Chlamydia trachomatis induces lncRNA MIAT upregulation to regulate mitochondria-mediated host cell apoptosis and chlamydial development.
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ABSTRACT:
SUBMITTER: Luo F
PROVIDER: S-EPMC8742237 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:UnlabelledThe Scc4 protein (CT663) of the pathogenic bacterium Chlamydia has been described as a type III secretion (T3S) chaperone as well as an inhibitor of RNA polymerase. To examine if these roles are connected, we first investigated physical interactions between Chlamydia trachomatis Scc4 and the T3S chaperone Scc1 and a T3S substrate, CopN. In a yeast 3-hybrid assay, Scc4, Scc1, and CopN were all required to detect an interaction, which suggests that these proteins form a trimolecular complex. We also detected interactions between any two of these three T3S proteins in a pulldown assay using only recombinant proteins. We next determined whether these interactions affected the function of Scc4 as an inhibitor of RNA transcription. Using Escherichia coli as a heterologous in vivo system, we demonstrated that expression of C. trachomatis Scc4 led to a drastic decrease in transcript levels for multiple genes. However, coexpression of Scc4 with Scc1, CopN, or both alleviated Scc4-mediated inhibition of transcription. Scc4 expression also severely impaired E. coli growth, but this growth defect was reversed by coexpression of Scc4 with Scc1, CopN, or both, suggesting that the inhibitory effect of Scc4 on transcription and growth can be antagonized by interactions between Scc4, Scc1, and CopN. These findings suggest that the dual functions of Scc4 may serve as a bridge to link T3S and the regulation of gene expression in Chlamydia.ImportanceThis study investigates a novel mechanism for regulating gene expression in the pathogenic bacterium Chlamydia. The Chlamydia type III secretion (T3S) chaperone Scc4 has been shown to inhibit transcription by RNA polymerase. This study describes physical interactions between Scc4 and the T3S proteins Scc1 and CopN. Furthermore, Chlamydia Scc1 and CopN antagonized the inhibitory effects of Scc4 on transcription and growth in a heterologous Escherichia coli system. These results provide evidence that transcription in Chlamydia can be regulated by the T3S system through interactions between T3S proteins.
| S-EPMC4573728 | biostudies-literature
Project description:Human herpesvirus-6 (HHV-6) exists in latent form either as a nuclear episome or integrated into human chromosomes in more than 90% of healthy individuals without causing clinical symptoms. Immunosuppression and stress conditions can reactivate HHV-6 replication, associated with clinical complications and even death. We have previously shown that co-infection of Chlamydia trachomatis and HHV-6 promotes chlamydial persistence and increases viral uptake in an in vitro cell culture model. Here we investigated C. trachomatis-induced HHV-6 activation in cell lines and fresh blood samples from patients having Chromosomally integrated HHV-6 (CiHHV-6). We observed activation of latent HHV-6 DNA replication in CiHHV-6 cell lines and fresh blood cells without formation of viral particles. Interestingly, we detected HHV-6 DNA in blood as well as cervical swabs from C. trachomatis-infected women. Low virus titers correlated with high C. trachomatis load and vice versa, demonstrating a potentially significant interaction of these pathogens in blood cells and in the cervix of infected patients. Our data suggest a thus far underestimated interference of HHV-6 and C. trachomatis with a likely impact on the disease outcome as consequence of co-infection.
