bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of S6 kinase and p38 mitogen activated protein kinase pathways in strain‐induced alignment and proliferation of bovine aortic smooth muscle cells
Authors: Li Wei , Chen Quanhai , Mills Ira , Sumpio Bauer E. 
Published: March 2003

AbstractBovine aortic smooth muscle cell (SMC) phenotype can be altered by physical forces. This has been demonstrated by cyclic strain‐induced changes in proliferation and alignment. However, the intracellular coupling pathways remain ill defined. In the present study, we examined whether the p38 and S6 kinase pathway were involved in the mitogenic and morphological changes seen in SMCs exposed to cyclic strain. We seeded bovine aortic SMCs on silastic membranes that were deformed with 150‐mmHg vacuum. Cyclic strain induced both alignment and proliferation of SMCs. SB202190, a specific inhibitor of p38, hindered SMC alignment, but not proliferation. Rapamycin, a specific inhibitor of the mTOR‐S6 kinase pathway, attenuated strain‐induced proliferation, but not alignment. Peak activation of p38 and S6 kinase was 351 ± 76.9% at 5 min and 363 ± 56.2% at 60 min compared with static control, respectively (P < 0.05). The results suggest that strain‐induced SMC alignment is dependent on activation of p38, but not S6 kinase. Strain induced SMC proliferation is S6 kinase, but not p38 activation, dependent. © 2003 Wiley‐Liss, Inc.
Expression and tyrosine phosphorylation of Cbl regulates macrophage chemokinetic and chemotactic movement
Authors: Caveggion Elena , Continolo Silvia , Pixley Fiona J. , Stanley E. Richard , Bowtell David D.L. , Lowell Clifford A. , Berton Giorgio 
Published: March 2003

AbstractPrimary macrophages isolated from hck−/−fgr−/− mice display altered morphology and F‐actin cytoskeletal structures and reduced migration. The ability of phorbol myristyl acetate (PMA), a protein kinase C activator that has been reported to increase macrophage spreading and carcinoma cell motility, to rescue these hck−/−fgr−/− defects was tested. Although PMA‐treated wild‐type and hck−/−fgr−/− macrophages exhibited a similar flattened, spread phenotype, PMA did not rescue the hck−/−fgr−/− macrophage migration defect. Instead, both PMA‐treated wild type and hck−/−fgr−/− macrophages were defective in spontaneous and chemotactic migration and tyrosine phosphorylation of the Cbl protooncoprotein was decreased in both. Moreover, c‐cbl−/− macrophages displayed the same impairment of motility as hck−/−fgr−/− macrophages and a similar morphology with less polarization and more dorsal ruffling than wild‐type macrophages. As Hck and Fgr expression and activity were not decreased in c‐cbl−/− macrophages, these results suggest that Cbl is likely to be an important downstream mediator of the Src family kinase‐regulated macrophage motility pathway. © 2003 Wiley‐Liss, Inc.
Heregulin and retinoids synergistically induce branching morphogenesis of breast cancer cells cultivated in 3D collagen gels
Authors: Offterdinger Martin , Schneider Sonja M. , Grunt Thomas W. 
Published: March 2003

