Publications by authors named "Dazhong Xu"

40 Publications

Gene 33/Mig6/ERRFI1, an Adapter Protein with Complex Functions in Cell Biology and Human Diseases.

Authors:
Dazhong Xu Cen Li

Cells 2021 Jun 22;10(7). Epub 2021 Jun 22.

Department of Pathology, Microbiology and Immunology, New York Medical College School of Medicine, Valhalla, NY 10595, USA.

Gene 33 (also named Mig6, RALT, and ERRFI1) is an adapter/scaffold protein with a calculated molecular weight of about 50 kD. It contains multiple domains known to mediate protein-protein interaction, suggesting that it has the potential to interact with many cellular partners and have multiple cellular functions. The research over the last two decades has confirmed that it indeed regulates multiple cell signaling pathways and is involved in many pathophysiological processes. Gene 33 has long been viewed as an exclusively cytosolic protein. However, recent evidence suggests that it also has nuclear and chromatin-associated functions. These new findings highlight a significantly broader functional spectrum of this protein. In this review, we will discuss the function and regulation of Gene 33, as well as its association with human pathophysiological conditions in light of the recent research progress on this protein.
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http://dx.doi.org/10.3390/cells10071574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8306081PMC
June 2021

Regulation of the SIAH2-HIF-1 Axis by Protein Kinases and Its Implication in Cancer Therapy.

Authors:
Dazhong Xu Cen Li

Front Cell Dev Biol 2021 25;9:646687. Epub 2021 Mar 25.

Department of Pathology, Microbiology and Immunology, School of Medicine, New York Medical College, Valhalla, NY, United States.

The cellular response to hypoxia is a key biological process that facilitates adaptation of cells to oxygen deprivation (hypoxia). This process is critical for cancer cells to adapt to the hypoxic tumor microenvironment resulting from rapid tumor growth. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor and a master regulator of the cellular response to hypoxia. The activity of HIF-1 is dictated primarily by its alpha subunit (HIF-1α), whose level and/or activity are largely regulated by an oxygen-dependent and ubiquitin/proteasome-mediated process. Prolyl hydroxylases (PHDs) and the E3 ubiquitin ligase Von Hippel-Lindau factor (VHL) catalyze hydroxylation and subsequent ubiquitin-dependent degradation of HIF-1α by the proteasome. Seven Homolog 2 (SIAH2), a RING finger-containing E3 ubiquitin ligase, stabilizes HIF-1α by targeting PHDs for ubiquitin-mediated degradation by the proteasome. This SIAH2-HIF-1 signaling axis is important for maintaining the level of HIF-1α under both normoxic and hypoxic conditions. A number of protein kinases have been shown to phosphorylate SIAH2, thereby regulating its stability, activity, or substrate binding. In this review, we will discuss the regulation of the SIAH2-HIF-1 axis via phosphorylation of SIAH2 by these kinases and the potential implication of this regulation in cancer biology and cancer therapy.
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http://dx.doi.org/10.3389/fcell.2021.646687DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8027324PMC
March 2021

Downregulation of miR-200c stabilizes XIAP mRNA and contributes to invasion and lung metastasis of bladder cancer.

Cell Adh Migr 2019 12;13(1):236-248

a Nelson Institute of Environmental Medicine and Department of Environmental Medicine , New York University School of Medicine , Tuxedo , NY , USA.

Our previous studies have demonstrated that XIAP promotes bladder cancer metastasis through upregulating RhoGDIβ/MMP-2 pathway. However, the molecular mechanisms leading to the XIAP upregulation was unclear. In current studies, we found that XIAP was overexpressed in human high grade BCs, high metastatic human BCs, and in mouse invasive BCs. Mechanistic studies indicated that XIAP overexpression in the highly metastatic T24T cells was due to increased mRNA stability of XIAP that was mediated by downregulated miR-200c. Moreover, the downregulated miR-200c was due to CREB inactivation, while miR-200c downregulation reduced its binding to the 3'-UTR region of XIAP mRNA. Collectively, our results demonstrate the molecular basis leading to XIAP overexpression and its crucial role in BC invasion.
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http://dx.doi.org/10.1080/19336918.2019.1633851DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6601559PMC
December 2019

[Multifunctional Cervical Health Care Pillow].

Zhongguo Yi Liao Qi Xie Za Zhi 2018 Sep;42(5):341-344

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055.

Cervical spondylosis is due to degenerative cervical disc and its stimulation or oppression of the adjacent nerves, spinal cord, spinal artery and other tissue caused by clinical symptoms. The cervical spine is an anatomical structure with activity, while the pillow has a certain plastic fixation effect on the cervical spine anatomy. Therefore, the pillow not only plays a health role in the cervical spine, but also plays an important role in restoring the normal physiological curvature of the cervical spine. Based on this, a multi-functional cervical vertebra treatment pillow is designed, which not only has the functions of traction, maintaining different positions of the cervical spine, correcting the cervical curvature and equipment exercises, but also has the functions of voice broadcast and network data terminal.
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http://dx.doi.org/10.3969/j.issn.1671-7104.2018.05.009DOI Listing
September 2018

[Development of Software System for Artificial Joint Biomechanics].

Zhongguo Yi Liao Qi Xie Za Zhi 2018 Sep;42(5):330-331

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055.

In the research of artificial joint biomechanics, it is a common method in the world to evaluate the biomechanical properties of the implanted fixtures through experiments . The domestic research started late, and the corresponding testing software were lacking. There is still no special software. In this paper, an integrated software test system was designed and built based on the existing hardware system, including:hardware control, data collection, data save, data processing and display. It can directly show the 3D motion trajectory and the angle curve of joints. The system can accurately measure the relative motion angle value, external torque value, and inter pressure value of each joint. It has some reference significance for the development of the artificial joints' evaluation system.
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http://dx.doi.org/10.3969/j.issn.1671-7104.2018.05.005DOI Listing
September 2018

[Hardware System for the Test of Artificial Joint Biomechanics].

