Recombinant Klotho attenuates IFNγ receptor signaling and SAMHD1 expression through blocking NF-κB translocation in glomerular mesangial cells.

Interferon gamma (IFNγ) is a cytokine implicated in the pathogenesis of autoimmune diseases. SAM and HD domain-containing protein 1 (SAMHD1) is an IFNγ-inducible protein that modulates cellular dNTP levels. Mutations in the human SAMHD1 gene cause Aicardi-Goutières (AG) syndrome, an autoimmune disease sharing similar clinical features with systemic lupus erythematosus (SLE). Klotho is an anti-inflammatory protein which suppresses aging through multiple mechanisms. Implication of Klotho in autoimmune response is identified in rheumatologic diseases such as SLE. Little information exists regarding the effect of Klotho in lupus nephritis, one of the prevalent symptoms of SLE. The present study verified the effect of IFNγ on SAMHD1 and Klotho expression in MES-13 glomerular mesangial cells, a special cell type in glomerulus that is critically involved in lupus nephritis. IFNγ upregulated SAMHD1 expression in MES-13 cells through the Janus kinase-signal transducer and activator of transcription 1 (JAK-STAT1) and the nuclear factor kappa B (NFκB) signaling pathways. IFNγ decreased Klotho protein expression in MES-13 cells. Treatment of MES-13 cells with recombinant Klotho protein inhibited SAMHD1 expression by blocking IFNγ-induced NFκB nuclear translocation, but showed no effect on JAK-STAT1 signaling. Collectively, our findings support the protective role of Klotho in attenuating lupus nephritis through the inhibition of IFNγ-induced SAMHD1 expression and IFNγ downstream signaling in MES-13 cells.

Inhibitory Effects of Ursolic Acid on the Stemness and Progression of Human Breast Cancer Cells by Modulating Argonaute-2.

The stemness and metastasis of cancer cells are crucial features in determining cancer progression. Argonaute-2 (AGO2) overexpression was reported to be associated with microRNA (miRNA) biogenesis, supporting the self-renewal and differentiation characteristics of cancer stem cells (CSCs). Ursolic acid (UA), a triterpene compound, has multiple biological functions, including anticancer activity. In this study, we find that UA inhibits the proliferation of MDA-MB-231 and MCF-7 breast cancer cell lines using the CCK-8 assay. UA induced a significant decrease in the fraction of CSC in which it was examined by changes in the expression of stemness biomarkers, including the Nanog and Oct4 genes. UA altered invasion and migration capacities by significant decreases in the levels of epithelial-to-mesenchymal transition (EMT) proteins of slug and vimentin. Furthermore, the co-reduction in oncogenic miRNA levels (miR-9 and miR-221) was a result of the down-modulation in AGO2 in breast cancer cells in vitro. Mechanically, UA increases PTEN expression to inactivate the FAK/PI3K/Akt/mTOR signaling pathway and the decreased level of c-Myc in quantitative RT-PCR and Western blot imaging analyses. Our current understanding of the anticancer potential of UA in interrupting between EMT programming and the state of CSC suggests that UA can contribute to improvements in the clinical practice of breast cancer.

Induction of G2/M Phase Arrest by Diosgenin via Activation of Chk1 Kinase and Cdc25C Regulatory Pathways to Promote Apoptosis in Human Breast Cancer Cells.

The anti-tumor activity of diosgenin, a new steroidal constituent present in fenugreek, on two human breast cancer cell lines, MCF-7 and Hs578T, was studied. Diosgenin treatment resulted in cell growth inhibition, cell cycle arrest, and apoptosis in concentration- and time-dependent manners in both cell lines. Western blot analyses of whole cell lysates for cell cycle proteins showed that diosgenin altered phosphorylated cyclin checkpoint1 (p-Chk1Ser345) and cyclin B expression, which resulted in G2/M phase blockade. Mechanistically, Cdc25C-Cdc2 signaling was involved in inactivating Chk1Ser345 by p53-dependence in MCF-7 cells and p21-dependence in Hs578T cells that are p53-deficient. Moreover, diosgenin induced a significant loss of the mitochondrial membrane potential in breast cancer cells, and prominently affected cell death through down-regulation of the anti-apoptotic protein, Bcl-2. This released cytochrome c and activated the caspase signaling cascade. Taken together, these findings reveal that the anti-proliferative activity of diosgenin involves the induction of G2/M phase arrest via modulating the Cdc25C-Cdc2-cyclin B pathway and mitochondria-mediated apoptosis in human breast cancer cell lines. This suggests the potential usefulness of diosgenin in treating breast cancer.

