bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paradoxical enhancement of oxidative cell injury by overexpression of heme oxygenase‐1 in an anchorage‐dependent cell ECV304
Authors: Maruhashi Keiko , Kasahara Yoshihito , Ohta Kunio , Wada Taizo , Ohta Kazuhide , Nakamura Nami , Toma Tomoko , Koizumi Shoichi , Yachie Akihiro 
Published: August 2004

AbstractThere has been increasing evidence suggesting the potent anti‐inflammatory roles of heme oxygenase‐1 (HO‐1) in protecting renal tubular epithelial cells, vascular endothelial cells, and circulating monocytes. Based on these findings, novel therapeutic interventions have been proposed to control the expression of endothelial HO‐1 levels to ameliorate various vascular diseases. We evaluated the effect of HO‐1 gene transfer into an anchorage‐dependent cell, ECV304. Effect of HO‐1 production on the cell injury induced by hydrogen peroxide was evaluated after hemin stimulation and after HO‐1 gene transfection. Morphological changes and the induction of various anti‐apoptotic proteins were examined at the same time. Levels of HO‐1 expression were variable in different clones of HO‐1‐transfected ECV304 cells. Among these, the clones with moderate levels of HO‐1 expression were significantly more resistant to oxidative stress. In contrast, those with the highest levels of HO‐1 exhibited paradoxically enhanced susceptibility to oxidative injury. Interestingly, the cell survival after oxidative stress was in parallel with the levels of Bcl‐2 expression and of fibronectin receptor, α5 integrin. It is suggested from these results, that excessive HO‐1 not only leads to enhanced cell injury, but also prolongs the repair process of the injured endothelial tissue. However, HO‐1 reduces the oxidative cell injury and protects the endothelial cells, if its expression is appropriately controlled. © 2004 Wiley‐Liss, Inc.
In vivo activated caspase‐3 cleaves PARP‐1 in rat liver after administration of the hepatocarcinogen N‐nitrosomorpholine (NNM) generating the 85 kDa fragment
Authors: Węsierska‐Gądek Józefa , Gueorguieva Marieta , Wojciechowski Jacek , Tudzarova‐Trajkovska Slavica 
Published: August 2004

AbstractWe reported previously that treatment of rats with the hepatocarcinogen N‐nitrosomorpholine (NNM) caused severe hepatotoxicity associated with apoptosis of hepatocytes beginning 12 h after administration of NNM. We observed that poly(ADP‐ribose) polymerase 1 (PARP‐1), one of the major nuclear targets for caspases, was proteolytically degraded generating primarily 64 and 54 kDa fragments. Interestingly, at 20, 30, and 40 h post‐treatment a 85 kDa cleavage product of PARP‐1 resembling that generated by caspase‐3 appeared additionally in hepatocytes. More detailed analysis performed in the present study revealed that the 85 kDa fragment of PARP‐1 was generated in the liver in 10 of 17 (60%) animals examined between 20 and 40 h after NNM administration. The caspase‐3 generated 85 kDa fragment was detected solely in hepatocytes undergoing apoptosis as evidenced by immunostaining performed with the antibody recognizing exclusively PARP‐1 cleaved at position 214/215. The appearance of the 85 kDa fragment of PARP‐1 in the liver nuclei coincided temporally with an significant increase of caspase‐3 activity in hepatocytes. In contrast, in testis samples obtained from the same animals, no changes characteristic for apoptosis such as induction of caspases activity or degradation of nuclear PARP‐1 could be detected. Our results evidence unequivocally that PARP‐1 in liver is not resistant to caspases and can be processed in vivo by activated caspase‐3 producing the p85 kDa fragment. Moreover, the caspase‐3 induced PARP‐1 fragmentation coinciding with the increase of caspase‐3 activity was detected solely in the target organ and exclusively in hepatocytes undergoing apoptosis. Considering the fact that the caspase‐3 mediated PARP‐1 cleavage occurred only in 60% of animals tested between 20 and 40 h, it becomes obvious that the cellular response in vivo to the same trigger(s) strongly varies and may depend on a variety of intrinsic factors. It remains to elucidate which additional factors may be involved in the modulation of cellular response to the strong insults thereby activating different pathways and generating distinct outcomes. © 2004 Wiley‐Liss, Inc.
The tyrosine phosphatase, OST‐PTP, is expressed in mesenchymal progenitor cells early during skeletogenesis in the mouse
Authors: Yunker Laurie A. , Undersander Anne , Lian Jane B. , Stein Gary S. , Carlson Cathy S. , Mauro Laura J. 
Published: August 2004

