Department of Obstetrics and Gynecology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe, 650-0017, Japan
1 To whom correspondence should be addressed. E-mail: maruo{at}kobe-u.ac.jp
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: corpus luteum/granulosa luteal cells/heparin-binding epidermal growth factor-like growth factor (HB-EGF)/human epidermal growth factor receptor (HER)
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The epidermal growth factor (EGF) family includes EGF, heparin-binding epidermal growth factor-like growth factor (HB-EGF), TGF, amphiregulin, betacellulin, epiregulin, neuregulins, and neuregulin-2S (Riese and Stein, 1998
). These ligands interact with human EGF receptor (HER) that belongs to the superfamily of receptor tyrosine kinases (Olayioye et al., 2000
). The HER family is composed of four members: EGF receptor (also termed ErbB1/HER1), ErbB2/Neu/HER2, ErbB3/HER3, and ErbB4/HER4 (Riese and Stein, 1998
; Olayioye et al., 2000
).
HB-EGF is a 22 kDa protein that was first identified in the macrophage-like cell-conditioned medium (Higashiyama et al., 1991). HB-EGF is synthesized as a transmembrane protein (proHB-EGF) that can be cleaved proteolytically to release mature soluble HB-EGF (sHB-EGF) (Higashiyama et al., 1992
; Ono et al., 1994
; Goishi et al., 1995
). In contrast to EGF that binds to HER1, but not to HER4, HB-EGF binds to its cognate receptors, HER1 and HER4 (Elenius et al., 1997
), as well as cell surface heparin sulphate proteoglycan via its heparin-binding domain (Higashiyama et al., 1993
; Thompson et al., 1994
). HB-EGF has been implicated in a variety of physiological and pathological processes such as wound healing (Marikovsky et al., 1993
), blastocyst implantation and placentation (Yoo et al., 1997
; Leach et al., 1999
), heart function (Iwamoto et al., 2003
), cell survival (Miyoshi et al., 1997
; Takemura et al., 1997
; Zushi et al., 1997
; Horikawa et al., 1999
; Iwamoto et al., 1999
; Nguyen et al., 2000
; Fang et al., 2001
; Michalsky et al., 2001
; Farkas and Krieglstein, 2002
), and oncogenic transformation (Fu et al., 1999
).
HB-EGF mRNA has been shown to be expressed in the porcine corpus luteum (Kennedy et al., 1993) and human luteinized granulosa cells isolated from follicular aspirates of patients undergoing IVF treatment (Pan et al., 2002
). However, little information is available regarding the expression pattern of HB-EGF and the HER family in the human corpus luteum and the physiological role of HB-EGF in the luteal growth and regression. This study was conducted to elucidate gene expression and immunolocalization of HB-EGF, HER1 and HER4 in the human corpus luteum by semiquantitative RTPCR analysis and immunohistochemistry.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Immunohistochemistry
The ovarian tissues obtained were fixed in 10% buffered neutral formalin, dehydrated and embedded in paraffin. Sections of 4 µm were deparaffinized followed by standard histological techniques. Immunohistological staining was performed by avidinbiotin immunoperoxidase method using a polyvalent immunoperoxidase kit (Omnitags, Lipshow, MI, USA). Goat polyclonal antibody raised against the carboxy terminus of HB-EGF (M-18; Santa Cruz Biotechnology, Inc., USA), mouse monoclonal antibodies against HER1 (Ab-10; Neo Markers, CA, USA) and HER4 (Ab-1; Neo Markers) were used as the primary antibodies at the dilutions of 1:100 respectively. The anti-HB-EGF antibody (M-18) recognizes membrane-bound precursor HB-EGF (proHB-EGF) containing a single peptide and transmembrane domain. The first incubation with primary antibodies was followed by the second incubation with biotinylated polyvalent antibody and the third incubation with avidinhorseradish peroxidase. Chromogenic reaction was developed by incubation with a freshly prepared solution of tetrahydrochloride diaminobenzidine and hydrogen peroxide. The sections were counterstained with Harris haematoxylin, mounted with glycerin phosphate buffer solution and examined microscopically. The following control procedures were undertaken to assure the specificity of the immunological reactions. Adjacent control sections were subjected to the same immunoperoxidase method, except that the primary antibodies against HB-EGF, HER1 and HER4 were replaced by non-immune goat or mouse IgG (Miles, Erkhardt, IN, USA) at the same dilution as the specific antibodies respectively. In the above-mentioned controls, the replacement of the specific primary antibodies with non-immune IgG resulted in a lack of positive immunostaining. The first trimester early placental tissue was used as a positive control for HER1. Immunostained sections were analysed by three observers in a blinded fashion.
