Role of phosphoprotein phosphatases in the corpus luteum: I Identification and characterisation of serine/threonine phosphoprotein phosphatases in isolated rat luteal cells

1996 ◽  
Vol 150 (2) ◽  
pp. 205-211 ◽  
Author(s):  
S L Ford ◽  
D R E Abayasekara ◽  
S J Persaud ◽  
P M Jones
Keyword(s):  
Polyclonal Antibodies ◽  
Luteal Cell ◽  
Luteal Cells ◽  
Cell Functions ◽  
Phosphoprotein Phosphatases ◽  
Sds Page ◽  
Molecular Masses ◽  
Dose Dependent Decrease

Abstract Although the role of protein kinases and phosphorylation in steroidogenesis has received much attention, very little is known about the activities of phosphoprotein phosphatases (PP) and dephosphorylation in steroidogenic tissues. The aims of the present study were therefore to identify which of those serine/threonine PPs more commonly involved in intracellular signalling are expressed in rat luteal cells; to quantify, in vitro, the effects of inhibitors on PP activity extracted from purified rat luteal cells; and to measure the effects of PP inhibitors on the phosphorylation of endogenous luteal cell proteins. Polyclonal antibodies raised against the catalytic subunits of PP types 1 and 2A, and a monoclonal antibody raised against the Ca2+-binding subunit of PP2B, were used to identify immunoreactive proteins that migrated on SDS-PAGE with approximate molecular masses of 37, 34 and 16 kDa, corresponding well with the reported molecular mass of PP1, PP2A and PP2B respectively. Five selective inhibitors of PP1/PP2A: okadaic acid, calyculin A, cantharidin, tautomycin and microcystin-RR, each caused a dose-dependent decrease in the activity of PPs in luteal cell homogenates, and also enhanced 32P incorporation into numerous luteal cell proteins; most notably, proteins with approximate molecular masses of 20 and 22 kDa. The results of this study suggest that PPs may play an important role in the regulation of rat luteal cell functions. Journal of Endocrinology (1996) 150, 205–211

Functional luteolysis in response to hydrogen peroxide in human luteal cells

1995 ◽  
Vol 147 (1) ◽  
pp. 177-182 ◽  
Author(s):  
M Vega ◽  
I Carrasco ◽  
T Castillo ◽  
J L Troncoso ◽  
L A Videla ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Cultures ◽  
Specific Binding ◽  
Luteal Cell ◽  
Luteal Cells ◽  
Dose Dependent Decrease ◽  
Dose Dependent ◽  
Human Corpus Luteum

Abstract To evaluate the effect of reactive oxygen species in human corpus luteum function, we investigated whether hydrogen peroxide (H2O2) affects the in vitro luteal cell production of steroids. H2O2 treatment (1·0–100 μm) of mid and late luteal cell cultures elicited a dose-dependent decrease in basal progesterone production. However, treatment of mid luteal cells with a low concentration of H2O2 0·01 μm) significantly stimulated progesterone secretion (P<0·05). In addition, H2O2 (100 μm) markedly inhibited human chorionic gonadotropin (hCG)-stimulated progesterone and estradiol secretion. cAMP production was enhanced (2·4-fold, P<0·05) by hCG treatment of luteal cells. The addition of H2O2 (0·1–100 μm) to hCG-stimulated luteal cell cultures elicited a decrease in cAMP concentration (P<0·05) and in the specific binding of radiolabeled hCG by luteal cells. Progesterone and estradiol production stimulated by dibutyryl cAMP were significantly inhibited by H2O2 (P<0·05). These findings suggest that H2O2 interferes with basal steroid production and, in hCG-stimulated conditions, it may inactivate the gonadotropin–receptor complex. The anti-steroidogenic action of H2O2 therefore raises the possibility of a modulatory role of H2O2 in human luteal steroidogenesis. Journal of Endocrinology (1995) 147, 177–182

scholarly journals HIF-1α Activation Promotes Luteolysis by Enhancing ROS Levels in the Corpus Luteum of Pseudopregnant Rats

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zonghao Tang ◽  
Jiajie Chen ◽  
Zhenghong Zhang ◽  
Jingjing Bi ◽  
Renfeng Xu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Corpus Luteum ◽  
Cell Apoptosis ◽  
In Vitro Study ◽  
Luteal Cell ◽  
Independent Manner ◽  
Luteal Regression ◽  
Luteal Cells

