-125b effects on HSC pluripotency were suggested and targeting of the Lin28–3´UTR-sequence was proven by a miR-125b reporter construct in primary HSC.

Conclusion: miRNA are suggested to be involved in myofibroblastic activation of HSC especiallly miR-125b seems to play a crucial role by regulation of the stem-cell specific factor, Lin28, which is also subject of further studies.