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991.
Contribution of the cyclic nucleotide phosphodiesterases PdeA and PdeB to adaptation of Myxococcus xanthus cells to osmotic or high-temperature stress 下载免费PDF全文
A tBLASTn search of the Myxococcus xanthus genome database at The Institute for Genomic Research (TIGR) identified three genes (pdeA, pdeB, and pdeC) that encode proteins homologous to 3',5'-cyclic nucleotide phosphodiesterase. pdeA, pdeB, and pdeC mutants, constructed by replacing a part of the gene with the kanamycin or tetracycline resistance gene, showed normal growth, development, and germination under nonstress conditions. However, the spores of mutants, especially the pdeA and pdeB mutants, placed under osmotic stress germinated earlier than the wild-type spores. The phenotype was the opposite of that of the receptor-type adenylyl cyclase (cyaA or cyaB) mutant. Also, pdeA and pdeB mutants were found to have impaired growth under the condition of high-temperature stress. Intracellular cyclic AMP (cAMP) levels of pdeA or pdeB mutant cells under these stressful conditions were about 1.3-fold to 2.0-fold higher than those of wild-type cells. These results suggest that PdeA and PdeB may be involved in osmotic adaptation during spore germination and temperature adaptation during vegetative growth through the regulation of cAMP levels. 相似文献
992.
Shell of the adult hermit crab has some important roles for its fitness. In the same time, the shell size often limits the body growth of its owner. To grow the body size larger, the individual must change the shell to another larger shell. If the individual cannot get another larger one, the individual has to suppress the body size growth as the occupied shell size allows. Growth suppression would result in the lower fitness. With a simple mathematical model, we consider the criterion about whether the individual should try to change the shell or not in order to get the higher fitness. We show that the optimality of a shell change behavior has a relation with the body size and the season length for the shell change. They also affect the optimal timing for the shell change. It is implied that the probability of the success in a shell change and the cost for the shell change behavior do not affect the optimal timing for the shell change at all but significantly do the optimality of the behavioral choice. 相似文献
993.
Toru Takeo Yukie Haruguchi Hiromi Machida Yoshiko Nakagawa Toyokazu Matsuguma Norihiko Shimizu Motohito Goto Masayuki Anzai Koji Nomaru 《Cryobiology》2009,58(2):196-202
Cryopreservation of 2-cell embryos is an effective technology for storage of genetically engineered mouse strains. Transport of genetically engineered mice between laboratories has frequently been performed using such cryopreserved 2-cell embryos. However, the receiving laboratory requires proficient skills and special instruments to obtain live young from cryopreserved and transported embryos. Therefore, in this study, we tried to address the storage and transport of vitrified/warmed 2-cell embryos at a cold temperature. In cold storage experiments, the development rates of 2-cell embryos stored in M2 medium for 24, 48 and 72 h into blastocysts were relatively high (83%, 63% and 43%, respectively). Although, 2-cell embryos stored in PB1 and mWM maintained the developmental potency for 24 h, the rates were markedly decreased to low levels after 48 h (PB1: 0%; mWM: 5%). In transport experiments, many pups were obtained from vitrified/warmed 2-cell embryos transported at a cold temperature in all receiving laboratories (incidence of successful development: 49%; 249/511). In summary, short-term storage and transport of vitrified/warmed 2-cell embryos in M2 medium at a cold temperature can maintain their ability to develop into live young. 相似文献
994.
Norihisa Nishimichi Fumiko Higashikawa Hiromi H. Kinoh Yoshiko Tateishi Haruo Matsuda Yasuyuki Yokosaki 《The Journal of biological chemistry》2009,284(22):14769-14776
Osteopontin (OPN) is a cytokine and ligand for multiple members of the
integrin family. OPN undergoes the in vivo polymerization catalyzed
by cross-linking enzyme transglutaminase 2, which consequently increases the
bioactivity through enhanced interaction with integrins. The integrin
α9β1, highly expressed on neutrophils, binds to the sequence
SVVYGLR only after intact OPN is cleaved by thrombin. The SVVYGLR sequence
appears to be cryptic in intact OPN because α9β1 does not recognize
intact OPN. Because transglutaminase 2-catalyzed polymers change their
physical and chemical properties, we hypothesized that the SVVYGLR site might
also be exposed on polymeric OPN. As expected, α9β1 turned into a
receptor for polymeric OPN, a result obtained by cell adhesion and migration
assays with α9-transfected cells and by detection of direct binding of
recombinant soluble α9β1 with colorimetry and surface plasmon
resonance analysis. Because the N-terminal fragment of thrombin-cleaved OPN, a
ligand for α9β1, has been reported to attract neutrophils, we next
examined migration of neutrophils to polymeric OPN using time-lapse
microscopy. Polymeric OPN showed potent neutrophil chemotactic activity, which
was clearly inhibited by anti-α9β1 antibody. Unexpectedly,
mutagenesis studies showed that α9β1 bound to polymeric OPN
independently of the SVVYGLR sequence, and further, SVVYGLR sequence of
polymeric OPN was cryptic because SVVYGLR-specific antibody did not recognize
polymeric OPN. These results demonstrate that polymerization of OPN generates
a novel α9β1-binding site and that the interaction of this site
with the α9β1 integrin is critical to the neutrophil chemotaxis
induced by polymeric OPN.Acidic phosphorylated secreted glycoprotein osteopontin
(OPN),4 known as a
cytokine, has multiple functions, including roles in tissue remodeling,
fibrosis, mineralization, immunomodulation, inflammation, and tumor metastasis
(1–3).
