The trans-golgi compartment: A new distinct intracellular Ca store
Paola Pizzo1, Valentina Lissandron, Tullio Pozzan
1Dept Biomedical Sciences; University of Padova and CNR Institute of Neuroscience; Padova, Italy.
Communicative & Integrative Biology
|November 9, 2010
Summary
The Golgi apparatus (GA) handles calcium (Ca2+) differently across its compartments. Targeting calcium in the trans-Golgi disrupts protein transport and GA structure.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The Golgi apparatus (GA) is crucial for protein and lipid modification and sorting.
- The GA participates in calcium (Ca2+) signaling, accumulating and releasing Ca2+ like the endoplasmic reticulum (ER).
- GA Ca2+ handling involves ATP-dependent enzymes: sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) and secretory pathway Ca2+ ATPase1 (SPCA1), and inositol 1,4,5-trisphosphate (IP3) receptors.
Purpose of the Study:
- To investigate the heterogeneity of Ca2+ handling within the Golgi apparatus.
- To determine the specific roles of SPCA1, SERCA, and IP3 receptors in different GA compartments.
- To elucidate the functional consequences of altered Ca2+ levels in the trans-Golgi.
Main Methods:
- Utilized a novel Förster Resonance Energy Transfer (FRET)-based Ca2+ probe targeted to the trans-Golgi.
- Employed RNA interference (RNAi) to selectively reduce SPCA1 levels.
- Observed effects on protein trafficking and Golgi morphology.
Main Results:
- Demonstrated Ca2+ handling heterogeneity within the GA.
- Found the trans-Golgi to be insensitive to IP3 and reliant on SPCA1 for Ca2+ accumulation.
- Identified SERCA and IP3 receptors as localized to cis- and intermediate GA compartments.
- Showed that reducing trans-Golgi Ca2+ via SPCA1 depletion severely impairs protein trafficking and causes Golgi collapse.
Conclusions:
- The Golgi apparatus exhibits distinct Ca2+ handling mechanisms across its cis, intermediate, and trans compartments.
- SPCA1 activity in the trans-Golgi is essential for maintaining Ca2+ homeostasis and proper protein trafficking.
- Disruption of trans-Golgi Ca2+ leads to significant defects in the secretory pathway and Golgi integrity.
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