Alternative Mechanisms Research Articles

The microbial metabolite agmatine acts as an FXR agonist to promote polycystic ovary syndrome in female mice.

Polycystic ovary syndrome (PCOS), an endocrine disorder afflicting 6-20% of women of reproductive age globally, has been linked to alterations in the gut microbiome. We previously showed that in PCOS, elevation of Bacteroides vulgatus in the gut microbiome was associated with altered bile acid metabolism. Here we show that B. vulgatus also induces a PCOS-like phenotype in female mice via an alternate mechanism independent of bile acids. We find that B. vulgatus contributes to PCOS-like symptoms through its metabolite agmatine, which is derived from arginine by arginine decarboxylase. Mechanistically, agmatine activates the farnesoid X receptor (FXR) pathway to subsequently inhibit glucagon-like peptide-1 (GLP-1) secretion by L cells, which leads to insulin resistance and ovarian dysfunction. Critically, the GLP-1 receptor agonist liraglutide and the arginine decarboxylase inhibitor difluoromethylarginine ameliorate ovarian dysfunction in a PCOS-like mouse model. These findings reveal that agmatine-FXR-GLP-1 signalling contributes to ovarian dysfunction, presenting a potential therapeutic target for PCOS management.

Nucleolar Localization of the RNA Helicase DDX21 Predicts Survival Outcomes in Gynecological Cancers.

Cancer cells with DNA repair defects (e.g., BRCA1/2 mutant cells) are vulnerable to PARP inhibitors (PARPi) due to induction of synthetic lethality. However, recent clinical evidence has shown that PARPi can prevent the growth of some cancers irrespective of their BRCA1/2 status, suggesting alternative mechanisms of action. We previously discovered one such mechanism in breast cancer involving DDX21, an RNA helicase that localizes to the nucleoli of cells and is a target of PARP1. We have now extended this observation in endometrial and ovarian cancers and provided links to patient outcomes. When PARP1-mediated ADPRylation of DDX21 is inhibited by niraparib, DDX21 is mislocalized to the nucleoplasm resulting in decreased rDNA transcription, which leads to a reduction in ribosome biogenesis, protein translation, and ultimately endometrial and ovarian cancer cell growth. High PARP1 expression was associated with high nucleolar localization of DDX21 in both cancers. High nucleolar DDX21 negatively correlated with calculated IC50s for niraparib. By studying endometrial cancer patient samples, we were able to show that high DDX21 nucleolar localization was significantly associated with decreased survival. Our study suggests that the use of PARP inhibitors as a cancer therapeutic can be expanded to further types of cancers and that DDX21 localization can potentially be used as a prognostic factor and as a biomarker for response to PARPi.

Synthesis and evaluation of antisense oligonucleotides prodrug with G-quadruplex assembly and lysosome escape capabilities for oncotherapy

The applications of antisense oligonucleotides (ASOs) in rare or common diseases treatment have garnered great attention in recent years. Nevertheless, challenges associated with stability and bioavailability still persist, hampering the efficiency of ASOs. This work presents an ASO prodrug with parallel G-quadruplex assembly and lysosome escape capabilities for oncotherapy. Our findings revealed that the end-assembled quadruplex structure effectively shielded the ASO from enzymatic degradation. Meanwhile, the conjugation of maleimide within the quadruplex enhanced cellular uptake, potentially offering an alternative cell entry mechanism that circumvents lysosome involvement. Notably, an optimized molecule, Mal2-G4-ASO, exhibited remarkable therapeutic effects both in vitro and in vivo. This work presents a promising avenue for enhancing the activity of nucleic acid drugs in oncotherapy and potentially other disease contexts.