AbstractC‐erbB and retinoid receptor signaling control mammary epithelial cell proliferation, differentiation, and morphology. Here, we examined the morphogenetic activities of c‐erbB specific ligands such as heregulin and of retinoids on non‐malignant (primary, MTSV1‐7) and malignant (T47D, SKBR‐3) human mammary epithelial cells (HMEC) cultivated in 3D collagen type I gels. These cells are positive for both c‐erbB and retinoid receptors. Non‐malignant primary HMEC spontaneously formed branched structures in collagen, whereas SV40 large T antigen‐immortalized non‐tumorigenic MTSV1‐7 spontaneously formed balls and required heregulin or retinoid X receptor α‐selective retinoid Ro 25‐7386 for branching, which was further stimulated by combination of both types of agents. In malignant cells, heregulin alone induced ball formation and cooperated either with Ro 25‐7386 (T47D) or with retinoic acid receptor α‐selective AM580 (SKBR‐3) for branching morphogenesis, which was accompanied by changes in the subcellular distribution of α2β1‐integrin and E‐cadherin, and by down‐regulation of c‐erbB‐2, ‐3, or ‐4. Heregulin and/or retinoids correspondingly increased the integrin‐dependent adhesion of malignant cells to type I collagen. Our data demonstrate cooperative signaling of c‐erbB and retinoid receptor pathways at the levels of morphogenesis and immunophenotypic differentiation. © 2003 Wiley‐Liss, Inc.
Inhibition of protein kinase C decreases prostaglandin‐induced breakdown of the blood‐retinal barrier
Authors: Saishin Yoshitsugu , Saishin Yumiko , Takahashi Kyoichi , Melia Michele , Vinores Stanley A. , Campochiaro Peter A. 
Published: March 2003

AbstractBreakdown of the blood‐retinal barrier (BRB) occurs in several retinal diseases and is a major cause of visual loss. Vascular endothelial growth factor (VEGF) has been implicated as a cause of BRB breakdown in diabetic retinopathy and other ischemic retinopathies, and there is evidence to suggest that other vasopermeability factors may act indirectly through VEGF. In this study, we investigated the effect of several receptor kinase inhibitors on BRB breakdown resulting from VEGF, tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), insulin‐like growth factor‐1 (IGF‐1), prostaglandin E1 (PGE1), or PGE2. Inhibitors of VEGF receptor kinase, including PKC412, PTK787, and SU1498, decreased VEGF‐induced breakdown of the BRB. None of the inhibitors blocked leakage caused by TNF‐α, IL‐1β, or IGF‐1 and only PKC412, an inhibitor of protein kinase C (PKC) as well as VEGF and platelet‐derived growth factor (PDGF) receptor kinases, decreased leakage caused by prostaglandins. Since the other inhibitors of VEGF and/or PDGF receptor kinases that do not also inhibit PKC had no effect on prostaglandin‐induced breakdown of the BRB, these data implicate PKC in retinal vascular leakage caused by prostaglandins. PKC412 may be useful for treatment of post‐operative and inflammatory macular edema, in which prostaglandins play a role, as well as macular edema associated with ischemic retinopathies. © 2003 Wiley‐Liss, Inc.
Activation of P2Y2 receptor induces c‐FOS protein through a pathway involving mitogen‐activated protein kinases and phosphoinositide 3‐kinases in HeLa cells
Authors: Muscella Antonella , Elia Maria Giovanna , Greco Simona , Storelli Carlo , Marsigliante Santo 
Published: March 2003

AbstractThe effects of P2Y2 purinoceptor activation on c‐Fos expression and the signaling pathways evoked by extracellular ATP/UTP in HeLa cells were investigated. We found that P2Y2 activation induced c‐Fos protein and phosphorylated the extracellular signal‐regulated kinases 1 and 2 (ERK1/2). The P2Y2‐stimulated c‐Fos induction was partly blocked (a) by U73122, a phospholipase C inhibitor, (b) by Gö6976, a conventional PKC inhibitor, (c) by PD098059, a mitogen‐activated protein kinase kinase inhibitor, and, moreover, (d) by the inhibitors of phosphoinositide 3‐kinases (PI3K), LY294002 and wortmannin. When Gö6976 and PD098059, or Gö6976 and wortmannin, were combined there was a totally inhibition of P2Y2‐induced c‐Fos increase. Either U73122 or Gö6976 did not inhibit ERK1/2 phosphorylation induced by ATP/UTP, while it was inhibited by LY294002 (or wortmannin) and by staurosporine. Additionally, wortmannin inhibited the cytosol‐to‐membrane translocation of PKC‐ε induced by ATP/UTP. These data indicated that agonist‐induced PI3K and downstream PKC‐ε activation mediated the effect of ATP/UTP on ERK1/2 activation. To test the biological consequences of ERK1/2 activation, the effect of P2Y2 on cell functions were examined. P2Y2 stimulation increased cell proliferation and this effect was attenuated by PD098059 in a dose‐dependent manner, thereby indicating that the ERK pathway mediates mitogenic signaling by P2Y2. In conclusion, the activation of conventional PKCs through P2Y2 receptor acts in concert with ERK and PI3K/PKC‐ε pathways to induce c‐Fos protein and HeLa cell proliferation. © 2003 Wiley‐Liss, Inc.
Differential effects of quercetin, a natural polyphenolic flavonoid, on L‐Type calcium current in pituitary tumor (GH3) cells and neuronal NG108‐15 cells
Authors: Wu Sheng‐Nan , Chiang Hung‐Ting , Shen Ai‐Yu , Lo Yuk‐Keung 
Published: March 2003

