Identification and Dynamic Regulation of Tight Junction Protein Expression in Human Neural Stem Cells

Abstract

Recent reports indicate that neural stem cells (NSCs) exist in a cluster-like formation in close proximity to cerebral microvessels. Similar appearing clusters can be seen ex vivo in NSC cultures termed neurospheres. It is known that this neurosphere configuration is important for preserving stemness and a proliferative state. How NSCs form neurospheres or neuroclusters remains largely undetermined. In this study, we show that primary human NSCs express the tight junction proteins (TJPs): zonula occludens-1 (ZO-1), occludin, claudin-1, -3, -5, and -12. The relative mRNA expression was measured by quantitative polymerase chain reaction, and protein expression was confirmed by flow cytometry and immunofluorescence microscopy. Our results show that downregulation of TJPs occurs as neuronal differentiation is induced, suggesting that control of TJPs may be tied to the neuronal differentiation program. Importantly, upon specific knockdown of the accessory TJP, ZO-1, undifferentiated NSCs showed decreased levels of key stem cell markers. Taken together, our results indicate that TJPs possibly aid in maintaining the intercellular configuration of NSCs and that reduction in TJP expression consequently affects the stemness status.

Src Family Kinase Inhibitors and their Role in the Treatment of Traumatic Brain Injuries

“…PP1 was also associated with decreased edema, increased levels of the tight junction protein zonula occludens-1 (ZO-1), and decreased levels of vascular endothelial growth factor (VEGF) [49,50]. These studies indicate that the timing of SFK inhibitor treatment in TBI is critical; SFK inhibitor therapy immediately after TBI can potentially ameliorate cognitive dysfunction.…”

The blood brain barrier: Insights from development and ageing

“…63,64 Surprisingly, NSC maintenance appears to utilise TJ proteins expressed by the stem cells themselves. 97 Both within the brain and in ex vivo culture NSCs grow in clusters, termed neurospheres in cultures, which express a range of TJ proteins until the onset of differentiation. Knock down of ZO-1 alone was sufficient to initiate NSC differentiation within these neurospheres, revealing a novel function of TJ components in regulating stem cell identity, likely though preserving cell-cell contacts within the 3D structures.…”

Potential of Neural Stem Cell-Based Therapy for Parkinson’s Disease

“…The attachment of the BM to cells is primarily through laminins to sulfated glycolipids on the cell surface and transmembrane receptors [ 37 ]. The identification of dynamic regulation of tight junction proteins in human NSCs means that the cell-matrix interactions in the neurogenic niche, or potential target sites of NSC transplantation, will influence the therapeutic effects of NSCs in PD [ 38 ].…”