Skeletal dysplasia-causing mutations in TRPV4 alter the chondrocyte transcriptomic response to mechanical loading

Area of Science:

• Biochemistry
• Genetics
• Developmental Biology

Background:

• Transient receptor potential vanilloid 4 (TRPV4) is crucial for chondrocyte function and cartilage homeostasis.
• Gain-of-function TRPV4 mutations (V620I, T89I) cause skeletal dysplasias by suppressing hypertrophic differentiation.
• The precise impact of these mutations on chondrocyte mechanotransduction is not fully understood.

Purpose of the Study:

• To investigate how V620I and T89I TRPV4 mutations affect chondrocyte mechanotransduction.
• To elucidate the molecular mechanisms underlying TRPV4-associated skeletal disorders.

Main Methods:

• Generated CRISPR-edited human-induced pluripotent stem cells (hiPSCs) with V620I or T89I TRPV4 mutations.
• Created tissue-engineered cartilage constructs from these hiPSCs.
• Applied physiological compressive mechanical loading to wild-type and mutant cartilage.
• Analyzed transcriptomic changes using RNA-sequencing.

Main Results:

• V620I and T89I TRPV4 mutations significantly reduced chondrocyte mechanoresponsiveness.
• Gene expression downstream of TRPV4 activation, including endochondral ossification markers, was decreased.
• V620I mutation affected extracellular matrix genes; T89I impacted retinoic acid signaling.
• Disrupted proliferation was observed in both mutant types.

Conclusions:

• Dysfunctional mechanotransduction due to TRPV4 mutations contributes to skeletal dysplasia phenotypes.
• TRPV4 mutations alter chondrocyte responses to mechanical load, impacting skeletal development.
• TRPV4 modulation presents a potential therapeutic strategy for TRPV4-related skeletal disorders.