Imbalance in Unc80 RNA Editing Disrupts Dynamic Neuronal Activity and Olfactory Perception.

A-to-I RNA editing, catalyzed by the ADAR protein family, significantly contributes to the diversity and adaptability of mammalian RNA signatures, aligning with developmental and physiological needs. Yet, the functions of many editing sites are still to be defined. The Unc80 gene stands out in this context due to its brain-specific expression and the evolutionary conservation of its codon-altering editing event. The precise biological functions of Unc80 and its editing, however, are still largely undefined. In this study, we first demonstrated that Unc80 editing occurs in an ADAR2-dependent manner and is exclusive to the brain. By employing the CRISPR/Cas9 system to generate Unc80 knock-in mouse models that replicate the natural editing variations, our findings revealed that mice with the "gain-of-editing" variant (Unc80G/G) exhibit heightened basal neuronal activity in critical olfactory regions, compared to the "loss-of-editing" (Unc80S/S) counterparts. Moreover, an increase in glutamate levels was observed in the olfactory bulbs of Unc80G/G mice, indicating altered neurotransmitter dynamics. Behavioral analysis of odor detection revealed distinctive responses to novel odors-both Unc80 deficient (Unc80+/-) and Unc80S/S mice demonstrated prolonged exploration times and heightened dishabituation responses. Further elucidating the olfactory connection of Unc80 editing, transcriptomic analysis of the olfactory bulb identified significant alterations in gene expression that corroborate the behavioral and physiological findings. Collectively, our research advances the understanding of Unc80's neurophysiological functions and the impact of its editing on the olfactory sensory system, shedding light on the intricate molecular underpinnings of olfactory perception and neuronal activity.

Modular scaffolding by lncRNA HOXA10-AS promotes oral cancer progression.

Recent findings have implicated long noncoding RNAs (lncRNAs) as pivotal gene regulators for diverse biological processes, despite their lack of protein-coding capabilities. Accumulating evidence suggests the significance of lncRNAs in mediating cell signaling pathways, especially those associated with tumorigenesis. Consequently, lncRNAs have emerged as novel functional regulators and indicators of cancer development and malignancy. Recent transcriptomic profiling has recognized a tumor-biased expressed lncRNA, the HOXA10-AS transcript, whose expression is associated with patient survival. Functional cell-based assays show that the HOXA10-AS transcript is essential in the regulation of oral cancer growth and metastasis. LncRNA expression is also associated with drug sensitivity. In this study, we identify that HOXA10-AS serves as a modular scaffold for TP63 mRNA processing and that such involvement regulates cancer growth. These findings provide a functional interpretation of lncRNA-mediated molecular regulation, highlighting the significance of the lncRNA transcriptome in cancer biology.

Aldosterone-producing nodules and CYP11B1 signaling correlate in primary aldosteronism.

Autonomous cortisol secretion (ACS) could be found in some patients with unilateral primary aldosteronism (uPA). However, the histopathological patterns of uPA with concurrent ACS have not been well elucidated. The adrenal gland with the adenoma from 61 uPA patients who underwent unilateral adrenalectomy were assessed by immunohistochemistry. Bioinformatics analysis, including the Cancer Genome Atlas (TCGA) and Kyoto Encyclopedia of Genes and Genomes, was applied. The prevalence of multiple aldosterone-producing nodules or micronodules (mAPN/mAPM) was 65.6% (40/61) among our uPA patients. Concurrent ACS was identified in 32% of this uPA cohort; they were associated with the interaction of larger tumor size (>1.98 cm) and mAPN/mAPM (odds ratio = 3.08, P = 0.004). Transcriptome analysis uncovered a dominant enrichment of HSD3B7 overexpression (P = 0.004) in the adenomas of the histopathologically classical adrenal uPA lesions with concomitant mAPN/mAPM, compared with those uPA adenomas without concurrent surrounding mAPN/mAPM. We identified a novel linkage of enhanced steroidogenic genes of HSD3B7 expression concurrent with the downstream higher CYP11B1 expression; further relationship was confirmed by immunohistochemical staining and validated by TCGA bioinformatics. The presence of mAPN/mAPM in uPA patients had lower rate for biochemical success after adrenalectomy (P = 0.047). In summary, two-thirds of uPA patients had concomitant mAPN/mAPM; 1/3 of uPA patients had concurrent ACS. Steroidogenic HSD3B7/CYP11B1 signaling was associated with uPA adenomas with surrounding mAPN/mAPM. Interaction of larger adenoma size with the presence of mAPN/mAPM was linked to co-existing ACS. Such uPA patients with concomitant mAPN/mAPM had lower rate of biochemical success.

Subtypes of Histopathologically Classical Aldosterone-Producing Adenomas Yield Various Transcriptomic Signaling and Outcomes.

[Figure: see text].

circRNAome Profiling in Oral Carcinoma Unveils a Novel circFLNB that Mediates Tumour Growth-Regulating Transcriptional Response.

