Faculty Collaboration Database

Heterogeneity of Kir4.1 channel expression in glia revealed by mouse transgenesis. Glia 2009 Dec;57(16):1706-15

Date

04/22/2009

Pubmed ID

19382212

Pubmed Central ID

PMC2764821

DOI

10.1002/glia.20882

Scopus ID

2-s2.0-71249101105 (requires institutional sign-in at Scopus site)   61 Citations

Abstract

The weakly inwardly rectifying K(+) channel Kir4.1 is found in many glial cells including astrocytes. However, questions remain regarding the relative contribution of Kir4.1 to the resting K(+) conductance of mature astrocytes in situ. We employed a bacterial artificial chromosome transgenic approach in mice to visualize Kir4.1 expression in vivo. These mice (Kir4.1-EGFP) express enhanced green fluorescent protein (EGFP) under the transcriptional control of the Kir4.1 promoter. The brains of adult Kir4.1-EGFP transgenic mice showed co-expression of EGFP and Kir4.1 in astrocytes. In addition, weaker expression of EGFP was detected in NG2+ glial cells when compared with EGFP expression in GFAP+ glial cells. Whole-cell voltage clamp recordings of EGFP+ glial cells in the CA1 area of the adult mouse hippocampus indicated astrocytes displaying properties consistent with both the "passive" and "complex" subpopulations. EGFP+ cells with bright fluorescence had the linear current-voltage (I-V) relationships and extensive gap junctional coupling characteristic of passive astrocytes. However, EGFP+ glia with weaker fluorescence displayed properties associated with complex astrocytes including nonlinear I-V relationships and lack of intercellular gap junctional coupling. Pharmacological blockade of inward currents implied that Kir4.1 channels constitute the dominant resting K(+) conductance in both glial cell types and are more highly expressed in passive astrocytes. These results suggest differential expression of Kir4.1 in glia and that this channel likely underlies the resting K(+) conductance in passive and complex astrocytes.

Author List

Tang X, Taniguchi K, Kofuji P

Author

Kenichiro Taniguchi PhD Associate Professor in the Cell Biology Neurobiology and Anatomy department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Astrocytes
Barium
Blotting, Western
Cerebral Cortex
Cesium
Fluorescent Antibody Technique
Hippocampus
Meclofenamic Acid
Membrane Potentials
Mice
Mice, Transgenic
Microscopy, Confocal
Patch-Clamp Techniques
Potassium Channels, Inwardly Rectifying
Promoter Regions, Genetic