Transcriptional Protein Research Articles

Transcriptomic Regulation by Astrocytic m6A Methylation in the mPFC.

Astrocytes, the most prevalent type of glial cells, have been found to play a crucial part in numerous physiological functions. By offering metabolic and structural support, astrocytes are vital for the proper functioning of the brain and regulating information processing and synaptic transmission. Astrocytes located in the medial prefrontal cortex (mPFC) are highly responsive to environmental changes and have been associated with the development of brain disorders. One of the primary mechanisms through which the brain responds to environmental factors is epitranscriptome modification. M6-methyladenosine methylation is the most prevalent internal modification of eukaryotic messenger RNA (mRNA), and it significantly impacts transcript processing and protein synthesis. However, the effects of m6A on astrocyte transcription and function are still not well understood. Our research demonstrates that ALKBH5, an RNA demethylase of m6A found in astrocytes, affects gene expression in the mPFC. These findings suggest that further investigation into the potential role of astrocyte-mediated m6A methylation in the mPFC is warranted.

BRD9 promotes the malignant phenotype of thyroid cancer by activating the MAPK/ERK pathway

Thyroid cancer is one of the most common endocrine gland malignancies in China. During gene transcription, the bromodomain and extraterminal domain (BET) proteins perform epigenome interpretation tasks. Bromodomain-containing protein 9 (BRD9) is one of the BET family members. Increasing evidence has implicated that BRD9 plays significant roles in multiple malignancies. However, its role in thyroid cancer is still not fully understood. In this research, our results demonstrated that high expression of BRD9 can facilitate the malignant phenotype of thyroid cancer cell lines, while low expression of BRD9 can impede the malignant phenotype of thyroid cancer cell lines. Pharmacologically, I-BRD9 treatment inhibits the proliferation and promotes the rate of apoptosis in thyroid cancer cell lines. Moreover, our results also revealed that BRD9 promoted xenograft tumor growth. In addition, our study showed that the expression of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) pathway-related proteins was decreased in BRD9 knockdown thyroid cancer cells, such as Raf, ERK, p-ERK, c-Fos, and c-Myc, which could be significantly reversed by overexpressing the BRD9 in different thyroid cancer cells. After the specific inhibitor of ERK (SCH772984) was applied to thyroid cancer cells (BCPAP cells) overexpressing the BRD9 gene, the results suggested that SCH772984 reverses the high expression of MAPK/ERK pathway-associated protein in BCPAP cells (over-expression BRD9 cells). In conclusion, this study demonstrated that BRD9 was highly expressed in serum and malignant tumor tissues of thyroid cancer patients and further promoted the development of the malignant phenotype of thyroid cancer by activating the MAPK/ERK signaling pathway.

Regulation of ER stress-induced apoptotic and inflammatory responses via YAP/TAZ-mediated control of the TRAIL-R2/DR5 signaling pathway.

In tumors, cancer cells are frequently exposed to adverse environmental conditions that result in endoplasmic reticulum (ER) stress. Mechanical signals emerging from extracellular matrix (ECM) rigidity and cell shape regulate the activity of transcriptional co-activators Yes-associated protein (YAP) and its paralog Transcriptional Coactivator with PDZ-binding motif (TAZ). However, the role of ECM rigidity and YAP/TAZ in tumor cell fate decisions under ER stress remains relatively unexplored. Our results suggest that the YAP/TAZ system plays an important role in the control of ER stress-induced cell death by mechanical signaling arising from ECM stiffness in tumor cells. Mechanistically, YAP/TAZ regulates apoptosis induced by ER stress in tumor cells by controlling the activation of the TRAIL-R2/DR5-mediated extrinsic apoptotic pathway through a dual mechanism. On the one hand, the YAP/TAZ system prevents intracellular TRAIL-R2/DR5 clustering in tumor cells. On the other hand, it inhibits cFLIP down-regulation in tumor cells experiencing ER stress. In addition, YAP/TAZ controls the expression of pro-inflammatory interleukin-8 (IL-8/CXCL8) in tumor cells undergoing ER stress by a TRAIL-R2/DR5/caspase-8-dependent mechanism. Although other mechanisms may also be involved in controlling cell death and inflammation in tumor cells facing environmental stress, our results support a model in which regulation of the subcellular localization and activity of the YAP/TAZ transcriptional co-activators could contribute to the microenvironmental control of cell fate decisions in tumor cells undergoing ER stress.