AbstractThe effects of quercetin, a natural polyphenolic compound, on voltage‐dependent L‐type Ca2+ current (ICa,L) in rat pituitary GH3 cells were investigated with the aid of the whole‐cell voltage‐camp technique. Quercetin (0.5–200 μM) stimulated ICa,L in a concentration‐dependent manner. The current–voltage (I–V) relationship of ICa,L was slightly shifted to more negative potentials in the presence of quercetin. The EC50 value of the quercetin‐induced stimulation of ICa,L was about 7 μM. The presence of quercetin (5 μM) shifted the steady state inactivation curve of ICa,L to a more negative potential by approximately −10 mV. Although quercetin might increase intracellular cyclic AMP, sp‐cAMPS did not affect ICa,L. In addition, neither flavone nor wortmannin had any effect on the amplitude of ICa,L, while epicatechin and genistein slightly suppressed it. Quercetin (50 μM) decreased the amplitude of tetrodotoxin‐sensitive Na+ current in GH3 cells. Under current‐clamp configuration, quercetin could increase the firing frequency of actions potentials. Conversely, in NG108‐15 neuronal cells, quercetin suppressed the amplitude of ICa,L. The quercetin‐induced inhibition of ICa,L was abolished in NG108‐15 cells preincubated with t‐butyl hydroperoxide (1 mM). Quercetin‐mediated stimulation of ICa,L in GH3 cells was presumably not associated with the level of intracellular cyclic AMP, or with the activity of tyrosine or phosphoinositide 3‐kinases. Therefore, the effects of quercetin on ion currents may, at least in part, contribute to the underlying mechanisms through which it affects neuronal or neuroendocrine function. © 2003 Wiley‐Liss, Inc.
Activation of extracellular signal‐regulated kinases ERK1 and ERK2 induces Bcl‐xL up‐regulation via inhibition of caspase activities in erythropoietin signaling
Authors: Mori Masaki , Uchida Mie , Watanabe Tomoko , Kirito Keita , Hatake Kiyohiko , Ozawa Keiya , Komatsu Norio 
Published: March 2003

AbstractErythropoietin (EPO) can rescue erythroid cells from apoptosis during erythroid development, leading to red cell production. However, the detailed mechanism of how EPO protects erythroid cells from apoptosis is still open to question. To address this problem, we used a human EPO‐dependent leukemia cell line UT‐7/EPO and normal erythroid progenitor cells. After deprivation of EPO, UT‐7/EPO cells underwent apoptosis, accompanied by down‐regulation of the Bcl‐xL protein. In addition, the cleaved products of caspase‐3, p11 and p21, and a few cleaved forms of inhibitor of caspase‐activated DNase (ICAD) were detected in these cells. When the cells were pre‐treated with the pancaspase inhibitor Z‐VAD‐FMK, the ratio of apoptotic cells was significantly reduced, suggesting that EPO protects the UT‐7/EPO cells from apoptosis via inhibition of caspase activities. When an MEK 1/2 inhibitor U0126 inhibited activities of extracellular signal‐regulated kinases (ERKs), the expression of Bcl‐xL protein was down‐regulated and subsequently apoptosis was induced. Interestingly, Z‐VAD‐FMK blocked U0126‐induced down‐regulation of Bcl‐xL protein and apoptosis, strongly suggesting that Bcl‐xL expression is regulated by caspases which lies downstream of ERK activation pathway in EPO signaling. Importantly, these findings were also observed in normal erythroid progenitor cells. In conclusion, the activation of ERKs by EPO up‐regulates Bcl‐xL expression via inhibition of caspase activities, resulting in the protection of erythroid cells from apoptosis. © 2003 Wiley‐Liss, Inc.
VEGF‐TRAPR1R2 suppresses choroidal neovascularization and VEGF‐induced breakdown of the blood–retinal barrier
Authors: Saishin Yoshitsugu , Saishin Yumiko , Takahashi Kyoichi , Silva Raquel Lima e , Hylton Donna , Rudge John S. , Wiegand Stanley J. , Campochiaro Peter A. 
Published: March 2003

