The extracellular matrix molecule Tenascin-C (TNC) promotes cancer and chronic inflammation by multiple mechanisms. Recently, TNC was shown to promote an immune suppressive tumor microenvironment (TME) through binding soluble chemoattracting factors, thus retaining leukocytes in the stroma. TNC also binds to fibronectin (FN) and other molecules, raising the question of a potential common TNC binding mechanism. By sequence comparison of two TNC-interacting domains in FN, the fifth (FN5) and thirteenth (FN13) fibronectin type III domains we identified a MAtrix REgulating MOtif “MAREMO” or M-motif that is highly conserved amongst vertebrates. By sequence analysis, structural modeling and functional analysis we found also putative M-motifs in TNC itself. We showed by negative staining electron microscopic imaging that the M-motif in FN mediates interactions with FN as well as with TNC. We generated two M-motif mimetic peptides P5 and P13 resembling the M-motif in FN5 and FN13, respectively. By using structural information we modelled binding of these M-motif mimetics revealing a putative MAREMO binding site MBS in FN5 and TN3, respectively overlapping with the M-motif. We further demonstrated that the M-motif mimetic peptides blocked several functions of TNC, such as binding of TNC to FN, cell rounding on a mixed FN/TNC substratum, FN matrix expression and subsequent assembly, TNC-induced signaling and gene expression, TNC chemokine binding and dendritic cell retention, thus providing novel opportunities to inhibit TNC actions. Our results suggest that targeting the MAREMO/MBS interaction could be exploited for reducing inflammation and matrix functions in cancer and fibrosis.

细胞外基质分子 Tenascin-C (TNC) 通过多种机制促进癌症和慢性炎症。最近，TNC 被证明通过结合可溶性化学吸引因子来促进免疫抑制性肿瘤微环境 (TME)，从而将白细胞保留在基质中。TNC 还与纤连蛋白 (FN) 和其他分子结合，提出了潜在的常见 TNC 结合机制的问题。通过 FN 中两个 TNC 相互作用域的序列比较，第五个 (FN5) 和第十三个 (FN13) 纤连蛋白 III 型域，我们确定了一个在脊椎动物中高度保守的矩阵调节基序“MAREMO”或 M-基序。通过序列分析、结构建模和功能分析，我们还在 TNC 本身中发现了推定的 M 基序。我们通过负染色电子显微镜成像表明，FN 中的 M 基序介导与 FN 以及 TNC 的相互作用。我们分别生成了两个类似于 FN5 和 FN13 中的 M 基序的 M 基序模拟肽 P5 和 P13。通过使用结构信息，我们模拟了这些 M-motif 模拟物的结合，揭示了 FN5 和 TN3 中推定的 MAREMO 结合位点 MBS，分别与 M-motif 重叠。我们进一步证明了 M 基序模拟肽阻断了 TNC 的几种功能，例如 TNC 与 FN 的结合、混合 FN/TNC 培养基上的细胞变圆、FN 基质表达和随后的组装、TNC 诱导的信号传导和基因表达、TNC趋化因子结合和树突状细胞保留，从而为抑制 TNC 作用提供了新的机会。