Sub-zero microRNA expression in the liver of the frozen hatchling painted turtle, Chrysemys picta marginata

Transcriptomic profiling reveals mechanism, therapeutic potential, and prognostic value of cancer stemness characteristic in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) recurrence, distant metastasis, and drug resistance remain significant obstacles in clinical prognosis. Cancer stemness is hypothesized to be a key contributor, though direct evidence is sparse. We utilized bioinformatics and machine learning techniques on single-cell RNA-seq and bulk transcriptomic datasets, complemented by basic experiments, to investigate stemness-based characteristics in NPC. Our analysis identified two potential developmental trajectories of nasopharyngeal cancer cells, each exhibiting varying levels of stemness. We subsequently identified and validated a cancer stemness-related signature (STEM-signature). Single-cell profiling revealed enrichment of LAYN + CD8 + , CTLA4 + CD4 + , CXCL13 + CD4 + T cells, tumor-associated macrophages, and CD14 + monocytes in NPC patients with high stemness. NicheNet analysis suggested these immune cells regulate cancer stemness. Bulk transcriptomic analysis corroborated these findings, indicating a poor therapeutic response in high-stemness NPC. We predicted 13 potential drugs and identified 13 stemness-related miRNAs for NPC with high stemness. A Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression model, based on this miRNA signature, predicted overall survival with an AUC of 0.71 and 0.72 in validation and testing sets, respectively. The miRNA-based stemness signature outperformed previous established signatures. Multivariate Cox regression analysis indicated that our prognostic signature could serve as an independent prognostic factor (p < 0.001). Basic experiments showed that miR-300, miR-361-5p, miR-1246, and miR-1290 enhanced the stemness characteristics of NPC cells, promoting proliferation, invasion, and migration. These findings suggest that these four stemness-related miRNAs could serve as therapeutic targets, potentially improving therapeutic responses by targeting stemness-related genes.

MicroRNA, Myostatin, and Metabolic Rate Depression: Skeletal Muscle Atrophy Resistance in Hibernating Myotis lucifugus

Little brown bats (Myotis lucifugus) cluster in hibernacula sites over winter, in which they use metabolic rate depression (MRD) to facilitate entrance and exit of hibernation. This study used small RNA sequencing and bioinformatic analyses to identify differentially regulated microRNAs (miRNAs) and to predict their downstream effects on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) terms in the skeletal muscle of torpid M. lucifugus as compared to euthermic controls. We observed a subset of ten miRNAs whose expression changed during hibernation, with predicted functional roles linked to cell cycle processes, downregulation of protein degradation via ubiquitin-mediated proteolysis, downregulation of signaling pathways, including MAPK, p53, mTOR, and TGFβ, and downregulation of cytoskeletal and vesicle trafficking terms. Taken together, our results indicate miRNA regulation corresponding to both widely utilized MRD survival strategies, as well as more hibernation- and tissue-specific roles in M. lucifugus, including skeletal muscle atrophy resistance via myostatin inhibition and insulin signaling suppression.

Comparative analysis of the liver transcriptome in the red-eared slider (Trachemys scripta elegans) post exposure to noise

Exposure to noise can cause non-auditory health problems and has been widely studied in mammals such as rats and rabbits. However, the non-auditory effects of noise exposure on reptiles (such as red-eared sliders) remain unclear. In this study, we determined the noise exposure-induced transcriptomic changes in the liver of red-eared slider (Trachemys scripta elegans) using Illumina Novaseq6000 sequencing technology. The transcriptome analysis identified 176 differentially expressed genes (DEGs), which were mainly enriched in lipid metabolism. KEGG analysis showed that by affecting the peroxisome proliferator activated receptor (PPAR) signaling pathway these DEGs increased lipid synthesis and decreased lipid oxidation. The Oil Red O staining results validated our data that noise exposure increased hepatic lipid deposition. Thus, noise exposure may lead to lipid accumulation and toxicity, mitochondrial damage, and accelerated oxidative stress. Our findings provide insights into the molecular process underlying non-auditory damage caused by noise exposure in T. scripta elegans.

Torpor-responsive microRNAs in the heart of the Monito del monte, Dromiciops gliroides

The marsupial Monito del monte (Dromiciops gliroides) utilizes both daily and seasonal bouts of torpor to preserve energy and prolong survival during periods of cold and unpredictable food availability. Torpor involves changes in cellular metabolism, including specific changes to gene expression that is coordinated in part, by the posttranscriptional gene silencing activity of microRNAs (miRNA). Previously, differential miRNA expression has been identified in D. gliroides liver and skeletal muscle; however, miRNAs in the heart of Monito del monte remained unstudied. In this study, the expression of 82 miRNAs was assessed in the hearts of active and torpid D. gliroides, finding that 14 were significantly differentially expressed during torpor. These 14 miRNAs were then used in bioinformatic analyses to identify Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were predicted to be most affected by these differentially expressed miRNAs. Overexpressed miRNAs were predicted to primarily regulate glycosaminoglycan biosynthesis, along with various signaling pathways such as Phosphoinositide-3-kinase/protein kinase B and transforming growth factor-β. Similarly, signaling pathways including phosphatidylinositol and Hippo were predicted to be regulated by the underexpression of miRNAs during torpor. Together, these results suggest potential molecular adaptations that protect against irreversible tissue damage and enable continued cardiac and vascular function despite hypothermia and limited organ perfusion during torpor.

Cardiac microRNA expression profile in response to estivation

Couch's spadefoot toad (Scaphiopus couchii) spends most of the year underground in a hypometabolic state known as estivation. During this time, they overcome significant dehydration and lack of food through many mechanisms including employing metabolic rate depression (MRD), increasing urea concentration, switching to lipid oxidation as the primary energy source, and decreasing their breathing and heart rate. MicroRNA (miRNA) are known to regulate translation by targeting messenger RNA (mRNA) for degradation or temporary storage, with several studies having reported that miRNA is differentially expressed during MRD, including estivation. Thus, we hypothesized that miRNA would be involved in gene regulation during estivation in S. couchii heart. Next-generation sequencing and bioinformatic analyses were used to assess changes in miRNA expression in response to two-month estivation and to predict the downstream effects of this expression. KEGG and GO analyses indicated that ribosome and cardiac muscle contraction are among the pathways predicted to be upregulated, whereas cell signaling and fatty acid metabolism were predicted to be downregulated. Together these results suggest that miRNAs contribute to the regulation of gene expression related to cardiac muscle physiology and energy metabolism during estivation.