Biol Reprod
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Haisenleder, D.J.
Right arrow Articles by Marshall, J.C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Haisenleder, D.J.
Right arrow Articles by Marshall, J.C.
Agricola
Right arrow Articles by Haisenleder, D.J.
Right arrow Articles by Marshall, J.C.
Biology of Reproduction 65, 1789-1793 (2001)
© 2001 Society for the Study of Reproduction, Inc.

Regular Article

Gonadotropin Subunit Transcriptional Responses to Calcium Signals in the Rat: Evidence for Regulation by Pulse Frequency1

D.J. Haisenleder2,a, L.J. Workmana, L.L. Burgera, K.W. Aylora, A.C. Dalkina, and J.C. Marshalla

a Division of Endocrinology, Department of Medicine, and the Center for Research in Reproduction, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Alterations in the frequency of calcium influx signals to rat pituitary cells can regulate the expression of gonadotropin subunit mRNAs in a differential manner, producing effects that are similar to those previously found for GnRH. The present study was conducted to investigate whether this reflects a transcriptional response to calcium pulse frequency, as determined by alterations in primary transcript (PT) expression. Perifused rat pituitary cells were given pulses of the calcium channel-activator Bay K 8644 (BK; with 10 mM KCl in the injectate) for 6 h. The response to alterations in pulse dose was examined by giving pulses of 1, 3, or 10 µM BK at 60-min intervals. Maximal increases in LHß and FSHß PTs were obtained with the 3-µM BK pulse dose and with the 10-µM dose for {alpha}. To investigate the effect of calcium pulse frequency, 3-µM BK pulses were given at intervals of 15, 60, or 180 min. Alpha PT was selectively stimulated by 15-min pulses and LHß by 15- and 60-min pulses of BK. In contrast, FSHß PT was maximally stimulated by the slower, 180-min pulse interval. These findings reveal that pulsatile increases in intracellular calcium stimulate {alpha}, LHß, and FSHß transcription in a differential manner. Thus, intermittent changes in intracellular calcium appear to be important in the transmission of GnRH pulse signals from the plasma membrane to the gene, and they may mediate the differential actions of pulse frequency on gonadotropin subunit gene expression.

calcium, gonadotropin-releasing hormone, mechanisms of hormone action, pituitary hormones, signal transduction


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Pulsatile GnRH regulates gonadotropin subunit ({alpha}, LHß, and FSHß) gene expression [1–3]. The results from both in vivo and in vitro studies reveal that the pattern of GnRH pulse signals (i.e., amplitude and frequency) can play a critical role in determining mRNA responses of various gonadotrope genes, including gonadotropin subunits, GnRH receptor (GnRH-R), follistatin, and activin (ßB) subunit [4–6]. Of note, GnRH pulse frequency regulates gonadotropin subunit gene expression in a differential manner, with {alpha} and LHß mRNAs maximally stimulated by faster pulses (15- to 30-min intervals) and FSHß by slower pulses (120- to 240-min intervals) [1]. Further studies have shown that the gonadotropin subunit response to GnRH pulse frequency is at the transcriptional level [2, 7]. However, the intracellular messengers responsible for transmitting frequency-dependent signals from the plasma membrane to the nucleus remain to be characterized.

The GnRH-R binding stimulates the activation of phospholipase C, resulting in a rise in intracellular calcium and activation of protein kinase C [8]. Activation of the GnRH-R also increases intracellular cAMP and activates various members of the mitogen-activated protein kinase (MAPK) family, including the extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 pathways [9–12]. Findings from recent studies suggest that specific members of the MAPK family regulate gonadotrope gene expression in a selective manner, with ERK stimulating {alpha}, FSHß, and GnRH-R mRNAs and JNK increasing rat LHß promoter activity [10, 13, 14].

