The role of nkx2.5 in keratinocyte differentiation.
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.


CONCLUSIONS
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.
Department of Dermatology, College of Medicine, Chungnam National University, Daejeon, Korea.
Chul
C
Hwang
Sunhyae
S
Jang
Dae Kyoung
DK
Choi
Sujong
S
Kim
Joong Hwa
JH
Lee
Young
Y
Lee
Chang Deok
CD
Kim
Jeung Hoon
JH
Lee