Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

The Sarco(Endo)plasmic Reticulum Ca²⁺-ATPases (SERCA) play a crucial role in Ca²⁺ homeostasis and signaling by mediating re-uptake of Ca²⁺ from the cytosol into intracellular Ca²⁺ stores. Several SERCA isoforms are encoded by three different genes i.e. SERCA 1, SERCA 2 and SERCA 3. In the vascular system, smooth muscle cells express the two spliced variants of the SERCA 2 gene, SERCA 2a and SERCA 2b, SERCA 2b being the most abundant isoform. Arterial endothelial cells express SERCA 3 and also SERCA 2b which is an ubiquitous isoform [1 for review]. Maturation of the rat aorta is associated with an increase in the level of SERCA 2a mRNA, the amounts of SERCA 2b mRNA being identical in young and adult animals [2]. In the adult, SERCA 3 is expressed in a broad variety of tissues [3] but in specific cell types such as endothelial cells, numerous epithelial cells, and purkinje cells in cerebellum [4-7]. SERCA 3 is also present in the hemopoïetic cell lineage and platelets, various lymphoid cell lines and mast cells [8, 9]. In human, two mRNA populations differing by their size in northern-blot were detected, suggesting alternative splicing but the 3’end sequence of the gene did not reveal the existence of an alternative exon [6]. In vascular smooth muscle cells, two major intracellular Ca²⁺ stores have been identified based on differences in the sensitivity of their Ca²⁺ release mechanisms. One is a ryanodine and caffeine-sensitive pool, the other an IP3-sensitive pool and both contain thapsigargin-sensitive Ca²⁺ pumps, SERCA 2a and SERCA 2b [10, 11 for review]. The aim of our work was to study the two SERCA 2 isoforms expression during vascular smooth muscle cell proliferation in culture, and to characterize mouse SERCA 3-spliced variants and their tissue distribution.

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