Calcium has been implicated as a major component in the mechanism of action for GnRH [15]. Activation of the GnRH-R stimulates a transient rise in intracellular calcium due to release from intracellular storage pools and influx from L-type voltage-sensitive channels [8, 15]. We have previously shown that calcium plays an essential role in gonadotropin subunit mRNA responses to GnRH, and that pulsatile calcium signals (via pulses of the L-type channel-activator Bay K 8644 [BK]) are more effective in stimulating {alpha}, LHß, and FSHß mRNAs than continuous calcium [16]. More recent findings reveal that alterations in the frequency of calcium signals can regulate gonadotrope mRNA expression in a differential manner, producing effects similar to those observed for GnRH [1, 17]. However, the role played by calcium in regulating gonadotropin subunit transcription remains uncertain [13,18].

Thus, the present study was conducted to determine whether gonadotropin subunit mRNA responses to calcium pulse frequency reflect actions at the transcriptional level. To address this issue, we utilized recently characterized, quantitative reverse transcription-polymerase chain reaction (RT-PCR) assays to measure gonadotropin subunit primary transcripts (PTs) as a method to determine alterations in transcriptional activity. Compared to estimates of transcription using nuclear run-on assays, the enhanced sensitivity of these RT-PCR assays allows the assessment of transcriptional responses to specific treatments using the limited amount of RNA recoverable from rat pituitary cells in vitro.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
In Vitro Perifusion System

Adult, random cyclic, female rats were killed in accordance with the National Research Council's Guide for the Care and Use of Laboratory Animals (using procedures approved by the University of Virginia Animal Care and Use Committee). For each experiment, pituitaries from 36 adult female rats were pooled and dissociated in medium containing 0.35% (w/v) collagenase, 0.1% (w/v) hyaluronidase, and 0.01% (w/v) DNase. Following dissociation, the cell suspension was aliquoted into 12 culture wells (5–6 x 106 cells/well) containing 22-mm plastic coverslips coated with Matrigel (Becton Dickinson, Bedford, MA). The cells were cultured for 48 h before beginning each experiment. The in vitro procedure and culture medium constituents have been previously described [16]. To allow LHß mRNA expression in response to pulsatile GnRH, testosterone (at a concentration present during proestrus, 500 pg/ml [19]) was added during the last 24 h of plating and during perifusion. After plating, the coverslips were inserted into custom-made chambers and allowed to equilibrate for 1 h before treatment was initiated. The perifusion flow rate was 200 µl/min, and 100-µl pulses were administered over a 10-sec duration via Autosyringe pumps (model AS2C; Travenol Labs, Inc., Hooksett, NH).

Experimental Protocol

Perifusion chambers received pulses of BK plus potassium chloride (BK + KCl; peak chamber concentration, 1, 3, or 10 µM BK plus 10 mM KCl) at intervals of 15, 60, or 180 min for 6 h. This treatment paradigm is based on previous data showing that BK is more effective in stimulating pituitary secretion or mRNA responses in the presence of a threshold depolarization concentration of K in the medium [16]. Control groups received either vehicle pulses (0.2% [v/v] ethanol/medium) or pulses of GnRH (peak chamber concentration, 200 pM) every 60 min. This GnRH treatment protocol was based on previous experiments in our laboratory showing stimulation of {alpha}, LHß, and FSHß mRNAs. The LH and FSH secretory responses to pulse treatments were determined by collecting 10-min perifusate fractions over 60 min between 3 and 4 h of treatment. Studies were conducted as three to five separate experiments (12 chambers/experiment), with all treatment groups represented in each experiment (2–3 chambers/treatment per experiment). Ten minutes after the final pulse, the cells were recovered, total RNA extracted with guanidinium thyiocyanate, and {alpha}, LHß, and FSHß PTs determined by quantitative RT-PCR. Data from each experiment were expressed as the percentage change versus vehicle-pulsed controls and combined with data from other experiments.

