Proteome analysis of calcium-induced proteins in human keratinocyte differentiation

In this study we examined the differentially induced protein level by elevating the calcium concentration in the human keratinocyte cell line HaCaT by proteome analysis. HaCaT cell lysates of the cultured chelex-treated medium (0.02 mM Ca2+) and non chelex-treated medium (1.6 mM Ca2+) were studied by two-dimensional polyacrylamide gel electrophoresis with molecular weights ranging between 20 and 120 kDa and isoelectric points of pH 3 similar to 10. The identified proteins with increased expression levels were greater than 2-fold in chelex-treated medium cultured HaCaT cells and isolated protein spots from the polyacrylamide gels of non chelex-treated medium cultured HaCaT cells. Forty protein spots, corresponding to 28 different proteins, were identified peptide mass fingerprinting by matrix-assisted laser desorption/ionization time-of-fight mass spectrometry and the Mascot database searching algorithm. The identified proteins were categorized into several protein groups : intermediate filament, molecular chaperone, energy metabolism, adhesion molecule, binding protein, transcription factor etc.. The proteome analysis and bioinformatics results identify Lamin A/C, KRT5/7/8/14, ZO-1/-2, SOD-1 and peroxiredoxin-1. The proteome analysis suggested that the differentially increased in HaCaT cells cultured under a high calcium condition.