SH2B1β (SH2-Bβ) Enhances Expression of a Subset of Nerve Growth Factor-Regulated Genes Important for Neuronal Differentiation Including Genes Encoding Urokinase Plasminogen Activator Receptor and Matrix Metalloproteinase 3/10

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Abstract
Previous work showed that the adapter protein SH2B adapter protein 1β (SH2B1) (SH2-B) binds to the activated form of the nerve growth factor (NGF) receptor TrkA and is critical for both NGF-dependent neurite outgrowth and maintenance. To identify SH2B1β-regulated genes critical for neurite outgrowth, we performed microarray analysis of control PC12 cells and PC12 cells stably overexpressing SH2B1β (PC12-SH2B1β) or the dominant-negative SH2B1β(R555E) [PC12-SH2B1β(R555E)]. NGF-induced microarray expression of Plaur and Mmp10 genes was greatly enhanced in PC12-SH2B1β cells, whereas NGF-induced Plaur and Mmp3 expression was substantially depressed in PC12-SH2B1β(R555E) cells. Plaur, Mmp3, and Mmp10 are among the 12 genes most highly up-regulated after 6 h of NGF. Their protein products [urokinase plasminogen activator receptor (uPAR), matrix metalloproteinase 3 (MMP3), and MMP10] lie in the same pathway of extracellular matrix degradation; uPAR has been shown previously to be critical for NGF-induced neurite outgrowth. Quantitative real-time PCR analysis revealed SH2B1β enhancement of NGF induction of all three genes and the suppression of NGF induction of all three when endogenous SH2B1 was reduced using short hairpin RNA against SH2B1 and in PC12-SH2B1β(R555E) cells. NGF-induced levels of uPAR and MMP3/10 and neurite outgrowth through Matrigel (MMP3-dependent) were also increased in PC12-SH2B1β cells. These results suggest that SH2B1β stimulates NGF-induced neuronal differentiation at least in part by enhancing expression of a specific subset of NGF-sensitive genes, including Plaur, Mmp3, and/or Mmp10, required for neurite outgrowth.