Quantitative RT-PCR

Alpha, LHß, and FSHß PT concentrations were determined by quantitative RT-PCR assay, as previously described [20]. The assay is similar to other quantitative RT-PCR assays developed in our lab to measure mRNA [4, 6] and is based on adding known amounts of a size-altered, competitor RNA to a constant amount of pituitary RNA. Briefly, for each subunit, regions of intron/extron were amplified using specific oligonucleotide primers and a size-altered, competitive template RNA (CT) for each gene. A four-point standard curve was generated by adding a fixed amount of pituitary RNA (100–400 ng/PCR reaction) to an increasing amount of CT (2, 10, 50, and 250 fg). The pituitary and CT RNAs were reverse transcribed, followed by 35 cycles of PCR in the presence of [32P]dCTP. The PCR products were separated by electrophoresis in 3% agarose, the DNA bands excised, and [32P]dCTP incorporation determined by scintillation counting. The PT concentrations were expressed as femtomoles per 100 µg of pituitary RNA. Intraassay coefficients of variation (CVs) were 8.9% ({alpha}), 6.7% (LHß), and 5.0% (FSHß); interassay CVs are 22.2% ({alpha}), 19.2% (LHß), and 14.1% (FSHß). To reduce the effect of interassay variation, all samples from each experiment were run within a single PCR assay.

Radioimmunoassay

To assess secretory responses, LH and FSH were measured in perifusate fractions by RIA using reagents provided by the National Hormone and Pituitary Program. The RIA standards were NIDDK RP-3 (for LH) and RP-2 (for FSH). The assay sensitivities were 0.09 ng/tube for LH and 0.8 ng/tube for FSH. The intra- and interassay CVs were 8.3% and 10.8%, respectively, for the LH assay and 6.3% and 9.6%, respectively, for the FSH assay.

Statistical Analysis

The data were analyzed by one-way analysis of variance, with differences between treatment groups determined by the Duncan multiple-range test.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Figure 1 shows a representative LH and FSH secretory profile in response to pulsatile administration of BK (3 µM) or GnRH (200 pM). The BK pulses stimulated release of both LH and FSH, and the pattern and magnitude of responses to BK were similar to those seen in chambers that received pulsatile GnRH. Also of note, the magnitude of LH responses to BK or GnRH was greater than that seen for FSH.



View larger version (25K):
[in this window]
[in a new window]
  		FIG. 1. LH and FSH release responses to a single pulse of 3 µM BK plus 10 mM KCl or 200 pM GnRH. Arrows indicate the timing of each pulse. Control values (Con; vehicle pulses) are presented in each panel. Mean ± SEM are shown (n = 4–5 per group, derived from two representative experiments)

The transcriptional response to alterations in BK pulse dose (60-min intervals, 6-h duration) is presented in Figure 2. Basal values (vehicle-pulsed controls) for {alpha}, LHß, and FSHß PTs were 57.8 ± 9.0 (mean ± SEM) fmoles per 100 µg of pituitary RNA for {alpha}, 15.8 ± 1.8 for LHß, and 6.9 ± 1.1 for FSHß. Results are presented as the percentage change versus controls in view of varied control values in different experiments. Alpha PT was selectively stimulated by the higher (10 µM) BK pulse dose (50% increase vs. controls, P < 0.05). In contrast, LHß and FSHß PTs were maximally stimulated by 3-µM pulses (79% and 116% increase, respectively, vs. controls; P < 0.05). As presented in Figure 3, BK pulses stimulated both LH and FSH secretion (P < 0.05). Specifically, LH was stimulated 10-fold by the lower, 1-µM BK dose, with maximal (20-fold) increases observed following 3 µM pulses, and FSH was stimulated in a dose-dependant manner, with maximal (2.5-fold) increases seen with the 10-µM pulse dose.



View larger version (18K):
[in this window]
[in a new window]
  		FIG. 2. Gonadotropin subunit primary transcript responses to alterations in BK pulse dose. Experimental groups received 60-min pulses of BK (1, 3, or 10 µM) plus 10 mM KCl for 6 h. Controls (Con) received vehicle pulses. Data are presented as the percentage change versus controls (mean ± SEM, n = 6–10, derived from three or four separate experiments). Degrees of freedom were 3 (between groups) and 32 (within groups); F values were 5.41 ({alpha}), 3.31 (LHß), and 7.07 (FSHß). *P < 0.05 versus control



