Subcellular receptor redistribution and enhanced microspike formation by a Ret receptor preferentially recruiting Dok

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Ret is a receptor tyrosine kinase essential for nervous system development.
• Ret signaling relies on intracellular tyrosine 1062 recruitment of phosphotyrosine binding (PTB) proteins like Shc, Frs2, and Dok.
• These adaptor proteins mediate critical biological effects including cell proliferation, migration, and neurite growth.

Purpose of the Study:

• To investigate how specific Ret adaptor protein engagement influences downstream signaling and neuronal function.
• To explore the consequences of rewiring Ret to preferentially recruit Dok over Shc and Frs2.

Main Methods:

• A single amino acid substitution was introduced in the PTB domain binding sequence of Ret to create a Dok-preferring receptor (Ret(Dok+)).
• Comparative analysis of Ret(Dok+) and wild-type Ret (Ret(WT)) signaling pathways, including MAP kinase and Akt activation.
• Microscopic observation of cellular responses, such as microspike formation and receptor localization, following ligand stimulation.

Main Results:

• Ret(Dok+) exhibited sustained MAP kinase activation and diminished Akt signaling compared to Ret(WT).
• Ligand stimulation of Ret(Dok+) induced rapid and massive formation of microspikes, structures involved in neurite growth.
• Ret(Dok+) receptors clustered at the tips of these microspikes, correlating with Cdc42 activation.

Conclusions:

• The engagement of different adaptor proteins by Ret leads to distinct downstream signaling cascades and cellular functions in neurons.
• Preferential recruitment of Dok by Ret triggers rapid receptor relocation and promotes microspike formation, suggesting a key role in initiating neurite outgrowth.