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Free Radical Biology & Medicine May 2024Severe dry eye disease causes ocular surface damage, which is highly associated with mitochondrial dysfunction. Mitochondrial transcription factor A (TFAM) is essential...
Disrupted mitochondrial transcription factor A expression promotes mitochondrial dysfunction and enhances ocular surface inflammation by activating the absent in melanoma 2 inflammasome.
PURPOSE
Severe dry eye disease causes ocular surface damage, which is highly associated with mitochondrial dysfunction. Mitochondrial transcription factor A (TFAM) is essential for packaging mitochondrial DNA (mtDNA) and is crucial for maintaining mitochondrial function. Herein, we aimed to explore the effect of a decreased TFAM expression on ocular surface damage.
METHODS
Female C57BL/6 mice were induced ocular surface injury by topical administrating benzalkonium chloride (BAC). Immortalized human corneal epithelial cells (HCECs) were stimulated by tert-butyl hydroperoxide (t-BHP) to create oxidative stress damage. HCECs with TFAM knockdown were established. RNA sequencing was employed to analyze the whole-genome expression. Mitochondrial changes were measured by transmission electron microscopy, Seahorse metabolic flux analysis, mitochondrial membrane potential, and mtDNA copy number. TFAM expression and inflammatory cytokines were determined using RT-qPCR, immunohistochemistry, immunofluorescence, and immunoblotting.
RESULTS
In both the corneas of BAC-treated mice and t-BHP-induced HCECs, we observed impaired TFAM expression, accompanied by mitochondrial structure and function defects. TFAM downregulation in HCECs suppressed mitochondrial respiratory capacity, reduced mtDNA content, induced mtDNA leakage into the cytoplasm, and led to inflammation. RNA sequencing revealed the absent in melanoma 2 (AIM2) inflammasome was activated in the corneas of BAC-treated mice. The AIM2 inflammasome activation was confirmed in TFAM knockdown HCECs. TFAM knockdown in t-BHP-stimulated HCECs aggravated mitochondrial dysfunction and the AIM2 inflammasome activation, thereby further triggering the secretion of inflammatory factors such as interleukin (IL) -1β and IL-18.
CONCLUSIONS
TFAM reduction impaired mitochondrial function, activated AIM2 inflammasome and promoted ocular surface inflammation, revealing an underlying molecular mechanism for ocular surface disorders.
PubMed: 38797339
DOI: 10.1016/j.freeradbiomed.2024.05.032 -
Viruses May 2024Based on several clinical observations it was hypothesized that herpesviruses may influence the replication of human bocaviruses, the second known parvoviruses that have...
Based on several clinical observations it was hypothesized that herpesviruses may influence the replication of human bocaviruses, the second known parvoviruses that have been confirmed as human pathogens. While several cell lines support the growth of HSV-1, HBoV-1 was exclusively cultivated on air-liquid interface cultures, the latter being a rather complicated, slow, and low throughput system. One of the cell lines are T84 cells, which are derived from the lung metastasis of a colorectal tumor. In this study, we provide evidence that T84 also supports HBoV replication when cultivated as monolayers, while simultaneously being permissive for HSV-1. The cell culture model thus would enable co-infection studies of both viruses and is worth being optimized for high throughput studies with HBoV-1. Additionally, the study provides evidence for a supporting effect of HSV-1 on the replication and packaging of HBoV-1 progeny DNA into DNase-resistant viral particles.
Topics: Herpesvirus 1, Human; Humans; Virus Replication; Coinfection; Human bocavirus; Cell Line; Cell Line, Tumor; Cell Culture Techniques; Herpes Simplex; Parvoviridae Infections; Chlorocebus aethiops; Virus Cultivation
PubMed: 38793654
DOI: 10.3390/v16050773 -
Viruses May 2024Mouse adenoviruses (MAdV) play important roles in studying host-adenovirus interaction. However, easy-to-use reverse genetics systems are still lacking for MAdV. An...
