Kazuhiko Kogawa

Expression of AIRE gene in peripheral monocyte/dendritic cell lineage

The responsible gene for autoimmune polyglandular syndrome type 1, known as autoimmune regulator (AIRE), was identified by positional cloning. The AIRE gene was reported to be expressed in the thymus medulla and lymph nodes. However, an expression of the AIRE gene in peripheral blood cells has not yet been reported. In the present study, we found that the AIRE gene was restrictively expressed in peripheral CD14-positive monocytes but not in CD4-positive T cells nor polymorphonuclear cells, as assessed by RT-PCR. Moreover, immunocytochemical study revealed the expression of the AIRE protein not only in CD14-positive monocytes but also in differentiated dendritic cells, cultured in RPMI1640 medium containing 800 U/ml GM-CSF, 1000 U/ml IL-4 and 100 U/ml TNF-alpha. Thus, it was concluded that the AIRE gene is restrictively expressed in the peripheral monocyte/dendritic cell lineage.

In vivo cooperation between Bcl-xL and the phosphoinositide 3-kinase-Akt signaling pathway for the protection of epidermal keratinocytes from apoptosis

To investigate the function of Bcl‐xL in the skin, we established keratinocyte‐specific Bcl‐x gene‐targeted mice under the keratin 5 promoter (K5). K5.Bcl‐xL– / – mice were viable, devoid of alteration in the development of skin or appendages. However, they harbored spontaneous apoptotic keratinocytes in the epidermis. Bcl‐xL‐deficient keratinocytes cultured in vitro readily underwent apoptosis in the absence of growth factors, but the addition of HGF or EGF resulted in restoration of cell survival, which was reversed by treatment with wortmannin, an inhibitor of phosphoinositide‐3 kinase (PI3K). Topical treatment of K5.Bcl‐xL− / − mice with wortmannin sensitized the skin for apoptosis induced by UV (UV) B, although wild‐type epidermis was only marginally affected by this treatment, suggesting that the resistance to UVB largely depended on PI3K‐Akt signaling in Bcl‐xL‐deficient mice but not in wild‐type mice. Furthermore, UVB irradiation resulted in redistribution of phosphorylated Akt from the basal layer to the suprabasal layer, indicating that Akt could spatially cooperate with Bcl‐xL upon UVB exposure in the upper epidermis where Bcl‐xL is normally localized. These results suggest that Bcl‐xL and the PI3K‐Akt pathway form a cooperative, intercompensatory axis for the protection of epidermal keratinocytes from apoptosis in vivo.

Establishment of an embryonic stem (ES) cell line derived from a non-obese diabetic (NOD) mouse: in vivo differentiation into lymphocytes and potential for germ line transmission

A non‐obese diabetic (NOD) mouse‐derived embryonic stem (ES) cell line has been stably maintained in an undifferentiated state with a characteristic ES cell‐like morphology, expressing the stem cell marker alkaline phosphatase, and displaying a normal diploid karyotype. After injecting the NOD‐ES cells into blastocysts, chimeric mice were obtained. Small but significant numbers of lymphocytes expressed the NOD‐derived MHC allele. When a chimeric mouse was mated with C57BL/6 mice, an agouti mouse was obtained, having the NOD‐derived H‐2 I‐Aβ g7 haplotype. Thus, an NOD‐ES cell line which can differentiate into lymphocytes with potential for germ line transmission was successfully established.

Autoimmune Regulator (AIRE) Gene Is Expressed in Human Activated CD4 T-Cells and Regulated by Mitogen-Activated Protein Kinase Pathway

The autoimmune regulator (AIRE) gene is a gene responsible for autoimmune polyendocrinopathy‐candidiasis‐ectodermal dystrophy. Here we show that AIRE is expressed in human peripheral CD4‐positive T‐cells, and most highly in antigen‐ and interleukin 2‐stimulated T (IL‐2T) cells. Mitogen‐activated protein kinases (MAPKs), including MAPK kinase (MEK) 1/2 and p38 MAPK, were phosphorylated in IL‐2T cells and the expression of the AIRE gene was inhibited by a specific p38 MAPK inhibitor (SB203580), thereby indicating that AIRE gene expression is controlled by the MAPK pathway in IL‐2T cells. These data suggested the possible significance of the AIRE gene in the peripheral immune system.

TYK2 Promoter Variant and Diabetes Mellitus in the Japanese

Background Recently, natural mutation of Tyrosine kinase 2 (Tyk2) gene has been shown to determine susceptibility to murine virus-induced diabetes. In addition, a previous human genome-wide study suggested the type 1 diabetes (T1D) susceptibility region to be 19p13, where the human TYK2 gene is located (19p13.2). Methods Polymorphisms of TYK2 gene at the promoter region and exons were studied among 331 healthy controls, and 302 patients with T1D and 314 with type 2 diabetes (T2D) in the Japanese. Findings A TYK2 promoter haplotype with multiple genetic polymorphisms, which are in complete linkage disequilibrium, named TYK2 promoter variant, presenting decreased promoter activity, is associated with an increased risk of not only T1D (odds ratio (OR), 2.4; 95% confidence interval (CI), 1.2 to 4.6; P = 0.01), but also T2D (OR, 2.1; 95% CI, 1.1 to 4.1; P = 0.03). The risk is high in patients with T1D associated with flu-like syndrome at diabetes onset and also those without anti-glutamic acid decarboxylase autoantibody. Interpretation The TYK2 promoter variant is associated with an overall risk for diabetes, serving a good candidate as a virus-induced diabetes susceptibility gene in humans. Funding Ministry of Education, Culture, Sports, Science and Technology and of Health, Labor and Welfare of Japan.