AI Article Synopsis

  • The Shoc2 scaffold protein is essential for transmitting signals in the EGFR-mediated ERK1/2 pathway, but how it regulates this process is not fully understood.
  • Mutations in Shoc2 are linked to Noonan Syndrome with Loose anagen Hair, complicating the study of its function since Shoc2 lacks known enzymatic activity.
  • This research found that while Shoc2 variants cannot fully activate ERK1/2 phosphorylation as effectively as wild-type Shoc2, they can enhance ERK1/2 phosphorylation when both AKT and ERK1/2 pathways are activated, indicating a complex regulatory role for Shoc2 in signaling.

Article Abstract

The Shoc2 scaffold protein is crucial in transmitting signals within the Epidermal Growth Factor Receptor (EGFR)-mediated Extracellular signal-regulated Kinase (ERK1/2) pathway. While the significance of Shoc2 in this pathway is well-established, the precise mechanisms through which Shoc2 governs signal transmission remain to be fully elucidated. Hereditary mutations in Shoc2 are responsible for Noonan Syndrome with Loose anagen Hair (NSLH). However, due to the absence of known enzymatic activity in Shoc2, directly assessing how these mutations affect its function is challenging. ERK1/2 phosphorylation is used as a primary parameter of Shoc2 function, but the impact of Shoc2 mutants on the pathway activation is unclear. This study investigates how the NSLH-associated Shoc2 variants influence EGFR signals in the context of the ERK1/2 and AKT downstream signaling pathways. We show that when the ERK1/2 pathway is a primary signaling pathway activated downstream of EGFR, Shoc2 variants cannot upregulate ERK1/2 phosphorylation to the level of the WT Shoc2. Yet, when the AKT and ERK1/2 pathways were activated, in cells expressing Shoc2 variants, ERK1/2 phosphorylation was higher than in cells expressing WT Shoc2. We found that, in cells expressing the Shoc2 NSLH mutants, the AKT signaling pathway triggers the PAK activation, followed by phosphorylation and Raf-1/MEK1/2 /ERK1/2 signaling axis activation. Hence, our studies reveal a previously unrecognized feedback regulation downstream of the EGFR and provide evidence for the Shoc2 role as a "gatekeeper" in controlling the selection of downstream effectors within the EGFR signaling network.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10769455PMC
http://dx.doi.org/10.1101/2023.12.23.573219DOI Listing

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