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author:("Xu, zhucheng")
1.  Expression of leucine-rich repeat kinase 2 (LRRK2) inhibits the processing of uMtCK to induce cell death in a cell culture model system 
Bioscience reports  2011;31(5):429-437.
PD (Parkinson’s disease) is the most common neurodegenerative movement disorder. Mutations in LRRK2 (leucine-rich repeat kinase 2) gene are linked to the most common inherited and sporadic PD. Overexpression of LRRK2 and its mutants could induce mitochondrial-dependent neuronal apoptosis. However, the underlying mechanism remains elusive. We have identified several novel LRRK2 interacting proteins and showed that LRRK2 can interact with three components of the PTPC (permeability transition pore complex) including ANT (adenine nucleotide translocator), VDAC (voltage-dependent anion channel) and uMtCK [ubiquitous MtCK (mitochondrial creatine kinase)]. Those components have been reported to be involved in the permeability of mitochondrial membrane. We provide evidence that LRRK2 is likely to interact with uMtCK directly and expression of LRRK2 and its mutant form can suppress the processing of the immature form of uMtCK. LRRK2 expression keeps the uMtCK preprotein on the outer mitochondrial membrane instead of entering the mitochondria. In addition, the expression of both wild-type and mutant forms of LRRK2 promotes the interaction between ANT and VDAC, which plays a role in permeabilization transition pore opening. Finally, LRRK2-induced cell death can be suppressed by uMtCK. Our findings imply that LRRK2 can interact directly with uMtCK to block its entry into mitochondria and its subsequent processing, resulting in inhibition of mitochondrial energy channelling. Meanwhile, the decrease of uMtCK in mitochondria results in elevated interaction between ANT and VDAC and leads to neuronal apoptosis. Thus, our study provides the rational for clinical trials using creatine to treat PD and supports the notion of exploiting LRRK2 as a drug target for PD.
PMCID: PMC3971885  PMID: 21370995
apoptosis; leucine-rich repeat kinase 2 (LRRK2); mitochondria; Parkinson’s disease (PD); permeability transition pore complex (PTPC)
2.  Application of change point analysis to daily influenza-like illness emergency department visits 
The utility of healthcare utilization data from US emergency departments (EDs) for rapid monitoring of changes in influenza-like illness (ILI) activity was highlighted during the recent influenza A (H1N1) pandemic. Monitoring has tended to rely on detection algorithms, such as the Early Aberration Reporting System (EARS), which are limited in their ability to detect subtle changes and identify disease trends.
To evaluate a complementary approach, change point analysis (CPA), for detecting changes in the incidence of ED visits due to ILI.
Methodology and principal findings
Data collected through the Distribute project (, which aggregates data on ED visits for ILI from over 50 syndromic surveillance systems operated by state or local public health departments were used. The performance was compared of the cumulative sum (CUSUM) CPA method in combination with EARS and the performance of three CPA methods (CUSUM, structural change model and Bayesian) in detecting change points in daily time-series data from four contiguous US states participating in the Distribute network. Simulation data were generated to assess the impact of autocorrelation inherent in these time-series data on CPA performance. The CUSUM CPA method was robust in detecting change points with respect to autocorrelation in time-series data (coverage rates at 90% when −0.2≤ρ≤0.2 and 80% when −0.5≤ρ≤0.5). During the 2008–9 season, 21 change points were detected and ILI trends increased significantly after 12 of these change points and decreased nine times. In the 2009–10 flu season, we detected 11 change points and ILI trends increased significantly after two of these change points and decreased nine times. Using CPA combined with EARS to analyze automatically daily ED-based ILI data, a significant increase was detected of 3% in ILI on April 27, 2009, followed by multiple anomalies in the ensuing days, suggesting the onset of the H1N1 pandemic in the four contiguous states.