Zhongguo Yi Liao Qi Xie Za Zhi 2018 Jul;42(4):256-258

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055.

In the research of artificial joint biomechanics, it is a common method in the world to evaluate the biomechanical properties of the implanted fixtures through experiments . The domestic research started late, and the corresponding testing methods were lacking. There is still no unified standard. In this paper, a complete hardware test system was designed and built around the existing mechanical testing machine, including:binocular vision catcher, torque bearing clamp, film pressure sensor and so on. The system can accurately measure the relative motion angle value, external torque value, and inter pressure value of each joint. It has some reference significance for the forming and standardization of the artificial joints' evaluation system.
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http://dx.doi.org/10.3969/j.issn.1671-7104.2018.04.007DOI Listing
July 2018

Melatonin protects mouse spermatogonial stem cells against hexavalent chromium-induced apoptosis and epigenetic histone modification.

Toxicol Appl Pharmacol 2018 02 28;340:30-38. Epub 2017 Dec 28.

College of Animal Science and Technology, Northwest A&F University, Shaanxi 712100, China. Electronic address:

Given the potential biological functions of spermatogonial stem cells (SSCs) in spermatogenesis and in delivering parental genetic information to the next generation, how these cells respond to environmental toxins and carcinogens should be investigated. We examined the toxic effect of hexavalent chromium (Cr(VI)) on global histone modifications and apoptotic signaling pathways in SSCs. We determined the effect of melatonin, one of the most powerful endogenous free radical scavengers and wide-spectrum antioxidants, in protecting SSCs from Cr(VI)-induced apoptosis and global histone modification by Western blot analysis. In addition, we examined the in vivo effect of melatonin on Cr(VI)-induced histological changes of seminiferous tubules in mouse testes. We also evaluated the fertility of male mice by monitoring litter size following intraperitoneal injection of these chemicals. Our study demonstrated the Cr(VI)-induced global increases in H3K9me3 and H3K27me3 and activated the apoptotic signaling pathway. Pretreatment of SSCs with melatonin alleviated Cr(VI)-induced apoptosis and the global increase of H3K9me3. Exposure to melatonin also attenuated the Cr(VI)-induced increase of the abundance of histone methyltransferase ESET. Furthermore, exogenous administration of melatonin protected mice against Cr(VI)-induced changes in testicular histology and germ cell apoptosis, which helped maintain normal spermatogenesis and male fertility. Our study revealed a potential new therapeutic approach for male reproductive injury caused by Cr(VI).
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http://dx.doi.org/10.1016/j.taap.2017.12.017DOI Listing
February 2018

Transcription factors and stress response gene alterations in human keratinocytes following Solar Simulated Ultra Violet Radiation.

Sci Rep 2017 10 19;7(1):13622. Epub 2017 Oct 19.

New York University, Department of Environmental Medicine, Tuxedo, New York, United States of America.

Ultraviolet radiation (UVR) from sunlight is the major effector for skin aging and carcinogenesis. However, genes and pathways altered by solar-simulated UVR (ssUVR), a mixture of UVA and UVB, are not well characterized. Here we report global changes in gene expression as well as associated pathways and upstream transcription factors in human keratinocytes exposed to ssUVR. Human HaCaT keratinocytes were exposed to either a single dose or 5 repetitive doses of ssUVR. Comprehensive analyses of gene expression profiles as well as functional annotation were performed at 24 hours post irradiation. Our results revealed that ssUVR modulated genes with diverse cellular functions changed in a dose-dependent manner. Gene expression in cells exposed to a single dose of ssUVR differed significantly from those that underwent repetitive exposures. While single ssUVR caused a significant inhibition in genes involved in cell cycle progression, especially G2/M checkpoint and mitotic regulation, repetitive ssUVR led to extensive changes in genes related to cell signaling and metabolism. We have also identified a panel of ssUVR target genes that exhibited persistent changes in gene expression even at 1 week after irradiation. These results revealed a complex network of transcriptional regulators and pathways that orchestrate the cellular response to ssUVR.
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http://dx.doi.org/10.1038/s41598-017-13765-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648893PMC
October 2017

Polo-like kinase 3, hypoxic responses, and tumorigenesis.

Cell Cycle 2017 21;16(21):2032-2036. Epub 2017 Sep 21.

a Department of Pathology , New York Medical College School of Medicine , Valhalla , NY , USA.

The cellular hypoxic response contributes to cell transformation and tumor progression. Hypoxia-inducible factor 1 (HIF-1) is a key transcription factor that mediates transcription of genes whose products are essential for cellular adaptation to hypoxia. The activity of HIF-1 is largely regulated by the abundance of its alpha subunit (HIF-1α), which is primarily regulated by an oxygen-dependent and ubiquitin/proteasome-mediated degradation process. The HIF-1α protein level is also regulated by protein kinases through phosphorylation. Polo-like kinase 3 (Plk3) is a serine/threonine protein kinase with a tumor suppressive function. Plk3 phosphorylates and destabilizes HIF-1α. Plk3 also phosphorylates and stabilizes PTEN, a known regulator of HIF-1α stability via the PI3K pathway. Our latest study showed that the Plk3 protein is suppressed by hypoxia or nickel treatment via the ubiquitin/proteasome system. We discovered that Seven in Absentia Homologue 2 (SIAH2) is the E3 ubiquitin ligase of Plk3 and that Plk3 in turn destabilizes SIAH2. Given the role of SIAH2 in promoting stability of HIF-1α, our work reveals a novel mutual regulatory mechanism between Plk3 and SIAH2, which may function to fine-tune the cellular hypoxic response. Here we discuss the role of Plk3 in the hypoxic response and tumorigenesis in light of these latest findings.
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http://dx.doi.org/10.1080/15384101.2017.1373224DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731420PMC
August 2018

Nuclear Gene 33/Mig6 regulates the DNA damage response through an ATM serine/threonine kinase-dependent mechanism.

