The soluble and membrane-anchored forms of heparin-binding epidermal growth factor-like growth factor appear to play opposing roles in the survival and apoptosis of human luteinized granulosa cells.
This study aims to investigate the expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF) and its role in regulating apoptosis of human luteinized granulosa cells (LGC). By using RT-PCR and immunocytochemistry, the expression of HB-EGF and the EGF receptor family was demonstrated. HER4, one of the two cognate receptors for HB-EGF, was found translocated into the nucleus. HB-EGF exists in two forms, the precursor membrane-anchored form and the mature secreted form. Addition of recombinant HB-EGF, which acts as the secreted form, into the cell culture inhibited apoptosis and appeared to stimulate mitosis, indicating that the secreted form is potentially an anti-apoptotic factor and a mitogen for LGC. In contrast, CRM197, a specific inhibitor for the interaction between HB-EGF and the EGF receptor, inhibited rather than enhanced apoptosis, suggesting that the membrane-anchored form constitutively functions as a pro-apoptotic factor for LGC. Furthermore, the finding that apoptosis inhibition by CRM197 in the aggregate cells was much more pronounced than in the single cells indicates that pro-apoptotic activity was carried out in a juxtacrine fashion, as would be expected for the membrane-anchored form of HB-EGF. These data suggest that HB-EGF may be a unique regulator of LGC apoptosis, with two functionally opposing products arising from the same gene.
Pan
Bochen
B
Department of Obstetrics and Gynecology, Asahikawa Medical College, Midorigaoka Higashi 2-1-1-1, Japan. pan@mail.asahikawa-med.ac.jp
Sengoku
Kazuo
K
Goishi
Katsutoshi
K
Takuma
Naoyuki
N
Yamashita
Tsuyoshi
T
Wada
Keiko
K
Ishikawa
Mutsuo
M
D017209:Apoptosis / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000502:physiology*; D005260:Female; D006107:Granulosa Cells / Q000502:physiology*; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins
C587883:HBEGF protein, human; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D004815:Epidermal Growth Factor