MOLECULAR AND FUNCTIONAL-ANALYSIS OF THE UTROPHIN PROMOTER

Utrophin is a ubiquitously expressed cytoskeletal protein which is an important structural component of the mammalian neuromuscular junction . It shows extensive sequence similarity to dystrophin leading to post ulation that utrophin may be able to compensate for the absence of dys trophin in Duchenne muscular dystrophy (DMD) patients. In order to stu dy the transcriptional control of utrophin expression including its re gulation at the neuromuscular junction, and as a first step in the dev elopment of a potential DMD therapy, we have cloned the utrophin promo ter region from human and mouse. The utrophin promoter is associated w ith a CpG island at the 5'-end of the gene, and sequence analysis of t he 5'-UTR reveals several Sp1 binding sites and the absence of TATA or CAAT motifs. Transcription is initiated at one major and three minor sites. Using deletion constructs, we have defined an active promoter r egion of 155 bp. The first exon and 900 bp upstream display limited se quence conservation between human and mouse. The core sequence TTCCGG of the N box which regulates synaptic expression of other genes is als o present and may be involved in regulating the specific expression of utrophin at the postsynaptic membrane. This study provides the basis for the understanding of the regulatory mechanism that controls utroph in expression and provides the data needed to develop methods for the upregulation of utrophin in DMD patients.