Higher Expression of TRPM7 Channels in Murine Mature B Lymphocytes than Immature Cells.
- Author:
Jin Kyoung KIM
1
;
Jae Hong KO
;
Joo Hyun NAM
;
Ji Eun WOO
;
Kyeong Min MIN
;
Yung E EARM
;
Sung Joon KIM
Author Information
1. Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Seoul 135-710, Korea.
- Publication Type:Original Article
- Keywords:
B lymphocyte;
TRPM7;
Nonselective cation channel;
Cell death;
Bal-17;
WEHI-231
- MeSH:
Antibodies;
B-Lymphocytes*;
Cations, Divalent;
Cell Death;
Dialysis;
Ions;
Ligation;
Lymphocytes;
Permeability;
Precursor Cells, B-Lymphoid;
RNA, Messenger
- From:The Korean Journal of Physiology and Pharmacology
2005;9(2):69-75
- CountryRepublic of Korea
- Language:English
-
Abstract:
TRPM7, a cation channel protein permeable to various metal ions such as Mg2+, is ubiquitously expressed in variety of cells including lymphocytes. The activity of TRPM7 is tightly regulated by intracellular Mg2+, thus named Mg2+-inhibited cation (MIC) current, and its expression is known to be critical for the viability and proliferation of B lymphocytes. In this study, the level of MIC current was compared between immature (WEHI-231) and mature (Bal-17) B lymphocytes. In both cell types, an intracellular dialysis with Mg2+-free solution (140 mM CsCl) induced an outwardly-rectifying MIC current. The peak amplitude of MIC current and the permeability to divalent cation (Mn2+) were several fold higher in Bal-17 than WEHI-231. Also, the level of mRNAs for TRPM7, a molecular correspondence of the MIC channel, was significantly higher in Bal-17 cells. The amplitude of MIC was further increased, and the relation between current and voltage became linear under divalent cation-free conditions, demonstrating typical properties of the TRPM7. The stimulation of B cell receptors (BCR) by ligation with antibodies did not change the amplitude of MIC current. Also, increase of extracellular [Mg2+]c to enhance the Mg2+ influx did not affect the BCR ligation-induced death of WEHI-231 cells. Although the level of TRPM7 was not directly related with the cell death of immature B cells, the remarkable difference of TRPM7 might indicate a fundamental change in the permeability to divalent cations during the development of B cells.