Lung ILC2s are activated in BALB/c mice born to immunized mothers despite complete protection against respiratory syncytial virus

Activated lung ILC2s produce large quantities of IL-5 and IL-13 that contribute to eosinophilic inflammation and mucus production following respiratory syncytial virus infection (RSV). The current understanding of ILC2 activation during RSV infection, is that ILC2s are activated by alarmins, including IL-33, released from airway epithelial cells in response to viral-mediated damage. Thus, high levels of RSV neutralizing maternal antibody generated from maternal immunization would be expected to reduce IL-33 production and mitigate ILC2 activation. Here we report that lung ILC2s from mice born to RSV-immunized dams become activated despite undetectable RSV replication. We also report, for the first time, expression of activating and inhibitory Fcgamma receptors on ILC2s that are differentially expressed in offspring born to immunized versus unimmunized dams. Alternatively, ex vivo IL-33-mediated activation of ILC2s was mitigated following the addition of antibody: antigen immune complexes. Further studies are needed to confirm the role of Fcgamma receptor ligation by immune complexes as an alternative mechanism of ILC2 regulation in RSV-associated eosinophilic lung inflammation.

Elimination of damaged mitochondria during UVB-induced senescence is orchestrated by NIX-dependent mitophagy.

Skin aging is the result of two types of aging, "intrinsic aging" an inevitable consequence of physiologic and genetically determined changes and "extrinsic aging," which is dependent on external factors such as exposure to sunlight, smoking, and dietary habits. UVB causes skin injury through the generation of free radicals and other oxidative byproducts, also contributing to DNA damage. Appearance and accumulation of senescent cells in the skin are considered one of the hallmarks of aging in this tissue. Mitochondria play an important role for the development of cellular senescence, in particular stress-induced senescence of human cells. However, many aspects of mitochondrial physiology relevant to cellular senescence and extrinsic skin aging remain to be unraveled. Here, we demonstrate that mitochondria damaged by UVB irradiation of human dermal fibroblasts (HDF) are eliminated by NIX-dependent mitophagy and that this process is important for cell survival under these conditions. Additionally, UVB-irradiation of human dermal fibroblasts (HDF) induces the shedding of extracellular vesicles (EVs), and this process is significantly enhanced in UVB-irradiated NIX-depleted cells. Our findings establish NIX as the main mitophagy receptor in the process of UVB-induced senescence and suggest the release of EVs as an alternative mechanism of mitochondrial quality control in HDF.

Understanding Stimulation of Conjugal Gene Transfer by Nonantibiotic Compounds: How Far Are We?

A myriad of nonantibiotic compounds is released into the environment, some of which may contribute to the dissemination of antimicrobial resistance by stimulating conjugation. Here, we analyzed a collection of studies to (i) identify patterns of transfer stimulation across groups and concentrations of chemicals, (ii) evaluate the strength of evidence for the proposed mechanisms behind conjugal stimulation, and (iii) examine the plausibility of alternative mechanisms. We show that stimulatory nonantibiotic compounds act at concentrations from 1/1000 to 1/10 of the minimal inhibitory concentration for the donor strain but that stimulation is always modest (less than 8-fold). The main proposed mechanisms for stimulation via the reactive oxygen species/SOS cascade and/or an increase in cell membrane permeability are not unequivocally supported by the literature. However, we identify the reactive oxygen species/SOS cascade as the most likely mechanism. This remains to be confirmed by firm molecular evidence. Such evidence and more standardized and high-throughput conjugation assays are needed to create technologies and solutions to limit the stimulation of conjugal gene transfer and contribute to mitigating global antibiotic resistance.

Human Umbilical Cord Mesenchymal Stem Cell-derived Exosomes Induce Macrophage M2 Polarization by Antagonizing LPS-mediated Stimulation of the NF-κB and STAT3 Pathways.