| S-EPMC3631192 | biostudies-literature
Project description:BackgroundrRNA adenine dimethyltransferases, represented by the Escherichia coli KsgA protein, are highly conserved phylogenetically and are generally not essential for growth. They are responsible for the post-transcriptional transfer of two methyl groups to two universally conserved adenosines located near the 3'end of the small subunit rRNA and participate in ribosome maturation. All sequenced genomes of Chlamydia reveal a ksgA homolog in each species, including C. trachomatis. Yet absence of a S-adenosyl-methionine synthetase in Chlamydia, the conserved enzyme involved in the synthesis of the methyl donor S-adenosyl-L-methionine, raises a doubt concerning the activity of the KsgA homolog in these organisms.ResultsLack of the dimethylated adenosines following ksgA inactivation confers resistance to kasugamycin (KSM) in E. coli. Expression of the C. trachomatis L2 KsgA ortholog restored KSM sensitivity to the E. coli ksgA mutant, suggesting that the chlamydial KsgA homolog has specific rRNA dimethylase activity. C. trachomatis growth was sensitive to KSM and we were able to isolate a KSM resistant mutant of C. trachomatis containing a frameshift mutation in ksgA, which led to the formation of a shorter protein with no activity. Growth of the C. trachomatis ksgA mutant was negatively affected in cell culture highlighting the importance of the methylase in the development of these obligate intracellular and as yet genetically intractable pathogens.ConclusionThe presence of a functional rRNA dimethylase enzyme belonging to the KsgA family in Chlamydia presents an excellent chemotherapeutic target with real potential. It also confirms the existence of S-adenosyl-methionine--dependent methylation reactions in Chlamydia raising the question of how these organisms acquire this cofactor.
| S-EPMC2807437 | biostudies-literature
Project description:Atherosclerotic cardio-cerebrovascular disease and death remain the leading cause of morbidity and mortality worldwide. Defective efferocytosis, the clearance of apoptotic cells by macrophages, is thought to lead to increased inflammation and necrotic core formation in atherosclerotic lesions. However, very little is known about the role of long noncoding RNA (lncRNA) during this process. Here we show that lncRNA myocardial infarction associated transcript (MIAT) was markedly elevated in the serum of patients with symptoms of vulnerable atherosclerotic plaque and the macrophages of necrotic cores in an advanced atherosclerosis mouse model. MIAT knockdown attenuated atherosclerosis progression, reduced necrotic core size, and increased plaque stability in vivo. Furthermore, MIAT knockdown promoted clearance of apoptotic cells by macrophages in vivo and in vitro. Mechanistic studies revealed that MIAT acted as a micro RNA (miRNA) sponge to positively modulate the expression of anti-phagocytic molecule CD47 through sponging miR-149-5p. Together, these findings identified a macrophage MIAT/miR-149-5p /CD47 pathway as a key factor in the development of necrotic atherosclerotic plaques.
| S-EPMC6372637 | biostudies-literature
Project description:BackgroundCatechin protects heart from myocardial ischaemia/reperfusion (MI/R) injury. However, whether catechin inhibits H/R-induced myocardial cell apoptosis is largely unknown.ObjectiveThis study aims to investigate the underlying mechanism of catechin in inhibiting the apoptosis of H/R-induced myocardial cells.MethodsLncRNA MIAT expression was detected by qRT-PCR. Cell viability of H9C2 cells was detected using CCK-8 assay. The apoptosis of H9C2 cells was detected by flow cytometry. The interaction between CREB and MIAT promoter regions was confirmed by dual-luciferase reporter gene assay and ChIP assay.ResultsIn MI/R rats, catechin improved heart function and down-regulated lncRNA MIAT expression in myocardial tissue. In H/R-induced H9C2 cells, catechin protected against cell apoptosis, and lncRNA MIAT overexpression attenuated this protective effect of catechin. We confirmed that transcription factor CREB could bind to MIAT promoter region, and catechin suppressed lncRNA MIAT expression through up-regulating CREB. Catechin improved mitochondrial function and relieved apoptosis through promoting Akt/Gsk-3β activation. In addition, MIAT inhibited Akt/Gsk-3β activation and promoted cell apoptosis in H/R-induced H9C2 cells. Finally, we found catechin promoted Akt/Gsk-3β activation through inhibiting MIAT expression in H/R-induced H9C2 cells.ConclusionCatechin relieved H/R-induced myocardial cell apoptosis through regulating CREB/lncRNA MIAT/Akt/Gsk-3β pathway.
