FKRP-dependent glycosylation of fibronectin regulates muscle pathology in muscular dystrophy
Alasdair J. Wood, Chi‐Hung Lin, M. Li, Krishnatej Nishtala, Sara Alaei, Fernando J. Rossello, C. Sonntag, Lucy Hersey, Lee B. Miles, Christoph Krisp, Stefanie Dudczig, Alex J. Fulcher, Sara Gibertini, Paul J. Conroy, Ashley Siegel, Marina Mora, Patricia R. Jusuf, Nicolle H. Packer, Peter D. Currie
Abstract
The muscular dystrophies encompass a broad range of pathologies with varied clinical outcomes. In the case of patients carrying defects in fukutin-related protein (FKRP), these diverse pathologies arise from mutations within the same gene. This is surprising as FKRP is a glycosyltransferase, whose only identified function is to transfer ribitol-5-phosphate to α-dystroglycan (α-DG). Although this modification is critical for extracellular matrix attachment, α-DG's glycosylation status relates poorly to disease severity, suggesting the existence of unidentified FKRP targets. Here we reveal that FKRP directs sialylation of fibronectin, a process essential for collagen recruitment to the muscle basement membrane. Thus, our results reveal that FKRP simultaneously regulates the two major muscle-ECM linkages essential for fibre survival, and establishes a new disease axis for the muscular dystrophies.