Identification of the BBX gene family in blueberry at different chromosome ploidy levels and fruit development and response under stress

BackgroundBlueberry (Vaccinium spp.) fruits are rich in flavonoids such as anthocyanins and have a high nutritional value. The zinc finger protein transcription factor B-box (BBX) plays important roles in plant growth and development, hormone response, abiotic stress, and anthocyanin accumulation. However, studies on the BBX family in blueberry are lacking.ResultsIn total, 83 VcBBX and 24 VdBBX genes were identified in tetraploid and diploid blueberry, respectively. A correlation was observed between the number of BBX genes in blueberry and chromosome ploidy. Gene loss and specific replication during blueberry evolution may lead to an imbalance of quantitative relationship between VcBBX and VdBBX genes. The analysis of transcriptome and quantitative reverse transcription–polymerase chain reaction data revealed that the expression pattern of BBX genes depended on the developmental stage of blueberry fruit. Gibberellin inhibited the expression of most VcBBX genes. Abscisic acid promoted the expression of some members of the BBX family. The expression levels of VcBBX15b4, VcBBX21a1, and VcBBX30a in blueberry leaves were significantly downregulated under blue light treatment, whereas that of VcBBX15c3 was significantly upregulated under red light treatment.ConclusionIn total, 83 VcBBX and 24 VdBBX genes were identified in 2 types of blueberries. Fruit development and transcription profiles under different stresses were analyzed. These findings will support further investigation of how BBX genes are involved in regulating hormone treatment and light stress during the growth and development of blueberry.

GhRAP2.4 enhances drought tolerance by positively regulating the strigolactone receptor GhD14 expression in cotton (Gossypium hirsutum L.).

Drought poses significant challenges to crop productivity, necessitating a deeper understanding of plant adaptive mechanisms. Strigolactones (SLs), a class of phytohormones, have been recognized as crucial regulators in plant responses to drought, yet the specific role of SL receptor in drought tolerance in cotton (Gossypium hirsutum L.) remains underexplored. In this study, we identified and characterized DWARF14 (GhD14), a SL receptor in cotton. Silencing GhD14 in cotton compromised drought tolerance by reducing leaf relative water content and chlorophyll content, slowing stomatal closure, increasing reactive oxygen species levels, and decreasing antioxidant enzyme activities. Conversely, overexpression of GhD14 in Arabidopsis d14 mutants rescued their drought-sensitive phenotype. Further, we identified a 197-bp fragment (-697 to -894 bp) in the GhD14 promoter that plays a crucial role in the drought stress response. RELATED TO APETALA 2.4 (GhRAP2.4), a dehydration responsive element binding protein (DREB) transcription factor, binds directly to the GhD14 promoter, enhancing its transcription under drought conditions. Silencing GhRAP2.4 in cotton resulted in reduced drought tolerance. This study not only elucidates the molecular interplay between GhRAP2.4 and GhD14 in cotton's drought response but also provides a potential target for genetic modification to improve drought resilience in crops.

Exploring ABI5 regulation: Post-translational control and cofactor interactions in ABA signaling.

Abscisic acid insensitive 5 (ABI5) is a pivotal transcription factor in abscisic acid (ABA) signaling, playing an essential role in plant growth and responses to abiotic stress. This key regulator is subject to multifaceted regulation, especially on post-translational mechanisms. Recent research has shed light on the post-translational regulation of ABI5, encompassing both post-translational modifications (PTMs) and the modulation of its transcriptional activity. In this review, we provide a comprehensive overview of the current knowledge surrounding the post-translational regulation of ABI5, along with the influence of various cofactors on its transcriptional activity and protein stability. The potential biological roles of PTMs of ABI5 in the context of ABA signaling and plant stress responses are also explored. As ABI5 is one of the most extensively studied proteins in the context of plant ABA signaling and environmental stress responses, a sophisticated and precise understanding of the regulatory mechanisms that govern ABI5 is not only beneficial for its application in genetic engineering but also helpful for our exploration in the fundamental principles of post-translational regulation.

