International Mammalian Genome Society

The 16th International Mouse Genome Conference (2002)

Plenary Presentations * Oral Presentations *
Poster Presentations: Complex Genetics and Disease Modifiers * Developmental Genetics * Functional Genomics * Gene Discovery * Genetic Manipulations to Alter Gene Function * Mouse Models: Human Disease and Pharmacogenetics * Sequence Annotation and Comparative Analysis of Genomes *
Attendees * Sponsors * Table of Contents * Photographs * Awards

POSTER 79 - GENETIC COMPLEXITY AT THE 5’-end of Dnahc8, a CANDIDATE GENE FOR EFFECTS ON SPERM FLAGELLAR MORPHOGENESIS AND FUNCTION

O Ogunkua
Temple University School Of Medicine

Pilder S
Temple University School of Medicine

Previous studies have suggested that disparate mutant alleles of the t complex-localized, testis-specific axonemal dynein heavy chain (axDHC) gene, Dnahc8, are responsible for two very different male sterility phenotypes, a sperm flagellar motility defect and a flagellar morphogenesis deficiency, respectively. Initial cloning of full-length Dnahc8 cDNAs revealed two transcripts coding for proteins with different C-termini and a non-conserved N-terminal extension, replete with effector-binding ligands, and nearby O-phosphorylatable/O-GlcNacylatable residues, suggesting possible “Yin-Yang” regulation of ligand-binding activity.  However, northern analyses have suggested that other Dnahc8 5’-ends exist encoding proteins lacking this N-terminal extension.  To further explore this possibility, experiments to isolate and characterize all possible + and t mRNA 5’-ends are currently underway.  Our initial evidence indicates that 5’-ends coding for shortened N-termini probably do not exist; however, numerous 5’UTR cDNA clones show internal deletions or small additions, while all are identical for their final 45 or 34 bases (+ and t ends, respectively). Sequencing across the genomic region containing the 5’UTRs shows that this 45/34 base region is at the 5’-end of the 2nd exon, ~10-kb distal to the 1st  exon.  In addition, a testis-expressed mRNA with no significant open reading frame, the second exon of which is antsense to all but this 45/34 bases, has been isolated, and may serve to regulate differentially the expression of the several isoforms of Dnahc8, depending on the time/place of antisense expression relative to Dnahc8 isoform transcription initiation, and the length of the homology between antisense and each Dnahc8 isoform.