Recent Research Articles from UNTHSC

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High glucose and diabetes enhanced store-operated Ca(2+) entry and increased expression of its signaling proteins in mesangial cells.

Sat, 06/21/2014 - 4:06am
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High glucose and diabetes enhanced store-operated Ca(2+) entry and increased expression of its signaling proteins in mesangial cells.

Am J Physiol Renal Physiol. 2014 May 1;306(9):F1069-80

Authors: Chaudhari S, Wu P, Wang Y, Ding Y, Yuan J, Begg M, Ma R

Abstract
The present study was conducted to determine whether and how store-operated Ca(2+) entry (SOCE) in glomerular mesangial cells (MCs) was altered by high glucose (HG) and diabetes. Human MCs were treated with either normal glucose or HG for different time periods. Cyclopiazonic acid-induced SOCE was significantly greater in the MCs with 7-day HG treatment and the response was completely abolished by GSK-7975A, a selective inhibitor of store-operated Ca(2+) channels. Similarly, the inositol 1,4,5-trisphosphate-induced store-operated Ca(2+) currents were significantly enhanced in the MCs treated with HG for 7 days, and the enhanced response was abolished by both GSK-7975A and La(3+). In contrast, receptor-operated Ca(2+) entry in MCs was significantly reduced by HG treatment. Western blotting showed that HG increased the expression levels of STIM1 and Orai1 in cultured MCs. A significant HG effect occurred at a concentration as low as 10 mM, but required a minimum of 7 days. The HG effect in cultured MCs was recapitulated in renal glomeruli/cortex of both type I and II diabetic rats. Furthermore, quantitative real-time RT-PCR revealed that a 6-day HG treatment significantly increased the mRNA expression level of STIM1. However, the expressions of STIM2 and Orai1 transcripts were not affected by HG. Taken together, these results suggest that HG/diabetes enhanced SOCE in MCs by increasing STIM1/Orai1 protein expressions. HG upregulates STIM1 by promoting its transcription but increases Orai1 protein through a posttranscriptional mechanism.

PMID: 24623143 [PubMed - indexed for MEDLINE]

Role of the p63-FoxN1 regulatory axis in thymic epithelial cell homeostasis during aging.

Fri, 06/20/2014 - 4:05am
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Role of the p63-FoxN1 regulatory axis in thymic epithelial cell homeostasis during aging.

Cell Death Dis. 2013;4:e932

Authors: Burnley P, Rahman M, Wang H, Zhang Z, Sun X, Zhuge Q, Su DM

Abstract
The p63 gene regulates thymic epithelial cell (TEC) proliferation, whereas FoxN1 regulates their differentiation. However, their collaborative role in the regulation of TEC homeostasis during thymic aging is largely unknown. In murine models, the proportion of TAp63(+), but not ΔNp63(+), TECs was increased with age, which was associated with an age-related increase in senescent cell clusters, characterized by SA-β-Gal(+) and p21(+) cells. Intrathymic infusion of exogenous TAp63 cDNA into young wild-type (WT) mice led to an increase in senescent cell clusters. Blockade of TEC differentiation via conditional FoxN1 gene knockout accelerated the appearance of this phenotype to early middle age, whereas intrathymic infusion of exogenous FoxN1 cDNA into aged WT mice brought only a modest reduction in the proportion of TAp63(+) TECs, but an increase in ΔNp63(+) TECs in the partially rejuvenated thymus. Meanwhile, we found that the increased TAp63(+) population contained a high proportion of phosphorylated-p53 TECs, which may be involved in the induction of cellular senescence. Thus, TAp63 levels are positively correlated with TEC senescence but inversely correlated with expression of FoxN1 and FoxN1-regulated TEC differentiation. Thereby, the p63-FoxN1 regulatory axis in regulation of postnatal TEC homeostasis has been revealed.

PMID: 24263106 [PubMed - indexed for MEDLINE]

Nanoparticle-mediated catalase delivery protects human neurons from oxidative stress.

Fri, 06/20/2014 - 4:05am
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Nanoparticle-mediated catalase delivery protects human neurons from oxidative stress.

