Differential Expression of Potassium Channels in Placentas from Normal and Pathological Pregnancies: Targeting of the Kir 2.1 Channel to Lipid Rafts

Differential Expression of Potassium Channels in Placentas from Normal and Pathological... Potassium channels play important physiological roles in human syncytiotrophoblasts (hSTBs) from placenta, an epithelium responsible for maternal–fetal exchange. Basal and apical plasma membranes differ in their lipid and protein composition, and the latter contains cholesterol-enriched microdomains. In placental tissue, the specific localization of potassium channels is unknown. Previously, we described two isolated subdomains from the apical membrane (MVM and LMVM) and their respective microdomains (lipid rafts). Here, we report on the distribution of Kir2.1, Kv2.1, TASK-1, and TREK-1 in hSTB membranes and the lipid rafts that segregate them. Immunoblotting experiments showed that these channels are present mainly in the apical membrane from healthy hSTBs. Apical expression versus basal membrane was 84 and 16% for Kir2.1 and Kv2.1, 60 and 30% for TREK-1, and 74 and 26% for TASK-1. Interestingly, Kv2.1 showed differences between apical membrane subdomains: 26 ± 8% was located in the LMVM and 59 ± 9% in MVM. In pathological placentas, the expression distribution changed in the basal membrane: preeclampsia shifted to 50% and intrauterine growth restriction to 42% for TASK-1 and both pathologies increased to 25% for Kir2.1 and Kv2.1, Kir2.1 appeared to be associated with rafts that were sensitive to cholesterol depletion in healthy, but not in pathological, placentas. Kv2.1 and TREK-1 emerged in the nonraft fractions. The precise membrane localization of ion channels in hSTB membranes is necessary to understand the physiological events. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Differential Expression of Potassium Channels in Placentas from Normal and Pathological Pregnancies: Targeting of the Kir 2.1 Channel to Lipid Rafts

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Publisher
Springer-Verlag
Copyright
Copyright © 2012 by Springer Science+Business Media, LLC
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-012-9422-x
Publisher site
See Article on Publisher Site

Abstract

Potassium channels play important physiological roles in human syncytiotrophoblasts (hSTBs) from placenta, an epithelium responsible for maternal–fetal exchange. Basal and apical plasma membranes differ in their lipid and protein composition, and the latter contains cholesterol-enriched microdomains. In placental tissue, the specific localization of potassium channels is unknown. Previously, we described two isolated subdomains from the apical membrane (MVM and LMVM) and their respective microdomains (lipid rafts). Here, we report on the distribution of Kir2.1, Kv2.1, TASK-1, and TREK-1 in hSTB membranes and the lipid rafts that segregate them. Immunoblotting experiments showed that these channels are present mainly in the apical membrane from healthy hSTBs. Apical expression versus basal membrane was 84 and 16% for Kir2.1 and Kv2.1, 60 and 30% for TREK-1, and 74 and 26% for TASK-1. Interestingly, Kv2.1 showed differences between apical membrane subdomains: 26 ± 8% was located in the LMVM and 59 ± 9% in MVM. In pathological placentas, the expression distribution changed in the basal membrane: preeclampsia shifted to 50% and intrauterine growth restriction to 42% for TASK-1 and both pathologies increased to 25% for Kir2.1 and Kv2.1, Kir2.1 appeared to be associated with rafts that were sensitive to cholesterol depletion in healthy, but not in pathological, placentas. Kv2.1 and TREK-1 emerged in the nonraft fractions. The precise membrane localization of ion channels in hSTB membranes is necessary to understand the physiological events.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Mar 4, 2012

References

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