MicroRNA-orchestrated pathophysiologic control in gut homeostasis and inflammation

The bta-miR-22-3p can alleviate LPS-induced inflammatory response in yak endometrial epithelial cells by targeting KSR2

Bovine endometritis is a common reproductive system disease in dairy cows that leads to decreased milk production and reproductive performance, causing significant economic losses for farmers. Research has shown that microRNAs (miRNAs) play a significant role in regulating the expression of biological genes and are closely related to the occurrence of inflammation, including bta-miR-22-3p. However, the specific molecular mechanisms by which miRNAs regulate bovine endometritis remain unclear. To investigate the regulatory mechanism of bta-miR-22-3p in yak endometritis, uterine tissues were collected from three healthy bos grunniens and three bos grunniens with endometritis, approximately 21 days postpartum. Various methods were employed, including real-time quantitative polymerase chain reaction (RT-qPCR), Western blot (WB), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence (IF). The results demonstrated that overexpression of bta-miR-22-3p led to a significant decrease (P < 0.05) in factors related to the mitogen-activated protein kinase (MAPK) signaling pathway and associated inflammatory factors, such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (P38), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). Furthermore, dual-luciferase assays confirmed that the kinase suppressor of the Ras 2 (KSR2) gene is a downstream target of bta-miR-22-3p. Overexpression of bta-miR-22-3p inhibited the expression of KSR2. When KSR2 was inhibited, the levels of MAPK signaling pathway-related factors and inflammation also significantly decreased (P < 0.05). Thus, bta-miR-22-3p suppresses the activation of the MAPK signaling pathway through the inhibition of KSR2, resulting in a reduction of inflammatory factors. In conclusion, this study demonstrated that bta-miR-22-3p targets the KSR2 gene to alleviate LPS (Lipopolysaccharide)-induced inflammatory damage.

MicroRNA Profiles in Intestinal Epithelial Cells in a Mouse Model of Sepsis

Sepsis is a systemic inflammatory disorder that leads to the dysfunction of multiple organs. In the intestine, the deregulation of the epithelial barrier contributes to the development of sepsis by triggering continuous exposure to harmful factors. However, sepsis-induced epigenetic changes in gene-regulation networks within intestinal epithelial cells (IECs) remain unexplored. In this study, we analyzed the expression profile of microRNAs (miRNAs) in IECs isolated from a mouse model of sepsis generated via cecal slurry injection. Among 239 miRNAs, 14 miRNAs were upregulated, and 9 miRNAs were downregulated in the IECs by sepsis. Upregulated miRNAs in IECs from septic mice, particularly miR-149-5p, miR-466q, miR-495, and miR-511-3p, were seen to exhibit complex and global effects on gene regulation networks. Interestingly, miR-511-3p has emerged as a diagnostic marker in this sepsis model due to its increase in blood in addition to IECs. As expected, mRNAs in the IECs were remarkably altered by sepsis; specifically, 2248 mRNAs were decreased, while 612 mRNAs were increased. This quantitative bias may be possibly derived, at least partly, from the direct effects of the sepsis-increased miRNAs on the comprehensive expression of mRNAs. Thus, current in silico data indicate that there are dynamic regulatory responses of miRNAs to sepsis in IECs. In addition, the miRNAs that were increased with sepsis had enriched downstream pathways including Wnt signaling, which is associated with wound healing, and FGF/FGFR signaling, which has been linked to chronic inflammation and fibrosis. These modifications in miRNA networks in IECs may lead to both pro- and anti-inflammatory effects in sepsis. The four miRNAs discovered above were shown to putatively target LOX, PTCH1, COL22A1, FOXO1, or HMGA2, via in silico analysis, which were associated with Wnt or inflammatory pathways and selected for further study. The expressions of these target genes were downregulated in sepsis IECs, possibly through posttranscriptional modifications of these miRNAs. Taken together, our study suggests that IECs display a distinctive miRNA profile which is capable of comprehensively and functionally reshaping the IEC-specific mRNA landscape in a sepsis model.

microRNA-196b alleviates lipopolysaccharide-induced inflammatory injury by targeting NRAS

