Altered splicing factor and alternative splicing events in a mouse model of diet- and polychlorinated biphenyl-induced liver disease

Reduced transcriptome analysis in zebrafish uncovers disruptors of spliceosome and ribosome biosynthesis

Abnormal biosynthesis of spliceosomes and ribosomes can lead to their dysfunction, which in turn disrupts protein synthesis and results in various diseases. While genetic factors have been extensively studied, our understanding of how environmental compounds interfere with spliceosome and ribosome biosynthesis remains limited. In the present study, we employed a Reduced Transcriptome Analysis (RTA) approach, integrating large-scale transcriptome data sets of zebrafish and compiling a specific zebrafish gene panel focusing on the spliceosome and ribosome, to elucidate the potential disruptors targeting their biosynthesis. Transcriptomic data sets for 118 environmental substances and 1400 related gene expression profiles were integrated resulting in 513 exposure signatures. Among these substances, several categories including PCB126, transition metals Lanthanum (La) and praseodymium (Pr), heavy metals Cd2+ and AgNO3 and atrazine were highlighted for inducing the significant transcriptional alterations. Furthermore, we found that the transcriptional patterns were distinct between categories, yet overlapping patterns were generally observed within each group. For instance, over 82 % differentially expressed ribosomal genes were shared between La and Pr within the equivalent concentration range. Additionally, transcriptional complexities were also evident across various organs and developmental stages of zebrafish, with notable differences in the inhibition of the transcription of various spliceosome subunits. Overall, our results provide novel insights into the understanding of the adverse effects of environmental compounds, thereby contributing to their environmental risk assessments.

Chronic Aroclor 1260 exposure alters the mouse liver proteome, selenoproteins, and metals in steatotic liver disease

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) continues to increase due in part to the obesity epidemic and to environmental exposures to metabolism disrupting chemicals. A single gavage exposure of male mice to Aroclor 1260 (Ar1260), an environmentally relevant mixture of non-dioxin-like polychlorinated biphenyls (PCBs), resulted in steatohepatitis and altered RNA modifications in selenocysteine tRNA 34 weeks post-exposure. Unbiased approaches identified the liver proteome, selenoproteins, and levels of 25 metals. Ar1260 altered the abundance of 128 proteins. Enrichment analysis of the liver Ar1260 proteome included glutathione metabolism and translation of selenoproteins. Hepatic glutathione peroxidase 4 (GPX4) and Selenoprotein O (SELENOO) were increased and Selenoprotein F (SELENOF), Selenoprotein S (SELENOS), Selenium binding protein 2 (SELENBP2) were decreased with Ar1260 exposure. Increased copper, selenium (Se), and zinc and reduced iron levels were detected. These data demonstrate that Ar1260 exposure alters the (seleno)proteome, Se, and metals in MASLD-associated pathways.

The m6A reader IGF2BP1 attenuates the stability of RPL36 and cell proliferation to mediate benzene hematotoxicity by recognizing m6A modification

Benzene exposure leads to hematotoxicity, and epigenetic modification is considered to be a potential mechanism of benzene pathogenesis. As a newly discovered post-transcriptional modification, the roles of N6-methyladenosine (m6A) in benzene hematotoxicity are still unclear. m6A can only exert its gene regulatory function after being recognized by m6A reading proteins. In this study, we found that the expression of m6A reader IGF2BP1 decreased in benzene poisoning workers and in 20 μM benzene metabolite 1,4-BQ-treated AHH-1 cells. Further overexpression of IGF2BP1 in mice alleviated 50 ppm benzene-induced hematopoietic damage, suggesting that IGF2BP1 plays a critical role in benzene hematotoxicity. Next, we examined transcriptome-wide m6A methylation in vitro to search for target genes of IGF2BP1. We found that benzene metabolite 1,4-BQ treatment altered the m6A methylation levels of various genes. The comprehensive analysis of mRNA expression and m6A methylation uncovered that the hypomethylated Ribosomal Protein L36 (RPL36) and its consequent reduced expression impaired cell proliferation. Mechanically, m6A modification reduced RNA stability to down-regulate RPL36 expression. Moreover, overexpression of IGF2BP1 relieved RPL36 reduction and cell proliferation inhibition caused by benzene in vitro and in vivo by directly binding with RPL36 mRNA. In conclusion, the m6A reader IGF2BP1 attenuates the stability of RPL36 and cell proliferation to mediate benzene hematotoxicity by recognizing m6A modification. IGF2BP1 and RPL36 may be key molecules and potential therapeutic targets for benzene hematotoxicity.