Estrogen and glucocorticoid promote the lactoferrin synthesis and secretion ability of bovine mammary epithelial cells through ER and GR signaling pathways.

Lactoferrin (LF) is an innate immunity glycoprotein with antibacterial, anti-inflammatory, antiviral, anti-tumor, and autoantibody activity-enhancing properties. Steroid hormones are essential for development and lactation in the dairy cow mammary gland, and act through binding to receptors that drive gene transcription. However, it remains unclear whether steroid hormone receptors play roles in LF synthesis in bovine mammary epithelial cells (BMECs). In this study, we investigated the direct effects of estrogen and glucocorticoid on LF synthesis and secretion by BMECs. The results show that treatment of BMECs with estrogen (17-β-estradiol, E2) and glucocorticoid (hydrocortisone) significantly promoted cell proliferation. Furthermore, E2 or hydrocortisone increased the expression levels of estrogen receptor (ER) and glucocorticoid receptor (GR), and stimulated the synthesis and secretion of LF in BMECs. Treatment of BMECs with various inhibitors (fulvestrant, mifepristone, and pimozide) decreased LF gene transcript and LF protein levels. It was concluded that fulvestrant and mifepristone inhibit LF transcription and translation via inhibiting ER and GR, respectively. Our data indicate that E2 and hydrocortisone regulate LF protein synthesis through the ER and GR signaling pathways. These results provide new information about the regulation of the synthesis of functional proteins in milk.

In vitro and in vivo anti-inflammatory and antinociceptive activities of a synthetic hydrangenol derivative: 5-hydroxy-2-(4-hydroxyphenyl)-4H-chromen-4-one.

In the present study, we developed and synthesized novel hydrangenol derivatives and featured their anti-inflammatory activities. Especially, a synthetic derivative 11 (compound 11), which possesses the 4H-1-benzopyran-4-one moiety, 5-hydroxyl group in A-ring, and 4'-hydroxyl group in B-ring, most dominantly downregulated nitric oxide (NO) and prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. In addition, compound 11 suppressed the inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) expression by inhibiting nuclear factor kappa-B (NF-κB), activator protein 1 (AP-1), and signal transducer and activator of transcription protein (STAT) pathways in LPS-provoked RAW264.7 macrophages. Additionally, we confirmed that compound 11 had better plasma stability than hydrangenol with a plasma-labile δ-valerolactone moiety. In carrageenan-induced rats, compound 11 potently reduced paw inflammation (as measured by paw volume, width, and thickness) by inhibiting the iNOS and COX-2 expression in paw tissue, thereby reducing inflammatory pain. All things considered, as compound 11 shows anti-inflammatory and antinociceptive properties, converting metabolically unstable hydrangenol into a stable compound 11 could be a promising strategy for developing new drugs.

Identification of Novel Diagnostic Biomarkers in Triple-Negative Breast Cancer Through Analysis of Polymorphic SNPs and APA Events

Background: As a subtype of breast cancer, triple-negative breast cancer (TNBC) exhibits unique pathological phenotypes and severe morbidity trends. New evidence suggests that aberrant alternative polyadenylation (APA) events can be regulated by single nucleotide polymorphisms (SNPs) and are associated with breast cancer. The study aimed to identify the APA-associated susceptibility SNP in TNBC, which may be useful in screening and treatment. Methods: The RNA sequencing data is from 285 tumor tissues and 66 normal tissues of TNBC patients, accessed from the NCBI dataset FUSCCTNBC (Accession: PRJNA486023). We analyzed gene expression levels, APA events, and APA-associated SNPs, and explored their relationships and influences on TNBC. Results: Our study revealed significant differences in both gene expression and APA events between tumor and normal tissues of TNBC patients. The differentially expressed genes are enriched in protein transcription, folding, localization, and targeting. apaQTL analysis indicated significant associations between APA events of genes and SNPs. We found that the APA event of the transmembrane p24 trafficking protein 9 (TMED9) is highly related to the SNP rs3749822, where the G allele would decrease the Poly-A length of TMED9 and increase its expression level. Conclusion: The study elucidates the significant association between SNP rs3749822 and the APA event of the TMED9 gene, as well as their influences on TNBC, highlighting the susceptibility of SNP rs3749822 allele G for TNBC. Our findings provide new directions for further exploration of SNPs affecting APA events, aiding in identifying disease-susceptible populations.

