The relative importance of the oligosaccharide units in human chorionic gonadotropin (CG) for LH/CG receptor activation in rat Leydig cells and mouse Leydig tumor cells

Loenen, H J van; Gelderen-Boele, S van; Flinterman, J F; Merz, W.E.; Rommerts, F. F. G.

doi:10.1677/joe.0.1470367

Cited by 12 publications

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“…1)). Since LH and hCG have previously shown to transmit their signal via G s and cAMP (25), we examined the role of cAMP-elevating agents on the ERK activity. Indeed, both 8-Br-cAMP, and forskolin, which activate adenylyl cyclase, significantly activated ERK phosphorylation in the rLHR-4 cells (data not shown), indicating that the hCG-induced ERK activation may be dependent on elevation of intracellular cAMP.…”

Section: Resultsmentioning

confidence: 99%

The ERK Signaling Cascade Inhibits Gonadotropin-stimulated Steroidogenesis

Seger¹,

Hanoch²,

Rosenberg

et al. 2001

Journal of Biological Chemistry

212

110

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The response of granulosa cells to luteinizing hormone (LH) and follicle-stimulating hormone (FSH) is mediated mainly by cAMP/protein kinase A (PKA) signaling. Notably, the activity of the extracellular signal-regulated kinase (ERK) signaling cascade is elevated in response to these stimuli as well. We studied the involvement of the ERK cascade in LH-and FSH-induced steroidogenesis in two granulosa-derived cell lines, rLHR-4 and rFSHR-17, respectively. We found that stimulation of these cells with the appropriate gonadotropin induced ERK activation as well as progesterone production downstream of PKA. Inhibition of ERK activity enhanced gonadotropin-stimulated progesterone production, which was correlated with increased expression of the steroidogenic acute regulatory protein (StAR), a key regulator of progesterone synthesis. Therefore, it is likely that gonadotropin-stimulated progesterone formation is regulated by a pathway that includes PKA and StAR, and this process is down-regulated by ERK, due to attenuation of StAR expression. Our results suggest that activation of PKA signaling by gonadotropins not only induces steroidogenesis but also activates down-regulation machinery involving the ERK cascade. The activation of ERK by gonadotropins as well as by other agents may be a key mechanism for the modulation of gonadotropin-induced steroidogenesis.Gonadotropic hormones, follicle-stimulating hormone (FSH) 1 and luteinizing hormone (LH), which are released from the pituitary, play a crucial role in controlling reproductive function in males and females. The pleotropic effects of gonadotropins are manifested in various cells of the reproductive system including LH and FSH in ovarian granulosa cells, LH in theca interna cells, FSH in testicular Sertoli cells, and LH in Leydig cells (1-3). One of the main effects of both LH and FSH on the ovary is the stimulation of the production of estradiol and progesterone, which play important roles in ovarian function and control of the reproductive cycle (reviewed in Ref. 4). The mechanisms involved in the regulation of progesterone production by ovarian granulosa cells have been characterized in detail. Gonadotropins exert their stimulatory activity via interaction with specific seven-transmembrane receptors, the LH receptor and FSH receptor. Upon binding of the gonadotropins, both receptors stimulate the G s protein, which activates the membrane-associated adenylyl cyclase, causing an elevation of intracellular cAMP (5). This cyclic nucleotide serves as a second messenger for the up-regulation of the steroidogenic acute regulatory protein (StAR) and the cytochrome P450 (P450scc) enzyme system (reviewed in Refs. 6 and 7).Activation of alternative signaling pathways by the gonadotropin receptors was described in the last decade, including calcium ion mobilization, activation of the phosphoinositol pathway, and stimulation of chloride ion influx (reviewed in Ref. 8). However, these gonadotropin-induced signaling processes were not previously implicated in the modulation of s...

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Section: Resultsmentioning

confidence: 99%

The ERK Signaling Cascade Inhibits Gonadotropin-stimulated Steroidogenesis

Seger¹,

Hanoch²,

Rosenberg

et al. 2001

Journal of Biological Chemistry

212

110

View full text Add to dashboard Cite

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“…The effect of LH on ERK activity was essentially the same as that of hCG under all conditions examined (data not shown). Deglycosylated hCG (dghCG), which has previously been reported to maintain the same affinity for binding to the LH-receptor as the intact hormone but retains only a residual activity for stimulation of steroidogenesis [ 26 ], also caused activation of ERK. However, this activation was significantly lower than that achieved by the intact hormone (2.5-fold activation 20 min after dghCG treatment as compared to 4.5-fold 20 min after hCG treatment ( Figure 1 )).…”

Section: Resultsmentioning

confidence: 99%

“…However, this activation was significantly lower than that achieved by the intact hormone (2.5-fold activation 20 min after dghCG treatment as compared to 4.5-fold 20 min after hCG treatment ( Figure 1 )). Since LH and hCG have previously shown to transmit their signal via Gs and cAMP [ 26 ], we examined the role of cAMP-elevating agents on the ERK activity. Indeed, both 8-Br-cAMP, and forskolin, which activates adenylyl cyclase, significantly activated ERK phosphorylation in the rLHR-4 cells (data not shown), indicating that the hCG-induced ERK activation may be dependent on elevated cAMP.…”

Section: Resultsmentioning

confidence: 99%

The ERK Signaling Cascade Inhibits Gonadotropin-Stimulated Steroidogenesis

Seger¹,

Hanoch²,

Rosenberg³

et al. 2023

J Biotechnol Biomed

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The response of granulosa cells to Luteinizing Hormone (LH) and Follicle- Stimulating Hormone (FSH) is mediated mainly by cAMP/protein kinase A (PKA) signaling. Notably, the activity of the extracellular signal-regulated kinase (ERK) signaling cascade is elevated in response to these stimuli as well. We studied the involvement of the ERK cascade in LH- and FSH-induced steroidogenesis in two granulosa-derived cell lines, rLHR-4 and rFSHR-17, respectively. We found that stimulation of these cells with the appropriate gonadotropin induced ERK activation as well as progesterone production downstream of PKA. Inhibition of ERK activity enhanced gonadotropin-stimulated progesterone production, which was correlated with increased expression of the Steroidogenic Acute Regulatory Protein (StAR), a key regulator of progesterone synthesis. Therefore, it is likely that gonadotropin-stimulated progesterone formation is regulated by a pathway that includes PKA and StAR, and this process is down-regulated by ERK, due to attenuation of StAR expression. Our results suggest that activation of PKA signaling by gonadotropins not only induces steroidogenesis but also activates down-regulation machinery involving the ERK cascade. The activation of ERK by gonadotropins as well as by other agents may be a key mechanism for the modulation of gonadotropin-induced steroidogenesis.

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“…By measuring this immediate end product of cholesterol side-chain cleavage activity, we were able to measure the true rate of steroidogenesis in rat Leydig cells without complications of steroid metabolism. In a study on LH receptor activation by different hCG preparations and using MA-10 cells, we found that the measured biological activity of the various hCG preparations depended on the type of RIA (for progesterone or for pregnenolone) used for measuring steroid production (12). We suggested that the discrepancies between the results of the two assays could result from progesterone metabolism.…”

mentioning

confidence: 97%

Implications of Progesterone Metabolism in MA-10 Cells for Accurate Measurement of the Rate of Steroidogenesis

Rommerts¹

2001

Endocrinology

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In virtually all studies with MA-10 cells, progesterone RIAs have been used to measure steroid synthesis. To test whether progesterone is a stable end product, we investigated the metabolism of added tritiated progesterone and pregnenolone in MA-10 cells over a period of 3 h. Steroids were then extracted, separated by HPLC, and identified by GC/MS. We found that more than 70% of radiolabeled steroids were converted to at least five different metabolites. A major metabolite (40%) was 5 alpha-pregnan-3 alpha or 3 beta-ol-20one. Similar studies, using radiolabeled T, demonstrated conversion to dihydrotestosterone and two forms of 5 alpha-androstane-diols. These data indicate the presence of active 5 alpha-reductase and 3 alpha- and/or 3 beta-hydroxysteroid dehydrogenase activities in MA-10 cells. Because these results suggest that progesterone is an unstable end product, to gauge the level of active metabolism, we incubated cells in the presence of inhibitors of pregnenolone metabolism and assessed pregnenolone levels by RIA. We discovered that basal levels of steroidogenesis in MA-10 cells were considerably higher than previously estimated. Moreover, dibutyryl cAMP-stimulated steroid production was linear over more than 13 h, in contrast to previous findings that measured progesterone levels. Other consequences of inaccurate assessment of steroidogenic activity in MA-10 cells because of the application of the progesterone assay are discussed.

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The relative importance of the oligosaccharide units in human chorionic gonadotropin (CG) for LH/CG receptor activation in rat Leydig cells and mouse Leydig tumor cells

Cited by 12 publications

References 0 publications

The ERK Signaling Cascade Inhibits Gonadotropin-stimulated Steroidogenesis

The ERK Signaling Cascade Inhibits Gonadotropin-stimulated Steroidogenesis

The ERK Signaling Cascade Inhibits Gonadotropin-Stimulated Steroidogenesis

Implications of Progesterone Metabolism in MA-10 Cells for Accurate Measurement of the Rate of Steroidogenesis

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