Regulation of the Histone Deacetylase Hst3 by Cyclin-dependent Kinases and the Ubiquitin Ligase SCFCdc4

In Saccharomyces cerevisiae, histone H3 lysine 56 acetylation (H3K56ac) is a modification of new H3 molecules deposited throughout the genome during S-phase. H3K56ac is removed by the sirtuins Hst3 and Hst4 at later stages of the cell cycle. Previous studies indicated that regulated degradation of Hst3 plays an important role in the genome-wide waves of H3K56 acetylation and deacetylation that occur during each cell cycle. However, little is known regarding the mechanism of cell cycle-regulated Hst3 degradation. Here, we demonstrate that Hst3 instability in vivo is dependent upon the ubiquitin ligase SCF^Cdc4 and that Hst3 is phosphorylated at two Cdk1 sites, threonine 380 and threonine 384. This creates a diphosphorylated degron that is necessary for Hst3 polyubiquitylation by SCF^Cdc4. Mutation of the Hst3 diphospho-degron does not completely stabilize Hst3 in vivo, but it nonetheless results in a significant fitness defect that is particularly severe in mutant cells treated with the alkylating agent methyl methanesulfonate. Unexpectedly, we show that Hst3 can be degraded between G₂ and anaphase, a window of the cell cycle where Hst3 normally mediates genome-wide deacetylation of H3K56. Our results suggest an intricate coordination between Hst3 synthesis, genome-wide H3K56 deacetylation by Hst3, and cell cycle-regulated degradation of Hst3 by cyclin-dependent kinases and SCF^Cdc4.     

Predicting efficiency of different chemical extraction methods in risk assessment of trace metals in sediment of the Persian Gulf

Different chemical methods have been developed to evaluate the bioavailable fraction of the trace metals. Due to the lack of a universal method for analysis of the bioavailable metal fractions, due to the differences in sediment characteristics, it is necessary to validate an appropriate chemical method for assessing the available fraction of trace metals. For this propose, in this study, different chemical extraction methods including extraction with HCl and desorption test as a single reagent leaching test as well as geochemical fractions method have been evaluated. Bushehr coastal sediments in the Persian Gulf coasts have been selected for this purpose. To validate the efficacy of these methods, a gastropod species (Trochus erithreus), as a bioindicator, has been selected and monitored for trace metals of Fe²⁺, Pb²⁺, Cu²⁺, Zn²⁺, Mn²⁺, and Ni²⁺. According to the one-way ANOVA results, all partial extraction methods for all the trace metals (except for Mn²⁺) showed no significant variation, but linear correlation coefficients were between the results of the selective chemical extraction methods and concentrations of trace metals in organism tissues. It offered that selective extraction with HCl can be used as a simple method for measuring the bioavailable fraction of the metals in the sediments.     

Dose-dependent therapeutic effects of topical 1,25 OH-vitamin D3 on corneal wound healing

Molecular Biology Reports - Conflicting results have been reported regarding the effects of 1,25 OH-vitamin D3 on corneal wound healing. Therefore, we undertook this study to determine whether the...     

Development of an anti-CD45RA-quantum dots conjugated scFv to detect leukemic cancer stem cells

Molecular Biology Reports - Leukemic cancer stem cells (LSCs), aberrantly overexpressing CD45RA are among the major causes of relapse following chemotherapy in patients with acute myeloid leukemia...     

Central Opioidergic and Adrenergic systems Mediates Food Intake via α1, α2 and β2 Receptors in Neonatal Layer-Type Chicken

International Journal of Peptide Research and Therapeutics - The aim of the current study was to determine possible interaction of central Opioidergic and Adrenergic systems on food intake...