J Biol Chem 2017 10 25;292(40):16746-16759. Epub 2017 Aug 25.

From the Department of Pathology,

Gene 33 (Mig6, ERRFI1) is an adaptor protein with multiple cellular functions. We recently linked Gene 33 to the DNA damage response (DDR) induced by hexavalent chromium (Cr(VI)), but the molecular mechanism remains unknown. Here we show that ectopic expression of Gene 33 triggers DDR in an ATM serine/threonine kinase (ATM)-dependent fashion and through pathways dependent or not dependent on ABL proto-oncogene 1 non-receptor tyrosine kinase (c-Abl). We observed the clear presence of Gene 33 in the nucleus and chromatin fractions of the cell. We also found that the nuclear localization of Gene 33 is regulated by its 14-3-3-binding domain and that the chromatin localization of Gene 33 is partially dependent on its ErbB-binding domain. Our data further indicated that Gene 33 may regulate the targeting of c-Abl to chromatin. Moreover, we observed a clear association of Gene 33 with histone H2AX and that ectopic expression of Gene 33 promotes the interaction between ATM and histone H2AX without triggering DNA damage. In summary, our results reveal nuclear functions of Gene 33 that regulate DDR. The nuclear localization of Gene 33 also provides a spatial explanation of the previously reported regulation of apoptosis by Gene 33 via the c-Abl/p73 pathway. On the basis of these findings and our previous studies, we propose that Gene 33 is a proximal regulator of DDR that promotes DNA repair.
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http://dx.doi.org/10.1074/jbc.M117.803338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5633135PMC
October 2017

Single-cell RNA sequencing reveals an altered gene expression pattern as a result of CRISPR/cas9-mediated deletion of Gene 33/Mig6 and chronic exposure to hexavalent chromium in human lung epithelial cells.

Toxicol Appl Pharmacol 2017 09 5;330:30-39. Epub 2017 Jul 5.

Department of Pathology, School of Medicine, New York Medical College, Valhalla, NY 10595, United States. Electronic address:

Gene 33 (Mig6, ERRFI1) is an adaptor protein with multiple cellular functions. We recently reported that depletion of this protein promotes lung epithelial cell transformation induced by hexavalent chromium [Cr(VI)]. However, the early molecular events that mediate this process are not clear. In the present study, we used single-cell RNA sequencing to compare gene expression profiles between BEAS-2B lung epithelial cells chronically exposed to a sublethal dose of Cr(VI) with or without CRISPR/cas9-mediated deletion of Gene 33. Our data reveal 83 differentially expressed genes. The most notable changes are genes associated with cell adhesion, oxidative stresses, protein ubiquitination, epithelial-mesenchymal transition/metastasis, and WNT signaling. Up-regulation of some neuro-specific genes is also evident, particularly ubiquitin carboxyl-terminal hydrolase L1 (UCHL1), a deubiquitinase and potential biomarker for lung cancer. Gene 33 deletion and/or Cr(VI) exposure did not cause discernable changes in cell morphology. However, Gene 33 deletion led to a modest but significant reduction of cells in the G2/M phase of the cell cycle regardless of Cr(VI) exposure. Gene 33 deletion also significantly reduced cell proliferation. Interestingly, Cr(VI) exposure eliminated the difference in cell proliferation between the two genotypes. Gene 33 deletion also significantly elevated cell migration. Our data indicate that combined Gene 33 deletion and chronic Cr(VI) exposure produces a gene expression pattern and a phenotype resemble those of the transformed lung epithelial cells. Given the known association of UCHL1 with lung cancer, we propose that UCHL1 is an important player in the early stage of lung epithelial cell transformation and tumorigenesis.
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http://dx.doi.org/10.1016/j.taap.2017.07.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562372PMC
September 2017

Mutual regulation between Polo-like kinase 3 and SIAH2 E3 ubiquitin ligase defines a regulatory network that fine-tunes the cellular response to hypoxia and nickel.

J Biol Chem 2017 07 17;292(27):11431-11444. Epub 2017 May 17.

From the Department of Pathology, School of Medicine, New York Medical College, Valhalla, New York 10595 and

Elevated cellular response to hypoxia, which contributes to cell transformation and tumor progression, is a prominent feature of malignant cells in solid tumors. Polo-like kinase 3 (Plk3) is a serine/threonine protein kinase known to inhibit the cellular response to hypoxia and tumorigenesis. Nickel compounds are well-established human carcinogens that induce tumorigenesis partly through their hypoxia-mimicking effects. Despite previous research efforts, the role of Plk3 in the hypoxic response induced by hypoxia or nickel is not completely understood. Here, we show that NiCl (Ni(II)) or hypoxia reduces the protein level and shortens the half-life of cytoplasmic Plk3 in a ubiquitin-proteasome-dependent manner. We identify SIAH2, a RING finger E3 ubiquitin ligase associated with the cellular hypoxic response, to be the ubiquitin E3 ligase that mediates the degradation of Plk3. We show that SIAH2 binds to Plk3 and mediates its ubiquitination primarily through its polo-box domain. We report that USP28, a deubiquitinase known to be inhibitable by Ni(II) or hypoxia, may also contribute to the suppression of the Plk3 protein by Ni(II). We also show that Plk3 in turn suppresses the SIAH2 protein level in a kinase activity-dependent manner. Our study revealed an interesting mutual regulation between Plk3 and SIAH2 and uncovered a regulatory network that functions to fine-tune the cellular hypoxic response. We propose that suppression of Plk3 expression contributes to carcinogenesis and tumor progression induced by nickel compounds.
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http://dx.doi.org/10.1074/jbc.M116.767178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500808PMC
July 2017

Gene 33/Mig6 inhibits hexavalent chromium-induced DNA damage and cell transformation in human lung epithelial cells.

