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Updated: Dec 26, 2025
A Phenotyping Regimen for Genetically Modified Mice Used to Study Genes Implicated in Human Diseases of Aging
Published on: July 14, 2016
Knockin mouse model of the human CFL2 p.A35T mutation results in a unique splicing defect and severe myopathy
Samantha M Rosen1,2,3, Mugdha Joshi1, Talia Hitt1
1Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Abstract:
Cofilin-2 is an actin-binding protein that is predominantly expressed in skeletal and cardiac muscles and belongs to the AC group of proteins, which includes cofilin-1 and destrin. In humans, cofilin-2 (CFL2) mutations have been associated with congenital myopathies that include nemaline and myofibrillar myopathy. To understand the pathogenicity of the human CFL2 mutation, p.A35T, that first linked cofilin-2 with the human disease, we created a knock-in mouse model. The Cfl2A35T/A35T (KI) mice were indistinguishable from their wild-type littermates at birth, but they rapidly worsened and died by postnatal day 9. The phenotypic, histopathologic and molecular findings mimicked the constitutive Cfl2-knockout (KO) mice described previously, including sarcomeric disruption and actin accumulations in skeletal muscles and negligible amounts of cofilin-2 protein. In addition, KI mice demonstrated a marked reduction in Cfl2 mRNA levels in various tissues including skeletal muscles. Further investigation revealed evidence of alternative splicing with the presence of two alternate transcripts of smaller size. These alternate transcripts were expressed at very low levels in the wild-type mice and were significantly upregulated in the mutant mice, indicating that pre-translational splicing defects may be a critical component of the disease mechanism associated with the mutation. Evidence of reduced expression of the full-length CFL2 transcript was also observed in the muscle biopsy sample of the patient with p.A35T mutation.
Insights
Mutations in cofilin-2 (CFL2) cause congenital myopathies. A knock-in mouse model for the p.A35T CFL2 mutation revealed severe muscle defects and premature death, linked to splicing abnormalities.
Area of Science:
- Muscle biology
- Molecular genetics
- Disease mechanisms
Background:
- Cofilin-2 (CFL2) is a crucial actin-binding protein in muscle.
- Mutations in CFL2 are linked to human congenital myopathies like nemaline and myofibrillar myopathy.
Purpose of the Study:
- To investigate the pathogenicity of the human CFL2 p.A35T mutation.
- To understand the molecular mechanisms underlying CFL2-associated myopathies using a mouse model.
Main Methods:
- Generated a knock-in mouse model (Cfl2A35T/A35T) expressing the human p.A35T CFL2 mutation.
- Performed phenotypic, histopathologic, and molecular analyses of mutant mice.
- Analyzed Cfl2 mRNA levels and alternative splicing in tissues and patient samples.
Main Results:
- Cfl2A35T/A35T mice exhibited severe muscle pathology and died by postnatal day 9.
- Phenotypes mimicked constitutive Cfl2-knockout mice, showing sarcomeric disruption and actin accumulation.
- Mutant mice displayed reduced full-length Cfl2 mRNA and upregulation of smaller, alternatively spliced transcripts.
Conclusions:
- The p.A35T CFL2 mutation leads to severe congenital myopathy in mice.
- Pre-translational splicing defects and reduced full-length CFL2 expression are critical in the disease mechanism.
- Findings provide insights into CFL2-related myopathies and validate the mouse model for further study.
