Cellular and Molecular Characterization of Multipolar Map5-Expressing Cells: A Subset of Newly Generated, Stage-Specific Parenchymal Cells in the Mammalian Central Nervous System

Abstract

Although extremely interesting in adult neuro-glio-genesis and promising as an endogenous source for repair, parenchymal progenitors remain largely obscure in their identity and physiology, due to a scarce availability of stage-specific markers. What appears difficult is the distinction between real cell populations and various differentiation stages of the same population. Here we focused on a subset of multipolar, polydendrocyte-like cells (mMap5 cells) expressing the microtubule associated protein 5 (Map5), which is known to be present in most neurons. We characterized the morphology, phenotype, regional distribution, proliferative dynamics, and stage-specific marker expression of these cells in the rabbit and mouse CNS, also assessing their existence in other mammalian species. mMap5 cells were never found to co-express the Ng2 antigen. They appear to be a population of glial cells sharing features but also differences with Ng2+progenitor cells. We show that mMap5 cells are newly generated, postmitotic parenchymal elements of the oligodendroglial lineage, thus being a stage-specific population of polydendrocytes. Finally, we report that the number of mMap5 cells, although reduced within the brain of adult/old animals, can increase in neurodegenerative and traumatic conditions.

Pharmacological Properties and Biological Functions of the GPR17 Receptor, a Potential Target for Neuro-Regenerative Medicine

“…where NG2 has been downregulated and more advanced markers like O4, O1 and the proteolipid myelin protein PLP are present (Fumagalli et al 2011a). Based on these data, GPR17 is currently utilized by other independent scientists to specifically label pre-immature OLs at these two transition stages (Mitew et al 2013;Nakatani et al 2013;Crociara et al 2013;Ferrara et al 2016).…”

Noncanonical Sites of Adult Neurogenesis in the Mammalian Brain

“…They are also called synantocytes (Butt et al 2005) or polydendrocytes (Nishiyama et al 2009), and are morphologically, antigenically, and functionally distinct from mature astrocytes, oligodendrocytes, and microglia. NG stands for neuron-glia, and NG2 þ cells can express neuronal markers during differentiation (see Crociara et al 2013) leading to confusion and perhaps erroneous data interpretation in the literature. Despite their proliferative capacity and potentialities in vitro, NG2 þ cells do not contribute to neurogenesis in vivo (reviewed in Boda and Buffo 2010;Trotter et al 2010;Richardson et al 2011).…”

“…Despite their proliferative capacity and potentialities in vitro, NG2 þ cells do not contribute to neurogenesis in vivo (reviewed in Boda and Buffo 2010;Trotter et al 2010;Richardson et al 2011). Nevertheless, some of these cells are oligodendrocyte progenitor cells that generate oligodendrocytes in the mature CNS (Horner et al 2000;Dubois-Dalcq et al 2008;Crociara et al 2013) and may have multifaceted functions (e.g., neuromodulatory and neuroprotective functions, homeostatic regulations of synaptic functions) that remain to be further investigated (Boda and Buffo 2014).…”

MiR-125a-3p timely inhibits oligodendroglial maturation and is pathologically up-regulated in human multiple sclerosis

“…Of these, GPR17 is a new oligodendroglial marker expressed in early OPCs up to the stage of immature pre-oligodendrocytes 22 and now widely adopted to specifically label OPCs at an intermediate differentiation stage partially overlapping with O4 ( Fig. 3 ; refs 23 , 35 , 36 , 37 , 38 ). O4 is instead a well-established marker of immature oligodendrocytes 39 .…”