Molecular Memory of Morphologies by Septins during Neuron Generation Allows Early Polarity Inheritance

Abstract

Transmission of polarity established early during cell lineage history is emerging as a key process guiding cell differentiation. Highly polarized neurons provide a fascinating model to study inheritance of polarity over cell generations and across morphological transitions. Neural crest cells (NCCs) migrate to the dorsal root ganglia to generate neurons directly or after cell divisions in situ. Using live imaging of vertebrate embryo slices, we found that bipolar NCC progenitors lose their polarity, retracting their processes to round for division, but generate neurons with bipolar morphology by emitting processes from the same locations as the progenitor. Monitoring the dynamics of Septins, which play key roles in yeast polarity, indicates that Septin 7 tags process sites for re-initiation of process growth following mitosis. Interfering with Septins blocks this mechanism. Thus, Septins store polarity features during mitotic rounding so that daughters can reconstitute the initial progenitor polarity.

Polarity of Neuronal Membrane Traffic Requires Sorting of Kinesin Motor Cargo during Entry into Dendrites by a Microtubule-Associated Septin

“…In epithelial cells, septins associate with subsets of MTs and are required for vesicle transport from the Golgi complex to the plasma membrane (Bowen et al, 2011; Spiliotis et al, 2008). In neurons, septins are involved in the morpho-genesis of axons and dendrites, but it is unknown if they function in polarized membrane traffic into axons and dendrites (Ageta-Ishihara et al, 2013; Boubakar et al., 2017; Hu et al, 2012; Tada et al, 2007; Xie et al, 2007). …”

Microenvironment-Driven Shift of Cohesion/Detachment Balance within Tumors Induces a Switch toward Metastasis in Neuroblastoma

“…The technique was adapted from (Boubakar et al, 2017b). 18 hours after graft, embryos were harvested in cold HBSS and extra-embryonic membranes were removed.…”

Use of zebrafish to study Shigella infection

“…Septins can recognise areas of micron-scale curvature, including the cytokinetic furrow (see Glossary, Box 1 ) and phagocytic cup (see Glossary, Box 1 ), where they act both as scaffolds for protein recruitment and as diffusion barriers for subcellular compartmentalisation ( Saarikangas and Barral, 2011 ; Mostowy and Cossart, 2012 ; Bezanilla et al, 2015 ; Cannon et al, 2017 ). Consistent with this, new work has shown that septins in neurons contribute to cell shape memory ( Boubakar et al, 2017 ) and the maturation of dendritic spines ( Yadav et al, 2017 ).

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