Skeletal muscle phenotyping of Hippo gene-mutated mice reveals that Lats1 deletion increases the percentage of type I muscle fibers.

The Hippo signal transduction network regulates transcription through Yap/Taz-Tead1-4 in many tissues including skeletal muscle. Whilst transgenic mice have been generated for many Hippo genes, the resultant skeletal muscle phenotypes were not always characterized. Here, we aimed to phenotype the hindlimb muscles of Hippo gene-mutated Lats1-/-, Mst2-/-, Vgll3-/-, and Vgll4+/- mice. This analysis revealed that Lats1-/- mice have 11% more slow type I fibers than age and sex-matched wild-type controls. Moreover, the mRNA expression of slow Myh7 increased by 50%, and the concentration of type I myosin heavy chain is 80% higher in Lats1-/- mice than in age and sex-matched wild-type controls. Second, to find out whether exercise-related stimuli affect Lats1, we stimulated C2C12 myotubes with the hypertrophy agent clenbuterol or the energy stress agent AICAR. We found that both stimulated Lats1 expression by 1.2 and 1.3 fold respectively. Third, we re-analyzed published datasets and found that Lats1 mRNA in muscle is 63% higher in muscular dystrophy, increases by 17-77% after cardiotoxin-induced muscle injury, by 41-71% in muscles during overload-induced hypertrophy, and by 19-21% after endurance exercise when compared to respective controls. To conclude, Lats1 contributes to the regulation of muscle fiber type proportions, and its expression is regulated by physiological and pathological situations in skeletal muscle.

Establishment of a transgenic heterozygous mouse model of ApcMin/+pre-cancerosis of colorectal cancer with p110δmutation / 中国病理生理杂志

[ABSTRACT]AIM:Toestablishatransgenicheterozygousmousemodelofprecancerouslesionsofcolorectal cancer with p110δmutation in the C57BL/6J background for serving the studies on colorectal cancer research mediated by p110δ.METHODS:The transgenic heterozygous mice were generated by crossing in p110δD910A/D910A mouse and ApcMin/+mouse, and the genotype was detected by PCR .Compared with ApcMin/+mice, transgenic heterozygous mice ( ApcMin/+;p110δD910A/D910A)were counted, and the number and size of intestine polyps were analyzed after methylene blue staining . The intestinal tissue structure was assessed by HE staining .RESULTS:The transgenic heterozygous mouse model of pre-cancerous lesions of colorectal cancer with p 110δmutation was established .The number and size of polyps in the transgenic heterozygous mice were declined .CONCLUSION: A transgenic heterozygous mouse model of precancerous lesions of colorectal cancer with p 110δmutation was successfully established .The initial phenotype of intestinal tumors in transgenic mice was observed .This model will greatly contribute to the related research of colorectal cancer in mice .