Bovine endometritis is a serious hazard to husbandry, so it is necessary to know the mechanism of endometritis. In past research, we found microRNAs (miRNAs) might be regulators in inflammation, including miR-196b, but the mechanism of miR-196b in bovine endometritis was unknown. Therefore, we tended to find out what role miR-196b would play in bovine endometritis. As a result, we found miR-196b up-regulated in the endometritis tissue and the high concentration lipopolysaccharide (LPS)-stimulated bovine endometrial epithelial (BEND) cell line, but down-regulated in the low concentration. And, over-expression of miR-196b inhibited the expressions of some inflammatory factors, such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and neuroblastoma RAS (NRAS)/nuclear factor (NF)-κB pathway proteins. Furthermore, the dual-luciferase reporter assay and NRAS knockdown confirmed that miR-196b inhibited activation of the downstream pathway by directly targeting NRAS. In conclusion, we provide evidence that miR-196b alleviates LPS-induced inflammatory injury by targeting NRAS.

miR-195 Regulates Intestinal Epithelial Restitution after Wounding by altering Actin-Related Protein-2 Translation

Early gut epithelial restitution reseals superficial wounds after acute injury, but the exact mechanism underlying this rapid mucosal repair remains largely unknown. MicroRNA-195 (miR-195) is highly expressed in the gut epithelium and involved in many aspects of mucosal pathobiology. Actin-related proteins (ARPs) are key components essential for stimulation of actin polymerization and regulate cell motility. Here we reported that miR-195 modulates early intestinal epithelial restitution by altering ARP-2 expression at the translation level. MiR-195 directly interacted with the ARP-2 mRNA, and ectopically overexpressed miR-195 decreased ARP-2 protein without effect on its mRNA content. In contrast, miR-195 silencing by transfection with the anti-miR-195 increased ARP-2 protein expression. Decreased ARP-2 levels by miR-195 were associated with an inhibition of early epithelial restitution, as indicated by a decrease in cell migration over the wounded area. Elevation of cellular ARP-2 levels by transfection with its transgene restored cell migration after wounding in cells overexpressing miR-195. Polyamines were found to decrease miR-195 abundance and enhanced ARP-2 translation, thus promoting epithelial restitution after wounding. Moreover, increasing the levels of miR-195 disrupted F-actin cytoskeleton organization, which was prevented by ARP2 overexpression. These results indicate that miR-195 inhibits early epithelial restitution by decreasing ARP-2 translation and that miR-195 expression is negatively regulated by cellular polyamines.

Distinct Age-Specific miRegulome Profiling of Isolated Small and Large Intestinal Epithelial Cells in Mice

The intestinal epithelium serves as a dynamic barrier to protect the host tissue from exposure to a myriad of inflammatory stimuli in the luminal environment. Intestinal epithelial cells (IECs) encompass differentiated and specialized cell types that are equipped with regulatory genes, which allow for sensing of the luminal environment. Potential inflammatory cues can instruct IECs to undergo a diverse set of phenotypic alterations. Aging is a primary risk factor for a variety of diseases; it is now well-documented that aging itself reduces the barrier function and turnover of the intestinal epithelium, resulting in pathogen translocation and immune priming with increased systemic inflammation. In this study, we aimed to provide an effective epigenetic and regulatory outlook that examines age-associated alterations in the intestines through the profiling of microRNAs (miRNAs) on isolated mouse IECs. Our microarray analysis revealed that with aging, there is dysregulation of distinct clusters of miRNAs that was present to a greater degree in small IECs (22 miRNAs) compared to large IECs (three miRNAs). Further, miRNA-mRNA interaction network and pathway analyses indicated that aging differentially regulates key pathways between small IECs (e.g., toll-like receptor-related cascades) and large IECs (e.g., cell cycle, Notch signaling and small ubiquitin-related modifier pathway). Taken together, current findings suggest novel gene regulation pathways by epithelial miRNAs in aging within the gastrointestinal tissues.

The mitochondrial outer membrane protein SYNJ2BP interacts with the cell adhesion molecule TMIGD1 and can recruit it to mitochondria

BACKGROUND

Transmembrane and immunoglobulin domain-containing protein 1 (TMIGD1) is a recently identified cell adhesion molecule which is predominantly expressed by epithelial cells of the intestine and the kidney. Its expression is downregulated in both colon and renal cancer suggesting a tumor suppressive activity. The function of TMIGD1 at the cellular level is largely unclear. Published work suggests a protective role of TMIGD1 during oxidative stress in kidney epithelial cells, but the underlying molecular mechanisms are unknown.