Mouse adenoviruses (MAdV) play important roles in studying host-adenovirus interaction. However, easy-to-use reverse genetics systems are still lacking for MAdV. An infectious plasmid pKRMAV1 was constructed by ligating genomic DNA of wild-type MAdV-1 with a PCR product containing a plasmid backbone through Gibson assembly. A fragment was excised from pKRMAV1 by restriction digestion and used to generate intermediate plasmid pKMAV1-ER, which contained E3, fiber, E4, and E1 regions of MAdV-1. CMV promoter-controlled GFP expression cassette was inserted downstream of the pIX gene in pKMAV1-ER and then transferred to pKRMAV1 to generate adenoviral plasmid pKMAV1-IXCG. Replacement of transgene could be conveniently carried out between dual BstZ17I sites in pKMAV1-IXCG by restriction-assembly, and a series of adenoviral plasmids were generated. Recombinant viruses were rescued after transfecting linearized adenoviral plasmids to mouse NIH/3T3 cells. MAdV-1 viruses carrying GFP or firefly luciferase genes were characterized in gene transduction, plaque-forming, and replication in vitro or in vivo by observing the expression of reporter genes. The results indicated that replication-competent vectors presented relevant properties of wild-type MAdV-1 very well. By constructing viruses bearing exogenous fragments with increasing size, it was found that MAdV-1 could tolerate an insertion up to 3.3 kb. Collectively, a replication-competent MAdV-1 vector system was established, which simplified procedures for the change of transgene or modification of E1, fiber, E3, or E4 genes.
Topics: Animals; Mice; Genetic Vectors; Virus Replication; Plasmids; Adenoviridae; NIH 3T3 Cells; Cloning, Molecular; Genes, Reporter
PubMed: 38793642
DOI: 10.3390/v16050761 -
Genes May 2024Lysine acetyltransferase 8, also known as KAT8, is an enzyme involved in epigenetic regulation, primarily recognized for its ability to modulate histone acetylation.... (Review)
Review
Lysine acetyltransferase 8, also known as KAT8, is an enzyme involved in epigenetic regulation, primarily recognized for its ability to modulate histone acetylation. This review presents an overview of KAT8, emphasizing its biological functions, which impact many cellular processes and range from chromatin remodeling to genetic and epigenetic regulation. In many model systems, KAT8's acetylation of histone H4 lysine 16 (H4K16) is critical for chromatin structure modification, which influences gene expression, cell proliferation, differentiation, and apoptosis. Furthermore, this review summarizes the observed genetic variability within the gene, underscoring the implications of various single nucleotide polymorphisms (SNPs) that affect its functional efficacy and are linked to diverse phenotypic outcomes, ranging from metabolic traits to neurological disorders. Advanced insights into the structural biology of KAT8 reveal its interaction with multiprotein assemblies, such as the male-specific lethal (MSL) and non-specific lethal (NSL) complexes, which regulate a wide range of transcriptional activities and developmental functions. Additionally, this review focuses on KAT8's roles in cellular homeostasis, stem cell identity, DNA damage repair, and immune response, highlighting its potential as a therapeutic target. The implications of KAT8 in health and disease, as evidenced by recent studies, affirm its importance in cellular physiology and human pathology.
Topics: Humans; Epigenesis, Genetic; Histone Acetyltransferases; Acetylation; Histones; Polymorphism, Single Nucleotide; Animals; Chromatin Assembly and Disassembly
PubMed: 38790268
DOI: 10.3390/genes15050639 -
Genes Apr 2024Cervical cancer is among the highest-ranking types of cancer worldwide, with human papillomavirus (HPV) as the agent driving the malignant process. One aspect of the...
BACKGROUND
Cervical cancer is among the highest-ranking types of cancer worldwide, with human papillomavirus (HPV) as the agent driving the malignant process. One aspect of the infection's evolution is given by epigenetic modifications, mainly DNA methylation and chromatin alteration. These processes are guided by several chromatin remodeling complexes, including NuRD. The purpose of this study was to evaluate the genome-wide binding patterns of the NuRD complex components (MBD2 and MBD3) in the presence of active HPV16 E6 and E7 oncogenes and to determine the potential of identified genes through an experimental model to differentiate between cervical precursor lesions, with the aim of establishing their utility as biomarkers.
METHODS
The experimental model was built using the CaSki cell line and shRNA for E6 and E7 HPV16 silencing, ChIP-seq, qRT-PCR, and Western blot analyses. Selected genes' expression was also assessed in patients.
RESULTS
Several genes have been identified to exhibit altered transcriptional activity due to the influence of HPV16 E6/E7 viral oncogenes acting through the MBD2/MBD3 NuRD complex, linking them to viral infection and cervical oncogenesis.
