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Interaction of L-selectin, calcium ions, and Rho GTPases in Sertoli cells.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Interaction of L-selectin, calcium ions, and Rho GTPases in Sertoli cells./
Author:	Kao, Tzu-Jen.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2006,
Description:	155 p.
Notes:	Source: Dissertations Abstracts International, Volume: 69-07, Section: B.
Contained By:	Dissertations Abstracts International69-07B.
Subject:	Cellular biology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3245410
ISBN:	9781109840360

Interaction of L-selectin, calcium ions, and Rho GTPases in Sertoli cells.
Kao, Tzu-Jen.

Interaction of L-selectin, calcium ions, and Rho GTPases in Sertoli cells. - Ann Arbor : ProQuest Dissertations & Theses, 2006 - 155 p.

Source: Dissertations Abstracts International, Volume: 69-07, Section: B.

Thesis (Ph.D.)--University of South Carolina, 2006.

This item must not be sold to any third party vendors.

Near the base of mammalian seminiferous epithelium, Sertoli cells are joined by tight junctions, which constitute the blood-testis barrier. Differentiating germ cells are completely enveloped by Sertoli cells and must traverse the tight junctions during the spermatogenic cycle. Following the specific ligand activation of L-selectin, the up-regulated Rho family small G-proteins have been implicated as important modulators of tight junctional dynamics. Although the activation of L-selectin transmits subsequent intracellular signals in a Ca+2-dependent fashion in various cell types, little is understood regarding the signaling pathways utilized by L-selectin in Sertoli cells. Therefore, we have examined the possible resultant calcium influx triggered by specific ligand-activation of cell surface L-selectin receptors or by cross-linking of L-selectin with anti-L-selectin antibodies. Spectrofluorimetric studies demonstrated increase of intracellular Ca +2 levels immediately after the treatment of the L-selectin ligands, fucoidan and sialyl Lewis-a, or after treatment with anti-L-selectin antibody. In addition, the kinetics of Ca+2 influx induced by each L-selectin ligand in ASC-17D cells was investigated using fluorescent real-time imaging. These data demonstrated the increase of intracellular Ca+2 level within two minutes after the treatment of each L-selectin ligand. We then determined the mechanism of Ca+2 influx by investigating L- and T-type voltage-operated Ca+2 channels, which have been suggested to present in the membranes of Sertoli cells. Both spectrofluorimetric and live-cell imaging data demonstrated that Sertoli cells treated with L-type voltage-operated Ca+2 channel antagonists, nifedipine, diltiazem, or verapamil, led to dose-dependent blockage of L-selectin-induced Ca +2 influx. Cells treated with mibedradil, a T-type voltage-operated Ca+2 channel antagonist, resulted in little or no blocking effect. Finally, we determined the changes of Rho and Rac1 expression in ASC-17D cells following the L-selectin-induced Ca+2 influx. Activation assay studies illustrated the up-regulation of Rho and Rac1 following the administration of each L-selectin ligand, and pre-treatment with nifedipine, but not mibefradil, prior to L-selectin ligand-binding, abolished the activation of both Rho and Rac1. Therefore, we conclude that activation of Sertoli cell L-selectin induces Ca+2 influx, which is at least partially regulated by L-type voltage-operated Ca+2 channels, and this L-selectin-induced Ca+2 influx up-regulates Rho and Rac1 proteins.

ISBN: 9781109840360Subjects--Topical Terms:

3172791
Cellular biology.
Subjects--Index Terms:

Calcium

Interaction of L-selectin, calcium ions, and Rho GTPases in Sertoli cells.
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245 1 0 $a Interaction of L-selectin, calcium ions, and Rho GTPases in Sertoli cells.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2006
300 $a 155 p.
500 $a Source: Dissertations Abstracts International, Volume: 69-07, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Millette, Clarke.
502 $a Thesis (Ph.D.)--University of South Carolina, 2006.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Near the base of mammalian seminiferous epithelium, Sertoli cells are joined by tight junctions, which constitute the blood-testis barrier. Differentiating germ cells are completely enveloped by Sertoli cells and must traverse the tight junctions during the spermatogenic cycle. Following the specific ligand activation of L-selectin, the up-regulated Rho family small G-proteins have been implicated as important modulators of tight junctional dynamics. Although the activation of L-selectin transmits subsequent intracellular signals in a Ca+2-dependent fashion in various cell types, little is understood regarding the signaling pathways utilized by L-selectin in Sertoli cells. Therefore, we have examined the possible resultant calcium influx triggered by specific ligand-activation of cell surface L-selectin receptors or by cross-linking of L-selectin with anti-L-selectin antibodies. Spectrofluorimetric studies demonstrated increase of intracellular Ca +2 levels immediately after the treatment of the L-selectin ligands, fucoidan and sialyl Lewis-a, or after treatment with anti-L-selectin antibody. In addition, the kinetics of Ca+2 influx induced by each L-selectin ligand in ASC-17D cells was investigated using fluorescent real-time imaging. These data demonstrated the increase of intracellular Ca+2 level within two minutes after the treatment of each L-selectin ligand. We then determined the mechanism of Ca+2 influx by investigating L- and T-type voltage-operated Ca+2 channels, which have been suggested to present in the membranes of Sertoli cells. Both spectrofluorimetric and live-cell imaging data demonstrated that Sertoli cells treated with L-type voltage-operated Ca+2 channel antagonists, nifedipine, diltiazem, or verapamil, led to dose-dependent blockage of L-selectin-induced Ca +2 influx. Cells treated with mibedradil, a T-type voltage-operated Ca+2 channel antagonist, resulted in little or no blocking effect. Finally, we determined the changes of Rho and Rac1 expression in ASC-17D cells following the L-selectin-induced Ca+2 influx. Activation assay studies illustrated the up-regulation of Rho and Rac1 following the administration of each L-selectin ligand, and pre-treatment with nifedipine, but not mibefradil, prior to L-selectin ligand-binding, abolished the activation of both Rho and Rac1. Therefore, we conclude that activation of Sertoli cell L-selectin induces Ca+2 influx, which is at least partially regulated by L-type voltage-operated Ca+2 channels, and this L-selectin-induced Ca+2 influx up-regulates Rho and Rac1 proteins.
590 $a School code: 0202.
650 4 $a Cellular biology. $3 3172791
653 $a Calcium
653 $a Rho GTPases
653 $a Selectin-L
653 $a Sertoli cells
690 $a 0379
710 2 $a University of South Carolina. $3 1017477
773 0 $t Dissertations Abstracts International $g 69-07B.
790 $a 0202
791 $a Ph.D.
792 $a 2006
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3245410