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Fibronectin gene expression in proliferating, quiescent, and SV40-infected mouse kidney cells
E W Khandjian1, C Salomon, N Léonard
1Département de Biochimie, Faculté de Médecine, Université Laval et Unité de Recherche en Génétique Humaine et Moléculaire, Hôpital St-François d'Assise, Québec, Canada.
Abstract:
To study alterations in cellular gene expression in mouse kidney cell cultures infected with simian virus 40 (SV40) or polyomavirus, we performed a differential screening of a mouse kidney cDNA library with probes prepared from mRNAs of virus-infected and mock-infected cells. We isolated and characterized cDNA recombinant pKT13 which detected increased mRNA levels in infected cells. Sequence analysis of pKT13 revealed close to 100% homology with the 3'-end of mouse fibronectin (FN) mRNA. Since primary cultures of baby mouse kidney cells have been extensively characterized in our laboratories, we studied FN gene expression at different stages of uninfected and virus-infected cultures. High levels of FN and of its mRNA were found in the kidneys of suckling mice, while in primary cultures of proliferating epithelial kidney cells the expression of FN was very low until the cultures became confluent. Thereafter FN increased and reached high levels in cells which were irreversibly arrested in phase Go and which had apparently exhausted their finite division potential. Infection of confluent cultures with polyomavirus or SV40 resulted in a further stimulation of FN gene expression. However, during abortive infection with SV40, FN mRNA and FN levels decreased with emergence of transformed cells and were low in an established SV40-transformed mouse kidney cell line. These changes in FN gene expression suggest that high levels of FN might be indicative in vivo for terminal differentiation and in vitro for cellular senescence.
Insights
Simian virus 40 (SV40) and polyomavirus infection alters cellular gene expression. Fibronectin (FN) gene expression increases with cellular senescence in vitro and terminal differentiation in vivo.
Area of Science:
- Molecular Biology
- Virology
- Cell Biology
Background:
- Cellular gene expression changes during viral infections.
- Fibronectin (FN) is a key extracellular matrix protein involved in cell adhesion and differentiation.
Purpose of the Study:
- To investigate alterations in mouse kidney cell gene expression upon infection with simian virus 40 (SV40) or polyomavirus.
- To characterize the role of fibronectin (FN) gene expression in cellular differentiation and senescence in kidney cells.
Main Methods:
- Differential screening of a mouse kidney cDNA library using mRNA from virus-infected and mock-infected cells.
- Isolation and characterization of cDNA recombinant pKT13, identifying it as mouse fibronectin (FN) mRNA.
- Analysis of FN gene expression in uninfected and virus-infected primary mouse kidney cell cultures at different stages.
Main Results:
- Isolated cDNA pKT13 showed high homology to mouse fibronectin (FN) mRNA, detecting increased mRNA levels in infected cells.
- FN and its mRNA levels were high in suckling mice kidneys, low in proliferating kidney cell cultures, and increased in confluent, senescent cells.
- Polyomavirus and SV40 infection further stimulated FN gene expression in confluent cultures; however, SV40 abortive infection led to decreased FN levels in transformed cells.
Conclusions:
- Increased fibronectin (FN) gene expression correlates with terminal differentiation in vivo and cellular senescence in vitro.
- Viral infections can modulate FN gene expression, with distinct effects observed during productive versus abortive infections and in transformed cells.