AbstractOsteotesticular protein tyrosine phosphatase (OST‐PTP; OST), is a signaling molecule which catalyzes the removal of phosphates from tyrosine residues. It is known to be highly regulated in bone cells and has been shown to be important for the in vitro progression from a preosteoblast to a mature, mineralizing cell. However, the in vivo expression of this phosphatase during skeletogenesis has not been examined. Using Northern analysis and in situ hybridization (ISH), we have observed that this gene is strongly expressed early during the formation of the mouse skeleton. By 12.5 days post‐coitum (dpc), expression of OST mRNA transcripts increases and is localized within the mesenchyme of craniofacial bones, ribs, limbs, and Meckel's cartilage. Following initiation of chondrogenesis, OST mRNA becomes restricted to the perichondrium of all endochondral elements. With ossification, this gene is also expressed by cells, presumably osteoblasts, at the chondro‐osseous border and along cortical and trabecular bone surfaces. Unlike other bone markers examined such as Osterix and type II collagen, OST transcripts do not appear to be expressed by chondrocytes of epiphyseal cartilage or by non‐hypertrophic or hypertrophic chondrocytes. Because the temporal expression patterns of OST and Runx2 were similar suggesting a potential interrelationship in bone regulation and function, OST expression was examined in transgenic mice lacking a functional Runx2/Cbfa1 protein (Runx2/Cbfa1 delta C (ΔC)) and possessing a cartilaginous skeleton. Interestingly, the OST gene was expressed with localization similar in wild‐type, homozygous, and heterozygous embryos. These studies suggest that the expression of the OST gene may be important during skeletogenesis, potentially from commitment of mesenchymal cells to the ossification of new bones. Early in embryogenesis, regulation of OST expression may be independent of Runx2/Cbfa1. © 2004 Wiley‐Liss, Inc.
The role of stathmin in the regulation of the cell cycle
Authors: Rubin Camelia Iancu , Atweh George F. 
Published: August 2004

AbstractStathmin is the founding member of a family of proteins that play critically important roles in the regulation of the microtubule cytoskeleton. Stathmin regulates microtubule dynamics by promoting depolymerization of microtubules and/or preventing polymerization of tubulin heterodimers. Upon entry into mitosis, microtubules polymerize to form the mitotic spindle, a cellular structure that is essential for accurate chromosome segregation and cell division. The microtubule‐depolymerizing activity of stathmin is switched off at the onset of mitosis by phosphorylation to allow microtubule polymerization and assembly of the mitotic spindle. Phosphorylated stathmin has to be reactivated by dephosphorylation before cells exit mitosis and enter a new interphase. Interfering with stathmin function by forced expression or inhibition of expression results in reduced cellular proliferation and accumulation of cells in the G2/M phases of the cell cycle. Forced expression of stathmin leads to abnormalities in or a total lack of mitotic spindle assembly and arrest of cells in the early stages of mitosis. On the other hand, inhibition of stathmin expression leads to accumulation of cells in the G2/M phases and is associated with severe mitotic spindle abnormalities and difficulty in the exit from mitosis. Thus, stathmin is critically important not only for the formation of a normal mitotic spindle upon entry into mitosis but also for the regulation of the function of the mitotic spindle in the later stages of mitosis and for the timely exit from mitosis. In this review, we summarize the early studies that led to the identification of the important mitotic function of stathmin and discuss the present understanding of its role in the regulation of microtubules dynamics during cell‐cycle progression. We also describe briefly other less mature avenues of investigation which suggest that stathmin may participate in other important biological functions and speculate about the future directions that research in this rapidly developing field may take. © 2004 Wiley‐Liss, Inc.
C‐terminal deletion mutant of MRE‐binding transcription factor‐1 inhibits MRE‐driven gene expression
Authors: Kimura Tomoki , Itoh Norio , Sone Tomomichi , Tanaka Keiichi , Isobe Masakazu 
Published: August 2004

