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Multiple tissues express alpha 1-antitrypsin in transgenic mice and man
J A Carlson1, B B Rogers, R N Sifers
1Department of Gastroenterology, Baylor College of Medicine, Houston, Texas 77030.
The Journal of Clinical Investigation
|July 1, 1988
Summary
Alpha 1-antitrypsin (AAT) is synthesized in various tissues, not just the liver. This suggests AAT has broader physiological roles beyond protecting the lungs from protease damage.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Hepatocytes are the primary source of alpha 1-antitrypsin (AAT), a key plasma antiprotease.
- AAT deficiency is linked to emphysema and liver disease, but the mechanism of hepatic injury is unclear.
- Previous studies showed AAT in various tissues of transgenic mice, but local synthesis versus endocytosis remained unresolved.
Purpose of the Study:
- To investigate the local synthesis of alpha 1-antitrypsin (AAT) in nonhepatic tissues.
- To determine if AAT is produced in various cell types beyond hepatocytes.
- To explore the broader physiological functions of AAT.
Main Methods:
- Utilized transgenic mice expressing the normal human AAT gene.
- Employed immunoelectron microscopy to detect AAT.
- Analyzed AAT mRNA presence in different tissues.
Main Results:
- AAT mRNA was detected in multiple tissues of the transgenic mouse.
- Immunoelectron microscopy revealed AAT within the rough endoplasmic reticulum of renal tubular and small intestinal epithelial cells.
- These findings indicate local AAT synthesis in these nonhepatic cell types.
Conclusions:
- The study supports the hypothesis of local alpha 1-antitrypsin (AAT) synthesis in various tissues.
- Beyond lung protection, AAT may play crucial physiological roles in other organs.
- This challenges the traditional view of AAT's function and origin.