CONCLUSIONS
The impacted genes primarily play roles in governing gene transcription, mRNA processing, and regulation of translation. Understanding these mechanisms offers valuable insights into the process of HPV-induced oncogenesis.
Topics: Humans; Mi-2 Nucleosome Remodeling and Deacetylase Complex; Uterine Cervical Neoplasms; Papillomavirus E7 Proteins; Oncogene Proteins, Viral; DNA-Binding Proteins; Female; Chromatin Assembly and Disassembly; Repressor Proteins; Cell Line, Tumor; Human papillomavirus 16; Carcinogenesis; Papillomavirus Infections; Gene Expression Regulation, Neoplastic
PubMed: 38790189
DOI: 10.3390/genes15050560 -
Epigenetics & Chromatin May 2024The three-dimensional organization of the genome plays a central role in the regulation of cellular functions, particularly in the human brain. This review explores the... (Review)
Review
The three-dimensional organization of the genome plays a central role in the regulation of cellular functions, particularly in the human brain. This review explores the intricacies of chromatin organization, highlighting the distinct structural patterns observed between neuronal and non-neuronal brain cells. We integrate findings from recent studies to elucidate the characteristics of various levels of chromatin organization, from differential compartmentalization and topologically associating domains (TADs) to chromatin loop formation. By defining the unique chromatin landscapes of neuronal and non-neuronal brain cells, these distinct structures contribute to the regulation of gene expression specific to each cell type. In particular, we discuss potential functional implications of unique neuronal chromatin organization characteristics, such as weaker compartmentalization, neuron-specific TAD boundaries enriched with active histone marks, and an increased number of chromatin loops. Additionally, we explore the role of Polycomb group (PcG) proteins in shaping cell-type-specific chromatin patterns. This review further emphasizes the impact of variations in chromatin architecture between neuronal and non-neuronal cells on brain development and the onset of neurological disorders. It highlights the need for further research to elucidate the details of chromatin organization in the human brain in order to unravel the complexities of brain function and the genetic mechanisms underlying neurological disorders. This research will help bridge a significant gap in our comprehension of the interplay between chromatin structure and cell functions.
Topics: Humans; Neurons; Chromatin; Animals; Brain; Polycomb-Group Proteins; Chromatin Assembly and Disassembly
PubMed: 38783373
DOI: 10.1186/s13072-024-00538-6 -
Nature Communications May 2024Topologically associating domains (TADs), megabase-scale features of chromatin spatial architecture, are organized in a domain-within-domain TAD hierarchy. Within TADs,...
Topologically associating domains (TADs), megabase-scale features of chromatin spatial architecture, are organized in a domain-within-domain TAD hierarchy. Within TADs, the inner and smaller subTADs not only manifest cell-to-cell variability, but also precisely regulate transcription and differentiation. Although over 20 TAD callers are able to detect TAD, their usability in biomedicine is confined by a disagreement of outputs and a limit in understanding TAD hierarchy. We compare 13 computational tools across various conditions and develop a metric to evaluate the similarity of TAD hierarchy. Although outputs of TAD hierarchy at each level vary among callers, data resolutions, sequencing depths, and matrices normalization, they are more consistent when they have a higher similarity of larger TADs. We present comprehensive benchmarking of TAD hierarchy callers and operational guidance to researchers of life science researchers. Moreover, by simulating the mixing of different types of cells, we confirm that TAD hierarchy is generated not simply from stacking Hi-C heatmaps of heterogeneous cells. Finally, we propose an air conditioner model to decipher the role of TAD hierarchy in transcription.
Topics: Benchmarking; Chromatin; Humans; Computational Biology; Software; Chromatin Assembly and Disassembly
PubMed: 38782890
DOI: 10.1038/s41467-024-48593-7 -
Journal of Clinical and Translational... May 2024Hepatitis B virus (HBV) infection is a major risk factor for cirrhosis and liver cancer, and its treatment continues to be difficult. We previously demonstrated that a...
