title: Reference genes for quantitative real time PCR in UVB irradiated keratinocytes.
abstract: Real time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) is a sensitive and highly reproducible method often used for determining mRNA levels. To enable proper comparison of gene expression genes expressed at stabile levels within the cells in the studied experimental system need to be identified and used as reference. Ultraviolet B (UVB) radiation is an exogenous carcinogenic stimulus in keratinocytes, and UVB elicited changes have extensively been studied by qRT-PCR, yet a comparison of commonly used reference genes in UVB treatment is lacking. To find the best genes for compensating slight inter-sample variations in keratinocytes in UVB experiments and to understand the potential effects of improper reference gene (RG) selection we have analyzed the mRNA expression of 10 housekeeping genes in neonatal human epidermal keratinocytes (NHEK) after UVB treatment. The biological effect of the used UVB light source was validated by trypane blue exclusion, MTT and comet assays. 20-40mJ/cm(2) dose was chosen for the experiments. The stability of the 10 RGs was assessed by the GeNorm and Normfinder software tools. Regardless of their slightly different algorithm the programs found succinate dehydrogenase complex subunit A (SDHA) to be the best individual RG and SDHA and phosphoglycerate kinase-1 (PGK1) as the most suitable combination. Analysis of the expression of tumor necrosis factor alpha (TNFalpha) and vascular endothelial growth factor (VEGF) found that while the perception of changes in TNF-alpha, a gene undergoing marked upregulation after UVB irradiation is independent of the used RG, changes seen in the more modestly upregulated VEGF are greatly effected by reference gene selection. These findings highlight the importance of reference gene selection in UVB irradiation experiments, and provide evidence that using SDHA or the combination of SDHA and PGK1 as standards could be a reliable method for normalizing qRT-PCR results in keratinocytes after UVB treatment.
authors.affiliation: Department of Dermatology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary Nagyerdei Körut 98, H-4032 Debrecen, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Balogh
authors.forename: György
authors.initials: G
authors.lastname: Paragh
authors.forename: Attila
authors.initials: A
authors.lastname: Juhász
authors.forename: Tamás
authors.initials: T
authors.lastname: Köbling
authors.forename: Dániel
authors.initials: D
authors.lastname: Törocsik
authors.forename: Edit
authors.initials: E
authors.lastname: Mikó
authors.forename: Viktória
authors.initials: V
authors.lastname: Varga
authors.forename: Gabriella
authors.initials: G
authors.lastname: Emri
authors.forename: Irén
authors.initials: I
authors.lastname: Horkay
authors.forename: Beáta
authors.initials: B
authors.lastname: Scholtz
authors.forename: Eva
authors.initials: E
authors.lastname: Remenyik
mesh_terms: D002460:Cell Line; D015870:Gene Expression / Q000528:radiation effects*; D020869:Gene Expression Profiling; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects*; D012333:RNA, Messenger / Q000378:metabolism; D012015:Reference Standards; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000592:standards*; D014466:Ultraviolet Rays
chemical_list: D012333:RNA, Messenger