TNC and GJA1 Are Putative Progenitor Markers That Are Localized in the Perivascular Adventitia of the Adult Monkey Brain Subventricular Niche

The largest area in the adult mammalian brain that contains stem and progenitor cells at different stages of differentiation is the subventricular zone located along the lateral wall of the lateral ventricle. We have previously shown in adult monkeys that transient global cerebral ischemia upregulates the expression of hundreds of genes in this zone, including genes known to be related to stemness in the rodent brain. Here, we analyzed the immunophenotype of two of these genes, <i>TNC</i> and <i>GJA1</i>, by co-expression experiments, applying a panel of known stem/progenitor-cell-related markers. We found that both <i>TNC</i> and <i>GJA1</i> were expressed in the perivascular region. They were localized not to the endothelial cells but to the periendothelial adventitial cells, which was consistent with our previous electron-microscopic data suggesting periendothelial cells as a source of progenitors. We report that the expression of <i>GJA1</i> was high in quiescent progenitors, while <i>TNC</i> was mostly present in progenitors in the transition from a quiescent to an active state. Our data suggest that <i>TNC</i> and <i>GJA1</i> can be used as markers for stem/progenitor cells in the largest stem cell area of the adult primate brain.