Isoform diversity of the inositol trisphosphate receptor in cell types of mouse origin.
Previous reports suggested the expression of four or five different Ins(1,4,5)P3 receptor [Ins(1,4,5)P3R] isoforms in mouse cells [Ross, Danoff, Schell, Snyder and Ullrich (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 4265-4269; De Smedt, Missiaen, Parys, Bootman, Mertens, Van Den Bosch and Casteels (1994) J. Biol. Chem. 269, 21691-21698]. To explore this diversity further, we have isolated and sequenced partial clones of two Ins(1,4,5)P3R mRNAs from the mouse embryonic C3H10T1/2 cell line. These clones showed between 94.2 and 94.9% sequence identity with the corresponding rat Ins(1,4,5)P3R-II and Ins(1,4,5)P3R-III isoforms. Based on these newly obtained sequences we have determined the relative expression of the different Ins(1,4,5)P3R mRNAs in cultured cells and in animal tissues of mouse origin by a ratio reverse transcriptase polymerase chain reaction (RT-PCR). Ins(1,4,5)P3R-I was very prominent in brain and cerebellum and Ins(1,4,5)P3R-II in epithelia such as kidney as well as in both cardiac and skeletal muscle. Ins(1,4,5)P3R-III was highly expressed in all cultured cell types and in tissues with high cell turnover, e.g. testis. The prominent expression of Ins(1,4,5)P3R-I and Ins(1,4,5)P3R-III in A7r5 and C3H10T1/2 cells respectively was confirmed by immunoblot analysis and was compatible with a lower threshold for Ins(1,4,5)P3-induced Ca2+ release in the former cell type. Screening of a large number of mouse cell lines and tissues revealed the presence of Ins(1,4,5)P3R-I as well as of the Ins(1,4,5)P3R-II and Ins(1,4,5)P3R-III isoforms which were identified in the present study, but in contrast with previous reports there was no evidence for more isoform diversity.
De Smedt
H
H
Laboratory of Physiology, Campus Gasthuisberg O/N, K.U. Leuven, Belgium.
Missiaen
L
L
Parys
J B
JB
Henning
R H
RH
Sienaert
I
I
Vanlingen
S
S
Gijsens
A
A
Himpens
B
B
Casteels
R
R
D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000145:classification / Q000235:genetics*; D002460:Cell Line; D002531:Cerebellum / Q000737:chemistry; D003001:Cloning, Molecular; D017931:DNA Primers; D004622:Embryo, Mammalian / Q000166:cytology; D014644:Genetic Variation; D015544:Inositol 1,4,5-Trisphosphate; D053496:Inositol 1,4,5-Trisphosphate Receptors; D051379:Mice; D008861:Microsomes / Q000737:chemistry; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012194:RNA-Directed DNA Polymerase; D018160:Receptors, Cytoplasmic and Nuclear / Q000145:classification / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014018:Tissue Distribution
D015220:Calcium Channels; D017931:DNA Primers; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; D012194:RNA-Directed DNA Polymerase; D002118:Calcium