Expression of the dystrophin-related protein (utrophin) gene during mouse embryogenesis

The utrophin (UTRN) locus is the autosomal homologue of the DMD (Duchenne muscular dystrophy) gene and encodes a protein, utrophin which is thought to be upregulated in the absence of dystrophin. In this study the spatial and temporal expression of the UTRN gene has been examined during mouse embryogenesis and compared with that of the DMD gene. The patterns of expression of these two genes are very different. Whilst DMD is expressed largely in mesodermal derivatives such as cardiac and striated muscle, UTRN shows a more widespread distribution and is expressed in neural tube, tissues which originate from neural crest and a variety of other sites of non-neural origin. In early embryos UTRN transcripts initially accumulate in the mid-neural plate and thereafter in the caudal neural tube. UTRN mRNA then becomes abundant in a subset of neural crest cell derived tissues, in particular the spinal and facial ganglia and ossifying facial cartilages. UTRN is also expressed in a variety of other sites and organs such as the tendon primordia in the digits, the pituitary, thyroid and adrenal glands, cardiac muscle, kidney and lung, follicles of the vibrissae and the outflow tract of the heart. Several patterns of UTRN expression are apparent and we discuss the possibility that these can be ascribed to a family of mRNAs transcribed from the UTRN gene using alternative promoters.