A new mouse model of Ehlers-Danlos syndrome generated using CRISPR/Cas9-mediated genomic editing

Abstract

Musculocontractural Ehlers-Danlos syndrome (mcEDS) is caused by generalized depletion of dermatan sulfate (DS) due to biallelic pathogenic variants in CHST14 encoding dermatan 4-O-sulfotransferase 1 (D4ST1) (mcEDS-CHST14). Here, we generated mouse models for mcEDS-CHST14 carrying homozygous mutations (1 bp deletion or 6 bp insertion/10 bp deletion) in Chst14 through CRISPR/Cas9-genome engineering to overcome perinatal lethality in conventional Chst14-deleted knockout mice. DS depletion was detected in the skeletal muscle of these genome-edited mutant mice, consistent with loss of D4ST1 activity. The mutant mice showed common pathophysiological features, regardless of the variant, including growth impairment and skin fragility. Notably, we identified myopathy-related phenotypes. Muscle histopathology showed variation in fiber size and spread of the muscle interstitium. Decorin localized diffusely in the spread endomysium and perimysium of skeletal muscle, unlike in wild-type mice. The mutant mice showed lower grip strength and decreased exercise capacity compared to wild-type, and morphometric evaluation demonstrated thoracic kyphosis in mutant mice. The established CRISPR/Cas9-engineered Chst14 mutant mice would be a useful model to further our understanding of the mcEDS pathophysiology and in the development of novel treatment strategies.

Alterations in glycosaminoglycan biosynthesis associated with the Ehlers-Danlos syndromes

“…Mice deficient for Chst14 showed growth impairment with smaller body mass, reduced fertility, kinked tail, and increased skin fragility. (131,132) Moreover, the skin of Chst14 -/mice showed decreased amounts of DS and elevated CS levels. Similar to the findings in mcEDS-CHST14 patients, rod-shaped linear GAG chains that protruded outside of the collagen fibrils were found in Chst14 -/mice, in contrast to those being round and wrapping around the collagen fibrils in wild-type mice.…”

“…Similar to the findings in mcEDS-CHST14 patients, rod-shaped linear GAG chains that protruded outside of the collagen fibrils were found in Chst14 -/mice, in contrast to those being round and wrapping around the collagen fibrils in wild-type mice. (132,133) Furthermore, Chst14 -/mice showed thoracic kyphosis, and myopathy-related phenotypes such as lower grip strength and decreased exercise capacity, with decreased DS in muscle and variation in fiber size and spread of the muscle interstitium. (132,134) Additionally, Chst14 -/mice provided evidence for an overall negative impact of DS on peripheral nerve regeneration (131) but beneficial activity in central nervous system regeneration, which could result from differences in DS proteoglycans levels and their interaction partners between the peripheral and central nervous systems.…”

“…(132,133) Furthermore, Chst14 -/mice showed thoracic kyphosis, and myopathy-related phenotypes such as lower grip strength and decreased exercise capacity, with decreased DS in muscle and variation in fiber size and spread of the muscle interstitium. (132,134) Additionally, Chst14 -/mice provided evidence for an overall negative impact of DS on peripheral nerve regeneration (131) but beneficial activity in central nervous system regeneration, which could result from differences in DS proteoglycans levels and their interaction partners between the peripheral and central nervous systems. ( 135) Chst14 -/mice also showed impaired spatial learning and memory and demonstrated that DS is indispensable for synaptic plasticity in the hippocampus, which might be attributed to impaired Akt/mTOR-signalling.…”

The predictive value of models of neuromuscular disorders to potentiate clinical translation

“…More recently, however, gene editing has facilitated and accelerated the development of models carrying specific mutations, thereby greatly expanding the availability of clinically relevant models. CRISPR/Cas9-mediated gene editing, which enables precise introduction of mutations, has further advanced the generation of animal models, allowing for faster and cheaper production ( Hinman et al, 2021 ; Nitahara-Kasahara et al, 2021 ). Also, the use of humanized mouse models, carrying the human gene with specific patient-derived causative mutations, has benefited from these developments.…”

Pathophysiological Investigation of Skeletal Deformities of Musculocontractural Ehlers–Danlos Syndrome Using Induced Pluripotent Stem Cells

“…Therefore, we speculated that bone lesions in mcEDS- CHST14 patients may be associated with impaired bone mineralization caused by the abnormal organization of collagen networks mediated by decorin and its GAG chains. However, difficulty obtaining tissue samples from patients and limited skeletal phenotypes in mouse models [ 13 , 14 ] hampered our ability to dissect the pathogenesis of skeletal deformities in mcEDS- CHST14 .…”