Capillary electrophoretic analysis reveals subcellular binding between individual mitochondria and cytoskeleton.

Area of Science:

• Cell Biology
• Biophysics

Background:

• Cytoskeleton-mitochondria interactions are vital for cellular functions.
• Bulk analysis methods for these interactions are limited by assumptions of complete binding and fail to account for free subcellular components.

Purpose of the Study:

• To develop and apply capillary electrophoresis with dual laser induced fluorescence detection (CE-LIF) for individual analysis of mitochondria-cytoskeleton binding events.
• To quantify the proportion of mitochondria bound to the cytoskeleton and the amount of associated F-actin.

Main Methods:

• Fluorescent labeling of mitochondria (DsRed2) and F-actin (Alexa488-phalloidin).
• Utilizing CE-LIF to identify, classify, count, and quantify individual binding events.
• Employing electrophoretic mobility to differentiate bound from unbound mitochondria.

Main Results:

• CE-LIF demonstrated that 79% of mitochondrial events in L6 myoblasts lacked detectable F-actin.
• Bound mitochondria possessed approximately 2 zmol of F-actin per event, corresponding to a ~2.5 micrometer actin network.
• Trypsin treatment reduced the fraction of F-actin-associated mitochondria, validating the method's specificity.

Conclusions:

• CE-LIF offers a precise method to study individual mitochondria-cytoskeleton interactions, overcoming limitations of bulk analysis.
• The findings highlight that a significant majority of mitochondria are not bound to the cytoskeleton in typical cellular fractions.
• This technique has potential applications in studying drug effects, viral infections, and interactions with other cellular structures.