Facilitation of Ca2+Action Potential Frequency by a Small G Protein Rab3A in Rat Pituitary GH3Cells

Suzuki, Norihiro; Hirono, Moritoshi; Yoshioka, Tohru

doi:10.1006/bbrc.1997.6781

Cited by 4 publications

(1 citation statement)

References 20 publications

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“…TK 137−157 is derived from the noncatalytic domain of p60 v‐src ; it inhibits the tyrosine kinase activity of p60 v‐src and EGF receptor kinase, probably by targeting the catalytic domain which is well conserved amongst tyrosine‐specific protein kinases (48). The mechanism by which these peptides cross the plasma membrane is unknown but the biological efficacy of these peptides on cellular activity has been demonstrated in vivo (49), on tissue fragments/homogenates (28, 50) and in a pituitary cell line [GH 3 ] (51). Tyrosine kinase activity was also blocked with genistein, an isoflavone compound from pseudomonas (52) that specifically inhibits the tyrosine‐specific protein kinase activity of the EGF receptor, pp60 v‐src and pp110gag‐fes, whilst hardly affecting the enzyme activities of serine‐ and threonine‐specific kinases (53).…”

Section: Methodsmentioning

confidence: 99%

Kinase‐Dependent Regulation of the Secretion of Thyrotrophin and Luteinizing Hormone By Glucocorticoids and Annexin 1 Peptides

John¹,

Christian²,

Morris³

et al. 2003

J Neuroendocrinology

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Our previous studies have identified a role for annexin 1 (ANXA1), a protein produced by the pituitary folliculostellate cells, as a paracrine/juxtacrine mediator of the acute regulatory effects of glucocorticoids on the release of adrenocorticotropic hormone and other pituitary hormones. In the present study, we focused on the secretion of thyroid stimulating hormone (TSH) and luteinizing hormone (LH) and used a battery of ANXA1-derived peptides to identify the key domains in the ANXA1 molecule that are critical to the inhibition of peptide release. In addition, as ANXA1 is a substrate for protein kinase C (PKC) and tyrosine kinase, we examined the roles of these kinases in the manifestation of the ANXA1-dependent inhibitory actions of dexamethasone on TSH and LH release. Dexamethasone suppressed the forskolin-induced release of TSH and LH from rat anterior pituitary tissue in vitro. Its effects were mimicked by human recombinant ANXA1 (hrANXA1) and a truncated protein, ANXA1(1-188). ANXA1(Ac2-26), also suppressed stimulated peptide release but it lacked both the potency and the efficacy of the parent protein. Shorter N-terminal ANXA1 sequences were without effect. The PKC inhibitor PKC(19-36) abolished the inhibitory actions of dexamethasone on the forskolin-evoked release of TSH and LH; it also attenuated the inhibitory actions of ANXA1(Ac2-26). Similar effects were produced by annexin 5 (ANXA5) which sequesters PKC in other systems. By contrast, the tyrosine kinase inhibitors, p60v-src (137-157) and genistein, had no effect on the secretion of TSH or LH alone or in the presence of forskolin and/or dexamethasone. Dexamethasone caused the translocation of a tyrosine-phosphorylated species of ANXA1 to the surface of pituitary cells. The total amount of ANXA1 exported from the cells in response to the steroid was unaffected by tyrosine kinase blockade. However, the degree of tyrosine-phosphorylation of the exported protein was markedly reduced by genistein. These results suggest that (i) the ANXA1-dependent inhibitory actions of dexamethasone on the release of TSH and LH require PKC and sequences in the N-terminal domain of ANXA1, but are independent of tyrosine kinase, and (ii) while dexamethasone induces the cellular exportation of a tyrosine-phosphorylated species of ANXA1, tyrosine phosphorylation per se is not critical to the steroid-induced passage of ANXA1 across the membrane.

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Section: Methodsmentioning

confidence: 99%

Kinase‐Dependent Regulation of the Secretion of Thyrotrophin and Luteinizing Hormone By Glucocorticoids and Annexin 1 Peptides

John¹,

Christian²,

Morris³

et al. 2003

J Neuroendocrinology

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miR-709 inhibits GHRP6 induced GH synthesis by targeting PRKCA in pituitary

Cheng

Chen

Song

et al. 2020

Molecular and Cellular Endocrinology

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Hydrogen-Deuterium Exchange Effects on β-Endorphin Release from AtT20 Murine Pituitary Tumor Cells

Ikeda

Suzuki

Kishio

et al. 2004

Biophysical Journal

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Abundant evidences demonstrate that deuterium oxide (D2O) modulates various secretory activities, but specific mechanisms remain unclear. Using AtT20 cells, we examined effects of D2O on physiological processes underlying beta-endorphin release. Immunofluorescent confocal microscopy demonstrated that 90% D2O buffer increased the amount of actin filament in cell somas and decreased it in cell processes, whereas beta-tubulin was not affected. Ca2+ imaging demonstrated that high-K+-induced Ca2+ influx was not affected during D2O treatment, but was completely inhibited upon D2O washout. The H2O/D2O replacement in internal solutions of patch electrodes reduced Ca2+ currents evoked by depolarizing voltage steps, whereas additional extracellular H2O/D2O replacement recovered the currents, suggesting that D2O gradient across plasma membrane is critical for Ca2+ channel kinetics. Radioimmunoassay of high-K+-induced beta-endorphin release demonstrated an increase during D2O treatment and a decrease upon D(2)O washout. These results demonstrate that the H2O-to-D2O-induced increase in beta-endorphin release corresponded with the redistribution of actin, and the D2O-to-H2O-induced decrease in beta-endorphin release corresponded with the inhibition of voltage-sensitive Ca2+ channels. The computer modeling suggests that the differences in the zero-point vibrational energy between protonated and deuterated amino acids produce an asymmetric distribution of these amino acids upon D2O washout and this causes the dysfunction of Ca2+ channels.

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Facilitation of Ca2+Action Potential Frequency by a Small G Protein Rab3A in Rat Pituitary GH3Cells

Cited by 4 publications

References 20 publications

Kinase‐Dependent Regulation of the Secretion of Thyrotrophin and Luteinizing Hormone By Glucocorticoids and Annexin 1 Peptides

Kinase‐Dependent Regulation of the Secretion of Thyrotrophin and Luteinizing Hormone By Glucocorticoids and Annexin 1 Peptides

miR-709 inhibits GHRP6 induced GH synthesis by targeting PRKCA in pituitary

Hydrogen-Deuterium Exchange Effects on β-Endorphin Release from AtT20 Murine Pituitary Tumor Cells

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