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Detection of In Situ Protein-protein Complexes at the Drosophila Larval Neuromuscular Junction Using Proximity Ligation Assay
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POSH, a scaffold protein for JNK signaling, binds to ALG-2 and ALIX in Drosophila

Manabu Tsuda1, Ki-Hyeon Seong, Toshiro Aigaki

  • 1Department of Biological Sciences, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan.

FEBS Letters
|May 16, 2006
PubMed

Insights

Plenty of SH3s (POSH) interacts with Apoptosis-linked gene-2 (ALG-2) and ALG-2-interacting protein (ALIX) to regulate the Jun N-terminal kinase (JNK) pathway. This interaction influences cell death and developmental phenotypes in Drosophila eye development.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Developmental Biology

Background:

  • Plenty of SH3s (POSH) is a known scaffold protein in the Jun N-terminal kinase (JNK) signaling pathway.
  • The JNK pathway is implicated in cellular processes including cell death in mammalian cells and Drosophila.

Purpose of the Study:

  • To investigate the interaction of POSH with other proteins in the context of the JNK pathway.
  • To determine the role of POSH, Apoptosis-linked gene-2 (ALG-2), and ALG-2-interacting protein (ALIX/AIP1) in Drosophila eye development.

Main Methods:

  • Co-immunoprecipitation to assess protein complex formation.
  • Overexpression studies in Drosophila imaginal eye discs.
  • Analysis of developmental phenotypes (eye morphology).
  • Assessment of JNK pathway activation.

Main Results:

  • POSH forms a calcium-dependent complex with ALG-2 and ALIX.
  • Overexpression of ALG-2 or ALIX in Drosophila eye discs caused roughened or melanized eyes, respectively.
  • Co-overexpression of POSH with ALG-2 or ALIX enhanced these eye phenotypes.
  • Overexpression of ALG-2 or ALIX induced ectopic JNK activation.

Conclusions:

  • POSH, ALG-2, and ALIX form a functional complex.
  • This complex plays a role in regulating the JNK pathway.
  • The POSH/ALG-2/ALIX complex is involved in Drosophila eye development and JNK-mediated processes.

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