Oncotarget 2016 Feb;7(8):8916-30

Department of Pathology, School of Medicine, New York Medical College, Valhalla, NY, USA.

Hexavalent Chromium [Cr(VI)] compounds are human lung carcinogens and environmental/occupational hazards. The molecular mechanisms of Cr(VI) carcinogenesis appear to be complex and are poorly defined. In this study, we investigated the potential role of Gene 33 (ERRFI1, Mig6), a multifunctional adaptor protein, in Cr(VI)-mediated lung carcinogenesis. We show that the level of Gene 33 protein is suppressed by both acute and chronic Cr(VI) treatments in a dose- and time-dependent fashion in BEAS-2B lung epithelial cells. The inhibition also occurs in A549 lung bronchial carcinoma cells. Cr(VI) suppresses Gene 33 expression mainly through post-transcriptional mechanisms, although the mRNA level of gene 33 also tends to be lower upon Cr(VI) treatments. Cr(VI)-induced DNA damage appears primarily in the S phases of the cell cycle despite the high basal DNA damage signals at the G2M phase. Knockdown of Gene 33 with siRNA significantly elevates Cr(VI)-induced DNA damage in both BEAS-2B and A549 cells. Depletion of Gene 33 also promotes Cr(VI)-induced micronucleus (MN) formation and cell transformation in BEAS-2B cells. Our results reveal a novel function of Gene 33 in Cr(VI)-induced DNA damage and lung epithelial cell transformation. We propose that in addition to its role in the canonical EGFR signaling pathway and other signaling pathways, Gene 33 may also inhibit Cr(VI)-induced lung carcinogenesis by reducing DNA damage triggered by Cr(VI).
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http://dx.doi.org/10.18632/oncotarget.6866DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4891014PMC
February 2016

Expression of the p12 subunit of human DNA polymerase δ (Pol δ), CDK inhibitor p21(WAF1), Cdt1, cyclin A, PCNA and Ki-67 in relation to DNA replication in individual cells.

Cell Cycle 2014 ;13(22):3529-40

a Brander Cancer Research Institute; Department of Pathology; New York Medical College ; Valhalla , NY USA.

We recently reported that the p12 subunit of human DNA polymerase δ (Pol δ4) is degraded by CRL4(Cdt2) which regulates the licensing factor Cdt1 and p21(WAF1) during the G1 to S transition. Presently, we performed multiparameter laser scanning cytometric analyses of changes in levels of p12, Cdt1 and p21(WAF1), detected immunocytochemically in individual cells, vis-à-vis the initiation and completion of DNA replication. The latter was assessed by pulse-labeling A549 cells with the DNA precursor ethynyl-2'-deoxyribose (EdU). The loss of p12 preceded the initiation of DNA replication and essentially all cells incorporating EdU were p12 negative. Completion of DNA replication and transition to G2 phase coincided with the re-appearance and rapid rise of p12 levels. Similar to p12 a decline of p21(WAF1) and Cdt1 was seen at the end of G1 phase and all DNA replicating cells were p21(WAF1) and Cdt1 negative. The loss of p21(WAF1) preceded that of Cdt1 and p12 and the disappearance of the latter coincided with the onset of DNA replication. Loss of p12 leads to conversion of Pol δ4 to its trimeric form, Pol δ3, so that the results provide strong support to the notion that Pol δ3 is engaged in DNA replication during unperturbed progression through the S phase of cell cycle. Also assessed was a correlation between EdU incorporation, likely reflecting the rate of DNA replication in individual cells, and the level of expression of positive biomarkers of replication cyclin A, PCNA and Ki-67 in these cells. Of interest was the observation of stronger correlation between EdU incorporation and expression of PCNA (r = 0.73) than expression of cyclin A (r = 0.47) or Ki-67 (r = 0.47).
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http://dx.doi.org/10.4161/15384101.2014.958910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4614631PMC
September 2015

Arsenic induces polyadenylation of canonical histone mRNA by down-regulating stem-loop-binding protein gene expression.

J Biol Chem 2014 Nov 28;289(46):31751-31764. Epub 2014 Sep 28.

Department of Environmental Medicine, New York University School of Medicine, New York, New York 10016 and.

The replication-dependent histone genes are the only metazoan genes whose messenger RNA (mRNA) does not terminate with a poly(A) tail at the 3'-end. Instead, the histone mRNAs display a stem-loop structure at their 3'-end. Stem-loop-binding protein (SLBP) binds the stem-loop and regulates canonical histone mRNA metabolism. Here we report that exposure to arsenic, a carcinogenic metal, decreased cellular levels of SLBP by inducing its proteasomal degradation and inhibiting SLBP transcription via epigenetic mechanisms. Notably, arsenic exposure dramatically increased polyadenylation of canonical histone H3.1 mRNA possibly through down-regulation of SLBP expression. The polyadenylated H3.1 mRNA induced by arsenic was not susceptible to normal degradation that occurs at the end of S phase, resulting in continued presence into mitosis, increased total H3.1 mRNA, and increased H3 protein levels. Excess expression of canonical histones have been shown to increase sensitivity to DNA damage as well as increase the frequency of missing chromosomes and induce genomic instability. Thus, polyadenylation of canonical histone mRNA following arsenic exposure may contribute to arsenic-induced carcinogenesis.
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http://dx.doi.org/10.1074/jbc.M114.591883DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4231654PMC
November 2014

Intraluminal nonbacterial intestinal components control gut and lung injury after trauma hemorrhagic shock.

Ann Surg 2014 Dec;260(6):1112-20

From the Department of Surgery, UMDNJ-NJMS, Newark, NJ.