Many studies have documented the protective effects of regulating macrophage M1/M2 polarization in inflammatory diseases characterized by their imbalance state. In pathological diseases associated with inflammation, mesenchymal stem cells (MSCs) regulate macrophages, thereby having anti-inflammatory and tissue regenerative effects. Exosomes have been suggested as an alternative mechanism that underlies the paracrine function of MSCs. Thus, this study explored the anti-inflammatory impact of human umbilical cord MSCssecreted exosomes (hucMSCs-EX) by influencing macrophage polarization in normal and inflammatory environments in vitro. In this study, hucMSCs-conditioned medium (hucMSCs-CM) and hucMSCs- EX were used to treat RAW264.7 macrophages with or without LPS. The expressions of TNF- α, IL-10, IL-6, IL-1β, and Arg-1 were quantified by qPCR. The expressions of IL-6 and IL-10 were evaluated by ELISAs. Western blots (WB) were performed to observe the expressions of CD206, NF-κB P65, NF-κB p-p65, p-STAT3, STAT3, and NF-κB phosphorylation. The number of cells expressing CD206 and the fluorescence intensity were measured via flow cytometry (FC) and immunofluorescence staining. Cell propagation and migration were examined via MTT and transwell assays, respectively. The inhibition of LPS-induced inflammatory polarization by hucMSCs-EX or hucMSCs- CM led to increases in IL-10 and arginase (Arg) levels and decreases in those of IL-6 and TNF-α. Moreover, hucMSCs-EX enhanced the CD206 expression in RAW264.7 cells and accelerated the propagation and migration of LPS-induced cells. The suppressive impact of hucMSCs-EX on the LPS-induced phenotypic polarization of M1 macrophages was linked with the reduction of NF-κB signaling. They stimulated the transition of M2 macrophages by enhancing the activity of STAT3 in RAW264.7 cells. This study indicated that hucMSCs-EX enhances the macrophage transition into the M2 phenotype by inhibiting the NF-κB p65 axis and stimulating that of STAT3.

The vascular contribution of apolipoprotein E to Alzheimer's disease.

Alzheimer's disease, the most prevalent form of dementia, imposes a substantial societal burden. The persistent inadequacy of disease-modifying drugs targeting amyloid plaques and neurofibrillary tangles suggests the contribution of alternative pathogenic mechanisms. A frequently overlooked aspect is cerebrovascular dysfunction, which may manifest early in the progression of Alzheimer's disease pathology. Mounting evidence underscores the pivotal role of the apolipoprotein E gene, particularly the apolipoprotein ε4 allele as the strongest genetic risk factor for late-onset AD, in the cerebrovascular pathology associated with Alzheimer's disease. In this review, we examine the evidence elucidating the cerebrovascular impact of both central and peripheral apolipoprotein E on the pathogenesis of Alzheimer's disease. We present a novel three-hit hypothesis, outlining potential mechanisms that shed light on the intricate relationship among different pathogenic events. Finally, we discuss prospective therapeutics targeting the cerebrovascular pathology associated with apolipoprotein E and explore their implications for future research endeavors.

Mental health stigma: a conundrum for healthcare practitioners in conservative communities

This paper presents perspectives on the stigma and shame around mental health in conservative communities, and some of the issues faced by health systems in those communities. The various causes of stigma are explored, and how these are often more pronounced in culturally reserved, conservative communities. While health systems are supposed to provide support for mental health sufferers, this stigma sometimes even extends to healthcare workers, which can discourage patients from asking for assistance. Solutions and reforms are needed, for example education programs; addressing gender norms, and the consideration of culture and religion, to form effective solutions. It is also suggested that alternative therapies and support mechanisms, including digital solutions such as artificial intelligence chatbots, may be useful to provide much needed support to individuals with poor mental health. Along with integrating options such as CBT (cognitive behavioral therapy), it may be useful to draw on indigenous psychologies, such as Islamic psychology, as a way of decolonizing approaches. Therefore, when considering solutions, cultural and religious norms must be considered to ensure their efficacy and acceptance.

CRISPR-Cas13d screens identify KILR, a breast cancer risk-associated lncRNA that regulates DNA replication and repair

BackgroundLong noncoding RNAs (lncRNAs) have surpassed the number of protein-coding genes, yet the majority have no known function. We previously discovered 844 lncRNAs that were genetically linked to breast cancer through genome-wide association studies (GWAS). Here, we show that a subset of these lncRNAs alter breast cancer risk by modulating cell proliferation, and provide evidence that a reduced expression on one lncRNA increases breast cancer risk through aberrant DNA replication and repair.MethodsWe performed pooled CRISPR-Cas13d-based knockdown screens in breast cells to identify which of the 844 breast cancer-associated lncRNAs alter cell proliferation. We selected one of the lncRNAs that increased cell proliferation, KILR, for follow-up functional studies. KILR pull-down followed by mass spectrometry was used to identify binding proteins. Knockdown and overexpression studies were performed to assess the mechanism by which KILR regulates proliferation.ResultsWe show that KILR functions as a tumor suppressor, safeguarding breast cells against uncontrolled proliferation. The half-life of KILR is significantly reduced by the risk haplotype, revealing an alternative mechanism by which variants alter cancer risk. Mechanistically, KILR sequesters RPA1, a subunit of the RPA complex required for DNA replication and repair. Reduced KILR expression promotes breast cancer cell proliferation by increasing the available pool of RPA1 and speed of DNA replication. Conversely, KILR overexpression promotes apoptosis in breast cancer cells, but not normal breast cells.ConclusionsOur results confirm lncRNAs as mediators of breast cancer risk, emphasize the need to annotate noncoding transcripts in relevant cell types when investigating GWAS variants and provide a scalable platform for mapping phenotypes associated with lncRNAs.