The increase of oxidative stress is one of the important characteristics of mammalian luteal regression. Previous investigations have revealed the essential role of reactive oxygen species (ROS) in luteal cell death during luteolysis, while it is unknown how ROS is regulated in this process. Considering the decrease of blood flow and increase of PGF2α during luteolysis, we hypothesized that the HIF-1α pathway may be involved in the regulation of ROS in the luteal cell of the late corpus luteum (CL). Here, by using a pseudopregnant rat model, we showed that the level of both HIF-1α and its downstream BNIP3 was increased during luteal regression. Consistently, we observed the increase of autophagy level during luteolysis, which is regulated in a Beclin1-independent manner. Comparing with early (Day 7 of pseudopregnancy) and middle CL (Day 14), the level of ROS was significantly increased in late CL, indicating the contribution of oxidative stress in luteolysis. Inhibition of HIF-1α by echinomycin (Ech), a potent HIF-1α inhibitor, ameliorated the upregulation of BNIP3 and NIX, as well as the induction of autophagy and the accumulation of ROS in luteal cells on Day 21 of pseudopregnancy. Morphologically, Ech treatment delayed the atrophy of the luteal structure at the late-luteal stage. An in vitro study indicated that inhibition of HIF-1α can also attenuate PGF2α-induced ROS and luteal cell apoptosis. Furthermore, the decrease of cell apoptosis can also be observed by ROS inhibition under PGF2α treatment. Taken together, our results indicated that HIF-1α signaling is involved in the regression of CL by modulating ROS production via orchestrating autophagy. Inhibition of HIF-1α could obviously hamper the apoptosis of luteal cells and the process of luteal regression.

scholarly journals Role of gap junctions in regulation of progesterone secretion by ovine luteal cells in vitro

Reproduction ◽  
2007 ◽  
Vol 133 (3) ◽  
pp. 641-651 ◽  
Author(s):  
Ewa Borowczyk ◽  
Mary Lynn Johnson ◽  
Jerzy J Bilski ◽  
Magda A Bilska ◽  
Dale A Redmer ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Mrna Expression ◽  
Estrous Cycle ◽  
Luteal Cell ◽  
Gap Junctional Intercellular Communication ◽  
Luteal Cells ◽  
Progesterone Secretion ◽  
Cx43 Mrna

To evaluate the role of gap junctions in the regulation of progesterone secretion, two experiments were conducted. In Experiment 1, luteal cells obtained on days 5, 10, and 15 were cultured overnight at densities of 50×103, 100×103, 300×103, and 600×103cells/dish in medium containing: (1) no treatment (control), (2) LH, or (3) dbcAMP. In Experiment 2, luteal cells from days 5 and 10 of the estrous cycle were transfected with siRNA, which targeted the connexin (Cx) 43 gene. In Experiment 1, progesterone secretion, Cx43 mRNA expression, and the rates of gap junctional intercellular communication (GJIC), were affected by the day of the estrous cycle, cell density, and treatments (LH or dbcAMP). The changes in progesterone secretion were positively correlated with the changes in Cx43 mRNA expression and the rates of GJIC. Cx43 was detected on the luteal cell borders in every culture, and luteal cells expressed 3β-hydroxysteroid dehydrogenase. In Experiment 2, twoCx43gene-targeted sequences decreased Cx43 mRNA expression and progesterone production by luteal cells. The changes in Cx43 mRNA expression were positively correlated with changes in progesterone concentration in media. Thus, our data demonstrate a relationship between gap junctions and progesterone secretion that was supported by (1) the positive correlations between progesterone secretion and Cx43 mRNA expression and GJIC of luteal cells and (2) the inhibition of Cx43 mRNA expression by siRNA that resulted in decreased production of progesterone by luteal cells. This suggests that gap junctions may be involved in the regulation of steroidogenesis in the ovine corpus luteum.

