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07:51
Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
Calmodulin effects on steroids-regulated plasma membrane calcium pump activity
Ludmila Zylinska1, Iwona Kowalska, Bozena Ferenc
1Department of Molecular Neurochemistry, Medical University, Lodz, Poland. luska@csk.umed.lodz.pl
Cell Biochemistry and Function
|February 20, 2009
Summary
Steroids rapidly influence cell calcium levels by affecting the plasma membrane calcium pump (PMCA). This action varies by cell type and steroid structure, impacting calcium regulation.
Area of Science:
- Cellular Biology
- Neuroendocrinology
- Biochemistry
Background:
- Non-genomic steroid actions modulate intracellular signaling pathways rapidly.
- Plasma membrane calcium pump (PMCA) precisely regulates intracellular calcium (Ca2+).
- PMCA activity is modulated by calmodulin (CaM) and exhibits isoform diversity.
Purpose of the Study:
- To investigate the role of PMCA isoforms and CaM in Ca2+ uptake regulation by various steroids.
- To examine steroid effects on Ca2+ transport in different cell types.
Main Methods:
- Utilized membranes from rat cortical synaptosomes, PC12 cells, and human erythrocytes.
- Assessed Ca2+ uptake in response to estradiol, DHEA, and pregnenolone (and sulfates) at concentrations from 10(-9) to 10(-6) M.
- Evaluated the impact of calmodulin (CaM) on steroid-mediated Ca2+ transport.
Main Results:
- Steroids generally increased Ca2+ uptake in excitable cell membranes, with variable effects.
- CaM decreased PMCA-mediated Ca2+ transport by 30-40% in most cases.
- Erythrocyte PMCA showed differential regulation, with CaM enhancing Ca2+ extrusion with 17-beta-estradiol and PREG.
Conclusions:
- Steroids can significantly control cytoplasmic calcium concentration within physiological ranges.
- Cell type, PMCA isoform expression, CaM presence, and steroid structure influence the regulatory response.
- Findings highlight the complex interplay between steroids, PMCA, and calcium homeostasis.
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