Identifying transcript 5' capped ends in Plasmodium falciparum

Background

The genome of the human malaria parasite Plasmodium falciparum is poorly annotated, in particular, the 5' capped ends of its mRNA transcripts. New approaches are needed to fully catalog P. falciparum transcripts for understanding gene function and regulation in this organism.

Methods

We developed a transcriptomic method based on next-generation sequencing of complementary DNA (cDNA) enriched for full-length fragments using eIF4E, a 5' cap-binding protein, and an unenriched control. DNA sequencing adapter was added after enrichment of full-length cDNA using two different ligation protocols. From the mapped sequence reads, enrichment scores were calculated for all transcribed nucleotides and used to calculate P-values of 5' capped nucleotide enrichment. Sensitivity and accuracy were increased by combining P-values from replicate experiments. Data were obtained for P. falciparum ring, trophozoite and schizont stages of intra-erythrocytic development.

Results

5' capped nucleotide signals were mapped to 17,961 non-overlapping P. falciparum genomic intervals. Analysis of the dominant 5' capped nucleotide in these genomic intervals revealed the presence of two groups with distinctive epigenetic features and sequence patterns. A total of 4,512 transcripts were annotated as 5' capped based on the correspondence of 5' end with 5' capped nucleotide annotated from full-length cDNA data.

Discussion

The presence of two groups of 5' capped nucleotides suggests that alternative mechanisms may exist for producing 5' capped transcript ends in P. falciparum. The 5' capped transcripts that are antisense, outside of, or partially overlapping coding regions may be important regulators of gene function in P. falciparum.

Analysis of complete genomes of Mycobacterium tuberculosis sublineage 2.1 (Proto-Beijing) revealed the presence of three pe_pgrs3-pe_pgrs4-like genes

Mycobacterium tuberculosis Complex (MTBC), the etiological agent of tuberculosis (TB), demonstrates considerable genotypic diversity with distinct geographic distributions and variable virulence profiles. The pe-ppe gene family is especially noteworthy for its extensive variability and roles in host immune response modulation and virulence enhancement. We sequenced an Mtb genotype L2.1 isolate from Chiangrai, Northern Thailand, using second and third-generation sequencing technologies. Comparative genomic analysis with two additional L2.1 isolates and two L2.2.AA3 (Asia Ancestral 3 Beijing) isolates revealed significant pe-ppe gene variations. Notably, all L2.1 isolates harbored three copies of pe_pgrs3-pe_pgrs4-like genes (pe_pgrs3*, pe_pgrs4*, and pe_pgrs4), different from L2.2.AA3 and H37Rv strains. Additionally, ppe53 was duplicated in all but H37Rv, and ppe50 was deleted in L2.1 isolates, contrasting with an extended ppe50 in an L2.2 isolate (Mtb 18b), which contains an additional SVP motif. Complete deletion of ppe66 and loss of wag22 were observed in L2.1 isolates. These findings highlight the high structural variability of the pe-ppe gene family, emphasizing its complex roles in Mtb-host immune interactions. This genetic complexity offers potentially critical insights into mycobacterial pathogenesis, with significant implications for vaccine development and diagnostics.

One-year mortality of tuberculosis patients on isoniazid-based treatment and its association with rapid acetylator NAT2 genotypes

BACKGROUND

NAT2 polymorphisms affect isoniazid metabolism, but their effect on mortality among individuals with tuberculosis (TB) remains unclear.

METHODS

This study used data from two TB cohorts (2005-2011, 2014-2020) and death certificate records in Thailand. Newly diagnosed Thai individuals treated with isoniazid-containing regimens were included. NAT2 genotypes-rapid, intermediate, and slow acetylator (RA, IA, SA)-were classified via haplotype inference. The primary outcome was 1-year all-cause mortality, while secondary outcomes included TB-related mortality, TB+respiratory disease-related mortality recorded in the vital registration system, and death as a TB treatment outcome. Adjusted hazard ratios (aHRs) relative to the IA type were estimated using stratified Cox proportional hazards models. Subgroup analyses targeted individuals with isoniazid-resistant TB and HIV infection.

