Ercc2/Xpd deficiency results in failure of digestive organ growth in zebrafish with elevated nucleolar stress

Mitochondrial Mayhem: How cigarette smoke induces placental dysfunction through MMS19 degradation

Cigarette smoke (CS) has detrimental effects on placental growth and embryo development, but the underlying mechanisms remain unclear. This study aims to investigate the impact of CS on trophoblast cell proliferation and regulated cell death (RCD) by examining its interference with iron-sulfur cluster (ISC) proteins and the CIA pathway. Exposure to CS disrupted the cytosolic ISC assembly (CIA) pathway, downregulated ISC proteins, and decreased ISC maturation in the placenta of rats exposed to passive smoking. Studies using HTR-8/Sneo cells demonstrated that cigarette smoke extract (CSE) inhibits trophoblast proliferation, activates autophagy, and induces apoptosis by impairing the CIA pathway and ISC proteins. Molecular docking analysis revealed that nicotine and nicotyrine bind to and promote the autophagic-dependent degradation of MMS19, a key component of the CIA complex. MMS19 KD led to the autophagic degradation of several ISC proteins involved in DNA damage repair and mitochondrial respiratory function, thereby inhibiting cell proliferation. Additionally, MMS19 deficiency resulted in mitochondrial fragmentation, ROS accumulation, and the induction of autosis and apoptosis. Transcriptome analysis indicated that dysregulation of the SMAD pathway mediates mitochondrial damage induced by MMS19 KD. Analysis of placental tissues from maternal smokers further confirmed the disruption of ISC proteins and the SMAD pathway. This study suggests that disruption of the CIA pathway and ISC proteins contributes to placental maldevelopment induced by CS. Targeting the MMS19-SMAD pathway may offer a potential strategy to mitigate adverse pregnancy outcomes caused by CS.

Tcap deficiency impedes striated muscle function and heart regeneration with elevated ROS and autophagy

Telethonin/titin-cap (TCAP) encodes a Z-disc protein that plays important roles in sarcomere/T-tubule interactions, stretch-sensing and signaling. Mutations in TCAP are associated with muscular dystrophy and cardiomyopathy; however, the complete etiology and its roles in myocardial infarction and regeneration are not fully understood. Here, we generated tcap gene knockout zebrafish with CRISPR/Cas9 technology and observed muscular dystrophy-like phenotypes and abnormal mitochondria in skeletal muscles. The stretch-sensing ability was inhibited in tcap-/- mutants. Moreover, Tcap deficiency led to alterations in cardiac morphology and function as well as increases in reactive oxygen species (ROS) and mitophagy. In addition, the cardiac regeneration and cardiomyocyte proliferation ability of tcap-/- mutants were impaired, but these impairments could be rescued by supplementation with ROS scavengers or autophagy inhibitors. Overall, our study demonstrates the essential roles of Tcap in striated muscle function and heart regeneration. Additionally, elevations in ROS and autophagy may account for the phenotypes resulting from Tcap deficiency and could serve as novel therapeutic targets for muscular dystrophy and cardiomyopathy.

Embryonic dexamethasone exposure exacerbates hepatic steatosis and APAP-mediated liver injury in zebrafish

Dexamethasone (DXMS), a synthetic glucocorticoid, is known for its pharmacological effects on anti-inflammation, stress response enhancement and immune suppression, and has been widely used to treat potential premature delivery and related diseases. However, emerging evidence has shown that prenatal DXMS exposure leads to increased susceptibility to multiple diseases. In the present study, we used zebrafish as a model to study the effects of embryonic DXMS exposure on liver development and disease. We discovered that embryonic DXMS exposure upregulated the levels of total cholesterol and triglycerides in the liver, increased the glycolysis process and ultimately caused hepatic steatosis in zebrafish larvae. Furthermore, DXMS exposure exacerbated hepatic steatosis in a zebrafish model of fatty liver disease. In addition, we showed that embryonic DXMS exposure worsened liver injury induced by paracetamol (N-acetyl-p-aminophenol, APAP), increased the infiltration of macrophages and neutrophils, and promoted the expression of inflammatory factors, leading to impeded liver regeneration. Taken together, our results provide new evidence that embryonic DXMS exposure exacerbates hepatic steatosis by activating glycolytic pathway, aggravates APAP-induced liver damage and impeded regeneration under a persistent inflammation, calling attention to DXMS administration during pregnancy with probable clinical implications for offspring.

A novel gene-trap line reveals the dynamic patterns and essential roles of cysteine and glycine-rich protein 3 in zebrafish heart development and regeneration

Mutations in cysteine and glycine-rich protein 3 (CSRP3)/muscle LIM protein (MLP), a key regulator of striated muscle function, have been linked to hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) in patients. However, the roles of CSRP3 in heart development and regeneration are not completely understood. In this study, we characterized a novel zebrafish gene-trap line, gSAIzGFFM218A, which harbors an insertion in the csrp3 genomic locus, heterozygous fish served as a csrp3 expression reporter line and homozygous fish served as a csrp3 mutant line. We discovered that csrp3 is specifically expressed in larval ventricular cardiomyocytes (CMs) and that csrp3 deficiency leads to excessive trabeculation, a common feature of CSRP3-related HCM and DCM. We further revealed that csrp3 expression increased in response to different cardiac injuries and was regulated by several signaling pathways vital for heart regeneration. Csrp3 deficiency impeded zebrafish heart regeneration by impairing CM dedifferentiation, hindering sarcomere reassembly, and reducing CM proliferation while aggravating apoptosis. Csrp3 overexpression promoted CM proliferation after injury and ameliorated the impairment of ventricle regeneration caused by pharmacological inhibition of multiple signaling pathways. Our study highlights the critical role of Csrp3 in both zebrafish heart development and regeneration, and provides a valuable animal model for further functional exploration that will shed light on the molecular pathogenesis of CSRP3-related human cardiac diseases.

Embryonic Amoxicillin Exposure Has Limited Impact on Liver Development but Increases Susceptibility to NAFLD in Zebrafish Larvae

Amoxicillin is commonly used in clinical settings to target bacterial infection and is frequently prescribed during pregnancy. Investigations into its developmental toxicity and effects on disease susceptibility are not comprehensive. Our present study examined the effects of embryonic amoxicillin exposure on liver development and function, especially the effects on susceptibility to non-alcoholic fatty liver disease (NAFLD) using zebrafish as an animal model. We discovered that embryonic amoxicillin exposure did not compromise liver development, nor did it induce liver toxicity. However, co-treatment of amoxicillin and clavulanic acid diminished BESP expression, caused bile stasis and induced liver toxicity. Embryonic amoxicillin exposure resulted in elevated expression of lipid synthesis genes and exacerbated hepatic steatosis in a fructose-induced NAFLD model, indicating embryonic amoxicillin exposure increased susceptibility to NAFLD in zebrafish larvae. In summary, this research broadens our understanding of the risks of amoxicillin usage during pregnancy and provides evidence for the impact of embryonic amoxicillin exposure on disease susceptibility in offspring.