View larger version (15K):
[in this window]
[in a new window]
  		FIG. 3. LH and FSH release to alterations in BK pulse dose. Perifusate fractions (10 min each) were collected over 60 min before and after the fourth pulse of BK (60-min interval); see Figure 2 for experimental details. For BK pulse groups, peak values per chamber are presented; for vehicle-pulsed controls, mean values from the 10-min perifusate fractions collected over 1 h are shown. Results are expressed as the percentage change versus vehicle-pulsed controls. Mean + SEM are shown; note the different scales for the upper and lower panels. Degrees of freedom were 3 (between groups) and 31 (within groups); F values were 31.93 (LH) and 25.20 (FSH). *P < 0.05 versus control

To examine the effect of calcium pulse frequency on gonadotropin subunit transcription, 3-µM pulses of BK were given every 15, 60, or 180 min for 6 h. As shown in Figure 4, {alpha} PT was selectively stimulated by faster (15 min) pulses of BK (60% increase vs. controls, P < 0.05), and slower frequency pulses were ineffective. The LHß PT was stimulated to a similar degree by 15- and 60-min interval pulses (58–61% increase, P < 0.05), but not by 180-min BK pulses. The FSHß PT was increased by all three BK pulse intervals, but maximal responses (131% increase vs. controls, P < 0.05) were seen with slower pulses (180-min interval). Also, in contrast to the results for {alpha} and LHß, 180-min BK pulses were significantly more effective in stimulating FSHß PT than rapid (15-min) pulses were (P < 0.05). The GnRH pulses given every 60 min stimulated increases in {alpha}, LHß, and FSHß PTs (204%, 60%, and 302% increases, respectively, vs. controls; P < 0.05). Of interest, the magnitude of PT responses to GnRH was significantly greater than that of responses to BK pulses for {alpha} and FSHß but were similar for LHß. The LH secretory responses to pulsatile BK (15- to 22-fold increase vs. controls) were also similar to those seen for GnRH (17-fold increase). In contrast, the FSH secretory response to GnRH (3-fold) was greater than that seen for BK (2-fold, P < 0.05).



View larger version (25K):
[in this window]
[in a new window]
  		FIG. 4. Effect of BK pulse interval (15, 60, or 180 min) on {alpha}, LHß, and FSHß primary transcript levels. Pulse treatments were given for 6 h, and a GnRH pulse group (60-min interval) was included for comparison. Results are expressed as the percentage change versus vehicle-pulsed controls (Con). Mean ± SEM are shown; note the different scale for each panel. The number of chambers per group was 10–12, derived from four or five separate experiments. Degrees of freedom were 4 (between groups) and 50 (within groups); F values were 35.24 ({alpha}), 5.91 (LHß), and 12.66 (FSHß). *P < 0.05 versus control, #P < 0.05 versus 15' pulse BK group; +P < 0.05 versus peak BK treatment group


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The present study is, to our knowledge, the first to show that the frequency of calcium input signals can regulate gonadotropin subunit gene expression at the transcriptional level. These results are in complete accord with our previous findings regarding concentrations of mature message [17], and they suggest that the changes in mRNA expression reflect alterations in the gene transcription rate. The significance of these results is that the response pattern to calcium pulse frequency is similar to that previously reported for GnRH [7]. Alpha and LHß PT were selectively stimulated by faster BK pulses (15- and 60-min intervals). In contrast, FSHß PT was stimulated by all three pulse intervals, with slower (180-min interval) pulses inducing maximal effects. This latter finding is similar to our previous in vivo data, showing that FSHß mRNA is increased by a wider range of GnRH pulse frequencies than that seen for {alpha} and LHß, though slower frequency pulses (120- to 240-min intervals) are optimal [21]. Together, these results strongly suggest that alterations in intracellular calcium play an important role in the transmission of GnRH frequency signals from the plasma membrane to the nucleus. Although we have not compared the pattern (e.g., magnitude, duration, etc.) of intracellular calcium responses to BK versus GnRH, Figure 1 shows that BK stimulates pulsatile LH and FSH secretion with a profile similar to that seen for GnRH. Thus, at the secretory level, the two input signals appear to exert similar effects.

In various pituitary cell types, including the gonadotrope, calcium spikes and oscillations have been correlated to secretory activity [22–24]. In other cell systems, alterations in intracellular calcium can play an important role in regulating gene expression and activating downstream mediators of specific signal transduction pathways. In B lymphocytes, the pattern of increased intracellular calcium can differentially regulate the expression of specific transcription factors (i.e., NFKB, JNK, NFAT) [25]. The frequency of spontaneous calcium spikes regulates neuron differentiation and GABA expression within spinal cord neurons [26]. Other recent studies have revealed that calcium/calmodulin kinase II is regulated by the frequency of calcium oscillations in a cell-free, in vitro model system [27]. The ERK pathway in neuronal-derived CA77 cells is also regulated by the calcium signal pattern, with transient increases in intracellular calcium stimulating and continuous increases suppressing ERK activation, via enhanced MAPK phosphatase I expression [28]. Finally, Villalobos et al. [24] showed that calcium oscillations in lactotrope cells play an important role in the regulation of prolactin gene transcription.

The critical sites in the transmission of GnRH pulse frequency signals within the gonadotrope have yet to be determined. Recently published reports provide evidence for regulation at the GnRH-R level [29] and, in the case of LHß, directly at the promoter region of the gene [30]. Our data suggest that the critical site is postreceptor, because we have shown that the GnRH frequency effect on gonadotropin subunit transcription and mature message expression can be duplicated via bypassing the GnRH-R and pulsing calcium directly. This observation provides evidence for a mechanism whereby activation of a single second-messenger system can regulate two or more genes in a differential manner. However, the downstream mediators of calcium signals remain to be determined. Calcium plays a role in the activation of various intracellular messenger systems, including protein kinase C, protein kinase A, calcium/calmodulin kinase II, and ERK, within the pituitary or gonadotrope-derived cell lines [8, 31–34]. Some data are discordant regarding the roles of some of these intracellular messenger systems in the regulation of gonadotropin subunit gene expression, but this may reflect differences in cell models, treatment paradigms, and end products measured. However, it appears that cross-talk between members of these pathways may be an essential component in the differential subunit gene responses to GnRH.

Of interest, the magnitude of LHß PT and LH secretory responses to pulsatile BK were similar to that seen for pulsatile GnRH (Figs. 4 and 5), supporting a central role for calcium in the regulation of LH expression/secretion, as has been shown by other investigators [13, 15]. In contrast, {alpha} and FSHß PT as well as FSH secretory responses to pulsatile BK were reduced compared to those after GnRH. Recently, we and others have shown that ERK blockade with PD098059 reduces {alpha} and FSHß, but not LHß, mRNA responses to GnRH [10, 13]. These data support the hypothesis that activation of the ERK pathway is essential to produce maximal {alpha} and FSHß responses to GnRH.

In conclusion, pulsatile calcium signals duplicate the {alpha}, LHß, and FSHß transcriptional responses to GnRH pulse frequency, suggesting that transient increases in intracellular calcium play an essential role in the transmission of GnRH signals from the plasma membrane to the gonadotropin subunit genes. Also, these findings indicate that the critical sites modulating GnRH pulse frequency signals are downstream from the gonadotrope plasma membrane.



View larger version (21K):
[in this window]
[in a new window]
  		FIG. 5. LH and FSH secretory responses to pulses of BK (15-, 60-, or 180-min interval) or GnRH; see Figure 4 for experimental details. Control chambers (Con) received 60-min pulses of vehicle. Results are expressed as the percentage change versus control Con (peak values from each BK- or GnRH-pulsed chamber vs. mean values for controls). Mean ± SEM are shown; note the different scales for the upper and lower panels. Degrees of freedom were 4 (between groups) and 52 (within groups); F values were 6.33 (LH) and 91.12 (FSH). *P < 0.05 versus control, #P < 0.05 versus peak BK treatment


   ACKNOWLEDGMENTS
 
The authors would like to thank the University of Virginia Specialized Center for Research in Reproduction (NIH U54-HD28934) for measuring LH and FSH in the Ligand Assay and Analysis Core and the National Hormone and Pituitary Program for providing rat LH and FSH RIA reagents and standard preparations.


   FOOTNOTES
 
First decision: 4 May 2001.

