Cargo- and adaptor-specific mechanisms regulate clathrin-mediated endocytosis

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Clathrin-mediated endocytosis (CME) is a crucial cellular process for internalizing surface molecules.
• The heterogeneous dynamics of clathrin-coated pits (CCPs) suggest regulatory mechanisms, potentially involving cargo content.

Purpose of the Study:

• To investigate the impact of cargo content, specifically low-density lipoprotein receptor (LDLR) expression, on CCP size and dynamics.
• To elucidate the role of LDLR-specific adaptors, Dab2 and ARH, in mediating cargo-dependent CCP regulation.

Main Methods:

• Utilized live-cell imaging of fluorescently tagged proteins (Dab2-mCherry, ARH-mCherry) in cells with varying LDLR expression levels.
• Quantified CCP size, endocytic event duration, and maturation rates.

Main Results:

• Increased LDLR expression led to larger CCPs and non-terminal endocytic events in Dab2-expressing cells.
• In ARH-expressing cells, elevated LDLR levels increased abortive CCP turnover and decreased CCP maturation rates.
• Demonstrated a direct correlation between cargo load and CCP assembly dynamics.

Conclusions:

• CCP assembly is a highly dynamic process responsive to cargo composition.
• Cargo content, influenced by LDLR expression and adaptor proteins (Dab2, ARH), contributes significantly to the observed heterogeneity in CCP dynamics.