Compound heterozygous variations in IARS1 cause recurrent liver failure and growth retardation in a Chinese patient: a case report.

BACKGROUND: Aminoacyl-tRNA synthetases (ARSs) are enzymes responsible for attaching amino acids to tRNA, which enables protein synthesis. Mutations in isoleucyl-tRNA synthetase (IARS1) have recently been reported to be a genetic cause for growth retardation, intellectual disability, muscular hypotonia, and infantile hepatopathy (GRIDHH). CASE PRESENTATION: In this study, we reported an additional case of compound heterozygous missense variations c.701 T > C (p.L234P) and c.1555C > T (p.R519C) in IARS1, which were identified using medical exome sequencing; c.701 T > C (p.L234P) was a novel variant, and c.1555C > T (p.R519C) was found in GnomAD. Unlike other reported patients, this individual presented prominently with recurrent liver failure, which led to her death at an early age of 19 months. She also had significant growth retardation, muscular hypotonia, chubby and flabby face, recurrent loose stools, and abnormal brain computed tomography (CT), while zinc deficiency and hearing loss were not present. Studies in zebrafish embryo modeling recapitulated some of the key phenotypic traits in embryo development, neurodevelopment, liver development, and myogenesis, demonstrating that these variations caused a loss of gene function in IARS1. CONCLUSIONS: We have found a novel mutation point c.701 T > C (p.L234P) in IARS1. Compound heterozygous mutations of c.701 T > C (p.L234P) and c.1555C > T (p.R519C) in IARS1 are pathogenic, which can cause GRIDHH in child.

Clock1a affects mesoderm development and primitive hematopoiesis by regulating Nodal-Smad3 signaling in the zebrafish embryo.

Circadian clock and Smad2/3/4-mediated Nodal signaling regulate multiple physiological and pathological processes. However, it remains unknown whether Clock directly cross-talks with Nodal signaling and how this would regulate embryonic development. Here we show that Clock1a coordinated mesoderm development and primitive hematopoiesis in zebrafish embryos by directly up-regulating Nodal-Smad3 signaling. We found that Clock1a is expressed both maternally and zygotically throughout early zebrafish development. We also noted that Clock1a alterations produce embryonic defects with shortened body length, lack of the ventral tail fin, or partial defect of the eyes. Clock1a regulates the expression of the mesodermal markers ntl, gsc, and eve1 and of the hematopoietic markers scl, lmo2, and fli1a Biochemical analyses revealed that Clock1a stimulates Nodal signaling by increasing expression of Smad2/3/4. Mechanistically, Clock1a activates the smad3a promoter via its E-box1 element (CAGATG). Taken together, these findings provide mechanistic insight into the role of Clock1a in the regulation of mesoderm development and primitive hematopoiesis via modulation of Nodal-Smad3 signaling and indicate that Smad3a is directly controlled by the circadian clock in zebrafish.

Polyethylene glycol modification decreases the cardiac toxicity of carbonaceous dots in mouse and zebrafish models.

AIM: Carbonaceous dots (CDs), which have been used for diagnosis, drug delivery and gene delivery, are accumulated in heart at high concentrations. To improve their biocompatibility, polyethylene glycol-modified CDs (PEG-CDs) were prepared. In this study we compared the cardiac toxicity of CDs and PEG-CDs in mouse and zebrafish models. METHODS: Mice were intravenously treated with CDs (size: 4.9 nm, 5 mg·kg(-1)·d(-1)) or PEG-CDs (size: 8.3 nm, 5 mg·kg(-1)·d(-1)) for 21 d. Their blood biochemistry indices, ECG, and histological examination were examined for evaluation of cardiac toxicity. CDs or PEG-CDs was added in incubator of cmlc2 transgenic Zebrafish embryos at 6 hpf, and the shape and size of embryos' hearts were observed at 48 hpf using a fluorescent microscope. Furthermore, whole-mount in situ hybridization was used to examine the expression of early cardiac marker gene (clml2) at 48 hpf. RESULTS: Administration of CDs or PEG-CDs in mice caused mild, but statistically insignificant reduction in serum creatine kinase (CK) and lactate dehydrogenase (LDH) levels detected at 7 d, which were returned to the respective control levels at 21 d. Neither CDs nor PEG-CDs caused significant changes in the morphology of heart cells. Administration of CDs, but not PEG-CDs, in mice caused marked increase of heart rate. Both CDs and PEG-CDs did not affect other ECG parameters. In the zebrafish embryos, addition of CDs (20 µg/mL) caused heart development delay, whereas addition of CDs (80 µg/mL) led to heart malformation. In contrast, PEG-CDs caused considerably small changes in heart development, which was consistent with the results from the in situ hybridization experiments. CONCLUSION: CDs causes greater cardiac toxicity, especially regarding heart development. Polyethylene glycol modification can attenuate the cardiac toxicity of CDs.

[Roles of miR-15b in endothelial cell function and their relevance to vascular diseases].

MicroRNAs (miRNAs) are noncoding RNAs with a short length of about 22 nucleotides. As major modulators participating in RNA interference, they affect cellular behaviors by regulating the expression of diverse genes at post-transcriptional levels. miR-15b is a member of the miR-15/16 family, which is broadly expressed in major tissues and specially enriched in the endovascular system of human beings. miR-15/16 affects cellular proliferation, apoptosis, invasion and angiogenesis. In this review, we summarize the role and the underlying mechanism of miR-15b as well as other miR-15/16 family members in different cells, especially in endothelial cells. We focus on the diverse roles of miR-15b in the occurrence, progression and prognosis of vascular diseases, with particular emphasis on preeclampsia, a hypertensive disorder related to endovascular dysfunction in the placenta.

[Initial study on zili functions to the development of the germ layers during zebrafish early embryogenesis].

OBJECTIVE: To study the role for piwil2 gene (zili) in the development of the ectoderm, mesoderm and endoderm during early embryogenesis of zebrafish. METHODS: zili morpholino antisense oligonucleotide and 5 mis-pair control morpholino were used in this study. zili was cloned into expression vector. zili mRNA was synthesized in vitro. The antisense RNA probes of gsc, evel and sox17 were synthesized. zili-MO, zili-cMO and zili mRNA was microinjected into one-cell embryos, respectively. Whole-mount in situ hybridization was used to monitor the expressions of marker genes. RESULTS: Microinjection of zili-MO, which knocked down the expression of zili, downregulated the expression of the ectodermal and mesodermal marker gene gsc, promoting the expression of the ectodermal marker gene evel and resulting in the decrease of endodermal cell expressed sox17. The overexpression of zili, promoting the expression of gsc, inhibiting the expression of eve1 and resulting in the decrease of endodermal cell expressed sox17 were observed after microinjection of zili-mRNA. CONCLUSION: zili might have some effect on the formation of the ectoderm, mesoderm and endoderm during early embryogenesis and might be important for normal embryonic development.