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Domain requirements for an endocytosis-independent, isoform-specific function of dynamin-2

Fabienne Soulet1, Sandra L Schmid, Hanna Damke

  • 1Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

Experimental Cell Research
|August 30, 2006
PubMed

Insights

Dynamin-2 has a unique function beyond endocytosis: activating caspase-3 to cause apoptosis. This dynamin-2 specific function is independent of its endocytic role and is linked to its GTPase domain.

Area of Science:

  • Cell biology
  • Molecular biology
  • Biochemistry

Background:

  • Endocytosis relies on dynamin proteins, with dynamin-1 and dynamin-2 isoforms.
  • Overexpression of dynamin mutants can inhibit endocytosis by interfering with endogenous dynamin-2.
  • Dynamin-2 exhibits functions beyond endocytosis, but their structural basis is unclear.

Purpose of the Study:

  • To investigate the structural requirements for dynamin-2's isoform-specific function in activating caspase-3.
  • To differentiate endocytosis-dependent and -independent functions of dynamin isoforms.

Main Methods:

  • Utilized dynamin-2/dynamin-1 chimera proteins to map functional domains.
  • Introduced assembly-defective mutations in the GTPase Effector Domain (GED).
  • Assessed caspase-3 activation as a readout for dynamin-2 specific function.

Main Results:

  • Swapping the GTPase domain from dynamin-2 into dynamin-1 conferred caspase-3 activating ability.
  • Assembly-defective mutations in GED enhanced caspase-3 activation, independent of endocytosis.
  • Identified the GTPase domain as critical for dynamin-2's apoptosis-inducing function.

Conclusions:

  • Dynamin-2 possesses a distinct, endocytosis-independent function in triggering apoptosis via caspase-3 activation.
  • The GTPase domain is crucial for this specific dynamin-2 function.
  • Findings necessitate careful interpretation of dynamin-2 phenotypes in overexpression studies.

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