makropinocytózy

Makropinocytóza is a form of endocytóza, a cellular process where the cell membrane engulfs fluid and solutes from the extracellular environment. This process is characterized by the formation of large, actin-dependent membrane extensions called macropinosomes. Unlike phagocytosis, which is involved in engulfing large solid particles, or receptor-mediated endocytosis, which is highly specific, makropinocytóza is a less specific, non-internalizing process that captures a broad range of extracellular material. It is a fundamental mechanism for cellular uptake and plays crucial roles in various biological functions.

The mechanism of makropinocytóza involves the dynamic remodeling of the actin cytoskeleton. Triggered by certain extracellular stimuli, such as growth factors or chemoattractants, the cell membrane initiates a process of protrusion and engulfment. This results in the formation of large vesicles, the macropinosomes, which contain a significant volume of extracellular fluid. Once formed, these macropinosomes typically fuse with early endosomes and their contents are processed, often leading to degradation or recycling of components.

Makropinocytóza is essential for a variety of cellular and physiological processes. It is involved in nutrient uptake, particularly in cells that lack specialized transport mechanisms. It also plays a role in immune surveillance, where professional antigen-presenting cells, like dendritic cells and macrophages, use makropinocytóza to sample their surroundings for antigens. Furthermore, makropinocytóza is implicated in tissue development, cell migration, and the regulation of cell volume. Dysregulation of makropinocytóza has been associated with various diseases, including cancer and infectious diseases, highlighting its broad biological significance.