1 Supported by USPHS grants HD-33039 and HD-11489 (to J.C.M.). Back

2 Correspondence: D.J. Haisenleder, University of Virginia Health Sciences Center, 5041 MR-4 Building, Lane Rd., P.O. Box 801387, Charlottesville, VA 22908. FAX: 804 924 1284; djh2q{at}virginia.edu Back

Accepted: July 25, 2001.

Received: April 11, 2001.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Haisenleder DJ, Dalkin AC, Marshall JC. Regulation of gonadotropin gene expression. In: Knobil E, Neill JD (eds.), The Physiology of Reproduction, 2nd ed. New York: Raven Press; 1993: 1793–1813
  2. Shupnik MA. GnRH effects on rat gonadotropin gene transcription in vitro: requirement for pulsatile administration for LH-ß gene stimulation. Mol Endocrinol 1990; 4:1444-1450[Abstract]
  3. Weiss J, Jameson JL, Burrin JM, Crowley WF. Divergent responses of gonadotropin subunit mRNAs to continuous vs. pulsatile GnRH in vitro. Mol Endocrinol 1990; 4:557-561[Abstract]
  4. Kirk SE, Dalkin AC, Yasin M, Haisenleder DJ, Marshall JC. GnRH pulse frequency regulates expression of pituitary follistatin mRNA: a mechanism for differential gonadotrope function. Endocrinology 1994; 135:876-880[Abstract]
  5. Yasin M, Dalkin AC, Haisenleder DJ, Kerrigan JR, Marshall JC. GnRH pulse pattern regulates GnRH receptor gene expression: augmentation by estradiol. Endocrinology 1995; 136:1559-1564[Abstract]
  6. Dalkin AC, Haisenleder DJ, Gilrain JT, Aylor K, Yasin M, Marshall JC. GnRH regulation of gonadotropin subunit gene expression in female rats: actions on FSH beta mRNA involve differential expression of pituitary activin (beta-B) and follistatin mRNAs. Endocrinology 1999; 140:903-908[Abstract/Free Full Text]
  7. Haisenleder DJ, Dalkin AC, Ortolano GA, Marshall JC, Shupnik MA. A pulsatile GnRH stimulus is required to increase transcription of the gonadotropin subunit genes: evidence for differential regulation of transcription by pulse frequency in vivo. Endocrinology 1991; 128::509-517[Abstract]
  8. Stojolkovic SS, Catt KJ. Expression and signal transduction pathways of GnRH receptors. Recent Prog Horm Res 1995; 50:161-205
  9. Garrel G, McArdle CA, Hemmings BA, Counis R. Gonadotropin-releasing hormone and pituitary adenylate cyclase-activating polypeptide affect levels of cyclic adenosine 3',5'-monophosphate-dependent protein kinase A (PKA) subunits in the clonal gonadotrope {alpha}T3-1 cells: evidence for cross-talk between PKA and protein kinase C pathways. Endocrinology 1997; 138:2259-2266[Abstract/Free Full Text]
  10. Haisenleder DJ, Cox ME, Parsons SJ, Marshall JC. Gonadotropin-releasing hormone pulses are required to maintain activation of mitogen-activated protein kinase: role in stimulation of gonadotrope gene expression. Endocrinology 1998; 139:3104-3111[Abstract/Free Full Text]
  11. Levi NL, Hanoch T, Berard O, Roxenblat M, Harris D, Reiss N, Naor Z, Seger R. Stimulation of Jun N-terminal kinase (JNK) by GnRH in pituitary {alpha}T-3 cell line is mediated by PKC, c-Src and CDC42. Mol Endocrinol 1998; 12:815-824[Abstract/Free Full Text]
  12. Roberson MS, Zhang T, Li HL, Mulvaney JM. Activation of the p38 MAPK pathway by GnRH. Endocrinology 1999; 140:1310-1318[Abstract/Free Full Text]
  13. Weck J, Fallest PC, Pitt LK, Shupnik MA. Differential gonadotropin-releasing hormone stimulation of rat luteinizing hormone subunit gene transcription by calcium influx and mitogen-activated protein kinase-signaling pathways. Mol Endocrinol 1998; 12:451-457[Abstract/Free Full Text]
  14. Yokoi T, Ohmichi M, Tasaka K, Kimura A, Kanda Y, Hayakawa J, Tahara M, Hisamoto K, Kurachi H, Murata Y. Activation of the LHß promoter by GnRH requires c-Jun NH2-terminal protein kinase. J Biol Chem 2000; 275:21639-21647[Abstract/Free Full Text]
  15. Naor Z. Signal transduction mechanisms of calcium mobilizing hormones: the case of GnRH. Endocr Rev 1990; 11:326-353[Abstract]
  16. Haisenleder DJ, Yasin M, Marshall JC. The regulation of prolactin, thyrotropin and gonadotropin subunit gene expression by pulsatile or continuous calcium signals. Endocrinology 1993; 133:2055-2061[Abstract]
  17. Haisenleder DJ, Yasin M, Marshall JC. Gonadotropin subunit and GnRH-R gene expression are regulated by alterations in the frequency of calcium pulsatile signals. Endocrinology 1997; 138:5227-5230[Abstract/Free Full Text]
