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Relationships between mesangial cell proliferation and types I and IV collagen mRNA levels in vitro
C J He1, L J Striker, M Tsokos
1Renal Cell Biology Section, National Institute of Diabetes and Digestive and Kidney Disease, National Cancer Institute, Bethesda, Maryland 20892, USA.
Abstract:
Changes in the composition of the mesangial extracellular matrix (ECM) and cell turnover are present in glomerular disease. To determine if ECM changes play a role in perpetuating mesangial cell dysfunction, we examined a line of mouse mesangial cells cultured on films or gels of several ECM components and also on methyl cellulose, an inert substrate that prevents attachment. Cells on films of fibronectin or type IV or I collagen had persistently high growth rates and high levels of alpha 1-I and alpha 1-IV collagen mRNAs. In contrast, on gels of type IV or I collagen or matrigel, the growth rate was low. The alpha 1-IV collagen mRNA levels were low on type IV collagen gel or matrigel, whereas the alpha 1-I collagen mRNA levels remained high. In contrast, the alpha 1-I collagen mRNA levels were low on type I collagen gel, and the alpha 1-IV collagen mRNA levels were high. Cells on methyl cellulose formed floating aggregates, did not proliferate, and had a 5- to 10-fold decrease in both alpha 1-I and alpha 1-IV collagen mRNA levels. These phenotypic changes were largely reversible. Finally, when matrigel was layered over cells on fibronectin films, alpha 1-IV collagen mRNA levels decreased, but alpha 1-I collagen mRNA levels and proliferation remained high. Thus proliferation and alpha 1-I and alpha 1-IV collagen mRNA levels in mesangial cells were independently regulated and depended on attachment and the nature of the adjacent matrix.
Insights
Extracellular matrix (ECM) components influence mesangial cell proliferation and collagen production. Mesangial cells cultured on different ECM substrates show varied responses, indicating independent regulation of cell growth and matrix synthesis.
Area of Science:
- Nephrology
- Cell Biology
- Biochemistry
Background:
- Glomerular diseases involve alterations in mesangial extracellular matrix (ECM) composition and cell turnover.
- The role of ECM changes in persistent mesangial cell dysfunction remains unclear.
Purpose of the Study:
- To investigate how different ECM components affect mesangial cell proliferation and collagen gene expression.
- To determine if ECM interactions regulate mesangial cell dysfunction.
Main Methods:
- Culturing mouse mesangial cells on various ECM substrates (fibronectin, type I collagen, type IV collagen, matrigel) and methyl cellulose.
- Measuring cell proliferation rates and alpha 1-I and alpha 1-IV collagen mRNA levels.
Main Results:
- Cells on fibronectin or collagen films exhibited high proliferation and collagen mRNA levels.
- Cells on collagen gels or matrigel showed reduced proliferation, with differential regulation of collagen mRNA.
- Non-adherent cells on methyl cellulose had significantly decreased proliferation and collagen mRNA levels.
- Phenotypic changes were largely reversible, and matrix layering demonstrated independent regulation of proliferation and collagen synthesis.
Conclusions:
- Mesangial cell proliferation and collagen mRNA levels are independently regulated.
- Cellular responses are dependent on substrate attachment and the specific nature of the adjacent extracellular matrix.