Ror-family receptor tyrosine kinases regulate maintenance of neural progenitor cells in the developing neocortex

Abstract

SummaryThe Ror family receptor tyrosine kinases (RTKs), Ror1 and Ror2, have been shown to play crucial roles in developmental morphogenesis by acting as receptors or co-receptors to mediate Wnt5a-induced signaling. Although Ror1, Ror2 and Wnt5a are expressed in the developing brain, little is known about their roles in the neural development. Here we show that Ror1, Ror2 and their ligand Wnt5a are highly expressed in neocortical neural progenitor cells (NPCs). Small interfering RNA (siRNA)-mediated suppression of Ror1, Ror2 or Wnt5a in cultured NPCs isolated from embryonic neocortex results in the reduction of bIII-tubulin-positive neurons that are produced from NPCs possibly through the generation of T-box brain 2 (Tbr2)-positive intermediate progenitors. BrdU-labeling experiments further reveal that the proportion of proliferative and neurogenic NPCs, which are positive for neural progenitor cell marker (Pax6) but negative for glial cell marker (glial fibrillary acidic protein; GFAP), is reduced within a few days in culture following knockdown of these molecules, suggesting that Ror1, Ror2 and Wnt5a regulate neurogenesis through the maintenance of NPCs. Moreover, we show that Dishevelled 2 (Dvl2) is involved in Wnt5a-Ror1 and Wnt5a-Ror2 signaling in NPCs, and that suppressed expression of Dvl2 indeed reduces the proportion of proliferative and neurogenic NPCs. Interestingly, suppressed expression of either Ror1 or Ror2 in NPCs in the developing neocortex results in the precocious differentiation of NPCs into neurons, and their forced expression results in delayed differentiation. Collectively, these results indicate that Wnt5a-Ror1 and Wnt5a-Ror2 signaling pathways play roles in maintaining proliferative and neurogenic NPCs during neurogenesis of the developing neocortex.

Wnt Signaling Regulates Multipolar-to-Bipolar Transition of Migrating Neurons in the Cerebral Cortex

“…An important new observation of the present study is that Wnt5A/non-canonical signaling activity is critical for the transient downregulation of canonical Wnt signaling during the multipolar stage. Consistent with previous published reports (Endo et al, 2012), we found that the non-canonical ligand,Wnt5A is expressed in pyramidal precursor cells. Furthermore, we demonstrate that the expression level of Wnt5A is relatively low in the VZ but progressively increased as cells pass through the SVZ.…”

“…These observations support the hypothesis that time-dependent and pyramidal precursor-intrinsic regulation of Wnt5A/non-canonical signaling inhibits the canonical pathway, thereby allowing proper cell polarization. This hypothesis is consistent with previous observations that pyramidal precursors in the developing cortex express not only Wnt5A but also the non-canonical receptors Ror 1 and 2 (Endo et al, 2012). Intriguingly, a similar cell-intrinsic modulation of Wnt canonical as well as non-canonical signaling has been implicated in the control of neuroblast migration in C. elegans (Mentink et al, 2014), indicating that this regulatory mechanism, similarly to guidance by Wnt morphogenic gradient, is evolutionarily conserved.…”

Wingless-type Mammary Tumor Virus Integration Site Family, Member 5A (Wnt5a) Regulates Human Immunodeficiency Virus Type 1 (HIV-1) Envelope Glycoprotein 120 (gp120)-induced Expression of Pro-Inflammatory Cytokines via the Ca2+/Calmodulin-dependent Protein Kinase II (CaMKII) and c-Jun N-terminal Kinase (JNK) Signaling Pathways

“…Briefly, the neurons was cultured in 12-well plates coated with poly-D-lysine containing Neurobasal medium supplemented with 10% B27 and 0.5 mM L-glutamine for 10 -14 days before use. For siRNA transfection, Wnt5a siRNA (target sequence GCAGAUGUAGCCUGUAAGU) (42) and control nonmatching oligonucleotides were synthesized and transfected using GenMute siRNA Transfection Reagent (SignaGen Laboratories, Ijamsvile, MD) according to the manufacturer's instructions. Two days post-transfection, the cells were collected for analysis.…”

Role of Wnt5a-Ror2 Signaling in Morphogenesis of the Metanephric Mesenchyme during Ureteric Budding

“…Wnt5a-Ror2 signaling primarily regulates cell polarity and migration in a variety of cell types (1,(5)(6)(7)(8)(9)(10)(11). Wnt5a-Ror2 signaling also plays a crucial role in maintaining neural progenitor cells in a proliferative, undifferentiated state in the developing neocortex (12). During mouse development, Ror2 and Wnt5a are expressed in various tissues and organs in spatiotemporally similar manners (13)(14)(15).…”