Project description:To explore the genetic cause of a Chinese woman with fetal hydrocephalus X-linked hydrocephalus (XLH), a genetic disorder, has an incidence of 1/30,000 male births. The great proportion of XLH is ascribed to loss of function mutations of L1 cell adhesion molecule gene (L1CAM), but silent mutations in L1CAM with pathogenic potential were rare, and were usually ignored especially in WES detection. In the present study, we describe a novel silent L1CAM mutation in a Chinese pregnant woman reporting continuous five times pregnancies with fetal hydrocephalus. After fetal blood sampling, we found c.453G>T (p.Gly151=) in L1CAM gene of the fetus by whole exome sequencing (WES), RT-PCR of the mRNA from cord blood mononuclear cells and subsequent sequence analysis identified the mutation created a potential 5' splice site consensus sequence, which would result in an in-frame deletion of 72 bp from exon 5 and 24 amino acids of the L1CAM protein. Heterozygous mutations were confirmed in analyzing DNA and mRNA from peripheral blood mononuclear cells of the woman, and, a severe L1 syndrome was confirmed by fetal ultrasound scan and MRI. Our study first indicated c.453G>T (p.Gly151=) in L1CAM could be disease causing for hydrocephalus, which would aid in genetic counseling for the prenatal diagnosis of hydrocephalus. Meanwhile, it suggested some silent mutations detected in WES should not be ignored, splicing predictions of these mutations were necessary.
Project description:We studies on Trim71 regulates mouse embryonic stem cells by identifying the transcriptome-wide RNA targets of Trim71. Moreover, through inhibiting specific Trim71:mRNA interactions, we determined how Trim71 modulate miRNA activity in mouse embryonis cell cells
Project description:Mutations in TRIM71’s RNA-binding domain leads to congenital hydrocephalus in human patients and a TRIM71 mutant mouse model (Trim71R595H/+). Additionally, homozygous Trim71R595H/R595H mice phenocopy the neural tube defects and premature neural differentiation observed in TRIM71-KO mice. As RNA-Seq analyses revealed that TRIM71-KO mESC are poised for neural differentiation, we aimed to also examine the transcriptomes of TRIM71R595H/R595H and TRIM71R595H/+ mESC. Both TRIM71-KO and TRIM71R595H/R595H mutations in mESC result in transcriptomic changes with similar patterns, when compared to control mESC. Similar to TRIM71-KO, the transcriptome of Trim71R595H/R595H mESC indicates a poised state of mutated mESC towards neural differentiation.
Project description:Congenital hydrocephalus (CH) is a major cause of childhood morbidity. Mono-allelic mutations in Trim71, a conserved stem-cell-specific RNA-binding protein, cause CH; however, the molecular basis for pathogenesis mediated by these mutations remains unknown. Here, using mouse embryonic stem cells as a model, we reveal that the mouse R783H mutation (R796H in human) alters Trim71's mRNA substrate specificity and leads to accelerated stem-cell differentiation and neural lineage commitment. Mutant Trim71, but not wild-type Trim71, binds Lsd1 (Kdm1a) mRNA and represses its translation. Specific inhibition of this repression or a slight increase of Lsd1 in the mutant cells alleviates the defects in stem cell differentiation and neural lineage commitment. These results determine a functionally relevant target of the CH-causing Trim71 mutant that can potentially be a therapeutic target and provide molecular mechanistic insights into the pathogenesis of this disease.
