Knockin mouse model of the human CFL2 p.A35T mutation results in a unique splicing defect and severe myopathy phenotype

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.

Recent advances in nemaline myopathy

“…A novel KI-mouse model harbouring the first human missense mutation linking the gene to NM mimicked the phenotype of the KO mice. The KI model was normal at birth, but rapidly deteriorated and died by postnatal day nine [83] .…”

Comparative Analysis of Skeletal Muscle DNA Methylation and Transcriptome of the Chicken Embryo at Different Developmental Stages

“…We chose to study the function of the CFL2 gene in embryonic skeletal muscle development further. The role of CFL2 has been studied in cardiac muscle (Vafiadaki et al, 2020) and many types of congenital myopathies (Rosen et al, 2020), but not in chicken skeletal muscle development. Qian et al (2017) found significant differences in the CFL2 gene in chicken leg muscle transcriptomes of different ages.…”

New Insight into Muscle-Type Cofilin (CFL2) as an Essential Mediator in Promoting Myogenic Differentiation in Cattle

“…The HEK293, 293A and C2C12 cell lines were the preservative cell lines from American ATCC in our laboratory. Primary bovine myoblasts (PBMs) were harvested from fetal bovine longissimus dorsi muscle and cultured by collagenase-I digestion as previously described [ 13 ]. Cell lines and PBMs were cultured following our previously established protocols [ 6 ].…”

“…Considering CFL2 a candidate gene for nemaline myopathy, some studies have shown that the mutation from G to A in the coding region position 103 of the CFL2 gene can induce the occurrence of human nemaline myopathy, and the CFL2 gene can regulate the expression of key factors CAM and MEF2C in myofibroblast signal pathway, resulting in a change in muscle properties [ 12 ]. A CFL2 A35T/A35T knock-in mouse model indicated that the expression levels of CFL2 mRNA and full-length transcript decreased significantly in skeletal muscles and muscle biopsy samples of a p.A35T mutation patient, respectively [ 13 ]. Sun examined the association of the CFL2 gene polymorphisms with performance traits in Qinchuan (QC) cattle.…”