NR0B1 suppresses ferroptosis through upregulation of NRF2/c-JUN-CBS signaling pathway in lung cancer cells

Ferroptosis has demonstrated significant potential in treating radiochemotherapy-resistant cancers, but its efficacy can be affected by recently discovered ferroptosis suppressors. In this study, we discovered that NR0B1 protects against erastin- or RSL3-induced ferroptosis in lung cancer cells. Transcriptomic analysis revealed that NR0B1 significantly interfered with the expression of 12 ferroptosis-related genes, and the expression level of NR0B1 positively correlated with that of c-JUN, NRF2, and CBS. We further revealed that NR0B1 suppression of ferroptosis depended on the activities of c-JUN, NRF2, and CBS. NR0B1 directly promoted the expression of NRF2 and c-JUN and indirectly upregulated CBS expression through enhancing NRF2 and/or c-JUN transcription. Moreover, we showed that NR0B1 depletion restrained xenograft tumor growth and facilitated RSL3-induced ferroptosis in the tumors. In conclusion, our findings uncover that NR0B1 suppresses ferroptosis by activating the c-JUN/NRF2-CBS signaling pathway in lung cancer cells, providing new evidence for the involvement of NR0B1 in drug resistance during cancer therapy.

CLOCK and BMAL1 stabilize and activate RHOA to promote F-actin formation in cancer cells

Circadian genes control most of the physiological functions in cancer cells, including cell proliferation, migration, and invasion. The CLOCK and BMAL1 complex plays a central role in circadian rhythms. Previous studies have shown that circadian genes may act as oncogenes or tumor-suppressor genes. In addition, F-actin, regulated by RHOA, has been shown to participate in tumor progression. However, the roles of the CLOCK and BMAL1 genes in the regulation of tumor progression via the RHOA-ROCK-CFL pathway remain largely unclear. Here we first indicate that the rearrangement of F-actin is regulated by CLOCK and BMAL1. We found that CLOCK and BMAL1 can upregulate RHOA expression by inhibiting CUL3-mediated ubiquitination and activate RHOA by reducing the interaction between RHOA and RhoGDI. Consequently, CLOCK and BMAL1 control the expression of the components of the RHOA-ROCK-CFL pathway, which alters the dynamics of F-actin/G-actin turnover and promotes cancer cell proliferation, migration, and invasion. In conclusion, our research proposes a novel insight into the role of CLOCK and BMAL1 in tumor cells.

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.

[Identification and functional analysis of a testis-specific E3 ubiquitin ligase gene Rnf148 in mouse]

OBJECTIVE

To investigate the temporal and spatial features of mouse Rnf148 gene expression and the function of RING finger domain of Rnf148 protein.

METHODS

The whole RNA was extracted from different tissues of adult mice, embryo in four developmental stages, and testes of postnatal mice respectively. RT-PCR and Northern blotting analysis were used to investigate the expression of Rnf148 gene in the above tissues. The in vitro expression vector for GST-Rnf148 fused protein was constructed, which encompassing the entire RING domain of Rnf148 protein. GST-Rnf148 fused protein was expressed in Escherichia coli. BL21(DE3) cells and purified with glutathione-sepharose 4B. In vitro ubiquitination assay was performed to analyze whether GST-Rnf148 fused protein possess the function of E3 ubiquitin ligase.

RESULTS

The Mice Rnf148 mRNA expression was only observed in testis, and Northern blotting confirmed that there was only one 1.2 kb mRNA band present in mice testis. Rnf148 mRNA started to appear in the testis of day 21 mice, and then increased dramatically and reached to the highest level in day 25, and continued to express thereafter. GST-Rnf148 fused protein was induced and purified, in vitro ubiquitination reaction showed that the recombinant protein has E3 ubiquitin ligase activity.

CONCLUSION

Rnf148 gene is specifically expressed in mice testis.

Identification of a novel human testicular interstitial gene, RNF148, and its expression regulated by histone deacetylases

Multiple genes are restrictively expressed in mammalian testicular tissues, and they play important roles in the complex process of spermatogenesis. Investigation of these genes and their expression regulation mechanisms is valuable to elucidate the molecular process of spermatogenesis. In this study, we identified a novel human gene, ring finger protein 148 (RNF148) that is abundantly expressed in testes and slightly expressed in pancreas. In situ hybridization analysis showed that RNF148 messenger RNA was mainly present in the interstitial cells of human testicular tissues, and immunohistochemical analysis confirmed protein levels in that location. Treatment with histone deacetylase inhibitor trichostatin A activated the expression of RNF148 messenger RNA in a time- and concentration-dependent manner in HEK293T and HeLa cells, neither of which normally express RNF148. Chromatin immunoprecipitation analysis showed that trichostatin A treatment increased the binding of acetylated histone H3 to the RNF148 gene promoter. We identified a novel human testicular interstitial gene and observed that histone deacetylases regulate RNF148 expression.

[Identification and expression analysis of Macaca mulatta piwil4 gene]

To investigate the structure and expression pattern of rhesus monkey PIWIL4 protein, homologous comparison and reverse transcription PCR (RT-PCR) were carried out to identify rhesus monkey piwil4. The expression of piwil4 mRNA was tested in rhesus monkey heart, brain, colon, epididymis and testis, and the result showed that piwil4 mRNA was expressed in these rhesus monkey tissues. Bioinformatic analysis suggested that the rhesus PIWIL4 protein shared 97% identity in amino acids and the same domains such as PAZ and Piwi with the human PIWIL4 (HIWI2) protein. The immunohistochemical result indicated that PIWIL4 proteins had the same localization in adult testes of the two species, but the distribution of these proteins was altered dynamically at different developmental stages in rhesus monkey testes. PIWIL4 protein was expressed in the nucleus of convoluted seminiferous tubules in infant monkey testes, whereas it was expressed in the cytoplasm of adult monkey testes. The results suggest that piwil4 gene play a similar role in rhesus and human, and different localizations of PIWIL4 protein in infant monkey and adult monkey testes suggest that it functions differently at different developmental stages.

