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RNAi in the Rhizarian Phytopathogen Plasmodiophora brassicae: The Causal Agent of Clubroot Disease in Cruciferous Crops.

Although RNA interference (RNAi) is widespread and functionally important across eukaryotes, RNAi pathways are diverse or even lost in some lineages. Rhizaria represents a major and distinct eukaryotic supergroup that includes Plasmodiophora brassicae (Pb), the causal agent of cruciferous clubroot disease, yet RNAi in this lineage remains poorly understood. Here, we characterized an unusual RNAi pathway in Pb. Small RNA sequencing across five representative Pb life stages revealed abundant siRNAs and miRNAs characterized by a predominant 21-nt length, phased genomic distribution, 2-nt 3' overhangs, and a strong 5'-cytidine bias. Three Pb miRNAs were further validated by northern blotting and stem-loop RT-qPCR. Genome analysis identified two canonical AGO homologs, PbAGO1 and PbAGO2, but no Dicer homologs, except for an RNase III-containing Drosha-like protein, PbDRL. Functional analyses showed that PbAGO1 and PbAGO2 mediate gene silencing, whereas PbDRL is required for sRNA biogenesis. Further, the cell wall component chitin was identified from Pb zoosporangia during the early infection and RNAi interfering with its biosynthesis in transgenic plants of Arabidopsis and Brassica napus blocked Pb early infection and conferred broad-spectrum resistance. Our study uncovers an unusual RNAi pathway in Rhizaria and provides a promising strategy to control cruciferous clubroot disease.

Plasmodiophora brassicae

How elephant host proteins fight-or fail-against EEHV: Insights from a multi-contrast proteomic enrichment study.

Elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV-HD) is a rapidly fatal syndrome of juvenile Asian elephants, but the host-response programs distinguishing progression from survival and the underlying pathophysiology remain poorly defined. The serum proteome of 62 Asian elephants (Elephas maximus) was profiled using a multi-contrast design stratified by age, clinical status, and infection history; protein abundance was analyzed by empirical Bayes linear modeling and Gene Ontology enrichment with semantic similarity reduction. Clinically affected elephants showed enrichment of inflammatory and stress-associated processes-including cytokine signaling and chromatin remodeling-with suppression of type I interferon signaling and homeostatic functions, whereas asymptomatic exposed elephants showed enrichment of metabolic pathways, including fatty acid and pyruvate metabolism, vesicle-mediated transport, and protein quality control. Disease-versus-exposure comparisons distinguished a progression program (inflammatory escalation with loss of proteostasis and cell adhesion) from a resilience program (preserved metabolic and cellular homeostasis); juvenile susceptibility was further associated with impaired lipid and calcium regulation and disrupted intracellular transport. Collectively, these patterns support a pathology-centered model in which fatal EEHV-HD reflects endothelial injury coupled with maladaptive inflammation and metabolic failure. Protein-level interpretation identified candidate drivers of inflammatory amplification, endothelial barrier disruption, coagulation imbalance, and resilience-including JAK1, IL1RL2, IFI44, KCNJ15, MSN, HECW2, ITPR3, MFN2, AKT1, BMPER, and DROSHA-providing a mechanistic bridge between serum proteomic changes and the vascular lesions, thrombocytopenia, DIC-like coagulopathy, edema, and hemorrhage of EEHV-HD. These findings nominate candidate proteomic signatures for future diagnostic and risk-stratification studies; longitudinal individual-level validation is required before clinical application. Because diagnostic screening identified all PCR-positive sick cases as EEHV1A and pooled group-level serum profiles were analyzed, these signatures should be interpreted as exploratory host-response programs specifically reflecting acute EEHV1A disease requiring individual-level validation.

Animals

Invertebrate miRNA pva-small RNA-11881/pva-miR-11881 as a potential RNA-based therapeutic against white spot syndrome virus in infected shrimp.

