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Effects of polymorphonuclear neutrophils on protein synthesis by alkali-injured rabbit corneas. A preliminary study
Abstract:
Invasion of polymorphonuclear neutrophils (PMN) into injured cornea is one of the early events in corneal wound-healing. In the present studies, we examine the mutual effects on protein synthesis by PMN and injured and normal corneas when they are cocultured. PMN were labeled with [35S]methionine in the presence or absence of normal or alkali-injured rabbit corneas for 1-5 h. The acid-insoluble 35S-labeled proteins in medium, cells, and tissues were measured. Our data indicate that alkali-injured rabbit corneas induce higher rates of incorporation of [35S]methionine and secretion of 35S-labeled newly synthesized proteins by PMN. The newly synthesized 35S-labeled proteins were then analyzed by two-dimensional PAGE. The results indicate that alkali-injured and normal rabbit corneas enhance the synthesis and secretion of a 18-kD protein by PMN. In contrast, alkali injury greatly reduced the secretion of a group of proteins having molecular weights of approximately 30 kD by rabbit corneas. The alkali-injured corneas synthesize a new 200-kD protein (AC-200) in tissues and increase the secretion of a 120-kD protein (AC-120) into the culture medium. Furthermore, PMN slightly inhibits the incorporation of [35S]methionine and alter the synthesis of several 35S-labeled proteins by normal and injured corneas. For example, incubation with PMN abolishes the synthesis of the AC-200 protein, but enhances the secretion of the AC-120 protein by the alkali-injured corneas. However, the function and nature of these proteins remain largely unknown. Further studies are needed to elucidate the biological roles of these polypeptides during corneal wound healing.
Insights
Corneal injury alters protein synthesis in both polymorphonuclear neutrophils (PMN) and corneal tissues. Injured corneas stimulate PMN protein synthesis, while PMN influence corneal protein secretion during wound healing.
Area of Science:
- Ophthalmology
- Cell Biology
- Wound Healing Research
Background:
- Polymorphonuclear neutrophils (PMN) infiltrate injured corneas as an early step in corneal wound healing.
- Understanding the molecular crosstalk between PMN and corneal tissue is crucial for elucidating wound healing mechanisms.
Purpose of the Study:
- To investigate the mutual effects of PMN and normal or alkali-injured rabbit corneas on protein synthesis.
- To identify specific proteins synthesized or secreted by PMN and corneal tissues during this interaction.
Main Methods:
- PMN were labeled with [35S]methionine and co-cultured with normal or alkali-injured rabbit corneas for 1-5 hours.
- Quantification of acid-insoluble 35S-labeled proteins in medium, cells, and tissues.
- Analysis of newly synthesized proteins using two-dimensional polyacrylamide gel electrophoresis (PAGE).
Main Results:
- Alkali-injured corneas significantly increased [35S]methionine incorporation and secretion of newly synthesized proteins by PMN.
- Both normal and injured corneas enhanced PMN synthesis and secretion of an 18-kD protein.
- Alkali injury reduced secretion of ~30-kD proteins by corneas, but induced a new 200-kD protein (AC-200) and increased secretion of a 120-kD protein (AC-120).
- PMN inhibited corneal protein synthesis, abolished AC-200 synthesis, and enhanced AC-120 secretion in injured corneas.
Conclusions:
- Corneal injury and PMN presence dynamically alter protein synthesis and secretion profiles in both cell types.
- Specific proteins (e.g., AC-200, AC-120) are differentially regulated in injured corneas.
- The precise biological roles of these identified proteins in corneal wound healing require further investigation.