Targeting of MIST to Src-family kinases via SKAP55–SLAP-130 adaptor complex in mast cells11The rat SKAP55 cDNA nucleotide sequence has been deposited in DDBJ database under accession number AB092812.

AbstractMIST (mast cell immunoreceptor signal transducer; also termed Clnk) is an adaptor protein structurally related to SLP-76-family hematopoietic cell-specific adaptor proteins. We demonstrate here that two major MIST-associated phosphoproteins expressed in mast cell lines are SLAP-130 and SKAP55, adaptors known to interact with the Src-homology (SH) 2 domain of Src-family protein tyrosine kinases (PTKs). MIST directly associated with SLAP-130 via its SH2 domain, and collaboration of SLAP-130 with SKAP55 was required for the recruitment of MIST to Lyn. Furthermore, MIST was preferentially recruited to Fyn rather than Lyn, which is regulated by higher affinity binding of SLAP-130 and SKAP55 with the Fyn-SH2 domain than the Lyn-SH2 domain. Our results suggest that the MIST–SLAP-130–SKAP55 adaptor complex functions downstream of high-affinity IgE receptor-associated Src-PTKs in mast cells

マルチチャネル フォトンカウンティング システム ニヨル キュウチャク ルミネッセンス ノ ケイソク

放射線照射されていない固体において, 表面へのガス吸着に起因する熱ルミネッセンスを生じる現象(吸着ルミネッセンス)について調べた。BaSO_4 : Eu粉末への水, エタノール, アセトン等の蒸気の吸着によるルミネッセンスは, Eu^の励起準位からの緩和発光による615nmの線スペクトルと可視全域に広がる帯スペクトルとから成り, 線スペクトルと帯スペクトルの強度比および帯スペクトルの形状は吸着種に依存して異なる。吸着ルミネッセンスにおよぼす履歴効果と, ルミネッセンススペクトルの温度依存, 雰囲気変化に対する過渡応答等について計測した。The thermoluminescence of unirradiated solids originated from adsorption of gases (adsorption thermoluminescence) has been examined. The luminescence of BaSO_4 : Eu phosphors results from the adsorption of water, ethanol and acetone vapor. The luminescence has a main line spectrum at 615nm and a sub band spectrum ranging from 400 to 700nm. The main line spectrum corresponds to the de-exitation emission of Eu^, whereas the sub band spectrum does not appear in normal thermoluminescence. The ratio of the intensity of the main and sub spectrum and/or the structure of the band spectrum are dependent on adspecies. Sustained emission is observed when the vapor of these organic solvents are introduced into synthesized air. These observations suggest that the measurement of adsoption luminescence spectrum may realize the analysis of environmental gases. The effect of the sample history on adsorption thermoluminescence, the temperature dependence of the luminescence spectrum and the transient response of the luminescence to alterations in the gas environment are measured. It may be concluded that the adsorption thermoluminescence which appeared for samples stored in the atmosphere results from the recombination radiation between electrons trapped into the surface states originated from chemisorbed water and free holes released from the surface states originated from chemisorbed oxygen

Role of Nuclear Claudin-4 in Renal Cell Carcinoma

Claudin-4 (CLDN4) is a tight junction protein to maintain the cancer microenvironment. We recently reported the role of the CLDN4 not forming tight junction in the induction of epithelial-mesenchymal transition (EMT). Herein, we investigated the role of CLDN4 in renal cell carcinoma (RCC), focusing on CLDN4. CLDN4 expression in 202 RCCs was examined by immunostaining. CLDN4 phosphorylation and subcellular localization were examined using high metastatic human RCC SN12L1 and low metastatic SN12C cell lines. In 202 RCC cases, the CLDN4 expression decreased in the cell membrane and had no correlation with clinicopathological factors. However, CLDN4 was localized in the nucleus in 5 cases (2%), all of which were pT3. Contrastingly, only 6 of 198 nuclear CLDN4-negative cases were pT3. CLDN4 was found in the nuclear fraction of a highly metastatic human RCC cell line, SN12L1, but not in the low metastatic SN12C cells. In SN12L1 cells, phosphorylation of tyrosine and serine residues was observed in cytoplasmic CLDN4, but not in membranous CLDN4. In contrast, phosphorylation of serine residues was observed in nuclear CLDN4. In SN12L1 cells, CLDN4 tyrosine phosphorylation by EphA2/Ephrin A1 resulted in the release of CLDN4 from tight junction and cytoplasmic translocation. Furthermore, protein kinase C (PKC)-ε phosphorylated the CLDN4 serine residue, resulting in nuclear import. Contrarily, in SN12C cells that showed decreased expression of EphA2/Ephrin A1 and PKCε, the activation of EphA2/EphrinA1 and PKCε induced cytoplasmic and nuclear translocation of CLDN4, respectively. Furthermore, the nuclear translocation of CLDN4 promoted the nuclear translocation of Yes-associated protein (YAP) bound to CLDN4, which induced the EMT phenotype. These findings suggest that the release of CLDN4 by impaired tight junction might be a mechanism underlying the malignant properties of RCC. These findings suggest that the release of CLDN4 by impaired tight junction might be one of the mechanisms of malignant properties of RCC

Hypomethylation of <i>CLDN4</i> Gene Promoter Is Associated with Malignant Phenotype in Urinary Bladder Cancer

The tight junction (TJ) protein claudin-4 (CLDN4) is overexpressed in bladder urothelial carcinoma (BUC) and correlates with cancer progression. However, the mechanism of CLDN4 upregulation and promotion of malignant phenotype is not clear. Here, we analyzed 157 cases of BUC and investigated the hypomethylation of CpG island in the CLDN4 promoter DNA and its correlation with cancer progression. In hypomethylated cases, CLDN4 expression, cell proliferation, stemness, and epithelial-mesenchymal transition were increased. Treatment of three human BUC cell lines with the demethylating agent aza-2′-deoxycytidine (AZA) led to excessive CLDN4 expression, and, specifically, to an increase in CLDN4 monomer that is not integrated into the TJ. The TJ-unintegrated CLDN4 was found to bind integrin β1 and increase stemness, drug resistance, and metastatic ability of the cells as well as show an anti-apoptosis effect likely via FAK phosphorylation, which reduces upon knockdown of CLDN4. Thus, CLDN4 is overexpressed in BUC by an epigenetic mechanism and the high expression enhances the malignant phenotype of BUC via increased levels of TJ-unintegrated CLDN4. CLDN4 promoter DNA methylation is expected to be a novel indicator of BUC malignant phenotype and a new therapeutic target