ИСТИНА

Myosin 1C is a monomeric motor protein belonging to the class I unconventional myosins. It plays key roles in modulating membrane tension, vesicle transport, tethering and secretion, as well as regulating transcription and chromatin remodeling in the nucleus. Furthermore, myosin 1C has been implicated in tumor progression, particularly in prostate cancer. Despite its significance in various cellular processes and potential prognostic value, the precise subcellular localization of myosin 1C remains poorly characterized. Clarifying its distribution is crucial for understanding the mechanisms of myosin 1C function in both normal and tumor cells. In this study, we investigated the localization of myosin 1C using immunohistochemistry on human prostate tissue sections. Myosin 1C was also visualized by high-resolution confocal microscopy in RWPE-1 (normal prostate epithelial) and PC-3 (prostate cancer) cell lines. Histological analysis revealed that myosin 1C is present in the ductal and acinar epithelial cells of the prostate gland, exhibiting an asymmetrical distribution within the cells, with accumulation predominantly at the luminal side. Quantitative analysis of subcellular localization in RWPE-1 and PC-3 cells demonstrated that, during interphase, myosin 1C preferentially localizes to active lamellar ruffles and the substrate-free regions of the plasma membrane. During mitosis, myosin 1C remains associated with the plasma membrane, showing minimal presence in the cytoplasm and an absence on chromosomes. Additionally, we analyzed the colocalization of myosin 1C with β- and γ- isoforms of cytoplasmic actin. In conclusion, our findings not only quantitatively confirm previously published data but also describe new patterns of myosin 1C localization in human prostate tissue and cell models under normal conditions and during tumor progression.