Semiquantitative RTPCR
The corpus luteum was removed from the ovaries, and total RNA was obtained from tissues using RNeasy Mini Kit (Qiagen, Inc., Chatsworth, CA, USA). First strand complementary DNA (cDNA) for HB-EGF, HER1 and HER4 was synthesized from 2 µg total RNA using an Omniscript RT Kit (Qiagen, Inc., Chatsworth, CA, USA). PCR was performed using 1 µl cDNA as template, 6.25 pmol/l of each primer, 2.5 mmol/l dNTP, 0.125 IU Taq DNA polymerase (Roche Diagnostics Inc., Mannheim, Germany), 1xreaction buffer containing 10 mmol/l TrisHCl (pH 8.3), 50 mmol/l KCl, 1.5 mmol/l MgCl2 and 0.01% gelatin in 25 µl reaction volume. The amplification procedure, performed on a Gene Amp PCR System 9600-R (Perkin Elmer Corp., Norwalk, CT, USA), was as follows: initial denaturation step at 94°C for 5 min, denaturation step at 94°C for 30 s, annealing step at 55°C for 30 s, and extension step at 72°C for 30 s. The reactions were subjected to 34 cycles using human-specific PCR primers for HB-EGF (sense primer: 5'-ACAAGGAGGAGCACGGGAAAAG-3', antisense primer: 5'-CGATGACCAGCAGACAGACAGATG-3'), HER1 (sense primer: 5'-CAGCGCTACCTTGTCATTCAG-3', antisense primer: 5'-TCATACTATCCTCCGTGGTCA-3'), and HER4 (sense primer: 5'-AGTTTTCAAGGATGGCTCGAGACCCTC-3', antisense primer: 5'-AGCTTACACCACAGTATTAAGGTGTCT-3'). In addition, tubes containing all PCR components except the RT reaction mixture were also amplified, which served as a negative control to check for the presence of DNA that may have been carried over from a previous reaction. RTPCR of RNA extracted from human placental tissue was used as the positive control. PCR for -actin (sense primer: 5'-CTTCTACAATGAGCTGCGTG-3', antisense primer: 5'-TGATGAGGTAGTCAGTCAGG-3') was performed on all the samples to test for the possibility of RNA degradation or RNA transcription default. The PCR products specific for HB-EGF, HER1, HER4 and
-actin were visualized under UV light following gel electrophoresis on a 3% agarose gel stained with ethidium bromide, and then photographed with Polaroid MP-4 Camera (Polaroid, USA). The bands were scanned with GT-9700F (Epson Co., Tokyo, Japan) and qualified with NIH Image version 1.60 (National Institutes of Health, Bethesda, MD, USA). The PCR products were cloned and the sequence analysis revealed their specificity. The intensities of the bands representing HB-EGF, HER1 and HER4 mRNA were expressed as the ratio to the intensities of the bands representing
-actin mRNA performed in the same experiment. The experiments were repeated with at least three independent specimens with the similar results.
Statistical analysis
The data were expressed as the mean ± SD from at least three independent experiments. Statistical significance was evaluated using one-way analysis of variance with Stat View 4.1 software (SAS Institute, Inc., USA) for Macintosh, followed by post hoc testing using Fishers protected least-significant-difference test. P< 0.05 was considered significant.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
Immunohistochemical localization of HER1 in the corpus luteum
Immunostaining for HER1 was very weak in the cytoplasm and cell membranes of a few granulosa luteal cells only in the early luteal phase (Figure 2A) and mid-luteal phase (Figure 2B). No immunostaining for HER1 was detected in the regressing corpus luteum in the late luteal phase (Figure 2C) and in the corpus albicans (Figure 2D). The stromal cells surrounding the corpus luteum and corpus albicans were also negative for immunostaining of HER1. Replacement of the primary antibody with non-immune mouse IgG resulted in a lack of positive immunostaining of the lutein cells (Figure 2E). The early placental tissue was used as a positive control, which showed immunoreactivity for HER1 only in the syncytiotrophoblasts (Figure 2F).