Objective: To test whether the mucus layer, luminal digestive enzymes, and intestinal mast cells are critical components in the pathogenesis of trauma shock-induced gut and lung injury.

Background: Gut origin sepsis studies have highlighted the importance of the systemic component (ischemia-reperfusion) of gut injury, whereas the intraluminal component is less well studied.

Methods: In rats subjected to trauma hemorrhagic shock (T/HS) or sham shock, the role of pancreatic enzymes in gut injury was tested by diversion of pancreatic enzymes via pancreatic duct exteriorization whereas the role of the mucus layer was tested via the enteral administration of a mucus surrogate. In addition, the role of mast cells was assessed by measuring mast cell activation and the ability of pharmacologic inhibition of mast cells to abrogate gut and lung injury. Gut and mucus injury was characterized functionally, morphologically, and chemically.

Results: Pancreatic duct exteriorization abrogated T/HS-induced gut barrier loss and limited chemical mucus changes. The mucus surrogate prevented T/HS-induced gut and lung injury. Finally, pancreatic enzyme-induced gut and lung injury seems to involve mast cell activation because T/HS activates mast cells and pharmacologic inhibition of intestinal mast cells prevented T/HS-induced gut and lung injury.

Conclusions: These results indicate that gut and gut-induced lung injury after T/HS involves a complex process consisting of intraluminal digestive enzymes, the unstirred mucus layer, and a systemic ischemic-reperfusion injury. This suggests the possibility of intraluminal therapeutic strategies.
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http://dx.doi.org/10.1097/SLA.0000000000000631DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4168009PMC
December 2014

Differential responses to genotoxic agents between induced pluripotent stem cells and tumor cell lines.

J Hematol Oncol 2013 Sep 20;6(1):71. Epub 2013 Sep 20.

College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.

Given potential values of induced pluripotent stem (iPS) cells in basic biomedical research and regenerative medicine, it is important to understand how these cells regulate their genome stability in response to environmental toxins and carcinogens. The present study characterized the effect of Cr(VI), a well-known genotoxic agent and environmental carcinogen, on major molecular components of DNA damage response pathways in human iPS cells. We compared the effect of Cr(VI) on human iPS cells with two established cell lines, Tera-1 (teratoma origin) and BEAS-2B (lung epithelial origin). We also studied the effect of hydrogen peroxide and doxorubicin on modulating DNA damage responses in these cell types. We demonstrated that ATM and p53 phosphorylation is differentially regulated in human iPS cells compared with Tera-1 and BEAS-2B cells after exposure to various genotoxic agents. Moreover, we observed that inhibition of CK2, but not p38, promotes phosphorylation of p53S392 in iPS cells. Combined, our data reveal some unique features of DNA damage responses in human iPS cells.
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http://dx.doi.org/10.1186/1756-8722-6-71DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856456PMC
September 2013

Enhancing bone marrow regeneration by SALL4 protein.

J Hematol Oncol 2013 Nov 5;6:84. Epub 2013 Nov 5.

Hematopoietic stem cells (HSCs) are widely used in transplantation therapy to treat a variety of blood diseases. The success of hematopoietic recovery is of high importance and closely related to the patient's morbidity and mortality after Hematopoietic stem cell transplantation (HSCT). We have previously shown that SALL4 is a potent stimulator for the expansion of human hematopoietic stem/progenitor cells in vitro. In these studies, we demonstrated that systemic administration with TAT-SALL4B resulted in expediting auto-reconstitution and inducing a 30-fold expansion of endogenous HSCs/HPCs in mice exposed to a high dose of irradiation. Most importantly, TAT-SALL4B treatment markedly prevented death in mice receiving lethal irradiation. Our studies also showed that TAT-SALL4B treatment was able to enhance both the short-term and long-term engraftment of human cord blood (CB) cells in NOD/SCID mice and the mechanism was likely related to the in vivo expansion of donor cells in a recipient. This robust expansion was required for the association of SALL4B with DNA methyltransferase complex, an epigenetic regulator critical in maintaining HSC pools and in normal lineage progression. Our results may provide a useful strategy to enhance hematopoietic recovery and reconstitution in cord blood transplantation with a recombinant TAT-SALL4B fusion protein.
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http://dx.doi.org/10.1186/1756-8722-6-84DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3882884PMC
November 2013

Nuclear protein IK undergoes dynamic subcellular translocation and forms unique nuclear bodies during the cell cycle.

Biomark Res 2013 Feb 18;1(1):11. Epub 2013 Feb 18.

Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, NY, 10987, USA.

IK is a nuclear protein containing a unique domain named RED due to the presence of a repetitive arginine (R), aspartic (E), and glutamic acid (D) sequence. To date, the function of this protein remains largely unknown despite of a couple of previous studies in the literature. Here we report that depletion of IK via RNA interference results in mitotic arrest. We also demonstrate that IK undergoes dynamic translocation during interphase and mitosis. In particular, IK is primarily present in some interphase cells as nuclear foci/bodies which do not co-localize with nucleoli, PMA bodies and Cajal bodies. Pull-down analysis coupled with mass spectrometry reveals that IK is associated with DHX15, a putative ATP-dependent RNA helicase. Our results strongly suggest that IK may participate in pre-mRNA splicing and that it may be a useful biomarker for a new nuclear structure in the cell.
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http://dx.doi.org/10.1186/2050-7771-1-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4177551PMC
February 2013

Parasympathetic stimulation via the vagus nerve prevents systemic organ dysfunction by abrogating gut injury and lymph toxicity in trauma and hemorrhagic shock.

Shock 2013 Jan;39(1):39-44

Department of General Surgery, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ, USA.