Conclusions and significance
As a complementary approach to EARS and other aberration detection methods, the CPA method can be used as a tool to detect subtle changes in time-series data more effectively and determine the moving direction (ie, up, down, or stable) in ILI trends between change points. The combined use of EARS and CPA might greatly improve the accuracy of outbreak detection in syndromic surveillance systems.
PMCID: PMC3534458  PMID: 22759619
Surveillance; public health; disease; outbreaks; algorithm; change point analysis; Simulation of complex systems (at all levels: molecules to work groups to organizations); monitoring the health of populations; detecting disease outbreaks and biological threats
3.  Self-reported fever and measured temperature in emergency department records used for syndromic surveillance 
Many public health agencies monitor population health using syndromic surveillance, generally employing information from emergency department (ED) visit records. When combined with other information, objective evidence of fever may enhance the accuracy with which surveillance systems detect syndromes of interest, such as influenza-like illness. This study found that patient chief complaint of self-reported fever was more readily available in ED records than measured temperature and that the majority of patients with an elevated temperature recorded also self-reported fever. Due to its currently limited availability, we conclude that measured temperature is likely to add little value to self-reported fever in syndromic surveillance for febrile illness using ED records.
PMCID: PMC3422841  PMID: 22596079
Syndromic surveillance; measured temperature; BioSense; public health informatics; emergency department; surveillance; public health; disease; outbreaks; algorithm; simulation of complex systems (at all levels: molecules to work groups to organizations); monitoring the health of populations; detecting disease outbreaks and biological threats; change point analysis; user-centered design
4.  Phase II and Coagulation Cascade Biomarker Study of Bevacizumab with or without Docetaxel in Patients with Previously Treated Metastatic Pancreatic Adenocarcinoma 
Treatment options are limited for advanced pancreatic cancer progressive after gemcitabine therapy. The vascular endothelial growth factor (VEGF) pathway is biologically important in pancreatic cancer, and docetaxel has modest anti-tumor activity. We evaluated the role of the anti-VEGF antibody bevacizumab as second-line treatment for patients with metastatic pancreatic cancer.
Patients with metastatic adenocarcinoma of the pancreas who had progressive disease on a gemcitabine-containing regimen were randomized to receive bevacizumab alone or bevacizumab in combination with docetaxel.
Thirty-two patients were enrolled; 16 to bevacizumab alone (Arm A) and 16 to bevacizumab plus docetaxel (Arm B). Toxicities were greater in Arm B with the most common grade 3/4 nonhematologic toxicities including fatigue, diarrhea, dehydration and anorexia. No confirmed objective responses were observed. At 4 months, 2/16 patients in Arm A and 3/16 in Arm B were free from progression. The study was stopped according to the early stopping rule for futility. Median PFS and OS were 43 days and 165 days in Arm A and 48 days and 125 days in Arm B. Elevated D-dimer levels and thrombin-antithrombin complexes were associated with decreased survival and increased toxicity.
Bevacizumab with or without docetaxel does not have antitumor activity in gemcitabine-refractory metastatic pancreatic cancer. Baseline and on-treatment D-dimer and thrombin-antithrombin complex levels are associated with increased toxicity and decreased survival.
PMCID: PMC3030655  PMID: 20458210
5.  Phosphorylated Eukaryotic Translation Initiation Factor 4 (eIF4E) is Elevated in Human Cancer Tissues 
Cancer biology & therapy  2009;8(15):1463-1469.