Small RNAs and microRNAs (miRNAs) play diverse roles in host virus interactions and hold promise for therapeutic applications. An uncharacterized shrimp miRNA with potent activity against white spot syndrome virus (WSSV), a major double-stranded DNA pathogen in aquaculture, was identified and characterized. Among the 1,239 differentially expressed unannotated small RNAs in Penaeus vannamei hemocytes, one of the most strongly downregulated candidates, termed pva-small RNA-11881 or pva-miR-11881, was predicted to target multiple WSSV genes. A pva-small RNA-11881/pva-miR-11881 isomir that originates from the 5' untranslated region of a host lipase 3-like gene was identified. Its primary transcript contains Drosha and Dicer processing sites, and the precursor exhibits canonical pre-miRNA features. In vivo administration of its primary transcript, pva-pri-miR-11881, significantly reduced WSSV copy number and improved shrimp survival. Mechanistically, pva-miR-11881 directly suppresses crucial WSSV genes WSSV004, WSSV164, and WSSV419 and modulates the host immune response against WSSV infection by enhancing phenoloxidase activity, thereby reducing apoptosis and necrosis, and promoting caspase-1-mediated cell death. These findings reveal that the pva-miR-11881 in P. vannamei holds strong potential as a biotherapeutic agent for managing viral diseases in shrimp.

Animals

Whole-Exome Sequencing Identifies Candidate Genomic Features Associated with Response to Platinum-Based Chemotherapy and Ixabepilone-Based Treatment in Ovarian Cancer.

Carboplatin/paclitaxel (CP) chemotherapy is the cornerstone of therapy for advanced stage ovarian cancer (OC). However, despite initial sensitivity, this regimen cannot avoid the emergence of resistance. Ixabepilone &#xb1; bevacizumab (IB) is a combination recently added to NCCN guidelines for the treatment of platinum-resistant OC. It would be desirable to identify biomarkers able to differentiate patients who are resistant to CP and IB, and biomarkers that identify which patients may benefit from IB treatment. We analyzed whole-exome-sequencing (WES) data from 49 OC patients exposed to CP, including 28 platinum-sensitive vs. 21 platinum-resistant, and 31 additional platinum-resistant patients, including 16 responders (i.e., CR/PR) vs. 15 non-responders (SD/PD) to ixabepilone &#xb1; bevacizumab. Comprehensive genetic analyses were performed to identify alterations correlated with resistance to CP and IB. WES analysis of CP responders vs. non-responders revealed differences in HRD-signatures (p < 0.05), OS (p < 0.005) and gain/loss-of-function in multiple genes associated with tumor growth/progression including but not limited to ACVR2A, INHBA, MAP3K7, ATG5, SGK1, FYN, RSPO3, NOD1 and LRRK2. WES analysis of platinum-resistant IB-treated patients revealed additional nominally significant genes and deranged pathways including gains in the DROSHA and SDHA genes in responders vs. non-responders (p < 0.05). Patients harboring HRD-signatures showed significantly higher sensitivity to CP and prolonged survival compared to HRD-negative patients. Alterations in genes associated with tumor growth/progression correlated with resistance to CP regimen and may represent novel "druggable" candidate biomarkers for the targeted treatment of CP/IB-resistant patients. Further validation in independent cohorts and preclinical experiments in CP/IB-resistant models are warranted to establish the clinical utility of these findings.

Humans

RNase III cleavage sites spread across splice junctions enforce sequential snoRNA processing.

Small nucleolar RNAs (snoRNAs) are a class of eukaryotic non-coding RNA molecules whose precursor transcripts are capped and polyadenylated. However, these end modifications are detrimental to snoRNA function and must be removed, a process typically involving excision from introns and/or endonucleolytic cleavage. For RNA precursors that host multiple snoRNAs, the sequence of maturation events is potentially important, but not well understood. Here, we report a new mode of maturation concerning snoRNA pairs that are co-hosted in the intron and the adjacent 3' exon of a precursor transcript. For a snoRNA pair with this arrangement in Schizosaccharomyces pombe, we found that the sequence surrounding an exon-exon junction within their precursor transcript folds into a hairpin after splicing of the intron. This hairpin recruits the RNase III ortholog Pac1, which participates in the maturation of the downstream snoRNA by cleaving the precursor. Our findings suggest that conditional RNase III cleavage signals hidden in an exon-exon junction evolved to enforce sequential snoRNA processing. Sequence analysis suggests that this mechanism is conserved in animals and plants.

RNA, Small Nucleolar