splitGFP Technology Reveals Dose-Dependent ER-Mitochondria Interface Modulation by α-Synuclein A53T and A30P Mutants

Area of Science:

• Neuroscience
• Cell Biology
• Genetics

Background:

• Familial Parkinson's disease (PD) is linked to alpha-synuclein (α-syn) gene mutations.
• α-syn modulates the endoplasmic reticulum (ER)-mitochondria interface and calcium (Ca2+) handling.
• The impact of PD-related α-syn mutations on ER-mitochondria tethering remains unclear.

Purpose of the Study:

• Investigate how PD-related α-syn mutations (A53T, A30P) affect ER-mitochondria tethering and Ca2+ handling.
• Clarify the role of α-syn in ER-mitochondria connectivity in PD pathogenesis.
• Determine if mutations compromise α-syn's function at the ER-mitochondria interface.

Main Methods:

• Utilized a novel SPLICS sensor to assess ER-mitochondria connectivity.
• Employed aequorin-based measurements for mitochondrial Ca2+ transients.
• Introduced TAT-delivered A53T and A30P α-syn mutants into cells.

Main Results:

• A53T and A30P mutations did not inherently disrupt α-syn's ability to enhance ER/mitochondria tethering or Ca2+ transients.
• High concentrations of TAT-delivered A53T and A30P α-syn mutants led to α-syn redistribution from cytoplasm to foci.
• This redistribution resulted in a loss of α-syn's function in modulating ER-mitochondria tethering and Ca2+ handling.

Conclusions:

• PD-related α-syn mutations may act via a loss-of-function mechanism.
• Impaired ER-mitochondria Ca2+ cross-talk is potentially linked to PD pathogenesis.
• Findings highlight the importance of α-syn's cellular localization for its function.