  18. Saunders BD, Sabbagh E, Chin WW, Kaiser UB. Differential use of signal transduction pathways in the GnRH-mediated regulation of gonadotropin subunit gene expression. Endocrinology 1998; 139:1835-1843[Abstract/Free Full Text]
  19. Rush ME, Blake CA. Serum testosterone concentrations during the four-day estrous cycle in normal and adrenalectomized rats. Proc Soc Exp Biol Med 1982; 169:216-221[Medline]
  20. Dalkin AC, Burger LL, Aylor KW, Haisenleder DJ, Workman LJ, Cho S, Marshall JC. Regulation of gonadotropin subunit gene transcription by GnRH: measurement of primary transcript RNAs by quantitative rtPCR assays. Endocrinology 2001; 142:139-146[Abstract/Free Full Text]
  21. Dalkin AC, Haisenleder DJ, Ortolano GA, Ellis TR, Marshall JC. The frequency of GnRH stimulation differentially regulates gonadotropin subunit mRNA expression. Endocrinology 1989; 125:917-924[Abstract]
  22. Holl RW, Thorner MO, Mandell GL, Sullivan JA, Sinha YN, Leong DA. Spontaneous oscillations of intracellular calcium and GH secretion. J Biol Chem 1988; 263:9682-9685[Abstract/Free Full Text]
  23. Tse A, Hille B. GnRH-induced calcium oscillations and rhythmic hyperpolarizations of pituitary gonadotropes. Science 1992; 255:462-464[Abstract/Free Full Text]
  24. Villalobos C, Faught WJ, Frawley LS. Dynamic changes in spontaneous intracellular free calcium oscillations and their relationship to prolactin gene expression in single primary mamotropes. Mol Endocrinol 1998; 12:87-95[Abstract/Free Full Text]
  25. Dolmetsch RE, Lewis RS, Goodnow CC, Healy JI. Differential activation of transcriptional factors induced by calcium response amplitude and duration. Nature 1997; 386:855-858[CrossRef][Medline]
  26. Gu X, Spitzer NC. Distinct aspects of neuronal differentiation encoded by frequency of spontaneous calcium transients. Nature 1995; 375::784-787[CrossRef][Medline]
  27. De Koninck P, Schulman H. Sensitivity of CaM kinase II to the frequency of calcium oscillations. Science 1998; 279:227-230[Abstract/Free Full Text]
  28. Durham PL, Russo AF. Differential regulation of MAPK-responsive genes by duration of a calcium signal. Mol Endocrinol 2000; 14::1570-1582[Abstract/Free Full Text]
  29. Kaiser UB, Sabbagh E, Katzenellenbogen RA, Conn PM, Chin WW. A mechanism for the differential regulation of gonadotropin subunit gene expression by GnRH. Proc Natl Acad Sci U S A 1995; 92::12280-12284[Abstract/Free Full Text]
  30. Weck J, Anderson AC, Jenkins S, Fallest PC, Shupnik MA. Divergent and composite GnRH-responsive elements in the rat LH subunit genes. Mol Endocrinol 2000; 14:472-485[Abstract/Free Full Text]
  31. Schettini G, Cronin MJ, MacLeod , cAMP and calcium-calmodulin interaction in the control of prolactin secretion: evidence for dopamine inhibition of cAMP accumulation and prolactin release after calcium mobilization. Endocrinology 1983; 112:1801-1807[Abstract]
  32. Shraga-Levine Z, Ben-Menahem D, Naor Z. Activation of protein kinase C beta gene expression by GnRH in alpha T3-1 cell line. J Biol Chem 1994; 269:31028-31033[Abstract/Free Full Text]
  33. Cui ZJ, Gorelick FS, Dannies PS. Calcium/calmodulin-dependent protein kinase-II activation in rat pituitary cells in the presence of TRH and dopamine. Endocrinology 1994; 134:2245-2250[Abstract]
  34. Reiss N, Llevi LN, Shacham S, Harris D, Seger R, Naor Z. Mechanism of MAPK activation by GnRH in the pituitary alpha T-3 cell line: differential roles of calcium and PKC. Endocrinology 1997; 138::1673-1682[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Biol. Reprod.Home page
H. A Ferris, H. E Walsh, J. Stevens, P. C Fallest, and M. A Shupnik
Luteinizing Hormone Beta Promoter Stimulation by Adenylyl Cyclase and Cooperation with Gonadotropin-Releasing Hormone 1 in Transgenic Mice and LBetaT2 Cells
Biol Reprod, December 1, 2007; 77(6): 1073 - 1080.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
H. Kanasaki, G. Y. Bedecarrats, K.-Y. Kam, S. Xu, and U. B. Kaiser
Gonadotropin-Releasing Hormone Pulse Frequency-Dependent Activation of Extracellular Signal-Regulated Kinase Pathways in Perifused L{beta}T2 Cells
Endocrinology, December 1, 2005; 146(12): 5503 - 5513.
[Abstract] [Full Text] [PDF]

