The sulfoxide of thymosin β4 almost lacks the polymerization‐inhibiting capacity for actin

Heintz, Daniela; Reichert, Andreas S.; Mihelic-Rapp, M.; Stoeva, Stanka; Voelter, Wolfgang; Faulstich, Heinz

doi:10.1111/j.1432-1033.1994.tb19000.x

Cited by 18 publications

(16 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Consistent with the latter hypothesis, S-thiolation of actin has been shown in association with respiratory bursts (27), and the sulfoxide isoform of the most abundant actin sequestering protein in mammalian cells, thymosin-␤4, is unable to sequester actin monomers (28).…”

Section: Discussionmentioning

confidence: 58%

Superoxide-mediated Actin Response in Post-hypoxic Endothelial Cells

Crawford¹,

Milliken²,

Irani³

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

The mechanism leading to changes in the superstructure of endothelial cells exposed to ischemia and reperfusion remains uncharacterized. We show that in posthypoxic endothelial cells, the simple re-addition of oxygen induces a profound reorganization of the actin cytoskeleton. The total filamentous actin pool increases by 41% and translocation of actin filaments to the submembranous network is observed. Concurrent with the actin polymerization, increased tyrosine phosphorylation of endothelial cell substrates is detected on Western blots. Overexpression of superoxide dismutase using replication incompetent adenovirus inhibits the actin and tyrosine phosphorylation responses to reoxygenation. Inhibition of tyrosine kinases with the isoflavone genistein also suppressed the actin polymerization response to reoxygenation, but unlike superoxide dismutase, genistein also induced the collapse of the superstructure of endothelial cells upon reoxygenation. These experiments support the concept that reoxygenation following a period of hypoxia can induce the remodeling of the actin cytoskeleton in endothelial cells. Such a response requires the intact coupling of superoxide producing pathway(s) with tyrosine kinase pathway(s).Angiogenesis can either rescue ischemic tissues by re-establishing an appropriate blood supply, or neovascularize proliferating tissues such as developing organs and neoplastic lesions (1, 2). Substantial progress has been made in the characterization of growth factors that promote or antagonize the angiogenic response (1-3). Vascular endothelial growth factor has been shown to be produced by the cells of ischemic tissues (glioblastoma and lung) (4, 5), and the receptors for vascular endothelial growth factor (flt and KDR) are up-regulated on the surface of endothelial cells in these tissues (4 -7). However, little is known about the molecular control of the cellular machinery (the actin cytoskeleton) that mediates the translocation of endothelial cells to ischemic areas, a process that is necessary, although not sufficient, for angiogenesis to take place.The vascular endothelial growth factor receptor, like most growth factor receptors, is a receptor tyrosine kinase (8 -10), whose signaling cascade is mediated by the clustering of effector molecules through the binding of SH2 domains to tyrosinephosphorylated residues. We found out recently that, in addition to tyrosine phosphorylation, the activity of growth factor receptors is also coupled to the production of reactive oxygen species (ROS) 1 such as superoxide or hydrogen peroxide (H 2 O 2 ) (11). Thus, activation of rat vascular smooth muscle cells with platelet-derived growth factor (PDGF) leads to H 2 O 2 production. Catalase or ROS chelators block the tyrosine kinase and mitogenic response to platelet-derived growth factor (11). Moreover, while ROS have been recognized in the past as mediators of intercellular interactions, we and others have recently identified ROS as major intracellular signal transduction messengers used by several small GTP...

show abstract

Section: Discussionmentioning

confidence: 58%

Superoxide-mediated Actin Response in Post-hypoxic Endothelial Cells

Crawford¹,

Milliken²,

Irani³

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Specifically, the modifications in the T␤ 4 molecule, such as oxidation at the Met-6 residue, as well as the alternative splicing variant containing an extra 6 or 7 aa and more methionines at the N-terminal, enhance its immunosuppressive functions (24). Considering that this sulfoxidation can abolish T␤ 4 actin-binding capacity, these findings may hint to the potential functional separation of T␤ 4 G-actinsequestering and immunosuppressive properties (69).…”

Section: Discussionmentioning

confidence: 99%

Thymosin β₄inhibits TNF‐α‐induced NF‐κB activation, IL‐8 expression, and the sensitizing effects by its partners PINCH‐1 and ILK

Qiu¹,

Wheater²,

Qiu³

et al. 2011

FASEB j.

