Ann Dermatol.  2009 Nov;21(4):376-381. 10.5021/ad.2009.21.4.376.

The Role of Nkx2.5 in Keratinocyte Differentiation

• Hwang C
• Jang S
• Choi DK
• Kim S
• Lee JH
• Lee Y
• Kim CD
• Lee JH

• KMID: 2156500
• DOI: http://doi.org/10.5021/ad.2009.21.4.376

Abstract

BACKGROUND
Nkx2.5 is a homeodomain-containing nuclear transcription protein that has been associated with acute T-lymphoblastic leukemia. In addition, Nkx2.5 has an essential role in cardiomyogenesis. However, the expression of Nkx2.5 in the skin has not been investigated.
OBJECTIVE
In an attempt to screen the differentially regulated genes involved in keratinocyte differentiation, using a cDNA microarray, we identified Nkx2.5 as one of the transcription factors controlling the expression of proteins associated with keratinocyte differentiation.
METHODS
To investigate the expression of Nkx2.5 during keratinocyte differentiation, we used a calcium-induced keratinocyte differentiation model.
RESULTS
RT-PCR and Western blot analysis revealed that the expression of Nkx2.5, in cultured human epidermal keratinocytes, increased with calcium treatment in a time-dependent manner. In normal skin tissue, the expression of Nkx2.5 was detected in the nuclei of the keratinocytes in all layers of the epidermis except the basal layer by immunohistochemistry. In addition, the expression of Nkx2.5 was significantly increased in psoriasis and squamous cell carcinoma, but was barely detected in atopic dermatitis and basal cell carcinoma.
CONCLUSION
These results suggest that Nkx2.5 may play a role in the change from proliferation to differentiation of keratinocytes and in the pathogenesis of skin disease with aberrant keratinocyte differentiation.

Keyword

Keratinocyte differentiation; Nkx2.5; Transcription factor

MeSH Terms

Blotting, Western
Calcium
Carcinoma, Squamous Cell
Dermatitis, Atopic
Epidermis
Humans
Immunohistochemistry
Keratinocytes
Leukemia
Oligonucleotide Array Sequence Analysis
Proteins
Psoriasis
Skin
Skin Diseases
Transcription Factors
Calcium
Proteins
Transcription Factors

Figure

• 

  Fig. 1 mRNA level of Nkx2.5 during calcium-induced keratinocyte differentiation. Two micrograms of total RNA were reverse transcribed with M-MLV reverse transcriptase and used for PCR amplification. Involucrin used as a control marker for differentiation was also increased with calcium treatment.

• 

  Fig. 2 Nkx2.5 expression in calcium-induced keratinocyte differentiation. The protein from cultured keratinocyte extracts of 20 or 30 µg was loaded for SDS-PAGE, and was detected with peptide polyclonal anti-Nkx2.5 antibody, anti-involucrin. Secondary antibodies were obtained from Santa Cruz (Santa Cruz Biotechnology, Santa Cruz, CA, USA). Involucrin used as a control marker for differentiation was also increased with calcium treatment. Actin was used as a loading control.

• 

  Fig. 3 Nkx2.5 expression in several skin diseases. Immunohistochemical staining was performed using Nkx2.5 antibody, at least 3 samples of each disease was studied. The Nkx2.5 expression generally observed in nuclei and/or cytoplasm in various skin tissues. Normal negative means that normal skin was stained in the same procedure only without Nkx2.5 antibody. (A) Normal negative (H&E, ×100), (B) Normal skin (H&E, ×100), (C) Psoriasis (H&E, ×200), (D) AD (H&E, ×200), (E) AK (H&E, ×200), (F) SCC (H&E, ×100), (G) SCC (H&E, ×200), (H) BCC (H&E, ×100), (I) BCC (H&E, ×200). AD: atopic dermatitis, AK: actinic keratosis, SCC: squamous cell carcinoma, BCC: basal cell carcinoma.

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