Determination of the role of cell to extracellular matrix interactions on apoptosis in Bufo viridis tail during metamorphosis

Anuran metamorphosis is one of the most interesting biological phenomenons. Metamorphosis, which is started and continued with single hormone action, takes place quite short time. Larvae undergo dramatic changes needed to adopt terrestrial andcarnivore life from aquatic and herbivore life during metamorphosis. Forming of new organs include mainly cell proliferation and differentiation necessary for adult life.Elimination of larval organs, which is not necessary for adult life, occurs via apoptosis. There are two models were argued for explaining cell death in regressing tail. The first oneis suicide model which suggests that cells commit to death by intrinsic pathway to respond of hormone; the latter one is murder model which suggests that cells killed by other cells orby losing their connections between extracellular matrix. In this study, relationship between cell to extracellular matrix interactions to apoptosis were tried to determine in tailduring spontaneously occurring and thyroid hormone induced metamorphosis of Bufo viridis larvae using TUNEL, immunohistochemistry and immunoblotting techniques. Forthis purpose, antibodies specific for integrin beta 1 which has important role in cell to extracellular matrix connection; type IV collagen which is one of the extracellular ligandsof integrin beta 1 and matrix metalloproteinase 1 which has role of degradation of both of these molecules selected. Additionally, apoptosis determination methods TUNEL andactive caspase 3 immunohistochemistry were compared. It was seen that especially matrix metalloproteinase 1 amount in the muscle tissue was increased onset of metamorphic climax and coincides with collagen IV degradation. Integrin beta 1 labeling was increased in apoptotic cells, was determined. Also, while determining the cells in early stages ofapoptosis, caspase 3 immunohistochemistry was more appropriate, determining the cells in late stages of apoptosis, TUNEL was more appropriate, was seen. It was seen that death of muscle cells begin in early stages of metamorphic climax and continue for regressionperiod of the tail. Our results suggest that cell death in muscle tissue derived from disruption of cell to extracellular matrix adhesion. Cells commit to die individually in epithelium was seen. Detecting molecules of Integrin/focal adhesion kinase pathway by immunohistochemical and immunoblotting methods or in vivo by marking withfluorescence dyes might be useful to clarify the process.