View full text Add to dashboard Cite

The mechanisms by which thymosin β 4 (Tβ(4)) regulates the inflammatory response to injury are poorly understood. Previously, we demonstrated that ectopic Tβ(4) treatment inhibits injury-induced proinflammatory cytokine and chemokine production. We have also shown that Tβ(4) suppresses TNF-α-mediated NF-κB activation. Herein, we present novel evidence that Tβ(4) directly targets the NF-κB RelA/p65 subunit. We find that enforced expression of Tβ(4) interferes with TNF-α-mediated NF-κB activation, as well as downstream IL-8 gene transcription. These activities are independent of the G-actin-binding properties of Tβ(4). Tβ(4) blocks RelA/p65 nuclear translocation and targeting to the cognate κB site in the proximal region of the IL-8 gene promoter. Tβ(4) also inhibits the sensitizing effects of its intracellular binding partners, PINCH-1 and ILK, on NF-κB activity after TNF-α stimulation. The identification of a functional regulatory role by Tβ(4) and the focal adhesion proteins PINCH-1 and ILK on NF-κB activity in this study opens a new window for scientific exploration of how Tβ(4) modulates inflammation. In addition, the results of this study serve as a foundation for developing Tβ(4) as a new anti-inflammatory therapy.

show abstract

“…However, as 9utlined above, the presence of DNase I caused an only slight ~etardation in the reaction kinetics. In one particular case the affinity of a I]-thymosin for actin ¢¢as found to be greatly decreased under polymerization conditions [26]. We therefore examined whether salt would affect the formation of the ternary complex.…”

Section: Resultsmentioning

confidence: 99%

The ternary complex of DNase I, actin and thymosin β4

et al. 1996

Self Cite

View full text Add to dashboard Cite

Key words: Actin; Thymosin 134; DNase I; Ternary complex; Thiol-specific crosslinking the differently positioned thiol groups in TIM come close enough to distinct thiol groups in actin to allow the formation of crosslinks. In this way two contact sites between the two proteins could be identified, one between the C-terminus of actin (Cys 374) and position 6 of TIM and a second between the )'-phosphate of the actin-bound nucleotide in actin and the sequence 17 28 in TIM.X-ray analysis of monomeric actin took advantage of a facilitated crystallization of actin when complexed with DNase I. Provided DNase I exerted a similar effect on TIMactin as well, co-crystallization with DNase I would allow the interface of actin and TIM in the ternary complex to be studied. Corresponding complexes have been reported for DNase I, actin and profilin, or ADF/cofilin, respectively [14,15]. However, the ternary complex can be expected to form only if the binding of DNase I and that of TIM to actin do not strongly interfere. We therefore examined whether DNase I affects the affinity of TIM for actin by studying one of the crosslinking reactions mentioned above in the presence of DNase I. Materials and methods In~oductionThymosin 134 (TIM) is one of the small proteins in nonmuscle cells that bind to monomeric actin and thus prevent unregulated polymerization [14]. From the TiM-complexed monomers, polymerization can be started in vitro either by decapping barbed ends of filaments [5,6], or by adding nucleus stabilizers such as myosin S1 or phalloidin [7][8][9][10][11]. The relatively low affinity of T~4 for actin (ca. 1 ~tM [4]) may be functionally significant in allowing the instant release of polymerizable actin into cytoplasm, if required.Since an X-ray analysis of the actin-TiM complex has so far not been achieved we have tried to identify contact sites between the two proteins by a chemical approach [12]. For this, five TIM analogs were synthesized, each of them with one cysteine residue substituted for a hydrophobic amino acid in the TIM chain. Using a set of thiol-specific crosslinkers of varying length, we assayed whether in the complex with actin

show abstract

The sulfoxide of thymosin β4 almost lacks the polymerization‐inhibiting capacity for actin

Cited by 18 publications

References 34 publications

Superoxide-mediated Actin Response in Post-hypoxic Endothelial Cells

Superoxide-mediated Actin Response in Post-hypoxic Endothelial Cells

Thymosin β₄inhibits TNF‐α‐induced NF‐κB activation, IL‐8 expression, and the sensitizing effects by its partners PINCH‐1 and ILK

The ternary complex of DNase I, actin and thymosin β4

Contact Info

Product

Resources

About

The sulfoxide of thymosin β4 almost lacks the polymerization‐inhibiting capacity for actin

Cited by 18 publications

References 34 publications

Superoxide-mediated Actin Response in Post-hypoxic Endothelial Cells

Superoxide-mediated Actin Response in Post-hypoxic Endothelial Cells

Thymosin β4inhibits TNF‐α‐induced NF‐κB activation, IL‐8 expression, and the sensitizing effects by its partners PINCH‐1 and ILK

The ternary complex of DNase I, actin and thymosin β4

Contact Info

Product

Resources

About

Thymosin β₄inhibits TNF‐α‐induced NF‐κB activation, IL‐8 expression, and the sensitizing effects by its partners PINCH‐1 and ILK