Functional Role of Bap170 Domains in Enhancer-Dependent Gene Activity in Drosophila melanogaster.

The Bap170 subunit of the SWI/SNF chromatin remodeler exhibits activator functions when artificially recruited to the LacZ reporter promoter in enhancer-dependent transcription. In this study, the functional significance of Bap170 protein domains in reporter activation was analyzed. Deletion of the ARID domain does not reduce Bap170 activity. Increased expression of the LacZ reporter was observed in the form of Bap170 without a region that includes LXXLL motifs. Deletions of the central (RFX domain and IDRs) and C-terminal region (zinc fingers) of Bap170 lead to a significant decrease in transgene expression. Apparently, these regions of Bap170 are critical for the function of this protein in enhancer-dependent transcription.

A window into intracellular events in myositis through subcellular proteomics

Objective and designIdiopathic inflammatory myopathies (IIM) are a heterogeneous group of inflammatory muscle disorders of unknown etiology. It is postulated that mitochondrial dysfunction and protein aggregation in skeletal muscle contribute to myofiber degeneration. However, molecular pathways that lead to protein aggregation in skeletal muscle are not well defined.SubjectsHere we have isolated membrane-bound organelles (e.g., nuclei, mitochondria, sarcoplasmic/endoplasmic reticulum, Golgi apparatus, and plasma membrane) from muscle biopsies of normal (n = 3) and muscle disease patients (n = 11). Of the myopathy group, 10 patients displayed mitochondrial abnormalities (IIM (n = 9); mitochondrial myopathy (n = 1)), and one IIM patient did not show mitochondrial abnormalities (polymyositis).MethodsGlobal proteomic analysis was performed using an Orbitrap Fusion mass spectrometer. Upon unsupervised clustering, normal and mitochondrial myopathy muscle samples clustered separately from IIM samples.ResultsWe have confirmed previously known protein alterations in IIM and identified several new ones. For example, we found differential expression of (i) nuclear proteins that control cell division, transcription, RNA regulation, and stability, (ii) ER and Golgi proteins involved in protein folding, degradation, and protein trafficking in the cytosol, and (iii) mitochondrial proteins involved in energy production/metabolism and alterations in cytoskeletal and contractile machinery of the muscle.ConclusionsOur data demonstrates that molecular alterations are not limited to protein aggregations in the cytosol (inclusions) and occur in nuclear, mitochondrial, and membrane compartments of IIM skeletal muscle.

Therapeutic Effects of Natural Products in the Treatment of Chronic Diseases: The Role in Regulating KEAP1-NRF2 Pathway.

Oxidative stress represents a pivotal mechanism in the pathogenesis of numerous chronic diseases. The Kelch-like ECH-associated protein 1-transcription factor NF-E2 p45-related factor 2 (KEAP1-NRF2) pathway plays a crucial role in maintaining redox homeostasis and regulating a multitude of biological processes such as inflammation, protein homeostasis, and metabolic homeostasis. In this paper, we present the findings of recent studies on the KEAP1-NRF2 pathway, which have revealed that it is aberrantly regulated and induces oxidative stress injury in a variety of diseases such as neurodegenerative diseases, cardiovascular diseases, metabolic diseases, respiratory diseases, digestive diseases, and cancer. Given this evidence, targeting KEAP1-NRF2 represents a highly promising avenue for developing therapeutic strategies for chronic diseases, and thus the development of appropriate therapeutic strategies based on the targeting of the NRF2 pathway has emerged as a significant area of research interest. This paper highlights an overview of current strategies to modulate KEAP1-NRF2, as well as recent advances in the use of natural compounds and traditional Chinese medicine, with a view to providing meaningful guidelines for drug discovery and development targeting KEAP1-NRF2. Additionally, it discusses the challenges associated with harnessing NRF2 as a therapeutic target.

Molecular and functional profiling unravels targetable vulnerabilities in colorectal cancer.