Formation pathways of formic acid (HCOOH) in regions with methanol ices

We modeled the collisions between OH^+ projectiles with kinetic energies ranging from 10 to 22 eV and an amorphous cold (CH3OH)_10 substrate using Born-Oppenheimer molecular dynamics (BOMD) simulations. We conducted the simulations for a collision time of 400 femtoseconds (fs), during which we followed multiple bond-forming and breaking reactions. Here, we report four new pathways for the formation of formic acid HCOOH . We find new precursors such as CH3(OH)2+ HC(OH)2^+ CH2OH^+ and CH2(OH)2 which are essential in these pathways for the formation of formic acid. The methanodiol CH2(OH)2 and hydroxymethyl CH2OH^+ cations have previously been identified as key precursors of formaldehyde. These pathways suggest new ways to form formic acid in methanol ice mantles on dust grains, offering alternative mechanisms leading to the formation of complex organic molecules (COMs) in space.

Brics Ascendancy: Challenging Western Hegemony in a Globalized World

The global financial milieu has long been characterized by the pre-eminence of the United States dollar as the world's principal reserve currency. Nevertheless, emerging trends indicate the prospect of a paradigmatic shift wherein the dollar's status as a reserve currency may diminish. This study undertakes an in-depth analysis of the factors contributing to this potential transition, with particular emphasis on the ascent of the BRICS nations (Brazil, Russia, India, China, and South Africa) and their capability to establish a novel financial framework. Drawing upon insights from eminent scholars affiliated with prestigious institutions such as Harvard, Cambridge, Princeton, Chicago, Yale, and Oxford, this research assesses the evolving dynamics of global finance. By scrutinizing historical hegemonic patterns dating back to the 17th century, this investigation offers a comprehensive perspective on the ascendance and decline of dominant currencies and their ramifications on the international monetary system. Through meticulous examination of economic indicators, geopolitical transformations, and institutional advancements, this paper elucidates potential avenues through which the BRICS nations could challenge the hegemony of the U.S. dollar. Furthermore, it explores the feasibility of instituting alternative financial mechanisms to facilitate transactions and investments among BRICS countries and beyond, thereby mitigating dependence on the dollar-centric financial framework. This research, therefore, has culminated in the conclusion that the hegemonic status of the U.S. dollar is poised to diminish before the year 2030.

Reversible Capture Mechanism of CO2 as a Zn(II)-Methylcarbonate.

In this study, we elucidate the reaction mechanism for capturing CO2 with the ZnL1(MeOH) complex (L1 = diacetyl-2-(4-methyl-3-thiosemicarbazone)-3-(2-hydrazinatopyridine)) in a methanol solution, using density functional theory calculations. One pathway involves the protonation of ZnL1(MeOH) by methylcarbonic acid, followed by ligand exchange of MeOH with MeOCO2-. An alternative mechanism suggests a tautomerization between ZnL1(MeOH) and Zn(HL1)(OMe), followed by CO2 insertion. This latter pathway is energetically more favorable than the former and more complex than initially proposed. In fact, we unveiled that the solvent catalyzes tautomerization, as one explicit methanol molecule acts as a proton transfer agent. Then, Zn(HL1)(OMe) captures CO2, yielding a methylcarbonate bound to the metal center. The final step involves a rearrangement that leads to the cleavage of the Zn-O(Me)(COO) bond and the formation of a new Zn-O(COOMe) bond, along with the rotation of the methylcarbonate group. Furthermore, we evaluated the ligand basicity through the pKa calculated values of the Zn(II) complexes, the effects of varying the ligand from 4-methyl-thiosemicarbazone to 4-ethyl (L2), 4-phenethyl (L3), and 4-benzyl (L4) derivatives, and reversibility of the reaction in an argon environment.

