Simultaneous measurements of exocytosis and intracellular calcium concentration with fluorescent indicators in single pituitary gonadotropes

Masumoto, Nobuyuki; Tasaka, Keiichi; Mizuki, Jirou; Fukami, Kazuyuki; Ikebuchi, Yoshihide; Miyake, Akira

doi:10.1016/0143-4160(95)90067-5

Cited by 20 publications

(12 citation statements)

References 17 publications

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“…Calcium-dependent secretion was confirmed in LNCaP cells using FM1-43 and TMA-DPH imaging assays. These lipophilic dyes have been widely used to measure exocytotic release in neurons, endocrine, or exocrine cells (21,22,34). As noticed from our experiments, FM1-43 fluorescence increased after ionomycin or thapsigargin stimulation in the absence or presence of extracellular calcium, although more efficiently in the latter condition.…”

Section: Discussionsupporting

confidence: 54%

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CaV3.2 T-type Calcium Channels Are Involved in Calcium-dependent Secretion of Neuroendocrine Prostate Cancer Cells

Gackière

Bidaux

Delcourt

et al. 2008

Journal of Biological Chemistry

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Because prostate cancer is, in its early stages, an androgen-dependent pathology, treatments aiming at decreasing testosterone plasma concentration have been developed for many years now. However, a significant proportion of patients suffer a relapse after a few years of hormone therapy. The androgenindependent stage of prostate cancer has been shown to be associated with the development of neuroendocrine differentiation. We previously demonstrated that neuroendocrine prostate cancer cells derived from LNCaP cells overexpress CaV3.2 T-type voltage-dependent calcium channels. We demonstrate here using prostatic acid phosphatase as a marker of prostate secretion and FM1-43 fluorescence imaging of membrane trafficking that neuroendocrine differentiation is associated with an increase in calcium-dependent secretion which critically relies on CaV3.2 T-type calcium channel activity. In addition, we show that these channels are expressed by neuroendocrine cells in prostate cancer tissues obtained from patients after surgery. We propose that CaV3.2 T-type calcium channel up-regulation may account for the alteration of secretion during prostate cancer development and that these channels, by promoting the secretion of potential mitogenic factors, could participate in the progression of the disease toward an androgen-independent stage.Prostate cancer is, in its early stages, an androgen-dependent pathology, meaning that its progression relies on the presence of active steroid male hormones. Treatments developed for many years have been based on this characteristic feature of prostate cancer and, thus, aimed at decreasing the plasma concentration of testosterone or dihydrotestosterone, the prostate active androgen. Although these treatments are particularly valuable in the early development of the disease, leading to the regression of cancers, about a third of the patients suffer a relapse after a few years of hormone therapy. At this stage of hormone refractory disease, deprivation of androgens has no further incidence on the growth of the prostate cancer, and no curative therapy is currently effective (for review, see Ref. 1).The androgen-independent stage of prostate cancer has been shown to be associated with, among others, the development of neuroendocrine differentiation (2). These neuroendocrine features include the appearance of neuroendocrine cell foci surrounded by proliferating epithelial cells (3). Because neuroendocrine prostate cells in normal, hyperplastic, or cancerous tissue secrete many neuropeptides with mitogenic activities like parathyroid hormone-related peptide, calcitonin, or gastrin-related peptides, it has been proposed that paracrine secretion of neurosecretory products released by neuroendocrine cells could be responsible for the progression of cancer toward an androgen-independent stage (for review, see Ref. 4). Indeed, it has been shown for instance that the expression of neuroendocrine markers like chromogranin A is correlated with tumor dedifferentiation (5) and that the presence of neuroendo...