We tested if vagus nerve stimulation (VNS) would prevent gut injury, mesenteric lymph toxicity, and systemic multiple organ dysfunction syndrome following trauma-hemorrhagic shock (T/HS). Four groups of experiments were performed. The first tested whether VNS (5 V for 10 min) would protect against T/HS-induced increases in gut and lung permeability as well as neutrophil priming. In the second experiment, mesenteric lymph was collected from rats subjected to T/HS or trauma-sham shock with or without VNS and then injected into naive mice to assess its biologic activity. Lung permeability, neutrophil priming, and red blood cell deformability were measured. Next, the role of the spleen in VNS-mediated protection was tested by measuring gut and lung injury in splenectomized rats subjected to sham or actual VNS. Lastly, the ability of nicotine to replicate the gut-protective effect of VNS was tested. Vagus nerve stimulation protected against T/HS-induced gut injury, lung injury, and neutrophil priming (P < 0.05). Not only did VNS limit organ injury after T/HS, but in contrast to the mesenteric lymph collected from the sham-VNS T/HS rats, the mesenteric lymph from the VNS T/HS rats did not cause lung injury, neutrophil priming, or loss of red blood cell deformability (P < 0.05) when injected into naive mice. Removal of the spleen did not prevent the protective effects of VNS on gut or lung injury after T/HS. Similar to VNS, the administration of nicotine also protected the gut from injury after T/HS. Vagus nerve stimulation prevents T/HS-induced gut injury, lung injury, neutrophil priming, and the production of biologically active mesenteric lymph. This protective effect of VNS was not dependent on the spleen but appeared to involve a cholinergic nicotinic receptor, because its beneficial effects could be replicated with nicotine.
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http://dx.doi.org/10.1097/SHK.0b013e31827b450dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547655PMC
January 2013

Roles of Polo-like kinase 3 in suppressing tumor angiogenesis.

Exp Hematol Oncol 2012 Apr 18;1(1). Epub 2012 Apr 18.

Department of Environmental Medicine, New York University Langone Medical Center, 57 Old Forge Road, Tuxedo, NY 10987, USA.

Angiogenesis is essential for promoting growth and metastasis of solid tumors by ensuring blood supply to the tumor mass. Targeting angiogenesis is therefore an attractive approach to therapeutic intervention of cancer. Tumor angiogenesis is a process that is controlled by a complex network of molecular components including sensors, signaling transducers, and effectors, leading to cellular responses under hypoxic conditions. Positioned at the center of this network are the hypoxia-inducible factors (HIFs). HIF-1 is a major transcription factor that consists of two subunits, HIF-1α and HIF-1β. It mediates transcription of a spectrum of gene targets whose products are essential for mounting hypoxic responses. HIF-1α protein level is very low in the normoxic condition but is rapidly elevated under hypoxia. This dramatic change in the cellular HIF-1α level is primarily regulated through the proteosome-mediated degradation process. In the past few years, scientific progress has clearly demonstrated that HIF-1α phosphorylation is mediated by several families of protein kinases including GSK3β and ERKs both of which play crucial roles in the regulation of HIF-1α stability. Recent research progress has identified that Polo-like kinase 3 (Plk3) phosphorylates HIF-1α at two previously unidentified serine residues and that the Plk3-mediated phosphorylation of these residues results in destabilization of HIF-1α. Plk3 has also recently been found to phosphorylate and stabilize PTEN phosphatase, a known regulator of HIF-1α and tumor angiogenesis. Given the success of targeting protein kinases and tumor angiogenesis in anti-cancer therapies, Plk3 could be a potential molecular target for the development of novel and effective therapeutic agents for cancer treatment.
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http://dx.doi.org/10.1186/2162-3619-1-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3506990PMC
April 2012

Antagonistic effect of small-molecule inhibitors of Wnt/β-catenin in multiple myeloma.

Anticancer Res 2012 Nov;32(11):4697-707

New York University School of Medicine, Department of Environmental Medicine, Tuxedo, NY 10987, USA.

Background: Development and progression of multiple myeloma is dependent on the bone marrow (BM) microenvironment, and within the BM, a number of factors are secreted, including the Wnt ligands. Bone marrow stromal cells (BMSC) secrete Wnt ligands that activate Wnt signaling in multiple myeloma. The canonical Wnt pathway which is mediated through the transcriptional effector β-catenin (β-cat) is commonly de-regulated in many cancers. Cells with active β-cat-regulated transcription (CRT) are protected against apoptosis; conversely, inhibition of CRT may prevent cell proliferation.

Materials And Methods: In this study, we tested the efficacy of recently described inhibitors of CRT (iCRTs; oxazole and thiazole) for their selective antagonistic effect on Wnt-β-cat response in MM cells MM.1, U266, BMSC and primary BMMC obtained from patient samples (n=16).

Results: We demonstrated that iCRTs we used, block Wnt/β-cat reporter activity, down regulate β-cat expression and inhibit cell proliferation in a dose-dependent manner with an optimal dose closer to 15 μM. Our data further indicate that iCRTs do not influence the expression of the upstream components of the Wnt pathway DKK1 at the optimal dose, suggesting that iCRTs may specifically target β-cat in MM cells. Additionally, iCRT-treatment of MM cells, co-cultured with BMSC, showed an inhibitory effect on VEGF and cell migration.

Conclusion: This study provides the first in vitro data evaluation of newly-described iCRTs as potential Wnt-β-cat/VEGF pathway antagonists in multiple myeloma.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3983472PMC
November 2012

The function of mammalian Polo-like kinase 1 in microtubule nucleation.

Authors:
Dazhong Xu Wei Dai

Proc Natl Acad Sci U S A 2011 Jul 24;108(28):11301-2. Epub 2011 Jun 24.

Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987, USA.

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http://dx.doi.org/10.1073/pnas.1107723108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136282PMC
July 2011

Anticoagulants influence the in vitro activity and composition of shock lymph but not its in vivo activity.