AbstractVascular endothelial growth factor (VEGF) plays a central role in the development of retinal neovascularization and diabetic macular edema. There is also evidence suggesting that VEGF is an important stimulator for choroidal neovascularization. In this study, we investigated the effect of a specific inhibitor of VEGF, VEGF‐TRAPR1R2, in models for these disease processes. VEGF‐TRAPR1R2 is a fusion protein, which combines ligand binding elements taken from the extracellular domains of VEGF receptors 1 and 2 fused to the Fc portion of IgG1. Subcutaneous injections or a single intravitreous injection of VEGF‐TRAPR1R2 strongly suppressed choroidal neovascularization in mice with laser‐induced rupture of Bruch's membrane. Subcutaneous injection of VEGF‐TRAPR1R2 also significantly inhibited subretinal neovascularization in transgenic mice that express VEGF in photoreceptors. In two models of VEGF‐induced breakdown of the blood–retinal barrier (BRB), one in which recombinant VEGF is injected into the vitreous cavity and one in which VEGF expression is induced in the retina in transgenic mice, VEGF‐TRAPR1R2 significantly reduced breakdown of the BRB. These data confirm that VEGF is a critical stimulus for the development of choroidal neovascularization and indicate that VEGF‐TRAPR1R2 may provide a new agent for consideration for treatment of patients with choroidal neovascularization and diabetic macular edema. © 2003 Wiley‐Liss, Inc.
Role of protein kinase C α in calcium induced keratinocyte differentiation: Defective regulation in squamous cell carcinoma
Authors: Yang Lee Chuan , Ng Dean C. , Bikle Daniel D. 
Published: March 2003

AbstractCalcium induces both involucrin and transglutaminase‐K in normal keratinocytes (NHK) but not in squamous carcinoma cell lines (SCC). The protein kinase C (PKC) agonist phorbol myristoyl acetate potentiates and the PKC antagonist Ro31‐8220 blocks the ability of calcium to stimulate the involucrin promoter in normal human keratinocytes but not in SCC4. We thus examined the ability of calcium to regulate the levels of five PKC isozymes in NHK and two SCC. In the normal keratinocytes, the levels of PKC [alpha], PKC [delta], PKC [eta], and PKC [zeta] increased over the first one to two weeks in a calcium‐and time‐dependent manner. PKC [epsilon] decreased in a time‐and calcium‐dependent fashion over the three‐week period. All five isozymes showed little change during culture in SCC4 at any calcium concentration. Calcium and time of culture had partial effects on SCC12B2, a carcinoma that shows partial differentiation characteristics. Since PKC [alpha] is the only calcium responsive PKC isozyme in keratinocytes and most likely to be directly involved in calcium induced differentiation, we evaluated the effect of inhibiting its production with antisense oligonucleotides on calcium‐regulated markers of differentiation. We found that the PKC [alpha] specific antisense oligonucleotide blocked calcium stimulated involucrin promoter activity as well as PKC [alpha], involucrin, and transglutaminase protein production, whereas the sense oligonucleotide control did not. We conclude that although a number of PKC isozymes are regulated during calcium‐induced differentiation, PKC [alpha] plays a necessary role in mediating calcium‐induced differentiation. Failure to regulate PKC [alpha] in SCC4 may underlie at least part of the failure of calcium to promote differentiation in these cells. © 2003 Wiley‐Liss, Inc.
EGF‐responsive rat neural stem cells: Molecular follow‐up of neuron and astrocyte differentiation in vitro
Authors: Jori F.P. , Galderisi U. , Piegari E. , Cipollaro M. , Cascino A. , Peluso G. , Cotrufo R. , Giordano A. , Melone M.A.B. 
Published: March 2003

