Journal of Biomedicine and Biotechnology 
Volume 2006 (2006), Article ID 16806, 7 pages
doi:10.1155/JBB/2006/16806
Research Article

Hypothesis: A Role for Fragile X Mental Retardation Protein in Mediating and Relieving MicroRNA-Guided Translational Repression?

Isabelle Plante1,2 and Patrick Provost1,2

 1Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL (CHUQ), 2705 Boulevard, Sainte-Foy, Québec G1V 4G2, Laurier, Canada
2Department of Anatomy and physiology, Faculty of Medicine, Laval University, Québec G1K 7P4, Canada
Received 8 April 2006; Accepted 2 May 2006

Abstract

MicroRNA (miRNA)-guided messenger RNA (mRNA) translational repression is believed to be mediated by effector miRNA-containing ribonucleoprotein (miRNP) complexes harboring fragile X mental retardation protein (FMRP). Recent studies documented the nucleic acid chaperone properties of FMRP and characterized its role and importance in RNA silencing in mammalian cells. We propose a model in which FMRP could facilitate miRNA assembly on target mRNAs in a process involving recognition of G quartet structures. Functioning within a duplex miRNP, FMRP may also mediate mRNA targeting through a strand exchange mechanism, in which the miRNA* of the duplex is swapped for the mRNA. Furthermore, FMRP may contribute to the relief of miRNA-guided mRNA repression through a reverse strand exchange reaction, possibly initiated by a specific cellular signal, that would liberate the mRNA for translation. Suboptimal utilization of miRNAs may thus account for some of themolecular defects in patients with the fragile X syndrome.