Upregulation of PRMT6 by LPS suppresses Klotho expression through interaction with NF-κB in glomerular mesangial cells.

Lipopolysaccharide (LPS) released from gram-negative bacteria stimulates immune responses in infected cells. Epigenetic modifications such as DNA methylation and protein methylation modulate LPS-induced innate immune gene expressions. Expression of the Klotho protein decreased with LPS treatment in rats. In a cellular model, information regarding the effect of LPS on Klotho expression was meager. In the present study, we demonstrated that LPS triggered global DNA and protein methylation in glomerular mesangial MES-13 cells. LPS upregulated protein expressions of enzymes central to cellular methylation reactions, especially protein arginine methyltransferase 6 (PRMT6) in MES-13 cells. Expression of the Klotho protein was diminished by LPS and was restored by 5-Aza-2'-deoxycytidine (5-Aza-2'-dc), AMI-1, and ammonium pyrrolidinedithiocarbamate (PDTC), but not adenosine aldehyde (AdOx). NF-κB was identified as a substrate for arginine methylation and interacted with PRMT6 in MES-13 cells. Inhibition of PRMT activity by AMI-1 blocked LPS-induced NF-κB nuclear translocation in MES-13 cells. Our data indicate that NF-κB negatively regulated Klotho expression with an interaction with PRMT6, which was upregulated by LPS in MES-13 cells.

Increased Cellular Levels of MicroRNA-9 and MicroRNA-221 Correlate with Cancer Stemness and Predict Poor Outcome in Human Breast Cancer.

Background /Aims: Recent studies of microRNA (miRNA) involvement in tumorigenesis have indicated the critical role of these non-coding small RNAs in malignant transformation, but the prognostic role, if any, of miRNAs in breast cancer remains undetermined. Therefore, we assessed the prognostic significance of microRNA-9 (miR-9) and miR-221 in breast cancer toward the goal of understanding the contribution(s) of these miRNAs to cancer cell stemness. METHODS: The level of each of miR-9 and miR-221 in 206 paired laser capture microdissected tumor cells and non-tumor cells was determined by quantitative reverse transcription-PCR (qRT-PCR). The relationship between the miRNA signature and clinicopathological data and prognosis of breast cancer was assessed. Identification of a stem cell-enriched side population was achieved with fluorescence-activated cell sorting and a sphere-forming assay. Wound healing, Boyden chamber assays, and western blotting were used to study the contribution of each miRNA to tumor cell migration and invasion. RESULTS: We found that induction of miR-9 and miR-221 mimics conferred side-population cells to form spheroidal tumor colonies in suspension culture that maintained the mesenchymal stem-cell potential in non-invasive MCF-7 breast cancer cells. In contrast, knockdown of both miR-9 and miR-221 in invasive MDA-MB-231 breast cancer cells dramatically decreased the number of side-population colonies with stem cell-like potency, which reduced the capacity for tumor-cell renewal, invasion, and migration. Clinically, the mean proportion of miR-9- or miR-221-overexpressing cells was significantly greater in tumor cells compared with non-tumor cells (P < 0.05). Increased levels of miR-9 and miR-221 in breast tissue portended a significantly elevated risk of progression to malignancy with respect to larger tumor size, poor differentiation, late-stage evolution, lymph-node metastasis (P < 0.05), and lower overall survival (Ptrend = 0.017; eight-year follow-up). CONCLUSION: Our findings provide strong evidence that miR-9 and miR-221 can enhance the generation of cancer stem cells to yield an invasive phenotype and that overexpression of these miRNAs predicts a poor outcome for breast cancer patients.