Colorectal cancer (CRC) patients with microsatellite-stable (MSS) tumors are mostly treated with chemotherapy. Clinical benefits of targeted therapies depend on mutational states and tumor location. Many tumors carry mutations in KRAS proto-oncogene, GTPase (KRAS) or B-Raf proto-oncogene, serine/threonine kinase (BRAF), rendering them more resistant to therapies. We performed whole-exome sequencing and RNA-Sequencing of 28 tumors of the Athens Comprehensive Cancer Center CRC cohort, and molecularly characterized CRC patients based on their microsatellite instability (MSI) status, single-nucleotide variations (SNVs)/copy number alterations (CNAs), and pathway/transcription factor activities at the individual patient level. Variants were classified using a computational score for integrative cancer variant annotation and prioritization. Complementing this with public multi-omics datasets, we identified activation of transforming growth factor beta (TGFβ) signaling to be more strongly activated in MSS patients, whereas Janus kinase (JAK)-signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase (MAPK) molecular cascades were activated specifically in MSI tumors. We unraveled mechanisms consistently perturbed in the transcriptional and mutational circuits and identified Runt-related transcription factors (RUNX transcription factors) as putative biomarkers in CRC, given their role in the regulation of pathways involved in tumor progression and immune evasion. Assessing the immunogenicity of CRC tumors in the context of RAS/RAF mutations and MSI/MSS status revealed a critical impact that KRAS mutations have on immunogenicity, particularly in the MSS patient subgroup, with implications for diagnosis and treatment.

Simultaneous aerobic and anaerobic respiration in hot spring chemolithotrophic bacteria

Aerobic and anaerobic organisms and their functions are spatially or temporally decoupled at scales ranging from individual cells to ecosystems and from minutes to hours. This is due to competition for energy substrates and/or biochemical incompatibility with oxygen (O2). Here we report a chemolithotrophic Aquificales bacterium, Hydrogenobacter, isolated from a circumneutral hot spring in Yellowstone National Park (YNP) capable of simultaneous aerobic and anaerobic respiration when provided with hydrogen (H2), elemental sulfur (S0), and O2. Cultivation experiments demonstrated that simultaneous aerobic and anaerobic respiration enhanced growth rates and final cell concentrations when compared to those grown aerobically or anaerobically. Consumption of O2 measured via gas chromatography and detection of transcripts for proteins involved in S0 and O2 reduction in H2/S0/O2-grown cultures confirmed co-occurring aerobic and anaerobic metabolism. This aerobic, S0-reducing metabolism is suggested to provide a competitive advantage in environments where O2 availability is low and variable. Genomic data indicating the prevalence of proteins allowing for this hybrid form of energy metabolism among bacteria and archaea suggest it to be widespread but previously overlooked due to rapid, O2-dependent abiotic oxidation of produced sulfide. These observations challenge existing paradigms of strict delineations between aerobic and anaerobic metabolism.

Host microRNA-31-5p represses oncogenic herpesvirus lytic reactivation by restricting the RNA-binding protein KHDRBS3-mediated viral gene expression.

Oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV), an etiological agent of Kaposi's sarcoma and primary effusion lymphoma, employs a biphasic life cycle consisting of latency and lytic replication to achieve lifelong infection. Despite its essential role in KSHV persistence and tumorigenicity, much remains unknown about how KSHV lytic reactivation is regulated. Leveraging high-throughput transcriptomics, we identify microRNA-31-5p (miR-31-5p) as a key regulator of KSHV lytic reactivation capable of restricting KSHV entry into the lytic replication cycle. Ectopic expression of miR-31-5p impairs KSHV lytic gene transcription and production of lytic viral proteins, culminating in dramatic reduction of infectious virion production during KSHV reactivation. miR-31-5p overexpression also markedly reduces the expression of critical viral early genes, including the master regulator of the latent-lytic switch, KSHV replication and transcription activator (RTA) protein. Through mechanistic studies, we demonstrate that miR-31-5p represses KSHV lytic reactivation by directly targeting the KH domain protein KHDRBS3, an RNA-binding protein known to regulate RNA processing including alternative splicing. Our study highlights KHDRBS3 as an essential proviral host factor that is key to the successful completion of KSHV lytic replication and suggests its novel function in viral lytic gene transcription during KSHV reactivation. Taken together, these findings reveal a previously unrecognized role for the miR-31-5p/KHDRBS3 axis in regulating the KSHV latency-lytic replication switch and provide insights into gene expression regulation of lytic KSHV, which may be leveraged for lytic cycle-targeted therapeutic strategies against KSHV-associated malignancies.

