UPTAKE OF TETRAPHENYLPORPHYCENE AND ITS PHOTOEFFECTS ON ACTIN AND CYTOKERATIN ELEMENTS OF HELA-CELLS

In the present work we have continued our studies in the photobiologic al properties of the 2,7,12,17-tetraphenylporphycene (TPPo). In partic ular, the uptake, the subcellular localization and the photoeffects on two cytoskeletal elements (actin, microfilaments and cytokeratin inte rmediate filaments) of HeLa cells have been analyzed. The uptake kinet ics of TPPo, determined by fluorescence spectroscopy, was initially ve ry rapid, reaching saturation at similar to 6 h of incubation. This po rphycene tends to be accumulated mainly in rounded particles distribut ed throughout the cytoplasm. The morphological comparison of the local ization pattern of TPPo and those of acridine orange and rhodamine 123 , which are fluorescence markers for lysosomes and mitochondria respec tively, allowed us to confirm that this porphycene is mainly accumulat ed in lysosomal organelles. The results obtained after treatment with TPPo and red light indicated that this compound is very effective in m ediating the photodestruction of lysosomes. The photosensitizing effec ts on the cytoskeletal elements studied depended on both the irradiati on time and the elapsed time after treatment. The implications of dama ge to lysosomes and actin and cytokeratin filaments on the process of cell death is discussed.