Der Einfluss humaner testikulärer Peritubulärzellen auf testikuläre Stammzellen und die Stammzellnische im Hoden: Eine Analyse des «Sekretoms" und in vitro Studien
Zusammenfassung der Projektergebnisse
The aim of the project was to explore the contribution of HTPCs to the SSC niche by performing a secretome analysis and in vitro studies. The results of the project provide novel information about specific features of testicular peritubular cells in man, about the interaction testicular peritubular cells with germ cells and the regulation of testicular blood vessels. In brief: 1. Secretome-studies: We identified the vast secretome and the cellular proteins of HTPCs from 5 individual donors. The MS analysis shows that almost 200 proteins were highly enriched in the supernatant, indicating that HTPCs are highly secretory cells. Of the factors found, several had not previously been identified in the (human) testis. They include for example PTX3 and PEDF. Factor of highest abundance were ECM proteins, including decorin and biglycan, which have functions beyond structural proteins. The lack of true human human SSC hampered the evaluation of the actions of secreted factors. Studies with TCam-2, which were used as surrogate for SSCs, indicated that the sum of secreted factors does not impair their growth. 2. PEDF was one of the most abundant factors of HTPCs. It was likewise found in HTPC-Fs. Is a multifunctional factor with described strong anti-angiogenic actions. We followed this lead and found that it is expressed in human and nonhuman primate testis already before puberty, that activation of the AR increased it mRNA levels and that it indeed acts to repulse HUVECs in co-culture experiments. HTPCs thus may be responsible for the avascular nature of seminiferous tubules. As they also secrete pro-antigenic factor, their activity may play a role in the fine-tuning of testicular microvasculature. The later is strongly related to the position of SSC at the periphery of seminiferous tubules. 3. Mast cell and SSC: In infertility patients MCs expressing tryptase increase significantly in the wall of seminiferous tubules. The receptor for tryptase, PAR-2 was found in SSC (expressing GFRalpha 1) and other germ cells. We found that activation of PAR-2 expressed also by the SSC-surge cell TCam-2 increase mitotic activity and decreased spontaneous apoptosis.
Projektbezogene Publikationen (Auswahl)
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(2011) Human tryptase cleaves pro-nerve growth factor (pro-NGF): hints of local, mast cell-dependent regulation of NGF/pro-NGF action. J Biol Chem 286:31707-13
Spinnler K, Fröhlich T, Arnold GJ, Kunz L, Mayerhofer A
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(2013) Human testicular peritubular cells: more than meets the eye. Reproduction 145:R107-16
Mayerhofer A
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(2014) Are testicular mast cells involved in the regulation of germ cells in man?. Andrology 2:615-22
Windschüttl S, Nettersheim D, Schlatt S, Huber A, Welter H, Schwarzer JU, Köhn FM, Schorle H, Mayerhofer A
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(2014) Pigment-Epithelium Derived Factor (PEDF) and the human ovary: a role in the generation of ROS in granulosa cells. Life Sci 97(2):129-36
Kampfer C, Saller S, Windschüttl S, Berg D, Berg U, Mayerhofer A
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(2014) Secretome analysis of testicular peritubular cells: a window into the human testicular microenvironment and the spermatogonial stem cell niche in man. J Proteome Res 13:1259-69
Flenkenthaler F, Windschüttl S, Fröhlich T, Schwarzer JU, Mayerhofer A, Arnold GJ
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(2015) Human testicular peritubular cells secrete pigment epithelium-derived factor (PEDF), which may be responsible for the avascularity of the seminiferous tubules. Scientific Reports 5:12820
S Windschüttl, C Kampfer , C Mayer , F Flenkenthaler , T Fröhlich , JU Schwarzer, FM Köhn, H Urbanski , GJ Arnold, A Mayerhofer
