RESUMO
Objective:To explore the mechanism of highly expressed primary cilia in tibial growth plate chondrocytes accelerating chondrocytes differentiation in young rats with chronic renal failure (CRF).Methods:Forty male 4-week-old SD rats weighing (98±3) g were randomly divided into control group (intragastric administration with distilled water, n=20) and CRF group (intragastric administration with adenine suspension 150 mg·kg -1·d -1, n=20). All the young rats were sacrificed after continuous gavage for 6 weeks. The length of the growth plate was measured with histological sections. Immunofluorescence (IF) was used to detect the expression rate of primary cilia and the level of β-catenin, the key protein of Wnt/β-catenin signaling pathway in tibial growth plate chondrocytes. Chondrocytes isolated from growth plate in two groups were cultured in vitro to P3 generation, and the expression rate of primary cilia in chondrocytes, the levels of Indian hedgehog (IHH) and glycogen synthase kinase 3β (GSK3β) were detected by IF. Co-immunoprecipitation was used to detect the relationship between IHH and GSK3β. Results:Compared with the control group, the relative length of the growth plate was shorter in histological sections [(0.51±0.11) vs (1.00±0.08), t=16.11, P<0.001], the expression rate of primary cilia was higher [(26.3±5.5)% vs (7.6±1.9)%, t=14.37, P<0.001], and the level of β-catenin increased [(7.1±2.0) scores vs (3.6±1.0) scores, t=7.10, P<0.001] in CRF group. In vitro, the expression rate of primary cilia was higher in CRF group chondrocytes [(31.4±8.2)% vs (12.5±3.1)%, t=9.64, P<0.001] than that in control group. The level of IHH in CRF group increased than that in control group [(1 360±270) vs (310±84), t=16.61, P<0.001]. There was no significant difference in GSK3β level of chondrocytes between the two groups [(850±195) vs (780±140), t=1.30, P=0.200]. There was a direct interaction between IHH and GSK3β in CRF group chondrocytes. Conclusions:The expression levels of primary cilia and related protein IHH increase in tibial growth plate chondrocytes of CRF young rats. The IHH protein plays a direct interaction with GSK3β protein, Wnt/β-catenin signaling pathway antagonist, which leads to the activation of Wnt/β-catenin signaling pathway and final accelerated differentiation of chondrocytes. The rapid differentiation of chondrocytes causes the closing trend of growth plate.