Open Biology最新文献

Retrotransposon Gag-like (RTL) 8A, 8B and 8C are eutherian-specific genes derived from a certain retrovirus. They cluster as a triplet of genes on the X chromosome, but their function remains unknown. Here, we demonstrate that Rtl8a and Rtl8b play important roles in the brain: their double knockout (DKO) mice not only exhibit reduced social responses and increased apathy-like behaviour, but also become obese from young adulthood, similar to patients with late Prader-Willi syndrome (PWS), a neurodevelopmental genomic imprinting disorder. Mouse RTL8A/8B proteins are expressed in the prefrontal cortex and hypothalamus and localize to both the nucleus and cytoplasm of neurons, presumably due to the N-terminal nuclear localization signal-like sequence at the N-terminus. An RNAseq study in the cerebral cortex revealed reduced expression of several GABA type A receptor subunit genes in DKO, in particular Gabrb2, which encodes its β2 subunit. We confirmed the reduction of GABRB2 protein in the DKO cerebral cortex by western blotting. As GABRB2 has been implicated in the aetiology of several neurodevelopmental and neuropsychiatric disorders, it is likely that the reduction of GABRB2 is one of the major causes of the neuropsychiatric defects in the DKO mice.

DNAJC15 is a mitochondrial TIMM23-related co-chaperonin known for its role in regulating oxidative phosphorylation efficiency, oxidative stress response and lipid metabolism. Recently, it has been proposed that the loss of DNAJC15 correlates with cisplatin (CDDP)-resistance onset in ovarian cancer (OC), suggesting this protein as a potential prognostic factor during OC progression. However, the molecular mechanisms through which DNAJC15 contributes to CDDP response remains poorly investigated. Here, we show that high levels of DNAJC15 are associated with accumulation of lipid droplets, decreased tumorigenic features and increased sensitivity to CDDP in OC cells. When overexpressed, DNAJC15 induced a phenotype displaying increased lipid peroxidation and subsequent ferroptosis induction. To prove a role for DNAJC15-induced ferroptosis in promoting sensitivity to CDDP, we reduced lipid peroxidation upon Ferrostatin 1 treatment, which decreased cells' vulnerability to ferroptosis ultimately recovering their CDDP-resistant phenotype. In conclusion, our study uncovers the role of DNAJC15 in modulating ferroptosis activation and in the onset of CDDP resistance in OC cells.

Trace elements are often omitted from chemically defined growth media. From established properties of trace elements, we deduce that this omission makes experiments unnecessarily sensitive to unavoidable contamination with trace elements. We confirm this experimentally by growing 11 bacterial strains in high replicate with and without supplementing trace elements, keeping all other conditions as fixed as possible to isolate the effect of trace elements. We find that supplementing trace elements considerably reduces variability of growth even in this benign scenario, and we argue that typical experimental set-ups exacerbate this. We discuss implications for the design and use of trace-element supplements and in particular argue that their use should be standard practice, as they can reduce variability of almost all experiments using chemically defined media, taking a step towards greater precision and replicability in microbiology.

Abscisic acid (ABA) is a conserved 'stress hormone' in unicellular organisms, plants and animals. In mammals, ABA and its receptors LANCL1 and LANCL2 stimulate insulin-independent cell glucose uptake and oxidative metabolism: overexpression of LANCL1/2 increases, and their silencing conversely reduces, mitochondrial number, respiration and proton gradient dissipation in muscle cells and in brown adipocytes. We hypothesized that the ABA/LANCL hormone/receptors system could be involved in thermogenesis. Heat production by LANCL1/2-overexpressing versus double-silenced cells was compared in rat H9c2 cardiomyocytes with two different methods: differential temperature measurements using sensitive thermistor probes and differential isothermal calorimetry. Overexpressing cells generate an approximately double amount of thermal power compared with double-silenced cells, and addition of ABA further doubles heat production in overexpressing cells. With the temperature probes, we find a timescale of approximately 4 min for thermogenesis to 'turn on' after nutrient addition. We provide direct measurements of increased heat production triggered by the ABA/LANCL hormone receptors system. Combined with previous work on oxphos decoupling, these results support the role of the ABA/LANCL hormone receptors system as a hitherto unknown regulator of cell thermogenesis.

The intricate interplay between viruses and hosts involves microRNAs (miRNAs) to regulate gene expression by targeting cellular/viral messenger RNAs (mRNAs). Mouse mammary tumour virus (MMTV), the aetiological agent of breast cancer and leukaemia/lymphomas in mice, provides an ideal model to explore how viral and host miRNAs interact to modulate virus replication and tumorigenesis. We previously reported dysregulation of host miRNAs in MMTV-infected mammary glands and MMTV-induced tumours, suggesting a direct interaction between MMTV and miRNAs. To explore this further, we systematically examined all potential interactions between host miRNAs and the MMTV genome using advanced prediction tools. Leveraging miRNA sequencing data from MMTV-expressing cells, we identified dysregulated miRNAs capable of targeting MMTV. Docking analysis validated the interaction of three dysregulated miRNAs with the MMTV genome, followed by confirmation with RNA immunoprecipitation assays. We further identified host targets of these miRNAs using mRNA sequencing data from MMTV-expressing cells. These findings should enhance our understanding of how MMTV replicates and interacts with the host to induce cancer in mice, a model important for cancer research. Given MMTV's potential zoonosis and association with human breast cancer/lymphomas, if confirmed, our work could further lead to novel miRNA-based antivirals/therapeutics to prevent possible MMTV transmission and associated cancers in humans.

