Mice deficient in the nuclear hormone receptor ROR[gamma]t have defective development of thymocytes, lymphoid organs, Th17 cells, and type 3 innate lymphoid cells. ROR[gamma]t binds to oxysterols derived from cholesterol catabolism, but it is not clear whether these are its natural ligands. Here, we show that sterol lipids are necessary and sufficient to drive ROR[gamma]t-dependent transcription. We combined overexpression, RNAi, and genetic deletion of metabolic enzymes to study ROR[gamma]-dependent transcription. Our results are consistent with the ROR[gamma]t ligand(s) being a cholesterol biosynthetic intermediate (CBI) downstream of lanosterol and upstream of zymosterol. Analysis of lipids bound to ROR[gamma] identified molecules with molecular weights consistent with CBIs. Furthermore, CBIs stabilized the ROR[gamma] ligand-binding domain and induced coactivator recruitment. Genetic deletion of metabolic enzymes upstream of the ROR[gamma]t-ligand(s) affected the development of lymph nodes and Th17 cells. Our data suggest that CBIs play a role in lymphocyte development potentially through regulation of ROR[gamma].
COBISS.SI-ID: 3506824
We demonstrate unequivocally that defective cholesterol synthesis is an independent determinant of liver inflammation and fibrosis. We prepared a mouse hepatocyte-specific knockout (LKO) of lanosterol 14 a -demethylase (CYP51) from the part of cholesterol synthesis that is already committed to cholesterol. LKO mice developed hepatomegaly with oval cell proliferation, fibrosis and inflammation, but without steatosis. The key trigger was reduced cholesterol esters that provoked cell cycle arrest, senescence-associated secretory phenotype and ultimately the oval cell response, while elevated CYP51 substrates promoted the integrated stress response. In spite of the oval cell-driven fibrosis being histologically similar in both sexes, data indicates a female-biased down-regulation of primary metabolism pathways and a stronger immune response in males. Liver injury was ameliorated by dietary fats predominantly in females, whereas dietary cholesterol rectified fibrosis in both sexes. Our data place defective cholesterol synthesis as a focus of sex-dependent liver pathologies.
COBISS.SI-ID: 31858137
The bark beetle-associated fungus Grosmannia clavigera participates in the large-scale de-struction of pine forests. In the tree, it must tolerate saturating levels of toxic conifer defense chemicals (e.g. monoterpenes). The fungus can metabolize some of these compounds through the ß-oxidation pathway and use them as a source of carbon. It also uses carbon from pine triglycerides, where oleic acid is the most common fatty acid. High levels of free fatty acids, however, are toxic and can cause additional stress during host colonization. Fatty acids induce expression of neighboring genes encoding a cytochrome P450 (CYP630B18) and its redox partner, cytochrome P450 reductase (CPR2). The aim of this work was to study the function of this novel P450 system. Using LC/MS, we biochemically characterized CYP630 as a highly specific oleic acid omega -hydroxylase. We explain oleic acid specificity using protein interaction modeling. Our results underscore the importance of omega - oxidation when the main ß-oxidation pathway may be overwhelmed by other substrates such as host terpenoid compounds. Because this CYP-CPR gene cluster is evolutionarily conserved, our work has implications for metabolism studies in other fungi.
COBISS.SI-ID: 31899353
This is the first in the series of the three invited review articles, we published in 2015, dealing with heterogeneity and epigenetic changes in cancer. In this paper [A. Videtic Paska, P. Hudler : Aberrant methylation patterns in cancer: a clinical view. Biochemia Medica, ISSN 1330-09622015, vol. 25, no. 2, pp. 161-76] we considered how DNA methylation changes in malignancies, such as breast, pancreatic, colorectal, and gastric cancer could be exploited for the purpose of developing specific diagnostic tools. In the second paper [P. Hudler, A. Videtič Paska, R. Komel: Contemporary proteomic strategies for clinical epigenetic research and potential impact for the clinic. Expert Rew. Proteomics, ISSN 1478-9450, Apr. 2015, vol. 12, No. 2, pp. 197-212] we considered the relationship between epigenetic research in tumorigenesis and the prospect of knowledge transfer to clinical use, focusing primarily on the epigenetic histone post-translational modifications, which could be used as biomarkers. We additionally focused on the use of proteomic techniques in research and evaluated their usefulness in clinical settings. In the third paper [P. Hudler: Challenges of deciphering gastric cancer heterogeneity. World Journal of Gastroenterology, ISSN 1007-9327, Oct. 2015, vol. 21, iss. 37, pp. 10510-10527] we presented details of the molecular heterogeneity of sporadic gastric cancers at the DNA, RNA, and proteome levels and discussed issues relevant to the translation of basic research data to clinically valuable tools. The focus of this work was the identification of relevant molecular changes that could be detected non-invasively.
COBISS.SI-ID: 32016857
This is the first in the series of the three research articles, we published in 2015, dealing with molecular genetic basis of suicide. Since our previous work on completed suicide in Slavic population showed an association of the functional single nucleotide polymorphism (SNP) rs6265 in the brain-derived neurotrophic factor (BDNF) gene, we decided to extend the investigation and test additional SNPs in the BDNF gene, rs7124442, rs10767664, rs962369, rs12273363, rs908867, rs1491850, and rs1491851, for association with completed suicide. In this paper [S. Ropret, T. Zupanc, R. Komel, A. Videtič Paska: Single nucleotide polymorphisms in the BDNF gene and suicide in the Slovenian population. Neurosci. Lett., ISSN 0304-3940, 2015, vol. 602, pp. 12-16] we report that haplotype analysis (rs7124442-rs10767664-rs962369-rs12273363-rs908867) showed an association of the haplotype C-A-T-C-C (pcorr=0.038) with completed suicide, indicating that these SNPs on a haplotype level may play a role in completed suicide phenotype in our study sample. In the second paper [S. Ropret, T. Zupanc, R. Komel, A. Videtič Paska: Data in support of association study of the brain-derived neurotrophic factor gene SNPs and completed suicide in the Slovenian sample. Data in Brief, ISSN 2352-3409, 2015, vol.4, pp. 529-533] we present extended and additional data in support to the findings of the study as shown in the first paper. In the third paper [S. Ropret, T. Zupanc, R. Komel, A. Videtič Paska: Investigating the associations between polymorphisms in the NTRK2 and NGFR genes and completed suicide in the Slovenian sample. Psych. Genet., ISSN 0955-8829, 2015 vol. 6, pp. 241-248] we report the study on the association of 5 NGFR (nerve growth factor receptor) SNPs (rs2072446, rs7219709, rs7224806, rs734194, rs741071, and rs741072) and 6 NTKR2 (neurotrophic tyrosine kinase receptor type 2) SNPs (rs11140714, rs1147198, rs1187323, rs10780691, and rs10868235) with suicide, which is the first study that has examined SNPs in the NTRK2 and NGFR genes for associations with the completed suicide phenotype. Our findings suggested that these SNPs may not be associated particularly with completed suicide in Slovenia, however, they might have a relevant informative value as the study has been carried out on a sample from a population that has one of the highest suicide rates in the world.
COBISS.SI-ID: 32038617