The major function of the reproductive system is to ensure the survival of the species by passing on hereditary traits from one generation to the next. This is accomplished through the production of gametes and the generation of hormones that function in the maturation and regulation of the reproductive system. It is well established that normal development and function of the male reproductive system is mediated by endocrine and paracrine signaling pathways. Fibroblast growth factors (FGFs), their receptors (FGFRs), and signaling cascades have been implicated in a diverse range of cellular processes including: proliferation, apoptosis, cell survival, chemotaxis, cell adhesion, motility, and differentiation. The maintenance and regulation of correct FGF signaling is evident from human and mouse genetic studies which demonstrate that mutations leading to disruption of FGF signaling cause a variety of developmental disorders including dominant skeletal diseases, infertility, and cancer. Over the course of this review, we will provide evidence for differential expression of FGFs/FGFRs in the testis, male germ cells, the epididymis, the seminal vesicle, and the prostate. We will show that this signaling cascade has an important role in sperm development and maturation. Furthermore, we will demonstrate that FGF/FGFR signaling is essential for normal epididymal function and prostate development. To this end, we will provide evidence for the involvement of the FGF signaling system in the regulation and maintenance of the male reproductive system.

Cloning of the fibroblast growth factor receptor (FGFR) adaptor Snt-2 cDNA and the identification of FGFR-1 protein in association with sperm tails, suggested that FGFR-1 signaling was involved in either sperm tail development or function. This hypothesis was tested by the creation of transgenic mice that specifically expressed a dominant-negative variant of FGFR-1 in male haploid germ cells. Mating of transgenic mice showed a significant reduction in pups per litter compared with wild-type littermates. Further analysis demonstrated that this subfertility was driven by a combination of reduced daily sperm output and a severely compromised ability of those sperm that were produced to undergo capacitation prior to fertilization. An analysis of key signal transduction proteins indicated that FGFR-1 is functional on wild-type sperm and probably signals via the phosphatidylinositol 3-kinase pathway. FGFR-1 activation also resulted in the downstream suppression of mitogen activated protein kinase signaling. These data demonstrate the FGFR-1 is required for quantitatively and qualitatively normal spermatogenesis and has a key role in the regulation of the global tyrosine phosphorylation events associated with sperm capacitation.

Mouse models play a key role in the understanding gene function, human development and disease. In 2007, the Australian Government provided funding to establish the Monash University embryonic stem cell-to-mouse (ES2M) facility. This was part of the broader Australian Phenomics Network, a national infrastructure initiative aimed at maximising access to global resources for understanding gene function in the mouse. The remit of the ES2M facility is to provide subsidised access for Australian biomedical researchers to the ES cell resources available from the International Knockout Mouse Consortium (IKMC). The stated aim of the IKMC is to generate a genetically modified mouse ES cell line for all of the ~23,000 genes in the mouse genome. The principal function of the Monash University ES2M service is to import genetically modified ES cells into Australia and to convert them into live mice with the potential to study human disease. Through advantages of economy of scale and established relationships with ES cell repositories worldwide, we have created over 110 germline mouse strains sourced from all of the major ES providers worldwide. We comment on our experience in generating these mouse lines; providing a snapshot of a "clients" perspective of using the IKMC resource and one which we hope will serve as a guide to other institutions or organisations contemplating establishing a similar centralised service.

Protection of cells from osmotic stress is crucial for their survival. Exposure to high osmolarity promotes rapid diffusion of water across cell membranes, dramatically increasing cellular ionic strength, leading to disruption of key proteins/DNA resulting in cell-cycle arrest and apoptosis. The luminal microenvironment of the epididymis is hypertonic; therefore, epididymal cells adapt to the higher osmolarity by accumulating organic osmolytes, such as L-carnitine. Osmolytes do not perturb cells when accumulated in high concentrations, nor do they affect key proteins or damage DNA. Therefore, osmolytes and their transporters are crucial for cell survival. Transporters that are responsible for the accumulation of organic osmolytes have been shown to be regulated at the transcriptional level by hypertonicity. The present study examines the gene expression of known osmoprotective/stress genes in epididymal cells exposed to changes in tonicity. We demonstrate that the osmoprotective/stress pathways present in other organs, such as the kidney, operate in the epididymis, potentially aiding in the protection of its luminal cells and spermatozoa. Further, it was also seen that OCTN2, a transporter that is thought to be responsible for the accumulation of L-carnitine in the epididymal lumen, is regulated in response to changes in tonicity.