AbstractHeavy metal‐induced transcriptional activation of the genes coding for metallothionein (MT) is mediated by a cis‐acting DNA element, the metal‐responsive element (MRE). MRE‐binding transcription factor‐1 (MTF‐1) is a highly conserved heavy metal‐induced transcriptional activator. MTF‐1 also activates transcription in response to oxidative stress and regulates the expression of several cytoprotective factor genes, including MT, γ‐glutamylcysteine synthetase, and Cu/Zn‐superoxide dismutase. It is thus thought that MTF‐1 plays a role in cellular stress response. The physiological role of MTF‐1 remains unclear because of the lack of MTF‐1‐specific activators and/or inhibitors. To obtain an MTF‐1‐specific inhibitor, we constructed an MTFΔC (amino acids 1–317), a C‐terminal deletion mutant of MTF‐1. MTFΔC could bind MRE and competed with MTF‐1 for MTF–MRE complex formation. Transient expression of MTFΔC in HepG2 cells reduced MRE‐driven gene expression, demonstrating that MTFΔC is dominant to MTF‐1. HepG2 cells stably expressing MTFΔC showed increased susceptibility to the cytotoxic effects of tert‐butyl hydroperoxide (tBH). Furthermore, we constructed Ad5MTFΔC, a recombinant adenovirus that expresses MTFΔC. Infection with the virus induced MTFΔC expression and increased susceptibility to the cytotoxic effects of tBH. These results indicate that MTF‐1 participates in controlling the cellular redox state. © 2004 Wiley‐Liss, Inc.
Overexpression of regucalcin suppresses cell death and apoptosis in cloned rat hepatoma H4‐II‐E cells induced by lipopolysaccharide, PD 98059, dibucaine, or Bay K 8644
Authors: Izumi Takako , Yamaguchi Masayoshi 
Published: August 2004

AbstractThe effect of regucalcin, a regulatory protein in intracellular signaling pathway, on cell death was investigated by using the cloned rat hepatoma H4‐II‐E cells overexpressing regucalcin. The hepatoma cells (wild‐type) and stable regucalcin (RC)/pCXN2 transfectants were cultured for 72 h in medium containing 10% fetal bovine serum (FBS) to obtain subconfluent monolayers. After culture for 72 h, cells were further cultured for 12–72 h in medium without FBS containing either vehicle or lipopolysaccharide (LPS; 0.1 or 1.0 μg/ml). The number of wild‐type cells was significantly decreased by culture for 24 or 48 h in the presence of LPS (0.1 or 1.0 μg/ml). The effect of LPS (0.1 or 1.0 μg/ml) in decreasing the number of hepatoma cells was significantly prevented in transfectants overexpressing regucalcin. However, the culture with LPS (0.1 or 1.0 μg/ml) for 72 h caused a significant decrease in cell number of transfectants. Ca2+/calmodulin‐dependent nitric oxide (NO) synthase activity was significantly decreased by culture with LPS (1.0 μg/ml) for 24–72 h of wild‐type cells. This decrease was significantly prevented in transfectants. LPS (0.1 or 1.0 μg/ml)‐induced decrease in the number of wild‐type cells was significantly prevented by culture with caspase‐3 inhibitor (10−8 M). Moreover, the number of wild‐type cells was significantly decreased by culture with PD 98059 (10−6 M), dibucaine (10−6 M), or staurosporine (10−6 M), which is an inhibitor of various protein kinases. The effect of PD 98059 or dibucaine on the number of wild‐type cells was not observed in transfectants, although the effect of staurosporine was seen in transfectants. Culture with Bay K 8644 (2.5 × 10−6 M), an agonist of Ca2+ entry in cells, caused a significant decrease in the number of wild‐type cells. Such an effect was not seen in transfectants. The presence of LPS did not significantly decrease the number of wild‐type cells in the presence of Bay K 8644. Agarose gel electrophoresis showed the presence of low‐molecular‐weight deoxyribonucleic acid (DNA) fragments of adherent wild‐type cells cultured with Bay K 8644, and this DNA fragmentation was significantly prevented in transfectants. This study demonstrates that overexpression of regucalcin has a suppressive effect on cell death induced by LPS or various intracellular signaling‐related factors. © 2004 Wiley‐Liss, Inc.
Apoptotic effect of PP2 a Src tyrosine kinase inhibitor, in murine B cell leukemia
Authors: Lee Michael , Kim Ji‐Young , Koh Woo Suk 
Published: August 2004

