Dynamic Activity of Histone H3-Specific Chaperone Complexes in Oncogenesis

Canonical histone H3.1 and variant H3.3 deposit at different sites of the chromatin via distinct histone chaperones. Histone H3.1 relies on chaperone CAF-1 to mediate replication-dependent nucleosome assembly during S-phase, while H3.3 variant is regulated and incorporated into the chromatin in a replication-independent manner through HIRA and DAXX/ATRX. Current literature suggests that dysregulated expression of histone chaperones may be implicated in tumor progression. Notably, ectopic expression of CAF-1 can promote a switch between canonical H3.1 and H3 variants in the chromatin, impair the chromatic state, lead to chromosome instability, and impact gene transcription, potentially contributing to carcinogenesis. This review focuses on the chaperone proteins of H3.1 and H3.3, including structure, regulation, as well as their oncogenic and tumor suppressive functions in tumorigenesis.

DIRECTIONS OF STATE SUPPORT DIGITALIZATION OF AGRICULTURE OF RUSSIA

State support for the development of agriculture, like other subsidized industries, has a significant impact on the development of crop and livestock products, acting as a strategic bulwark of the country's food security. An increase in the volume of state support for agriculture is possible with the dynamic activity of all sectors of agriculture, the main task of which is to increase economic efficiency through the transition to innovative production principles. State support for the technical re-equipment of agribusiness is the basis of agricultural production, which has a decisive impact on the transition to digital solutions for the entire agrarian industry in the future. In this regard, the goal was set to analyze the effectiveness of the implementation of digital technologies using the example of typical agricultural enterprises of the Republic of Tatarstan located in different climatic zones of the Volga region, confirming an average decrease in the production cost of 1 centner of grain crops by 13%, payment labor on average by 14.5%, which makes it necessary to allocate financial support to agrarians as an effective mechanism for increasing the efficiency of agribusiness based on funds from the federal and regional budgets of the constituent entities of the Russian Federation and from extra-budgetary sources. Revealing the mechanism of state regulation in the form of tax, control and inspection, as well as the mechanism of state support and legal regulation, a mechanism of state support for the digitalization process is proposed in the form of subsidizing the costs of purchasing digital products, as one of the effective mechanisms, contributing to the acceleration of the transition of agribusiness to the digital economy. This mechanism will allow agrarians, at the first stage of the digitalization process of agricultural production, to acquire primary digital equipment in the form of trackers and sensors capable of receiving, sending, generating and processing data, which will subsequently lead to the need for the acquisition of interfaces capable of providing unhindered exchange of data between machines and business partners, and later portals in the form of ecosystems

Electrochemical determination of tramadol using modified screen printed electrode

The detection of tramadol using a screen printed electrode modified with La3+/ZnO nano-flowers and multi-walled carbon nanotubes (La3+/ZnO NFs-MWCNTs/SPE) is reported in this work. In order to examine tramadol electrochemical oxidation, the modified electrode was implemented with the utilization of differential pulse voltammetry, chronoamperometry and cyclic voltammetry as diagnostic techniques. The proposed electrode displays favorable electrocatalytic behavior concerning tramadol oxidation with an approximately 330 mV potential shift to a lesser positive potential. In the 0.5 to 800.0 μM range for tramadol, differential pulse voltammetry displays linear dynamic activity. Tramadol detection limit of 0.08 μM was derived within optimized testing conditions for this simple construction sensor. Lastly, this fabricated sensor was utilized with desirable results to determine tramadol in tramadol samples and urine samples.

Motor-independent retraction of type IV pili is governed by an inherent property of the pilus filament

Type IV pili (T4P) are dynamic surface appendages that promote virulence, biofilm formation, horizontal gene transfer, and motility in diverse bacterial species. Pilus dynamic activity is best characterized in T4P that use distinct ATPase motors for pilus extension and retraction. Many T4P systems, however, lack a dedicated retraction motor, and the mechanism underlying this motor-independent retraction remains a mystery. Using the Vibrio cholerae competence pilus as a model system, we identify mutations in the major pilin gene that enhance motor-independent retraction. These mutants likely diminish pilin–pilin interactions within the filament to produce less-stable pili. One mutation adds a bulky residue to α1C, a universally conserved feature of T4P. We found that inserting a bulky residue into α1C of the retraction motor–dependent Acinetobacter baylyi competence T4P enhances motor-independent retraction. Conversely, removing bulky residues from α1C of the retraction motor–independent, V. cholerae toxin-coregulated T4P stabilizes the filament and diminishes pilus retraction. Furthermore, alignment of pilins from the broader type IV filament (T4F) family indicated that retraction motor–independent T4P, gram-positive Com pili, and type II secretion systems generally encode larger residues within α1C oriented toward the pilus core compared to retraction motor–dependent T4P. Together, our data demonstrate that motor-independent retraction relies, in part, on the inherent instability of the pilus filament, which may be a conserved feature of diverse T4Fs. This provides evidence for a long-standing yet previously untested model in which pili retract in the absence of a motor by spontaneous depolymerization.