Role of phosphoprotein phosphatases in the corpus luteum: II Control of progesterone secretion by isolated rat luteal cells

1996 ◽  
Vol 150 (2) ◽  
pp. 213-221 ◽  
Author(s):  
D R E Abayasekara ◽  
S L Ford ◽  
S J Persaud ◽  
P M Jones
Keyword(s):  
Cyclic Amp ◽  
Okadaic Acid ◽  
Luteal Cell ◽  
Steroidogenic Enzymes ◽  
Luteal Cells ◽  
Phosphoprotein Phosphatases ◽  
Progesterone Secretion ◽  
Dependent Inhibition ◽  
And Function

Abstract The key role of protein kinases and protein phosphorylation in the regulation of luteal steroidogenesis is well documented. However the role of phosphoprotein phosphatases (PP) and dephosphorylation in the regulation of luteal cell progesterone secretion is as yet unknown. We have recently demonstrated the presence and activity of PP1 and PP2A in rat luteal cells and the present study was undertaken to determine the consequences of inhibiting PP activity in terms of progesterone secretion. Three structurally dissimilar inhibitors of PP1/2A, okadaic acid, calyculin A and cantharidin each caused a dose-dependent inhibition of LH-induced progesterone secretion without affecting cyclic AMP accumulation. The less potent derivative of okadaic acid, norokadaone, had no effect on either parameter, suggesting that the inhibitory actions on progesterone secretion are due to their specific actions on PP activity and that this inhibition occurs principally at a locus which is distal to the generation of cyclic AMP. In contrast to the inhibitory effects of PP1/2A inhibitors on progesterone biosynthesis, a PP2B inhibitor, cypermethrin, had no effect on LH-stimulated steroidogenesis. The three PP1/2A inhibitors also caused a concentration-dependent inhibition of dibutyryl cyclic AMP-stimulated progesterone secretion. However, none of the inhibitors affected 22R-hydroxycholesterol-supported steroidogenesis, clearly demonstrating that the inhibitors did not interfere with the activity of steroidogenic enzymes. These results suggest that cycles of phosphorylation/dephosphorylation of specific proteins are required for the sustained production of progesterone. Whilst the precise location and function of putative PP substrates is uncertain, the present results indicate that they are involved in regulating the availability of free cholesterol to steroidogenic enzymes within mitochondria. Journal of Endocrinology (1996) 150, 213–221

scholarly journals Role of maltase in the utilization of sucrose by Candida albicans

1993 ◽  
Vol 291 (3) ◽  
pp. 765-771 ◽  
Author(s):  
P R Williamson ◽  
M A Huber ◽  
J E Bennett
Keyword(s):  
Candida Albicans ◽  
Intracellular Localization ◽  
Cross Reactivity ◽  
Neutral Sugar ◽  
Sequence Specificity ◽  
Western Blots ◽  
Sds Page ◽  
Molecular Masses ◽  
Kinetics Of

Two isoenzymes of maltase (EC 3.2.1.20) were purified to homogeneity from Candida albicans. Isoenzymes I and II were found to have apparent molecular masses of 63 and 66 kDa on SDS/PAGE with isoelectric points of 5.0 and 4.6 respectively. Both isoenzymes resembled each other in similar N-terminal sequence, specificity for the alpha(1-−>4) glycosidic linkage and immune cross-reactivity on Western blots using a maltase II antigen-purified rabbit antibody. Maltase was induced by growth on sucrose whereas beta-fructofuranosidase activity could not be detected under similar conditions. Maltase I and II were shown to be unglycosylated enzymes by neutral sugar assay, and more than 90% of alpha-glucosidase activity was recoverable from spheroplasts. These data, in combination with other results from this laboratory [Geber, Williamson, Rex, Sweeney and Bennett (1992) J. Bacteriol. 174, 6992-6996] showing lack of a plausible leader sequence in genomic or mRNA transcripts, suggest an intracellular localization of the enzyme. To establish further the mechanism of sucrose assimilation by maltase, the existence of a sucrose-inducible H+/sucrose syn-transporter was demonstrated by (1) the kinetics of sucrose-induced [14C]sucrose uptake, (2) recovery of intact [14C]sucrose from ground cells by t.l.c. and (3) transport of 0.83 mol of H+/mol of [14C]sucrose. In total, the above is consistent with a mechanism whereby sucrose is transported into C. albicans to be hydrolysed by an intracellular maltase.

scholarly journals Control of Steroidogenesis in Small and Large Bovine Luteal. Cells

1987 ◽  
Vol 40 (3) ◽  
pp. 331 ◽  
Author(s):  
William Hansel ◽  
Hector W Alila ◽  
Joseph P Dowd ◽  
Xiangzhong Yang
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Corpus Luteum ◽  
Luteal Cell ◽  
Lipoxygenase Pathway ◽  
Luteal Cells ◽  
Kinase C ◽  
Bovine Corpus Luteum ◽  
Progesterone Synthesis