P0099 Histone H4 lysine 12 lactylation in CD4+ T cells promotes the progression of Ulcerative Colitis through PKM2/glycolysis loop and PKM2/STAT3 signaling pathway

Abstract Background Immune dysfunction- the imbalance of Th17/Treg ratio is the main pathogenic factor of ulcerative colitis (UC). Histone lactylation is a new protein modification and could regulate immune function. However, the roles of histone lactylation in the naïve CD4+ T cell differentiation and UC progression remain unclear. Methods We employed a mouse model to elucidate the mechanism by which lactic acid facilitates the progression of ulcerative colitis through the inhibition of PKM2 and targeted knockout of Pkm2 in CD4+ T cells. Results Our study shows a high level of H4K12la in CD4+ T cells at the intestinal inflammatory sites in UC, which is specifically enriched at the promoters of glycolytic genes including pyruvate kinase 2 (PKM2). Then PKM2 can activate the transcriptional activation protein 3 (STAT3) signaling pathway, thereby inducing the differentiation of naïve CD4+ T cells into Th17 cells and inhibiting Treg cell differentiation, and cause sustained release of pro-inflammatory cytokines, which finally exacerbates intestinal inflammation. In addition, as a key glycolysis enzyme, the upregulation of PKM2 expression could accelerate more lactate production in a positive feedback way. Both pharmacologic inhibition of PKM2 and CD4+ T cell-specific ablation of Pkm2 could block lactate production and then downregulate the ratio of Th17/Treg to alleviate colitis. Conclusion The study demonstrate the pro-inflammatory role of H4K12la in CD4+ T cells, and PKM2 may be a potential target for the treatment of UC.

Chimerism: A whole new perspective in gene regulation.

The diversity of molecular entities emerging from a single gene are recognized. Several studies have thus established the cellular role(s) of transcript variants and protein isoforms. A step ahead in challenging the central dogma towards expanding molecular diversity is the identification of fusion genes, chimeric transcripts and chimeric proteins that harbor sequences from more than one gene. The mechanisms for generation of chimeras largely follow similar patterns across all levels of gene regulation but also have interdependence and mutual exclusivity. Whole genome and RNA-seq technologies supported by development of computational algorithms and programs for processing datasets have increasingly enabled the identification of fusion genes and chimeric transcripts, while the discovery of chimeric proteins is as yet more subtle. Earlier thought to be associated with cellular transformation, the contribution of chimeric molecules to normal physiology is also realized and found to influence the expression of their parental genes and regulate cellular pathways. This review offers a collective and comprehensive overview of cellular chimeric entities encompassing the mechanisms involved in their generation, insights on their evolution, functions in gene regulation and their current and novel clinical applications.

The Potassium Utilization Gene Network in Brassica napus and Functional Validation of BnaZSHAK5.2 Gene in Response to Potassium Deficiency.

Potassium, an essential inorganic cation, is crucial for the growth of oil crops like Brassica napus L. Given the scarcity of potassium in soil, enhancing rapeseed's potassium utilization efficiency is of significant importance. This study identified 376 potassium utilization genes in the genome of B. napus ZS11 through homologous retrieval, encompassing 7 functional and 12 regulatory gene families. These genes are unevenly distributed across 19 chromosomes, and the proteins encoded by these genes are mainly localized in the cell membrane, vacuoles, and nucleus. Microsynteny analysis highlighted the role of small-scale replication events and allopolyploidization in the expansion of potassium utilization genes, identifying 77 distinct types of cis-acting elements within their promoter regions. The regulatory mechanisms of potassium utilization genes were provided by analyses of transcription factors, miRNA, and protein interaction networks. Under low potassium stress, the potassium utilization genes, particularly those belonging to the KUP and CBL families, demonstrate pronounced co-expression. RNA-seq and RT-qPCR analysis identified the BnaZSHAK5.2 gene, which is a high-affinity potassium ion transporter, playing a crucial role in the stress response to potassium deficiency in B. napus, as its expression is strongly induced by low potassium stress. A functional complementation study demonstrates that the BnaZSHAK5.2 gene could rescue the primary root growth of the Athak5 mutant under low potassium conditions, confirming its role in response to low potassium stress by sustaining root development.

