CaMKII regulates intracellular Ca2+ dynamics in native endothelial cells
| Autor: | Jonathan Ledoux, Chimène Charbel, Fanny Toussaint, Alexandre Blanchette |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
medicine.medical_specialty
education.field_of_study Vascular smooth muscle SERCA Endothelium Physiology Endoplasmic reticulum Population Cell Biology Cell biology chemistry.chemical_compound medicine.anatomical_structure Endocrinology chemistry Internal medicine Ca2+/calmodulin-dependent protein kinase Ionomycin medicine education Molecular Biology Intracellular |
| Zdroj: | Cell Calcium. 58:275-285 |
| ISSN: | 0143-4160 |
| DOI: | 10.1016/j.ceca.2015.06.005 |
| Popis: | Localized endothelial Ca 2+ signalling, such as Ca 2+ pulsars, can modulate the contractile state of the underlying vascular smooth muscle cell through specific endothelial targets. In addition to K Ca 3.1 as a target, Ca 2+ pulsars, an IP 3 R-dependent pulsatile Ca 2+ release from the endoplasmic reticulum (ER) could activate a frequency-sensitive Ca 2+ -dependent kinase such as CaMKII. In the absence of extracellular Ca 2+ , acetylcholine increased endothelial CaMKII phosphorylation and activation, thereby suggesting CaMKII activation independently of Ca 2+ influx. Herein, a reciprocal relation where CaMKII controls endothelial Ca 2+ dynamics has been investigated in mesenteric arteries. Both CaMKIIα and β isoforms have been identified in endothelial cells and close proximity ( 2+ monitoring with high speed confocal microscopy then showed that inhibition of CaMKII with KN-93 significantly increased the population of Ca 2+ pulsars active sites (+89%), suggesting CaMKII as a major regulator of Ca 2+ pulsars in native endothelium. Mechanistic insights were then sought through the elucidation of the impact of CaMKII on ER Ca 2+ store. ER Ca 2+ emptying was accelerated by CaMKII inhibition and ER Ca 2+ content was assessed using ionomycin. Exposure to KN-93 strongly diminished ER Ca 2+ content (−61%) by relieving CaMKII-dependent inhibition of IP 3 receptors (IP 3 R). Moreover, in situ proximity ligation assay suggested CaMKII-IP 3 R promiscuity, essential condition for a protein–protein interaction. Interestingly, segregation of IP 3 R within myoendothelial projection (MEP) appears to be isoform-specific. Hence, only IP 3 R type 1 and type 2 are detected within fenestrations of the internal elastic lamina, sites of MEP, whilst type 3 is absent from these structures. In summary, CaMKII seems to act as a Ca 2+ -sensitive switch of a negative feedback loop regulating endothelial Ca 2+ homeostasis, including Ca 2+ pulsars. |
| Databáze: | OpenAIRE |
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