Epidermal Growth Factor Enhances Expression of Connexin 43 Protein in Cultured Porcine Preantral Follicles1

Bolamba, D; Floyd, Anthony A.; McGlone, John J.; Lee, Vaughan H.

doi:10.1095/biolreprod67.1.154

Cited by 28 publications

(20 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…EGF has been shown to positively or negatively regulate Cx43 expression depending on the cell type in question. Stimulatory effects of EGF on Cx43 have been described in porcine preantral follicles, rat granulosa cells, human kidney epithelial cells, human neural progenitor cells, and glioblastoma cells (Rivedal et al, ; Bolamba et al, ; Kennedy et al, ; Lemcke and Kuznetsov, ; Munoz et al, ); whereas suppressive effects have been observed in rat astrocytes and liver epithelial cells (Ueki et al, ; Leithe and Rivedal, ). In keeping with the cell context‐dependent regulation of Cx43 by EGF, multiple signaling pathways have been variably described to mediate both positive and negative effects.…”

Section: Discussionmentioning

confidence: 99%

EGF‐Induced Connexin43 Negatively Regulates Cell Proliferation in Human Ovarian Cancer

Qiu

Cheng

Klausen

et al. 2015

Journal Cellular Physiology

View full text Add to dashboard Cite

Connexin43 (Cx43) has been shown to regulate cell proliferation and its downregulation is correlated with poor prognosis and survival in several types of human cancer. Cx43 expression levels are frequently downregulated in human ovarian cancer, suggesting a potential role for Cx43 in regulating the progression of this disease. Epidermal growth factor (EGF) is a well-characterized hormone that stimulates ovarian cancer cell proliferation. Although EGF is able to regulate Cx43 expression in other cell types, it is unclear whether EGF can regulate Cx43 expression in ovarian cancer cells. Additionally, it remains unknown whether Cx43 is involved in EGF-stimulated ovarian cancer cell proliferation. In the present study, we demonstrate that treatment with EGF upregulates Cx43 expression in two ovarian cancer cell lines, SKOV3 and OVCAR4. Although treatment with EGF activates both ERK1/2 and Akt signaling pathways, pharmacological inhibition and siRNA-mediated knockdown suggest that only the activation of Akt1 is required for EGF-induced Cx43 upregulation. Functionally, Cx43 knockdown enhanced basal and EGF-induced cell proliferation, whereas the proliferative effects of EGF were reduced by Cx43 overexpression. Co-treatment with the gap junction inhibitor carbenoxolone did not alter the suppressive effects of Cx43 overexpression on EGF-induced cell proliferation, suggesting a gap junction-independent mechanism. This study reveals an important role for Cx43 as a negative regulator of EGF-induced human ovarian cancer cell proliferation.

show abstract

Section: Discussionmentioning

confidence: 99%

EGF‐Induced Connexin43 Negatively Regulates Cell Proliferation in Human Ovarian Cancer

Qiu

Cheng

Klausen

et al. 2015

Journal Cellular Physiology

View full text Add to dashboard Cite

show abstract

“…In the rat, several studies demonstrate that the connexin 43 gap junction protein is present in multiphosphorylated forms: the 43-kDa band represents the nonphosphorylated form, while the bands with the slightly retarded electrophoretic mobility represent the phosphorylated forms [57][58][59]. In porcine, immunoblot analysis revealed the presence of two immunoreactive bands of 43 and 45 kDa [60,61] or three bands of 43, 45, and 47 kDa [42]. The 43-kDa band is a nonphosphorylated band, whereas the 45-and 47-kDa bands are phosphorylated forms of this protein.…”

Section: Discussionmentioning

confidence: 99%

Effect of Growth Hormone (GH) on In Vitro Nuclear and Cytoplasmic Oocyte Maturation, Cumulus Expansion, Hyaluronan Synthases, and Connexins 32 and 43 Expression, and GH Receptor Messenger RNA Expression in Equine and Porcine Species1

