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Protease inhibitors suppress the formation of tight junctions in gastrointestinal cell lines
A Bacher1, K Griebl, S Mackamul
1Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, Garching, Germany.
Abstract:
Tight junctions (TJ) of the fascia occludens type can be induced in the human colon adenocarcinoma cell lines HT29 and Caco-2 by treatment with 320 mM cesium sulfate. This process can be completely inhibited by the protease inhibitors leupeptin and antipain. The concentration for 50% inhibition was 32 microM leupeptin and 270 microM antipain, respectively. In the polarized colon carcinoma cell line Caco-2, the spontaneous formation of histotypical TJ and the development of transepithelial electrical resistance do not occur when the cells are cultured in medium containing 400 microM leupeptin. Following the removal of leupeptin, zonula occludens type TJ and electrical resistance develop synchronously during a period of 4 h. Dihydroleupeptin, the alcohol analog of leupeptin, inhibits neither the spontaneous nor the induced assembly of TJ fibrils. Thus, the aldehyde group of leupeptin is essential for activity. These data suggest that the salt-induced as well as the spontaneous formation of TJ involve cellular proteases which are susceptible to protease inhibitors.
Insights
Protease inhibitors like leupeptin block tight junction (TJ) formation in colon cancer cells. Inhibiting these proteases prevents TJ assembly, suggesting their crucial role in TJ development.
Area of Science:
- Cell Biology
- Molecular Biology
- Gastroenterology
Background:
- Tight junctions (TJ) are crucial for epithelial barrier function.
- Understanding TJ formation mechanisms is vital for treating diseases involving epithelial dysfunction.
Purpose of the Study:
- To investigate the role of cellular proteases in the formation of tight junctions.
- To determine the inhibitory effects of protease inhibitors on TJ assembly in colon cancer cell lines.
Main Methods:
- Induction of tight junctions using cesium sulfate in HT29 and Caco-2 cells.
- Inhibition studies using protease inhibitors leupeptin and antipain.
- Assessment of tight junction formation and transepithelial electrical resistance.
Main Results:
- Cesium sulfate induced tight junction formation, which was inhibited by leupeptin and antipain.
- Leupeptin at 400 microM prevented spontaneous TJ formation and electrical resistance development in Caco-2 cells.
- The aldehyde group of leupeptin was essential for its inhibitory activity on TJ assembly.
Conclusions:
- Cellular proteases are involved in both induced and spontaneous tight junction formation.
- Protease inhibitors offer a potential mechanism to modulate tight junction assembly.
- These findings highlight the significance of proteases in maintaining epithelial integrity.