Dynamin1 long- and short-tail isoforms exploit distinct recruitment and spatial patterns to form endocytic...

Area of Science:

• Cell Biology
• Molecular Biology
• Biophysics

Background:

• Endocytosis is a vital cellular process requiring coordinated molecular interactions for membrane fission.
• The precise mechanisms by which cytosolic proteins like dynamin concentrate at specific plasma membrane sites are not fully understood.
• Dynamin-1, a key protein in endocytosis, exists in major splice variants differing in their C-terminal proline-rich region (short-tail vs. long-tail).

Purpose of the Study:

• To investigate the differential recruitment and nanoclustering behavior of short-tail (ab, bb) versus long-tail (aa) dynamin-1 isoforms at the plasma membrane.
• To elucidate the role of dynamin GTPase activity and Calcineurin in the formation and properties of dynamin-1 nanoclusters.
• To explore the spatiotemporal dynamics and search patterns of dynamin-1 isoforms during nanocluster generation using advanced modeling.

Main Methods:

• Single-particle tracking photoactivated localization microscopy (sptPALM) was employed in PC12 cells, neurons, and MEF cells.
• Activity-dependent recruitment and nanocluster formation of dynamin-1 isoforms were analyzed.
• Spatiotemporal modeling was utilized to simulate and confirm the search patterns and dimensional reduction processes.

Main Results:

• Short-tail dynamin-1 isoforms (ab, bb) exhibited activity-dependent recruitment to the membrane, followed by concentration into nanoclusters.
• These nanoclusters were sensitive to Calcineurin and dynamin GTPase inhibitors.
• Compared to the long-tail isoform (aa), short-tail isoforms formed larger, denser, and more numerous nanoclusters.
• Spatiotemporal modeling confirmed distinct search patterns for dynamin-1 isoforms, with short-tail variants more effectively utilizing lateral trapping.

Conclusions:

• Dynamin-1 splice variants exhibit distinct behaviors in membrane recruitment and nanocluster formation, influencing endocytic site organization.
• Short-tail dynamin-1 isoforms are more efficient in generating nanoclusters through mechanisms like lateral trapping.
• These findings provide insights into the regulation of endocytosis and the functional divergence of dynamin-1 splice variants.