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Updated: Aug 16, 2026
Direct Reprogramming of Human Fibroblasts into Myoblasts to Investigate Therapies for Neuromuscular Disorders
Published on: April 3, 2021
Mutated fukutin-related protein (FKRP) localises as wild type in differentiated muscle cells
N F Dolatshad1, M Brockington, S Torelli
1Dubowitz Neuromuscular Unit, Department of Paediatrics, Hammersmith Hospital, Imperial College, Du Cane Road, London W12 ONN, UK.
Abstract:
The mechanism of disease in forms of congenital and limb girdle muscular dystrophy linked to mutations in the gene encoding for Fukutin-related protein (FKRP) has previously been associated with the mis-localisation of FKRP from the Golgi apparatus. In the present report, we have transfected V5-tagged Fukutin-related protein expression constructs into differentiated C2C12 myotubes and the tibialis anterior of normal mice. The transfection of either wild type (WT) or several mutant constructs (P448L, C318Y, L276I) into myotubes consistently showed clear co-localisation with GM130, a Golgi marker. In contrast, whilst WT and the L276I localised to the Golgi of Cos-7 cells, the P448L and C318Y was mis-localised in the majority of these undifferentiated cells. The injection of the same constructs into the tibialis anterior of mice resulted in similar localisation of both the WT and all the mutants. Immunolabelling of FKRP in the muscle of MDC1C and LGMD2I patients was found to be indistinguishable from normal controls. Overall, these data suggest that retention in the endoplasmic reticulum of FKRP is not the main mechanism of disease but that this may instead relate to a disruption of the functional activity of this putative enzyme with its substrate(s) in the Golgi.
Insights
Mutations in the Fukutin-related protein (FKRP) gene cause muscular dystrophy. This study found FKRP mislocalization is not the primary disease mechanism, suggesting Golgi dysfunction instead.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Mutations in the Fukutin-related protein (FKRP) gene are linked to congenital and limb girdle muscular dystrophies.
- Previous hypotheses suggested FKRP mislocalization from the Golgi apparatus as the primary disease mechanism.
Purpose of the Study:
- To investigate the cellular localization of wild-type (WT) and mutant FKRP constructs.
- To determine if FKRP mislocalization from the Golgi is the main mechanism driving FKRP-associated muscular dystrophies.
Main Methods:
- Transfection of V5-tagged FKRP expression constructs (WT, P448L, C318Y, L276I) into differentiated C2C12 myotubes and mouse tibialis anterior muscle.
- Localization studies using GM130 as a Golgi marker in transfected myotubes and Cos-7 cells.
- Immunolabeling of FKRP in muscle biopsies from MDC1C and LGMD2I patients.
Main Results:
- WT and L276I FKRP localized to the Golgi in Cos-7 cells, while P448L and C318Y mutants were mislocalized in undifferentiated cells.
- In differentiated C2C12 myotubes and mouse muscle, all FKRP constructs (WT and mutants) showed clear co-localization with the Golgi marker.
- FKRP immunolabeling in MDC1C and LGMD2I patient muscle was similar to normal controls.
Conclusions:
- FKRP retention in the endoplasmic reticulum is unlikely to be the primary disease mechanism in FKRP-associated muscular dystrophies.
- Disease pathogenesis may involve disruption of FKRP's functional activity or substrate interactions within the Golgi apparatus.
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