A new rapid and efficient system with dominant selection developed to inactivate and conditionally express genes in Candida albicans.

Candida albicans is an important human fungal pathogen but its study has been hampered for being a natural diploid that lacks a complete sexual cycle. Gene knock-out and essential gene repression are used to study gene function in C. albicans. To effectively study essential genes in wild-type C. albicans, we took advantage of the compatible effects of the antibiotics hygromycin B and nourseothricin, the recyclable CaSAT1-flipper and the tetracycline-repressible (Tet-off) system. To allow deleting two alleles simultaneously, we created a cassette with a C. albicans HygB resistance gene (CaHygB) flanked with the FLP recombinase target sites that can be operated alongside the CaSAT1-flipper. Additionally, to enable conditionally switching off essential genes, we created a CaHygB-based Tet-off cassette that consisted of the CaTDH3 promoter, which is used for the constitutive expression of the tetracycline-regulated transactivator and a tetracycline response operator. To validate the new systems, all strains were constructed based on the wild-type strain and selected by the two dominant selectable markers, CaHygB and CaSAT1. The C. albicans general transcriptional activator CaGCN4 and its negative regulator CaPCL5 genes were targeted for gene deletion, and the essential cyclin-dependent kinase CaPHO85 gene was placed under the Tet-off system. Cagcn4, Capcl5, the conditional Tet-off CaPHO85 mutants, and mutants bearing two out of the three mutations were generated. By subjecting the mutants to various stress conditions, the functional relationship of the genes was revealed. This new system can efficiently delete genes and conditionally switch off essential genes in wild-type C. albicans to assess functional interaction between genes.

The differential roles of Slit2-exon 15 splicing variants in angiogenesis and HUVEC permeability.

Slit2, a secreted glycoprotein, is down-regulated in many cancers. Slit2/Robo signaling pathway plays an important, but controversial, role in angiogenesis. We identified splicing variants of Slit2 at exon 15, Slit2-WT and Slit2-ΔE15, with differential effects on proliferation and invasive capability of lung cancer cells. The aim of this study was to elucidate the differential roles of these exon 15 splicing variants in angiogenesis. Our results revealed that both Slit2-WT and Slit2-ΔE15 inhibit motility of human umbilical vein endothelial cells (HUVECs). The conditioned medium (CM) collected from CL1-5/VC or CL1-5/Slit2-WT lung adenocarcinoma cells blocked HUVEC tube formation and angiogenesis on chorioallantoic membrane (CAM) assay when compared with untreated HUVECs and CAM, respectively. However, CM of CL1-5/Slit2-ΔE15 restored the quality of tubes and the size of vessels. Although both Slit2-WT and Slit2-ΔE15 inhibited permeability induced by CM of cancer cells, Slit2-ΔE15 exhibited stronger effect. These results suggested that Slit2-ΔE15 plays important roles in normalization of blood vessels by enhancing tube quality and tightening endothelial cells, while Slit2-WT only enhances tightening of endothelial cells. It appears that Robo4 is responsible for Slit2 isoform-mediated inhibition of permeability, while neither Robo1 nor Robo4 is required for Slit2-ΔE15-enhanced tube quality. The results of this study suggest that Slit2-ΔE15 splicing form is a promising molecule for normalizing blood vessels around a tumor, which, in turn, may increase efficacy of chemotherapy and radiotherapy.

A role of Candida albicans CDC4 in the negative regulation of biofilm formation.

The CDC4 gene is nonessential in Candida albicans and plays a role in suppressing filamentous growth, in contrast to its homologues, which are involved in the G1-S transition of the cell cycle. While characterizing the function of C. albicans CDC4 (CaCDC4), we found that the loss of CaCDC4 resulted in a reduction in cell flocculation, indicating a possible role for CaCDC4 in biofilm formation. To elucidate the role of CaCDC4 in biofilm formation, Cacdc4 null mutant strains were constructed by using the mini-Ura-blaster method. To create a CaCDC4 rescued strain, the plasmid p6HF-ACT1p-CaCDC4 capable of constitutively expressing CaCDC4 was introduced into the Cacdc4 homozygous null mutant. To determine the biofilm formation ability, an in vitro XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium-5-carboxanilide) reduction assay was used. Compared with the parental auxotrophic strain BWP17, the Cacdc4 homozygous null mutant was able to enhance biofilm formation significantly. This enhancement of biofilm formation in the Cacdc4 homozygous null mutant could be reversed by constitutively expressing CaCDC4. We conclude that CaCDC4 has a role in suppressing biofilm formation in C. albicans.

