Mog1 knockout causes cardiac hypertrophy and heart failure by downregulating tbx5-cryab-hspb2 signalling in zebrafish.

AIMS: MOG1 is a small protein that can bind to small GTPase RAN and regulate transport of RNA and proteins between the cytoplasm and nucleus. However, the in vivo physiological role of mog1 in the heart needs to be fully defined. METHODS: Mog1 knockout zebrafish was generated by TALEN. Echocardiography, histological analysis, and electrocardiograms were used to examine cardiac structure and function. RNA sequencing and real-time RT-PCR were used to elucidate the molecular mechanism and to analyse the gene expression. Isoproterenol was used to induce cardiac hypertrophy. Whole-mount in situ hybridization was used to observe cardiac morphogenesis. RESULTS: Mog1 knockout zebrafish developed cardiac hypertrophy and heart failure (enlarged pericardium, increased nppa and nppb expression and ventricular wall thickness, and reduced ejection fraction), which was aggravated by isoproterenol. RNAseq and KEGG pathway analyses revealed the effect of mog1 knockout on the pathways of cardiac hypertrophy, dilatation and contraction. Mechanistic studies revealed that mog1 knockout decreased expression of tbx5, which reduced expression of cryab and hspb2, resulting in cardiac hypertrophy and heart failure. Overexpression of cryab, hspb2 and tbx5 rescued the cardiac oedema phenotype of mog1 KO zebrafish. Telemetry electrocardiogram monitoring showed QRS and QTc prolongation and a reduced heart rate in mog1 knockout zebrafish, which was associated with reduced scn1b expression. Moreover, mog1 knockout resulted in abnormal cardiac looping during embryogenesis because of the reduced expression of nkx2.5, gata4 and hand2. CONCLUSION: Our data identified an important molecular determinant for cardiac hypertrophy and heart failure, and rhythm maintenance of the heart.

Identification of a new adtrp1-tfpi regulatory axis for the specification of primitive myelopoiesis and definitive hematopoiesis.

A genomic variant in the human ADTRP [androgen-dependent tissue factor (TF) pathway inhibitor (TFPI) regulating protein] gene increases the risk of coronary artery disease, the leading cause of death worldwide. TFPI is the TF pathway inhibitor that is involved in coagulation. Here, we report that adtrp and tfpi form a regulatory axis that specifies primitive myelopoiesis and definitive hematopoiesis, but not primitive erythropoiesis or vasculogenesis. In zebrafish, there are 2 paralogues for adtrp (i.e., adtrp1 and adtrp2). Knockdown of adtrp1 expression inhibits the specification of hemangioblasts, as shown by decreased expression of the hemangioblast markers, etsrp, fli1a, and scl; blocks primitive hematopoiesis, as shown by decreased expression of pu.1, mpo, and l-plastin; and disrupts the specification of hematopoietic stem cells (definitive hematopoiesis), as shown by decreased expression of runx1 and c-myb However, adtrp1 knockdown does not affect erythropoiesis during primitive hematopoiesis (no effect on gata1 or h-bae1) or vasculogenesis (no effect on kdrl, ephb2a, notch3, dab2, or flt4). Knockdown of adtrp2 expression does not have apparent effects on all markers tested. Knockdown of adtrp1 reduced the expression of tfpi, and hematopoietic defects in adtrp1 morphants were rescued by tfpi overexpression. These data suggest that the regulation of tfpi expression is one potential mechanism by which adtrp1 regulates primitive myelopoiesis and definitive hematopoiesis.-Wang, L., Wang, X., Wang, L., Yousaf, M., Li, J., Zuo, M., Yang, Z., Gou, D., Bao, B., Li, L., Xiang, N., Jia, H., Xu, C., Chen, Q., Wang, Q. K. Identification of a new adtrp1-tfpi regulatory axis for the specification of primitive myelopoiesis and definitive hematopoiesis.

Cardiac sodium channel regulator MOG1 regulates cardiac morphogenesis and rhythm.

MOG1 was initially identified as a protein that interacts with the small GTPase Ran involved in transport of macromolecules into and out of the nucleus. In addition, we have established that MOG1 interacts with the cardiac sodium channel Nav1.5 and regulates cell surface trafficking of Nav1.5. Here we used zebrafish as a model system to study the in vivo physiological role of MOG1. Knockdown of mog1 expression in zebrafish embryos significantly decreased the heart rate (HR). Consistently, the HR increases in embryos with over-expression of human MOG1. Compared with wild type MOG1 or control EGFP, mutant MOG1 with mutation E83D associated with Brugada syndrome significantly decreases the HR. Interestingly, knockdown of mog1 resulted in abnormal cardiac looping during embryogenesis. Mechanistically, knockdown of mog1 decreases expression of hcn4 involved in the regulation of the HR, and reduces expression of nkx2.5, gata4 and hand2 involved in cardiac morphogenesis. These data for the first time revealed a novel role that MOG1, a nucleocytoplasmic transport protein, plays in cardiac physiology and development.