OPN is also an integrin ligand. At least nine integrins can function as OPN
receptors. α5β1, α8β1, αvβ1, αvβ3,
αvβ5 (1), and
αvβ6 (4) recognize
the linear tripeptide RGD, and α9β1, α4β1, and
α4β7 recognize the sequence, SVVYGLR
(5), adjacent to RGD but only
after OPN has been cleaved by the protease, thrombin
(Fig. 1).Open in a separate windowFIGURE 1.Schematic diagram of OPN. Two integrin-binding sites
(boxed), a thrombin cleavage site (arrow), and a putative
transglutamination site (circled) are shown. The term
thrombin-cleaved nOPN is defined as in the figure.The overlap of receptors for OPN does not necessarily mean that these
integrins play redundant roles in cellular responses to OPN because the
patterns of integrin expression and utilization vary widely among cell types.
In addition, interactions of different integrins with a single ligand can
exert distinct effects on cell behavior in a single cell type. For example, we
have previously reported that signals by ligation of αvβ3,
αvβ6, or α9β1 to a single ligand, tenascin-C,
differently affected cell adhesion, spreading, and proliferation of the colon
cancer cell line, SW480 (6).
Furthermore, intact OPN or thrombin- or matrix metalloproteinase-cleaved OPN
interact with distinct subsets of integrins and exhibit distinct effects on
cell behavior (4,
7,
8). Collectively, some of the
functional diversity of OPN could be attributed to this multiplicity of
receptors and responses. We have recently shown that polymerization of OPN
results in enhanced biological activity
(9). We thus set out to
determine whether polymerized OPN exerts its effects through unique
interactions with integrins.OPN is polymerized by transglutaminase 2 (TG2, EC 2.3.2.13)
(10) that catalyzes formation
of isopeptide cross-links between glutamine and lysine residues in substrate
proteins (11) including OPN.
Polymeric OPN has been identified in vivo in bone
(12) and calcified aorta
(13). We have previously
reported that upon polymerization, OPN displays increased integrin binding
accompanied by enhanced cell adhesion, spreading, migration, and focal contact
formation (9). However, very
little is known about how polymeric OPN induces its biological effects.Integrin α9β1, highly expressed on neutrophils
(14), does not act as a
receptor for intact OPN but does bind to an N-terminal fragment of OPN (nOPN)
that is generated by thrombin cleavage
(15) through the new
C-terminal sequence, SVVYGLR. Protein polymerization can expose otherwise
cryptic domains (16), so we
hypothesized that the SVVYGLR site might be exposed upon polymerization and
serve as a binding site for α9β1. In the present study, we
demonstrate that α9β1 is indeed a receptor for polymeric OPN and
that neutrophil migration induced by polymeric OPN is largely mediated by this
interaction. However, mutational analysis and antibody studies demonstrate
that this interaction does not involve the SVVYGLR site, suggesting the
presence of de novo binding site in polymeric OPN. 相似文献
995.
