Chondrocytes in the resting zone of the growth plate are maintained in a Wnt-inhibitory environment

SA Hallett, Y Matsushita, W Ono, N Sakagami… - Elife, 2021 - elifesciences.org
SA Hallett, Y Matsushita, W Ono, N Sakagami, K Mizuhashi, N Tokavanich, M Nagata…
Elife, 2021elifesciences.org
Chondrocytes in the resting zone of the postnatal growth plate are characterized by slow cell
cycle progression, and encompass a population of parathyroid hormone-related protein
(PTHrP)-expressing skeletal stem cells that contribute to the formation of columnar
chondrocytes. However, how these chondrocytes are maintained in the resting zone
remains undefined. We undertook a genetic pulse-chase approach to isolate slow cycling,
label-retaining chondrocytes (LRCs) using a chondrocyte-specific doxycycline-controllable …
Chondrocytes in the resting zone of the postnatal growth plate are characterized by slow cell cycle progression, and encompass a population of parathyroid hormone-related protein (PTHrP)-expressing skeletal stem cells that contribute to the formation of columnar chondrocytes. However, how these chondrocytes are maintained in the resting zone remains undefined. We undertook a genetic pulse-chase approach to isolate slow cycling, label-retaining chondrocytes (LRCs) using a chondrocyte-specific doxycycline-controllable Tet-Off system regulating expression of histone 2B-linked GFP. Comparative RNA-seq analysis identified significant enrichment of inhibitors and activators for Wnt signaling in LRCs and non-LRCs, respectively. Activation of Wnt/β-catenin signaling in PTHrP+ resting chondrocytes using Pthlh-creER and Apc-floxed allele impaired their ability to form columnar chondrocytes. Therefore, slow-cycling chondrocytes are maintained in a Wnt-inhibitory environment within the resting zone, unraveling a novel mechanism regulating maintenance and differentiation of PTHrP+ skeletal stem cells of the postnatal growth plate.
eLife