Phase-separated droplets swim to their dissolution

Biological macromolecules can condense into liquid domains. In cells, these condensates form membraneless organelles that can organize chemical reactions. However, little is known about the physical consequences of chemical activity in and around condensates. Working with model bovine serum albumin (BSA) condensates, we show that droplets swim along chemical gradients. Active BSA droplets loaded with urease swim toward each other. Passive BSA droplets show diverse responses to externally applied gradients of the enzyme’s substrate and products. In all these cases, droplets swim toward solvent conditions that favor their dissolution. We call this behavior “dialytaxis”, and expect it to be generic, as conditions which favor dissolution typically reduce interfacial tension, whose gradients are well-known to drive droplet motion through the Marangoni effect. These results could potentially suggest alternative physical mechanisms for active transport in living cells, and may enable the design of fluid micro-robots.

Antecedents of Independent Directors on Joint Venture Boards

The presence of independent directors on corporate boards is often seen as an important means of monitoring to address principal-agent problems and of providing external resources and advice to management. In joint ventures (JVs), however, shareholder-management frictions can be lessened by appointing insiders to management and board positions, whereas access to valuable expertise, resources, and networks are provided by the partners themselves. A natural question, then, is why and when do partners appoint independent directors to JV boards? We argue that the appointment of independent directors to joint venture boards is primarily driven by principal-principal conflict considerations, which are unique in the joint venture context compared with conventional widely held corporations. Consistent with this argument, we find that the likelihood of appointing independent directors increases when JVs face more exchange hazards due to the competitive overlap between partners and the broader functional scope of the JV. However, given that JVs also have alternative governance mechanisms to mitigate shareholder conflicts, we also find that more complex contractual agreements can potentially substitute for independent directors on JV boards. Although relational governance is often highlighted as a key facet of JV governance, we do not find such a substitution effect for this supporting governance mechanism. Overall, our research therefore highlights several interesting domain translation issues when applying existing corporate governance insights to the joint venture setting. Our paper concludes with a call for future research on independent directors serving on JV boards, as JVs represent an organizational form that has been neglected in corporate governance research.

SwinYOLOv7: Robust ship detection in complex synthetic aperture radar images

Using satellite-based SAR (Synthetic Aperture Radar) imagery to detect and track ships is a formidable challenge. However, accurate analysis is hampered by inherent difficulties such as obscured edges, multiple targets, varying dimensions and complex backgrounds. These factors contribute to a poor signal-to-noise ratio. Various artificial intelligence models have been developed to improve these problems, especially with YOLO-based models. To overcome the above challenges and achieve robust performance, this study presents a model called SwinYOLOv7, a novel fusion of the YOLOv7 framework with the Features Pyramid Network and the Swin Transformer using ground-breaking anchor-free detection algorithms. This innovative method aims to increase the accuracy of vessel detection while reducing the impact of background clutter. The proposed model improved by YOLOv7 examined three different datasets in detail: SRSDD-v1.0, HRSID, and SSDD to optimize the performance of the model. The training process was consistently verified using superior recall, precision, and F1-score values, which can be easily compared with previous studies. The results show that the model using the Swin Transformer attention mechanism and using an image size of 640×640 achieves the highest accuracy of 96.59%. Alternative attention mechanisms, including the Squeeze-and-Excitation Network (SEnet), the Convolutional Block Attention Module (CBAM), Channel Attention (CA) and Efficient Channel Attention (ECA), deliver poorer accuracy rates. The combination of YOLOv7 and Swin Transformer yielded encouraging results that enabled the proposed model to outperform the current benchmarking models. Therefore, the proposed model provides a compelling solution to ensure accurate vessel identification in complex search and rescue scenarios.

HER2 mutation as an emerging target in advanced breast cancer.

