Regulation of the expression of prostate apoptosis response protein 4 (Par-4) in rat granulosa cells.
The par-4 gene, directs the expression of a protein in the rat ventral prostate after apoptotic stimuli but not growth stimulatory, growth arresting or necrotic signals. Since Par-4 expression appears to be ubiquitous we investigated the possibility of Par-4 having a role in the rat ovary granulosa cells apoptotic death. Par-4 mRNA was detected by RT-PCR with oligonucleotides designed to prime Par-4 leucine zipper in the ovaries of 12 day old rats and reached the higher levels in 24 days old rats. In situ hybridization analysis revealed that Par-4 expression is restricted to granulosa cells. PMSG priming of 24 day old rats for 2 days greatly reduced Par-4 expression in granulosa cells as determined by in situ hybridization, RT-PCR of mRNA and protein immunodetection with Western blot. Granulosa cells placed in serum-fee culture, exhibited increased levels of Par-4 mRNA and protein, in good correlation with the degree of apoptosis. The culture-induced increases in Par-4 are significantly prevented by FSH. Transient transfection of granulosa cells with Par-4 leucine zipper domain that functions as a dominant-negative regulator of Par-4 activity resulted in lower rates of apoptosis while overexpression of the full length Par-4 counteracted FSH effects on apoptosis. Par-4 association with PKCzeta which is supposed to inhibit this kinase mediated antiapoptotic way is also prevented by FSH and, FSH antiapoptotic effects are counteracted by a PKCzeta specific inhibitor. These findings indicate that FSH by suppressing Par-4 expression in the ovary activates PKCzeta-dependent antiapoptotic pathway and suggest that Par-4 is part of the mechanism underlying granulosa cells apoptotic demise.
Gonzalez
Inmaculada Hernandez
IH
Departamento de Bioquímica, Biología Molecular y Fisiología, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain,
Santana
Pino
P
Gonzalez-Robayna
Ignacio
I
Ferrer
Milagros
M
Morales
Victoria
V
Blanco
Felix Lopez
FL
Fanjul
Luisa F
LF
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006064:Gonadotropins, Equine / Q000378:metabolism; D006107:Granulosa Cells / Q000166:cytology / Q000502:physiology*; D006801:Humans; D016350:Leucine Zippers; D010053:Ovary / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D000099221:Protein Kinase C zeta
D051017:Apoptosis Regulatory Proteins; D005640:Follicle Stimulating Hormone; D006064:Gonadotropins, Equine; D011493:Protein Kinase C; D000099221:Protein Kinase C zeta; C101296:prostate apoptosis response-4 protein