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Dalton Transactions (Cambridge, England... Jul 2024Currently, there are many uses of metal complexes, especially in the fields of medicinal chemistry and catalysis. Thus, fabrication of new complexes which perform as a...
Fabrication of thiosemicarbazone-based Pd(II) complexes: structural elucidations, catalytic activity towards Suzuki-Miyaura coupling reaction and antitumor activity against TNBC cells.
Currently, there are many uses of metal complexes, especially in the fields of medicinal chemistry and catalysis. Thus, fabrication of new complexes which perform as a catalyst and chemotherapeutic drug is always a beneficial addition to the literature. Herein, we report three heterocyclic thiosemicarbazone-based Pd(II) complexes [Pd(HL1)Cl] (C1), [Pd(L2)(PPh)] (C2) and [Pd(L3)(PPh)]Cl (C3) having coligands Cl and PPh. Thiosemicarbazone ligands (H2L1, H2L2 and HL3) and the complexes (C1-C3) were characterized methodically using several spectroscopic techniques. Single-crystal X-ray diffraction methods reveal that the structural environment around the metal center of C2 is square planar, while for C1 and C3 it is a slighty distorted square plane. The supramolecular network of compounds was built hydrogen bonds, C-H⋯π and π⋯π interactions. Density functional theory (DFT) study of the structure of the complexes supports experimental findings. The application of these complexes as catalysts toward Suzuki-Miyaura coupling reactions has been examined with various aryl halides and phenyl boronic acid in PEG 400 solvent. The complexes displayed good biomolecular interactions with DNA/protein, with a binding constant value of the order of 10 M. C3 showed greater binding efficacy toward these biomolecules than the other complexes, which might be due to the cationic nature of C3. Furthermore, antitumor activity of the complexes was studied against the human triple-negative breast cancer (TNBC) cell line MDA-MB-231. It was found that C3 was more toxic (IC = 10 ± 2.90 μM) toward MDA-MB-231 cells than the other complexes. A known chemotherapeutic drug, 5-fluorouracil, was included as positive control. The programmed cell death mechanism of C3 was confirmed. Additionally, complex-induced apoptosis was confirmed and occurred a mitochondria-dependent (intrinsic) pathway.
PubMed: 38958025
DOI: 10.1039/d4dt00950a -
Plant & Cell Physiology Jul 2024The INDUCER OF CBF EXPRESSION 1/C-REPEAT BINDING FACTOR (ICE1/CBF) pathway plays a crucial role in plant responses to cold stress, impacting growth and development....
The INDUCER OF CBF EXPRESSION 1/C-REPEAT BINDING FACTOR (ICE1/CBF) pathway plays a crucial role in plant responses to cold stress, impacting growth and development. Here, we demonstrated that ATBS1-INTERACTING FACTOR 2 (AIF2), a non-DNA-binding basic helix-loop-helix transcription factor, positively regulates freezing tolerance through the ICE1/CBF-induced cold tolerance pathway in Arabidopsis. Cold stress transcriptionally upregulated AIF2 expression and induced AIF2 phosphorylation, thereby stabilizing the AIF2 protein during early stages of cold acclimation. The AIF2 loss-of-function mutant, aif2-1, exhibited heightened sensitivity to freezing before and after cold acclimation. In contrast, ectopic expression of AIF2, but not the C-terminal-deleted AIF2 variant, restored freezing tolerance. AIF2 enhanced ICE1 stability during cold acclimation and promoted the transcriptional expression of CBFs and downstream cold-responsive genes, ultimately enhancing plant tolerance to freezing stress. MITOGEN-ACTIVATED PROTEIN KINASES 3 and 6 (MPK3/6), known negative regulators of freezing tolerance, interacted with and phosphorylated AIF2, subjecting it to protein degradation. Furthermore, transient co-expression of MPK3/6 with AIF2 and ICE1 downregulated AIF2/ICE1-induced transactivation of CBF2 expression. AIF2 interacted preferentially with BIN2 and MPK3/6 during the early and later stages of cold acclimation, respectively, thereby differentially regulating AIF2 activity in a cold acclimation time-dependent manner. Moreover, AIF2 acted additively in a gain-of-function mutant of BRASSINAZOLE-RESISTANT 1 (BZR1; bzr1-1D) and a triple knockout mutant of BRASSINOSTEROID-INSENSITIVE 2 (BIN2) and its homologs (bin2bil1bil2) to induce CBFs-mediated freezing tolerance. This suggests that cold-induced AIF2 coordinates freezing tolerance along with BZR1 and BIN2, key positive and negative components, respectively, of brassinosteroid signaling pathways.