Spatial regulation of AMPK signaling revealed by a sensitive kinase activity reporter

AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics which coordinates metabolism by phosphorylating a plethora of substrates throughout the cell. But whether AMPK activity is regulated at different subcellular locations to provide precise spatial and temporal control over metabolism is unclear. Genetically encoded AMPK activity reporters (AMPKAR) have provided a window into spatial AMPK activity, but the limited dynamic range of current AMPKARs hinders detailed study. To monitor the dynamic activity of AMPK with high sensitivity, we developed a single-fluorophore AMPK activity reporter (ExRai AMPKAR) that exhibits an excitation ratiometric fluorescence change upon phosphorylation by AMPK, with over 3-fold greater response compared to previous AMPKARs. Using subcellularly localized ExRai AMPKAR, we found that the activity of AMPK at the lysosome and mitochondria are differentially regulated. While different activating conditions, irrespective of their effects on ATP, robustly yet gradually increase mitochondrial AMPK activity, lysosomal AMPK activity accumulates with much faster kinetics. Genetic deletion of the canonical upstream kinase liver kinase B1 (LKB1) resulted in slower AMPK activity at lysosomes but did not affect the response amplitude at either location, in sharp contrast to the necessity of LKB1 for maximal cytoplasmic AMPK activity. We further discovered AMPK activity in the nucleus, which resulted from LKB1-mediated cytoplasmic activation of AMPK followed by nuclear shuttling. Thus, a new, sensitive reporter for AMPK activity, ExRai AMPKAR, in complement with mathematical and biophysical methods, captured subcellular AMPK activity dynamics in living cells and unveiled complex regulation of AMPK signaling within subcellular compartments.

Neuronal activity regulates the nuclear proteome to promote activity-dependent transcription

The formation and plasticity of neuronal circuits relies on dynamic activity-dependent gene expression. Although recent work has revealed the identity of important transcriptional regulators and of genes that are transcribed and translated in response to activity, relatively little is known about the cell biological mechanisms by which activity alters the nuclear proteome of neurons to link neuronal stimulation to transcription. Using nucleus-specific proteomic mapping in silenced and stimulated neurons, we uncovered an understudied mechanism of nuclear proteome regulation: activity-dependent proteasome-mediated degradation. We found that the tumor suppressor protein PDCD4 undergoes rapid stimulus-induced degradation in the nucleus of neurons. We demonstrate that degradation of PDCD4 is required for normal activity-dependent transcription and that PDCD4 target genes include those encoding proteins critical for synapse formation, remodeling, and transmission. Our findings highlight the importance of the nuclear proteasome in regulating the activity-dependent nuclear proteome and point to a specific role for PDCD4 as a regulator of activity-dependent transcription in neurons.

The cerebellum initiates severe tonic-clonic seizures by altering neuronal activity in the ventral posteromedial nucleus (VPM) of the thalamus

Thalamo-cortical networks are central to seizures, yet it's unclear how these circuits initiate the seizures. Here, we test the hypothesis that a facial region of the thalamus, the VPM, is a source of convulsive, tonic-clonic seizures. We devised an in vivo optogenetic mouse model to elicit tonic-clonic seizures by driving convergent input to the VPM. With viral tracing, we show dense cerebellar and cerebral cortical afferent input to the VPM. Lidocaine microinfusions into the cerebellar nuclei selectively block seizure initiation. We perform single-unit electrophysiology recordings during awake, convulsive seizures to define the local activity of thalamic neurons before, during, and after seizure onset. We find highly dynamic activity with biphasic properties, raising the possibility that heterogenous activity patterns promote seizures. These data reveal the VPM as a source of tonic-clonic seizures, with cerebellar input providing the predominant signals.

Adenine Quadruplexes Show Surprising Stability: Potential Implications for SARS-CoV-2

SARS-CoV-2 is an endemic positive-sense RNA virus naturally transmissible between numerous species with notable infectivity and associated mortality. It is characterized by a poly-adenylated structure capping the genomic terminus. This poly(A) tail is crucial to a cascade of viral replicative activity occurring both extra- and intra-cellular during infection. As a route to proposing potential chemotherapy, this study suggests simple biplanar adenine quadruplexes (A4s) which may fold in specific sequences of the viral genome. To the best of our knowledge, uniquely biplanar A4s have not been previously described in any context. Using molecular modeling techniques and molecular dynamics simulations, some of these non-canonical structures show reasonable stability in a biological context. Notably, mRNA configured as a biplanar A4, shows less dynamic activity than DNA equivalents. This observation may be especially relevant in a physiological context. Furthermore, in contrast to well-characterized guanine quadruplexes, co-ordination with cations appears not to impact on stability. Our molecular dynamics simulations and analyses demonstrate that some A4s are stable in biologically relevant terms. These conclusions may apply to SARS-CoV-2, its variants and other pathogenic RNA viruses.