THE ROLE OF HSF1 PROTEIN REGULATION ON NEURODEGENERATION

Cellular protein homeostasis is achieved by a delicate network of molecular chaperones and various proteolytic processes such as ubiquitin–proteasome system (UPS) to avoid a build-up of misfolded protein aggregates. The latter is a common denominator of neurodegeneration. Neurons are found to be particularly vulnerable to toxic stress from aggregation-prone proteins such as α-synuclein. Induction of heat-shock proteins (HSPs), such as through activated heat shock transcription factor 1 (HSF1) via Hsp90 inhibition, is being investigated as a therapeutic option for proteinopathic diseases. HSF1 is a master stress-protective transcription factor which activates genes encoding protein chaperones (e.g. iHsp70) and anti-apoptotic proteins. However, whether and how HSF1 is dysregulated during neurodegeneration has not been studied. Here, we discover aberrant HSF1 degradation by aggregated α-synuclein (or α-synuclein-induced proteotoxic stress) in transfected neuroblastoma cells. HSF1 dysregulation via α-synuclein was confirmed by in vivo assessment of mouse and in situ studies of human specimens with α-synucleinopathy. We demonstrate that elevated NEDD4 is implicated as the responsible ubiquitin E3 ligase for HSF1 degradation through UPS. Furthermore, pharmacologically induced SIRT1-mediated deacetylation can attenuate aberrant NEDD4-mediated HSF1 degradation. Indeed, we define the acetylation status of the Lys 80 residue located in the DNA-binding domain of HSF1 as a critical factor in modulating HSF1 protein stability in addition to its previously identified role in the transcriptional activity. Together with the finding that preserving HSF1 can alleviate α-synuclein toxicity, the first part of the study strongly suggests that aberrant HSF1 degradation is a key neurodegenerative mechanism underlying α-synucleinopathy. Chronic activation of another cellular stress response, unfolded protein response in ER, has been implicated in tauopathy including Alzheimer’s disease (AD). The unfolded protein response (UPR) in the endoplasmic reticulum (ER) and the cytoplasmic heat stress response are two major stress response systems necessary for maintaining proteostasis for cellular health. Failure of either of these systems, such as in sustained UPR activation or in insufficient heat shock response activation, can lead to the development of neurodegeneration. Alleviation of ER stress and enhancement of heat shock response through heat shock factor 1 (HSF1) activation have previously been considered as attractive potential therapeutic targets for AD—a prevalent and devastating tauopathy. The second part of the study concentrates on our attempts to understand the interplay of the two aforementioned systems and their cooperative role in AD. We provide compelling in vitro and in vivo evidence that strongly suggests an auto-propagating interplay of UPR activation and HSF1 degradation being a common pathogenic feature in both human AD and tau transgenic mouse AD models. We identify aging-associated AD-like neuropathological changes in the hippocampus of HSF1 heterozygous knock-out mice. We speculate that HSF1 loss as an early (earliest) event which constitutes a mechanistic connection between ER stress and tau hyperphosphorylation in tau pathology. Finally, we demonstrate that aged mice lacking HSF1 gene exhibited deficits in hippocampal-dependent functions including short-term working memory, spatial learning and long-term memory. All together, our work supports a previously underappreciated importance of this master stress regulator HSF1 in neuronal functions and in maintaining brain homeostasis

Evaluating the Confluent Impact of Geology, Housing Characteristics, and Season on Indoor Radon in Atlanta Metropolitan Area, The United States

Radon is a radioactive gas that potentially causes lung cancer after long-term exposure. This thesis investigated the confluent impact of geology, housing characteristics, and season on indoor radonand identified the significant factors associated with elevated radon levels in Atlanta metropolitan area, USA. Using the data obtained from the private vendor, Air Chek, this study identified hot spots of high radon levels. The hot spots were found in Douglas, Fulton, DeKalb, and Gwinnett. Through binary logistic regression analysis, this study identified that the granite and orthogneiss bedrock, the ranch-style house, the presence of a basement, and the test in cold seasons were more likely to report test results above 4.0 pCi/L, the action level of radon recommended by the U.S. Environmental Protection Agency. This study may provide the decision-makers in local governments a valuable insight into establishing the radon policies for indoor radon testing and remediation to improve public health

Convergence in information and communication technology (ICT) using patent analysis

Since the 1990s, information and communication technology (ICT) has been perceived as the critical technology for economic development, and the ICT industry itself has been growing exceptionally fast. Moreover, technology convergence in ICT has received particular attention. ICT innovations diffuse into existing products and thus come to form a new integral part of the goods. This is an exploratory research to examine technology convergence of the supply side as a firm level in the ICT sector using International Patent Classification (IPC) of 43,636 sample patents from 1995 to 2008. This study finds a degree of merger and relationships between different technology domains through the association rule mining of patent co-classification. This type of analysis helps companies to take strategies under the environment of technological trajectory change

Important Features for Protein Foldings in Two Acyl Carrier Proteins from Enterococcus faecalis