PubMed: 38957969
DOI: 10.1093/pcp/pcae072 -
Journal of Cancer Prevention Jun 2024The identification of therapeutic target genes that are functionally involved in stemness is crucial to effectively cure patients with metastatic carcinoma. We have...
The identification of therapeutic target genes that are functionally involved in stemness is crucial to effectively cure patients with metastatic carcinoma. We have previously reported that inhibition of ribosomal protein L9 (RPL9) expression suppresses the growth of colorectal cancer (CRC) cells by inactivating the inhibitor of DNA-binding 1 (ID-1) signaling axis, which is functionally associated with cancer cell survival. In addition to cell proliferation, ID-1 is also involved in the maintenance of cancer stemness. Thus, we aimed in this study to investigate whether the function of RPL9 could correlate with CRC stem cell-like properties. Here, we demonstrated that siRNA silencing of RPL9 reduced the invasiveness and migrative capabilities of HT29 and HCT116 parental cell populations and the capacity for sphere formation in the HT29 parental cell population. CD133 cancer stem cells (CSCs) were then separated from CD133 cancer cells of the HT29 parental cell culture and treated with RPL9-specific siRNAs to verify the effects of RPL9 targeting on stemness. As a result, knockdown of RPL9 significantly suppressed the proliferative potential of CD133 colorectal CSCs, accompanied by a reduction in CD133, ID-1, and p-IκBα levels. In line with these molecular alterations, targeting RPL9 inhibited the invasion, migration, and sphere-forming capacity of CD133 HT29 CSCs. Taken together, these findings suggest that RPL9 promotes CRC stemness via ID-1 and that RPL9 could be a potential therapeutic target for both primary CRC treatment and the prevention of metastasis and/or recurrence.
PubMed: 38957590
DOI: 10.15430/JCP.24.004 -
Environmental Microbiome Jul 2024Microbial methane oxidation, methanotrophy, plays a crucial role in mitigating the release of the potent greenhouse gas methane from aquatic systems. While aerobic...
BACKGROUND
Microbial methane oxidation, methanotrophy, plays a crucial role in mitigating the release of the potent greenhouse gas methane from aquatic systems. While aerobic methanotrophy is a well-established process in oxygen-rich environments, emerging evidence suggests their activity in hypoxic conditions. However, the adaptability of these methanotrophs to such environments has remained poorly understood. Here, we explored the genetic adaptability of aerobic methanotrophs to hypoxia in the methanogenic sediments of Lake Kinneret (LK). These LK methanogenic sediments, situated below the oxidic and sulfidic zones, were previously characterized by methane oxidation coupled with iron reduction via the involvement of aerobic methanotrophs.
RESULTS
In order to explore the adaptation of the methanotrophs to hypoxia, we conducted two experiments using LK sediments as inoculum: (i) an aerobic "classical" methanotrophic enrichment with ambient air employing DNA stable isotope probing (DNA-SIP) and (ii) hypoxic methanotrophic enrichment with repeated spiking of 1% oxygen. Analysis of 16S rRNA gene amplicons revealed the enrichment of Methylococcales methanotrophs, being up to a third of the enriched community. Methylobacter, Methylogaea, and Methylomonas were prominent in the aerobic experiment, while hypoxic conditions enriched primarily Methylomonas. Using metagenomics sequencing of DNA extracted from these experiments, we curated five Methylococcales metagenome-assembled genomes (MAGs) and evaluated the genetic basis for their survival in hypoxic environments. A comparative analysis with an additional 62 Methylococcales genomes from various environments highlighted several core genetic adaptations to hypoxia found in most examined Methylococcales genomes, including high-affinity cytochrome oxidases, oxygen-binding proteins, fermentation-based methane oxidation, motility, and glycogen use. We also found that some Methylococcales, including LK Methylococcales, may denitrify, while metals and humic substances may also serve as electron acceptors alternative to oxygen. Outer membrane multi-heme cytochromes and riboflavin were identified as potential mediators for the utilization of metals and humic material. These diverse mechanisms suggest the ability of methanotrophs to thrive in ecological niches previously thought inhospitable for their growth.
CONCLUSIONS
Our study sheds light on the ability of enriched Methylococcales methanotrophs from methanogenic LK sediments to survive under hypoxia. Genomic analysis revealed a spectrum of genetic capabilities, potentially enabling these methanotrophs to function. The identified mechanisms, such as those enabling the use of alternative electron acceptors, expand our understanding of methanotroph resilience in diverse ecological settings. These findings contribute to the broader knowledge of microbial methane oxidation and have implications for understanding and potential contribution methanotrophs may have in mitigating methane emissions in various environmental conditions.