Dissection of the Candida albicans Cdc4 protein reveals the involvement of domains in morphogenesis and cell flocculation.

BACKGROUND: CDC4, which encodes an F-box protein that is a member of the Skp1-Cdc53/Cul1-F-box (SCF) ubiquitin E3 ligase, was initially identified in the budding yeast Saccharomyces cerevisiae as an essential gene for progression through G1-S transition of the cell cycle. Although Candida albicans CDC4 (CaCDC4) can release the mitotic defect caused by the loss of CDC4 in S. cerevisiae, CaCDC4 is nonessential and suppresses filamentation. RESULTS: To further elucidate the function of CaCDC4, a C. albicans strain, with one CaCDC4 allele deleted and the other under the repressible C. albicans MET3 promoter (CaMET3p) control, was made before introducing cassettes capable of doxycycline (Dox)-induced expression of various C. albicans Cdc4 (CaCdc4) domains. Cells from each strain could express a specific CaCdc4 domain under Dox-induced, but CaMET3-CaCDC4 repressed conditions. Cells expressing domains without either the F-box or WD40-repeat exhibited filamentation and flocculation similarly to those lacking CaCDC4 expression, indicating the functional essentiality of the F-box and WD40-repeat. Notably, cells expressing the N-terminal 85-amino acid truncated CaCdc4 partially reverse the filament-to-yeast and weaken the ability to flocculate compared to those expressing the full-length CaCdc4, suggesting that N-terminal 85-amino acid of CaCdc4 regulates both morphogenesis and flocculation. CONCLUSIONS: The F-box and the WD40-repeat of CaCdc4 are essential in inhibiting yeast-to-filament transition and flocculation. The N-terminal region (1-85) of CaCdc4 also has a positive role for its function, lost of which impairs both the ability to flocculate and to reverse filamentous growth in C. albicans.

Prognostic significance of cyclin D1, ß-catenin, and MTA1 in patients with invasive ductal carcinoma of the breast.

BACKGROUND: To investigate markers for predicting breast cancer progression, we performed a candidate gene-based study that assessed expression change of three genes, cyclin D1, ß-catenin, and metastasis-associated protein-1 (MTA1), involving in aggressive phenotypes of cancerous cells, namely hyperproliferation, epithelial-mesenchymal transition, and global transcriptional regulation. METHODS: Specimens were from 150 enrolled female patients, with invasive ductal carcinoma, followed up for more than 10 years. mRNA expression of cyclin D1, ß-catenin, and MTA1 in cancerous and noncancerous cells microdissected from the primary tumor site was determined by quantitative real-time PCR. The relationship between mRNA expression levels of the genes and clinicopathologic features was assessed by statistical analysis. Disease-free and overall survival (DFS and OS) were analyzed by Kaplan-Meier analysis with log-rank test and a multivariate Cox regression model. RESULTS: Cyclin D1 was shown to be overexpressed in late-stage breast cancer (stage III/IV). Breast cancer with lymph node metastasis (LNM) showed significantly higher frequency of overexpressed cyclin D1, ß-catenin, and MTA1 (P < 0.05). Patients carrying greater numbers of overexpressed genes had joint effects on increased risk in tumors of advanced stages (P ( trend ) = 0.03) and LNM (P ( trend ) < 0.01). In the LNM-negative group, patients whose tumors with greater number of cyclin D1, ß-catenin, and MTA1 overexpressions were associated with poorer clinical outcomes, with hazard ratio of 14.79 for OS (P = 0.015) and 7.54 for DFS (P = 0.015) using multivariate Cox regression analysis during the 10-year follow-up. CONCLUSIONS: Higher expression of cyclin D1, ß-catenin, and MTA1 mRNAs in breast cancers may prove effective in predicting unfavorable outcomes of breast cancer.

