Properties of the electrogenic activity of bacteriorhodopsin

In this study, we analyzed the photoelectric current generated by bacteriorhodopsin adsorbed on a polymer film, “Lumirror” (Muneyuki et al. in FEBS Lett 427:109–114, 1998). We could examine the photoelectric current over a wide range of light intensity and pH values using the same membrane owing to the mechanical and chemical stability of the thin polymer film. We analyzed the photoelectric current by comparison with a simple equivalent electric circuit. Analysis of experimental results obtained at different light intensities suggested that the electromotive force of the bacteriorhodopsin was independent of light intensity. The pH dependence of the photoelectric current suggested that the bacteriorhodopsin could generate a maximum electromotive force at approximately pH 6.     

ATM Mediates pRB Function To Control DNMT1 Protein Stability and DNA Methylation

The retinoblastoma tumor suppressor gene (RB) product has been implicated in epigenetic control of gene expression owing to its ability to physically bind to many chromatin modifiers. However, the biological and clinical significance of this activity was not well elucidated. To address this, we performed genetic and epigenetic analyses in an Rb-deficient mouse thyroid C cell tumor model. Here we report that the genetic interaction of Rb and ATM regulates DNMT1 protein stability and hence controls the DNA methylation status in the promoters of at least the Ink4a, Shc2, FoxO6, and Noggin genes. Furthermore, we demonstrate that inactivation of pRB promotes Tip60 (acetyltransferase)-dependent ATM activation; allows activated ATM to physically bind to DNMT1, forming a complex with Tip60 and UHRF1 (E3 ligase); and consequently accelerates DNMT1 ubiquitination driven by Tip60-dependent acetylation. Our results indicate that inactivation of the pRB pathway in coordination with aberration in the DNA damage response deregulates DNMT1 stability, leading to an abnormal DNA methylation pattern and malignant progression.     

Phosphopeptides designed for 5-methylcytosine recognition

An artificial phosphopeptide has been developed through rational design of the interaction with 5-methylcytosine in duplex DNA. The peptide consists of two tandem zinc finger motifs, in one of which the glutamate was replaced with a phosphotyrosine, the phosphotyrosine in the peptide being effective for methylcytosine selectivity of DNA binding. The flexible modulation of the target methylated sequence by rearrangement of zinc finger peptides is possible, and the phosphopeptide provided us an important hint for expansion of the codes for the interactions of zinc fingers with DNA to methylated DNA sequences. The fluorescence-labeled phosphopeptide provided information on the methylation status of genomic DNA through fluorescence anisotropy after a 10 min incubation.     

Yellow fever virus NS2B/NS3 protease: hydrolytic properties and substrate specificity

MCPH is a neurodevelopmental disorder characterized by a global reduction in cerebral cortical volume. Homozygous mutation of the MCPH5 gene, also known as ASPM, is the most common cause of the MCPH phenotype. To elucidate the roles of ASPM during embryonic development, the zebrafish aspm was identified, which is specifically expressed in proliferating cells in the CNS. Morpholino-mediated knock-down of aspm resulted in a significant reduction in head size. Furthermore, aspm-deficient embryos exhibited a mitotic arrest during early development. These findings suggest that the reduction in brain size in MCPH might be caused by lack of aspm function in the mitotic cell cycle and demonstrate that the zebrafish can provide a model system for congenital diseases of the human nervous system.     

Protective effects of cilengitide on inflammation in chondrocytes under excessive mechanical stress

Chondrocytes constantly receive external stimuli, which regulates remodeling. An optimal level of mechanical stress is essential for maintaining chondrocyte homeostasis, however, excessive mechanical stress induces inflammatory cytokines and protease, such as matrix metalloproteinases (MMPs). Therefore, excessive mechanical stress is considered to be one of the main causes to cartilage destruction leading to osteoarthritis (OA). Integrins are well‐known as cell adhesion molecules and act as receptors for extracellular matrix (ECM), and are believed to control intracellular signaling pathways both physically and chemically as a mechanoreceptor. However, few studies have focused on the roles and functions of integrins in inflammation caused by excessive mechanical stress. In this study, we examined the relationship between integrins (αVβ3 and αVβ5) and the expression of inflammatory factors under mechanical loading in chondrocytes by using an integrin receptor antagonist (cilengitide). Cilengitide suppressed the gene expression of interleukin‐1β (IL‐1β), tumor necrosis factor‐α (TNF‐α), matrix metalloproteinase‐3 (MMP‐3), and MMP‐13 induced by excessive mechanical stress. In addition, the protein expression of IL1‐β and MMP‐13 was also inhibited by the addition of cilengitide. Next, we investigated the involvement of intracellular signaling pathways in stress‐induced integrin signaling in chondrocytes by using western blotting. The levels of p‐FAK, p‐ERK, p‐JNK, and p‐p38 were enhanced by excessive mechanical stress and the enhancement was suppressed by treatment with cilengitide. In conclusion, this study revealed that excessive mechanical stress may activate integrins αVβ3 and αVβ5 on the surface of chondrocytes and thereby induce an inflammatory reaction by upregulating the expression of IL‐1β, TNF‐α, MMP‐3, and MMP‐13 through phosphorylation of FAK and MAPKs.     