|
Immunohistochemical localization of HER4 in the corpus luteum
Immunostaining for HER4 in the corpus luteum was positive in the cytoplasm and cell membranes of granulosa luteal cells in the early luteal phase (Figure 3A). Immunostaining for HER4 in those cells decreased in the mid-luteal phase (Figure 3B), and became negative in the late luteal phase (Figure 3C). No immunostaining for HER4 was detected in the corpus albicans (Figure 3D). The stromal cells surrounding the corpus luteum and corpus albicans were negative for immunostaining of HER4. Replacement of the primary antibody with non-immune mouse IgG resulted in a lack of positive immunostaining of the luteal cells (Figure 3E).
|
Expression of mRNA encoding for HB-EGF and HER family in the corpus luteum
Semiquantitative RTPCR revealed the presence of a predicted 276 bp fragment of mRNA for HB-EGF, a 729 bp fragment of mRNA forHER1, and a 527 bp fragment of mRNA for HER4 in the human corpus luteum (Figure 4A). HB-EGF mRNA expression significantly increased in the mid-luteal phase compared with that in the early luteal phase, and decreased in the late luteal phase (Figure 4B). The expression pattern of HER1 mRNA paralleled that of HB-EGF mRNA during the course of the luteal phase, whereas HER4 mRNA expression was most abundant in the early luteal phase and thereafter decreased during the mid- and late luteal phase (Figure 4B).
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
In the present study, immunoreactive HB-EGF was first detected in cytoplasm of granulosa luteal cells in the early luteal phase, and then in both the cytoplasm and cell membranes of those cells in the mid-luteal phase. This suggests that HB-EGF is synthesized in cytoplasm of granulosa luteal cells and subsequently transferred to the cell membranes.
The factors that regulate HB-EGF expression in the ovary remain unknown. However, our results showing the stage-dependent changes in HB-EGF expression during the luteal phase imply that HB-EGF expression may be under the control of sex-steroid hormones. The expression of HB-EGF in the uterus has been shown to be regulated by sex-steroid hormones. In the uterus of ovariectomized mouse and rat, treatment with 17-estradiol significantly enhances HB-EGF mRNA levels in uterine epithelial cells, whereas combined treatment with 17
-estradiol and progesterone significantly enhances HB-EGF mRNA levels in uterine stromal cells, but reduces HB-EGF mRNA levels in uterine epithelial cells (Wang et al., 1994
; Zhang et al., 1994
). A recent study has demonstrated that in immature peudopregnant rat models, HCG injection rapidly increased HB-EGF mRNA levels (Pan et al., 2004
). Treatment of cultured granulosa luteal cells with 17
-estradiol and/or progesterone will clarify the effects of sex-steroid hormones on the induction of HB-EGF expression in the corpus luteum.
Accumulating evidence has demonstrated that HB-EGF plays a vital role in the regulation of cell survival. The sHB-EGF has been shown to be a potent autocrine/paracrine mitogen for fibroblasts, smooth muscle cells, keratinocytes, and endometrial stromal cells (Higashiyama et al., 1991; Marikovsky et al., 1993
; Chobotova et al., 2002
), and a chemoattractant for smooth muscle cells (Higashiyama et al., 1993
). The proHB-EGF is biologically active as a juxtacrine growth factor (Ono et al., 1994
; Nakagawa et al., 1996
; Iwamoto and Mekada, 2000
). The proHB-EGF promotes cell survival of renal epithelial cells (Takemura et al., 1997
) and protects skeletal myotubes (Horikawa et al., 1999
) and hepatoma cells (Miyoshi et al., 1997
) from apoptosis. In contrast, Iwamoto et al. (1999)
reported that the proHB-EGF induces apoptosis of haematopoietic cells through the oligomerization of HER1.
Although the physiological function of HB-EGF in the human ovary remains to be fully understood, it has been reported that sHB-EGF inhibits apoptosis of cultured human luteinized granulosa cells and stimulates the mitosis of those cells, but that proHB-EGF functions as a pro-apoptotic factor in those cells mediated through HER1 in a juxtacrine fashion in vitro (Pan et al., 2002). The authors suggest that sHB-EGF may stimulate luteal cell growth and survival during luteal development, whereas proHB-EGF may initiate apoptosis of luteal cells during regression of the corpus luteum. The precise molecular mechanism by which HB-EGF affects the growth and apoptosis of granulosa luteal cells in the human corpus luteum remains to be elucidated.