Evidence was cited to show that: (1) prostacyclin (PGI2) plays a luteotrophic role in the bovine corpus luteum and that products of the lipoxygenase pathway of arachidonic acid metabolism, especially 5-hydroxyeicosatetraenoic acid play luteolytic roles; (2) oxytocin of luteal cell origin plays a role in development, and possibly in regression, of the bovine corpus luteum; and (3) luteal cells arise from two sources; the characteristic small luteal cells at all stages of the o~strous cycle and pregnancy are of theca cell origin; the large cells are of granulosa cell origin early in the cycle, but a population of theca-derived large cells appears later in the cycle. Results of in vitro studies with total dispersed cells and essentially pure preparations of large and small luteal cells indicate that : (1) the recently described Ca2+ -polyphosphoinositol-protein kinase C second messenger system is involved in progesterone synthesis in the bovine corpus luteum; (2) activation of protein kinase C is stimulatory to progesterone synthesis in the small luteal cells; (3) activation of protein kinase C has no effect on progesterone synthesis in the large luteal cells; and (4) protein kinase C exerts its luteotrophic effect in total cell preparations, in part at least, by stimulating the production of prostacyclin. The protein kinase C system may cause down regulation of LH receptors in the large cells.

scholarly journals Human chorionic gonadotropin-induced amphiregulin stimulates aromatase expression in human granulosa-lutein cells: a mechanism for estradiol production in the luteal phase

2019 ◽  
Vol 34 (10) ◽  
pp. 2018-2026 ◽  
Author(s):  
Lanlan Fang ◽  
Yiping Yu ◽  
Yiran Li ◽  
Sijia Wang ◽  
Ruizhe Zhang ◽  
...  
Keyword(s):  
Menstrual Cycle ◽  
Follicular Fluid ◽  
Natural Science ◽  
Luteal Phase ◽  
Small Sample ◽  
Luteal Cell ◽  
Aromatase Expression ◽  
Protein Levels

Abstract STUDY QUESTION Does amphiregulin (AREG), the most abundant and important epidermal growth factor receptor (EGFR) ligand in the follicular fluid, regulate aromatase expression in human granulosa-lutein (hGL) cells? SUMMARY ANSWER AREG mediates the hCG-induced up-regulation of aromatase expression and estradiol (E2) production in hGL cells. WHAT IS KNOWN ALREADY AREG expression and secretion are rapidly induced by hCG in hGL cells and mediate physiological functions of LH/hCG in the ovary. EGFR protein is expressed in follicles not only in the pre-ovulatory phase but also throughout the luteal phase of the menstrual cycle. After the LH surge, the human corpus luteum secretes high levels of E2, which regulates various luteal cell functions. Aromatase is an enzyme responsible for a key step in the biosynthesis of E2. However, whether AREG regulates aromatase expression and E2 production in hGL cells remains unexplored. STUDY DESIGN, SIZE, DURATION This study is an experimental study performed over a 1-year period. In vitro investigations examined the role of AREG in the regulation of aromatase expression and E2 production in primary hGL cells. PARTICIPANTS/MATERIALS, SETTING, METHODS Primary hGL cells were obtained from women undergoing IVF treatment in an academic research center. Aromatase mRNA and protein levels were examined after exposure of hGL cells to recombinant human AREG, hCG or LH. The EGFR tyrosine kinase inhibitor AG1478, PI3K inhibitor LY294002 and siRNAs targeting EGFR, LH receptor, StAR and AREG were used to verify the specificity of the effects and to investigate the underlying molecular mechanisms. Reverse transcription quantitative real-time PCR (RT-qPCR) and western blot were used to measure the specific mRNA and protein levels, respectively. Follicular fluid and serum were collected from 65 infertile women during IVF treatment. Pearson’s correlation analysis was performed to examine the correlation coefficient between two values. MAIN RESULTS AND THE ROLE OF CHANCE Treatment of hGL cells with AREG-stimulated aromatase expression and E2 production. Using pharmacological inhibitors and specific siRNAs, we revealed that AREG-stimulated aromatase expression and E2 production via EGFR-mediated activation of the protein kinase B (AKT) signaling pathway. In addition, inhibition of EGFR activity and AREG knockdown attenuated hCG-induced up-regulation of aromatase expression and E2 production. Importantly, the protein levels of AREG in the follicular fluid were positively correlated with the E2 levels in serum after 2 days of oocyte pick-up and in the follicular fluid of IVF patients. LARGE-SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION The in vitro setting of this study is a limitation that may not reflect the real intra-ovarian microenvironment. Clinical data were obtained from a small sample size. WIDER IMPLICATIONS OF THE FINDINGS Our results provide the first evidence that hCG-induced AREG contributes to aromatase expression and E2 production in the luteal phase of the menstrual cycle. A better understanding of the hormonal regulation of female reproductive function may help to develop new strategies for the treatment of clinical infertility. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the National Natural Science Foundation of China for Young Scientists (81601253), the specific fund of clinical medical research of Chinese Medical Association (16020160632) and the Foundation from the First Affiliated Hospital of Zhengzhou University for Young Scientists to Lanlan Fang. This work was also supported by an operating grant from the National Natural Science Foundation of China (81820108016) to Ying-Pu Sun. All authors declare no conflict of interest.

