Gene regulation of alpha4beta2 nicotinic receptors: microarray analysis of nicotine-induced receptor up-regulation and anti-inflammatory effects.
alpha4beta2 Nicotinic acetylcholine receptors play an important role in the reward pathways for nicotine. We investigated whether receptor up-regulation of alpha4beta2 nicotinic acetylcholine receptors involves expression changes for non-receptor genes. In a microarray analysis, 10 muM nicotine altered expression of 41 genes at 0.25, 1, 8 and 24 h in halpha4beta2 SH-EP1 cells. The maximum number of gene changes occurred at 8 h, around the initial increase in (3)[H]-cytisine binding. Quantitative RT-PCR corroborated gene induction of endoplasmic reticulum proteins CRELD2, PDIA6, and HERPUD1, and suppression of the pro-inflammatory cytokines IL-1beta and IL-6. Nicotine suppresses IL-1beta and IL-6 expression at least in part by inhibiting NFkappaB activation. Antagonists dihydro-beta-erythroidine and mecamylamine blocked these nicotine-induced changes showing that receptor activation is required. Antagonists alone or in combination with nicotine suppressed CRELD2 message while increasing alpha4beta2 binding. Additionally, small interfering RNA knockdown of CRELD2 increased basal alpha4beta2 receptor expression, and antagonists decreased CRELD2 expression even in the absence of alpha4beta2 receptors. These data suggest that endoplasmic reticulum proteins such as CRELD2 can regulate alpha4beta2 expression, and may explain antagonist actions in nicotine-induced receptor up-regulation. Further, the unexpected finding that nicotine suppresses inflammatory cytokines suggests that nicotinic alpha4beta2 receptor activation promotes anti-inflammatory effects similar to alpha7 receptor activation.
Hosur
Vishnu
V
Department of Pharmaceutical Science, Northeastern University, Boston, Massachusetts, USA.
Leppanen
Scott
S
Abutaha
Adham
A
Loring
Ralph H
RH
D000470:Alkaloids / Q000378:metabolism; D000704:Analysis of Variance; D001392:Azocines / Q000378:metabolism; D019921:Biotinylation / Q000379:methods; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009447:Neuroblastoma; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D011807:Quinolizines / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection / Q000379:methods; D014316:Tritium / Q000378:metabolism; D000097782:NF-kappaB-Inducing Kinase; D000093843:Quinolizidine Alkaloids
D000470:Alkaloids; D001392:Azocines; D015815:Cell Adhesion Molecules; D016207:Cytokines; D016326:Extracellular Matrix Proteins; D008565:Membrane Proteins; D009538:Nicotine; D018722:Nicotinic Agonists; D019704:Protein Disulfide-Isomerases; D017346:Protein Serine-Threonine Kinases; D011807:Quinolizines; D034741:RNA, Small Interfering; D011978:Receptors, Nicotinic; D014316:Tritium; D000097782:NF-kappaB-Inducing Kinase; C507070:CRELD2 protein, human; C485932:HERPUD1 protein, human; C403531:nicotinic receptor alpha4beta2; C004712:cytisine; D000093843:Quinolizidine Alkaloids; C496931:PDIA6 protein, human