Abstract
SH2B1 is an adaptor protein known to enhance neurite outgrowth. In this study, we provide evidence suggesting that the SH2B1 level is increased during in vitro culture of hippocampal neurons, and the β isoform (SH2B1β) is the predominant isoform. The fact that formation of filopodia is prerequisite for neurite initiation suggests that SH2B1 may regulate filopodium formation and thus neurite initiation. To investigate whether SH2B1 may regulate filopodium formation, the effect of SH2B1 and a membrane and actin regulator, IRSp53 (insulin receptor tyrosine kinase substrate p53), is investigated. Overexpressing both SH2B1β and IRSp53 significantly enhances filopodium formation, neurite outgrowth, and branching. Both in vivo and in vitro data show that SH2B1 interacts with IRSp53 in hippocampal neurons. This interaction depends on the N-terminal proline-rich domains of SH2B1. In addition, SH2B1 and IRSp53 co-localize at the plasma membrane, and their levels increase in the Triton X-100-insoluble fraction of developing neurons. These findings suggest that SH2B1-IRSp53 complexes promote the formation of filopodia, neurite initiation, and neuronal branching.
Highlights
Filopodium formation is a prerequisite for neurite initiation
These findings suggest that SH2B1-IRSp53 complexes promote the formation of filopodia, neurite initiation, and neuronal branching
On day in vitro (DIV) 0, primary neurons were cultured in minimum essential media/high glucose medium supplemented with 5% fetal bovine serum (FBS) and 5% horse serum under 5% CO2 conditions
Summary
Filopodium formation is a prerequisite for neurite initiation. Results: SH2B1 interacts with IRSp53 and promotes neurite outgrowth of hippocampal neurons. To investigate whether SH2B1 may regulate filopodium formation, the effect of SH2B1 and a membrane and actin regulator, IRSp53 (insulin receptor tyrosine kinase substrate p53), is investigated Overexpressing both SH2B1 and IRSp53 significantly enhances filopodium formation, neurite outgrowth, and branching. Both in vivo and in vitro data show that SH2B1 interacts with IRSp53 in hippocampal neurons. SH2B1 and IRSp53 co-localize at the plasma membrane, and their levels increase in the Triton X-100-insoluble fraction of developing neurons These findings suggest that SH2B1-IRSp53 complexes promote the formation of filopodia, neurite initiation, and neuronal branching. Using the hippocampal and cortical neuron culture, we tested the hypothesis that SH2B1 promotes filopodium formation and neurite initiation by interacting with IRSp53
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