Filament Negative Regulator CDC4 Suppresses Glycogen Phosphorylase Encoded GPH1 That Impacts the Cell Wall-Associated Features in Candida albicans.

We have previously identified Candida albicans GPH1 (orf19.7021) whose protein product was associated with C. albicans Cdc4. The GPH1 gene is a putative glycogen phosphorylase because its Saccharomyces cerevisiae homolog participates in glycogen catabolism, which involves the synthesis of ß-glucan of the fungal cell wall. We made a strain whose CaCDC4 expression is repressed, and GPH1 is constitutively expressed. We established a GPH1 null mutant strain and used it to conduct the in vitro virulence assays that detect cell wall function. The in vitro virulence assay is centered on biofilm formation in which analytic procedures are implemented to evaluate cell surface hydrophobicity; competence, either in stress resistance, germ tube formation, or fibronection association; and the XTT-based adhesion and biofilm formation. We showed that the constitutively expressed GPH1 partially suppresses filamentation when the CaCDC4 expression is repressed. The C. albicans Gph1 protein is reduced in the presence of CaCdc4 in comparison with the absence of CaCdc4. Compared with the wild-type strain, the gph1Δ/gph1Δ mutant displayed a reduction in the capability to form germ tubes and the cell surface hydrophobicity but an increase in binding with fibronectin. Compared with the wild-type strain, the gph1Δ/gph1Δ mutant showed a rise in adhesion, the initial stage of biofilm formation, but displayed a similar capacity to form a mature biofilm. There was no major impact on the gph1Δ/gph1Δ mutant regarding the conditions of cell wall damaging and TOR pathway-associated nutrient depletion. We conclude that GPH1, adversely regulated by the filament suppressor CDC4, contributes to cell wall function in C. albicans.

Construction of Candida albicans Tet-on tagging vectors with a Ura-blaster cassette.

It has been difficult to develop molecular tools for studying the fungal pathogen Candida albicans because this species uses a non-standard genetic code and is diploid without a complete sexual cycle. Vector systems with regulatable promoters to produce conditional mutants, epitope tags for protein detection and recyclable selection markers are useful for functional study of genes. However, most currently available vectors contain only a subset of desired properties, which limits their application. To combine several useful properties in one vector, the vector pTET25 was initially modified into pTET25M, so that the URA3 gene flanked by dpl200 could be used repetitively. To enable more choices for cloning, a multiple cloning site was introduced at both ends of GFP in pTET25M. GFP expression was induced by doxycycline in a dose- and time-dependent manner when the plasmid was introduced into C. albicans with or without URA3. The applicability of the vectors was verified by constructing strains capable of expressing either the N-terminal GFP fusion of Cdc10 or the C-terminal GFP fusion of Cdc11. Additionally, by replacing the GFP gene of pTET25M with DNA sequence encoding Cdc10 with an epitope tag of six histidine residues at the C-terminus, doxycycline-induced expression of CDC10 was achieved when the expression vector was introduced into C. albicans. This new system allows for inducible expression of a desired C. albicans gene with the advantage of convenience of cloning. It also allows the presence of a recyclable URA3 marker and the detectable expression of fusion or epitope-tagged protein.

Novel mutations in the connexin43 (GJA1) and GJA1 pseudogene may contribute to nonsyndromic hearing loss.

Connexins (CXs), a large family of membrane proteins, are key components of gap junction channels. Among a cohort of patients with nonsyndromic hearing loss, we have recently identified three novel missense mutations in the GJA1 gene and GJA1 pseudogene (rhoGJA1) as likely being causally related to hearing loss. However, the functional alteration of CX43 caused by the mutations of GJA1 and rhoGJA1 gene remains unclear. This study compares the intracellular distribution and assembly of three CX43 mutants expressed in HeLa cells with their wild-type (WT) counterparts and the effects of the mutant proteins on those cells. Localization assay of WT CX43 reveals a typical punctuate fluorescence pattern of a gap junction channel between neighboring expression cells. Additionally, immunoblotting analysis of the transfectants confirms the production of mutant proteins, in which their distributions along appositional membranes are determined using immunofluorescent staining procedures. Furthermore, dye transfer assay results demonstrate that gap junctional intercellular communication is less in HeLa cells carrying mutant GJA1 or rhoGJA1 gene than in WT-expressing cells. The results of this study suggest that the three mutations in GJA1 or rhoGJA1 that we previously reported result in at least partial loss of normal functions carried out by CX43, which may form a basis for the mechanism contributing to hearing loss in patients.