Identification of messenger RNA substrates for mouse T-STAR

Using the method of isolation of specific nucleic acids associated with proteins (SNAAP), we have identified 10 candidate target mRNA substrates bound by mT-STAR (mouse T-STAR protein) from testis extract. Among them, our study focused on Fabp9, a gene that is essential for male gametogenesis, and showed that mT-STAR could directly bind to Fabp9 mRNAs. The binding sites are in a short sequence of the coding region and 3' untranslated region of Fabp9 mRNA. These suggest that mT-STAR can regulate the metabolism and expression of Fabp9. In conclusion, identification of mT-STAR-bound mRNA substrates might help to illustrate the potential spectrum of the process and provide valuable insight into the biological function of this RNA-binding protein in spermatogenesis.

[Construction and expression of eucaryotic recombinant plasmid of Legionella pneumophila mip gene]

OBJECTIVE

To construct recombinant plasmid of Legionella pneumophila mip gene and detect its expression in NIH3T3 cells.

METHODS

mip gene of Legionella pneumophila was amplified by PCR. The amplified DNA was ligated to pcDNA3.1(+) vector. The recombinant plasmid was named pcDNA3.1-mip. NIH3T3 cell was transfected by recombinant plasmid pcDNA3.1-mip with Lipofection strategy. Transient and stable products of mip gene were detected by immunofluorescence and Western-blot.

RESULTS

It was found that there was high green fluorescence on the cell membrane and inside the cell. It showed that NIH3T3 cell was transfected by pcDNA3.1-mip successfully. Rabbit serum antibody of Legionella pneumophila detected the NIH3T3 cell transfected with pcDNA3.1-mip. There was the protein in relative molecular weight 24 X 10(3), whereas no evidence for the protein in NIH3T3 cell transfected with pcDNA3.1(+) was seen. The protein expression of mip gene was shown.

CONCLUSION

We have successfully constructed the recombinant plasmid of Legionella pneumophila mip gene and detected the relative molecular weight 24 X 10(3) Mip protein in NIH3T3 cells.

Co-expression and Immunity of Legionella pneumophila mip Gene and Immunoadjuvant ctxB Gene

The mip gene of Legionella pneumophila and the ctxB gene of Vibrio cholerae were amplified by PCR respectively. The amplified cDNA was ligated to the pcDNA3.1(+) vector. The recombinant plasmids pcDNA3.1-mip and pcDNA3.1-ctxB were identified by restriction analysis and PCR, and further confirmed by sequencing analysis. NIH3T3 cells were transfected with pcDNA3.1-mip and pcDNA3.1-ctxB according to the Lipofection method. Transient and stable products of the co-expression of the mip gene and ctxB gene were detected by immunofluorescence and Western blotting. The results showed that NIH3T3 cells were successfully transfected, and that the transiently and stably co-expressed products can be detected in the transfected cells. To detect the humoral and cellular immune response in immunized mice induced by the coimmunization of the mip and ctxB genes, female BALB/c mice were immunized intramuscularly with pcDNA3.1-mip and pcDNA3.1-ctxB. The results showed that the specific antibody titer and the cytotoxic T-lymphocyte response for pcDNA3.1-mip immunization and co-immunization were increased compared with that of pcDNA3.1(+) immunization. Furthermore, the specific antibody titer and cytotoxic T-lymphocyte response for co-immunization were increased compared with that of pcDNA3.1-mip immunization. Statistical analysis using one-way analysis of variance (ANOVA) showed that there was a significant difference between the groups (P<0.01). The results indicated that the ctxB gene enhanced the humoral and cellular immune response to the mip gene immunization. These findings provide experimental evidence to support the development of the L. pneumophila DNA vaccine.

Co-expression and immunity of Legionella pneumophila mip gene and immunoadjuvant ctxB gene

The mip gene of Legionella pneumophila and the ctxB gene of Vibrio cholerae were amplified by PCR respectively. The amplified cDNA was ligated to the pcDNA3.1(+) vector. The recombinant plasmids pcDNA3.1-mip and pcDNA3.1-ctxB were identified by restriction analysis and PCR, and further confirmed by sequencing analysis. NIH3T3 cells were transfected with pcDNA3.1-mip and pcDNA3.1-ctxB according to the Lipofection method. Transient and stable products of the co-expression of the mip gene and ctxB gene were detected by immunofluorescence and Western blotting. The results showed that NIH3T3 cells were successfully transfected, and that the transiently and stably co-expressed products can be detected in the transfected cells. To detect the humoral and cellular immune response in immunized mice induced by the co-mmunization of the mip and ctxB genes, female BALB/c mice were immunized intramuscularly with pcDNA3.1-mip and pcDNA3.1-ctxB. The results showed that the specific antibody titer and the cytotoxic T-lymphocyte response for pcDNA3.1-mip immunization and co-immunization were increased compared with that of pcDNA3.1(+) immunization. Furthermore, the specific antibody titer and cytotoxic T-lymphocyte response for co-immunization were increased compared with that of pcDNA3.1-mip immunization. Statistical analysis using one-way analysis of variance (ANOVA) showed that there was a significant difference between the groups (P<0.01). The results indicated that the ctxB gene enhanced the humoral and cellular immune response to the mip gene immunization. These findings provide experimental evidence to support the development of the L. pneumophila DNA vaccine.