Immunotoxins up to the present day

1989 ◽  
Vol 9 (2) ◽  
pp. 139-156 ◽  
Author(s):  
Francis A. Drobniewski
Keyword(s):  
Clinical Studies ◽  
Polyclonal Antibodies ◽  
Cell Binding ◽  
Ricin A Chain ◽  
Future Role ◽  
A Chain ◽  
Ricin A

Immunotoxins consist of monoclonal or polyclonal antibodies conjugated to bacterial or plant toxins. The toxins used are typically of the A-B type in which a toxic A chain is coupled to a B chain responsible for cell binding and facilitation of A chain entry into the cytosol. Two broad strategies have been followed: coupling intact toxins, or A chains alone, to antibodies. This review examines current progress in in vitro and in vivo research, including recent clinical studies, concentrating principally on ricin or ricin A chain conjugates. The future role of conjugates using membrane-acting toxins, immunolysins, is also discussed.

Cellular basis of luteal steroidogenesis in the human ovary

1989 ◽  
Vol 122 (1) ◽  
pp. 303-NP ◽  
Author(s):  
B. Fisch ◽  
R. A. Margara ◽  
R. M. L. Winston ◽  
S. G. Hillier
Keyword(s):  
Luteal Phase ◽  
Culture System ◽  
Direct Action ◽  
Cellular Level ◽  
Luteal Cell ◽  
Aromatase Activity ◽  
Vitro Fertilization ◽  
Luteal Cells ◽  
Expected Time

ABSTRACT A primary monolayer cell culture system was developed to investigate human corpus luteum (CL) function in vitro. Steroidogenic cells were isolated by collagenase dispersal and Percoll density-gradient fractionation from CLs enucleated at progressive stages of the luteal phase (tubal surgery patients). 'Pure' granulosa-lutein cells were aspirated from ovulatory follicles at mid-cycle (in-vitro fertilization patients). The steroidogenic capacity (progesterone/20α-dihydroprogesterone biosynthesis and aromatase activity) of isolated luteal cells was assessed in relation to CL development. Basal luteal cell steroidogenesis was maximal at around the expected time of ovulation and declined with CL age during the luteal phase. Conversely, human chorionic gonadotrophin (hCG)-responsive steroidogenesis was initially undetectable but developed as the luteal phase progressed. These results show that luteal cell steroidogenesis becomes increasingly dependent upon gonadotrophic support with CL age. This is evidence that functional luteolysis in human ovaries (1) is pre-programmed to occur at the cellular level, (2) is initiated automatically at the time of ovulation and (3) is reversed at the time of CL 'rescue' in early pregnancy by the direct action of trophoblastic hCG on steroidogenic luteal cells. The culture system described should be of value in further defining the control of human CL form and function at the cellular level. Journal of Endocrinology (1989) 122, 303–311

scholarly journals Role of TRPV channels in regulating various pancreatic β-cell functions: Lessons from in vitro studies

2017 ◽  
Vol 11 (1) ◽  
pp. 9-15
Author(s):  
Marek Skrzypski ◽  
Maria Billert ◽  
Stefan Mergler ◽  
Noushafarin Khajavi ◽  
Krzysztof W. Nowak ◽  
...  
Keyword(s):  
Pancreatic Β Cell ◽  
Β Cell ◽  
Cell Functions ◽  
Trpv Channels
Sign in / Sign up

Export Citation Format

Share Document