PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 15282155

A sea urchin egg jelly peptide induces a cGMP-mediated decrease in sperm intracellular Ca(2+) before its increase.

Takuya Nishigaki·Christopher D Wood·Yoshiro Tatsu·Noboru Yumoto·Toshiaki Furuta·David Elias·Kogiku Shiba·Shoji A Baba·Alberto Darszon
View original source ↗Export metadata ↓

Abstract

Speract, a sperm-activating peptide (SAP) from sea urchin eggs, increases the intracellular concentration of Ca(2+) ([Ca(2+)]i) and modulates sperm motility. We measured the initial sperm response to speract using its caged analog and observed, for the first time, a small but significant decrease in sperm [Ca(2+)]i before the increase. Both directions of the [Ca(2+)]i change were completely blocked in high K(+) seawater. Using membrane-permeant caged cyclic nucleotides (cNMP), only cGMP induced the decrease in [Ca(2+)]i although both cGMP and cAMP increased the [Ca(2+)]i. The decrease in the [Ca(2+)]i induced by cGMP was more notable following a second photolytic event, once [Ca(2+)]i had been elevated by an initial flash. This pattern of [Ca(2+)]i change was confirmed in individual sperm. These results together with pharmacological evidence suggest that the initial [Ca(2+)]i decrease is due to a Na(+)/Ca(2+) exchanger activity, stimulated by hyperpolarization mediated by K(+) efflux through cGMP-regulated K(+) channels.

Explore related subjects

1-Methyl-3-isobutylxanthineAnimalsCalciumCalcium SignalingCell PolarityCyclic AMPCyclic GMPHydrogen-Ion ConcentrationKineticsMaleNucleotides, CyclicOligopeptidesPhotolysisSea UrchinsSodium-Calcium ExchangerSpermatozoaThioureaUltraviolet RaysJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Takuya Nishigaki, Christopher D Wood, Yoshiro Tatsu, Noboru Yumoto, Toshiaki Furuta, David Elias, Kogiku Shiba, Shoji A Baba, Alberto Darszon. 2004-08-15. A sea urchin egg jelly peptide induces a cGMP-mediated decrease in sperm intracellular Ca(2+) before its increase.. https://doi.org/10.1016/j.ydbio.2004.04.035

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2006

Characterization of human islet-like structures generated from pancreatic precursor cells in culture.

This study addresses the characterization of human islet-like structures generated from a newly discovered sparse population of precursor cells (Petropavlovskaia and Rosenberg, 2002) in the human pancreas. These cells may be progenitor cells capable of producing pancreatic cells suitable for the treatment of type 1 diabetes. The cells were cultured successfully in non-adherent stationary cultures and yielded, as an important first step, a 1.9-fold expansion in a serum-free medium developed specifically for this cell type. This expanded population grew as pancreatic cell aggregates, which were analyzed for islet-like characteristics. Specifically, through RT-PCR analyses and functionality assays, we show that cells within the population expressed all four of the endocrine hormone genes and proteins (insulin, glucagon, somatostatin, pancreatic polypeptide). As well, the expanded pancreatic precursor cell population exhibited glucose responsiveness although the produced cells appeared to be still primitive in nature.

1-Methyl-3-isobutylxanthine↗
PubMed2006

Effect of aging on corticosterone secretion in diestrous rats.

The roles of age and prolactin (PRL) in regulating glucocorticoid secretion in diestrous rats were investigated. Adrenal zona fasciculata-reticularis (ZFR) cells from young, adult, middle (mid)-aged, and old female rats were isolated. Estrous cycle stage was determined by light microscopy after vaginal smears. Blood samples were collected from right jugular vein at 0, 30, 60, and 120 min after challenge with adrenocorticotropin (ACTH). During the diestrous phase, plasma levels of estradiol and progesterone were lower in mid-aged and old rats than in either young or adult rats. Age-dependent increases of the basal levels of plasma PRL and corticosterone were observed. No difference of ACTH-increased plasma concentrations of corticosterone was observed among young, adult, mid-aged, and old rats. Aging increased the basal, ACTH-, PRL-, forskolin (an adenylate cyclase activator)-, and 3-isobutyl-l-methylxanthine (IBMX, a non-selective phosphodiesterase inhibitor)-stimulated release of corticosterone and production of adenosine 3', 5'-cyclic monophosphate (cAMP) in ZFR cells. However, the 8-Br-cAMP (a membrane-permeable cAMP)-stimulated release of corticosterone was not affected by age. Taken together, these data indicated that aging increased corticosterone secretion in female rats during diestrous phase, which is in part due to an increase in cAMP accumulation. In conclusion, aging and PRL play a stimulatory role in the co-regulation of corticosterone secretion.

1-Methyl-3-isobutylxanthine↗
PubMed2005

Provasopressin expression by breast cancer cells: implications for growth and novel treatment strategies.

The arginine vasopressin (AVP) gene is expressed in certain cancers such as breast cancer, where it is believed to act as an autocrine growth factor. However, little is known about the regulation of the AVP protein precursor (proAVP) or AVP-mediated signaling in breast cancer and this study was undertaken to address some of the basic issues. The cultured cell lines examined (Mcf7, Skbr3, BT474, ZR75, Mcf10a) and human breast cancer tissue extract were found to express proAVP mRNA. Western analysis revealed multiple forms of proAVP protein were present in cell lysates, corresponding to those detected in human hypothalamus extracts. Monoclonal antibodies directed against different regions of proAVP bound to intact live Mcf7 and Skbr3 cells. Dexamethasone increased the amount of proAVP-associated glycopeptide (VAG) secreted by Skbr3 cells and a combination of dexamethasone, IBMX and 8br-cAMP increased cellular levels of VAG. Exogenous AVP (1, 10, and 100 nM) elevated phospho-ERK1/2 levels, and increased cell proliferation was observed in the presence of 10 nM AVP. Concurrent treatment with the V1a receptor antagonist SR49059 reduced the effects of AVP on proliferation in Mcf7 cells, and abolished it in Skbr3 cells. Results here show that proAVP components are found at the surface of Skbr3 and Mcf7 cells and are also secreted from these cells. In addition, they show that AVP promotes cancer cell growth, apparently through a V1-type receptor-mediated pathway and subsequent ERK1/2 activation. Thus, strategies for targeting proAVP should be examined for their effectiveness in diagnosing and treating breast cancer.

1-Methyl-3-isobutylxanthine↗