Single Nucleotide Polymorphism that Accompanies a Missense Mutation (Gln488His) Impedes the Dimerization of Hsp90.

A single nucleotide polymorphism (SNP) that causes a missense mutation of highly conserved Gln488 to His of the alpha isoform of the 90-kDa heat shock protein (Hsp90alpha) molecular chaperone is observed in Caucasians. The mutated Hsp90alpha severely reduced the growth of yeast cells. To investigate this molecular mechanism, we examined the domain-domain interactions of human Hsp90alpha by using bacterial 2-hybrid system. Hsp90alpha was expressed as a full-length form, N-terminal domain (residues 1-400), or middle (residues 401-617) plus C-terminal (residues 618-732) domains (MC domain/amino acids 401-732). The Gln488His substitution in MC domain did not affect the intra-molecular interaction with N-terminal domain, whereas the dimeric interaction-mediated by the inter-molecular interaction between MC domains was decreased to 32%. Gln488Ala caused a similar change, whereas Gln488Thr, which exceptionally occurs in mitochondrial Hsp90 paralog, fully maintained the dimeric interaction. Therefore, the SNP causing Gln488His mutation could abrogate the Hsp90 function due to reduced dimerization

Overexpression of Cortactin Increases Invasion Potential in Oral Squamous Cell Carcinoma.

Cortactin, an F-actin binding protein, stabilizes F-actin networks and promotes actin polymerization by activating the Arp2/3 complex. Overexpression of cortactin has been reported in several human cancers. Cortactin stimulates cell migration, invasion, and experimental metastasis. However, the underlying mechanism is not still understood. In the present study, we therefore evaluated the possibility that cortactin could be appropriate as a molecular target for cancer gene therapy. In 70 primary oral squamous cell carcinomas and 10 normal oral mucosal specimens, cortactin expression was evaluated by immunological analyses, and the correlations of the overexpression of cortactin with clinicopathologic factors were evaluated. Overexpression of cortactin was detected in 32 of 70 oral squamous cell carcinomas; significantly more frequently than in normal oral mucosa. Cortactin overexpression was more frequent in higher grade cancers according to T classification, N classifications, and invasive pattern. Moreover, RNAi-mediated decrease in cortactin expression reduced invasion. Downregulation of cortactin expression increased the expression levels of E-cadherin, beta-catenin, and EpCAM. The siRNA of cortactin also reduced PTHrP expression via EGF signaling. These results consistently indicate that the overexpression of cortactin is strongly associated with an aggressive phenotype of oral squamous cell carcinoma. In conclusion, we propose that cortactin could be a potential molecular target of gene therapy by RNAi targeting in oral squamous cell carcinoma

In-Stent Yellow Plaque at 1 Year After Implantation Is Associated With Future Event of Very Late Stent Failure The DESNOTE Study (Detect the Event of Very late Stent Failure From the Drug-Eluting Stent Not Well Covered by Neointima Determined by Angioscopy)

AbstractObjectivesThis study examined whether coronary angioscopy-verified in-stent yellow plaque at 1 year after drug-eluting stent (DES) implantation is associated with future event of very late stent failure (VLSF).BackgroundAtherosclerosis detected as yellow plaque by angioscopy has been associated with future events of acute coronary syndrome. Development of in-stent neoatherosclerosis is a probable mechanism of VLSF.MethodsThis study included 360 consecutive patients who received successful angioscopic examination at 1 year after implantation of a DES. They were clinically followed up for VLSF defined as cardiac death, acute myocardial infarction or unstable angina, or need for revascularization associated with the stent site.ResultsThe follow-up interval was 1,558 ± 890 days (4.3 ± 2.4 years). The incidence of VLSF was significantly higher in the patients with yellow plaque than in those without (8.1% vs. 1.6%; log rank p = 0.02). Multivariable analysis revealed the presence of yellow plaque (hazard ratio [HR]: 5.38; p = 0.02) and absence of statin therapy (HR: 3.25; p = 0.02) as risks of VLSF.ConclusionsIn-stent atherosclerosis evaluated by yellow plaque at 1 year after the implantation of DES and the absence of statin therapy were risks of VLSF. The underlying mechanism of VLSF appeared to be the progression of atherosclerosis as demonstrated by the yellow plaque

A comprehensive study on the immunological reactivity of the Hsp90 molecular chaperone.

Periodontitis is a chronic infectious disease, Porphyromonas gingivalis being the most implicated pathogen. In the present study, we investigated the role of P. gingivalis HtpG (PgHtpG), a bacterial ortholog of mammalian Hsp90, in the growth of P. gingivalis and also assessed the immunological cross-reactivity of the members of the Hsp90 family. Antiserum against rat liver Hsp90 potently reacted with yeast Hsp90, called Hsc82, and also weakly with human Hsp90 (hHsp90) and human mitochondrial paralog Trap1, but did not react with PgHtpG, Escherichia coli HtpG, or human endoplasmic reticulum paralog Grp94. Moreover, among 19 monoclonal antibodies raised against hHsp90, nine cross-reacted with yeast Hsc82, and one with human Grp94, but none bound to PgHtpG or E. coli HtpG. Among them, three mAbs that strongly reacted with yeast Hsc82 recognized Asn(291)-Ile(304), a conserved region of the family protein. The polyclonal antibody raised against a peptide, Met(315)-Glu(328), of human Grp94, which corresponded to the conserved region of hHsp90, cross-reacted with hHsp90, but not with other Hsp90-family members. Thus, although mammalian Hsp90 shares some immunological reactivity with yeast Hsc82, human Grp94, and human Trap1, it is considerably distinct from its bacterial ortholog, HtpG. Disruption of the P. gingivalis htpG gene neither affected bacterial survival nor altered the sensitivity of P. gingivalis to various forms of stress