Platelet-derived growth factor effects on purified testicular peritubular myoid cells: binding, cytosolic Ca2+ increase, mitogenic activity, and extracellular matrix production enhancement.
The response of purified rat testicular peritubular myoid cells (PMC) to platelet-derived growth factor (PDGF) was studied. Freshly isolated PMC were devoid of measurable amounts of PDGF-binding sites. However, after 1 day in culture in serum-free conditions, specific high affinity receptors were detected. The estimated binding sites per cell revealed that PMC express more receptors for PDGF-BB, followed by PDGF-AB and PDGF-AA. PDGF treatment of cultured PMC increased the cytosolic Ca2+ concentration, showing a rank order of potencies with PDGF-BB > PDGF-AB > PDGF-AA. PMC proliferation, as measured by direct cell counting, was also stimulated by all three PDGF isoforms, with the same order of potencies observed for the increase in intracellular Ca2+. This effect was inhibited by antibodies to PDGF. Moreover, PDGF treatment increased the release of type IV collagen and fibronectin, and induced the release of type V collagen and laminin. These results demonstrate that testicular PMC are induced to express functionally active PDGF receptors in response to cell culturing. These data suggest that PMC may be a target for PDGF and that PDGF-mediated effects in vivo are dependent on factors regulating the expression of the receptors. The role that PDGF may play in normal and pathological testicular processes is discussed.
Gnessi
L
L
V Clinica Medica, Universitá di Roma La Sapienza, Facoltá di Medicina, Italy.
Emidi
A
A
Scarpa
S
S
Palleschi
S
S
Ragano-Caracciolo
M
M
Silvestroni
L
L
Modesti
A
A
Spera
G
G
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008855:Microscopy, Electron, Scanning; D008934:Mitogens / Q000494:pharmacology*; D009132:Muscles / Q000166:cytology; D009994:Osmolar Concentration; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D011233:Precipitin Tests; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D012671:Seminiferous Tubules; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D017479:Receptors, Platelet-Derived Growth Factor; D002118:Calcium