title: Signaling by TGF-betas in tubule cultures of adult rat testis.
abstract: Although signal transduction of transforming growth factor-betas (TGF-βs) is well characterized in individual cell types, data about TGF-β signaling in a cellular context is still scarce. In this study, we used ex vivo tubule cultures from adult rat testis to investigate TGF-β signaling. We show for the first time in testicular tubules, that TGF-βs also signal via the BMP type I receptors, with ALK2 used by TGF-β1 and ALK3 and ALK6 by TGF-β2. This signal transduction is mediated via Smad3 as well as via Smad1. In contrast, BMPs (BMP2 and BMP7) do not signal via the high-affinity type I and type II TGFβ receptors, TBR1 or TBR2. Furthermore, treatment of tubule cultures with either TGF-β1 or TGF-β2 had profound significant stimulatory effects on secretion of plasminogen activator-1 (PAI-1) through utilization of TGF-β and BMP receptors. Specific inhibitors for either TBR1 or BMP receptors yielded nearly complete inhibition of TGF-β signaling. The TBR1-TBR2 signalosome was detected with Duolink upon stimulation with either TGF-β1 or TGF-β2, predominantly in spermatogenic cells of the adult rat testis, particularly in elongated spermatids. In summary, this examination of intact rat testicular tubules demonstrated for the first time that TGF-βs signal mainly through TBR1 and TBR2 but also use BMP receptors, including for secretion of PAI-1. Whereas ALK2 participates in the TGF-β1-induced TBR1-TBR2 signalosome, ALK3 and ALK6 are involved in signaling of TGF-β2. Detection of the TBR1-TBR2 signalosome in late spermiogenic cells indicates a post-meiotic activity.
authors.affiliation: Center of Gynecology and Obstetrics, Faculty of Medicine, Justus Liebig University Giessen Giessen, Germany.
authors.forename: Kai-Hui
authors.initials: KH
authors.lastname: Chan
authors.affiliation: Institute of Biochemistry, Justus Liebig University GiessenGiessen, Germany; Department of Reproductive Biology, Leibniz Institute for Farm Animal Biology (FBN)Germany.
authors.forename: Sebastian P
authors.initials: SP
authors.lastname: Galuska
authors.affiliation: Center of Gynecology and Obstetrics, Faculty of Medicine, Justus Liebig University Giessen Giessen, Germany.
authors.forename: Pradeep Kumar
authors.initials: PK
authors.lastname: Kudipudi
authors.affiliation: Center of Gynecology and Obstetrics, Faculty of Medicine, Justus Liebig University Giessen Giessen, Germany.
authors.forename: Mohammad Assad
authors.initials: MA
authors.lastname: Riaz
authors.affiliation: Centre for Reproductive Health, Hudson Institute for Medical ResearchMelbourne, Australia; Department of Molecular and Translational Sciences, School of Clinical Science, Monash UniversityMelbourne, Australia.
authors.forename: Kate L
authors.initials: KL
authors.lastname: Loveland
authors.affiliation: Center of Gynecology and Obstetrics, Faculty of Medicine, Justus Liebig University Giessen Giessen, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Konrad
keywords: BMPs; PAI-1; SMAD; TGF-beta signalosome; TGF-betas