[Analysis of a child with holoprosencephaly due to variant of SIX3 gene].

OBJECTIVE: To explore the genetic basis of a child with holoprosencephaly. METHODS: Genomic DNA of the child was extracted and subjected to whole exome sequencing. Suspected variant was verified by Sanger sequencing of her family members. RESULTS: Cranial MRI suggested lobulated holoprosencephaly with partial absence of corpus callosum. Genetic testing revealed that she has carried a heterozygous c.517C>G (p.His173Asp) variant of the SIX3 gene, for which both of her parents were of wild type. Based on the American College of Medical Genetics and Genomics guidelines, the c.517C>G variant of SIX3 gene was predicted to be pathogenic (PS2+PM1+PM2+PM5+PP3). CONCLUSION: The SIX3 gene c.517C>G variant probably underlay the multiple malformations in this child. Above finding has enabled her definite diagnosis.

MicroRNA-23 inhibition protects the ischemia/reperfusion injury via inducing the differentiation of bone marrow mesenchymal stem cells into cardiomyocytes.

Recently, miRNA-23 has been illustrated to play an important role in causing myocardial ischemia/reperfusion injury (MIRI), indicated that inhibition of miR-23 could protect the cardiomyocyte from MIRI. However, the underlying mechanism of miR-23 inhibition in alleviating the reperfusion-induced myocardial damage is unclear. Recognizing that the bone marrow mesenchymal stem cells (BMSCs) have the potential for pluripotent differentiation into myocardial cells, we therefore hypothesis that the BMSCs are involved in the process of miR-23 alleviating IRI. For verification, the BMSCs was established firstly and confirmed by the immunofluorescence assay and flow cytometry analysis. As results revealed that BMSCs were positive for CD44 which was known for BMSC markers, and negative expression for CD45, indicating that the BMSCs was successfully established in our work. Subsequently, we have investigated the effect of miR-23 on the expression of hyaluronan synthase-2 (Has2), a critical gene during heart morphogenesis. Results obtained by the Western-blot and qRT-PCR assay displayed that the levels of Has2 in the BMSCs treated by miR-23 inhibitor was significantly up-regulated than that of control group. Furthermore, the effect of miR-23 on promoting the transformation of BMSCs into myocardial cells was investigated. As demonstrated by the results that the expression level of the cardiac markers in BMSCs transfected with miR-23 inhibitor was remarkably elevated, indicating that inhibition of miR-23 exactly facilitated to the transformation of BMSCs into myocardial cells. The underlying mechanisms experiments showed that the Wnt1, TCF4, and the ß-catenin could be significantly elevated by treating with miR-23 inhibitor, suggesting that the activation of Wnt pathway has played a significant role in that process. Finally, the in vivo IRI antagonism effect of miR-23 inhibition was studied and results displayed that the myocardium lesions of these IR rats could be significantly recovered by treating with miR-23 inhibitor.