The tyrosine kinase receptor ErbB4 is involved in a number of cellular responses, such as proliferation, survival, differentiation and chemotaxis. Literature data obtained by ErbB4 knock out mice and by ErbB4 dominant negative suggest that this receptor is implicated in neuron migration. Two pairs of naturally occurring ErbB4 isoforms, differing in their juxtamembrane (JM) or carboxyl termini (cyt), have been described: one isoforms pair is characterized by alternative splicing of exons conferring (JMa) or not (JMb) susceptibility to a proteolytic cleavage operated by a metalloprotease. The other isoforms pair is characterized by the presence (cyt1) or absence (cyt2) of a cytoplasmic exon containing a docking site for phosphatidylinositol-3-kinase (PI-3 Kinase). To examine the role of ErbB4 in neuron migration, the four ErbB4 full length cDNA isoforms were cloned and stably transfected in ST14A cells, a neural progenitor cell line endogenously expressing ErbB1, ErbB2 and ErbB3. The ability of the four ErbB4 isoforms to induce chemotaxis in response to neuregulin1β1 (NRG1β1) stimulation was tested. Only ErbB4 expressing cells, stimulated with NRG1β1, show a significant increased migration. By immunoprecipitation assays, we showed that the NRG1β1 stimulus induces ErbB4 tyrosine phosphorylation and phosphatidylinositol-3-kinase (PI3-kinase) recruitment. Moreover, further assays showed that PI3-kinase inhibition dramatically reduce migratory activity. However, accordingly to literature data, only the ErbB4 isoform cyt1 should interact with the PI3-kinase. Nevertheless, ErbB4 can heterodimerize with ErbB3, which harbours several PI3-kinase binding motifs in its carboxyl terminal domain. Actually, by transient transfection assays, we showed that ErbB4 isoform cyt2 can recruit PI3-kinase through ErbB3 receptor. Our data show that ErbB4 signalling, via PI3-kinase activation, plays a fundamental role in controlling NRG1β1 induced migration. This work was supported by a grant from Compagnia di S. Paolo, MIUR-PRIN 2001 and PRONEURO (FIRB RBNE01WY7P).
ErbB4 expression in neural progenitor cells is necessary to mediate neuregulin1β1 induced migration
GAMBAROTTA, Giovanna;FASOLO, Aldo;PERROTEAU, Isabelle
2004-01-01
Abstract
The tyrosine kinase receptor ErbB4 is involved in a number of cellular responses, such as proliferation, survival, differentiation and chemotaxis. Literature data obtained by ErbB4 knock out mice and by ErbB4 dominant negative suggest that this receptor is implicated in neuron migration. Two pairs of naturally occurring ErbB4 isoforms, differing in their juxtamembrane (JM) or carboxyl termini (cyt), have been described: one isoforms pair is characterized by alternative splicing of exons conferring (JMa) or not (JMb) susceptibility to a proteolytic cleavage operated by a metalloprotease. The other isoforms pair is characterized by the presence (cyt1) or absence (cyt2) of a cytoplasmic exon containing a docking site for phosphatidylinositol-3-kinase (PI-3 Kinase). To examine the role of ErbB4 in neuron migration, the four ErbB4 full length cDNA isoforms were cloned and stably transfected in ST14A cells, a neural progenitor cell line endogenously expressing ErbB1, ErbB2 and ErbB3. The ability of the four ErbB4 isoforms to induce chemotaxis in response to neuregulin1β1 (NRG1β1) stimulation was tested. Only ErbB4 expressing cells, stimulated with NRG1β1, show a significant increased migration. By immunoprecipitation assays, we showed that the NRG1β1 stimulus induces ErbB4 tyrosine phosphorylation and phosphatidylinositol-3-kinase (PI3-kinase) recruitment. Moreover, further assays showed that PI3-kinase inhibition dramatically reduce migratory activity. However, accordingly to literature data, only the ErbB4 isoform cyt1 should interact with the PI3-kinase. Nevertheless, ErbB4 can heterodimerize with ErbB3, which harbours several PI3-kinase binding motifs in its carboxyl terminal domain. Actually, by transient transfection assays, we showed that ErbB4 isoform cyt2 can recruit PI3-kinase through ErbB3 receptor. Our data show that ErbB4 signalling, via PI3-kinase activation, plays a fundamental role in controlling NRG1β1 induced migration. This work was supported by a grant from Compagnia di S. Paolo, MIUR-PRIN 2001 and PRONEURO (FIRB RBNE01WY7P).
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