Shock 2011 Aug;36(2):177-83

Department of Surgery, UMDNJ-New Jersey Medical School, Newark, NJ 07103, USA.

Many models of trauma-hemorrhagic shock (T/HS) involve the reinfusion of anticoagulated shed blood. Our recent observation that the anticoagulant heparin induces increased mesenteric lymph lipase activity and consequent in vitro endothelial cell cytotoxicity prompted us to investigate the effect of heparin-induced lipase activity on organ injury in vivo as well as the effects of other anticoagulants on mesenteric lymph bioactivity in vitro and in vivo. To investigate this issue, rats subjected to trauma-hemorrhage had their shed blood anticoagulated with heparin, the synthetic anticoagulant arixtra (fondaparinux sodium), or citrate. Arixtra, in contrast to heparin, did not increase lymph lipase activity or result in high levels of endothelial cytotoxicity. Yet, the arixtra-treated rats subjected to T/HS still manifested lung injury, neutrophil priming, and red blood cell dysfunction, which was totally abrogated by lymph duct ligation. Furthermore, the injection of T/HS mesenteric lymph, but not sham-shock lymph, collected from the arixtra rats into control mice recreated the pattern of lung injury, polymorphonucleocyte (PMN) priming, and red blood cell dysfunction observed after actual shock. Consistent with these observations, citrate-anticoagulated rats subjected to T/HS developed lung injury, and the injection of mesenteric lymph from the citrate-anticoagulated T/HS rats into control mice also resulted in lung injury. Based on these results, several conclusions can be drawn. First, heparin-induced increased mesenteric lymph lipase activity is not responsible for the in vivo effects of T/HS mesenteric lymph. Second, heparin should be avoided as an anticoagulant when studying the biology or composition of mesenteric lymph because of its ability to cause increases in lymph lipase activity that increase the in vitro cytotoxicity of these lymph samples.
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http://dx.doi.org/10.1097/SHK.0b013e3182205c30DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3261619PMC
August 2011

Regulation of PTEN stability and activity by Plk3.

J Biol Chem 2010 Dec 12;285(51):39935-42. Epub 2010 Oct 12.

Department of Environmental Medicine and Pharmacology, New York University School of Medicine, Tuxedo, New York 10987, USA.

By studying primary isogenic murine embryonic fibroblasts (MEFs), we have shown that PLK3 null MEFs contain a reduced level of phosphatase and tensin homolog (PTEN) and increased Akt1 activation coupled with decreased GSK3β activation under normoxia and hypoxia. Purified recombinant Plk3, but not a kinase-defective mutant, efficiently phosphorylates PTEN in vitro. Mass spectrometry identifies threonine 366 and serine 370 as two putative residues that are phosphorylated by Plk3. Immunoblotting using a phosphospecific antibody confirms these sites as Plk3 phosphorylation sites. Moreover, treatment of MEFs with LiCl, an inhibitor of GSK3β and CK2, only partially suppresses the phosphorylation, suggesting Plk3 as an additional kinase that phosphorylates these sites in vivo. Plk3-targeting mutants of PTEN are expressed at a reduced level in comparison with the wild-type counterpart, which is associated with an enhanced activity of PDK1, an upstream activator of Akt1. Furthermore, the reduced level of PTEN in PLK3 null MEFs is stabilized by treatment with MG132, a proteosome inhibitor. Combined, our study identifies Plk3 as a new player in the regulation of the PI3K/PDK1/Akt signaling axis by phosphorylation and stabilization of PTEN.
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http://dx.doi.org/10.1074/jbc.M110.166462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000975PMC
December 2010

Plk3 functions as an essential component of the hypoxia regulatory pathway by direct phosphorylation of HIF-1alpha.

J Biol Chem 2010 Dec 1;285(50):38944-50. Epub 2010 Oct 1.

Department of Environmental Medicine and Pharmacology, New York University School of Medicine, Tuxedo, New York 10987, USA.

Polo-like kinase 3 (Plk3) plays an important role in the regulation of cell cycle progression and stress responses. Plk3 also has a tumor-suppressing activity as aging PLK3-null mice develop tumors in multiple organs. The growth of highly vascularized tumors in PLK3-null mice suggests a role for Plk3 in angiogenesis and cellular responses to hypoxia. By studying primary isogenic murine embryonic fibroblasts, we tested the hypothesis that Plk3 functions as a component in the hypoxia signaling pathway. PLK3(-/-) murine embryonic fibroblasts contained an enhanced level of HIF-1α under hypoxic conditions. Immunoprecipitation and pulldown analyses revealed that Plk3 physically interacted with HIF-1α under hypoxia. Purified recombinant Plk3, but not a kinase-defective mutant, phosphorylated HIF-1α in vitro, resulting in a major mobility shift. Mass spectrometry identified two unique serine residues that were phosphorylated by Plk3. Moreover, ectopic expression followed by cycloheximide or pulse-chase treatment demonstrated that phospho-mutants exhibited a much longer half-life than the wild-type counterpart, strongly suggesting that Plk3 directly regulates HIF-1α stability in vivo. Combined, our study identifies Plk3 as a new and essential player in the regulation of the hypoxia signaling pathway.
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http://dx.doi.org/10.1074/jbc.M110.160325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2998109PMC
December 2010

The mucus layer is critical in protecting against ischemia-reperfusion-mediated gut injury and in the restitution of gut barrier function.

Shock 2011 Mar;35(3):275-81

Department of Surgery, University of Medicine and Dentistry, New Jersey-New Jersey Medical School, Newark, NJ 07103, USA.

