Putative 3-nitrotyrosine detoxifying genes identified in the yeast Debaryomyces hansenii: in silico search of regulatory sequences responsive to salt and nitrogen stress

Background: During salt stress, the yeast Debaryomyces hansenii synthesizes tyrosine as a strategy to avoid the oxidation of proteins. Tyrosine reacts with nitrogen radicals to form 3-nitrotyrosine. 3-nitrotyrosine prevents the effects of associated oxidative stress and thus contributes to the high halotolerace of the yeast. However, the mechanism of how D. hansenii counteracts the presence of this toxic compound is unclear. In this work, we evaluated D. hansenii's capacity to assimilate 3-nitrotyrosine as a unique nitrogen source and measured its denitrase activity under salt stress. To identify putative genes related to the assimilation of 3-nitrotyrosine, we performed an in silico search in the promoter regions of D. hansenii genome. Results: We identified 15 genes whose promoters had binding site sequences for transcriptional factors of sodium, nitrogen, and oxidative stress with oxidoreductase and monooxygenase GO annotations. Two of these genes, DEHA2E24178g and DEHA2C00286g, coding for putative denitrases and having GATA sequences, were evaluated by RT-PCR and showed high expression under salt and nitrogen stress. Conclusions: D. hansenii can grow in the presence of 3-nitrotyrosine as the only nitrogen source and has a high specific denitrase activity to degrade 3-nitrotyrosine in 1 and 2 M NaCl stress conditions. The results suggest that given the lack of information on transcriptional factors in D. hansenii, the genes identified in our in silico analysis may help explain 3-nitrotyrosine assimilation mechanisms.

Biological functions of zinc finger protein ZBTB2: Recent advance / 第二军医大学学报

Zinc finger protein ZBTB20 is a novel member of the ZBTB zinc finger protein family and shares closest homology with BCL-6 and PLZF. Recent studies on genetically modified mice and patient cohort have revealed that ZBTB20 plays indispensable roles in multiple organs and systems, including the nervous system, liver, pancreatic islets, and immune system. ZBTB20 is an essential regulatory factor in a variety of physiological processes, such as ontogenesis, pain sensation, learning and memory, as well as glucose and lipid metabolism. Meanwhile, recent researches have also showed a close relationship between the abnormality or dysfunction of ZBTB20 and pathophysiological procedures of diseases, such as maldevelopment, mental retardation, tumors and metabolic disorders. As a key repressor governing AFP gene transcription, ZBTB20 exerts a great influence on the gene inactivation of liver AFP after birth and is closely related to the prognosis of hepatocellular carcinogenesis. In humans, the deletion of ZBTB20 is detected in diverse tumors and its point mutation leads to Primrose syndrome. This review summarizes the current knowledge concerning the biological functions of ZBTB20.

Genes and oral cancer.

Oral cancers have been one of the leading causes of deaths particularly in the developing countries. Prime reason for this high mortality and morbidity is attributed to the delay in diagnosis and prompt treatment. Relentless research in the field of oncology has led to the advent of novel procedures for the early detection of oral cancers. Molecular biology is highly promising in this regard. It is a procedure that detects alterations at a molecular level much before they are seen under a microscope and much before clinical changes occur. Molecular studies serve as the basis by which we will eventually be able not only to augment clinical assessment and classification of oral lesions but also predict malignant potential of oral lesions, thus reducing the incidence and increasing the scope for early diagnosis and treatment of oral cancers. However, making such sophisticated tools available for the common man in developing countries is one of the most important challenges faced today.