title: Differential gene expression profiles of two excitable rat cell lines after over-expression of WT- and C121W-β1 sodium channel subunits.
abstract: Voltage-dependent sodium channels are membrane proteins essential for cell excitability. They are composed by a pore-forming α-subunit, encoded in mammals by up to nine different genes, and four different ancillary β-subunits. The expression pattern of the α subunit isoforms confers the distinctive functional and pharmacological properties to different excitable tissues. β-Subunits are important modulators of channel function and expression. Mutation C121W of the β1-subunit causes an autosomal dominant epileptic syndrome without cardiac symptoms. In neuroectoderm GH3 and cardiac H9C2 cells, the over-expression of β1 subunit augments α subunit mRNA and protein levels as well as sodium current density. Interestingly, the introduction of the epileptogenic C121W-β1 subunit produces additional changes in the α-subunit expression pattern of H9C2 cells, leaving unaltered the sodium channel isoform composition of GH3 cells. The challenge of the present work was to identify those genes that were differentially expressed in response to WT- or C121W-β1 subunit over-expression in the two rat cell lines under analysis. Hence, we analyzed the total mRNA extracted from control-untransfected and from WT- and C121W-β1-transfected GH3 and H9C2 cells by DNA-microarray. We found that, in agreement with their different embryonal origin, the over-expression of WT- and C121W-β1 subunits modifies the expression of different gene sets in GH3 and H9C2 cells. Focusing on the effects of the C121W mutation, we found that it causes the modification of 214 genes, most of them were down-regulated (202) in GH3 cells; on the contrary, it determined the up-regulation of only five genes in H9C2 cells. Interestingly, most genes modified by the C121W β1 subunit are involved in pivotal processes of the cell such as cellular communication and protein expression. Our results confirm the important role of the sodium channel β1 subunit in the control of NaCh gene expression, and highlight once more the tissue-specific effect of the C121W mutation.
authors.affiliation: Istituto di Biofisica, CNR, Via De Marini 6, 16149 Genova, Italy. Electronic address: dbaroni@ge.ibf.cnr.it.
authors.forename: D
authors.initials: D
authors.lastname: Baroni
authors.affiliation: Istituto di Biofisica, CNR, Via De Marini 6, 16149 Genova, Italy.
authors.forename: O
authors.initials: O
authors.lastname: Moran
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D003545:Cysteine / Q000235:genetics*; D020869:Gene Expression Profiling; D046228:Microarray Analysis; D009154:Mutation / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014162:Transfection; D014364:Tryptophan / Q000235:genetics*; D062547:Voltage-Gated Sodium Channel beta-1 Subunit / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D062547:Voltage-Gated Sodium Channel beta-1 Subunit; D014364:Tryptophan; D003545:Cysteine
keywords: DNA-microarray; epilepsy; gene expression; mRNA; voltage-gated sodium channel