Expression and function of apoptosis initiator FOXO3 in granulosa cells during follicular atresia in pig ovaries.
In mammalian ovaries, most follicles are lost by atresia before ovulation. It has become apparent that the apoptosis of granulosa cells induces follicular atresia. Forkhead box O3 (FOXO3), also called FKHRL1 (forkhead in rhabdomyosarcoma-like 1), is a proapoptotic molecule that belongs to the FOXO subfamily of forkhead transcription factors. Foxo3-deficient female mice were reported to be infertile because of abnormal ovarian follicular development, but the precise influences of FOXO3 on follicular atresia of mature ovary have not been determined. Therefore, we examined the expression and function of FOXO3 in porcine ovarian follicles and granulosa-derived cells. FOXO3 mRNA levels in granulosa cells of porcine ovaries increased during atresia, while FOXO3 protein was abundant in granulosa cells of early atretic follicles. By immunohistochemistry, the inner surface area of the granulosa layer in early atretic follicles was strongly stained with anti-FOXO3 antibody. The granulosa cells expressing FOXO3 coincided with apoptotic cells, indicating a role of FOXO3 as a proapoptotic factor in granulosa cells of porcine ovaries. In porcine (JC-410) and human (KGN) granulosa-derived cells, cell death was induced by transfection of FOXO3 expression vectors. Expression of the proapoptotic factors Fas ligand (FASLG) and BCL2-like 11 (BCL2L11) was upregulated by FOXO3 in KGN cells. In conclusion, FOXO3 is expressed in porcine ovarian follicles and induces apoptosis in granulosa cells, suggesting that it is a candidate for the initiator of follicular atresia.
Research Unit for Animal Life Sciences, Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Ibaraki, Japan. fukomat@yahoo.co.jp
Fuko
F
Matsuda
Naoko
N
Inoue
Akihisa
A
Maeda
Yuan
Y
Cheng
Takafumi
T
Sai
Hiroshi
H
Gonda
Yasufumi
Y
Goto
Kazuhiro
K
Sakamaki
Noboru
N
Manabe
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D002460:Cell Line; D053222:Fas Ligand Protein / Q000378:metabolism; D005260:Female; D005496:Follicular Atresia / Q000378:metabolism*; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005786:Gene Expression Regulation; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012741:Sexual Maturation; D034421:Sus scrofa
D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; C499517:FOXO3 protein, human; D053222:Fas Ligand Protein; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D008565:Membrane Proteins; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger