International Mammalian Genome Society

The 14th International Mouse Genome Conference (2000)

Table of Contents * Genes, Physical Mapping and Sequencing * Gene Identification * Bioinformatics * Common Resources * RIKEN Session * Functional Genomics * Complex Traits * Mutagenesis * Developmental Genetics and Differentiation * Verne Chapman Memorial Lecture I and II

I29. Towards Cloning a Gene Controlling Testicular Descent in Mice

I.P. Gorlov¹, C. E. Bishop^1,2, A. I. Agoulnik^1
1Baylor College of Medicine, Depts. Ob/Gyn,
²Molecular and Human Genetics, Houston, TX, 77030, USA

Cryptorchidism, or impaired testicular descent, is one of the most frequent congenital abnormalities in human. It can result in infertility and dramatically increases the risk of testicular tumors. To date, little is known about the genetic control of this process. A new insertional mouse mutant (crsp - cryptorchidism with white spotting) was recently identified at Baylor College of Medicine. The crsp mutation is associated with a deletion of genomic DNA, caused by an insertion of the transgene. Males homozygous for crsp exhibit intraabdominal cryptorchidism, associated with complete sterility. Heterozygotes are phenotipically normal and fertile. Sequencing of the BACs spanning the crsp deletion interval revealed four novel ESTs. The expression profile of the ESTs was studied using RT-PCR, Northern blot and in situ hybridization. Two of the ESTs studied showed no expression in the tissues examined wheras other two were found to be expressed. One of these  represents an alternative 5'exon of the cg003 gene ubiquitously expressed in all tissues. The expression pattern of the second gene (called can2) is more consistent with its role as a crsp gene. can2 is specifically expressed in gubernaculum and testis. No expression of the gene was detected in the ovary. In situ hybridization demonstrated that can2 is expressed during all stages of spermatogenesis. Sequence of the gene shows that the protein encoded by can2 represents a novel G-protein coupled receptor. We will present expression of this gene in other mouse models of cryptorchidism (Insl3-/- and Tfm mice) and in mice with combinations of two different mutations. Gene targeting experiments are underway to verify possible involvement of the gene into testicular descent.