The emergence of multi-drug resistant Enterococcus faecalis raises a serious threat to global public health. E. faecalis is a gram-positive intestinal commensal bacterium found in humans. E. faecalis can endure extreme environments such as high temperature, pressure, and high salt, which facilitates them to cause infection in hospitals. E. faecalis has two acyl carrier proteins, AcpA (EfAcpA) in de novo fatty acid synthesis (FAS) and AcpB (EfAcpB) which utilizes exogenous fatty acids. Previously, we determined the tertiary structures of these two ACPs and investigated their structure-function relationships. Solution structures revealed that overall folding of these two ACPs is similar to those of other bacterial ACPs. However, circular dichroism (CD) experiments showed that the melting temperature of EfAcpA is 76.3°C and that of EfAcpB is 79.2°C, which are much higher than those of other bacterial ACPs. In this study, to understand the origin of their structural stabilities, we verified the important residues for stable folding of these two ACPs by monitoring thermal and chemical denaturation. Hydrogen/deuterium exchange and chemical denaturation experiments on wild-type and mutant proteins revealed that Ile10 of EfAcpA and Ile14 of EfAcpB mediate compact intramolecular packing and promote high thermostability and stable folding. E. faecalis may maximize efficiency of FAS and increase adaptability to the environmental stress by having two thermostable ACPs. This study may provide insight into bacterial adaptability and development of antibiotics against multi-drug-resistant E. faecalis

Nonparametric and semiparametric methods in medical diagnostics

In medical diagnostics, biomarkers are used as the basis for detecting or predicting disease. There has been an increased interest in using the Receiver Operating Characteristic (ROC) curve to assess the accuracy of biomarkers. In many situations, a single biomarker is not sufficient for the desired level of accuracy; furthermore, newly discovered biomarkers can provide additional information for a specific disease. Even though numerous methods have been developed to evaluate a single biomarker, few statistical methods exist to accommodate multiple biomarkers simultaneously. The first paper proposes a semiparametric transformation model for multiple biomarkers in ROC analysis to optimize classification accuracy. This model assumes that some unknown and marker-specific transformations of biomarkers follow a multivariate normal distribution; it incorporates random effects to account for within-subject correlation among biomarkers. Nonparametric maximum likelihood estimation is used for inference, and the parameter estimators are shown to be asymptotically normal and semiparametrically efficient. The proposed method is applied to analyze brain tumor imaging data and prostate cancer data. In the second paper, we focus on assessing the accuracy of biomarkers by adjusting for covariates that can influence the performance of biomarkers. Therefore, we develop an accelerated ROC model in which the effect of covariates relates to rescaling the original ROC curve. The proposed model generalizes the usual accelerated failure time model in the survival context to the ROC analysis. An innovative method is developed to construct estimating equations for parameter estimation. The bootstrapping method is used for inference, and the parameter estimators are shown to be asymptotically normal. We apply the proposed method to data from a prostate cancer study. The paired-reader, paired-patient design is commonly used in reader studies when evaluating the diagnostic performance of radiological imaging systems. In this design, multiple readers interpret all test results of patients who undergo multiple diagnostic tests under study. In the third paper, we develop a method to estimate and compare accuracies of diagnostic tests in a paired-reader, paired-patient design by introducing a latent model for test results. The asymptotic property of the proposed test statistics is derived based on the theory of U-statistics. Furthermore, a method for correcting an imperfect gold standard bias and sample size formula are presented. The proposed method is applied to comparing the diagnostic performance of digital mammography and screen-film mammography in discriminating breast tumors

Ginsenoside Compound K Induces Ros-Mediated Apoptosis and Autophagic Inhibition in Human Neuroblastoma Cells In Vitro and In Vivo

Autophagy can result in cellular adaptation, as well as cell survival or cell death. Modulation of autophagy is increasingly regarded as a promising cancer therapeutic approach. Ginsenoside compound K (CK), an active metabolite of ginsenosides isolated from Panax ginseng C.A. Meyer, has been identified to inhibit growth of cancer cell lines. However, the molecular mechanisms of CK effects on autophagy and neuroblastoma cell death have not yet been investigated. In the present study, CK inhibited neuroblastoma cell proliferation in vitro and in vivo. Treatment by CK also induced the accumulation of sub-G1 population, and caspase-dependent apoptosis in neuroblastoma cells. In addition, CK promotes autophagosome accumulation by inducing early-stage autophagy but inhibits autophagic flux by blocking of autophagosome and lysosome fusion, the step of late-stage autophagy. This effect of CK appears to be mediated through the induction of intracellular reactive oxygen species (ROS) and mitochondria membrane potential loss. Moreover, chloroquine, an autophagy flux inhibitor, further promoted CK-induced apoptosis, mitochondrial ROS induction, and mitochondria damage. Interestingly, those promoted phenomena were rescued by co-treatment with a ROS scavenging agent and an autophagy inducer. Taken together, our findings suggest that ginsenoside CK induced ROS-mediated apoptosis and autophagic flux inhibition, and the combination of CK with chloroquine, a pharmacological inhibitor of autophagy, may be a novel therapeutic potential for the treatment of neuroblastoma

A Multi-Institution Look at College Students Seeking Counseling: Nature and Severity of Concerns

This study provides information about students seeking counseling (N = 3,844) at 9 institutions of higher education. The K-PIRS, an empirically validated measure, was used to assess 7 problem areas (Mood Difficulties, Learning Problems, Food Concerns, Interpersonal Conflicts, Career Uncertainties, Self-Harm Indicators, and Addiction Issues). Forty-two percent of students presented with multiple problems and most reported that their concerns interfered with their academic (87%) and social (90%) functioning. A majority of students (61%) were in a stage of contemplation when seeking counseling. Only 24% were in a stage of action. There were small differences in problem scores by participants’ gender, ethnicity, year in school, type of residence, work status, previous treatment, and use of psychiatric medication. Implications are discussed for counseling practitioners working with college students