Masakiyo Sakaguchi Ken Kataoka Fernando Abarzua Ryuta Tanimoto Masami Watanabe Hitoshi Murata Swe Swe Than Kaoru Kurose Yuji Kashiwakura Kazuhiko Ochiai Yasutomo Nasu Hiromi Kumon Nam-ho Huh 《The Journal of biological chemistry》2009,284(21):14236-14244
We previously showed that the tumor suppressor gene
REIC/Dkk-3, when overexpressed by an adenovirus (Ad-REIC),
exhibited a dramatic therapeutic effect on human cancers through a mechanism
triggered by endoplasmic reticulum stress. Adenovirus vectors show no target
cell specificity and thus may elicit unfavorable side effects through
infection of normal cells even upon intra-tumoral injection. In this study, we
examined possible effects of Ad-REIC on normal cells. We found that infection
of normal human fibroblasts (NHF) did not cause apoptosis but induced
production of interleukin (IL)-7. The induction was triggered by endoplasmic
reticulum stress and mediated through IRE1α, ASK1, p38, and IRF-1. When
Ad-REIC-infected NHF were transplanted in a mixture with untreated human
prostate cancer cells, the growth of the cancer cells was significantly
suppressed. Injection of an IL-7 antibody partially abrogated the suppressive
effect of Ad-REIC-infected NHF. These results indicate that Ad-REIC has
another arm against human cancer, an indirect host-mediated effect because of
overproduction of IL-7 by mis-targeted NHF, in addition to its direct effect
on cancer cells.Cancer cells, like normal cells, cannot be free from regulation by other
cells in the body (1). The
microenvironment can exert both promotive and suppressive effects on malignant
cells (2). The embryonic
environment has been shown to suppress malignant phenotypes
(3,
4), and this was recently
indicated to be due to suppression of Nodal function by Lefty
(5). Cells comprising cancer
stroma in adult tissues are also involved in tumor suppression
(6,
7). Mobilization of such
potential tumor-suppressive effects of the microenvironment would provide an
additional arm for cancer therapy
(8).Adenovirus vectors combined with appropriate cargo genes have great
potential in cancer gene therapy because of their high infection efficiency
and marginal genotoxicity (9).
However, they show no target cell specificity and thus may also infect normal
cells present in the surroundings of cancer cells. Provided that the
interaction between cancer cells and normal cells is relevant to
progression/suppression of cancer, it is critically important to understand
not only cell autonomous phenomena in individual cell types infected by a
therapeutic virus vector but also potential effects of the therapeutic virus
vector on the composite system of interacting cell populations.We have been studying the possible utility of an adenovirus vector carrying
the tumor suppressor gene REIC/Dkk-3 (Ad-REIC) for gene
therapy against human cancer. REIC/Dkk-3 was first
identified as a gene that was down-regulated in association with
immortalization of normal human fibroblasts
(NHF)2
(10). Expression of
REIC/Dkk-3 gene was shown to be reduced in many human cancer
cells and tissues, including prostate cancer, renal clear cell carcinoma,
testicular cancer, and non-small cell lung cancer
(11–14),
probably due to hypermethylation of the promoter
(15). A single injection of
Ad-REIC into tumors formed by transplantation of human prostate cancer cells
(PC3 cells) into mice resulted in 4 of 5 mice becoming tumor-free
(13). Subsequently, we found
that Ad-REIC was effective also for human cancers derived from the testis,
pleura, and breast (14,
16,
17). The potent multitargeting
anti-cancer function of Ad-REIC shows great promise for clinical application,
which will be shortly initiated.REIC/Dkk-3 is a highly glycosylated secretory protein and
is considered to physiologically act on cells via a yet-unidentified receptor.
However, we found that the induction of apoptosis in cancer cells by Ad-REIC
was because of endoplasmic reticulum (ER) stress loaded by overproduction of
the REIC/Dkk-3 protein and that exogenously applied REIC/Dkk-3 protein showed
no apoptosis inducing activity for cancer cells
(13,
14). Activation of c-Jun
N-terminal kinase (JNK) was shown to be an essential step for the induction of
apoptosis by Ad-REIC. ER stress is evoked by overload of unfolded/misfolded
proteins in the ER, and eukaryotic cells respond to the threat by activating
an unfolded protein response, i.e. attenuating de novo
protein synthesis, promoting protein degradation by proteasomes, and inducing
chaperone proteins to help proper folding of proteins
(18). When ER stress remains
at a level manageable by the unfolded protein response, cells can survive. On
the other hand, overload of unfolded/misfolded protein beyond the cellular
adoptive response leads to apoptotic cell death. Although Ad-REIC strongly
induces apoptosis in many types of cancer cells, normal cells thus far
examined are resistant to Ad-REIC-induced apoptosis despite expression of
REIC/Dkk-3 at a level similar to that in cancer cells
(13). The aim of this study
was to determine the mechanisms of differential response of normal cells and
cancer cells to Ad-REIC and to reveal the possible effect of Ad-REIC on a
composite interacting system of normal cells and cancer cells. We found that
Ad-REIC induced NHF to produce IL-7 via ER stress-triggered activation of p38.
Furthermore, Ad-REIC-infected NHF significantly suppressed tumor growth of
untreated PC3 cells transplanted in a mixture in vivo. These results
mean that, in addition to its direct cancer cell-killing activity, Ad-REIC has
another mechanism of action against human cancer, an indirect host-mediated
effect because of overproduction of IL-7 by mis-targeted NHF. 相似文献
996.
