Heinonen J, Zhang F-P, Surmann-Schmitt C, Honkala S, Stock M, Poutanen M, Säämänen A-M
Institute of Biomedicine, University of Turku, Turku, Finland.
Institute of Biomedicine, University of Turku, Turku, Finland; Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland.
Osteoarthritis Cartilage. 2017 Jul;25(7):1132-1142. doi: 10.1016/j.joca.2017.03.010. Epub 2017 Mar 18.
The role of Snorc, a novel cartilage specific transmembrane proteoglycan, was studied during skeletal development using two Snorc knockout mouse models. Hypothesizing that Snorc, like the other transmembrane proteoglycans, may be a coreceptor, we also studied its interaction with growth factors.
Skeletal development was studied in wild type (WT) and Snorc knockout mice during postnatal development by whole mount staining, X-ray imaging, histomorphometry, immunohistochemistry and qRT-PCR. Snorc promoter activity was studied by applying the LacZ reporter expressed by the targeting construct. Slot blot binding and cell proliferation assays were used to study the interaction of Snorc with several growth factors.
Snorc expression was localized in the knee epiphyses especially to the prehypertrophic chondrocytes delineating the cartilage canals and secondary ossification center (SOC). Snorc was demonstrated to have a glycosaminoglycan independent affinity to FGF2 and it inhibited FGF2 dependent cell growth of C3H101/2 cells. In Snorc deficient mice, SOCs in knee epiphyses were smaller, and growth plate (GP) maturation was disturbed, but total bone length was not affected. Central proliferative and hypertrophic zones were enlarged with higher extracellular matrix (ECM) volume and rounded chondrocyte morphology at postnatal days P10 and P22. Increased levels of Ihh and Col10a1, and reduced Mmp13 mRNA expression were observed at P10.
These findings suggest a role of Snorc in regulation of chondrocyte maturation and postnatal endochondral ossification. The interaction identified between recombinant Snorc core protein and FGF2 suggest functions related to FGF signaling.
利用两种Snorc基因敲除小鼠模型，研究新型软骨特异性跨膜蛋白聚糖Snorc在骨骼发育过程中的作用。鉴于推测Snorc可能与其他跨膜蛋白聚糖一样是一种共受体，我们还研究了它与生长因子的相互作用。
通过整体染色、X射线成像、组织形态计量学、免疫组织化学和qRT-PCR，研究野生型（WT）和Snorc基因敲除小鼠出生后发育过程中的骨骼发育情况。通过应用靶向构建体表达的LacZ报告基因研究Snorc启动子活性。采用狭缝印迹结合和细胞增殖试验研究Snorc与几种生长因子的相互作用。
Snorc表达定位于膝关节骨骺，尤其定位于勾勒软骨管和二级骨化中心（SOC）的前肥大软骨细胞。已证明Snorc对FGF2具有不依赖糖胺聚糖的亲和力，并抑制C3H101/2细胞的FGF2依赖性细胞生长。在Snorc基因缺陷小鼠中，膝关节骨骺的SOC较小，生长板（GP）成熟受到干扰，但总骨长度未受影响。在出生后第10天和第22天，中央增殖区和肥大区扩大，细胞外基质（ECM）体积增加，软骨细胞形态呈圆形。在第10天观察到Ihh和Col10a1水平升高，Mmp mRNA表达降低。
这些发现表明Snorc在软骨细胞成熟和出生后软骨内骨化的调节中发挥作用。重组Snorc核心蛋白与FGF2之间的相互作用表明其与FGF信号传导相关的功能。
