title: Three novel sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) 3 isoforms. Expression, regulation, and function of the membranes of the SERCA3 family.
abstract: Sarco/endoplasmic reticulum Ca2+-ATPases (SERCAs) pump Ca2+ into the endoplasmic reticulum. Recently, three human SERCA3 (h3a-c) proteins and a previously unknown rat SERCA3 (r3b/c) mRNA have been described. Here, we (i) document two novel human SERCA3 splice variants h3d and h3e, (ii) provide data for the expression and mechanisms regulating the expression of all known SERCA3 variants (r3a, r3b/c, and h3a-e), and (iii) show functional characteristics of the SERCA3 isoforms. h3d and h3e are issued from the insertion of an additional penultimate exon 22 resulting in different carboxyl termini for these variants. Distinct distribution patterns of the SERCA3 gene products were observed in a series of cell lines of hematopoietic, epithelial, embryonic origin, and several cancerous types, as well as in panels of rat and human tissues. Hypertension and protein kinase C, calcineurin, or retinoic acid receptor signaling pathways were found to differently control rat and human splice variant expression, respectively. Stable overexpression of each variant was performed in human embryonic kidney 293 cells, and the SERCA3 isoforms were fully characterized. All SERCA3 isoforms were found to pump Ca2+ with similar affinities. However, they modulated the cytosolic Ca2+ concentration ([Ca2+]c) and the endoplasmic reticulum Ca2+ content ([Ca2+]er) in different manners. A newly generated polyclonal antibody and a pan-SERCA3 antibody proved the endogenous expression of the three novel SERCA3 proteins, h3d, h3e, and r3b/c. All these data suggest that the SERCA3 gene products have a more widespread role in cellular Ca2+ signaling than previously appreciated.
authors.affiliation: INSERM U348, IFR6 Circulation Lariboisière, Hôpital Lariboisière, 8 Rue Guy Patin, 75475 Paris Cedex 10, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Martin
authors.forename: Raymonde
authors.initials: R
authors.lastname: Bredoux
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Corvazier
authors.forename: Roosje
authors.initials: R
authors.lastname: Van Gorp
authors.forename: Tunde
authors.initials: T
authors.lastname: Kovacs
authors.forename: Pascal
authors.initials: P
authors.lastname: Gelebart
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Enouf
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001792:Blood Platelets / Q000201:enzymology*; D000252:Calcium-Transporting ATPases / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D014644:Genetic Variation; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D014162:Transfection
chemical_list: C506951:Atp2a3 protein, rat; D007527:Isoenzymes; D011994:Recombinant Proteins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506949:ATP2A3 protein, human; D000252:Calcium-Transporting ATPases