HER2 activating mutations have emerged as oncogenic drivers and therapeutic targets in a variety of human tumors. In breast cancer, these deregulations occur at low frequency, and are mostly detected in HER2-nonamplified, metastatic disease. Preclinical evidence has clarified the role of hotspot mutations in HER2 constitutive activation, defining them as an alternative mechanism to HER2 gene amplification. Furthermore, recent clinical studies have indicated the emergence of newly acquired HER2 deregulations in significant proportions of breast cancer patients who experience disease progression following both endocrine and HER2-targeted therapies. As the involvement of HER2 mutation in therapy resistance may profoundly impact patient outcomes on successive therapies, several clinical trials are currently investigating the efficacy of various HER2-targeted drugs in HER2-mutant breast cancer. In this review, we firstly summarize the structural organization of the HER2 oncogene and its historical impact on breast cancer prognosis and therapeutic advancement. Then, we provide an overview of the frequencies and functional relevance of clinically recurrent HER2 mutations in breast cancer with a special focus on their role in therapeutic resistance. Finally, we provide a collection of the clinical trials that are currently exploring novel therapeutic approaches for this patient subset and discuss the related perspectives and challenges.

Improved mini-batch multiple augmentation for low-resource spoken word recognition

Data augmentation techniques have been useful in dealing with limited data for machine learning tasks. Recently, spectrogram data augmentation techniques have been investigated for voice conversion and sound classification tasks and have produced better results. However, applying multiple data augmentation techniques within a mini-batch has been observed to lead to performance degradation. While applying multiple augmentation methods sequentially has shown performance gains in image data, transferring this approach to spectrogram data leads to loss of acoustic information. Hence, an alternative approach is needed to effectively utilize multiple augmentation methods in the speech domain. This study addressed these challenges in low-resource settings for spoken word recognition within the mini-batch. First, we investigated the effect of data augmentation techniques. Second, we investigated the effect of multiple data augmentation techniques. Finally, we proposed a new approach that uses an alternate mechanism to utilize multiple spectrogram augmentation techniques more effectively. The results of our experiment show that the proposed approach (new pattern) outperforms the sequential approach (traditional pattern) significantly at different scales of datasets, including low-resource settings. In addition, the proposed approach achieves approximately 2x actual speedup over the sequential approach. A combination of frequency-warping and time length control augmentation methods was found to be stable and robust in performance across all datasets evaluated.

Insulating-to-conducting state transition in the bilayer Hubbard model induced by a perpendicular quench field

A many-body quantum system with varying parameters can exhibit two distinct quantum states within the same energy shell. This allows for a dynamic transition from the ground state of the pre-quench Hamiltonian to a steady state of the post-quench Hamiltonian. We investigate the dynamic response of the ground states in a two-layer half-filled Hubbard model to a perpendicular electric field. We demonstrate that the steady state exhibits conductivity when the field is in resonance with the on-site repulsion, while the initial state is a Mott-insulating state. Additionally, the two layers exhibit identical conducting behavior due to the formation of long-lived dopings, as evidenced by the charge fluctuation. The key factor in achieving this dynamic transition is the cooperative interplay between on-site interactions and the resonant field, rather than the individual roles they play. Our findings offer an alternative mechanism for field-induced conductivity in strongly correlated systems.

The StuA Transcription Factor and Alternative Splicing Mechanisms Drive the Levels of MAPK Hog1 Transcripts in the Dermatophyte Trichophyton rubrum.

Trichophyton rubrum is a human fungal pathogen that causes dermatophytosis, an infection that affects keratinized tissues. Integrated molecular signals coordinate mechanisms that control pathogenicity. Transcriptional regulation is a core regulation of relevant fungal processes. Previous RNA sequencing data revealed that the absence of the transcription factor StuA resulted in the differential expression of the MAPK-related high glycerol osmolarity gene (hog1) in T. rubrum. Here we validated the role of StuA in regulating the transcript levels of hog1. We showed through RT-qPCR that transcriptional regulation controls hog1 levels in response to glucose, keratin, and co-culture with human keratinocytes. In addition, we also detected hog1 pre-mRNA transcripts that underwent alternative splicing, presenting intron retention in a StuA-dependent mechanism. Our findings suggest that StuA and alternative splicing simultaneously, but not dependently, coordinate hog1 transcript levels in T. rubrum. As a means of preventing and treating dermatophytosis, our results contribute to the search for new potential drug therapies based on the molecular aspects of signaling pathways in T. rubrum.