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

## TL;DR

This study identifies TNC and GJA1 as potential markers for stem/progenitor cells in the adult monkey brain's subventricular zone, located near blood vessels.

## Contribution

The paper introduces TNC and GJA1 as novel markers for progenitor cells in the adult primate brain's subventricular niche.

## Key findings

- TNC and GJA1 are expressed in the perivascular adventitia, not in endothelial cells.
- GJA1 is highly expressed in quiescent progenitors, while TNC is present in progenitors transitioning to an active state.
- TNC and GJA1 can serve as markers for stem/progenitor cells in the adult primate brain.

## Abstract

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, TNC and GJA1, by co-expression experiments, applying a panel of known stem/progenitor-cell-related markers. We found that both TNC and GJA1 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 GJA1 was high in quiescent progenitors, while TNC was mostly present in progenitors in the transition from a quiescent to an active state. Our data suggest that TNC and GJA1 can be used as markers for stem/progenitor cells in the largest stem cell area of the adult primate brain.