The distribution and function of alternatively spliced insertions in hDlg

Area of Science:

• Molecular and Cell Biology
• Protein Structure and Function
• Cancer Research

Background:

• hDlg, the human homolog of Drosophila Discs-large tumor suppressor, is a MAGUK family scaffolding protein.
• hDlg contains PDZ repeats, SH3 motif, and a GUK domain, with known alternative splicing regions.
• Understanding hDlg isoform diversity is crucial for its role in cellular processes and disease.

Purpose of the Study:

• To identify and characterize novel insertions and alternative splicing in the human discs-large (hDlg) protein.
• To analyze the tissue-specific expression of hDlg isoforms.
• To determine the functional impact of alternative splicing and insertions on hDlg protein localization and interactions.

Main Methods:

• Identification of a novel insertion (I1B) in the N-terminal region of hDlg.
• Analysis of tissue-specific combinations of insertions and alternative splicing.
• Functional studies to assess the role of alternatively spliced regions in protein binding and localization.

Main Results:

• A novel insertion, I1B, was identified N-terminal to the PDZ repeats.
• The N-terminal alternatively spliced region binds SH3 domains and modulates protein oligomerization.
• Insertions in the second region (I3 to cell membrane, I2 to nucleus) dictate hDlg localization.

Conclusions:

• Alternative splicing and novel insertions create diverse hDlg protein isoforms with distinct functions.
• Specific insertions (I2, I3) are key determinants of hDlg subcellular localization.
• These findings provide insights into the complex regulation and functional versatility of hDlg in human cells.