AbstractSrc is a non‐receptor protein tyrosine kinase that transduces signals regulating cell growth and differentiation. We report here that activation of signaling pathway after blockade of tyrosine phosphorylation by PP2 (4‐amino‐5‐(4‐chloro‐phenyl)‐7‐(t‐butyl)pyrazolo[3,4‐d]pyrimidine), a potent and selective inhibitor of the Src‐family tyrosine kinase, can lead to cell death in murine B cell leukemia, 70Z/3. Death from PP2 occurred by apoptosis as indicated by the induction of caspase activation and annexin V/propidium iodide staining. Interestingly, PP2 was found to be able to enhance the DNA binding activity of nuclear factor κB (NF‐κB) before induction of apoptosis without accompanying by increased phosphorylation of inhibitor of NF‐κB‐α (IκB‐α). Additionally, immunoblotting analysis with PP2‐treated cell extract demonstrated that, compared to other protein kinase C (PKC) isotypes, the translocation of novel PKC isotypes from the cytosol to membrane fraction was sustained for a longer time. These data suggest that the inhibition of Src‐mediated tyrosine phosphorylation by PP2 may tilt the balance between each PKC isotypes, which in turn, activate NF‐κB transcription factor, leading to apoptosis. © 2004 Wiley‐Liss, Inc.
Taming psoriatic keratinocytes—PTHs' uses go up another notch
Authors: Whitfield James F. 
Published: August 2004

AbstractThe native parathyroid hormone (PTH) and several of its N‐terminal adenylyl cyclase‐activating fragments and their analogs have become the star stimulators of bone growth for treating osteoporosis, accelerating fracture healing, and strengthening the anchorage of prosthetic bone implants and one of them (Lilly's Forteo™—recombinant hPTH‐(1‐34) has recently arrived in the clinic. But something entirely different has been lurking in the background—the ability of the adenylyl cyclase stimulating hPTH‐(1‐34) to calm hyperproliferating keratinocytes and reduce psoriatic lesions. By contrast PTH‐(7‐34) which cannot stimulate adenylyl cyclase actually stimulates keratinocyte proliferation. Normal keratinocytes make PTHrP after they lift off the basal lamina and have stopped cycling. But they have an unconventional PTH/PTHrP receptorr which is not coupled to adenylyl cyclase. Psoriatic keratinocytes do not make PTHrP and have only a broken‐down, proliferation‐limiting terminal differentiation‐driving Notch–Notch ligand mechanism. Putting these and other facts together produces a possible picture of an exogenously applied adenylyl cyclase‐activating PTH pinch hitting for the missing PTHrP and restoring normal keratinocyte proliferative activity epidermal structure by stimulating dermal fibroblasts which do have the conventional adenylyl cyclasse‐linked PTHR1 and in response directly or indirectly restore the overlying basal keratinocytes' Notch–Notch ligand terminal differentiation‐driving mechanism and consequently a normal epidermal structure. © 2004 Wiley‐Liss, Inc.
Elevated expression of the estrogen receptor prevents the down‐regulation of p21Waf1/Cip1 in hormone dependent breast cancer cells
Authors: Zhao Helen , Yu Jenny , Peltier Cheryl P. , Davie James R. 
Published: August 2004

AbstractExpression of an estrogen receptor α (ER) transgene in hormone independent breast cancer and normal breast epithelial cells arrests cell cycling when estradiol is added. Although endogenously expressed ER does not typically affect estradiol‐induced cell cycling of hormone dependent breast cancer cells, we observed that elevated expression of a green fluorescent protein fused to ER (GFP‐ER) hindered entry of estrogen treated MCF‐7 cells into S phase of the cell cycle. In analyses of key cell‐cycle regulating proteins, we observed that GFP‐ER expression had no affect on the protein levels of cyclin D1, cyclin E, or p27, a cyclin dependent kinase (Cdk) inhibitor. However, at 24 h, p21 (Waf1, Cip1; a Cdk2 inhibitor) protein remained elevated in the high GFP‐ER expressing cells but not in non‐GFP‐ER expressing cells. Elevated expression of p21 inhibited Cdk2 activity, preventing cells from entering S phase. The results show that elevated levels of ER prevented the down‐regulation of p21 protein expression, which is required for hormone responsive cells to enter S phase. © 2004 Wiley‐Liss, Inc.
New molecular markers of early and progressive CJD brain infection
Authors: Lu Zhi Yun , Baker Christopher A. , Manuelidis Laura 
Published: August 2004

