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Tissue specific expression of alternatively spliced murine PECAM-1 isoforms
N Sheibani1, C M Sorenson, W A Frazier
1Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA. @biochem.wustl.edu
Summary
This study reveals multiple platelet endothelial cell adhesion molecule-1 (PECAM-1) isoforms in mouse tissues and endothelial cells. PECAM-1 isoform expression varies by tissue and is developmentally regulated, impacting cell interactions.
Area of Science:
- Molecular Biology
- Cell Biology
- Immunology
Background:
- Platelet endothelial cell adhesion molecule-1 (PECAM-1), also known as CD31, is a cell adhesion molecule crucial for endothelial cell-cell junctions.
- PECAM-1 exists in multiple isoforms generated by alternative splicing, differing in their cytoplasmic domains.
- The tissue-specific distribution of PECAM-1 isoforms has not been previously characterized.
Purpose of the Study:
- To investigate the tissue distribution of different PECAM-1 isoforms in various mouse tissues and endothelial cells.
- To identify novel PECAM-1 isoforms and determine their expression patterns.
- To understand the developmental regulation of PECAM-1 isoform expression.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT/PCR) was employed to analyze PECAM-1 mRNA expression in diverse mouse tissues and cultured endothelial cells.
- Cloning and sequencing of RT/PCR products were performed to identify specific PECAM-1 isoforms.
- Western blotting using antibodies against PECAM-1 extracellular domains and specific exon 14 was used to analyze protein expression.
Main Results:
- PECAM-1 mRNA was highly expressed in lung, heart, and kidney, with lower levels in brain and liver.
- Most cultured endothelial cells expressed high PECAM-1 mRNA, but normal mouse brain endothelial cells showed rapid loss of expression in culture.
- Multiple PECAM-1 isoforms were detected in various tissues and endothelial cells, with the isoform lacking exons 14 and 15 being most frequent. A novel isoform lacking exons 12 and 14 was found in brain.
- Western blot analysis revealed distinct PECAM-1 protein bands, and the absence of exon 14 in lower molecular weight forms indicated developmentally regulated expression.
Conclusions:
- Multiple PECAM-1 isoforms are expressed across different mouse tissues and endothelial cell types.
- The expression of PECAM-1 isoforms is developmentally regulated and varies significantly between tissues.
- Further research into PECAM-1 isoform distribution and interactions is essential for understanding its role in endothelial cell biology and morphogenesis.