Modulation of EGF receptor autophosphorylation by α‐hemolysin of <i>Staphylococcus aureus</i> via protein tyrosine phosphatase

Vandana, S.; Sangha, Navneet; Kaur, Surinder; Krishnasastry, M.V.

doi:10.1016/s0014-5793(02)03862-0

Cited by 8 publications

(5 citation statements)

References 27 publications

(35 reference statements)

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“…However, both p‐Tyr‐EGFR‐specific sandwich enzyme‐linked immunosorbant assay (ELISA) and immunoprecipitation with EGFR‐specific antibodies followed by Western blots with conventional phosphotyrosine‐specific antibodies failed to detect EGFR tyrosine phosphorylation in toxin‐treated cells (not shown). This was in accord with a previous report in which EGFR tyrosine phosphorylation was investigated in α‐toxin‐treated A431 cells (Vandana et al ., 2003). However, Western blot experiments with an antibody that specifically recognizes phosphotyrosine 1173 of the EGFR revealed that the receptor becomes phosphorylated at this site in toxin‐treated cells (Fig.…”

Section: Resultscontrasting

confidence: 56%

Pore-forming Staphylococcus aureus ?-toxin triggers epidermal growth factor receptor-dependent proliferation

et al. 2006

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Section: Resultscontrasting

confidence: 56%

Pore-forming Staphylococcus aureus ?-toxin triggers epidermal growth factor receptor-dependent proliferation

et al. 2006

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“…The proteins were transferred to a nitrocellulose membrane using 10 mM 3-[cyclohexylamino]-1-propanesulfonic acid buffer (pH 10.5) at 150 mA for 2 h. The blot was subjected to immunodetection with antiphosphotyrosine antibody. The cells treated with TGF␣ exhibited a slightly diffuse EGFr band because of their phosphorylation (Vandana et al 2003).…”

Section: Phosphorylation Of Egfr Erk P38 and Caveolin-1mentioning

confidence: 99%

Stress-induced phosphorylation of caveolin-1 and p38, and down-regulation of EGFr and ERK by the dietary lectin jacalin in two human carcinoma cell lines

2006

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We have examined the A431 (human epidermoid carcinoma) and HT29 (human colorectal carcinoma) cellular responses evoked by lectins of dietary origin, Jacalin of Artocarpus integrifolia (native jacalin; nJacalin), peanut agglutinin (PNA) of Arachis hypogea, and recombinant single-chain jacalin (rJacalin), which has the same protein backbone but approximately 100-fold less affinity for carbohydrates than nJacalin. All three lectins (nJacalin, rJacalin, and PNA) are cycotoxic inhibitors of proliferation of A431 cells. However, cells recover once jacalin but not PNA have been removed from the growth medium. Treatment of nJacalin results in morphologically visible cell rounding while retaining the membrane integrity when treated at 40 microg ml(-1), but treatment with PNA did not induce such changes. The observed cell rounding was found to be due to stress as the phosphorylation of caveolin-1 (at tyr14), p38 but not c-Jun N-terminal kinase were up-regulated, while PNA did not up-regulate the phosphorylation of the same. Jacalin also down-regulated the phosphorylation of the epidermal growth factor receptor and extracellular signal regulated kinase in contrast to PNA, which failed to down-regulate the same. Confocal microscopic studies reveal that jacalin is not internalized, unlike the lectin of Agaricus bisporous. Analysis of the proteins that bind to an nJacalin-sepharose column revealed the binding of six to eight proteins, and significant among them is a protein at approximately 110 kDa, which appears to be oxygen-regulated protein 150 (ORP150) (endoplasmic reticulum chaperone) as identified by its isoelectric point, two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometric analysis. This 110-kDa band is detectable with anti-Hsp70 antibody because ORP150 has homology with Hsp70. Confocal microscopic studies reveal the presence of Hsp70-like proteins on the surface of A431 cells as revealed by immunostaining with anti-Hsp70 antibody. Moreover, overexpression of ORP150 in A431 cells has resulted in a dramatic protection of A431 cells against jacalin-induced toxicity, confirming that the jacalin-induced cytotoxicity is mediated through ORP150, and impairment of ORP150 functions with the help of jacalin makes the cells more susceptible to death due to stress. Our studies suggest that the cellular responses, as a consequence of lectin binding, may not be exclusively mediated by carbohydrate binding property alone, but other factors such as protein-protein interactions may also contribute to the observed cellular responses.

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“…We have carried out the present study with the help of H35N mutant of α-HL, an oligomerization deficient mutant of the toxin. The H35N does not assemble beyond the membrane bound monomeric stage on target cells as it cannot form efficient inter-protomer interactions to form a pre-pore [8]. Earlier studies have shown that low doses of α-HL treatment of Jurkat T cells resulted in caspase activation via mitochondrial pathway and oligonucleosomal DNA fragmentation.…”

Section: Resultsmentioning

confidence: 99%

“…H35N) was constructed as described earlier [6]. α-HL and H35N were cloned and expressed in E. coli JM109(DE3) under the control of T7 promoter and purified as described earlier [7], [8].…”

Section: Methodsmentioning

confidence: 99%

Membrane Bound Monomer of Staphylococcal α-Hemolysin Induces Caspase Activation and Apoptotic Cell Death despite Initiation of Membrane Repair Pathway

et al. 2009

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BackgroundWild type Staphylococcal α-hemolysin (α-HL) assembly on target mammalian cells usually results in necrotic form of cell death; however, caspase activation also occurs. The pathways of caspase activation due to binding/partial assembly by α-HL are unknown till date.ResultsCells treated with H35N (a mutant of α-HL that remains as membrane bound monomer), have been shown to accumulate hypodiploid nuclei, activate caspases and induce intrinsic mitochondrial apoptotic pathway. We have earlier shown that the binding and assembly of α-HL requires functional form of Caveolin-1 which is an integral part of caveolae. In this report, we show that the caveolae of mammalian cells, which undergo a continuous cycle of ‘kiss and run’ dynamics with the plasma membrane, have become immobile upon the binding of the monomer. The cells treated with H35N were unable to recover despite activation of membrane repair mechanism involving caspase-1 dependent activation of sterol regulatory element binding protein-1.ConclusionsThis is for the first time we show the range of cellular changes and responses that take place immediately after the binding of the monomeric form of staphylococcal α-hemolysin.

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Modulation of EGF receptor autophosphorylation by α‐hemolysin of Staphylococcus aureus via protein tyrosine phosphatase

Cited by 8 publications

References 27 publications

Pore-forming Staphylococcus aureus ?-toxin triggers epidermal growth factor receptor-dependent proliferation

Pore-forming Staphylococcus aureus ?-toxin triggers epidermal growth factor receptor-dependent proliferation

Stress-induced phosphorylation of caveolin-1 and p38, and down-regulation of EGFr and ERK by the dietary lectin jacalin in two human carcinoma cell lines

Membrane Bound Monomer of Staphylococcal α-Hemolysin Induces Caspase Activation and Apoptotic Cell Death despite Initiation of Membrane Repair Pathway

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