PubMed: 38956741
DOI: 10.1186/s40793-024-00586-1 -
Scientific Reports Jul 2024Environmental temperature strongly influences the adaptation dynamics of amphibians, whose limited regulation capabilities render them susceptible to thermal...
Environmental temperature strongly influences the adaptation dynamics of amphibians, whose limited regulation capabilities render them susceptible to thermal oscillations. A central element of the adaptive strategies is the transcription factors (TFs), which act as master regulators that orchestrate stress responses, enabling species to navigate the fluctuations of their environment skillfully. Our study delves into the intricate relationship between TF expression and thermal adaptation mechanisms in the Rhinella spinulosa populations. We sought to elucidate the dynamic modulations of TF expression in prometamorphic and metamorphic tadpoles that inhabit two thermally contrasting environments (Catarpe and El Tatio Geyser, Chile) and which were exposed to two thermal treatments (25 °C vs. 20 °C). Our findings unravel an intriguing dichotomy in response strategies between these populations. First, results evidence the expression of 1374 transcription factors. Regarding the temperature shift, the Catarpe tadpoles show a multifaceted approach by up-regulating crucial TFs, including fosB, atf7, and the androgen receptor. These dynamic regulatory responses likely underpin the population's ability to navigate thermal fluctuations effectively. In stark contrast, the El Tatio tadpoles exhibit a more targeted response, primarily up-regulating foxc1. This differential expression suggests a distinct focus on specific TFs to mitigate the effects of temperature variations. Our study contributes to understanding the molecular mechanisms governing thermal adaptation responses and highlights the resilience and adaptability of amphibians in the face of ever-changing environmental conditions.
Topics: Animals; Transcription Factors; Temperature; Larva; Adaptation, Physiological; Bufonidae; Anura; Acclimatization; Chile
PubMed: 38956427
DOI: 10.1038/s41598-024-66127-5 -
Scientific Reports Jul 2024Targeting intracellular inhibiting proteins has been revealed to be a promising strategy to improve CD8 T cell anti-tumor efficacy. Here, we are focusing on...
Targeting intracellular inhibiting proteins has been revealed to be a promising strategy to improve CD8 T cell anti-tumor efficacy. Here, we are focusing on intracellular inhibiting proteins specific to TCR signaling: DOK1 and DOK2 expressed in T cells. We hypothesized that depletion of intracellular inhibition checkpoint DOK1 and DOK2 could improve CD8 T-cell based cancer therapies. To evaluate the role of DOK1 and DOK2 depletion in physiology and effector function of CD8 T lymphocytes and in cancer progression, we established a transgenic T cell receptor mouse model specific to melanoma antigen hgp100 (pmel-1 TCR Tg) in WT and Dok1/Dok2 DKO (double KO) mice. We showed that both DOK1 and DOK2 depletion in CD8 T cells after an in vitro pre-stimulation induced a higher percentage of effector memory T cells as well as an up regulation of TCR signaling cascade- induced by CD3 mAbs, including the increased levels of pAKT and pERK, two major phosphoproteins involved in T cell functions. Interestingly, this improved TCR signaling was not observed in naïve CD8 T cells. Despite this enhanced TCR signaling essentially shown upon stimulation via CD3 mAbs, pre-stimulated Dok1/Dok2 DKO CD8 T cells did not show any increase in their activation or cytotoxic capacities against melanoma cell line expressing hgp100 in vitro. Altogether we demonstrate here a novel aspect of the negative regulation by DOK1 and DOK2 proteins in CD8 T cells. Indeed, our results allow us to conclude that DOK1 and DOK2 have an inhibitory role following long term T cell stimulations.
Topics: Animals; CD8-Positive T-Lymphocytes; RNA-Binding Proteins; Signal Transduction; Mice; Adaptor Proteins, Signal Transducing; Phosphoproteins; DNA-Binding Proteins; Immunologic Memory; Receptors, Antigen, T-Cell; Mice, Knockout; Cell Line, Tumor; Mice, Transgenic
PubMed: 38956389
DOI: 10.1038/s41598-024-66075-0 -
Nature Structural & Molecular Biology Jul 2024The canonical BRG/BRM-associated factor (cBAF) complex is essential for chromatin opening at enhancers in mammalian cells. However, the nature of the open chromatin...
