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13:08
Quantitative Localization of a Golgi Protein by Imaging Its Center of Fluorescence Mass
Published on: August 10, 2017
Nongenomic STAT5-dependent effects on Golgi apparatus and endoplasmic reticulum structure and function
Jason E Lee1, Yang-Ming Yang, Feng-Xia Liang
1Dept. of Cell Biology & Anatomy, New York Medical College, Valhalla, NY 10595, USA.
American Journal of Physiology. Cell Physiology
|December 14, 2011
Summary
Signal transducer and activator of transcription (STAT) 5 proteins unexpectedly maintain Golgi and endoplasmic reticulum (ER) structure in vascular cells. Their disruption causes organelle damage and nuclear changes, linked to pulmonary hypertension.
Area of Science:
- Cell Biology
- Molecular Biology
- Vascular Biology
Background:
- Signal transducer and activator of transcription (STAT) proteins are traditionally known for their roles in gene transcription.
- The non-genomic functions of STAT proteins, particularly in cytoplasmic organelle maintenance, remain largely unexplored.
- Vascular cell organelle integrity is crucial for vascular function and health.
Purpose of the Study:
- To investigate unexpected cytoplasmic functions of STAT5 proteins in vascular cells.
- To determine the role of STAT5 in maintaining the structure and function of the Golgi apparatus and endoplasmic reticulum (ER).
- To explore the potential link between STAT5-mediated organelle dysfunction and human diseases like idiopathic pulmonary hypertension.
Main Methods:
- Immunoimaging and green fluorescent protein (GFP)-tagged STAT5a localization studies in human pulmonary arterial endothelial and smooth muscle cells.
- Acute knockdown of STAT5a/b using small interfering RNAs (siRNAs), with and without mRNA synthesis inhibition.
- Analysis of ER/Golgi dynamics in STAT5a/b knockout mouse embryo fibroblasts and assessment of protein interactions (RTN4, ATL3).
Main Results:
- Constitutive association of nonphosphorylated STAT5a and STAT5b with the Golgi apparatus and STAT5a with centrosomes was observed.
- STAT5a/b knockdown induced dramatic Golgi fragmentation, ER tubule-to-cyst changes, nuclear membrane separation, nuclear distortion, and impaired protein trafficking and mitochondrial function.
- The observed phenotype mimicked cellular changes in arterial lesions of idiopathic pulmonary hypertension, with atlastin-3 (ATL3) binding to STAT5a/b.
Conclusions:
- STAT5 proteins have novel nongenomic functions essential for preserving Golgi and ER structure in vascular cells.
- STAT5-mediated organelle dysfunction, characterized by ER/Golgi changes and nuclear distortion, is implicated in the pathogenesis of idiopathic pulmonary hypertension.
- These findings reveal a new role for STAT proteins in cytoplasmic organelle regulation and disease.
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