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Fibronectin gene expression in polymorphonuclear leukocytes. Accumulation of mRNA in inflammatory cells
Abstract:
Using a fibronectin cDNA probe, we have studied the accumulation of fibronectin mRNA in polymorphonuclear leukocytes (PMN) in response to inflammation. Nonactivated PMN from human peripheral blood were used as a source of noninflammatory cells and PMN from inflamed knee joints of patients with chronic inflammatory joint disorders (rheumatoid and psoriatic arthritis) were used as a source of inflammatory cells. By dot blot and Northern hybridization analysis, we have found the presence of fibronectin mRNA in these cells. Its size was estimated at approximately equal to 8.7-8.8 kilobases. When noninflammatory PMN were compared to inflammatory PMN in terms of fibronectin mRNA accumulation, a marked increase was found in inflammatory cells (2- to 12.7-fold stimulation). It was also observed that the increased mRNA levels in inflammatory PMN lead to increased synthesis of the protein. These findings establish that PMN are part of the fibronectin-producing cells and that the level of mRNA in these cells is influenced by the inflammatory process.
Insights
Inflammation significantly increases fibronectin messenger RNA (mRNA) in polymorphonuclear leukocytes (PMN). These inflammatory cells show higher fibronectin mRNA levels, leading to increased protein synthesis.
Area of Science:
- Biochemistry
- Immunology
- Molecular Biology
Background:
- Fibronectin is a key extracellular matrix protein involved in cell adhesion and tissue repair.
- Polymorphonuclear leukocytes (PMN) are crucial immune cells involved in inflammatory responses.
- The role of PMN in fibronectin production during inflammation is not fully understood.
Purpose of the Study:
- To investigate the accumulation of fibronectin mRNA in human PMN during inflammation.
- To determine if inflammatory conditions modulate fibronectin mRNA levels in PMN.
- To assess the relationship between fibronectin mRNA levels and protein synthesis in PMN.
Main Methods:
- Utilized a fibronectin cDNA probe for molecular analysis.
- Employed dot blot and Northern hybridization techniques.
- Compared fibronectin mRNA levels in nonactivated PMN (peripheral blood) and inflammatory PMN (inflamed joints).
Main Results:
- Fibronectin mRNA was detected in both nonactivated and inflammatory PMN, with an approximate size of 8.7-8.8 kilobases.
- Inflammatory PMN exhibited a 2- to 12.7-fold increase in fibronectin mRNA accumulation compared to nonactivated PMN.
- Elevated fibronectin mRNA levels in inflammatory PMN correlated with increased fibronectin protein synthesis.
Conclusions:
- Human PMN are capable of producing fibronectin.
- The inflammatory process significantly upregulates fibronectin mRNA levels in PMN.
- PMN contribute to the fibronectin pool during inflammation, with their mRNA levels being dynamically regulated by the inflammatory state.