Ann Dermatol.  2012 Aug;24(3):261-266. 10.5021/ad.2012.24.3.261.

Epigenetic Modulation of Gene Expression during Keratinocyte Differentiation

• Back SJ
• Im M
• Sohn KC
• Choi DK
• Shi G
• Jeong NJ
• Lee Y
• Seo YJ
• Kim CD
• Lee JH

• KMID: 2265297
• DOI: http://doi.org/10.5021/ad.2012.24.3.261

Abstract

BACKGROUND
Epigenetic modulation of gene expression occurs by various methods, including DNA methylation and histone modification. DNA methylation of specific genes may affect the chromatin structure, preventing access by the transcriptional machinery. Although gene expression is dramatically changed during keratinocyte differentiation, there is no evidence of epigenetic modulation during the process of epidermal stratification.
OBJECTIVE
We investigated whether epigenetic modulation is involved in keratinocyte differentiation-specific gene regulation.
METHODS
We used trypsin to produce epidermal fragmentation (named T1-T4) and performed a morphological analysis using hematoxylin-eosin stain and cytokeratin expression based on reverse transcription polymerase chain reaction. We then constructed a DNA methylation microarray.
RESULTS
Each epidermal fragment showed morphological features of the epithelial layer. T1 represented the basal layer, T2 was the spinous layer, T3 was the granular layer, and T4 was the cornified layer. The level of the K14 proliferation marker was increased in the T1 fraction, and the level of K10 differentiation marker was increased in the T2-T4 fractions. Using a methylation microarray with the T1 and T4 fractions, we obtained many hypermethylated and hypomethylated genes from differentiated keratinocytes.
CONCLUSION
The importance of epigenetic modulation in target gene expression during keratinocyte differentiation is identified.

Keyword

Cell differentiation; DNA methylation; Epigenomics; Keratinocytes

MeSH Terms

Cell Differentiation
Chromatin
DNA Methylation
Epigenomics
Gene Expression
Histones
Keratinocytes
Keratins
Methylation
Polymerase Chain Reaction
Reverse Transcription
Trypsin
Chromatin
Histones
Keratins
Trypsin

Figure

• 

  Fig. 1 Histologic analysis of an epidermal sample. (A) A H&E stained section of the entire epidermis after thermolysin incubation and removal of the dermis. Epidermal fragments remaining after the first, second, and third trypsin treatments, respectively, constitute the T1 (B), T2 (C), and T3 fractions (D). Fragments shown in (E) are mainly composed of the cornified layer and constitute the T4 fraction.

• 

  Fig. 2 Reverse transcription polymerase chain reaction analysis for K14 and K10 in an epidermal sample. The level of the epidermal differentiation marker keratin 10 (K10) is increased, while the level of the proliferation marker keratin 14 (K14) is decreased in the fractionated epidermal cells, indicating sample preparation was successfully performed.

• 

  Fig. 3 Scatter plot of the methylation microarray. Genomic DNA was isolated from the T1 and T4 fractions, labeled with Cy3 and Cy5, then applied to the methylation microarray chip. After hybridization, the microarray slide was scanned and analyzed. Each gene was spotted according to its signal intensity.

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