Affinity purification of Candida albicans CaCdc4-associated proteins reveals the presence of novel proteins involved in morphogenesis.

Candida albicans CDC4 is nonessential and plays a role in suppressing filamentous growth, in contrast to its evolutionary counterparts involved in the G1-S transition of the cell cycle. Genetic epistasis analysis has indicated that proteins besides Sol1 are targets of C. albicans Cdc4. Moreover, no formal evidence suggests that C. albicans Cdc4 functions through the ubiquitin E3 ligase of the Skp1-Cul1/Cdc53-F-box complex. To elucidate the role of C. albicans CDC4, C. albicans Cdc4-associated proteins were sought by affinity purification. A 6xHis epitope-tagged C. albicans Cdc4 expressed from Escherichia coli was used in affinity purifications with the cell lysate of C. albicans cdc4 homozygous null mutant. Candida albicans Cdc4 and its associated proteins were resolved by SDS-PAGE and visualized by silver staining. The candidate proteins were recovered and trypsin-digested to generate MALDI-TOF spectra profiles, which were used to search against those of known proteins in the database to reveal their identities. Two out of four proteins encoded by GPH1 and THR1 genes were further verified to interact with C. albicans Cdc4 using a yeast two-hybrid assay. We conclude that in vitro affinity purification using C. albicans Cdc4 generated from E. coli as the bait and proteins from cell lysate of C. albicans cdc4 homozygous null mutant as a source of prey permit the identification of novel proteins that physically interact and functionally associate with C. albicans Cdc4.

Establishment of tetracycline-regulated bimolecular fluorescence complementation assay to detect protein-protein interactions in Candida albicans.

To visualize protein-protein interactions in Candida albicans with the bimolecular fluorescence complementation (BiFC) approach, we created a Tet-on system with the plasmids pWTN1 and pWTN2. Both plasmids bear a hygromycin B-resistant marker (CaHygB) that is compatible with the original Tet-on plasmid pNIM1, which carries a nourseothricin-resistant marker (CaSAT1). By using GFPmut2 and mCherry as reporters, we found that the two complementary Tet-on plasmids act synergistically in C. albicans with doxycycline in a dose-dependent manner and that expression of the fusion proteins, CaCdc11-GFPmut2 and mCherry-CaCdc10, derived from this system, is septum targeted. Furthermore, to allow detection of protein-protein interactions with the reassembly of a split fluorescent protein, we incorporated mCherry into our system. We generated pWTN1-RN and pNIM1-RC, which express the N-terminus (amino acids 1-159) and C-terminus (amino acids 160-237) of mCherry, respectively. To verify BiFC with mCherry, we created the pWTN1-CDC42-RN (or pWTN1-RN-CDC42) and pNIM1-RC-RDI1 plasmids. C. albicans cells containing these plasmids treated with doxycycline co-expressed the N- and C-terminal fragments of mCherry either N-terminally or C-terminally fused with CaCdc42 and CaRdi1, respectively, and the CaCdc42-CaRdi1 interaction reconstituted a functional form of mCherry. The establishment of this Tet-on-based BiFC system in C. albicans should facilitate the exploration of protein-protein interactions under a variety of conditions.

THR1 mediates GCN4 and CDC4 to link morphogenesis with nutrient sensing and the stress response in Candida albicans.

