Hypertrophy of the ligamentum flavum (HLF) is one of the common causes of lumbar spinal stenosis (LSS). The key molecules and mechanisms responsible for HLF remain unclear. Here, we used an integrated transcriptome and proteomics analysis of human ligamentum flavum (LF), and subsequent immunohistochemistry and real-time PCR assays, to show upregulation of CRLF1 to be the dominant response to HLF. TGF-β1 significantly increased mRNA expression of CRLF1 through SMAD3 pathway. CRLF1 enhanced LF fibrosis via ERK signaling pathway at the post-transcriptional level and was required for the pro-fibrotic effect of TGF-β1. Knockdown of CRLF1 was shown here to reduce fibrosis caused by inflammatory cytokines and mechanical stress. Furthermore, we found that bipedal standing posture can cause HLF and upregulation of CRLF1 expression in mice LF. Overexpression of CRLF1 was indicated to cause HLF in vivo, whereas CRLF1 knockdown impeded the formation of HLF in bipedal standing mice. These results revealed a crucial role of CRLF1 in LF hypertrophy. We propose that inhibition of CRLF1 is a potential therapeutic strategy to treat HLF.

黄韧带肥大（HLF）是腰椎管狭窄（LSS）的常见原因之一。导致HLF的关键分子和机制仍不清楚。在这里，我们使用了人类黄韧带（LF）的完整转录组和蛋白质组学分析，以及随后的免疫组化和实时PCR分析，以显示CRLF1的上调是对HLF的主要反应。TGF-β1通过SMAD3途径显着增加CRLF1的mRNA表达。CRLF1在转录后水平通过ERK信号通路增强LF纤维化，并且是TGF-β1促纤维化作用所必需的。此处所示的CRLF1基因敲低可减少由炎性细胞因子和机械应力引起的纤维化。此外，我们发现两足动物的站立姿势可导致小鼠LF中的HLF和CRLF1表达上调。体内，而CRLF1敲低阻碍了两足站立小鼠中HLF的形成。这些结果揭示了CRLF1在LF肥大中的关键作用。我们建议抑制CRLF1是治疗HLF的潜在治疗策略。