Mutations in the DKC1 gene are responsible for causing X-linked recessive 
dyskeratosis congenita (DKC) and a more severe allelic variant of the disease, 
Hoyeraal-Hreidarsson syndrome. Both diseases are characterized by progressive 
and fatal bone marrow failure. The nucleolar protein dyskerin is the 
pseudouridine synthase component of the box H+ACA snoRNAs and also interacts 
with the RNA component (human telomerase, hTR) of the telomerase complex. 
Dyskerin is therefore thought to function in the processing of pre-rRNA and of 
the hTR, strengthening the notion that the underlying mechanism of DKC is a 
premature senescence of cells, especially of the rapidly dividing epithelial and 
hemopoietic cells. To examine the functions of dyskerin in vivo, it will be 
necessary to generate mouse models. As a first step, we here provide the genomic 
structure of the mouse Dkc1 gene and expression analysis of the transcript. 
Northern hybridizations revealed the tissue-specific expression of an 
alternative 4.5-kb transcript, in addition to the ubiquitous 2.6-kb transcript. 
RNA in situ hybridizations on day 10.5-18.5 postconception embryos showed a 
ubiquitous expression of Dkc1 with a notably higher level of expression confined 
to the epithelial tissues. In addition, higher level Dkc1 expression was 
confined to embryonic neural tissues as well as to specific neurons in the 
cerebellum (Purkinje cells) and the olfactory bulb (mitral cells) of the adult 
brain. In adult testis, elevated expression was limited to the Leydig cells. The 
results indicate that some of the pertinent functions of dyskerin may be more 
tissue-specific than previously thought and are not limited to rapidly dividing 
cells.