Candida albicans (C. albicans) CDC4 (CaCDC4), encoding the F­box protein for the substrate specificity of the Skp1­cullin­F­box E3 ubiquitin ligase complex, suppresses the yeast­to­filament transition in C. albicans. In our previous study, Thr1 was identified as a CaCdc4­associated protein using affinity purification. THR1 encodes a homoserine kinase, which is involved in the threonine biosynthesis pathway. The present study generated a strain with repressible CaCDC4 expression and continuous THR1 expression. Colony and cell morphology analyses, as well as immunoblotting, revealed that the Thr1 protein was detectable under conditions in which the expression of CaCDC4 was repressed and that the filaments resulting from the repressed expression of CaCDC4 were suppressed by the constitutive expression of THR1 in C. albicans. Additionally, by using the CaSAT1­flipper method, the present study produced null mutants of THR1, GCN4, and CaCDC4. The phenotypic consequences were evaluated by growth curves, spotting assays, microscopic analysis, reverse transcription­polymerase chain reaction and XTT­based biofilm formation ability. The results revealed that fewer cells lacking THR1 entered the stationary phase but had no apparent morphological alteration. It was observed that the expression of THR1 was upregulated concurrently with GCN4 during nutrient depletion and that cells lacking GCN4 rescued the lethality of cells in the absence of THR1 in conditions accumulating homoserine in the threonine biosynthesis pathway. Of note, it was found that cells with either CaCDC4 or THR1 loss were sensitive to oxidative stress and osmotic stress, with those with THR1 loss being more sensitive. In addition, it was observed that cells with loss of either CaCDC4 or THR1 exhibited the ability to increase biofilm formation, with those lacking CaCDC4 exhibiting a greater extent of enhancement. It was concluded that CaCDC4 is important in the coordination of morphogenesis, nutrient sensing, and the stress response through THR1 in C. albicans.

Pesticide exposure on southwestern Taiwanese with MnSOD and NQO1 polymorphisms is associated with increased risk of Parkinson's disease.

BACKGROUND: Hypothetic mechanism of the individual vulnerability to oxidative stress through metabolism of environmental xenobiotics and genotypic polymorphisms has been considered to promote the development of Parkinson's disease (PD). In this case-control study, we determined the role of manganese-containing superoxide dismutase (MnSOD) and NAD(P)H: quinone oxidoreductase 1 (NQO1) genes in PD risk in a population with high prevalence of pesticide exposure. METHODS: From southwestern region of Taiwan, we enrolled 153 patients with idiopathic PD and 155 healthy control subjects matched for age, sex and origin. Detailed questionnaires of face-to-face interviews among these subjects were collected. PCR-based restriction fragment length polymorphism (RFLP) assays were used to determine the genotypes of MnSOD (-9 T>C) and NQO1 (609 C>T) genes. RESULTS: Exposure to pesticides associated with PD was significant among patients with an increased odds ratio (OR) of 1.69 (95%CI, 1.07-2.65), and this association remained significant after adjustment for age, sex, and cigarette smoking (aOR=1.68, 95%CI, 1.03-2.76, P=0.023). Considering genetic factors, there were no significant differences in frequencies of both genotypes of MnSOD and NQO1 polymorphisms between PD patients and the control subjects (P>0.05). However, this difference in genotype distribution was significant among subjects who had been exposed to pesticide, with aOR of 2.49 (95%CI, 1.18-5.26, P=0.0072) for MnSOD C allele and aOR of 2.42 (95%CI, 1.16-4.76, P=0.0089) for NQO1 T allele, respectively. Moreover, among subjects exposed to pesticide, the combined MnSOD/NQO1 variant genotype was significantly associated with a 4.09-fold increased risk of PD (95%CI, 1.34-10.64, P=0.0052). CONCLUSION: Susceptible variants of MnSOD and NQO1 genes may interact with occupational pesticide exposure to increase PD risk in southwestern Taiwanese.

Cinnamomum osmophloeum Kanehira ethanol extracts prevents human liver-derived HepG2 cell death from oxidation stress by induction of ghrelin gene expression.