| S-EPMC7011153 | biostudies-literature
Project description:A nested PCR for genus-specific amplification of the Chlamydia omp1 locus was established. This PCR detected single template molecules in 200-microl specimen aliquots. Amplified chlamydial omp1 alleles were typed by heminested species PCRs and allele PCRs. We applied this method to 407 specimens from several host animals with various clinical conditions, and we detected prevalences of chlamydiae from 6 to 50%. Amplicons from peacock enteritis and equine infertility specimens were not typeable according to present omp1 allelic criteria for the chlamydial species. DNA sequencing revealed novel omp1 alleles which were 29.9 and 47.6% divergent in the deduced peptide sequences from the most closely related chlamydiae. Phylogenetic reconstruction indicated segregation of these alleles from the current four chlamydial species (90 and 97% bootstrap support), thus strongly suggesting the existence of additional chlamydial species. Allele typing of amplicons from swine with intestinal, urogenital, and respiratory infections demonstrated several unique omp1 allelic variants of Chlamydia trachomatis. These novel alleles had deduced peptide sequences which were 11.6 to 19% divergent from porcine C. trachomatis S45. Mutations were clustered in the C-terminal region of variable segment IV of the omp1 locus encoding subspecies and serovar determinants of the chlamydial major outer membrane protein, thus implying that there are numerous serovars of porcine C. trachomatis. These results demonstrate the need for routine application of sensitive genus-specific detection of chlamydiae in animal specimens and suggest a more prominent role than anticipated for chlamydiae in animal diseases.
| S-EPMC229852 | biostudies-other
Project description:Mitochondria are critical cellular organelles that perform a wide variety of functions, including energy production and immune regulation. To perform these functions, mitochondria contain approximately 1,500 proteins, the majority of which are encoded in the nuclear genome, translated in the cytoplasm, and translocated to the mitochondria using distinct mitochondrial targeting sequences (MTS). Bacterial proteins can also contain MTS and localize to the mitochondria. For the obligate intracellular human pathogen Chlamydia trachomatis, interaction with various host cell organelles promotes intracellular replication. However, the extent and mechanisms through which Chlamydia cells interact directly with mitochondria remain unclear. We investigated the presence of MTS in the C. trachomatis genome and discovered 30 genes encoding proteins with around 70% or greater probability of mitochondrial localization. Five are translocated to the mitochondria upon ectopic expression in HeLa cells. Mass spectrometry of isolated mitochondria from infected cells revealed that two of these proteins localize to the mitochondria during infection. Comparison of mitochondria from infected and uninfected cells suggests that chlamydial infection affects the mitochondrial protein composition. Around 125 host proteins were significantly decreased or absent in mitochondria from infected cells. Among these were proapoptotic factors and those related to mitochondrial fission/fusion dynamics. Conversely, 82 host proteins were increased in or specific to mitochondria of infected cells, many of which act as antiapoptotic factors and upregulators of cellular metabolism. These data support the notion that C. trachomatis specifically targets host mitochondria to manipulate cell fate decisions and metabolic function to support pathogen survival and replication. IMPORTANCE Obligate intracellular bacteria have evolved multiple means to promote their intracellular survival and replication within the otherwise harsh environment of the eukaryotic cell. Nutrient acquisition and avoidance of cellular defense mechanisms are critical to an intracellular lifestyle. Mitochondria are critical organelles that produce energy in the form of ATP and regulate programmed cell death responses to invasive pathogenic microbes. Cell death prior to completion of replication would be detrimental to the pathogen. C. trachomatis produces at least two and possibly more proteins that target the mitochondria. Collectively, C. trachomatis infection modulates the mitochondrial protein composition, favoring a profile suggestive of downregulation of apoptosis.
| S-EPMC9769516 | biostudies-literature
Project description:Infections caused by Chlamydia trachomatis (Ct) and human papillomavirus (HPV) are the two main sexually transmitted infections; however, epidemiological data on Ct prevalence and Ct/HPV co-infection in Italy are scant. This study aimed at estimating the prevalence of Ct infection and Ct/HPV co-infection in young HPV-unvaccinated females with normal cytology, and placed particular attention on the possible association between Ct-DNA positivity and different HPV infecting genotypes. Five hundred 66 healthy females aged 16-26 years without cervical lesions, previously assessed for HPV infection (HPV-DNA prevalence: 18.2%), were tested for Ct-DNA. The overall prevalence of Ct was 5.8% (95% CI: 4.2-8.1), while Ct/HPV co-infection was recorded in 2.7% (95% CI: 1.6-4.3) of subjects. Compared with HPV-DNA-negative females, HPV-DNA positive subjects had significantly (P < 0.001) higher odds of being infected with Ct (odds ratio of 4.20, 95% CI: 2.01-8.71). Both Ct and Ct/HPV infections were much more prevalent in under 18-year-olds than in older women. Subjects positive for single high-risk HPV genotypes and various multiple HPV infections had higher odds of being Ct-DNA positive. Our findings confirm that HPV and Ct infections are very common among asymptomatic young Italian females. This underlines the urgent need for nationwide Ct screening programs and reinforcement of sexual health education, which would be the most important public health strategies, since no Ct vaccines are currently available.