BACKGROUND AND AIMS
Hepatitis B virus (HBV) infection is a major risk factor for cirrhosis and liver cancer, and its treatment continues to be difficult. We previously demonstrated that a dopamine analog inhibited the packaging of pregenomic RNA into capsids. The present study aimed to determine the effect of dopamine on the expressions of hepatitis B virus surface and e antigens (HBsAg and HBeAg, respectively) and to elucidate the underlying mechanism.
METHODS
We used dopamine-treated HBV-infected HepG2.2.15 and NTCP-G2 cells to monitor HBsAg and HBeAg expression levels. We analyzed interferon-stimulated gene 15 (ISG15) expression in dopamine-treated cells. We knocked down ISG15 and then monitored HBsAg and HBeAg expression levels. We analyzed the expression of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway factors in dopamine-treated cells. We used dopamine hydrochloride-treated adeno-associated virus/HBV-infected mouse model to evaluate HBV DNA, HBsAg, and HBeAg expression. HBV virus was collected from HepAD38.7 cell culture medium.
RESULTS
Dopamine inhibited HBsAg and HBeAg expression and upregulated ISG15 expression in HepG2.2.15 and HepG2-NTCP cell lines. ISG15 knockdown increased HBsAg and HBeAg expression in HepG2.2.15 cells. Dopamine-treated cells activated the JAK/STAT pathway, which upregulated ISG15 expression. In the adeno-associated virus-HBV murine infection model, dopamine downregulated HBsAg and HBeAg expression and activated the JAK-STAT/ISG15 axis.
CONCLUSIONS
Dopamine inhibits the expression of HBsAg and HBeAg by activating the JAK/STAT pathway and upregulating ISG15 expression.
PubMed: 38779516
DOI: 10.14218/JCTH.2024.00051 -
Biochemical Society Transactions Jun 2024Nucleosomes constitute the fundamental building blocks of chromatin. They are comprised of DNA wrapped around a histone octamer formed of two copies each of the four... (Review)
Review
Nucleosomes constitute the fundamental building blocks of chromatin. They are comprised of DNA wrapped around a histone octamer formed of two copies each of the four core histones H2A, H2B, H3, and H4. Nucleosomal histones undergo a plethora of posttranslational modifications that regulate gene expression and other chromatin-templated processes by altering chromatin structure or by recruiting effector proteins. Given their symmetric arrangement, the sister histones within a nucleosome have commonly been considered to be equivalent and to carry the same modifications. However, it is now clear that nucleosomes can exhibit asymmetry, combining differentially modified sister histones or different variants of the same histone within a single nucleosome. Enabled by the development of novel tools that allow generating asymmetrically modified nucleosomes, recent biochemical and cell-based studies have begun to shed light on the origins and functional consequences of nucleosomal asymmetry. These studies indicate that nucleosomal asymmetry represents a novel regulatory mechanism in the establishment and functional readout of chromatin states. Asymmetry expands the combinatorial space available for setting up complex sets of histone marks at individual nucleosomes, regulating multivalent interactions with histone modifiers and readers. The resulting functional consequences of asymmetry regulate transcription, poising of developmental gene expression by bivalent chromatin, and the mechanisms by which oncohistones deregulate chromatin states in cancer. Here, we review recent progress and current challenges in uncovering the mechanisms and biological functions of nucleosomal asymmetry.
Topics: Nucleosomes; Histones; Humans; Animals; Protein Processing, Post-Translational; Chromatin; Chromatin Assembly and Disassembly
PubMed: 38778762
DOI: 10.1042/BST20230877 -
Nature Structural & Molecular Biology May 2024Hexasomes are non-canonical nucleosomes that package DNA with six instead of eight histones. First discovered 40 years ago as a consequence of transcription, two... (Review)
Review
Hexasomes are non-canonical nucleosomes that package DNA with six instead of eight histones. First discovered 40 years ago as a consequence of transcription, two near-atomic-resolution cryo-EM structures of the hexasome in complex with the chromatin remodeler INO80 have now started to unravel its mechanistic impact on the regulatory landscape of chromatin. Loss of one histone H2A-H2B dimer converts inactive nucleosomes into distinct and favorable substrates for ATP-dependent chromatin remodeling.
Topics: Chromatin Assembly and Disassembly; Nucleosomes; Histones; Cryoelectron Microscopy; Models, Molecular; Humans; Saccharomyces cerevisiae Proteins; DNA
PubMed: 38769465
DOI: 10.1038/s41594-024-01278-7