LIPRIN-□ REGULATES SYNAPTIC ORGANIZATION BY INTERACTING AND LOCALIZING PROTEIN PHOSPHATASE 2A AT THE SYNAPTIC TERMINI
Document Type
Presentation
Start Date
22-10-2010 9:30 AM
End Date
22-10-2010 9:45 AM
Description
Purpose: Active zones (AZs) are presynaptic membrane domains that mediate vesicle fusion and transmitter release. At drosophila neuromuscular junctions (NMJ), cytoplasmic matrix of active zone proteins (CAZ), such as Liprin-□, play important role in synaptic assembly and maturation. We aim to identify novel Liprin-□ associated molecules, and their mode of function during synaptic development.
Methods: We first generated transgenic flies expressing C-terminal TAP tagged Liprin-□ in neuronal system. We then collected ~30,000 adult fly heads and performed tandem affinity purification to isolate the whole Liprin-□ associated protein complex. Liprin-□ binding partners were identified by shot-gun proteomics through LC-MS/MS. We then took genetic and cellular means to analyze the functions of Liprin-binding partners and their relationship to Liprin-□ during synaptic development.
Results: Many CAZ proteins are identified as Liprin-D binding partners, including BRP (CAST) and RIM. Here we report the interaction between protein phosphatase 2A (PP2A) and Liprin-□ and its importance in regulating synaptic organization. All three subunits of PP2A, the core subunit, the catalytic subunit (Mts) and the B' regulatory subunits (Wrd) are identified in the list. The interaction is further confirmed by Co-IP using either GFP or TAP tagged Liprin-□. PP2A are previously shown to regulate synaptogenesis. Here we demonstrate that Liprin-□ and wrd mutants show similar defects such as smaller synaptic size, abnormal BRP puncta and mis-apposition of pre-and post-synaptic density. Furthermore, the mis-apposition defect in Liprin-□ mutant is enhanced by removing one copy of wrd gene. Liprin-□ mutants also show axon transportation defect, however this defect is not enhanced by heterozygous wrd mutant. These data led us to hypothesize that the organizational roles of Liprin-□ is at least partially mediated by the interaction between Wrd/PP2A. In support of our hypothesis, we demonstrate that Liprin-□ is absolutely required for the synaptic localization of Wrd while Wrd is not required for Liprin-□ localization.
Conclusions: We purpose that one of the major roles of Liprin-□ is to localize PP2A to the synapse by specifically interacting with one of its regulatory subunits Wrd. The synaptic localization of PP2A is crucial for its function in regulating active zone maturation and synaptic morphogenesis.
Recommended Citation
Li, Long; Li, J.; Tian, X.; and Wu, C., "LIPRIN-□ REGULATES SYNAPTIC ORGANIZATION BY INTERACTING AND LOCALIZING PROTEIN PHOSPHATASE 2A AT THE SYNAPTIC TERMINI" (2010). Dr. Joseph M. Moerschbaecher, III Graduate Research Day. 5.
https://digitalscholar.lsuhsc.edu/grad_rs/2010/presentation1/5
LIPRIN-□ REGULATES SYNAPTIC ORGANIZATION BY INTERACTING AND LOCALIZING PROTEIN PHOSPHATASE 2A AT THE SYNAPTIC TERMINI
Purpose: Active zones (AZs) are presynaptic membrane domains that mediate vesicle fusion and transmitter release. At drosophila neuromuscular junctions (NMJ), cytoplasmic matrix of active zone proteins (CAZ), such as Liprin-□, play important role in synaptic assembly and maturation. We aim to identify novel Liprin-□ associated molecules, and their mode of function during synaptic development.
Methods: We first generated transgenic flies expressing C-terminal TAP tagged Liprin-□ in neuronal system. We then collected ~30,000 adult fly heads and performed tandem affinity purification to isolate the whole Liprin-□ associated protein complex. Liprin-□ binding partners were identified by shot-gun proteomics through LC-MS/MS. We then took genetic and cellular means to analyze the functions of Liprin-binding partners and their relationship to Liprin-□ during synaptic development.
Results: Many CAZ proteins are identified as Liprin-D binding partners, including BRP (CAST) and RIM. Here we report the interaction between protein phosphatase 2A (PP2A) and Liprin-□ and its importance in regulating synaptic organization. All three subunits of PP2A, the core subunit, the catalytic subunit (Mts) and the B' regulatory subunits (Wrd) are identified in the list. The interaction is further confirmed by Co-IP using either GFP or TAP tagged Liprin-□. PP2A are previously shown to regulate synaptogenesis. Here we demonstrate that Liprin-□ and wrd mutants show similar defects such as smaller synaptic size, abnormal BRP puncta and mis-apposition of pre-and post-synaptic density. Furthermore, the mis-apposition defect in Liprin-□ mutant is enhanced by removing one copy of wrd gene. Liprin-□ mutants also show axon transportation defect, however this defect is not enhanced by heterozygous wrd mutant. These data led us to hypothesize that the organizational roles of Liprin-□ is at least partially mediated by the interaction between Wrd/PP2A. In support of our hypothesis, we demonstrate that Liprin-□ is absolutely required for the synaptic localization of Wrd while Wrd is not required for Liprin-□ localization.
Conclusions: We purpose that one of the major roles of Liprin-□ is to localize PP2A to the synapse by specifically interacting with one of its regulatory subunits Wrd. The synaptic localization of PP2A is crucial for its function in regulating active zone maturation and synaptic morphogenesis.