Cell polarity, asymmetric distribution of cellular components

Cell polarity is a conserved evolutionary process found in most organisms, and is essential for many functions of cells and tissues including the initial establishment and subsequent maintenance of epithelial tissues, asymmetric cell division, cell motility, cell differentiation, morphogenetic movements, and tissue repair.

It is characterized by the asymmetric distribution of cellular proteins, membranes, organelles and processes within the cell. The regulation of this process is very important for cell function, and cells use various mechanisms to ensure appropriate abundance and activity of polarity determinants ^(1,2,,3,4).

The members of these complexes function as protein magnets through their ability to bind or repel polarising organelles, cytoplasmic structures, cytoskeletal components, and cell fate determinant proteins ^(2,4). This complexes can facilitate either stable polarized states leading to specialized functional areas in tissues and organs, or adaptive polarization occurring, for example, during wound healing or immune cell responses ⁽¹⁾.

The localization and activity of polarity proteins is strongly regulated through kinases and phosphatases ⁽²⁾.

Polarity of cell is crucial during embryogenesis, and for maintenance of tissue architecture and homeostasis, wound healing, immune responses ...
This active process is triggered and maintained by extracellular signals transmitted by neighboring cells and/or the surrounding microenvironment. Even stably polarized tissues, such as the epithelium, must maintain polarization signals to control the transition between mesenchymal and epithelial states and vice versa.
Extracellular signals for the cellular polarity process are translated into a tightly regulated cascade of events that, if altered, can lead to disease states, including developmental abnormalities or tumorigenesis ⁽¹⁾.

The polarity of cell is closely related to cell proliferation and growth. Accordingly, many cellular polarity determinants have suppressive or pro-oncogenic properties and have been reported to be poorly regulated in a variety of different tumors, particularly those of epithelial origin ^(2,4).