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Dynamin 2 mutations associated with human diseases impair clathrin-mediated receptor endocytosis

Marc Bitoun1, Anne-Cécile Durieux, Bernard Prudhon

  • 1Institut National de la Santé et de la Recherche Médicale, U582, Institut de Myologie, Paris, France. m.bitoun@institut-myologie.org

Human Mutation
|July 23, 2009
PubMed

Insights

New dynamin 2 (DNM2) mutations in the GTPase effector domain cause centronuclear myopathy (CNM) by impairing endocytosis. This study reveals DNM2

Area of Science:

  • Molecular biology
  • Cell biology
  • Genetics

Background:

  • Dynamin 2 (DNM2) is a GTPase crucial for endocytosis and intracellular trafficking.
  • Mutations in DNM2's middle (MD) and Pleckstrin homology (PH) domains are linked to centronuclear myopathy (CNM) and Charcot-Marie-Tooth (CMT) neuropathy.
  • The GTPase effector domain (GED) role in DNM2-related diseases was previously unexplored.

Purpose of the Study:

  • To investigate the impact of a novel DNM2 mutation in the GTPase effector domain (GED) on cellular processes.
  • To determine if DNM2 mutations in different domains affect clathrin-mediated endocytosis.
  • To explore the consequences of DNM2 mutations on epidermal growth factor receptor (EGFR) signaling.

Main Methods:

  • Site-directed mutagenesis to create DNM2 constructs with mutations in MD, PH, and GED.
  • Transfection of COS7 cells and analysis of transferrin and low-density lipoprotein (LDL) uptake.
  • Assessment of clathrin-mediated endocytosis in patient-derived skin fibroblasts.
  • Measurement of extracellular signal-regulated kinase 1 (ERK1) and ERK2 activation following epidermal growth factor (EGF) stimulation.

Main Results:

  • A novel DNM2 mutation in the GED (p.E650K) was identified in a patient with slowly progressive myopathy.
  • DNM2 mutants in MD, PH, and GED domains reduced transferrin and LDL uptake in COS7 cells, indicating impaired clathrin-mediated endocytosis.
  • Impaired endocytosis was also observed in skin fibroblasts from a CNM patient.
  • Epidermal growth factor (EGF)-induced ERK1/2 activation was impaired in transfected COS7 cells but not in CNM fibroblasts.

Conclusions:

  • Impairment of clathrin-mediated endocytosis is a potential mechanism in DNM2-related diseases.
  • DNM2 mutations across different domains can disrupt endocytic pathways.
  • The tissue-specific effects of DNM2 mutations in CNM and CMT require further investigation.

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