RESULTS

In this study, we address the subcellular localization of TMIGD1 in renal epithelial cells and identify a cytoplasmic scaffold protein as interaction partner of TMIGD1. We find that TMIGD1 localizes to different compartments in renal epithelial cells and that this localization is regulated by cell confluency. Whereas it localizes to mitochondria in subconfluent cells it is localized at cell-cell contacts in confluent cells. We find that cell-cell contact localization is regulated by N-glycosylation and that both the extracellular and the cytoplasmic domain contribute to this localization. We identify Synaptojanin 2-binding protein (SYNJ2BP), a PDZ domain-containing cytoplasmic protein, which localizes to both mitochondria and the plasma membrane, as interaction partner of TMIGD1. The interaction of TMIGD1 and SYNJ2BP is mediated by the PDZ domain of SYNJ2BP and the C-terminal PDZ domain-binding motif of TMIGD1. We also find that SYNJ2BP can actively recruit TMIGD1 to mitochondria providing a potential mechanism for the localization of TMIGD1 at mitochondria.

CONCLUSIONS

This study describes TMIGD1 as an adhesion receptor that can localize to both mitochondria and cell-cell junctions in renal epithelial cells. It identifies SYNJ2BP as an interaction partner of TMIGD1 providing a potential mechanism underlying the localization of TMIGD1 at mitochondria. The study thus lays the basis for a better understanding of the molecular function of TMIGD1 during oxidative stress regulation.

Discovery of inflammatory bowel disease-associated miRNAs using a novel bipartite clustering approach

BACKGROUND

Multidimensional data mining from an integrated environment of different data sources is frequently performed in computational system biology. The molecular mechanism from the analysis of a complex network of gene-miRNA can aid to diagnosis and treatment of associated diseases.

METHODS

In this work, we mainly focus on finding inflammatory bowel disease (IBD) associated microRNAs (miRNAs) by biclustering the miRNA-target interactions aided by known IBD risk genes and their associated miRNAs collected from several sources. We rank different miRNAs by attributing to the dataset size and connectivity of IBD associated genes in the miRNA regulatory modules from biclusters. We search the association of some top-ranking miRNAs to IBD related diseases. We also search the network of discovered miRNAs to different diseases and evaluate the similarity of those diseases to IBD.

RESULTS

According to different literature, our results show the significance of top-ranking miRNA to IBD or related diseases. The ratio analysis supports our ranking method where the top 20 miRNA has approximately tenfold attachment to IBD genes. From disease-associated miRNA network analysis we found that 71% of different diseases attached to those miRNAs show more than 0.75 similarity scores to IBD.

CONCLUSION

We successfully identify some miRNAs related to IBD where the scoring formula and disease-associated network analysis show the significance of our method. This method can be a promising approach for isolating miRNAs for similar types of diseases.

Multiple Sclerosis: Melatonin, Orexin, and Ceramide Interact with Platelet Activation Coagulation Factors and Gut-Microbiome-Derived Butyrate in the Circadian Dysregulation of Mitochondria in Glia and Immune Cells

Recent data highlight the important roles of the gut microbiome, gut permeability, and alterations in mitochondria functioning in the pathophysiology of multiple sclerosis (MS). This article reviews such data, indicating two important aspects of alterations in the gut in the modulation of mitochondria: (1) Gut permeability increases toll-like receptor (TLR) activators, viz circulating lipopolysaccharide (LPS), and exosomal high-mobility group box (HMGB)1. LPS and HMGB1 increase inducible nitric oxide synthase and superoxide, leading to peroxynitrite-driven acidic sphingomyelinase and ceramide. Ceramide is a major driver of MS pathophysiology via its impacts on glia mitochondria functioning; (2) Gut dysbiosis lowers production of the short-chain fatty acid, butyrate. Butyrate is a significant positive regulator of mitochondrial function, as well as suppressing the levels and effects of ceramide. Ceramide acts to suppress the circadian optimizers of mitochondria functioning, viz daytime orexin and night-time melatonin. Orexin, melatonin, and butyrate increase mitochondria oxidative phosphorylation partly via the disinhibition of the pyruvate dehydrogenase complex, leading to an increase in acetyl-coenzyme A (CoA). Acetyl-CoA is a necessary co-substrate for activation of the mitochondria melatonergic pathway, allowing melatonin to optimize mitochondrial function. Data would indicate that gut-driven alterations in ceramide and mitochondrial function, particularly in glia and immune cells, underpin MS pathophysiology. Aryl hydrocarbon receptor (AhR) activators, such as stress-induced kynurenine and air pollutants, may interact with the mitochondrial melatonergic pathway via AhR-induced cytochrome P450 (CYP)1b1, which backward converts melatonin to N-acetylserotonin (NAS). The loss of mitochnodria melatonin coupled with increased NAS has implications for altered mitochondrial function in many cell types that are relevant to MS pathophysiology. NAS is increased in secondary progressive MS, indicating a role for changes in the mitochondria melatonergic pathway in the progression of MS symptomatology. This provides a framework for the integration of diverse bodies of data on MS pathophysiology, with a number of readily applicable treatment interventions, including the utilization of sodium butyrate.