Junko Nio-Kobayashi Hiromi Takahashi-Iwanaga Toshihiko Iwanaga 《The journal of histochemistry and cytochemistry》2009,57(1):41-50
Galectin, an animal lectin that recognizes β-galactoside of glycoconjugates, is abundant in the gut. This IHC study showed the subtype-specific localization of galectin in the mouse digestive tract. Mucosal epithelium showed region/cell-specific localization of each galectin subtype. Gastric mucous cells exhibited intense immunoreactions for galectin-2 and galectin-4/6 with a limited localization of galectin-3 at the surface of the gastric mucosa. Electron microscopically, galectin-3 immunoreactivity coated indigenous bacteria on the gastric surface mucous cells. Epithelial cells in the small intestine showed characteristic localizations of galectin-2 and galectin-4/6 in the cytoplasm of goblet cells and the baso-lateral membrane of enterocytes in association with maturation, respectively. Galectin-3 expressed only at the villus tips was concentrated at the myosin-rich terminal web of fully matured enterocytes. Epithelial cells of the large intestine contained intense immunoreactions for galectin-3 and galectin-4/6 but not for galectin-2. The stratified squamous epithelium of the forestomach was immunoreactive for galectin-3 and galectin-7, but the basal layer lacked galectin-3 immunoreactivity. Outside the epithelium, only galectin-1 was localized in the connective tissue, smooth muscles, and neuronal cell bodies. The subtype-specific localization of galectin suggests its important roles in host-pathogen interaction and epithelial homeostasis such as membrane polarization and trafficking in the gut. (J Histochem Cytochem 57:41–50, 2009) 相似文献
997.
Morishita Y Yoshioka Y Satoh H Nojiri N Nagano K Abe Y Kamada H Tsunoda S Nabeshi H Yoshikawa T Tsutsumi Y 《Biochemical and biophysical research communications》2012,420(2):297-301
Amorphous nanosilica particles (nSP) are being utilized in an increasing number of applications such as medicine, cosmetics, and foods. The reduction of the particle size to the nanoscale not only provides benefits to diverse scientific fields but also poses potential risks. Several reports have described the in vivo and in vitro toxicity of nSP, but few studies have examined their effects on the male reproductive system. The aim of this study was to evaluate the testicular distribution and histologic effects of systemically administered nSP. Mice were injected intravenously with nSP with diameters of 70 nm (nSP70) or conventional microsilica particles with diameters of 300 nm (nSP300) on two consecutive days. The intratesticular distribution of these particles 24h after the second injection was analyzed by transmission electron microscopy. nSP70 were detected within sertoli cells and spermatocytes, including in the nuclei of spermatocytes. No nSP300 were observed in the testis. Next, mice were injected intravenously with 0.4 or 0.8 mg nSP70 every other day for a total of four administrations. Testes were harvested 48 h and 1 week after the last injection and stained with hematoxylin-eosin for histologic analysis. Histologic findings in the testes of nSP70-treated mice did not differ from those of control mice. Taken together, our results suggest that nSP70 can penetrate the blood-testis barrier and the nuclear membranes of spermatocytes without producing apparent testicular injury. 相似文献
998.
Iwabayashi M Taniyama Y Sanada F Azuma J Iekushi K Okayama K Chatterjee A Rakugi H Morishita R 《Biochemical and biophysical research communications》2012,423(1):79-84
BackgroundLipoprotein (a) (Lp(a)) is one of the risk factors for peripheral artery disease (PAD). Our previous report demonstrated that hepatocyte growth factor (HGF) gene therapy attenuated the impairment of collateral formation in Lp(a) transgenic mice. Since risk factors for atherosclerosis accelerate endothelial senescence and impair angiogenesis, we examined the role of Lp(a) in dysfunction and senescence of endothelial progenitor cells (EPC) and endothelial cells.MethodsIn vitro and in vivo incorporation assays were performed using ex-vivo expanded DiI-labeled human EPC. Senescence of cultured endothelial cells, production of oxidative stress and angiogenesis function were evaluated by SA-β-galactosidase staining, dihydroethidium (DHE) staining and Matrigel assay, respectively.ResultsEPC transplantation significantly stimulated recovery of ischemic limb perfusion, while EPC pre-treated with Lp(a) did not increase ischemic limb perfusion. Impairment of angiogenesis by EPC with Lp(a) was associated with a significant decrease in CD31-positive capillaries and DiI-labeled EPC. Importantly, Lp(a) significantly accelerated the onset of senescence and production of reactive oxygen species (ROS) in human aortic endothelial cells, accompanied by a significant increase in the protein expression of p53 and p21. On the other hand, HGF significantly attenuated EPC dysfunction, senescence, ROS production, and p53 and p21 expression induced by Lp(a).ConclusionLp(a) might affect atherosclerosis via acceleration of senescence, ROS production, and functional impairment of the endothelial cell lineage. HGF might have inhibitory effects on these atherogenic actions of Lp(a). 相似文献
999.
1000.