The small-GTPase Rac1 is a key molecular regulator linking extracellular signals to actin cytoskeleton dynamics. Loss-of-function mutations in RAC1 and other genes of the Rac signaling pathway have been implicated in the pathogenesis of Intellectual Disability (ID). The Rac1 activity is negatively controlled by GAP proteins, however the effect of Rac1 hyperactivity on neuronal networking in vivo has been poorly studied. ArhGAP15 is a Rac-specific negative regulator, expressed in the main subtypes of pyramidal cortical neurons. In the absence of ArhGAP15, cortical pyramidal neurons show defective neuritogenesis, delayed axonal elongation, reduced dendritic branching, both in vitro and in vivo. These phenotypes are associated with altered actin dynamics at the growth cone due to increased activity of the PAK-LIMK pathway and hyperphosphorylation of ADF/cofilin. These results can be explained by shootin1 hypo-phosphorylation and uncoupling with the adhesion system. Functionally, ArhGAP15-/- mice exhibit decreased synaptic density, altered electroencephalographic rhythms and cognitive deficits. These data suggest that both hypo- and hyperactivation of the Rac pathway due to mutations in Rac1 regulators can result in conditions of ID, and that a tight regulation of Rac1 activity is required to attain the full complexity of the cortical networks.

Hyperactivity of Rac1-GTPase pathway impairs neuritogenesis of cortical neurons by altering actin dynamics

Zamboni, Valentina;Armentano, Maria;Berto, Gaia;Ciraolo, Elisa;Ghigo, Alessandra;Garzotto, Donatella;Dicunto, Ferdinando;Parmigiani, Elena;Boido, Marina;Vercelli, Alessandro;Mauro, Alessandro;Priano, Lorenzo;Hirsch, Emilio
Co-last
;
Merlo, Giorgio R.
Co-last
2018-01-01

Abstract

The small-GTPase Rac1 is a key molecular regulator linking extracellular signals to actin cytoskeleton dynamics. Loss-of-function mutations in RAC1 and other genes of the Rac signaling pathway have been implicated in the pathogenesis of Intellectual Disability (ID). The Rac1 activity is negatively controlled by GAP proteins, however the effect of Rac1 hyperactivity on neuronal networking in vivo has been poorly studied. ArhGAP15 is a Rac-specific negative regulator, expressed in the main subtypes of pyramidal cortical neurons. In the absence of ArhGAP15, cortical pyramidal neurons show defective neuritogenesis, delayed axonal elongation, reduced dendritic branching, both in vitro and in vivo. These phenotypes are associated with altered actin dynamics at the growth cone due to increased activity of the PAK-LIMK pathway and hyperphosphorylation of ADF/cofilin. These results can be explained by shootin1 hypo-phosphorylation and uncoupling with the adhesion system. Functionally, ArhGAP15-/- mice exhibit decreased synaptic density, altered electroencephalographic rhythms and cognitive deficits. These data suggest that both hypo- and hyperactivation of the Rac pathway due to mutations in Rac1 regulators can result in conditions of ID, and that a tight regulation of Rac1 activity is required to attain the full complexity of the cortical networks.
2018
8
1
7254
7269
www.nature.com/srep/index.html
Multidisciplinary
Zamboni, Valentina; Armentano, Maria; Berto, Gaia; Ciraolo, Elisa; Ghigo, Alessandra; Garzotto, Donatella; Umbach, Alessandro; Dicunto, Ferdinando; Pa...espandi
File in questo prodotto:
File Dimensione Formato  
41598_2018_Article_25354.pdf

Accesso aperto

Tipo di file: PDF EDITORIALE
Dimensione 4.44 MB
Formato Adobe PDF
4.44 MB Adobe PDF Visualizza/Apri
Zamboni et al 2018 Sci Rep.pdf

Accesso riservato

Tipo di file: PDF EDITORIALE
Dimensione 4.44 MB
Formato Adobe PDF
4.44 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1668952
Citazioni
  • ???jsp.display-item.citation.pmc??? 22
  • Scopus 26
  • ???jsp.display-item.citation.isi??? 27
social impact