Eukaryotic translation initiation factor 4E (eIF4E) is a rate-limiting factor for cap-dependent protein synthesis and is regulated by PI3 kinase/mTOR and mitogen-activated protein kinase (MAPK)/Mnk signaling pathways. Recent studies have shown that Mnk-mediated eIF4E phosphorylation is absolutely required for eIF4E’s oncogenic function. Overexpression of eIF4E has been reported in many types of cancers; however, the expression of phosphorylated eIF4E (p-eIF4E) in human cancer tissues, particularly solid tumor tissues, has not been reported. The current study focused on evaluating p-eIF4E expression patterns in the tumor tissues obtained from patients with a variety of malignancies. Using three different tissue microarrays consisting of a total of 380 cases of human cancers and 146 cases of adjacent normal tissues, we detected p-eIF4E positive staining in 63.4% (241/380) of cancers, but only in 30.1% (44/146) of adjacent normal tissues. Thus, p-eIF4E expression is significantly higher in cancers than in adjacent normal tissues (P < 0.001). In general, there was no major difference in p-eIF4E staining between cancers with and without lymph node metastasis. In certain types of maligancies such as lung, gastric and colorectal cancers, p-eIF4E staining was significantly higher in the early stage (T1) than in the late stage (T3) disease (P < 0.05). Collectively, these findings suggest that p-eIF4E may play a critical role in cancer development, particularly early stages of tumorigenesis and support p-eIF4E as a good cancer therapeutic target.
PMCID: PMC2804981  PMID: 19483468
eIF4E; phosphorylation; cancer
6.  Cbl Negatively Regulates JNK Activation and Cell Death 
Cell research  2009;19(8):950-961.
Here, we explore the role of Cbl proteins in regulation of neuronal apoptosis. In two paradigms of neuron apoptosis – nerve growth factor (NGF) deprivation and DNA damage – cellular levels of c-Cbl and Cbl-b fell well before onset of death. NGF deprivation also induced rapid loss of tyrosine phosphorylation (and most likely, activation) of c-Cbl. Targeting c-Cbl and Cbl-b with siRNAs to mimic their loss/inactivation sensitized neuronal cells to death promoted by NGF deprivation or DNA damage. One potential mechanism by which Cbl proteins might affect neuron death is by regulation of apoptotic JNK signaling. We demonstrate that Cbl proteins interact with the JNK pathway components MLK3 and POSH and that knockdown of Cbl proteins is sufficient to increase JNK pathway activity. Furthermore, expression of c-Cbl blocks the ability of MLKs to signal to downstream components of the kinase cascade leading to JNK activation and protects neuronal cells from death induced by MLKs, but not from downstream JNK activators. On the basis of these findings, we propose that Cbls suppress cell death in healthy neurons at least in part by inhibiting the ability of MLKs to activate JNK signaling. Apoptotic stimuli lead to loss of Cbl protein/activity, thereby removing a critical brake on JNK activation and on cell death.
PMCID: PMC2739106  PMID: 19546888
Apoptosis; JNK; Cbl; MLK; NGF
7.  Mitochondrial DNA Mutation Stimulates Prostate Cancer Growth in Bone Stromal Environment 
The Prostate  2009;69(1):1-11.
Background and Objectives
Mitochondrial DNA (mtDNA) mutations, inherited and somatically acquired, are common in clinical prostate cancer. We have developed model systems designed to study specific mtDNA mutations in controlled experiments. Because prostate cancer frequently metastasizes to bone we tested the hypothesis that mtDNA mutations enhance prostate cancer growth and survival in the bone microenvironment.
The pathogenic nucleotide position (np) 8993 mDNA mutation was introduced into PC3 prostate cancer cells by cybrid formation. Wildtype and mutant cybrids were grown as nude mouse subcutaneous xenografts with or without bone stromal cell co-inoculation. Cybrids were also grown in the intratibial space. Tumor growth was assayed by direct tumor measurement and luciferase chemiluminescence. Gene expression was assayed using cDNA microarrays confirmed by real time PCR, western blot analysis and immunohistochemistry.
Cybrids with the 8993 mtDNA mutation grew faster than wildtype cybrids. Further growth acceleration was demonstrated in the bone microenvironment. A thirty-seven gene molecular signature characterized the growth advantage conferred by the mtDNA mutation and bone microenvironment. Two genes of known importance in clinical prostate cancer, FGF1 and FAK, were found to be substantially upregulated only when both mtDNA mutation and bone stromal cell were present.