AbstractTransmissible spongiform encephalopathies (TSEs), including human Creutzfeldt–Jakob disease (CJD), are caused by a related group of infectious agents that can be transmitted to many mammalian species. Because the infectious component of TSE agents has not been identified, we examined myeloid cell linked inflammatory pathways to find if they were activated early in CJD infection. We here identify a specific set of transcripts in CJD infected mouse brains that define early and later stages of progressive disease. Serum amyloid A3 and L‐selectin mRNAs were elevated as early as 20 days after intracerebral inoculation. Transcripts of myeloid cell recruitment factors such as MIP‐1α, MIP‐1β, and MCP1, as well as IL1α and TNFα were upregulated >10 fold between 30 and 40 days, well before prion protein (PrP) abnormalities that begin only after 80 days. At later stages of symptomatic neurodegenerative disease (100–110 days), a selected set of transcripts rose by as much as 100 fold. In contrast, normal brain inoculated controls showed no similar sequential changes. In sum, rapid and simple PCR tests defined progressive stages of CJD brain infection. These markers may also facilitate early diagnosis of CJD in accessible peripheral tissues such as spleen and blood. Because some TSE strains can differentially target particular cell types such as microglia, several of these molecular changes may also distinguish specific agent strains. The many host responses to the CJD agent challenge the assumption that the immune system does not recognize TSE infections because these agents are composed only of the host's own PrP. © 2004 Wiley‐Liss, Inc.
Proteomic analyzes of copper metabolism in an in vitro model of Wilson disease using surface enhanced laser desorption/ionization‐time of flight‐mass spectrometry
Authors: Roelofsen Han , Balgobind Reshma , Vonk Roel J. 
Published: August 2004

AbstractIn Wilson disease, mutations in theATP7B‐gene lead to hepatic accumulation of copper that becomes toxic when the hepatic binding capacity is exceeded, leading to oxidative stress and acute liver failure. Several proteins are probably involved in dealing with the excess copper and oxidative stress. As a first step towards biomarker discovery and analyzes of copper metabolism in Wilson disease patients we characterized copper‐induced changes in protein expression in cell lysates and culture media from an in vitro copper‐overload model using surface enhanced laser desorption/ionization (SELDI) proteomics technology. HepG2 cells were cultured for 48 h with a physiological (0.5 μM) or a pathological (100 μM) copper concentration. Samples were applied to weak cation exchange (WCX) proteinchip® arrays and chips were analyzed by time of flight (TOF)‐mass spectrometry. Copper‐coated IMAC chips were used to detect copper‐binding proteins in cell lysate of copper depleted cells using buffers with increasing imidazole concentrations. Data from the 2 to 50 kDa range indicate that high extra‐cellular copper substantially altered both intra‐cellular protein expression as well as the composition of the secretome. In the lysate 15 proteins were found up‐regulated, while 6 proteins were down‐regulated. In culture media 21 proteins were increased while 4 proteins were decreased in abundance. Copper‐coated protein chips revealed the presence of 18 high‐affinity copper‐binding proteins. Further identification is necessary to determine the exact cellular roles of the discovered proteins. © 2004 Wiley‐Liss, Inc.
Prostate specific antigen gene regulation by androgen receptor
Authors: Kim Joshua , Coetzee Gerhard A. 
Published: August 2004

AbstractProstate specific antigen (PSA) is a serine protease that is synthesized by both normal and malignant epithelial cells of the human prostate. PSA expressed by malignant cells, however, are released into the serum at an increased level, which can be detected to diagnose and monitor prostate cancer. Moreover, increases in serum PSA following local and systemic treatments are highly correlated with tumor recurrence and progression, and this association has further established PSA as a clinically important biomarker. The expression of PSA is mainly induced by androgens and regulated by the androgen receptor (AR) at the transcriptional level. Extensive research on the regulation of PSA gene expression has provided significant information about the function of AR, which is a crucial transcription factor involved in all phases of prostate cancer. Still, the molecular mechanism(s) by which the transcription of the PSA gene escapes regulation in advanced prostate cancer has yet to be clearly defined. Accumulating evidence suggests that a number of processes including androgen‐independent activation of AR are involved. Lacking an effective treatment, advanced prostate cancer is almost invariably fatal, which highlights the importance of elucidating mechanisms of tumor progression. Insights into AR activity at the PSA gene could be extended to transcriptional regulation of other AR target genes, which may be crucial in discerning prostate cancer progression. Ultimately, our improved understanding of AR‐regulated PSA expression could aid in developing viable therapies in treating and/or preventing advanced prostate cancer. © 2004 Wiley‐Liss, Inc.