The putative peroxisomal gene Pxt1 is exclusively expressed in the testis

Genes reported to be crucial for spermatogenesis are often exclusively expressed in the testis. We have identified a novel male germ cell-specific expressed gene named peroxisomal testis specific 1 (Pxt1) with expression starting at the spermatocyte stage during mouse spermatogenesis. The putative amino acid sequence encoded by the cDNA of the Pxt1 gene contains a conserved Asn-His-Leu (NHL)-motif at its C-terminal end, which is characteristic for peroxisomal proteins. Pxt1-EGFP fusion protein is co-localized with known peroxisomal marker proteins in transfected NIH3T3 cells. In addition, we could demonstrate that the peroxisomal targeting signal NHL is functional and responsible for the correct subcellular localization of the Pxt1-EGFP fusion protein. In male germ cells peroxisomes were reported only in spermatogonia. The Pxt1 gene is so far the first gene coding for a putative peroxisomal protein which is expressed in later steps of spermatogenesis, namely in pachytene spermatocytes. Copyright (C) 2007 S. Karger AG, Basel

Targeted disruption of the mouse Npal3 gene leads to deficits in behavior, increased IgE levels, and impaired lung function.

The non-imprinted in Prader-Willi/Angelman syndrome (NIPA) proteins are highly conserved receptors or transporters. Translocation of NIPA genes were found in patients with Prader-Willi syndrome, and loss-of-function of the NIPA1 gene was identified in hereditary spastic paraplegia. The family of NIPA-like domain containing (NPAL) proteins is closely related to the NIPA proteins, but to date nothing is known about their function. Here, we could demonstrate that both human NPAL3 and mouse Npal3 are ubiquitously expressed and encode highly conserved proteins. To further elucidate the function of the Npal3 gene, knockout (Npal3(-/-)) mice were generated. Intensive phenotypic analyses revealed that disruption of the Npal3 gene results in a pleiotropic phenotype. The function of the nervous system was impaired in both mutant males and females which could be demonstrated in behavioral tests. In addition, in Npal3 mutants the number of NK cells was decreased and changes in IgM, IgG(2), and IgA were observed, indicating that the immune system is also affected. Interestingly, increased IgE levels as well as impaired lung functions were observed in mutant males but not in mutant females. It should be noted that the human NPAL3 gene is located at 1p36.12 -> p35.1, and atopic diseases were previously linked to this genomic region. Thus, the Npal3(-/-) mice could serve as a valuable model system for studying atopic diseases