The ATP6 np 8993 mtDNA mutation confers a growth advantage to human prostate cancer that is most fully manifest in the bone microenvironment. The identification of specific molecular alterations associated with mtDNA mutation and growth in bone may allow new understanding of prostate cancer bone metastasis.
PMCID: PMC2753601  PMID: 18850577
8.  Adenine Nucleotide Translocator Cooperates with Core Cell Death Machinery To Promote Apoptosis in Caenorhabditis elegans▿ ‡  
Molecular and Cellular Biology  2009;29(14):3881-3893.
In Caenorhabditis elegans, the central cell-killing process is essentially controlled by the interplay of four apoptotic factors: EGL-1/BH3-only protein, CED-9/Bcl2, CED-4/Apaf1, and CED-3/caspase. In cells destined to die, EGL-1 binds to CED-9 and results in the release of CED-4 from the mitochondrion-tethered CED-9-CED-4 complex to the perinucleus, which facilitates processing of the CED-3 caspase to cause apoptosis. However, whether additional factors exist to regulate the cell-killing process remains largely unknown. We have identified here WAN-1, the C. elegans ortholog of mammalian adenine nucleotide translocator, as an important cell death regulator. Genetic inactivation of wan-1 significantly suppressed both somatic and germ line cell deaths in C. elegans. Consistently, chemical inhibition of WAN-1 activity also caused strong reduction of germ line apoptosis. WAN-1 localizes to mitochondria and can form complex with both CED-4 and CED-9. Importantly, the cell death initiator EGL-1 can disrupt the interaction between CED-9 and WAN-1. In addition, overexpression of WAN-1 induced ectopic cell killing dependently on the core cell death pathway. These findings suggest that WAN-1 is involved in the central cell-killing process and cooperates with the core cell death machinery to promote programmed cell death in C. elegans.
PMCID: PMC2704750  PMID: 19414600
9.  Targeted Cancer Gene Therapy Using a Hypoxia Inducible Factor–Dependent Oncolytic Adenovirus Armed with Interleukin-4 
Cancer research  2007;67(14):6872-6881.
There is a need for novel therapies targeting hypoxic cells in tumors. These cells are associated with tumor resistance to therapy and express hypoxia inducible factor-1 (HIF-1), a transcription factor that mediates metabolic adaptation to hypoxia and activates tumor angiogenesis. We previously developed an oncolytic adenovirus (HYPR-Ad) for the specific killing of hypoxic/HIF-active tumor cells, which we now armed with an interleukin-4 gene (HYPR-Ad-IL4). We designed HYPR-Ad-IL4 by cloning the Ad E1A viral replication and IL-4 genes under the regulation of a bidirectional hypoxia/HIF-responsive promoter. The IL-4 cytokine was chosen for its ability to induce a strong host antitumor immune response and its potential antiangiogenic activity. HYPR-Ad-IL4 induced hypoxia-dependent IL-4 expression, viral replication, and conditional cytolysis of hypoxic, but not normoxic cells. The treatment of established human tumor xenografts with HYPR-Ad-IL4 resulted in rapid and maintained tumor regression with the same potency as that of wild-type dl309-Ad. HYPR-Ad-IL4–treated tumors displayed extensive necrosis, fibrosis, and widespread viral replication. Additionally, these tumors contained a distinctive leukocyte infiltrate and prominent hypoxia. The use of an oncolytic Ad that locally delivers IL-4 to tumors is novel, and we expect that HYPR-Ad-IL4 will have broad therapeutic use for all solid tumors that have hypoxia or active HIF, regardless of tissue origin or genetic alterations.
PMCID: PMC2262867  PMID: 17638898
10.  Regulation of Apoptotic c-Jun N-Terminal Kinase Signaling by a Stabilization-Based Feed-Forward Loop†  
Molecular and Cellular Biology  2005;25(22):9949-9959.