AbstractNeural stem cells (NSCs) could be very useful for the “cell therapy” treatment of neurological disorders. For this reason basic studies aiming to well characterize the biology of NSCs are of great interest. We carried out a molecular and immunocytochemical analysis of EGF‐responsive NSCs obtained from rat pups. After the initial growth of NSCs as floating neurospheres in EGF‐containing medium, cells were plated on poly‐L‐ornithine‐coated dishes either in the presence or absence of EGF. We followed cell differentiation and apoptosis for 21 days in vitro and analyzed the expression levels of some genes having a major role in these processes, such as pRB, pRB2/p130, p27, and p53. We observed that EGF impairs neuronal differentiation. Furthermore, in the absence of mitogens, apoptosis, which appeared to proceed through the “p53 network,” was significantly lower than in the presence of EGF. The cyclin kinase inhibitor p27, while important for cell cycle exit, seemed dispensable for cell survival and differentiation. © 2003 Wiley‐Liss, Inc.
β‐adrenergic receptor‐mediated DNA synthesis in neonatal rat cardiac fibroblasts proceeds via a phosphatidylinositol 3‐kinase dependent pathway refractory to the antiproliferative action of cyclic AMP
Authors: Colombo Federico , Gosselin Hugues , El‐Helou Viviane , Calderone Angelino 
Published: March 2003

AbstractThe following study was undertaken to elucidate the cytoskeletal phenotype of neonatal rat cardiac fibroblasts (NNCF) and the signaling pathways coupled to β‐adrenergic receptor stimulated DNA synthesis. The cytoskeletal proteins vimentin, and smooth muscle α‐actin were detected in NNCF, suggestive of a myofibroblast phenotype. Isoproterenol (ISO) treatment stimulated 3H‐thymidine uptake, and concomitantly increased intracellular cyclic AMP levels. However, cyclic AMP‐elevating agents markedly decreased DNA synthesis. Coincident with growth, ISO‐stimulated phosphatidylinositol 3‐kinase (PI3‐K) activity, and the PI3‐K inhibitor LY294002 abrogated enzyme activity, and DNA synthesis. Unexpectedly, the serine/threonine kinase protein kinase Bα (PKBα), a putative downstream target of PI3‐K, was dephosphorylated following ISO treatment. Despite PKBα inactivation, the phosphorylation of its putative downstream target, the pro‐apoptotic enzyme glycogen synthase kinase‐3α was significantly increased in response to ISO. These latter effects of ISO were mimicked by the cyclic AMP‐elevating agent forskolin. Lastly, ISO treatment increased p70 ribosomal S6 kinase (p70S6K) phosphorylation, as reflected by an upward electrophoretic mobility shift. The pretreatment with rapamycin abrogated the ISO‐mediated mobility shift of p70S6K, and DNA synthesis. Collectively, these data demonstrate that NNCF express a myofibroblast phenotype, and β‐adrenergic agonists promote DNA synthesis via a PI3‐K‐dependent pathway involving p70S6K. Although unable to suppress ISO‐stimulated DNA synthesis, cyclic AMP can influence specific downstream targets of PI3‐K highlighting a novel crosstalk between these signaling pathways. © 2003 Wiley‐Liss, Inc.
RET and NTRK1 proto‐oncogenes in human diseases
Authors: Alberti Luisella , Carniti Cristiana , Miranda Claudia , Roccato Emanuela , Pierotti Marco A. 
Published: March 2003