Home page
 Biol. Reprod.Home page
D.J. Haisenleder, L.L. Burger, K.W. Aylor, A.C. Dalkin, H.E. Walsh, M.A. Shupnik, and J.C. Marshall
Testosterone Stimulates Follicle-Stimulating Hormone {beta} Transcription via Activation of Extracellular Signal-Regulated Kinase: Evidence in Rat Pituitary Cells
Biol Reprod, March 1, 2005; 72(3): 523 - 529.
[Abstract] [Full Text] [PDF]

Home page
 J Mol EndocrinolHome page
L L Burger, D J Haisenleder, A C Dalkin, and J C Marshall
Regulation of gonadotropin subunit gene transcription
J. Mol. Endocrinol., December 1, 2004; 33(3): 559 - 584.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
D. J. Haisenleder, L. L. Burger, K. W. Aylor, A. C. Dalkin, and J. C. Marshall
Gonadotropin-Releasing Hormone Stimulation of Gonadotropin Subunit Transcription: Evidence for the Involvement of Calcium/Calmodulin-Dependent Kinase II (Ca/CAMK II) Activation in Rat Pituitaries
Endocrinology, July 1, 2003; 144(7): 2768 - 2774.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
D. J. Haisenleder, H. A. Ferris, and M. A. Shupnik
The Calcium Component of Gonadotropin-Releasing Hormone-Stimulated Luteinizing Hormone Subunit Gene Transcription Is Mediated by Calcium/Calmodulin-Dependent Protein Kinase Type II
Endocrinology, June 1, 2003; 144(6): 2409 - 2416.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Endocrinol.Home page
T. Yuen, E. Wurmbach, B. J. Ebersole, F. Ruf, R. L. Pfeffer, and S. C. Sealfon
Coupling of GnRH Concentration and the GnRH Receptor-Activated Gene Program
Mol. Endocrinol., June 1, 2002; 16(6): 1145 - 1153.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Haisenleder, D.J.
Right arrow Articles by Marshall, J.C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Haisenleder, D.J.
Right arrow Articles by Marshall, J.C.
Agricola
Right arrow Articles by Haisenleder, D.J.
Right arrow Articles by Marshall, J.C.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS