Michiko Tojo

Eos: a novel member of the Ikaros gene family expressed predominantly in the developing nervous system

We identified a novel member of the Ikaros gene family, which has critical roles in the development of lymphoid lineages. This gene, which we named Eos, was expressed predominantly in the developing central and peripheral nervous system. Eos protein could interact with itself and Ikaros protein through its C‐terminal portion in the yeast two hybrid assay. These findings suggested that Eos may have important roles in neural development similarly to the Ikaros family in the development of hemolymphoid tissue.

Expression of sonic hedgehog signal transducers, patched and smoothened, in human basal cell carcinoma

In basal cell nevus syndrome (BCNS) patients, mutations of a gene, patched (ptc), which encodes a putative signal transducer of sonic hedgehog protein (SHH), were found and are thought to be one of the major causes of BCNS. The SHH signaling pathway is an important developmental pathway, and ptc protein (PTC) is a suppressive component serving as a receptor for the secreted SHH. Another transmembrane protein, smoothened (SMO), forms a complex with PTC and regulates this signaling pathway. Recent transgenic studies have strengthened the importance of the SHH signaling system in the etiology of basal cell carcinoma (BCC). In this study, we examined the expression patterns of mRNA for ptc and smo in two different BCC subtypes and normal skin. We found that the expressions of ptc and smo mRNA were enhanced in the tumor nests of the nodular BCC, especially at the advancing portions, but were under the detectable level in the superficial BCC cases examined, indicating that ptc and smo mRNA expressions might be associated with BCC tumor progression and divide the BCC histologic types into two subtypes, superficial and nodular types. In addition, no obvious signals for ptc and smo mRNA were detected in the normal human epidermis, appendages, or seborrheic keratosis, indicating that the abnormal proliferation of follicular epithelial cells caused by ptc, smo and/or other genetic changes, which also cause ptc and smo overexpressions, might result in BCC tumor formation.

Demonstration of TARC and CCR4 mRNA Expression and Distribution Using In situ RT-PCR in the Lesional Skin of Atopic Dermatitis

Thymus‐ and activation‐regulated chemokine (TARC/CCL17) and its receptor, CC chemokine receptor 4 (CCR4), have been proven to be involved in a number of allergic diseases, especially atopic dermatitis (AD). The purpose of this study was to examine the expression and distribution of TARC and CCR4 mRNAs in samples of AD (n=15, acute lesions 8, chronic lesions 7) and normal skin (n=6). The expression and distribution of TARC and CCR4 mRNAs were detected with the in situ reverse transcription (RT) ‐polymerase chain reaction (PCR) technique. TARC mRNA was expressed in epidermal keratinocytes, dermal endothelial cells and infiltrating cells. CCR4 mRNA was expressed in dermal endothelial cells and infiltrating cells. In acute AD lesional skin, there were more positive cells, and the staining intensity was stronger than in chronic lesions (p<0.05). The distribution of positive cells was as follows: In the epidermis, keratinocytes in the basal layer showed the strongest staining, and keratinocytes in the spinous layer showed moderate staining; the superficial area showed faint staining. In the dermis, infiltrating cells located in the superficial area of the dermis showed the strongest staining, positive staining intensity became weaker and the percentage of positive cells became less as the location became deeper. There were no positive cells in normal skin. These data further substantiate the role of TARC/CCR4 in the pathogenesis of AD.

Expression of the GLI2 oncogene and its isoforms in human basal cell carcinoma

Summary Background Mutations of the patched (Ptc) gene, a developmental regulator implicated in the signalling pathway via sonic hedgehog (Shh) and smoothened (Smo), play an essential pathogenic role in the development of basal cell carcinomas (BCCs). We previously reported the upregulation of Shh signal transducers, including Ptc, Smo and hedgehog‐interacting protein, in BCCs. In vertebrates, specific downstream effectors in the Shh signalling pathway include three zinc‐finger transcription factors, Gli1, Gli2 and Gli3. Gli1 possesses only an activation domain, while Gli2 and Gli3 contain both activation and repression domains. It remains unclear which of these transcription factors are responsible for the development of BCCs.

Expression of a sonic hedgehog signal transducer, hedgehog-interacting protein, by human basal cell carcinoma.

Summary Background  Aberrant activation of the hedgehog pathway has been identified in various human tumours, including familial and sporadic basal cell carcinomas (BCCs). It has been postulated that binding of sonic hedgehog protein (SHH) to its receptor, patched protein (PTC), releases the inhibitory effect of PTC against smoothened protein (SMO), another protein of the SHH signalling pathway. The positive SMO signalling is not downregulated in BCCs because of the mutational inactivation of PTC. Recently, hedgehog‐interacting protein (HIP) was found to bind to SHH directly and attenuate SHH signalling like PTC, while its expression was induced by SHH signals.

Detection of herpes virus genomes in skin lesions from patients with Behçet's disease and other related inflammatory diseases.