AbstractRET and NTRK1 are receptor tyrosine kinase (RTK) proteins which play a role in the development and maturation of specific component of the nervous system. Their alterations have been associated to several human diseases, including some forms of cancer and developmental abnormalities. These features have contributed to the concept that one gene can be responsible for more than one disease. Moreover, both genes encoding for the two RTKs show genetic alterations that belong to either “gain of function” or “loss of function” class of mutations. In fact, receptor rearrangements or point mutations convert RET and NTRK1 in dominantly acting transforming genes leading to thyroid tumors, whereas inactivating mutations, associated with Hirschsprung's disease (HSCR) and congenital insensitivity to pain with anhidrosis (CIPA), impair RET and NTRK1 functions, respectively. In this review we have summarized the main features of the two receptors, their physiological and pathological roles. In addition, we attempted to identify the correlations between the different genetic alterations and the related pathogenetic mechanisms. © 2003 Wiley‐Liss, Inc.
Identification of cathepsin K as a novel marker of adiposity in white adipose tissue
Authors: Chiellini Chiara , Costa Mario , Novelli Silvia E. , Amri Ez‐Zoubir , Benzi Luca , Bertacca Anna , Cohen Paul , Del Prato Stefano , Friedman Jeffrey M. , Maffei Margherita 
Published: March 2003

AbstractIn obesity, adipocytes undergo dramatic morphological and molecular changes associated with alterations in their gene expression profile. To identify genes differentially modulated in white adipose tissue (WAT) of obese db/db mice compared to wild type (wt) mice, we utilized RNA fingerprinting. Among the 52 candidates that we identified, we focused here on cathepsin K (ctsk), a cysteine protease, prevalently localized in lysosomes and involved in bone extracellular matrix degradation. In db/db mice, WAT ctsk mRNA was elevated 5.9‐fold, as were Mitf and TFE3 (2‐ and 3.3‐fold respectively), two transcription factors involved in ctsk induction in osteoclasts. Moreover, the level of WAT ctsk mRNA was increased in other obese models including Ay, fat, and tubby (2.8‐, 3.2‐, and 4.9‐fold respectively) and decreased in mice undergoing weight loss. Despite the ubiquitous distribution of the ctsk transcript, we demonstrated that the obesity related increase is specific to the adipocytes. Further, in vitro experiments proved that the abundance of ctsk transcript increases upon adipose conversion of the established cell line of preadipocytes 3T3‐F442A. In addition, ctsk gene expression was examined in adipose tissue of 21 lean and obese male subjects and significant correlations with BMI (r = 0.54, P = 0.012) and plasma leptin levels (r = 0.54, P = 0.015) were found. In conclusion, the WAT of obese db/db mice exhibits a different expression profile from that of the wt mice, and cathepsin K can be considered a novel marker of obesity and a target for the inhibition of adipose mass growth. © 2003 Wiley‐Liss, Inc.
Cell death regulation by the Bcl‐2 protein family in the mitochondria
Authors: Tsujimoto Yoshihide 
Published: March 2003

AbstractAn increase in the permeability of the outer mitochondrial membrane is central to apoptotic cell death, since it leads to the release of several apoptogenic factors, such as cytochrome c and Smac/Diablo, into the cytoplasm that activate downstream death programs. During apoptosis, the mitochondria also release AIF and endonuclease G, both of which are translocated to the nucleus and are implicated in apoptotic nuclear changes that occur in a caspase‐independent manner. Mitochondrial membrane permeability is directly controlled by the major apoptosis regulator, i.e., the Bcl‐2 family of proteins, mainly through regulation of the formation of apoptotic protein‐conducting pores in the outer mitochondrial membrane, although the precise molecular mechanisms are still not completely understood. Here, I focus on the mechanisms by which Bcl‐2 family members control the permeability of mitochondrial membrane during apoptosis. © 2003 Wiley‐Liss, Inc.