c-Jun N-terminal kinase 1 (JNK1) phosphorylates OTX2 transcription factor that regulates early retinal development

BACKGROUND

The transcription factor orthodenticle homeobox 2 (OTX2) has critical functions in brain and eye development, and its mutations in humans are related to retinal diseases, such as ocular coloboma and microphthalmia. However, the regulatory mechanisms of OTX2 are poorly identified.

OBJECTIVE

The identification of JNK1 as an OTX2 regulatory protein through the protein interaction and phosphorylation.

METHODS

To identify the binding partner of OTX2, we performed co-immunoprecipitation and detected with a pooled antibody that targeted effective kinases. The protein interaction between JNK1 and OTX2 was identified with the co-immunoprecipitation and immunocytochemistry. In vivo and in vitro kinase assay of JNK1 was performed to detect the phosphorylation of OTX2 by JNK1.

RESULTS

JNK1 directly interacted with OTX2 through the transactivation domain at the c-terminal region. The protein-protein interaction and co-localization between JNK1 and OTX2 were further validated in the developing P0 mouse retina. In addition, we confirmed that the inactivation of JNK1 K55N mutant significantly reduced the JNK1-mediated phosphorylation of OTX2 by performing an immune complex protein kinase assay.

CONCLUSION

c-Jun N-terminal kinase 1 (JNK1) phosphorylates OTX2 transcription factor through the protein-protein interaction.

Mercury Chloride but Not Lead Acetate Causes Apoptotic Cell Death in Human Lung Fibroblast MRC5 Cells via Regulation of Cell Cycle Progression

Heavy metals are important for various biological systems, but, in excess, they pose a serious risk to human health. Heavy metals are commonly used in consumer and industrial products. Despite the increasing evidence on the adverse effects of heavy metals, the detailed mechanisms underlying their action on lung cancer progression are still poorly understood. In the present study, we investigated whether heavy metals (mercury chloride and lead acetate) affect cell viability, cell cycle, and apoptotic cell death in human lung fibroblast MRC5 cells. The results showed that mercury chloride arrested the sub-G₁ and G₂/M phases by inducing cyclin B1 expression. In addition, the exposure to mercury chloride increased apoptosis through the activation of caspase-3. However, lead had no cytotoxic effects on human lung fibroblast MRC5 cells at low concentration. These findings demonstrated that mercury chloride affects the cytotoxicity of MRC5 cells by increasing cell cycle progression and apoptotic cell death.

Transcriptome Analysis Reveals HgCl2 Induces Apoptotic Cell Death in Human Lung Carcinoma H1299 Cells through Caspase-3-Independent Pathway

Mercury is one of the detrimental toxicants that can be found in the environment and exists naturally in different forms; inorganic and organic. Human exposure to inorganic mercury, such as mercury chloride, occurs through air pollution, absorption of food or water, and personal care products. This study aimed to investigate the effect of HgCl₂ on cell viability, cell cycle, apoptotic pathway, and alters of the transcriptome profiles in human non-small cell lung cancer cells, H1299. Our data show that HgCl₂ treatment causes inhibition of cell growth via cell cycle arrest at G₀/G₁- and S-phase. In addition, HgCl₂ induces apoptotic cell death through the caspase-3-independent pathway. Comprehensive transcriptome analysis using RNA-seq indicated that cellular nitrogen compound metabolic process, cellular metabolism, and translation for biological processes-related gene sets were significantly up- and downregulated by HgCl₂ treatment. Interestingly, comparative gene expression patterns by RNA-seq indicated that mitochondrial ribosomal proteins were markedly altered by low-dose of HgCl₂ treatment. Altogether, these data show that HgCl₂ induces apoptotic cell death through the dysfunction of mitochondria.

Ethylparaben induces apoptotic cell death in human placenta BeWo cells via the Caspase-3 pathway

Parabens are generally used as preservatives in foods, pharmaceuticals, and various other commercial products. Among them, ethylparaben has weaker estrogenic characteristics than endogenous estrogen. However, growing evidence indicates that ethylparaben has an adverse effect on various human tissues. Here, we investigated whether ethylparaben induces cell death by affecting cell viability, cell proliferation, cell cycle, and apoptosis using the human placenta cell line BeWo. Ethylparaben significantly decreased cell viability in a dose-dependent manner. It caused cell cycle arrest at sub-G1 by reducing the expression of cyclin D1, whereas it decreased the cell proportion at the G0/G1 and S phases. Furthermore, we verified that ethylparaben induces apoptotic cell death by enhancing the activity of Caspase-3. Taken together, our results suggest that ethylparaben exerts cytotoxic effects in human placental BeWo cells via cell cycle arrest and apoptotic pathways.

Transcriptome dynamics of alternative splicing events revealed early phase of apoptosis induced by methylparaben in H1299 human lung carcinoma cells

Methylparaben is most frequently used as an antimicrobial preservative in pharmaceuticals and foods. Methylparaben has been subjected to toxicological studies owing to the increasing concern regarding its possible impact on the environment and human health. However, the cytotoxicity and underlying mechanisms of methylparaben exposure in human lung cells have not been explored. Here, we investigated the effect of methylparaben on cell cycle, apoptotic pathways, and changes in the transcriptome profiles in human lung cells. Our results demonstrate that treatment with methylparaben causes inhibition of cell growth. In addition, methylparaben induced S- and G2/M-phase arrest as a result of enhanced apoptosis. Transcriptome analysis using RNA-seq revealed that mRNA expression of ER stress- and protein misfolding-related gene sets was upregulated in methylparaben-treated group. RNA splicing- and maturation-related gene sets were significantly down-regulated by methylparaben treatment. Interestingly, RNA-seq analysis at the transcript level revealed that alternative splicing events, especially retained intron, were markedly changed by a low dose of methylparaben treatment. Altogether, these data show that methylparaben induces an early phase of apoptosis through cell cycle arrest and downregulation of mRNA maturation.

