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An Efficient Protocol to Assess ERK Activity Modulation in Early Zebrafish Noonan Syndrome Models via Live FRET Microscopy and Immunofluorescence
Published on: May 2, 2025
MEK-ERK pathway modulation ameliorates disease phenotypes in a mouse model of Noonan syndrome associated with the
Xue Wu1, Jeremy Simpson, Jenny H Hong
1Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
The Journal of Clinical Investigation
|February 23, 2011
Summary
Mutations in RAF1 cause Noonan syndrome (NS) and hypertrophic cardiomyopathy (HCM). MEK-ERK pathway activation is key, and inhibiting MEK in mice corrected NS and HCM-like features.
Area of Science:
- Cardiovascular Biology
- Genetics
- Developmental Biology
Background:
- Hypertrophic cardiomyopathy (HCM) is a primary cause of sudden cardiac death in pediatric and young adult populations.
- The RAS-RAF-MEK-ERK MAPK pathway's role in HCM pathogenesis is debated, though mutations in this pathway cause RASopathies like Noonan syndrome (NS).
- Germline mutations in RAF1, a component of this pathway, are found in 3-5% of NS cases, with specific mutations strongly linked to HCM.
Purpose of the Study:
- To investigate the pathogenesis of HCM associated with RAF1 mutations in Noonan syndrome.
- To determine if enhanced MEK-ERK pathway activity is critical for RAF1-mutant NS phenotypes, including HCM.
- To explore potential therapeutic strategies targeting the MEK-ERK pathway for RASopathies.
Main Methods:
- Generation of knockin mice expressing the Noonan syndrome-associated Raf1(L613V) mutation.
- Phenotypic characterization of L613V/+ mice, including growth, craniofacial features, hematology, cardiac function, and gene expression.
- Assessment of MEK-ERK pathway activation in response to agonists and the effects of postnatal MEK inhibition.
Main Results:
- L613V/+ mice recapitulated key features of NS, including short stature, craniofacial dysmorphia, and hematologic abnormalities.
- Cardiac analysis revealed eccentric hypertrophy, aberrant fetal gene expression, and decompensation under pressure overload in L613V/+ mice.
- Enhanced MEK-ERK activation was observed, and postnatal MEK inhibition successfully normalized growth, facial, and cardiac defects.
Conclusions:
- RAF1 mutations in NS lead to distinct pathological effects compared to other RASopathy genes.
- Enhanced MEK-ERK pathway activity is essential for the development of HCM and other phenotypes associated with RAF1-mutant NS.
- Targeting the MEK-ERK pathway offers a potential mutation-specific therapeutic approach for RASopathies.
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