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991.
Teruaki Oku Mai Nakano Yutaka Kaneko Yusuke Ando Hiroki Kenmotsu Saotomo Itoh Makoto Tsuiji Yoshiyuki Seyama Satoshi Toyoshima Tsutomu Tsuji 《The Journal of biological chemistry》2012,287(51):42910-42920
The actin-binding protein p57/coronin-1, a member of the coronin protein family, is selectively expressed in hematopoietic cells and plays crucial roles in the immune response through reorganization of the actin cytoskeleton. We previously reported that p57/coronin-1 is phosphorylated by protein kinase C, and the phosphorylation down-regulates the association of this protein with actin. In this study we analyzed the phosphorylation sites of p57/coronin-1 derived from HL60 human leukemic cells by MALDI-TOF-MS, two-dimensional gel electrophoresis, and Phos-tag® acrylamide gel electrophoresis in combination with site-directed mutagenesis and identified Ser-2 and Thr-412 as major phosphorylation sites. A major part of p57/coronin-1 was found as an unphosphorylated form in HL60 cells, but phosphorylation at Thr-412 of p57/coronin-1 was detected after the cells were treated with calyculin A, a Ser/Thr phosphatase inhibitor, suggesting that p57/coronin-1 undergoes constitutive turnover of phosphorylation/dephosphorylation at Thr-412. A diphosphorylated form of p57/coronin-1 was detected after the cells were treated with phorbol 12-myristate 13-acetate plus calyculin A. We then assessed the effects of phosphorylation at Thr-412 on the association of p57/coronin-1 with actin. A co-immunoprecipitation experiment with anti-p57/coronin-1 antibodies and HL60 cell lysates revealed that β-actin was co-precipitated with the unphosphorylated form but not with the phosphorylated form at Thr-412 of p57/coronin-1. Furthermore, the phosphorylation mimic (T412D) of p57/coronin-1 expressed in HEK293T cells exhibited lower affinity for actin than the wild-type or the unphosphorylation mimic (T412A) did. These results indicate that the constitutive turnover of phosphorylation at Thr-412 of p57/coronin-1 regulates its interaction with actin. 相似文献
992.
993.
Dimitri A. Svistunenko 《BBA》2005,1707(1):127-155
The reaction between hydroperoxides and the haem group of proteins and enzymes is important for the function of many enzymes but has also been implicated in a number of pathological conditions where oxygen binding proteins interact with hydrogen peroxide or other peroxides. The haem group in the oxidized Fe3+ (ferric) state reacts with hydroperoxides with a formation of the Fe4+=O (oxoferryl) haem state and a free radical primarily located on the π-system of the haem. The radical is then transferred to an amino acid residue of the protein and undergoes further transfer and transformation processes. The free radicals formed in this reaction are reviewed for a number of proteins and enzymes. Their previously published EPR spectra are analysed in a comparative way. The radicals directly detected in most systems are tyrosyl radicals and the peroxyl radicals formed on tryptophan and possibly cysteine. The locations of the radicals in the proteins have been reported as follows: Tyr133 in soybean leghaemoglobin; αTyr42, αTrp14, βTrp15, βCys93, (αTyr24−αHis20), all in the α- and β-subunits of human haemoglobin; Tyr103, Tyr151 and Trp14 in sperm whale myoglobin; Tyr103, Tyr146 and Trp14 in horse myoglobin; Trp14, Tyr103 and Cys110 in human Mb. The sequence of events leading to radical formation, transformation and transfer, both intra- and intermolecularly, is considered. The free radicals induced by peroxides in the enzymes are reviewed. Those include: lignin peroxidase, cytochrome c peroxidase, cytochrome c oxidase, turnip isoperoxidase 7, bovine catalase, two isoforms of prostaglandin H synthase, Mycobacterium tuberculosis and Synechocystis PCC6803 catalase-peroxidases. 相似文献
994.
