A Phosphatidylinositol Lipids System, Lamellipodin, and Ena/VASP Regulate Dynamic Morphology of Multipolar Migrating Cells in the Developing Cerebral Cortex

Abstract

In the developing mammalian cerebral cortex, excitatory neurons are generated in the ventricular zone (VZ) and subventricular zone; these neurons migrate toward the pial surface. The neurons generated in the VZ assume a multipolar morphology and remain in a narrow region called the multipolar cell accumulation zone (MAZ) for ϳ24 h, in which they extend and retract multiple processes dynamically. They eventually extend an axon tangentially and begin radial migration using a migratory mode called locomotion. Despite the potential biological importance of the process movement of multipolar cells, the molecular mechanisms remain to be elucidated. Here, we observed that the processes of mouse multipolar cells were actin rich and morphologically resembled the filopodia and lamellipodia in growth cones; thus, we focused on the actin-remodeling proteins Lamellipodin (Lpd) and Ena/vasodilator-stimulated phosphoprotein (VASP). Lpd binds to phosphatidylinositol (3,4)-bisphosphate [PI(3,4)P 2 ] and recruits Ena/VASP, which promotes the assembly of actin filaments, to the plasma membranes. In situ hybridization and immunohistochemistry revealed that Lpd is expressed in multipolar cells in the MAZ. The functional silencing of either Lpd or Ena/VASP decreased the number of primary processes. Immunostaining and a Förster resonance energy transfer analysis revealed the subcellular localization of PI(3,4)P 2 at the tips of the processes. A knockdown experiment and treatment with an inhibitor for Src homology 2-containing inositol phosphatase-2, a 5-phosphatase that produces PI(3,4)P 2 from phosphatidylinositol (3,4,5)-triphosphate, decreased the number of primary processes. Our observations suggest that PI(3,4)P 2 , Lpd, and Ena/VASP are involved in the process movement of multipolar migrating cells.

Transcriptome Analysis of Newt Lens Regeneration Reveals Distinct Gradients in Gene Expression Patterns

“…KLHL3 and MYO5A are playing roles in molecular transport [127], [128]. PLEK2 and VASP are related to cell movement [129], [130] and SYNE1 and WDR1 are linking cytoskeleton with other proteins [131], [132].…”

How does SHIP1/2 balance PtdIns(3,4)P2 and does it signal independently of its phosphatase activity?

“…Lamellipodin binding to PtdIns(3,4)P 2 helps to recruit Ena/VASP, which promotes the assembly of actin filaments, to the plasma membranes of multipolar neurons. Deletion of one of those two proteins was shown to inhibit the migration process .…”

Phosphatidylinositol-3,4-Bisphosphate and Its Binding Protein Lamellipodin Regulate Chemotaxis of Malignant B Lymphocytes

“…mCherry-tagged membrane-targeted INPP4B wild-type (WT) or catalytically inactive mutant constructs were provided by V. Haucke (26). EGFP-tagged WT or PH domain-deleted human Lpd (Lpd WT-GFP or Lpd DPH-GFP), cloned in the expression vector pCAGGS (36), was a gift from K. Nakajima (35). For Lpd KD, a TRC lentiviral (pLKO.1-puro) short hairpin RNA (shRNA) clone targeting Lpd coding sequence (59-GCCAGGACTATCGGAACA-AAT-39) (Thermo Scientific) was used, along with a pLKO.1-puro nonmammalian shRNA control vector (Sigma-Aldrich, SHC002).…”

“…Lpd was shown to mediate random motility in breast cancer cells (29,34) as well as extension of neuronal processes (35). It remains unknown whether Lpd is involved in directional migration in response to specific chemotactic stimuli, and whether the function of Lpd in promoting cell migration depends on its PI(3,4)P2-binding PH domain.…”