It is well documented that the gut injury plays a critical role in the development of systemic inflammation and distant organ injury in conditions associated with splanchnic ischemia. Consequently, understanding the mechanisms leading to gut injury is important. In this context, recent work suggests a protective role for the intestinal mucus layer and an injury-inducing role for luminal pancreatic proteases. Thus, we explored the role of the mucus layer in gut barrier function by observing how the removal of the mucus layer affects ischemia-reperfusion-mediated gut injury in rats as well as the potential role of luminal pancreatic proteases in the pathogenesis of gut injury. Ischemia was induced by the ligation of blood vessels to segments of the ileum for 45 min, followed by up to 3 h of reperfusion. The ileal segments were divided into five groups. These included a nonischemic control, ischemic segments exposed to saline, the mucolytic N-acetylcysteine (NAC), pancreatic proteases, or NAC + pancreatic proteases. Changes in gut barrier function were assessed by the permeation of fluorescein isothiocyanate dextran (molecular weight, 4,000 d) in ileal everted sacs. Gut injury was measured morphologically and by the luminal content of protein, DNA, and hemoglobin. The mucus layer was assessed functionally by measuring its hydrophobicity and morphologically. Gut barrier function was promptly and effectively reestablished during reperfusion, which was accompanied by the restoration of the mucus layer. In contrast, treatment of the gut with the mucolytic NAC for 10 min during ischemia resulted in a failure of mucus restitution and further increases in gut permeability and injury. The presence of digestive proteases by themselves did not exacerbate gut injury, but in combination with NAC, they caused an even greater increase in gut injury and permeability. These results suggest that the mucus layer not only serves as a barrier between the luminal contents and gut surface epithelia, but also plays a critical role in the maintenance and restitution of gut barrier function.
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http://dx.doi.org/10.1097/SHK.0b013e3181f6aaf1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3261620PMC
March 2011

Covalent modifications of histones during mitosis and meiosis.

Cell Cycle 2009 Nov 24;8(22):3688-94. Epub 2009 Nov 24.

Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, NY, USA.

Higher order chromosome structures are the hallmark of mitotic and meiotic cells. Chromatin condensation and compaction are essential for rapid chromosome congression and accurate chromosome segregation during cell division. The core histones possess tails at their amino-termini. These tails, which extend from the surface of the nucleosomes, are highly dynamic and subject to an extensive array of covalent modifications. Modified histone tails play an important role, not only in the folding of nucleosomal arrays into higher order chromatin structures but also in gene regulation. The combination of these distinct covalent modifications of histones constitutes "the histone code" that regulates various cellular processes, including mitotic and meiotic progression.
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http://dx.doi.org/10.4161/cc.8.22.9908DOI Listing
November 2009

Molecular signatures of trauma-hemorrhagic shock-induced lung injury: hemorrhage- and injury-associated genes.

Shock 2007 Sep;28(3):360-8

Department of Surgery, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103, USA.

The etiology of trauma-hemorrhagic shock (T/HS)-induced acute lung injury has been difficult to elucidate because of, at least in part, the inability of in vivo studies to separate the noninjurious pulmonary effects of trauma-hemorrhage from the tissue-injurious ones. To circumvent this in vivo limitation, we used a model of T/HS in which T/HS lung injury was abrogated by dividing the mesenteric lymph duct. In this way, it was possible to separate the pulmonary injurious response from the noninjurious systemic response to T/HS by comparing the pulmonary molecular responses of rats subjected to T/HS, which did and did not develop lung injury, with those of nonshocked rats. Using high-density oligonucleotide arrays and treatment group comparisons of whole lung tissue collected at 3 h after the end of the shock or sham-shock period, 139 of 8,799 assessed genes were identified by significant analysis of microarrays. Hemorrhage without the secondary effects of lung injury modulated the expression of 21 genes such as interleukin 1beta, metallothionein-2, and myeloctomatosis oncogene (c-myc). In response to injury, 42 genes were identified to be differentially expressed. Upregulated genes included the L1 retroposon and guanine deaminase, whereas downregulated genes included catalase and superoxide dismutase 1. Real-time polymerase chain reaction confirmed the differential expression for selected genes. PathwayAssist analysis identified interleukin 1beta as a central regulator of two subpathways of stress response-related genes (c-myc and superoxide dismutase 1/catalase) as well as several unrelated genes such as lipoprotein lipase. Our model system provided a unique opportunity to distinguish the molecular changes associated with T/HS-induced acute lung injury from the systemic molecular response to T/HS.
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http://dx.doi.org/10.1097/shk.0b013e318048565bDOI Listing
September 2007

Gene 33/RALT is induced by hypoxia in cardiomyocytes, where it promotes cell death by suppressing phosphatidylinositol 3-kinase and extracellular signal-regulated kinase survival signaling.

Mol Cell Biol 2006 Jul;26(13):5043-54

Molecular Cardiology Research Institute, Tufts-New England Medical Center, 750 Washington Street, Box 8486, Boston, MA 02111, USA.

Ischemia in the heart deprives cardiomyocytes of oxygen, triggering cell death (myocardial infarction). Ischemia and its cell culture model, hypoxia, elicit a stress response program that contributes to cardiomyocyte death; however, the molecular components required to promote this process remain nebulous. Gene 33 is a 50-kDa cytosolic adapter protein that suppresses signaling from receptor Tyr kinases of the epidermal growth factor receptor/ErbB family. Here we show that adenoviral expression of Gene 33 swiftly stimulates cardiomyocyte death coincident with reduced Akt and extracellular signal-regulated kinase (ERK) signaling. Subjecting cardiomyocytes to hypoxia and then reoxygenation induces gene 33 mRNA and Gene 33 protein. RNA interference experiments indicate that endogenous Gene 33 reduces Akt and ERK signaling and is required for maximal hypoxia-induced cardiomyocyte death. Gene 33 levels are also strikingly increased in myocardial ischemic injury and infarction. Our results identify a new role for Gene 33 as a component in the molecular pathophysiology of ischemic injury.
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http://dx.doi.org/10.1128/MCB.02387-05DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1489166PMC
July 2006
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