🧬 PubMed RNase III Daily Digest

We developed a physiologically relevant light damage model in pigmented mice and determine how Müller glial (MG) Dicer1/microRNA (miRNA) loss impacts retinal structure and function after injury. A moderate light damage paradigm (5,000 lux, 4 hours) was developed in pigmented mice carrying the RPE65 Leu450 variant. MG-specific Dicer1 conditional knockout (cKO) mice across three Cre lines (Rlbp1-CreER, Glast-CreER, Ascl1-CreER) were subjected to light damage at different developmental stages. Retinal structure and function were assessed longitudinally using optical coherence tomography (OCT), histology, and electroretinography (ERG). Preconditioning and double-damage paradigms were included as controls. The model induced progressive photoreceptor degeneration with early functional decline preceding structural loss and delayed inner retinal impairment. Across all MG-specific

Metabolic syndrome and excessive alcohol consumption (MetALD) result in liver injury and fibrosis, which are driven by increased collagen production by activated hepatic stellate cells (HSCs). Our previous studies demonstrated that LARP6, an RNA-binding protein, may facilitate collagen production. However, the expression and function of LARP6 as a regulator of fibrosis development in a disease-relevant model remain poorly understood. We demonstrated that LARP6 was upregulated in human activated HSCs in metabolic dysfunction-associated steatohepatitis (MASH) and MetALD. By using single-nucleus RNA-seq and assay for transposase-accessible chromatin sequencing, we showed that JUNB upregulated LARP6 expression in activated HSCs. Moreover, LARP6 knockdown in human HSCs suppressed fibrogenic gene expression. By integrating enhanced crosslinking and IP analysis and ribosome profiling in HSCs, we showed that LARP6 interacted with mature mRNAs comprising more than 300 genes, including RNA structural elements within COL1A1, COL1A2, and COL3A1 to regulate mRNA expression and translation. IP-mass spectrometry analysis demonstrated LARP6 protein-protein interactions with mRNA translation components and the actin cytoskeleton. Furthermore, Dicer substrate siRNA-based HSC-specific gene knockdown or pharmacological inhibition of LARP6 attenuated fibrosis development in human MASH and MetALD liver spheroids. Our results suggest LARP6 plays a key role in fibrogenic gene regulation and that targeting LARP6 in human HSCs may represent a therapeutic approach for liver fibrosis.

The rapid increase of resistance to insecticides among Anopheles mosquitoes, the primary vectors of malaria, highlights the necessity for new approaches in controlling vectors. RNA interference (RNAi) offers a targeted and environmentally safer alternative approach. Arginase in Anopheles gambiae, involved in nitrogen metabolism, presents a compelling target due to its potential role in modulating mosquito immune responses and influencing parasite development and vectorial competency. The study focused on designing and evaluating Dicer-substrate small interfering RNA (DsiRNA) molecules targeting arginase in An. gambiae to disrupt parasite development and reduce malaria transmission. DsiRNAs were designed using Integrated DNA Technologies and optimized based on GC content, secondary structure prediction, thermodynamic parameters, and off-target screening. The derived 21-mer guide strands were further evaluated through molecular docking to assess interactions with An. gambiae Ago2. To validate the docked complex for stability, a molecular dynamics (MD) simulation using 100 ns was performed, revealing stable RMSD trajectories, sustained hydrogen bonding, maintained structural compactness, and minimal residue fluctuation, indicating persistent Ago2-guide strand interactions under physiological conditions. Eight DsiRNAs demonstrated optimal biophysical and specificity profiles, among which DsiRNA6, followed by DsiRNA8, and DsiRNA1 exhibited favorable binding energy and dynamic stability. These findings highlight the structural feasibility and functional potential of selected DsiRNAs as candidates for arginase knockdown in An. gambiae and support RNAi-based strategies as promising alternatives for vector control.

Ribonuclease (RNase) III Drosha initiates microRNA (miRNA) biogenesis. Emerging evidence suggests that Drosha modulates processes beyond miRNA biogenesis, indicative of the functional complexity of Drosha. Here, we show that Drosha facilitates activation of sterol regulatory element-binding protein 1 (SREBP1), the central player in triglyceride (TG) biosynthesis, in an RNase activity-independent manner. Mechanistically, cytoplasmic Drosha interacts with Sec31, a subunit of coat protein complex II (COPII), through its arginine/serine (RS)-rich domain. This interaction promotes COPII-mediated transport and activation of SREBP1. Moreover, Akt phosphorylates Drosha at Ser237 in the RS-rich domain, which is required for the Drosha-Sec31 interaction, SREBP1 processing, and TG accumulation in response to insulin. The Akt-Drosha-SREBP1 axis was hyperactivated in mice fed a high-fat, high-sugar diet, and hepatic Drosha deletion or administration of an interfering peptide that blocked Akt-mediated phosphorylation of Drosha ameliorated liver TG deposition and insulin resistance in this mouse model. Thus, our findings uncover a noncanonical function of Drosha involved in SREBP1 processing and lipogenesis.

The levels of the microRNA-processing enzyme DICER and the hypoxia associated marker carbonic anhydrase 9 (CA9) critically influence tumor growth, aggressiveness, and response to therapy. However, their prognostic value in patients treated with definitive chemoradiotherapy (CRT) for anal squamous cell carcinoma (ASCC) remains elusive. DICER and CA9 were scored in a cohort of a total of 95 ASCC patients by multiplex immunofluorescence and next-generation sequencing for DICER on pre-treatment biopsies. They were correlated with patients' histopathological characteristics and clinical endpoints locoregional failure-free survival (LRFFS), distant metastases-free survival (DMFS), disease-free survival (DFS) and overall survival (OS). We observed a significant inverse correlation between DICER and CA9 expression. In contrast, DICER and CA9 expression did not correlate with age, gender, T/N stage, and grading. High levels of DICER protein and mRNA were prognostic for superior LRFFS (p = 0.006) and DFS (p = 0.014), while elevated levels of CA9 were associated with decreased LRFFS (p = 0.008) and decreased DFS (p = 0.023), respectively. In multivariate analyses, DICER levels remained significant for LRFFS and DFS (p = 0.020, and p = 0.033). A combined DICER high and low CA9 variable indicated a subgroup of patients most likely to respond to CRT with improved LRFFS (p = 0.002) and DFS (p = 0.006). These data indicate that elevated pretreatment levels of CA9 and low levels of DICER are correlated with an unfavorable clinical outcome in patients with ASCC treated with definitive CRT. The superior prognostic power of DICER+ CA9 suggests that DICER and hypoxia may have non-redundant roles in these malignancies.