Several investigators have demonstrated the presence of high affinity EGF binding sites in human granulosa luteal cells (Budnik and Mukhopadhyay, 1996), and immunolocalization of HER1 in the human corpus luteum (Maruo et al., 1993
; Scurry et al., 1994
; Tekpetey et al., 1995
). In the present study, semiquantitative RTPCR analysis revealed the expression of mRNA encoding for HER1 and HER4 in the human corpus luteum. These results suggest the possible formation of HER1HER4 heterodimers in the human corpus luteum. Pan et al. (2002)
showed the presence of all the four members of HER receptor (HER1, HER2, HER3 and HER4) mRNA in cultured human luteinized granulosa cells isolated from follicular aspirates of patients undergoing IVF treatment. The discrepancy in HER expression in granulosa luteal cells between the data obtained by Pan et al. (2002)
and the results presented here might be due to the effect of HCG administration and/or the use of different primers in the RTPCR experiments reported. Our immunohistochemical studies demonstrated the stage-dependent expression of HER1 and HER4 in granulosa luteal cells in the human corpus luteum. Since HER1 expression was either absent or present at very low levels in granulosa luteal cells, HB-EGF in granulosa luteal cells may function through interaction with HER4 in those cells. The mechanism that up-regulates HER expression in granulosa lutein cells remains poorly understood, but HB-EGF may affect HER expression in corpus luteum through activation of HER signalling.
The ligand binding to HER stimulates receptor phosphorization (Riese and Stein, 1998; Olayioye et al., 2000
). HER1 signalling results in proliferation, migration, gene transcription, cell cycle progression, and cell survival (Prenzel et al., 2001
), whereas HER4 mediates proliferation, cell survival, and chemotaxis (Junttila et al., 2000
). Thus, the coordinated up-regulation of HB-EGF and HER4 protein expression, but not HER1 protein expression, may act to enhance the physiological responses in granulosa luteal cells through increased HER4 signalling during early and mid-luteal phase, while the down-regulation of its expression in the late luteal phase may result in the suppression of biological actions. Taken together, enhanced expression of the transmembrane form of HB-EGF in the corpus luteum in the mid-luteal phase may regulate the proliferation and survival of granulosa luteal cells in a juxtacrine manner and through activating HER4 signalling. Due to the very low expression of HER1 protein in granulosa luteal cells, HER1 is unlikely to participate in regulating luteal growth and regression.
In conclusion, our results demonstrated the stage-dependent changes in HB-EGF and HER system in the corpus luteum, suggesting that the interaction between HB-EGF and HER may play a critical role in the regulation of luteal growth and regression. Further studies will be required to elucidate the effects of HB-EGF on the proliferation and apoptosis of granulosa luteal cells and the regulatory factors responsible for the induction of HB-EGF and HER expression in human granulosa luteal cells.
![]() |
Acknowledgements |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Chobotova K, Muchmore M-E, Carver J, Yoo H-J, Manek S, Gullick WJ, Barlow DH and Mardon HJ (2002) The mitogenic potential of heparin-binding epidermal growth factor in the human endometrium is mediated by the epidermal growth factor receptor and is modulated by tumor necrosis factor-. J Clin Endocrinol Metab 87,57695777.
Corner GWJr (1956) The histological dating of the human corpus luteum of menstruation. Am J Anat 98,377401.[CrossRef][ISI][Medline]
Elenius K, Paul S, Allison G, Sun J and Klagsbrun M (1997) Activation of HER4 by heparin-binding epidermal growth factor stimulates chemotaxis but not proliferation. EMBO J 16,12681278.
Fang L, Li G, Liu G, Lee SW and Aaronson SA (2001) p53 induction of heparin-binding EGF-like growth factor counteracts p53 growth suppression through activation of MAPK and PI3K/Akt signaling cascades. EMBO J 20,19311939.
Farkas LM and Krieglstein K (2002) Heparin-binding epidermal growth factor-like growth factor (HB-EGF) regulates survival of midbrain dopaminergic neurons. J Neural Transm 100,267277.[CrossRef]
Fu S-L, Bottoli I, Goller M and Vogt PK (1999) Heparin-binding epidermal growth factor-like growth factor, a v-Jun target gene, induces oncogenic transformation. Proc Natl Acad Sci USA 96,57165721.