The canonical BRG/BRM-associated factor (cBAF) complex is essential for chromatin opening at enhancers in mammalian cells. However, the nature of the open chromatin remains unclear. Here, we show that, in addition to producing histone-free DNA, cBAF generates stable hemisome-like subnucleosomal particles containing the four core histones associated with 50-80 bp of DNA. Our genome-wide analysis indicates that cBAF makes these particles by targeting and splitting fragile nucleosomes. In mouse embryonic stem cells, these subnucleosomes become an in vivo binding substrate for the master transcription factor OCT4 independently of the presence of OCT4 DNA motifs. At enhancers, the OCT4-subnucleosome interaction increases OCT4 occupancy and amplifies the genomic interval bound by OCT4 by up to one order of magnitude compared to the region occupied on histone-free DNA. We propose that cBAF-dependent subnucleosomes orchestrate a molecular mechanism that projects OCT4 function in chromatin opening beyond its DNA motifs.
PubMed: 38956169
DOI: 10.1038/s41594-024-01344-0 -
Nature Neuroscience Jul 2024Direct neuronal reprogramming is a promising approach to regenerate neurons from local glial cells. However, mechanisms of epigenome remodeling and co-factors...
Direct neuronal reprogramming is a promising approach to regenerate neurons from local glial cells. However, mechanisms of epigenome remodeling and co-factors facilitating this process are unclear. In this study, we combined single-cell multiomics with genome-wide profiling of three-dimensional nuclear architecture and DNA methylation in mouse astrocyte-to-neuron reprogramming mediated by Neurogenin2 (Ngn2) and its phosphorylation-resistant form (PmutNgn2), respectively. We show that Ngn2 drives multilayered chromatin remodeling at dynamic enhancer-gene interaction sites. PmutNgn2 leads to higher reprogramming efficiency and enhances epigenetic remodeling associated with neuronal maturation. However, the differences in binding sites or downstream gene activation cannot fully explain this effect. Instead, we identified Yy1, a transcriptional co-factor recruited by direct interaction with Ngn2 to its target sites. Upon deletion of Yy1, activation of neuronal enhancers, genes and ultimately reprogramming are impaired without affecting Ngn2 binding. Thus, our work highlights the key role of interactors of proneural factors in direct neuronal reprogramming.
PubMed: 38956165
DOI: 10.1038/s41593-024-01677-5 -
Nature Communications Jul 2024Diatoms often outnumber other eukaryotic algae in the oceans, especially in coastal environments characterized by frequent fluctuations in light intensity. The...
Diatoms often outnumber other eukaryotic algae in the oceans, especially in coastal environments characterized by frequent fluctuations in light intensity. The identities and operational mechanisms of regulatory factors governing diatom acclimation to high light stress remain largely elusive. Here, we identified the AUREO1c protein from the coastal diatom Phaeodactylum tricornutum as a crucial regulator of non-photochemical quenching (NPQ), a photoprotective mechanism that dissipates excess energy as heat. AUREO1c detects light stress using a light-oxygen-voltage (LOV) domain and directly activates the expression of target genes, including LI818 genes that encode NPQ effector proteins, via its bZIP DNA-binding domain. In comparison to a kinase-mediated pathway reported in the freshwater green alga Chlamydomonas reinhardtii, the AUREO1c pathway exhibits a faster response and enables accumulation of LI818 transcript and protein levels to comparable degrees between continuous high-light and fluctuating-light treatments. We propose that the AUREO1c-LI818 pathway contributes to the resilience of diatoms under dynamic light conditions.
Topics: Diatoms; Light; Acclimatization; Chlamydomonas reinhardtii; Algal Proteins; Gene Expression Regulation
PubMed: 38956103
DOI: 10.1038/s41467-024-49991-7 -
Bioconjugate Chemistry Jul 2024The chemical synthesis of homogeneously ubiquitylated histones is a powerful approach to decipher histone ubiquitylation-dependent epigenetic regulation. Among the...
The chemical synthesis of homogeneously ubiquitylated histones is a powerful approach to decipher histone ubiquitylation-dependent epigenetic regulation. Among the various methods, α-halogen ketone-mediated conjugation chemistry has recently been an attractive strategy to generate single-monoubiquitylated histones for biochemical and structural studies. Herein, we report the use of this strategy to prepare not only dual- and even triple-monoubiquitylated histones but also diubiquitin-modified histones. We were surprised to find that the synthetic efficiencies of multi-monoubiquitylated histones were comparable to those of single-monoubiquitylated ones, suggesting that this strategy is highly tolerant to the number of ubiquitin monomers installed onto histones. The facile generation of a series of single-, dual-, and triple-monoubiquitylated H3 proteins enabled us to evaluate the influence of ubiquitylation patterns on the binding of DNA methyltransferase 1 (DNMT1) to nucleosomes. Our study highlights the potential of site-specific conjugation chemistry to generate chemically defined histones for epigenetic studies.
PubMed: 38954775
DOI: 10.1021/acs.bioconjchem.4c00130