Cell Death Dis. 2013;4:e903

Authors: Singhal A, Morris VB, Labhasetwar V, Ghorpade A

Abstract
Several neurodegenerative diseases and brain injury involve reactive oxygen species and implicate oxidative stress in disease mechanisms. Hydrogen peroxide (H2O2) formation due to mitochondrial superoxide leakage perpetuates oxidative stress in neuronal injury. Catalase, an H2O2-degrading enzyme, thus remains an important antioxidant therapy target. However, catalase therapy is restricted by its labile nature and inadequate delivery. Here, a nanotechnology approach was evaluated using catalase-loaded, poly(lactic co-glycolic acid) nanoparticles (NPs) in human neuronal protection against oxidative damage. This study showed highly efficient catalase encapsulation capable of retaining ~99% enzymatic activity. NPs released catalase rapidly, and antioxidant activity was sustained for over a month. NP uptake in human neurons was rapid and nontoxic. Although human neurons were highly sensitive to H2O2, NP-mediated catalase delivery successfully protected cultured neurons from H2O2-induced oxidative stress. Catalase-loaded NPs significantly reduced H2O2-induced protein oxidation, DNA damage, mitochondrial membrane transition pore opening and loss of cell membrane integrity and restored neuronal morphology, neurite network and microtubule-associated protein-2 levels. Further, catalase-loaded NPs improved neuronal recovery from H2O2 pre-exposure better than free catalase, suggesting possible applications in ameliorating stroke-relevant oxidative stress. Brain targeting of catalase-loaded NPs may find wide therapeutic applications for oxidative stress-associated acute and chronic neurodegenerative disorders.

PMID: 24201802 [PubMed - indexed for MEDLINE]

Combining Select Neuropsychological Assessment with Blood-Based Biomarkers to Detect Mild Alzheimer's Disease: A Molecular Neuropsychology Approach.

Fri, 06/13/2014 - 4:04am
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Combining Select Neuropsychological Assessment with Blood-Based Biomarkers to Detect Mild Alzheimer's Disease: A Molecular Neuropsychology Approach.

J Alzheimers Dis. 2014 Jun 10;

Authors: Edwards M, Balldin VH, Hall J, O'Bryant S

Abstract
Background: Current work has sought to establish a rapid and cost effective means of screening for Alzheimer's disease (AD) with the most recent findings showing utility of integrating blood-based biomarkers with cognitive measures. Objective: The current project sought to create a combined biomarker-cognitive profile to detect mild AD. Methods: Data was analyzed from 266 participants (129 AD cases [Early AD n = 93; Very Early AD n = 36]; 137 controls) enrolled in the Texas Alzheimer's Research and Care Consortium (TARCC). Non-fasting serum samples were collected from each participant and assayed via a multi-plex biomarker assay platform using electrochemiluminescence. Logistic Regression was utilized to detect early AD using two serum biomarkers (TNFα and IL7), demographic information (age), and one neuropsychological measure (Clock 4-point) as predictor variable. Disease severity was determined via Clinical Dementia Rating (CDR) scale global scores. Results: In the total sample (all levels of CDR scores), the combination of biomarkers, cognitive test score, and demographics yielded the obtained sensitivity (SN) of 0.94, specificity (SP) of 0.90, and an overall accuracy of 0.92. When examining early AD cases (i.e.m CDR = 0.5-1), the biomarker-cognitive profile yielded SN of 0.94, SP of 0.85, and an overall accuracy of 0.91. When restricted to very early AD cases (i.e., CDR = 0.5), the biomarker-cognitive profile yielded SN of 0.97 and SP of 0.72, with an overall accuracy of 0.91. Conclusions: The combination of demographics, two biomarkers, and one cognitive test created a biomarker-cognitive profile that was highly accurate in detecting the presence of AD, even in the very early stages.

PMID: 24916542 [PubMed - as supplied by publisher]

Rad5 template switch pathway of DNA damage tolerance determines synergism between cisplatin and NSC109268 in Saccharomyces cerevisiae.

Fri, 06/13/2014 - 4:04am
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Rad5 template switch pathway of DNA damage tolerance determines synergism between cisplatin and NSC109268 in Saccharomyces cerevisiae.

PLoS One. 2013;8(10):e77666

Authors: Jain D, Siede W

Abstract
The success of cisplatin (CP) based therapy is often hindered by acquisition of CP resistance. We isolated NSC109268 as a compound altering cellular sensitivity to DNA damaging agents. Previous investigation revealed an enhancement of CP sensitivity by NSC109268 in wild-type Saccharomyces cerevisiae and CP-sensitive and -resistant cancer cell lines that correlated with a slower S phase traversal. Here, we extended these studies to determine the target pathway(s) of NSC109268 in mediating CP sensitization, using yeast as a model. We reasoned that mutants defective in the relevant target of NSC109268 should be hypersensitive to CP and the sensitization effect by NSC109268 should be absent or strongly reduced. A survey of various yeast deletion mutants converged on the Rad5 pathway of DNA damage tolerance by template switching as the likely target pathway of NSC109268 in mediating cellular sensitization to CP. Additionally, cell cycle delays following CP treatment were not synergistically influenced by NSC109268 in the CP hypersensitive rad5Δ mutant. The involvement of the known inhibitory activities of NSC109268 on 20S proteasome and phosphatases 2Cα and 2A was tested. In the CP hypersensitive ptc2Δptc3Δpph3Δ yeast strain, deficient for 2C and 2A-type phosphatases, cellular sensitization to CP by NSC109268 was greatly reduced. It is therefore suggested that NSC109268 affects CP sensitivity by inhibiting the activity of unknown protein(s) whose dephosphorylation is required for the template switch pathway.

PMID: 24130896 [PubMed - indexed for MEDLINE]