MicroRNA‑195 triggers neuroinflammation in Parkinson's disease in a Rho‑associated kinase 1‑dependent manner

Parkinson's disease (PD) is a common progressive neurodegenerative disorder occurring in older individuals. Mechanistically, neuroinflammation is a central pathological change in the progression of PD. Activation of microglia is widely considered to be a major trigger for neuroinflammation. Certain microRNAs (miRs) are key factors in inhibiting or stimulating inflammation during the occurrence and development of PD, among which miR‑195 may be a potential crucial biomarker. However, the underlying pathological mechanisms remain unclear. To investigate the pathogenesis of PD, lipopolysaccharide (LPS) was used to establish an in vitro model of microglia activation in the present study. It was revealed that miR‑195 expression was decreased in LPS‑stimulated BV2 cells, suggesting a potential mechanism of action of miR‑195 on microglia activation. Furthermore, gain‑ and loss‑of‑function experiments were performed by successful transfection of microglia with miR‑195 mimics or inhibitors. The results demonstrated that miR‑195 overexpression inhibited the release of pro‑inflammatory cytokines, including inducible nitric oxide synthase, interleukin‑6 (IL‑6) and tumor necrosis factor‑α, but induced the release of anti‑inflammatory cytokines in LPS‑treated BV2 cells, including IL‑4 and IL‑10. In addition, Rho‑associated kinase 1 (ROCK1), which is negatively regulated by miR‑195, was increased in LPS‑stimulated BV2 cells. ROCK1 knockdown with small interfering RNA exhibited the same effect as miR‑195 overexpression on regulating microglia status, suggesting that the miR‑195/ROCK1 interaction serves a central role in inducing microglia activation. Furthermore, inhibition of ROCK1 impaired cell viability and proliferation but induced cell apoptosis in LPS‑treated miR‑195‑deficient BV2 cells. The present results suggest that miR‑195 is a potential therapeutic target for PD.

miR-222 represses expression of zipcode binding protein-1 and phospholipase C-γ1 in intestinal epithelial cells

Both zipcode binding protein-1 (ZBP1) and phospholipase C-γ1 (PLCγ1) are intimately involved in many aspects of early intestinal mucosal repair after acute injury, but the exact mechanisms that control their cellular abundances remain largely unknown. The present study shows that microRNA-222 (miR-222) interacts with the mRNAs encoding ZBP1 and PLCγ1 and regulates ZBP1 and PLCγ1 expression in intestinal epithelial cells (IECs). The biotinylated miR-222 bound specifically to the ZBP1 and PLCγ1 mRNAs in IECs. Ectopically expressed miR-222 precursor destabilized the ZBP1 and PLCγ1 mRNAs and consequently lowered the levels of cellular ZBP1 and PLCγ1 proteins. Conversely, decreasing the levels of cellular miR-222 by transfection with its antagonism increased the stability of the ZBP1 and PLCγ1 mRNAs and increased the levels of ZBP1 and PLCγ1 proteins. Overexpression of miR-222 also inhibited cell migration over the wounded area, which was partially abolished by overexpressing ZBP1 and PLCγ1. Furthermore, prevention of the increased levels of ZBP1 and PLCγ1 in the miR-222-silenced cells by transfection with specific small interfering RNAs targeting ZBP1 or PLCγ1 mRNA inhibited cell migration after wounding. These findings indicate that induced miR-222 represses expression of ZBP1 and PLCγ1 at the posttranscriptional level, thus inhibiting IEC migration during intestinal epithelial restitution after wounding.

MicroRNA in gastrointestinal cell signalling

Our gut forms an important organ and its formation, functioning and homeostasis are maintained by several factors including cell signalling pathways and commensal microflora. These factors affect pathological, physiological and immunological parameters to maintain gut health and prevent its inflammation. Among these, different intracellular signalling pathways play an important role in regulating gut homeostasis. These pathways are in turn regulated by various microRNAs that play a key role in maintaining the balance between tolerance and inflammation. This review highlights the importance of various cell signalling pathways in modulating gut homeostasis and the role specific miRNAs play in their regulation.