Although the aetiology of Behçets disease is still poorly understood, viral infection has long been postulated as one of the factors. To investigate the relationship between herpes viruses and Behçets disease, we used polymerase chain reaction to detect herpes simplex virus 1 (HSV-1) and 2 (HSV-2), and human herpes virus 6 (HHV-6) and 7 (HHV-7) DNA in samples of lesional tissues from patients with Behçets disease and other related inflammatory disorders. Four cases were positive for HSV-1; 1 of 11 Behçets disease cases, 2 of 3 Sweets disease cases and 1 of 3 erythema nodosum cases. Two cases were positive for both HSV-1 and HSV-2; one Behçets disease and one erythema nodosum. All cases were negative for HHV-6 and HHV-7. These findings indicate that there might be some relationship between Behçets disease and the presence of HSV-1 and/or HSV-2 DNA and that HHV-6 and HHV-7 do not seem to be involved in the pathogenesis of Behçets disease. However, HSV-1 and HSV-2 DNAs were also detected in non-Behçets disease lesions, suggesting that HSV-1/2 is not correlated to the direct pathogenesis of Behçets disease.

Different properties of three isoforms (α, β, and γ) of transcription factor AP-2 in the expression of human keratinocyte genes

Abstract. The transcription factor AP-2/promoter system is essential for gene expression associated with ectodermal development, particularly in the neural crest and skin. Three AP-2 isoforms, α, β, and γ, exhibit a highly homologous structure, but their functions are considered to be different. Here, we report on the role of each AP-2 isoform in complex keratinocyte biology including proliferation, differentiation, and carcinogenesis. The expression of AP-2 was investigated immunohistochemically in serial skin sections from normal and psoriatic skin, and squamous cell carcinoma (SCC). AP-2α was present only in the nuclei of normal basal keratinocytes, but was significantly increased in lesional proliferating keratinocytes of both diseases. AP-2β was completely absent from all skin samples except dermal sweat glands, whereas AP-2γ was present homogeneously throughout the epidermis in normal and psoriatic skin as well as in the SCC lesion. Their restricted expression patterns correlated with in vitro DNA binding assays using selective keratinocyte gene promoters and three recombinant AP-2 isoforms generated bacterially as glutathione S-transferase fusion protein. Epidermal growth factor receptor and basal keratin K14 promoters bound to AP-2α and AP-2γ with similar affinities, whereas suprabasal keratin K1, type I transglutaminase, and involucrin promoters predominantly bound to AP-2γ rather than AP-2α. In contrast, AP-2β did not bind to any of the five promoters despite specific binding to the AP-2 consensus probe. These results suggest that AP-2α is closely associated with keratinocyte proliferation and/or carcinogenesis rather than differentiation, while AP-2γ is ubiquitous in all stages of keratinocyte biology. Taken together, three AP-2 isoforms perform unique roles in the spatial and temporal expression of human keratinocyte-related genes, thereby maintaining epidermal homeostasis. Disruption of the epidermal AP-2 balance may contribute to hyperproliferative conditions, such as psoriasis and SCC.

Epidemiology of Behçet’s Disease in Asian Countries and Japan

As Ohno estimated in 1986, patients with Behcet’s disease (BD) are distributed endemically along the ancient Silk Route from Mediterranean countries to Eastern Asian countries. The highest prevalence of the disease is reported for Turks living in Anatolia with 370 patients per 100,000 inhabitants but in northern European and north and south American countries, BD is a rather rare disorder. More than 60% of BD patients are supposed to have HLA-B51 in their genetic background and the world-wide relative risk of HLA-B51 individuals to develop BD is also estimated to be high in the prevalent regions along the “ancient Silk Route”. However, little is known about the prevalence of BD in the middle and northern areas, along the “ancient Silk Route” in China. We would like to report on the recent prevalence and distribution of BD in Asian countries and Japan.

TGF-β1-mediated regulation of thymus and activation-regulated chemokine (TARC/CCL17) synthesis and secretion by HaCaT cells co-stimulated with TNF-α and IFN-γ

Thymus and activation-regulated chemokine (TARC/CCL17) contributes not only to the recruitment of leukocytes, but is also involved in immune disorders, such as atopic dermatitis (AD) and bronchial asthma. We have previously reported that the levels of TARC were high in patients with AD and that lesional epidermis were strongly immunoreactive for TARC. In this paper, the effects of transforming growth factor (TGF)-β1 on the expression of TARC/CCL17 were examined in HaCaT cells, a human keratinocytes (KCs) cell line, co-stimulated with TNF-α and IFN-γ. We found that TGF-β1 down-regulated the TARC synthesis and secretion of HaCaT cells co-stimulated with TNF-α and IFN-γ in a dose-dependent manner. TGF-β1 at a concentration of 10ng/ml maximally inhibited this secretion. Northern blot analysis showed a similar inhibitory effect of TGF-β1 on TARC mRNA expression by HaCaT cells. The TGF-β1-induced down-regulation of TARC/CCL17 in HaCaT cells suggests that TGF-β1 might regulate the TARC-related inflammatory processes, which may be important for understanding the pathogenesis of allergic diseases.

Expression pattern of a novel death-promoting gene, DP5, in the developing murine nervous system

We examined the expression patterns of the DP5 gene, which encodes a protein with apoptosis-inducing activity, in the developing nervous system of mice. This gene was primarily expressed in the spinal motor neurons and peripheral sensory ganglia of mouse embryos and transiently in the postnatal brain, particularly in the entorhinal cortex and hippocampus. These expression patterns suggest that the DP5 gene may be involved in the apoptosis, if not all, of the developing nervous system.