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Section: Discussionsupporting

confidence: 54%

“…Fluorescence was excited at 480 nm and measured at 510 nm. TMA-DPH (1 M) was also used as an indicator of membrane traffic as previously reported (22). Fluorescence protocols were essentially the same as with FM1-43.…”

Section: Methodsmentioning

confidence: 99%

CaV3.2 T-type Calcium Channels Are Involved in Calcium-dependent Secretion of Neuroendocrine Prostate Cancer Cells

Gackière

Bidaux

Delcourt

et al. 2008

Journal of Biological Chemistry

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“…Perifusion of rat anterior pituitary cells with PACAP induces a transient stimulation of gonadotropin release and a concomitant increase in cytosolic calcium concentration Rawlings et al, 1994;Tsujii et al, 1994). The effect of PACAP on gonadotropin, nitric-oxide synthase I, and estrogen receptor expression involves the cAMP/PKA pathway (Ishizaka et al, 1993;Winters et al, 1997;Schreihofer et al, 2001;Garrel et al, 2002), whereas its acute action on FSH/LH release is under the control of calcium elevation Masumoto et al, 1995). Besides its direct action on gonadotropin release, PACAP has also been shown to increase rat GnRH re-PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE ceptor gene promoter activity through the cAMP/PKA pathway (Cheng and Leung, 2001;Ngan et al, 2001;Pincas et al, 2001;Sadie et al, 2003).…”

Section: B Effects Of Pituitary Adenylate Cyclase-activating Polypepmentioning

confidence: 99%

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

et al. 2009

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“…For measurement of exocytosis, the gonadotrophs were incubated with a final concentration of 1 µM TMA-DPH and the 430 nm fluorescence of single cells at 360 nm excitation was measured (Masumoto et al 1993(Masumoto et al , 1995. Cells were intermittently irradiated for 10-50 ms every 1 s to prevent damage caused by ultraviolet rays.…”

Section: Measurement Of [Ca 2+ ] I and Exocytosis In Gonadotrophsmentioning

confidence: 99%

Rab3B is essential for GnRH-induced gonadotrophin release from anterior pituitary cells

Tasaka

Masumoto²,

Mizuki³

et al. 1998

Journal of Endocrinology

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Gonadotrophin-releasing hormone (GnRH) induces the release of gonadotrophins via an increase in cytosolic Ca 2+ concentration ([Ca 2+ ]). Rab3B, a member of the small GTP-binding protein Rab family, is known to be involved in Ca 2+ -regulated exocytosis in pituitary cells. However, it is not known whether Rab3B functions in the physiological process regulated by GnRH in gonadotrophs. In this study using antisense oligonucleotide against Rab3B (AS-Rab3B) we determined that Rab3B is involved in GnRH-induced gonadotrophin release. Rab3B immunopositive cells were reduced in 24% of pituitary cells by AS-Rab3B. This treatment did not affect the population of gonadotrophs or the intracellular contents of gonadotrophins. However, AS-Rab3B significantly inhibited the total amount of basal and GnRH-induced gonadotrophin released from pituitary cells. These results show that Rab3B is involved in basal and GnRH-induced gonadotrophins release but not the storage of gonadotrophins. Next, the changes in [Ca 2+ ] and exocytosis in gonadotrophs treated with AS-Rab3B were compared among Rab3B-positive and -negative cells. The change in [Ca 2+ ] was not different in the two groups, but exocytosis was significantly inhibited in Rab3B-negative cells. These results suggest that Rab3B is essential for GnRH-regulated exocytosis downstream of cytosolic Ca 2+ in gonadotrophs.

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Simultaneous measurements of exocytosis and intracellular calcium concentration with fluorescent indicators in single pituitary gonadotropes

Cited by 20 publications

References 17 publications

CaV3.2 T-type Calcium Channels Are Involved in Calcium-dependent Secretion of Neuroendocrine Prostate Cancer Cells

CaV3.2 T-type Calcium Channels Are Involved in Calcium-dependent Secretion of Neuroendocrine Prostate Cancer Cells

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

Rab3B is essential for GnRH-induced gonadotrophin release from anterior pituitary cells

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