Pax6 controls centriole maturation in cortical progenitors through Odf2

Abstract

Cortical glutamatergic neurons are generated by radial glial cells (RGCs), specified by the expression of transcription factor (TF) Pax6, in the germinative zones of the dorsal telencephalon. Here, we demonstrate that Pax6 regulates the structural assembly of the interphase centrosomes. In the cortex of the Pax6-deficient Small eye (Sey/Sey) mutant, we find a defect of the appendages of the mother centrioles, indicating incomplete centrosome maturation. Consequently, RGCs fail to generate primary cilia, and instead of staying in the germinative zone for renewal, RGCs detach from the ventricular surface thus affecting the interkinetic nuclear migration and they exit prematurely from mitosis. Mechanistically, we show that TF Pax6 directly regulates the activity of the Odf2 gene encoding for the appendage-specific protein Odf2 with a role for the assembly of mother centriole. Our findings demonstrate a molecular mechanism that explains important characteristics of the centrosome disassembly and malfunctioning in developing cortex lacking Pax6.

ODF2 maintains centrosome cohesion by restricting β-catenin accumulation

“…ODF2 not only defines the old centrosome but is also responsible for microtubule stability. Depletion of ODF2 thus disturbs asymmetric cell division, resulting in a depletion of the stem cell pool during neurogenesis (Wang et al, 2009;Tylkowski et al, 2014;Gasic et al, 2015;Hung et al, 2016). The preimplantation lethality observed in ODF2-deficient mice may therefore be caused by perturbing replenishing of the stem cell pool (Salmon et al, 2006).…”

“…At 24 h before siRNA transfection cells, were initially transfected with an expression plasmid encoding Centrin2-GFP to highlight centrosomes. Short hairpin constructs sh3 (specifically targeting the sequence GAACTCCTCCAGGAGATAC of mouse ODF2; Tylkowski et al, 2014) or K07 (Origene), which functions as a control since homology to any known mRNA is missing, and the expression plasmids encoding human cenexin (hCenexin) (Soung et al, 2006), human centrin 2 fused to Cherry (Centrin2-Cherry), and histone H2A fused to Emerald (Addgene #54110) were transfected with Lipofectamin 2000 (ThermoFisher Scientific Biosciences). Eg5-inhibitor VS-83 was used at a final concentration of 5 µM for 2 h (Millipore-Calbiochem).…”

Primary cilia in corneal development and disease

“…Therefore, cilia also play an important role in regulating the expression of inflammatory mediators, and cilium-related molecules may be used as diagnostic indicators in the treatment of dry eye. In contrast, transcription factor paired box 6 (PAX6) is down-regulated in dry eye, which can regulate the activity of outer dense fiber 2 (ODF2), a centrosomal protein, and participate in the assembly of mother centrioles ( Chen et al, 2013 ; Tylkowski et al, 2015 ).…”

Neuron's little helper: The role of primary cilia in neurogenesis

“…Interestingly, in Pax6-deficient radial glial cells, cilia reassembly is impaired and cells prematurely exit the cell cycle to generate postmitotic differentiating neurons. 19 On the other hand, not only formation but also timely reabsorption of primary cilia is important when cells are about to exit the cell cycle. Inhibiting the reabsorption of the primary cilium prior to mitosis in both cultured pluripotent stem cells and cortical neural progenitors again resulted in the premature exit from the cell cycle and the onset of neuronal differentiation.…”