[Research on knowledge status and relevant factors of breastfeeding among medical staff in China based on network platform]

From August 1(st) to 7(th), 2017, the breastfeeding knowledge of medical staff were collected from 52 medical health institutions in 29 provinces through a network system. A total of 35 243 questionnaires were included in the study to analyze the current status of breastfeeding knowledge and related factors. The qualified rate of breastfeeding knowledge questionnaires for medical staff in this study was 75.3% (26 546/35 243). Compared with those in the eastern region and those who were mothers, the qualified rate of breastfeeding knowledge of medical staff in the central region or the western region and medical staff who were fathers or expectant parents was lower, with OR (95%CI) values about 0.71 (0.67-0.75), 0.66 (0.61-0.72), 0.63 (0.55-0.72) and 0.87 (0.80-0.95), respectively. Compared with those attaining high school education or below and those with children aged<1 month, the qualified rate of breastfeeding knowledge was higher in medical staff with bachelor's degree, graduate degree or above, and with children aged 1-5, 6-23 and ≥24 months, with OR (95%CI) values about 1.92 (1.80-2.05), 2.16 (1.94-2.42), 2.28 (1.93-2.70), 2.41 (2.06-2.83) and 1.99 (1.72-2.32), respectively.

Histone demethylase KDM3B regulates the transcriptional network of cell-cycle genes in hepatocarcinoma HepG2 cells

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third most lethal cancer worldwide. Although gene mutations associated with HCC development have been intensively studied, how epigenetic factors specifically modulate the functional properties of HCC by regulating target gene expression is unclear. Here we demonstrated the overexpression of KDM3B in liver tissue of HCC patients using public RNA-seq data. Ablation of KDM3B by CRISPR/Cas9 retarded the cell cycle and proliferation of hepatocarcinoma HepG2 cells. Approximately 30% of KDM3B knockout cells exhibited mitotic spindle multipolarity as a chromosome instability (CIN) phenotype. RNA-seq analysis of KDM3B knockout revealed significantly down-regulated expression of cell cycle related genes, especially cell proliferation factor CDC123. Furthermore, the expression level of Cyclin D1 was reduced in KDM3B knockout by proteosomal degradation without any change in the expression of CCND1, which encodes Cyclin D1. The results implicate KDM3B as a crucial epigenetic factor in cell cycle regulation that manipulates chromatin dynamics and transcription in HCC, and identifies a potential gene therapy target for effective treatment of HCC.

Transcriptome analysis for UVB-induced phototoxicity in mouse retina

Throughout life, the human eye is continuously exposed to sunlight and artificial lighting. Ambient light exposure can lead to visual impairment and transient or permanent blindness. To mimic benign light stress conditions, Mus musculus eyes were exposed to low-energy UVB radiation, ensuring no severe morphological changes in the retinal structure post-exposure. We performed RNA-seq analysis to reveal the early transcriptional changes and key molecular pathways involved before the activation of the canonical cell death pathway. RNA-seq analysis identified 537 genes that were differentially modulated, out of which 126 were clearly up regulated (>2-fold, P < .01) and 51 were significantly down regulated (<2-fold, P < .01) in response to UVB irradiation in the mouse retina. Gene ontology analysis revealed that UVB exposure affected pathways for cellular stress and signaling (eg, Creb3, Ddrgk1, Grin1, Map7, Uqcc2, Uqcrb), regulation of chromatin and gene expression (eg, Chd5, Jarid2, Kat6a, Smarcc2, Sumo1, Zfp84), transcription factors (eg, Asxl2, Atf7, Per1, Phox2a, Rxra), RNA processing, and neuronal genes (eg, B4gal2, Drd1, Grm5, Rnf40, Rnps1, Usp39, Wbp4). The differentially expressed genes from the RNA-seq analysis were validated by quantitative PCR. Both analyses yielded similar gene expression patterns. The genes and pathways identified here improve the understanding of early transcriptional responses to UVB irradiation. They may also help in elucidating the genes responsible for the inherent susceptibility of humans to UVB-induced retinal diseases.

Histone deacetylase 1 (HDAC1) regulates retinal development through a PAX6-dependent pathway

Cell fate determination is tightly controlled by the expression of transcription factors and gene regulatory networks. PAX6 is a transcription factor containing a DNA-binding paired-box domain and homeobox domain that plays a key role in the development of the eye, brain, and pancreas. Here, we showed that histone deacetyltransferase 1 (HDAC1) is a novel binding partner of PAX6 in newborn mouse retinas. We also showed that HDAC1 specifically binds to the paired and transactivation domains of PAX6, and these physical interactions were required for effective repression of PAX6 transcriptional activity during retinal development. Furthermore, HDAC1 preferentially regulates the transcriptional activity of PAX6 when it binds to paired-domain (P6CON and chimeric pCON/P3) PAX6 responsive elements compared to homeodomain (pP3) PAX6 responsive elements. The repressive effect of HDAC1 on the transcriptional activity of PAX6 was reversed by knockdown of HDAC1 or treatment with an HDAC inhibitor, TSA. Taken together, these results show that HDAC1 binds PAX6 and that protein-protein interaction leads to transcriptional repression of PAX6 target genes during mouse retinal development.