Goishi K, Higashiyama S, Klagsbrun M, Nakano N, Umata T, Ishikawa M, Mekada E and Taniguchi N (1995) Phorbol ester induces the rapid processing of cell surface heparin-binding EGF-like growth factor: conversion from juxtacrine to paracrine growth factor activity. Mol Biol Cell 6,967980.[Abstract]
Higashiyama S, Arraham JA, Miller J, Fiddes JC and Klagsbrun M (1991) A heparin-binding growth factor secreted by macrophage-like cells that is related to EGF. Science 251,936939.[ISI][Medline]
Higashiyama S, Lau K, Besner GE, Abraham JA and Klagsbrun M (1992) Structure of heparin-binding EGF-like growth factor. J Biol Chem 267,62056212.
Higashiyama S, Abraham JA and Klagsbrun M (1993) Heparin-binding EGF-like growth factor stimulation of smooth muscle cell migration: dependence on interactions with cell surface heparin sulfate. J Cell Biol 122,933940.[Abstract]
Horikawa M, Higashiyama S, Nomura S, Kitamura Y, Ishikawa M and Taniguchi N (1999) Upregulation of endogenous heparin-binding EGF-like growth factor and its role as a survival factor in skeletal myotubes. FEBS Lett 459,100104.[CrossRef][ISI][Medline]
Iwamoto R, Handa K and Mekada E (1999) Contact-dependent growth inhibition and apoptosis of epidermal growth factor (EGF) receptor-expressing cells by the membrane-anchored form of heparin-binding EGF-like growth factor. J Biol Chem 274,2590625912.
Iwamoto R and Mekada E (2000) Heparin-binding EGF-like growth factor: a juxtacrine growth factor. Cytokine Growth Factor Rev 11,335344.[CrossRef][ISI][Medline]
Iwamoto R, Yamazaki S, Asakura M, Takashima S, Hasuwa H, Miyado K, Adachi S, Kitakaze M, Hashimoto K, Raab G et al (2003) Heparin-binding EGF-like growth factor and ErbB signaling is essential for heart function. Proc Natl Acad Sci USA 100,32213226.
Junttila TT, Sundvall M, Määttä JA and Elenius K (2000) ErbB4 and its isoforms. Selective regulation of growth factor responses by naturally occurring receptor variants. Trends Cardiovasc Med 10,304310.[CrossRef][ISI][Medline]
Kennedy TG, Brown KD and Vaughan TJ (1993) Expression of the genes for the epidermal growth factor receptor and its ligands in porcine corpus lutea. Endocrinology 132,18571859.[Abstract]
Leach RE, Khalifa R, Ramirez ND, Das SK, Wang J, Dey SK, Romero R and Armant DR (1999) Multiple roles for heparin-binding epidermal growth factor-like growth factor are suggested by its cell-specific expression during the human endometrial cycle and early placentation. J Clin Endocrinol Metab 84,33553363.
Marikovsky M, Breuing K, Liu PY, Eriksson E, Higashiyama S, Farber P, Abraham J and Klagsbrun, M (1993) Appearance of heparin-binding EGF-like growth factor in wound fluid as a response to injury. Proc Natl Acad Sci USA 90,38893893.
Maruo T, Ladines-Llaven CA, Samoto T, Matsuo H, Manalo AS, Ito H and Mochizuki M (1993) Expression of epidermal growth factor and its receptor in the human ovary during follicular growth and regression. Endocrinology 132,924931.[Abstract]
Michalsky MP, Kuhn A, Mehta V and Besner GE (2001) Heparin-binding EGF-like growth factor decreases apoptosis in intestinal epithelial cells in vitro. J Pediatr Surg 36,11301135.[CrossRef][ISI][Medline]
Miyoshi E, Higashiyama S, Nakagawa T, Hayashi N and Taniguchi N (1997) Membrane-anchored heparin-binding epidermal growth factor-like growth factor acts as a tumor survival factor in a hepatoma cell line. J Biol Chem 272,1434914355.
Nakagawa T, Higashiyama S, Mitamura T, Mekada E and Taniguchi N (1996) Amino-terminal processing of cell surface heparin-binding epidermal growth factor up-regulates its juxtacrine but not its paracrine growth factor activity. J Biol Chem 271,3085830863.