Marchal

Caillaud

Martoriati

et al. 2003

Biology of Reproduction

View full text Add to dashboard Cite

The aim of this study was to investigate the role of growth hormone (GH) on in vitro cumulus expansion and oocyte maturation in equine and porcine cumulus-oocyte complexes (COCs), and to approach its way of action. Equine COCs were cultured in a control medium (TCM199, 5 mg/ml BSA, 1 g/ml estradiol, and antibiotics) supplemented with either 0.5 g/ml equine GH or 5 g/ml equine LH. Porcine COCs were cultured in a basal medium (TCM199 with 570 M cysteamine) supplemented with 0, 0.1, 0.5, or 1 g/ml porcine GH or in a control medium (basal medium with 10 ng/ml epidermal growth factor and 400 ng/ml FSH) supplemented with 0 or 0.5 g/ml porcine GH. After culture, cumulus expansion and nuclear stage were assessed. The cytoplasmic maturation of porcine oocytes was evaluated by in vitro fertilization and development for 7 days. The modifications of the expression of proteins implicated in cumulus expansion were analyzed in equine COCs by SDS-PAGE with antibodies against connexins 32 and 43 and hyaluronan synthases (Has) 1, 2, and 3. The expression of GH receptor mRNA was studied in oocytes and cumulus cells of the two species using reverse transcription-polymerase chain reaction with specific primers. The addition of GH in maturation medium increased cumulus expansion in equine but not porcine COCs. It improved nuclear maturation in equine and porcine, but had no effect on porcine fertilization and embryo development. The GH receptor mRNA was detected in equine and porcine oocytes and cumulus cells. GH did not influence the expression of Has 1, Has 3, and connexin 43 in equine cumulus cells. cumulus cells, gamete biology, growth hormone, oocyte development, ovum INTRODUCTIONGonadotropins are the major regulators of ovarian function. In the last few years, however, there has been evidence that growth factors and metabolic hormones are also involved in ovarian regulation. The role of growth hormone (GH) in ovarian functions, follicular growth, and steroidogenesis is well known [1, 2 for review], and some evidence shows a positive effect of GH on oocyte maturation.

show abstract

“…Treatment of a kidney epithelial cell line with EGF for 2-3 h was reported to stimulate the upregulation of gap junctional communication, which may be related to the synthesis or transport of Cx43 (Vikhamar, Rivedal, Mollerup, & Sanner, 1998). EGF was also found recently to increase the expression of Cx43 protein in porcine granulosa cells by two to five-fold (Bolamba, Floyd, McGlone, & Lee, 2002). This change occurred in the absence of changes in Cx43 phosphorylation and may be involved in the regulation of early folliculogenesis.…”

Section: Receptor Protein Tyrosine Kinases-in Many Cases Activation mentioning

confidence: 94%

The effects of connexin phosphorylation on gap junctional communication

Lampe

Lau

2004

The International Journal of Biochemistry & Cell Biology

545

463

View full text Add to dashboard Cite

Gap junctions are specialized membrane domains composed of collections of channels that directly connect neighboring cells providing for the cell-to-cell diffusion of small molecules, including ions, amino acids, nucleotides, and second messengers. Vertebrate gap junctions are composed of proteins encoded by the "connexin" gene family. In most cases examined, connexins are modified posttranslationally by phosphorylation. Phosphorylation has been implicated in the regulation of gap junctional communication at several stages of the connexin "lifecycle", such as the trafficking, assembly/disassembly, degradation, as well as, the gating of gap junction channels. Since connexin43 (Cx43) is widely expressed in tissues and cell lines, we understand the most about how it is regulated, and thus, connexin43 phosphorylation is a major focus of this review. Recent reports utilizing new methodologies combined with the latest genome information have shown that activation of several kinases including protein kinase A, protein kinase C, p34 cdc2 /cyclin B kinase, casein kinase 1, mitogen-activated protein (MAP) kinase and pp60 src kinase can lead to phosphorylation at 12 of the 21 serine and two of the six tyrosine residues in the C-terminal region of connexin43. In several cases, use of site-directed mutants of these sites have shown that these specific phosphorylation events can be linked to changes in gap junctional communication.

show abstract

Epidermal Growth Factor Enhances Expression of Connexin 43 Protein in Cultured Porcine Preantral Follicles1

Cited by 28 publications

References 59 publications

EGF‐Induced Connexin43 Negatively Regulates Cell Proliferation in Human Ovarian Cancer

EGF‐Induced Connexin43 Negatively Regulates Cell Proliferation in Human Ovarian Cancer

Effect of Growth Hormone (GH) on In Vitro Nuclear and Cytoplasmic Oocyte Maturation, Cumulus Expansion, Hyaluronan Synthases, and Connexins 32 and 43 Expression, and GH Receptor Messenger RNA Expression in Equine and Porcine Species1

The effects of connexin phosphorylation on gap junctional communication

Contact Info

Product

Resources

About