RESULTS

A total of 1,065 individuals (766 males; mean age=51 years) were analyzed. Individuals with RA had a 1.70-fold greater all-cause mortality risk (95 % CI: 1.03-2.80) than IA. The aHRs for RA were 1.14 (0.43-3.03) for TB-related mortality, 1.59 (0.80-3.18) for TB+respiratory disease-related mortality, and 1.26 (0.67-2.37) for TB treatment outcome death. Among individuals with isoniazid-resistant TB, those with RA had a 4.68-fold (1.14-19.12) greater aHR for all-cause mortality.

CONCLUSION

The RA type is associated with increased 1-year all-cause mortality.

Association of genetic variation on X chromosome with systemic lupus erythematosus in both Thai and Chinese populations

OBJECTIVES

X chromosome has been considered as a risk factor for SLE, which is a prototype of autoimmune diseases with a significant sex difference (female:male ratio is around 9:1). Our study aimed at exploring the association of genetic variants in X chromosome and investigating the influence of trisomy X in the development of SLE.

METHODS

X chromosome-wide association studies were conducted using data from both Thai (835 patients with SLE and 2995 controls) and Chinese populations (1604 patients with SLE and 3324 controls). Association analyses were performed separately in females and males, followed by a meta-analysis of the sex-specific results. In addition, the dosage of X chromosome in females with SLE were also examined.

RESULTS

Our analyses replicated the association of TMEM187-IRAK1-MECP2, TLR7, PRPS2 and GPR173 loci with SLE. We also identified two loci suggestively associated with SLE. In addition, making use of the difference in linkage disequilibrium between Thai and Chinese populations, a synonymous variant in TMEM187 was prioritised as a likely causal variant. This variant located in an active enhancer of immune-related cells, with the risk allele associated with decreased expression level of TMEM187. More importantly, we identified trisomy X (47,XXX) in 5 of 2231 (0.22%) females with SLE. The frequency is significantly higher than that found in the female controls (0.08%; two-sided exact binomial test P=0.002).

CONCLUSION

Our study confirmed previous SLE associations in X chromosome, and identified two loci suggestively associated with SLE. More importantly, our study indicated a higher risk of SLE for females with trisomy X.

Unraveling the intricate molecular landscape and potential biomarkers in lung adenocarcinoma through integrative epigenomic and transcriptomic profiling

Lung adenocarcinoma (LUAD) remains a leading cause of cancer-related mortalities, characterized by substantial genetic heterogeneity that challenges a comprehensive understanding of its progression. This study employs next-generation sequencing data analysis to transform our comprehension of LUAD pathogenesis. Integrating epigenetic and transcriptomic data of LUAD patients, this approach assessed the critical regulatory occurrences, identified therapeutic targets, and offered profound insights into cancer molecular foundations. We employed the DNA methylation data to identify differentially methylated CpG sites and explored the transcriptome profiles of their adjacent genes. An intersectional analysis of gene expression profiles uncovered 419 differentially expressed genes (DEGs) influenced by smoke-induced differential DNA methylation, among which hub genes, including mitochondrial ribosomal proteins (MRPs), and ribosomal proteins (RPs) such as MRPS15, MRPS5, MRPL33, RPL24, RPL7L1, MRPL15, TUFM, MRPL22, and RSL1D1, were identified using a network-based approach. These hub genes were overexpressed and enriched to RNA processing, ribosome biogenesis, and mitochondrial translation, which is critical in LUAD progression. Enhancer Linking Methylation/Expression Relationship (ELMER) analysis revealed transcription factor (TF) binding motifs, such as JUN, NKX23, FOSB, RUNX3, and FOSL1, which regulated these hub genes through methylation-dependent enhancer dynamics. Predominant hypomethylation of MRPs and RPs disrupted mitochondrial function, contributed to oxidative phosphorylation (OXPHOS) and metabolic reprogramming, favoring cancer cell survival. The survival analysis validated the clinical relevance of these hub genes, with high-expression cohorts exhibiting poor overall survival (OS) outcomes enlightened their relevance in LUAD pathogenesis and presented the potential for developing novel targeted therapeutic strategies.