MicroRNAs (miRNAs) are abundant small RNA species that have emerged as key regulators in many biological processes. Rodriguez et al. observed that mice deficient in miRNA-155 develop spontaneous inflammation of the lungs and have accompanying defects in antigen presentation as well as in T cell and B cell function. Exploring the same miRNA, Thai et al. observed a similar T and B cell deficiency that resulted in a suboptimal response of the germinal center, which is needed for T cell-mediated antibody production. Although both studies provide some evidence for how this miRNA mediates its effects, the next important step will be to identify the precise mechanism and critical target genes involved.
A. Rodriguez, E. Vigorito, S. Clare, M. V. Warren, P. Couttet, D. R. Soond, S. van Dongen, R. J. Grocock, P. P. Das, E. A. Miska, D. Vetrie, K. Okkenhaug, A. J. Enright, G. Dougan, M. Turner, A. Bradley, Requirement of bic/microRNA-155 for normal immune function. Science 316, 608-611 (2007). [Abstract] [Full Text]
T.-H. Thai, D. P. Calado, S. Casola, K. M. Ansel, C. Xiao, Y. Xue, A. Murphy, D. Frendewey, D. Valenzuela, J. L. Kutok, M. Schmidt-Supprian, N. Rajewsky, G. Yancopoulos, A. Rao, K. Rajewsky, Regulation of the germinal center response by microRNA-155. Science 316, 604-608 (2007). [Abstract] [Full Text]