Protein quantification is an important tool for a wide range of biological applications. The most common methods include the Lowry, bicinchoninic acid (BCA) and Coomassie Bradford assays. Despite their wide applicability, the mechanisms of action imply that these methods may not be ideal for large transmembrane proteins due to the proteins' integration in the plasma membrane. Here, we investigate this problem by assessing the efficacy and applicability of these three common protein quantification methods on a candidate transmembrane protein: Na, K-ATPase (NKA). We compared these methods with an ELISA, which we newly developed and describe here for the quantification of NKA. The use of a relative standard curve allows this ELISA to be easily adapted to other proteins and across the animal kingdom. Our results revealed that the three conventional methods significantly overestimate the concentration of NKA compared with the ELISA. This is due to the samples containing a heterogeneous mix of proteins, including a significant amount of non-target proteins. Further, by applying the protein concentrations determined by the different methods to in vitro assays, we found that variation in the resulting data was consistently low when the assay reactions were prepared based on concentrations determined from the ELISA.

Intensive agricultural practices impact the health and nutrition of pollinators like honey bees (Apis mellifera). Rapeseed (Brassica napus L.) is widely cultivated, providing diverse nutrients and phytochemicals, including S-methyl-L-cysteine sulfoxide (SMCSO). While the nutritional impact of rapeseed on bees is known, SMCSO's effects remain unexplored. We examined SMCSO and its related metabolites-3-methylthiolactic acid sulfoxide and N-acetyl-S-methyl-L-cysteine sulfoxide-analysing their seasonal fluctuations, colony variations and distribution in body parts. Our findings showed that these compounds in bee gut vary among colonies, possibly due to the dietary preferences, and are highly concentrated in bodies during the summer. They are distributed differently within bee bodies, with higher concentrations in the abdomens of foragers compared with nurses. Administration of SMCSO in a laboratory setting showed no immediate toxic effects but significantly boosted bees' antioxidant capacity. Long-term administration decreased bee body weight, particularly in the thorax and head, and altered amino acid metabolism. SMCSO is found in the nectar and pollen of rapeseed flowers and highly accumulates in rapeseed honey compared with other types of honey. This study reveals the dual impact of SMCSO on bee health, providing a basis for further ecological and physiological research to enhance bee health and colony sustainability.

Social deficits play a role in numerous psychiatric, neurological and neurodevelopmental disorders. Relating complex behaviour, such as social interaction, to brain activity remains one of the biggest goals and challenges in neuroscience. Availability of standardized tests that assess social preference is however, limited. Here, we present a novel behavioural paradigm that we developed to measure social behaviour, the modified elevated gap interaction test (MEGIT). In this test, animals are placed on one of two elevated platforms separated by a gap, in which they can engage in whisker interaction with either a conspecific or an object. This allows quantification of social preference in real interaction rather than just proximity and forms an ideal setup for social behaviour-related neuronal recordings. We provide a detailed description of the paradigm and its highly reliable, deep-learning based analysis, and show results obtained from wild-type animals as well as mouse models for disorders characterized by either hyposocial (autism spectrum disorder; ASD) or hypersocial (Williams Beuren syndrome; WBS) behaviour. Wild-type animals show a clear social preference. This preference is significantly smaller in an ASD mouse model, whereas it is larger in WBS mice. The results indicate that MEGIT is a sensitive and reliable test for detecting social phenotypes.

Juvenile hormone (JH) is one of the most essential hormones controlling insect metamorphosis and physiology. While it is well known that JH affects many tissues throughout the insect life cycle, the difference in JH responsiveness and the repertoire of JH-inducible genes among different tissues has not been fully investigated. In this study, we monitored JH responsiveness in vivo using transgenic Drosophila melanogaster flies carrying a JH response element-GFP (JHRE-GFP) construct. Our data highlight the high responsiveness of the epithelial cells within the seminal vesicle, a component of the male reproductive tract, to JH. Specifically, we observe an elevation in the JHRE-GFP signal within the seminal vesicle epithelium upon JH analogue administration, while suppression occurs upon knockdown of a gene encoding the intracellular JH receptor, germ cell-expressed. Starting from published transcriptomic and proteomics datasets, we next identified Lactate dehydrogenase as a JH-response gene expressed in the seminal vesicle epithelium, suggesting insect seminal vesicles undergo metabolic regulation by JH. Together, this study sheds new light on the biology of the insect reproductive regulatory system.

Approximately 10-15% of human cancers are telomerase-negative and maintain their telomeres through a recombination-based process known as the alternative lengthening of telomeres (ALT) pathway. Loss of the alpha-thalassemia/mental retardation, X-linked (ATRX) chromatin remodeller is a common event in ALT-positive cancers, but is generally insufficient to drive ALT induction in isolation. We previously demonstrated that ATRX binds to the MRN complex, which is also known to be important in the ALT pathway, but the molecular basis of this interaction remained elusive. Here, we demonstrate that the interaction between ATRX and MRN is dependent on the N-terminal forkhead-associated and BRCA1 C-terminal domains of NBS1, analogous to the previously reported NBS1-MDC1 interaction. A number of conserved 'SDT-like' motifs (serine and threonine residues with aspartic/glutamic acid residues at proximal positions) in the central unstructured region of ATRX were found to be crucial for the ATRX-MRN interaction. Furthermore, treatment with a casein kinase 2 inhibitor prevented the ability of ATRX to bind MRN, suggesting that phosphorylation of these residues by casein kinase 2 is also important for the interaction. Finally, we show that a functional ATRX-MRN interaction is important for the ability of ATRX to prevent induction of ALT hallmarks in the presence of chemotherapeutically induced DNA-protein crosslinks, and might also have implications for individuals with ATR-X syndrome.