Diabetes patients associated with liver disease carry a significant risk of morbidity and mortality. Cinnamon has been reported to reduce fructose-induced oxidative stress in the rat liver. However, the mechanism by which cinnamon protects the liver in a high-saccharide environment remains to be investigated. HepG2 cells were cultured with 30 mM D-ribose to mimic the high-oxidative-stress environment, typical of a liver in a diabetic patient. Three different chemical types of C. osmophloeum ethanol extracts (CEEs) were added in HepG2 culture media and the administration of all three CEEs protected HepG2 cells from D-ribose damage and increased cell survival by approximately 20 percent. Exclusively, the transcript variant 1 of the ghrelin gene, but not variant 3, was 2-3 times induced by the addition of these CEEs. Moreover, the mRNAs of ghrelin processing enzyme, furin, and mboat4 were detected in HepG2 cells. The ghrelin hormones in the culture media were increased 4-9 times by the addition of CEEs. The protective effects of ghrelin on HepG2 cells in D-ribose environment were further confirmed by recombinant ghrelin transfection. We conclude that the CEEs induce ghrelin gene expression and protect HepG2 cells from D-ribose-induced oxidative damage through ghrelin signalling.

Association of eNOS and Cav-1 gene polymorphisms with susceptibility risk of large artery atherosclerotic stroke.

Endothelial nitric oxide synthase (eNOS) is localized in caveole and has important effects on caveolar coordination through its interaction with caveolin-1 (Cav-1), which supports normal functioning of vascular endothelial cells. However, the relationship between genotypic polymorphisms of e-NOS and Cav-1 genes and ischemic stroke (IS) remains lesser reported. This hospital-based case-control study aimed to determine the genetic polymorphisms of the eNOS (Glu298Asp) and Cav-1 (G14713A and T29107A) genes in association with susceptibility risk in patients who had suffered from a large artery atherosclerotic (LAA) stroke. Genotyping determination for these variant alleles was performed using the TaqMan assay. The distributions of observed allelic and genotypic frequencies for the polymorphisms were in Hardy-Weinberg equilibrium in healthy controls. The risk for an LAA stroke in the Asp298 variant was 1.72 (95% CI = 1.09-2.75) versus Glu298 of the eNOS. In the GA/AA (rs3807987) variant, it was 1.79 (95% CI = 1.16-2.74) versus GG and in TA/AA (rs7804372) was 1.61 (95% CI = 1.06-2.43) versus TT of the Cav-1, respectively. A tendency toward an increased LAA stroke risk was significant in carriers with the eNOS Glu298Asp variant in conjunction with the G14713 A and T29107A polymorphisms of the Cav-1 (aOR = 2.03, P-trend = 0.002). A synergistic effect between eNOS and Cav-1 polymorphisms on IS risk elevation was significantly influenced by alcohol drinking, heavy cigarette smoking (P-trend<0.01), and hypercholesterolemia (P-trend < 0.001). In conclusion, genotypic polymorphisms of the eNOS Glu298Asp and Cav-1 14713A/29107A polymorphisms are associated with the elevated risk of LAA stroke among Han Chinese in Taiwan.

Candida albicans Dbf4-dependent Cdc7 kinase plays a novel role in the inhibition of hyphal development.

Candida albicans is an opportunistic human fungal pathogen. The ability to switch among multiple cellular forms is key to its pathogenesis. The Dbf4-dependent protein kinase gene CDC7 is conserved due to its role in initiating DNA replication. Because a C. albicans Cdc7 (Cacdc7) homozygous null was not viable, we generated a C. albicans strain with a deleted C. albicans CDC7 (CaCDC7) allele and an expression-repressible allele. Surprisingly, cells of the strain grew as hyphae under the repressed conditions. The in vitro kinase assays confirmed that CaCdc7 (K232) and CaCdc7 (T437) are critical for catalytic and phosphoacceptor of activation activity, respectively. C. albicans cells formed hyphae when expressing either the catalytically inactive CaCdc7 (K232R) or the phosphoacceptor-deficient CaCdc7 (T437A). While CaCdc7 interacted with CaDbf4, cells of the strain in which CaCDC7 was repressed were not rescued by constitutively expressing C. albicans DBF4 or vice versa. We conclude that CaDBF4-dependent CaCDC7 is an essential gene suppressing the hyphal development.