Deep sequencing technologies have revealed the once uncharted non-coding transcriptome of circular RNAs (circRNAs). Despite the lack of protein-coding potential, these unorthodox yet highly stable RNA species are known to act as critical gene regulatory hubs, particularly in malignancies. However, their mechanistic implications in tumor outcome and translational potential have not been fully resolved. Using RNA-seq data, we profiled the circRNAomes of tumor specimens derived from oral squamous cell carcinoma (OSCC), which is a prevalently diagnosed cancer with a persistently low survival rate. We further catalogued dysregulated circRNAs in connection with tumorigenic progression. Using comprehensive bioinformatics analyses focused on co-expression maps and miRNA-interaction networks, we delineated the regulatory networks that are centered on circRNAs. Interestingly, we identified a tumor-associated, pro-tumorigenic circRNA, named circFLNB, that was implicated in maintaining several tumor-associated phenotypes in vitro and in vivo. Correspondingly, transcriptome profiling of circFLNB-knockdown cells showed alterations in tumor-related genes. Integrated in silico analyses further deciphered the circFLNB-targeted gene network. Together, our current study demarcates the OSCC-associated circRNAome, and unveils a novel circRNA circuit with functional implication in OSCC progression. These systems-based findings broaden mechanistic understanding of oral malignancies and raise new prospects for translational medicine.

ADAR1 promotes robust hypoxia signaling via distinct regulation of multiple HIF-1α-inhibiting factors.

Adenosine deaminase acting on RNA (ADAR)-catalyzed adenosine-to-inosine RNA editing is potentially dysregulated in neoplastic progression. However, how this transcriptome recoding process is functionally correlated with tumorigenesis remains largely elusive. Our analyses of RNA editome datasets identify hypoxia-related genes as A-to-I editing targets. In particular, two negative regulators of HIF-1A-the natural antisense transcript HIF1A-AS2 and the ubiquitin ligase scaffold LIMD1-are directly but differentially modulated by ADAR1. We show that HIF1A-AS2 antagonizes the expression of HIF-1A in the immediate-early phase of hypoxic challenge, likely through a convergent transcription competition in cis ADAR1 in turn suppresses transcriptional progression of the antisense gene. In contrast, ADAR1 affects LIMD1 expression post-transcriptionally, by interfering with the cytoplasmic translocation of LIMD1 mRNA and thus protein translation. This multi-tier regulation coordinated by ADAR1 promotes robust and timely accumulation of HIF-1α upon oxygen depletion and reinforces target gene induction and downstream angiogenesis. Our results pinpoint ADAR1-HIF-1α axis as a hitherto unrecognized key regulator in hypoxia.

Tumor-associated intronic editing of HNRPLL generates a novel splicing variant linked to cell proliferation.

Processing of the eukaryotic transcriptome is a dynamic regulatory mechanism that confers genetic diversity, and splicing and adenosine to inosine (A-to-I) RNA editing are well-characterized examples of such processing. Growing evidence reveals the cross-talk between the splicing and RNA editing, but there is a paucity of substantial evidence for its mechanistic details and contribution in a physiological context. Here, our findings demonstrate that tumor-associated differential RNA editing, in conjunction with splicing machinery, regulates the expression of variants of HNRPLL, a gene encoding splicing factor. We discovered an HNRPLL transcript variant containing an additional exon 12A (E12A), which is a substrate of ADAR1 and ADAR2. Adenosine deaminases acting on RNA (ADAR) direct deaminase-dependent expression of the E12A transcript, and ADAR-mediated regulation of E12A is largely splicing-based, and does not affect the stability or nucleocytoplasmic distribution of the transcript. Furthermore, ADAR-mediated modification of exon 12A generates an enhancer for the oncogenic splicing factor SRSF1 and consequently promotes the frequency of alternative splicing. Gene expression profiling by RNA-seq revealed that E12A acts distinctly from HNRPLL and regulates a set of growth-related genes, such as cyclin CCND1 and growth factor receptor TGFBR1 Accordingly, silencing E12A expression leads to impaired clonogenic ability and enhanced sensitivity to doxorubicin, thus highlighting the significance of this alternative isoform in tumor cell survival. In summary, we present the interplay of RNA editing and splicing as a regulatory mechanism of gene expression and also its physiological relevance. These findings extend our understanding of transcriptional dynamics and provide a mechanistic explanation to the link of RNA editors to tumorigenesis.

ADAR1-mediated 3' UTR editing and expression control of antiapoptosis genes fine-tunes cellular apoptosis response.

Adenosine-to-inosine RNA editing constitutes a crucial component of the cellular transcriptome and critically underpins organism survival and development. While recent high-throughput approaches have provided comprehensive documentation of the RNA editome, its functional output remains mostly unresolved, particularly for events in the non-coding regions. Gene ontology analysis of the known RNA editing targets unveiled a preponderance of genes related to apoptosis regulation, among which proto-oncogenes XIAP and MDM2 encode two the most abundantly edited transcripts. To further decode this potential functional connection, here we showed that the main RNA editor ADAR1 directly targets this 3' UTR editing of XIAP and MDM2, and further exerts a negative regulation on the expression of their protein products. This post-transcriptional silencing role was mediated via the inverted Alu elements in the 3' UTR but independent of alteration in transcript stability or miRNA targeting. Rather, we discovered that ADAR1 competes transcript occupancy with the RNA shuttling factor STAU1 to facilitate nuclear retention of the XIAP and MDM2 mRNAs. As a consequence, ADAR1 may acquire functionality in part by conferring spatial distribution and translation efficiency of the target transcripts. Finally, abrogation of ADAR1 expression or catalytic activity elicited a XIAP-dependent suppression of apoptotic response, whereas ectopic expression reversed this protective effect on cell death. Together, our results extended the known functions of ADAR1 and RNA editing to the critical fine-tuning of the intracellular apoptotic signaling and also provided mechanistic explanation for ADAR1's roles in development and tumorigenesis.