Nguyen H, Bride SH, Badawy A-B, Adam RM, Lin J, Orsola A, Guthrie PD, Freeman MR and Peters CA (2000) Heparin-binding EGF-like growth factor is up-regulated in the obstructed kidney in a cell- and region-specific manner and acts to inhibit apoptosis. Am J Pathol 156,889898.
Olayioye MA, Neve RM, Lane HA and Hynes NE (2000) The ErbB signaling network: receptor heterodimerization in development and cancer. EMBO J 19,31593167.
Ono M, Raab G, Lau K, Abraham JA and Klagsbrun M (1994) Purification and characterization of transmembrane forms of heparin-binding EGF-like growth factor. J Biol Chem 269,3131531321.
Pan B, Sengoku K, Goishi K, Takuma N, Yamashita T, Wada K and Ishikawa M (2002) 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. Mol Hum Reprod 8,734741.
Pan B, Sengoku K, Takuma N, Goishi K, Horikawa M, Tamate K and Ishikawa M (2004) Differential expression of heparin-binding epidermal growth factor-like growth factor in the rat ovary. Mol Cell Endocrinol 214,18.[CrossRef][ISI][Medline]
Prenzel N, Fischer OM, Streit S, Hart S and Ullrich A (2001) The epidermal growth factor receptor family as a central element for cellular signal transduction and diversification. Endocrine-Related Cancer 8,1131.
Riese DJ II and Stein DF (1998) Specificity within the EGF family/ErbB receptor family signaling network. BioEssays 20,4148.[CrossRef][ISI][Medline]
Scurry JP, Hamand KA, Astley SB, Leake RE and Wells M (1994) Immunoreactivity of antibodies to epidermal growth factor, transforming growth factors alpha and beta, and epidermal growth factor receptor in the premenopausal ovary. Pathology 26,130133.[ISI][Medline]
Takemura T, Kondo S, Homma T, Sakai M and Marris RC (1997) The membrane-bound form of heparin-binding epidermal growth factor-like growth factor promotes survival of cultured renal epithelial cells. J Biol Chem 272,3103631042.
Tekpetey FR, Daniel SAJ and Yuzpe A (1995) Epidermal growth factor (EGF) receptor localization in cultured human granulosa lutein cells and the stimulation of progesterone production by EGF and transforming growth factor- (TGF-
). J Assist Reprod Genet 12,720727.[ISI][Medline]
Thompson SA, Higashiyama S, Wood K, Pollitt NS, Damm D, McEnroe G, Garrick B, Ashton N, Lau K, Hancock N, Klagsbrun M and Abraham JA (1994) Characterization of sequences within heparin-binding EGF-like growth factor that mediate interaction with heparin. J Biol Chem 269,25412549.
Wang X-N, Das SK, Damm D, Klagsbrun M, Abraham JA and Dey SK (1994) Differential regulation of heparin-binding epidermal growth factor-like growth factor in the adult ovariectomized mouse uterus by progesterone and estrogen. Endocrinology 135,12641271.[Abstract]
Webb R, Woad KJ and Armstrong DG (2002) Corpus luteum (CL) function: local control mechanisms. Domest Anim Endocrinol 23,277285.[CrossRef][ISI][Medline]
Yoo HJ, Barlow DH and Mardon HJ (1997) Temporal and spatial regulation of expression of heparin-binding epidermal growth factor-like growth factor in the human endometrium: a possible role in blastocyst implantation. Dev Genet 21,102108.[CrossRef][ISI][Medline]
Zhang Z, Funk C, Roy D, Glasser S and Mulholland J (1994) Heparin-binding epidermal growth factor-like growth factor is differentially regulated by progesterone and estradiol in rat uterine epithelial and stromal cells. Endocrinology 134,10891094.[Abstract]
Zushi S, Shimomura Y, Kiyohara T, Miyazaki, Y, Tsutsui S, Sugimachi M, Higashimoto Y, Kanayama S and Matsuzawa Y (1997) Role of heparin-binding EGF-related peptides in proliferation and apoptosis of activated ras-stimulated intestinal cells. Int J Cancer 73,917923.[CrossRef][ISI][Medline]
Submitted on May 12, 2004; resubmitted on May 11, 2005; accepted on May 20, 2005.
|