Msx1 Homeogene Antisense mRNA in Mouse Dental and Bone Cells

Abstract

Msx1 plays a key role in early dental and cranio-facial patterning. A systematic screening of Msx1 transcripts during late postnatal stages of development evidenced not only sense mRNA but also antisense mRNA in the skeleton. Natural antisenses are able to bind their corresponding sense RNAs and block protein expression. Specific reverse-transcription polymerase chain reaction (RT-PCR) Northern-blotting using riboprobes and primer extension analysis allowed to identify and sequence a mouse 2184-base Msx1 antisense transcript. The transcription start site was located in a region including a consensus TATA box. In situ hybridization evidenced an increase in antisense mRNA expression during dental and bone cell differentiation in prenatal (Theiler stages E15.5-18.5) and newborn mice. This upregulation was related to Msx1 protein downregulation in cells expressing Msx1 sense mRNA. In vitro, transient Msx1 sense and antisense mRNA overexpression was performed in MO6-G3 cells, which pertain to the odontoblast lineage (polarization and dentin sialoprotein and phosphoprotein synthesis). The balance between antisense and sense Msx1 mRNAs appeared to control Msx1 protein levels. These data suggest that a bidirectional transcription of Msx1 homeogene may control Msx1 protein levels, and therefore may be critical in cell communication and differentiation during dental and cranio-facial development and mineralization.

Expression and regulation of the Msx1 natural antisense transcript during development

“…Msx1 AS transcript was proposed to be instrumental postnatally in terminal differentiation, by inhibiting Msx1 protein expression (12,45). Indeed, Msx1 homeoprotein expressing cells were considered as undifferentiated cells, based on in vitro observations that Msx1 (i) inhibits master gene expression such as MyoD (46) and Runx2 (12), (ii) modulates the expression of cell cycle determinants such as cyclin D1 (47) and p19(INK4d) (48), (iii) induces dedifferentiation of myotubes (14), and (iv) is specifically present in progenitor cell niches in adults (49).…”

Could lncRNAs be the Missing Links in Control of Mesenchymal Stem Cell Differentiation?

“…Given the important role of Msx1 in dental and craniofacial development, Msx1-as was shown to be and important osteogenic regulator, negatively affecting Msx1 transcript levels resulting in dose-dependent reduction of Msx1 protein levels (Babajko et al 2009, Berdal et al 2002). Moreover, the cellular location of Msx1 protein is modulated by Msx1-as and Msx1-as can abolish the inhibition of Dlx5 by Msx1.…”

Making sense of Dlx1 antisense RNA

“…Increasing evidence points to a role for non-coding RNAs (ncRNAs) in development and disease, a field rapidly gaining importance (Babajko et al, 2009;Berdal et al, 2002;Blin-Wakkach et al, 2001;Brockdorff et al, 1991;Chen and Carmichael, 2010;Clemson et al, 1996;Costa, 2010;Eberhart et al, 2008;Faghihi and Wahlestedt, 2009;Feng et al, 2006;Ginger et al, 2006;Gupta et al, 2010;Lipovich et al, 2010;Lyle et al, 2000;Nagano et al, 2008;Qureshi et al, 2010;Rinn et al, 2007;Sana et al, 2012;St Laurent et al, 2009;Young et al, 2005). NcRNAs include microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), with an emerging class of lncRNAs that act as endogenous riboregulators of transcription factors (TFs), including lncRNAs that directly bind TF proteins to regulate them (Chen and Carmichael, 2010;Costa, 2010;Hung and Chang, 2010;Hung et al, 2011;Kino et al, 2010;Lipovich et al, 2010;Martianov et al, 2007;Redon et al, 2010;Sana et al, 2012;.…”