Glucocorticoid‐transactivated TSC22D3 attenuates hypoxia‐ and diabetes‐induced Müller glial galectin‐1 expression via HIF‐1α destabilization

Galectin‐1/LGALS1, a newly recognized angiogenic factor, contributes to the pathogenesis of diabetic retinopathy (DR). Recently, we demonstrated that glucocorticoids suppressed an interleukin‐1β‐driven inflammatory pathway for galectin‐1 expression in vitro and in vivo. Here, we show glucocorticoid‐mediated inhibitory mechanism against hypoxia‐inducible factor (HIF)‐1α‐involved galectin‐1 expression in human Müller glial cells and the retina of diabetic mice. Hypoxia‐induced increases in galectin‐1/LGALS1 expression and promoter activity were attenuated by dexamethasone and triamcinolone acetonide in vitro. Glucocorticoid application to hypoxia‐stimulated cells decreased HIF‐1α protein, but not mRNA, together with its DNA‐binding activity, while transactivating TSC22 domain family member (TSC22D)3 mRNA and protein expression. Co‐immunoprecipitation revealed that glucocorticoid‐transactivated TSC22D3 interacted with HIF‐1α, leading to degradation of hypoxia‐stabilized HIF‐1α via the ubiquitin‐proteasome pathway. Silencing TSC22D3 reversed glucocorticoid‐mediated ubiquitination of HIF‐1α and subsequent down‐regulation of HIF‐1α and galectin‐1/LGALS1 levels. Glucocorticoid treatment to mice significantly alleviated diabetes‐induced retinal HIF‐1α and galectin‐1/Lgals1 levels, while increasing TSC22D3 expression. Fibrovascular tissues from patients with proliferative DR demonstrated co‐localization of galectin‐1 and HIF‐1α in glial cells partially positive for TSC22D3. These results indicate that glucocorticoid‐transactivated TSC22D3 attenuates hypoxia‐ and diabetes‐induced retinal glial galectin‐1/LGALS1 expression via HIF‐1α destabilization, highlighting therapeutic implications for DR in the era of anti‐vascular endothelial growth factor treatment.     

Serum Uric Acid Is Associated with Left Ventricular Hypertrophy Independent of Serum Parathyroid Hormone in Male Cardiac Patients

Background

Several studies have shown that serum uric acid (UA) is associated with left ventricular (LV) hypertrophy. Serum levels of parathyroid hormone (PTH), which has bbe shown to be correlated with UA, is also known to be associated with cardiac hypertrophy; however, whether the association between UA and cardiac hypertrophy is independent of PTH remains unknown.

Purpose

We investigated whether the relationship between serum uric acid (UA) and LV hypertrophy is independent of intact PTH and other calcium-phosphate metabolism-related factors in cardiac patients.

Methods and Results

In a retrospective study, the association between UA and left ventricular mass index was assessed among 116 male cardiac patients (mean age 65±12 years) who were not taking UA lowering drugs. The median UA value was 5.9 mg/dL. Neither age nor body mass index differed significantly among the UA quartile groups. Patients with higher UA levels were more likely to be taking loop diuretics. UA showed a significant correlation with intact PTH (R = 0.34, P<0.001) but not with other calcium-phosphate metabolism-related factors. Linear regression analysis showed that log-transformed UA showed a significant association with left ventricular mass index, and this relationship was found to be significant exclusively in patients who were not taking loop and/or thiazide diuretics. Multivariate logistic regression analysis showed that log-transformed UA was independently associated with LV hypertrophy with an odds ratio of 2.79 (95% confidence interval 1.48–5.28, P = 0.002 per one standard deviation increase).

Conclusions

Among cardiac patients, serum UA was associated with LV hypertrophy, and this relationship was, at least in part, independent of intact PTH levels, which showed a significant correlation with UA in the same population.     

Periarticular Osteophytes as an Appendicular Joint Stress Marker (JSM): Analysis in a Contemporary Japanese Skeletal Collection

Objective

The aim of this study was to investigate the possibility that periarticular osteophytes plays a role as a appendicular joint stress marker (JSM) which reflects the biomechanical stresses on individuals and populations.

Methods

A total of 366 contemporary Japanese skeletons (231 males, 135 females) were examined closely to evaluate the periarticular osteophytes of six major joints, the shoulder, elbow, wrist, hip, knee, and ankle and osteophyte scores (OS) were determined using an original grading system. These scores were aggregated and analyzed statistically from some viewpoints.

Results

All of the OS for the respective joints were correlated logarithmically with the age-at-death of the individuals. For 70 individuals, in whom both sides of all six joints were evaluated without missing values, the age-standardized OS were calculated. A right side dominancy was recognized in the joints of the upper extremities, shoulder and wrist joints, and the bilateral correlations were large in the three joints on the lower extremity. For the shoulder joint and the hip joint, it was inferred by some distinctions that systemic factors were relatively large. All of these six joints could be assorted by the extent of systemic and local factors on osteophytes formation. Moreover, when the age-standardized OS of all the joints was summed up, some individuals had significantly high total scores, and others had significantly low total scores; namely, all of the individuals varied greatly in their systemic predisposition for osteophytes formation.

Conclusions

This study demonstrated the significance of periarticular osteophytes; the evaluating system for OS could be used to detect differences among joints and individuals. Periarticular osteophytes could be applied as an appendicular joint stress marker (JSM); by applying OS evaluating system for skeletal populations, intra-skeletal and inter-skeletal variations in biomechanical stresses throughout the lives could be clarified.