Therefore, lysosomal positioning is crucial for PMR and cell invasion by some pathogens, as well as many other cellular mechanisms. amazonensis invasion to non-phagocytic cells, using basically the same mechanism previously described for T. Showed that lysosomal positioning is also crucial for L. cruzi enters cardiomyocytes, showed that depletion of membrane cholesterol led to a decrease in host cell invasion by interfering with lysosome recruitment and fusion during parasite-host cell interaction. cruzi, which subverts PMR mechanism to invade cells. Verified that the mobilization of lysosomes is a key event for effective cell infection by T. Some parasites, such as Trypanosoma cruzi and Leishmania amazonensis, can subvert PMR to invade different host cells ( The whole process involves the participation of lysosomal hydrolases, which act on the extracellular leaflet of the plasma membrane and facilitates the endocytic process by inducing plasma membrane invagination and its inward budding ( Lysosomal exocytosis is then followed by a massive endocytosis, which reseals the plasma membrane by carrying wounded portions in endosomes into the cell. Upon injury, extracellular Ca 2+ flows through the lesions into the cytoplasm, increasing cytoplasmic Ca 2+ concentration, which in turn induces lysosomal exocytosis. Briefly, when a cell suffers a micro-injury, its membrane must be sealed to avoid depolarization, cytoplasm leakage and cell death. One example is plasma membrane repair (PMR), a mechanism widely used by nucleated cells to maintain plasma membrane integrity. Mobilization of lysosome pools is described in several situations ( The authors further suggested that the change in the polymerization of actin filaments induced by cholesterol depletion could be compromising the mobilization of the slow releasing or reserve vesicles. However, the subsequent release of the remaining vesicles, belonging to the second slow-releasing pool, also called the reserve pool, was compromised by changes in membrane cholesterol levels. The authors observed that membrane cholesterol sequestration from chromaffin cells of the adrenal medulla did not alter either the kinetics or the amount of release of the first pool of vesicles, which was already pre-anchored to the plasma membrane. This was achieved by depolarization of the membrane, rearrangement of the actin filaments and dissolution of the cytoskeleton barrier, leading to its detachment from the cytoskeleton to reach the exocytic sites.Īlso provided evidence for the existence of different pools of secretory vesicles and that membrane cholesterol content is important for exocytosis of these pools. The first pool was located just below the plasma membrane and the secretion of this pool was not regulated by the cytoskeleton, but attached to the plasma membrane as a result of being bound to elements of the cytoskeleton the second pool was attached to actin filaments, slightly away from the membrane, which could be mobilized to the inner leaflet of the plasma membrane after the depletion of the first pool. In 1988, Aunis and Bader showed that two pools of secretory vesicles exist in secretory cells ( Aunis and Bader, 1988). For this reason, many studies have focused on the pathways that regulate the distribution of vesicles in both physiological and pathological conditions, while others have examined the consequences of aberrant vesicle distribution in many important cellular processes. Intracellular vesicles are important components of the endocytic and secretory pathways, which are responsible for maintaining several critical cellular functions. By tracking fluorescent vesicles based on their position relative to cell nuclei we are able to quantify and analyze their distribution throughout the cell. This protocol can be used widely within the scientific community because it utilizes ImageJ/FIJI, an open source software that is free. The method is an accessible way to analyze the density and dispersion of intracellular vesicles by combining immunofluorescence with pixel-based quantification software ( e.g., ImageJ/FIJI). The method presented here is a simple, affordable, and efficient tool to analyze the distribution of intracellular vesicles such as lysosomes, endosomes, Golgi vesicles or secretory granules under different experimental conditions. More specifically, the strategic distribution of intracellular vesicles is important for diverse cellular processes. Cell signalling, cell secretion, and plasma membrane repair are processes that critically rely on intracellular vesicles, important components of the endocytic and secretory pathways.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |