All Knees

It’s tough, it’s rubbery, it’s your cartilage. Your joints contain two types: articular cartilage, which covers the ends of your bones, and growth-plate cartilage, which forms the ends of long bones. Both comprise cells called chondrocytes. How these types of cartilage develop isn’t clear. Researchers now investigate in mice genetically engineered with fluorescently-tagged NFATc1 – a protein which when inactivated interferes with cartilage development. Using fluorescent microscopy of developing mouse knee joints, they found NFATc1-containing cells (progenitors) matured into articular chondrocytes but not growth-plate chondrocytes. NFATc1-containing progenitors also matured into cells that contribute to the joint lining, ligaments and developing kneecap (pictured, green). Analysing the RNA of articular chondrocytes revealed that NFATc1 levels dropped as the cells matured. Reducing NFATc1 levels in progenitors triggered articular cartilage formation while increasing levels blocked this from happening. NFATc1 is therefore vital for articular — but not growth-plate — cartilage development.

Written by Lux Fatimathas

Lux Fatimathas

Writer

Having pursued science through a career in research, communications and publishing, she is currently a writer and editor for a healthcare marketing agency and also juggles freelance science writing.

• Image from work by Fan Zhang and Yuanyuan Wang, and colleagues
• Xuanwu Hospital, Capital Medical University, China; National Clinical Research Center for Geriatric Diseases, China
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in eLife, February 2023