Dataset Information

Identification and characterization of multiple similar ligand-binding repeats in filamin: implication on filamin-mediated receptor clustering and cross-talk.

ABSTRACT: The actin-binding protein filamin links membrane receptors to the underlying cytoskeleton. The cytoplasmic domains of these membrane receptors have been shown to bind to various filamin immunoglobulin repeats. Notably, among 24 human filamin repeats, repeat 17 was reported to specifically bind to platelet receptor glycoprotein Ibalpha and repeat 21 to integrins. However, a complete sequence alignment of all 24 human filamin repeats reveals that repeats 17 and 21 actually belong to a distinct filamin repeat subgroup (containing repeats 4, 9, 12, 17, 19, 21, and 23) that shares a conserved ligand-binding site. Using isothermal calorimetry and NMR analyses, we show that all repeats in this subgroup can actually bind glycoprotein Ibalpha, integrins, and a cytoskeleton regulator migfilin in similar manners. These data provide a new view on the ligand specificity of the filamin repeats. They also suggest a multiple ligand binding mechanism where similar repeats within a filamin monomer may promote receptor clustering or receptor cross-talking for regulation of the cytoskeleton organization and diverse filamin-mediated cellular activities.

SUBMITTER: Ithychanda SS

PROVIDER: S-EPMC2787372 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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Identification and characterization of multiple similar ligand-binding repeats in filamin: implication on filamin-mediated receptor clustering and cross-talk.

Ithychanda Sujay Subbayya SS Hsu Dennis D Li Hanhan H Yan Linda L Liu David D DD Das Mitali M Plow Edward F EF Qin Jun J

The Journal of biological chemistry 20091014 50

The actin-binding protein filamin links membrane receptors to the underlying cytoskeleton. The cytoplasmic domains of these membrane receptors have been shown to bind to various filamin immunoglobulin repeats. Notably, among 24 human filamin repeats, repeat 17 was reported to specifically bind to platelet receptor glycoprotein Ibalpha and repeat 21 to integrins. However, a complete sequence alignment of all 24 human filamin repeats reveals that repeats 17 and 21 actually belong to a distinct fil ...[more]

PMID: 19828450

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Project description:Circular RNAs (circRNAs) have emerged as a new type of endogenous non-coding RNA characterized by their covalently closed circular structure and a backspliced junction (BSJ) resulting from a back-splicing process. In the last years, several studies have shown that circRNAs are important modulators in the immune system, activation of inflammation, antibacterial and antiviral responses as well as autoimmune diseases, such as multiple sclerosis. In the last years, it has been proposed that a subset of circRNA form imperfect double-stranded structures that allow them to interact with PKR (double stranded RNA-activated protein kinase), an intracellular protein responsible for recognizing long double stranded RNAs, usually viral RNAs, in the cytoplasm and trigger an anti-viral response of the cell. Taking into account the implication of the innate immune response in multiple sclerosis pathophysiology and the discovery of circRNA deregulation in multiple sclerosis patients, we wanted to investigate the circRNA-PKR crosstalk and its implication in the pathology of multiple sclerosis. Using an in vitro model of the anti-viral response and RNA-seq to characterize circRNA expression, we observed that poly (I:C) (a double-stranded RNA) stimulation produces a global downregulation of circRNA, PKR phosphorylation and immune-related gene activation and that these effects are reversed when treatment is stopped. Additionally, we found that the overexpression of double stranded RNA-containing circRNAs is able to reduce the PKR phosphorylation and the activation of immune-related pathways induced by poly(I:C). Finally, we measured the PKR phosphorylation in PBMCs isolated from multiple sclerosis patients in relapse and remission phases, but we did not obtain conclusive results since there is a very big variability between samples. In conclusion, this work reinforces the evidence on the mechanism describing the interaction between PKR and circRNA containing double-stranded structures and their role in the immune response. Besides, our experiments highlight the importance of the structure in circRNA function. Lastly, it also sheds some light into the possible implication of the circRNA-PKR axis in multiple sclerosis although further research is needed to make a better characterization of this mechanism in order to understand its potential role in the regulation of the immune response of the disease.

Dataset Information

Identification and characterization of multiple similar ligand-binding repeats in filamin: implication on filamin-mediated receptor clustering and cross-talk.

Publications

Identification and characterization of multiple similar ligand-binding repeats in filamin: implication on filamin-mediated receptor clustering and cross-talk.

Similar Datasets

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