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Mouse semaphorin H induces PC12 cell neurite outgrowth activating Ras-mitogen-activated protein kinase signaling
1Group of Neurobiology, School of Allied Health Sciences, Osaka University Faculty of Medicine, Yamadaoka 1-7, Suita-shi, Osaka, 565-0871, Japan.
Abstract:
We recently showed that mouse semaphorin H (MSH), a secreted semaphorin molecule, acts as a chemorepulsive factor on sensory neurites. In this study, we found for the first time that MSH induces neurite outgrowth in PC12 cells in a dose-dependent manner. Comparison of Ras-mitogen-activated protein kinase (MAPK) signaling pathways between MSH and nerve growth factor (NGF) revealed that these pathways are crucial for MSH action as well as NGF. K-252a, an inhibitor of tyrosine autophosphorylation of tyrosine kinase receptors (Trks), did not inhibit the action of MSH, suggesting that MSH action occurs via a different receptor than NGF. L- and N-types of voltage-dependent Ca(2+) channel blockers, diltiazem and omega-conotoxin, inhibited MSH-induced neurite outgrowth and MAPK phosphorylation in a Ca(2+)-dependent manner. A transient elevation in intracellular Ca(2+) level was observed upon MSH stimulation. These findings suggest that extracellular Ca(2+) influx, followed by activation of the Ras-MAPK signaling pathway, is required for MSH induced PC12 cell neurite outgrowth.
Insights
Mouse semaphorin H (MSH) promotes neurite outgrowth in PC12 cells. This process involves calcium influx and the Ras-MAPK pathway, distinct from nerve growth factor (NGF) signaling.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Mouse semaphorin H (MSH) is a secreted molecule previously identified as a chemorepulsive factor for sensory neurites.
- Understanding the molecular mechanisms regulating neurite outgrowth is crucial for neural development and regeneration.
Purpose of the Study:
- To investigate the role of mouse semaphorin H (MSH) in inducing neurite outgrowth in PC12 cells.
- To elucidate the signaling pathways involved in MSH-mediated neurite outgrowth and compare them with nerve growth factor (NGF) signaling.
Main Methods:
- PC12 cells were treated with varying concentrations of MSH to assess neurite outgrowth.
- Ras-mitogen-activated protein kinase (MAPK) signaling pathways were analyzed.
- The effects of tyrosine kinase receptor (Trk) inhibitors (K-252a) and voltage-dependent calcium channel blockers (diltiazem, omega-conotoxin) were evaluated.
- Intracellular calcium levels were measured upon MSH stimulation.
Main Results:
- MSH induced dose-dependent neurite outgrowth in PC12 cells.
- The Ras-MAPK pathway was essential for MSH-induced neurite outgrowth, similar to NGF.
- MSH action did not involve tyrosine kinase receptors (Trks), indicating a different receptor mechanism than NGF.
- Calcium channel blockers inhibited MSH-induced neurite outgrowth and MAPK phosphorylation, demonstrating a Ca(2+)-dependent mechanism.
- MSH stimulation led to a transient increase in intracellular Ca(2+) levels.
Conclusions:
- MSH promotes neurite outgrowth in PC12 cells through a mechanism distinct from NGF.
- Extracellular calcium influx is a critical step, activating the Ras-MAPK signaling pathway for MSH-induced neurite outgrowth.