Endothelin-1 stimulates deoxyribonucleic acid synthesis and contraction in testicular peritubular myoid cells.
In the testis, endothelin-1 (ET-1) is produced by Sertoli cells, and it has been proposed to be a paracrine factor participating in the regulation of tubular and interstitial function. The response of purified testicular peritubular myoid cells (TPMC) to ET-1 was investigated in the present study. TPMC expressed a single class of high-affinity receptors that were shown by competitive binding experiments with sarafotoxin-6c to belong to the ETA subtype. The binding of ET-1 to TPMC was followed by rapid internalization of the receptor-ligand complex. ET-1 induced a prompt rise in intracellular Ca2+ concentration that was blunted in Ca(2+)-free medium and in the presence of Mn2+ or of voltage-operated-calcium-channel (VOC) blockers, indicating that both Ca2+ mobilization from intracellular stores and extracellular Ca2+ influx were involved. Thymidine uptake was promoted by ET-1 in a time-dependent manner, and the use of cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp] (BQ123) reduced the incorporation of thymidine. Protein kinase C (PKC) inhibition (100 nM calphostin C) abolished the ET-1 mitogenic effect. ET-1 also promoted TPMC contraction, as evaluated in collagen lattices, in a dose-related manner, with the half-maximal response observed at 1 nM. As in the case of mitogenesis, BQ123 blunted ET-1-induced contraction. PKC inhibition abolished ET-1-induced contraction. These findings indicate that ET-1 promotes DNA synthesis and contraction of TPMC and that both effects are mediated by PKC; they suggest as well that ET-1 may have a physiological role in the interaction between Sertoli cells and TPMC.
Santiemma
V
V
Dipartimento di Fisiopatologia Medica, Universita' di Roma "La Sapienza", Italy.
Beligotti
F
F
Magnanti
M
M
Palleschi
S
S
Silvestroni
L
L
Fabbrini
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017466:Receptors, Endothelin / Q000378:metabolism; D012671:Seminiferous Tubules / Q000187:drug effects* / Q000502:physiology*
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D010456:Peptides, Cyclic; D017466:Receptors, Endothelin; D004247:DNA; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D002118:Calcium