SummaryUpregulation of the multidrug resistance protein 1 (LeMDR1) in the protozoan parasite, Leishmania enriettii , confers resistance to hydrophobic drugs such as vinblastine, but increases the sensitivity of these parasites to the mitochondrial drug, rhodamine 123. In order to investigate the mechanism of action of LeMDR1, the subcellular localization of green fluorescent protein (GFP)-tagged versions of LeMDR1 and the fate of the traceable-fluorescent LeMDR1 substrate calcein AM were examined in both Leishmania mexicana and L. enriettii LeMDR1 -/-and overexpressing cell lines. The LeMDR1-GFP chimera was localized by fluorescence microscopy to a number of secretory and endocytic compartments, including the Golgi apparatus, endoplasmic reticulum (ER) and a multivesicular tubule (MVT)-lysosome. Pulse-chase labelling experiments with calcein AM suggested that the Golgi and ER pools, but not the MVT-lysosome pool, of LeMDR1 were active in pumping calcein AM out of the cell. Cells labelled with calcein AM under conditions that slow vesicular transport (low temperature and stationary growth) inhibited export and resulted in the accumulation of fluorescent calcein in both the Golgi and the mitochondria. We propose that LeMDR1 substrates are pumped into secretory compartments and exported from the parasite by exocytosis. Accumulation of MDR substrates in the ER can result in alternative transport to the mitochondrion, explaining the reciprocal sensitivity of drug-resistant Leishmania to vinblastine and rhodamine 123.

No abstract

SNTs (Suc-1 associated Neurotrophic Factor Targets) are FGF signalling adaptors and crucial activators of the MAP/PI3 kinase pathways via FGFRs. Screening a rat testis library identified snt-2 as a potential ODF component. ODFs are a major constituent of the sperm tail that we hypothesise play an active role in motility. Using western blot analysis I have localised Fgfr-1 to the sperm tail. As such, I propose that Fgf signalling through snt-2 is involved in sperm tail development/function. To test this hypothesis, I created transgenic mice carrying a dominant-negative variant of Fgfr-1 driven by the protamine 1 promoter (haploid specific). Breeding experiments confirmed males were fertile, although one line showed a tendency towards reduced pup numbers. This effect was strengthened by Daily Sperm Production (DSP), showing significantly reduced DSP (30%↓) compared to wt mice. Transgene expression levels were expressed up to 70 times above native mRNA levels in wt mice; however there was a concurrent up-regulation of the native receptor in transgenic mice. Cumulatively this resulted in only a 6x over-expression in transgene: native mRNA, and illustrated the presence of a feedback mechanism controlling Fgfr-1 expression. To increase transgene expression, I crossed independent lines (double heterozygous, DH) males. Breeding experiments showed males from 1 cross were significantly subfertile (2 v. 10 in wt mice) . DSPs were further reduced, (41%↓) compared to wt mice. Collectively this data shows Fgfr-1 signalling is required for quantitatively normal spermiogenesis, but is also likely to have a post testicular role in sperm function. I hypothesise this is mediated via activation/regulation of motility through the MAP/PI3 kinase pathways. Further, these mouse models provide compelling evidence that infertility in Kallmann's Syndrome patients is composed of both hypothalamic and testicular components. These mice will provide valuable insights into the signal transduction mechanisms controlling sperm function and avenues for contraceptive development.

Male infertility is often a result of irregular sperm development/function. The identification of snt-2 (Suc-1 associated Neurotrophic Factor Target 2) and Fgfr-1 to the sperm tail, lead to the hypothesis that Fgf signalling through snt-2 is involved in sperm tail development/function. To test this hypothesis, transgenic mice carrying a dominant-negative variant of Fgfr-1, driven by the protamine 1 promoter (haploid specific) were created. Breeding experiments confirmed male fertility; however, one line was significantly sub-fertile and demonstrated a significantly reduced daily sperm production (DSP, 30%↓). Transgene expression levels were up to 70 times above native mRNA levels in wt mice; however, there was a concurrent upregulation of the native receptor in transgenic mice, resulting in only a 6× over-expression in transgenic:native mRNA. To increase transgene expression, independent lines were crossed (double heterozygous, DH). DH transgene expression levels were up to 120 times above the native mRNA in wild type mice, resulting in a 20× over-expression in transgenic:native mRNA. Breeding experiments showed males from 1 cross were significantly subfertile with DSPs further reduced (41%↓). Collectively this data shows Fgfr-1 signalling is required for quantitatively normal spermiogenesis. Given the millions of sperm that mice produce, a 40%↓ in DSP is unlikely to be responsible for the sub-fertility observed i.e. 2 v. 9 pups/litter. Therefore, a disruption of Fgfr-1 signalling may also induce a post-testicular phenotype. Western blot analysis, using tyrosine phosphorylation as a surrogate marker of sperm capacitation, showed transgenic mice had a significantly attenuated ability to initiate capacitation. As capacitation is an absolute requirement for fertilisation, the absence of capacitating capability is probably the major contributor to the sub-fertility seen in the transgenic mice. This research demonstrates for the first time that the Fgfr-1 signalling cascade is one of several pathways associated with sperm development and function.