Autoinducer-2 enhances the defense of Vibrio furnissii against oxidative stress and DNA damage by modulation of c-di-GMP signaling via a two-component system.

As a universal language across the bacterial kingdom, the quorum sensing signal autoinducer-2 (AI-2) can coordinate many bacterial group behaviors. However, unknown AI-2 receptors in bacteria may be more than what has been discovered so far, and there are still many unknown functions for this signal waiting to be explored. Here, we have identified a membrane-bound histidine kinase of the pathogenic bacterium Vibrio furnissii, AsrK, as a receptor that specifically detects AI-2 under low boron conditions. In contrast with another well-known AI-2 receptor LuxP that recognizes the borated form of AI-2, AsrK is found to show higher affinity with AI-2 under borate-depleted conditions, and thus boron has a negative effect on AI-2 sensing by AsrK in regulation of the biofilm and motility phenotypes. AI-2 binds to the extracytoplasmic dCache_1 domain of AsrK to inhibit its autokinase activity, thus decreasing the phosphorylation level of its cognate response regulator AsrR and activating the phosphodiesterase activity of AsrR to degrade the cellular second messenger cyclic di-GMP (c-di-GMP). AI-2 perception by the AsrK-AsrR system remarkably reduces intracellular c-di-GMP levels and enhances tolerance of V. furnissii to oxidative stress and DNA damage by upregulating the transcription of universal stress proteins including UspA1, UspA2, and UspE. Our study reveals a previously unrecognized mechanism for AI-2 detection in bacteria and also provides new insights into the important role of AI-2 in bacterial defense against oxidative stress and DNA damage.IMPORTANCEThe QS signal AI-2 is widely synthesized in bacteria and has been implicated in the regulation of numerous bacterial group behaviors. However, in contrast to the wide distribution of this signal, its receptors have only been found in a small number of bacterial species, and the underlying mechanisms for the detection of and response to AI-2 remain elusive in most bacteria. It is worth noting that the periplasmic protein LuxP is the uniquely identified receptor for AI-2 in Vibrio spp. Here, we identify a second type of AI-2 receptor, a membrane-bound histidine kinase with a periplasmic dCache_1 sensory domain, in a member of the genus Vibrio, and thus show that AI-2 enhances the defense of V. furnissii against oxidative stress and DNA damage by modulation of c-di-GMP signaling via the AsrK-AsrR two-component system. Our results reveal a previously unrecognized AI-2 sensing mechanism and expand our understanding of the physiological roles of AI-2 in bacteria.

Pyrroloquinoline Quinone Improved Boar Sperm Quality via Maintaining Mitochondrial Function During Cryopreservation.

Due to oxidative damage and mitochondrial dysfunction, boar semen cryopreservation remains a significant challenge. This study investigates the effects of pyrroloquinoline quinone (PQQ), a mitochondrial-targeted antioxidant, on the post-thaw boar sperm quality during cryopreservation. Boar semen was diluted in a freezing extender containing different concentrations of PQQ (0, 10, 100, 1000, 10,000 nM). After freezing-thawing, the sperm motility, viability, acrosome integrity, mitochondrial activity, adenosine triphosphate (ATP) levels, DNA integrity, malondialdehyde (MDA) levels, reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity, mitochondrial transcription proteins levels, and fertilization capacity were assessed. The results show that 1000 nM PQQ supplementation to the freezing extender significantly enhanced post-thaw sperm motility, viability, and acrosome integrity compared to the control (p < 0.05). Additionally, 1000 nM PQQ increased mitochondrial membrane potential (MMP) and ATP levels, while decreasing MDA and mitochondrial ROS levels, and reducing DNA damage (p < 0.05). Furthermore, the levels of mitochondrial-encoded proteins were significantly elevated in the 1000 nM PQQ group compared to the control (p < 0.05). Interestingly, sperm in the 1000 nM PQQ group showed a higher binding rate to oviductal epithelial cells and the zona pellucida (ZP), indicating higher fertilization potential. These findings suggest that the use of mitochondria-target antioxidant, PQQ, can improve post-thaw boar sperm quality and fertilization via its capacity to reduce oxidative stress and protect mitochondrial function.