| S-EPMC4514400 | biostudies-other
Project description:Chlamydia trachomatis is an obligate intracellular bacterial pathogen that is the most common cause of sexually transmitted bacterial infections and is the etiological agent of trachoma, the leading cause of preventable blindness. The organism infects epithelial cells of the genital tract and eyelid resulting in a damaging inflammatory response. Chlamydia trachomatis grows within a vacuole termed the inclusion, and its growth depends on numerous host factors, including lipids. Although a variety of mechanisms are involved in the acquisition of host cell cholesterol and glycosphingolipids by C.?trachomatis, none of the previously documented pathways for lipid acquisition are absolutely required for growth. Here we demonstrate that multiple components of the host high-density lipoprotein (HDL) biogenesis machinery including the lipid effluxers, ABCA1 and CLA 1, and their extracellular lipid acceptor, apoA-1, are recruited to the inclusion of C.?trachomatis-infected cells. Furthermore, the apoA-1 that accumulates within the inclusion colocalizes with pools of phosphatidylcholine. Knockdown of ABCA1, which mediates the cellular efflux of cholesterol and phospholipids to initiate the formation of HDL in the serum, prevents the growth of C.?trachomatis in infected HeLa cells. In addition, drugs that inhibit the lipid transport activities of ABCA1 and CLA 1 also inhibit the recruitment of phospholipids to the inclusion and prevent chlamydial growth.These results strongly suggest that C.?trachomatis co-opts the host cell lipid transport system involved in the formation of HDL to acquire lipids, such as phosphatidylcholine, that are necessary for growth.
| S-EPMC3443303 | biostudies-literature
Project description:The obligate intracellular pathogen Chlamydia trachomatis (Ctr) is the causative agent of the most common form of sexually transmitted disease in the United States. Genital infections with C. trachomatis can lead to inflammatory tissue damage followed by scarring and tissue remodeling during wound healing. Extensive scarring can lead to ectopic pregnancy or infertility. Classically activated macrophages (CA mϕ), with their anti-microbial effector mechanisms, are known to be involved in acute inflammatory processes during the course of infection. In contrast, alternatively activated macrophages (AA mϕ) contribute to tissue repair at sites of wound healing, and have reduced bactericidal functions. They are present during infection, and thus potentially can provide a growth niche for C. trachomatis during a course of infection. To address this question, macrophages derived from CD14-positive monocytes magnetically isolated from peripheral blood mononuclear cells (PBMC) were treated with interferon-γ or interleukin-4 to produce CA mϕ or AA mϕ, respectively. Confocal microscopy of chlamydial inclusions and quantification of infectious yields revealed better pathogen growth and development in AA mϕ than CA mϕ, which correlated with the reduced expression of indoleamine 2,3-dioxygenase, a known anti-chlamydial effector of the host. Furthermore, AA mϕ stained strongly for transferrin receptor and secreted higher amounts of anti-inflammatory interleukin-10 compared to CA mϕ, characteristics that indicate its suitability as host to C. trachomatis. CA, AA, and resting mϕ were infected with Ctr serovar L2. The data suggest that IL-10 produced by infected AA mϕ attenuated the anti-chlamydial function of CA mϕ with growth recovery observed in infected CA mϕ in the presence of infected, but not mock-infected AA mϕ. This could be related to our observation that IL-10 treatment of infected CA mϕ promoted better chlamydial growth. Thus, in addition to serving as an additional niche, AA mϕ might also serve as a means to modulate the immediate environment by attenuating the anti-chlamydial functions of nearby CA mϕ in a manner that could involve IL-10 produced by infected AA mϕ.
| S-EPMC6524708 | biostudies-literature