title: Functional properties of a new voltage-dependent calcium channel alpha(2)delta auxiliary subunit gene (CACNA2D2).
abstract: We have positionally cloned and characterized a new calcium channel auxiliary subunit, alpha(2)delta-2 (CACNA2D2), which shares 56% amino acid identity with the known alpha(2)delta-1 subunit. The gene maps to the critical human tumor suppressor gene region in chromosome 3p21.3, showing very frequent allele loss and occasional homozygous deletions in lung, breast, and other cancers. The tissue distribution of alpha(2)delta-2 expression is different from alpha(2)delta-1, and alpha(2)delta-2 mRNA is most abundantly expressed in lung and testis and well expressed in brain, heart, and pancreas. In contrast, alpha(2)delta-1 is expressed predominantly in brain, heart, and skeletal muscle. When co-expressed (via cRNA injections) with alpha(1B) and beta(3) subunits in Xenopus oocytes, alpha(2)delta-2 increased peak size of the N-type Ca(2+) currents 9-fold, and when co-expressed with alpha(1C) or alpha(1G) subunits in Xenopus oocytes increased peak size of L-type channels 2-fold and T-type channels 1.8-fold, respectively. Anti-peptide antibodies detect the expression of a 129-kDa alpha(2)delta-2 polypeptide in some but not all lung tumor cells. We conclude that the alpha(2)delta-2 gene encodes a functional auxiliary subunit of voltage-gated Ca(2+) channels. Because of its chromosomal location and expression patterns, CACNA2D2 needs to be explored as a potential tumor suppressor gene linking Ca(2+) signaling and lung, breast, and other cancer pathogenesis. The homologous location on mouse chromosome 9 is also the site of the mouse neurologic mutant ducky (du), and thus, CACNA2D2 is also a candidate gene for this inherited idiopathic generalized epilepsy syndrome.
authors.affiliation: Hamon Center for Therapeutic Oncology Research, Departments of Internal Medicine, Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390, USA.
authors.forename: B
authors.initials: B
authors.lastname: Gao
authors.forename: Y
authors.initials: Y
authors.lastname: Sekido
authors.forename: A
authors.initials: A
authors.lastname: Maximov
authors.forename: M
authors.initials: M
authors.lastname: Saad
authors.forename: E
authors.initials: E
authors.lastname: Forgacs
authors.forename: F
authors.initials: F
authors.lastname: Latif
authors.forename: M H
authors.initials: MH
authors.lastname: Wei
authors.forename: M
authors.initials: M
authors.lastname: Lerman
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: E
authors.initials: E
authors.lastname: Perez-Reyes
authors.forename: I
authors.initials: I
authors.lastname: Bezprozvanny
authors.forename: J D
authors.initials: JD
authors.lastname: Minna
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015220:Calcium Channels / Q000235:genetics*; D002874:Chromosome Mapping; D002893:Chromosomes, Human, Pair 3; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis
chemical_list: D015220:Calcium Channels; D018076:DNA, Complementary