Objective: To investigate the effect of loss of function of lanosterol synthase( LSS) gene on intestinal function in a mouse model of non-alcoholic fatty liver disease( NAFLD) induced by a high-fat diet． Methods: LSS gene heterozygous knockout C57 mice ( LSS + / －) were established using the CRISRP / Cas9 system．After being fed a high-fat diet with 60% fat content for 6 months，the fat deposition in liver tissues was detected by HE and Oil red O staining，the morphological changes of small intestine tissue were detected by HE staining．The changes in total cholesterol content in intestinal tissue were detected by kits．The gastrointestinal motility function of mice was detected by phenol red paste．The intestinal permeability was detected by Evans blue staining，and the expression of LSS，tight junction protein ( Claudin) -1，Claudin-5，cluster of differentiation 36 ( CD36) ，and Niemann-Pick type C1-like 1 protein ( NPC1L1) proteins in small intestinal tissues were detected by Western blot． Results : The results of HE and Oil red O staining of liver tissues showed that liver fat deposition in LSS gene heterozygous knockout mice was lower than that in wild-type mice in the high-fat diet group．The total cholesterol content in intestinal tis- sue of LSS gene heterozygous knockout mice decreased ( P ＜0. 01) ，but no morphological differences were ob- served between the two groups of mice by HE staining of intestinal tissues．The gastrointestinal motility function of LSS gene heterozygous knockout mice did not show significant changes．The intestinal permeability of LSS gene het- erozygous knockout mice in the high-fat diet group decreased as detected by Evans blue ( P＜0. 05) ．The expres- sion levels of Claudin-5 protein in the intestinal tissue of LSS gene heterozygous knockout mice in the high-fat diet group increased ( P ＜0. 05 ) ，while the expression of LSS protein in the intestinal tissues of LSS heterozygous knockout mice decreased ( P ＜0. 05) ． Conclusion In the NAFLD model induced by a high-fat diet，LSS gene heterozygous knockout reduces liver fat deposition induced by a high-fat diet and improves intestinal barrier function by regulating cholesterol metabolism in intestinal tissues and up-regulating the expression of Claudin-5．

[Abstract] Objective: To explore the expression and regulation mechanism of Dickkopf-1 (DKK1) in head and neck squamous cell carcinoma (HNSCC) tissues. Methods: Based on the TCGA database, the relationship of DKK1 expression in HNSCC tissues and its methylation site with patients’prognosis was analyzed. GO and KEGG gene enrichment method were used to analyze the signaling pathways of DKK1 enrichment. STRING was used to analyze the interaction between DKK1 protein and other proteins. TargetScan was used to analyze the miRNAs that regulate the expression of DKK1, and the transcription factors of DKK1 were analyzed with the TRRUST website. Results: DKK1 gene was highly expressed in HNSCC tissues (P<0.01), and its expression level was significantly correlated with the HPV status, age, pathological grade, and clinical stage of patients (all P<0.05); the prognosis of HNSCC patients with high DKK1 expression was poorer than those with low DKK1 expression (P<0.01). There were 19 methylation sites in DKK1, 12 of which were significantly different between cancer tissues and normal tissues (P<0.05), and 11 sites were significantly related to the prognosis of HNSCC (P<0.05). In addition, miRNA, circRNA, lincRNA and transcription factors, etc. also participated in the regulation of DKK1. A total of 5 DKK1-related PPI networks that may involve in the occurrence, development, invasion and metastasis of HNSCC were obtained. Conclusion: DKK1 is highly expressed in HNSCC tissues and is a risk factor for poor prognosis of HNSCC patients. DKK1 plays an important role in the pathogenesis of HNSCC and is expected to become a potential target for HNSCC treatment.