Phospholipase Cbeta1b associates with a Shank3 complex at the cardiac sarcolemma

Area of Science:

• Cardiovascular Biology
• Cell Signaling
• Molecular Cardiology

Background:

• G protein Gq activation induces cardiomyocyte hypertrophy.
• Phospholipase Cβ1b (PLCβ1b) is the key mediator of Gq signaling in cardiomyocytes.
• PLCβ1b's localization to the cardiac sarcolemma is essential for its function.

Purpose of the Study:

• To investigate the molecular mechanisms targeting PLCβ1b to the cardiac sarcolemma.
• To identify proteins interacting with PLCβ1b at the sarcolemma.
• To determine the role of sarcolemmal localization in PLC signaling and hypertrophy.

Main Methods:

• Co-immunoprecipitation assays to identify interacting proteins.
• Analysis of protein localization using subcellular fractionation and microscopy.
• Small interfering RNA (siRNA) knockdown to assess functional significance.

Main Results:

• PLCβ1b specifically co-immunoprecipitated with SH3 and ankyrin repeat protein 3 (Shank3) and α-fodrin.
• The C-terminal tail of PLCβ1b mediates its binding to Shank3 and α-fodrin.
• Shank3 and PLCβ1b colocalized at the sarcolemma, and Shank3 knockdown impaired PLC activation and hypertrophic responses.

Conclusions:

• PLCβ1b associates with a Shank3 complex at the cardiac sarcolemma through its splice-variant-specific C-terminal tail.
• Sarcolemmal localization of PLCβ1b, facilitated by Shank3, is critical for downstream signaling in Gq-coupled receptor activation.
• This mechanism underscores the importance of protein targeting for cardiomyocyte hypertrophy signaling.