The human genome may encode over 1000 microRNAs (miRNAs), which may target about 60% of mammalian genes and are abundant in many human cell types. MicroRNAs are a class of short (18-23 nucleotide) noncoding RNA molecules which act as a negative regulator of target mRNA stability and translation.  This month the interaction of miRNAs with biliary atresia is examined (JPGN 2012; 54: 186-92).

Using a mouse model, the authors identify miRNA-29 overexpression associated with the downregulation of two mRNA targets related to biliary atresia pathogenesis.  The research has several limitations, including the use of adult mice.  The reason why I highlight this study is that miRNAs are helping elucidate basic disease mechanisms and identifying new therapeutic targets.  Some of these same investigators published “Circulating microRNA is a biomarker of pediatric Crohn disease.” (JPGN: 2011;  53(1): 26-33).  In this study, 11 CD-associated serum miRNA were identified with encouraging diagnostic potential.  These specific miRNAs were found in Crohn disease patients but not in controls and patients with celiac disease.  The sensitivity for Crohn disease was over 80%.

Despite this intriguing research, it not clear whether or when miRNAs will have an important role in bedside management.

Additional references:

• http://www.miR2Disease.org/  Website aims at providing a comprehensive resource of miRNA deregulation in various human diseases.
• http://en.wikipedia.org/wiki/MicroRNA
• Trang, P.; Weidhaas, J. B.; Slack, F. J. (2008). “MicroRNAs as potential cancer therapeutics”. Oncogene 27 Suppl 2: S52–S57.doi:10.1038/onc.2009.353. PMID 19956180. edit
•  Bartel, D. P. (2009). “MicroRNAs: target recognition and regulatory functions”. Cell 136 (2): 215–233. doi:10.1016/j.cell.2009.01.002.PMID 19167326.
• Bartel DP (January 2004). “MicroRNAs: genomics, biogenesis, mechanism, and function”. Cell 116 (2): 281–97. doi:10.1016/S0092-8674(04)00045-5. PMID 14744438.
• Bentwich I, Avniel A, Karov Y, Aharonov R, Gilad S, Barad O, Barzilai A, Einat P, Einav U, Meiri E, Sharon E, Spector Y, Bentwich Z (July 2005). “Identification of hundreds of conserved and nonconserved human microRNAs”. Nat. Genet. 37 (7): 766–70. doi:10.1038/ng1590.PMID 15965474.