The Glioma-associated Protein SETA Interacts with AIP1/Alix and ALG-2 and Modulates Apoptosis in Astrocytes

Baihua Chen,Scott C Borinstein,Jennifer Gillis,Virginia W Sykes,Oliver Bogler

doi:10.1074/jbc.m908994199

Baihua Chen, Scott C Borinstein + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m908994199

Copy DOI

Abstract

Expression of the src homology 3 (SH3) domain-containing expressed in tumorigenic astrocytes (SETA) gene is associated with the tumorigenic state in astrocytes. SETA encodes a variety of adapter proteins containing either one or two SH3 domains, as suggested by the sequence heterogeneity of isolated cDNAs. Using both SH3 domains in a yeast two-hybrid screen of a glial progenitor cell cDNA library, we isolated the rat homolog of the ALG-2-interacting protein 1 or ALG-2-interacting protein X (AIP1/Alix). In vitro confrontation experiments showed that the SH3-N domain of SETA interacted with the proline-rich C terminus of AIP1. In co-immunoprecipitation experiments, SETA and AIP1 interacted and could form a complex with apoptosis-linked gene 2 protein. Endogenous SETA and AIP1 proteins showed similar patterns of staining in primary rat astrocytes. Misexpression of a variety of SETA protein isoforms in these astrocytes revealed that they localized to the actin cytoskeleton. Furthermore, SETA proteins containing the SH3-N domain were able to sensitize astrocytes to apoptosis induced by UV irradiation. Expression of the isolated SH3-N domain had the greatest effect in these experiments, indicating that interference in the interaction between endogenous SETA and AIP1 sensitizes astrocytes to apoptosis in response to DNA damage.

Highlights

The src homology 3 (SH3)[1] domain-containing expressed in tumorigenic astrocytes (SETA) gene was isolated from differentiating glial cells and implicated in primary brain tumors on the basis of its expression in malignant astrocytes in culture and gliomas in the adult brain in vivo (1)
The partial rat cDNA clone isolated by us (Fig. 1) was only one amino acid shorter than the mouse cDNA isolated by yeast two-hybrid screening with apoptosis-linked gene 2 (ALG-2) (7), suggesting that the same region of AIP1 interacts with both ALG-2 and SETA
Expression of SETA in cultured mouse p53Ϫ/Ϫ astrocytes and in astrocytes in the adult brain is associated with the tumorigenic state (1), suggesting that it may contribute to the process of glioma formation

Summary

Introduction

The src homology 3 (SH3)[1] domain-containing expressed in tumorigenic astrocytes (SETA) gene was isolated from differentiating glial cells and implicated in primary brain tumors on the basis of its expression in malignant astrocytes in culture and gliomas in the adult brain in vivo (1). Expression of the isolated SH3-N domain had the greatest effect in these experiments, indicating that interference in the interaction between endogenous SETA and AIP1 sensitizes astrocytes to apoptosis in response to DNA damage.

Results

Conclusion