This study examined the impact of ceramide, an intracellular mediator of apoptosis, on the mitochondria to test the hypothesis
that ceramide utilized p38 MAPK in the mitochondria to alter mitochondrial potential and induce apoptosis. The capacity of
ceramide to adversely affect mitochondria was demonstrated by the significant loss of mitochondrial potential (ΔΨm), indicated by a J-aggregate fluorescent probe, after embryonic chick cardiomyocytes were treated with the cell permeable
ceramide analogue C2-ceramide. p38 MAPK was identified in the mitochondrial fraction of the cell and p38 MAPK phosphorylation in this mitochondrial
fraction of the cell occurred with ceramide treatment. In addition, SAPK phosphorylation and a decrease in ERK phosphorylation
occurred in whole cell lysates after ceramide treatment. The p38 MAPK inhibitor SB 202190 but not the MEK inhibitor PD 98059
significantly inhibited ceramide-induced apoptosis and loss of ΔΨm. These data suggest that p38 MAPK is present in the mitochondria and its activation by ceramide indicates local signaling
more directly coupled to the mitochondrial pathway in apoptosis. (Mol Cell Biochem 278: 39–51, 2005) 相似文献
995.
Basma H El-Refaey H Sgagias MK Cowan KH Luo X Cheng PW 《Journal of biomedical science》2005,12(6):999-1011
Summary Chemotherapy has been used for treatment of breast cancer but with limited success. We characterized the effects of bcl-2
antisense and cisplatin combination therapy in two human isogenic breast carcinoma cells p53(+)MCF-7 and p53(−)MCF-7/E6. The
transferrin-facilitated lipofection strategy we have developed yielded same transfection efficiency in both cells. Bcl-2 antisense
delivered with this strategy significantly induced more cell death, apoptosis, and cytochrome c release in MCF-7/E6 than in MCF-7, but did not affect Fas level in both cells and activated caspase-8 equally. Cisplatin
exerted same effects on cell viability and apoptosis in both cells, but released smaller amounts of cytochrome c while activated more caspase-8 in MCF-7/E6. The combination treatment yielded greater effects on cell viability, apoptosis,
cytochrome c release, and caspase-8 activation than individual treatments in both cells although p53(−) cells were more sensitive. The
potentiated activation of caspase-8 in the combination treatment suggested that caspase-8-mediated (but cytochrome c-independent) apoptotic pathway is the major contributor of the enhanced cell killing. Thus, bcl-2 antisense delivered with
transferrin-facilitated lipofection can achieve the efficacy of killing breast cancer cells and sensitizing them to chemotherapy.
Bcl-2 antisense and cisplatin combination treatment is a potentially useful therapeutic strategy for breast cancer irrespective
of p53 status.
Hesham Basma and Hesham El-Refaey contributed equally 相似文献
996.
M.?I.?RajokaEmail author Amber?Yasmeen 《World journal of microbiology & biotechnology》2005,21(4):471-478
Summary Wild-type cultures of Aspergillus niger produced a basal level of β-fructofuranosidase on glucose of 1 IU l−1 h−1. In contrast, a catabolite-derepressed mutant strain of the same organism produced a markedly higher level (25 IU l−1 h−1) of this enzyme when grown on the same carbon source. Wheat bran induced both the wild type (252 IU l−1 h−1) and the mutant strain (516 IU l−1 h−1) to produce 252- to 516-fold higher levels of this enzyme than was observed with the wild-type grown on glucose and was the best carbon source. When corn steep liquor served as a nitrogen source, the wild-type organism showed a higher activity of enzyme on monosaccharides and disaccharides comparable to that produced by corncobs in the basal medium and that mutant was a potentially improved (> 2-fold) organism for the production of β-fructofuranosidase on all carbon sources. Enhanced substrate consumption and product formation kinetic parameters suggest that the mutant organism may be exploited for bulk production of this useful enzyme. 相似文献
997.
998.
999.
Attoumbré J Charlet S Baltora-Rosset S Hano C Raynaud-Le Grandic S Gillet F Bensaddek L Mesnard F Fliniaux MA 《Plant cell reports》2006,25(8):859-864
As flaxseed mainly accumulates lignans (secoisolariciresinol diglucoside and matairesinol), these compounds were barely or not detected in plant cell suspensions initiated from Linum usitatissimum. In contrast, these cell suspensions were shown to accumulate substantial amounts of a neolignan identified as dehydrodiconiferyl alcohol-4-β-d-glucoside (DCG) (up to 47.7 mg g−1 DW). The formation of this pharmacologically active compound was evaluated as a function of cell growth and in relation to phytohormone balance of the culture media. After establishment of efficient culture conditions, production of DCG was investigated in immobilized plant cell suspensions initiated from plantlet roots of L. usitatissimum. The results indicate that immobilization enhances the DCG production up to 60.0 mg g−1 DW but depresses the cell growth resulting in no improvement of the total DCG yield. Nevertheless, with immobilized cell suspensions, a release of DCG into the medium is observed allowing an easier recovery. 相似文献
1000.