Establishment of neurogenic microenvironment in the neurovascular unit: the connexin 43 story.

Connexins (Cx) play an important role in the coordination of intercellular communication, and autocrine and paracrine regulation of cells within the neurovascular unit (NVU). Gap junctional mechanisms control proliferation and differentiation processes underlying neurogenesis and angiogenesis in the brain. Cx43 possesses some unique properties [the ability to form either intercellular channels permeable for regulatory molecules and ions or hemichannels open to the extracellular space to provide release of cell metabolites; functional coupling with nicotinamide adenine dinucleotide (NAD+)-consuming and NAD+-dependent enzymatic processes] which may be of great importance for the fate of the stem cells. Dynamic changes in Cx43 expression are associated with different stages of brain cells development either at embryonic or adult periods of ontogenesis. This review summarizes recent data on Cx43-controlled neurogenesis in the context of NVU development and functioning. Understanding the molecular mechanisms of gap junctional intercellular communication will support translational studies focused on the development of regeneration-based approaches for the therapy of central nervous system pathology.