A sequential kinase cascade culminating in activation of c-Jun N-terminal kinases (JNKs) plays a fundamental role in promoting apoptotic death in many cellular contexts. The mechanisms by which this pathway is engaged in response to apoptotic stimuli and suppressed in viable cells are largely unknown. Here, we show that apoptotic stimuli increase endogenous cellular levels of pathway components, including POSH, mixed lineage kinases (MLKs), and JNK interacting protein 1, and that this effect occurs through protein stabilization and requires the presence of POSH as well as activation of MLKs and JNKs. Our findings suggest a self-amplifying, feed-forward loop mechanism by which apoptotic stimuli promote the stabilization of JNK pathway components, thereby contributing to cell death.
PMCID: PMC1280282  PMID: 16260609
11.  The MLK Family Mediates c-Jun N-Terminal Kinase Activation in Neuronal Apoptosis 
Molecular and Cellular Biology  2001;21(14):4713-4724.
Neuronal apoptotic death induced by nerve growth factor (NGF) deprivation is reported to be in part mediated through a pathway that includes Rac1 and Cdc42, mitogen-activated protein kinase kinases 4 and 7 (MKK4 and -7), c-Jun N-terminal kinases (JNKs), and c-Jun. However, additional components of the pathway remain to be defined. We show here that members of the mixed-lineage kinase (MLK) family (including MLK1, MLK2, MLK3, and dual leucine zipper kinase [DLK]) are expressed in neuronal cells and are likely to act between Rac1/Cdc42 and MKK4 and -7 in death signaling. Overexpression of MLKs effectively induces apoptotic death of cultured neuronal PC12 cells and sympathetic neurons, while expression of dominant-negative forms of MLKs suppresses death evoked by NGF deprivation or expression of activated forms of Rac1 and Cdc42. CEP-1347 (KT7515), which blocks neuronal death caused by NGF deprivation and a variety of additional apoptotic stimuli and which selectively inhibits the activities of MLKs, effectively protects neuronal PC12 cells from death induced by overexpression of MLK family members. In addition, NGF deprivation or UV irradiation leads to an increase in both level and phosphorylation of endogenous DLK. These observations support a role for MLKs in the neuronal death mechanism. With respect to ordering the death pathway, dominant-negative forms of MKK4 and -7 and c-Jun are protective against death induced by MLK overexpression, placing MLKs upstream of these kinases. Additional findings place the MLKs upstream of mitochondrial cytochrome c release and caspase activation.
PMCID: PMC87148  PMID: 11416147
12.  Epigenetic regulation of Atrophin1 by lysine-specific demethylase 1 is required for cortical progenitor maintenance 
Nature Communications  2014;5:5815.
Lysine-specific demethylase 1 (LSD1) is involved in gene regulation and development; however, its precise function, molecular targets and underlying mechanisms during development are poorly understood. Here we show that LSD1 is required for neuronal progenitor cell (NPC) maintenance during cortical development. A ChIP-seq analysis identified a LSD1-binding site (LBAL) downstream of Atrophin1 (ATN1). Surprisingly, tranylcypromine (LSD1 inhibitor) treatment increased H3K4 methylation at LBAL, leading to ATN1 repression and NPC differentiation. Knockdown of LSD1 and ATN1 phenocopied each other in inducing NPC premature differentiation and depletion, which could be rescued by ATN1 overexpression, suggesting that LSD1 controls NPC differentiation via regulation of ATN1 methylation status and expression. The involvement of LSD1 in ATN1 expression and NPC maintenance were confirmed in knockout mice. These findings hint at the potential application for the clinical drug, tranylcypromine, in the prevention and/or treatment of ATN1-associated degenerative disease, dentatorubral-pallidoluysian atrophy.
Histone modification is critical for gene expression regulation during development. Here, the authors show that the demethylase LSD1 and its target gene ATN1 are responsible for maintenance of neural progenitor cells during mouse cortical development.
PMCID: PMC4284801  PMID: 25519973

Results 1-12 (12)