CEBPα/miR-101b-3p promotes meningoencephalitis in mice infected with Angiostrongylus cantonensis by promoting microglial pyroptosis.

BACKGROUND: Angiostrongylus cantonensis (A. cantonensis) infection can induce acute inflammation, which causes meningoencephalitis and tissue mechanical injury to the brain. Parasite infection-induced microRNAs play important roles in anti-parasite immunity in non-permissive hosts. miR-101b-3p is highly expressed after A. cantonensis infection; however, the role of miR-101b-3p and the transcription regulation of miR-101b-3p in A. cantonensis infection remain poorly characterized. RESULTS: In the present study, we found that miR-101b-3p inhibition alleviated inflammation infiltration and pyroptosis in A. cantonensis infection. In addition, we found that CCAAT/enhancer-binding protein alpha (CEBPα) directly bound to the - 6-k to - 3.5-k region upstream of miR-101b, and CEBPα activated miR-101b-3p expression in microglia. These data suggest the existence of a novel CEBPα/miR-101b-3p/pyroptosis pathway in A. cantonensis infection. Further investigation verified that CEBPα promotes pyroptosis by activating miR-101b-3p expression in microglia, and microglial pyroptosis further promoted inflammation. CONCLUSIONS: Our results suggest that a CEBPα/miR-101b-3p/pyroptosis pathway may contribute to A. cantonensis infection-induced inflammation and highlight the pro-inflammatory effect of miR-101b-3p. Video Abstract.

miR-101b Regulates Lipid Deposition and Metabolism of Primary Hepatocytes in Teleost Yellow Catfish Pelteobagrus fulvidraco.

Excessive fat deposition in the hepatocytes, associated with excess dietary fat intake, was related to the occurrence of fatty livers in fish. miR-101b plays the important roles in controlling lipid metabolism, but the underlying mechanism at the post-transcriptional level remains unclear. The purpose of this study is to explore the roles and mechanism of miR-101b-mediating lipid deposition and metabolism in yellow catfish Pelteobagrus fulvidraco. We found that miR-101b directly targeted fatty acid translocase (cd36), caspase9 (casp9) and autophagy-related gene 4A (atg4a). Furthermore, using palmitic acid (PA) or oleic acid (OA) to incubate the primary hepatocytes of yellow catfish, we demonstrated that miR-101b inversely regulated cd36, casp9, and atg4a expression at the transcriptional level; the inhibition of miR-101b aggravated fatty acids (FAs, PA or OA)-induced lipid accumulation, indicating that miR-101b mediated FAs-induced variations of lipid metabolism in yellow catfish. Taken together, our study gave novel insight into the regulatory mechanism of lipid deposition and metabolism and might provide potential targets for the prevention and treatment of fatty livers in fish.

Regulatory effect of host miR-101b-3p on parasitism of nematode Angiostrongylus cantonensis via superoxide dismutase 3.

MicroRNA plays a vital role in the regulation of host-parasite interaction. In recent years, genomic and transcriptomic resources have become increasingly available for many helminths, but only a limited number of reports in this area are on the regulatory effects of host microRNAs on parasitic nematodes. In this work, we screened increased expression of host microRNAs after nematode infection from miRNA-seq data and predicted target genes by combined bioinformatics analysis and transcriptional profiling. We elucidated regulatory effects of one host miRNA on nematode infection using miRNA inhibitor and adeno-associated virus (AAV)-based TuD miRNA inhibitor. Using AAV-based TuD miRNA inhibitor, we showed that stable blockade of mmu-miR-101b-3p could alleviate the pathological damages of Angiostrongylus cantonensis, a parasitic nematode. Data from a luciferase report assay showed that mmu-miR-101b-3p targeted the extracellular superoxide dismutase 3 (Acsod3). Increased Acsod3 expression in larvae and alleviated oxidative damages were seen in the groups receiving mmu-miR-101b-3p inhibitor treatment in vitro and AAV-based TuD miRNA inhibitor injection in vivo. Results of this study demonstrate that murine miR-101b-3p inhibits the expression of antioxidant enzyme in A. cantonensis to strengthen host oxidative responses to nematodes. This work expands our knowledge of interspecies regulation of nematode gene expression by of host miRNAs.

Targeting the HDAC2/HNF-4A/miR-101b/AMPK Pathway Rescues Tauopathy and Dendritic Abnormalities in Alzheimer's Disease.

Histone deacetylase 2 (HDAC2) plays a major role in the epigenetic regulation of gene expression. Previous studies have shown that HDAC2 expression is strongly increased in Alzheimer's disease (AD), a major neurodegenerative disorder and the most common form of dementia. Moreover, previous studies have linked HDAC2 to Aß overproduction in AD; however, its involvement in tau pathology and other memory-related functions remains unclear. Here, we show that increased HDAC2 levels strongly correlate with phosphorylated tau in a mouse model of AD. HDAC2 overexpression induced AD-like tau hyperphosphorylation and aggregation, which were accompanied by a loss of dendritic complexity and spine density. The ectopic expression of HDAC2 resulted in the deacetylation of the hepatocyte nuclear factor 4α (HNF-4A) transcription factor, which disrupted its binding to the miR-101b promoter. The suppression of miR-101b caused an upregulation of its target, AMP-activated protein kinase (AMPK). The introduction of miR-101b mimics or small interfering RNAs (siRNAs) against AMPK blocked HDAC2-induced tauopathy and dendritic impairments in vitro. Correspondingly, miR-101b mimics or AMPK siRNAs rescued tau pathology, dendritic abnormalities, and memory deficits in AD mice. Taken together, the current findings implicate the HDAC2/miR-101/AMPK pathway as a critical mediator of AD pathogenesis. These studies also highlight the importance of epigenetics in AD and provide novel therapeutic targets.

MicroRNA-101b attenuates cardiomyocyte hypertrophy by inhibiting protein kinase C epsilon signaling.

Previously, a surgical regression model identified microRNA-101b (miR-101b) as a potential inhibitor of cardiac hypertrophy. Here, we investigated the antihypertrophic mechanism of miR-101b using neonatal rat ventricular myocytes. miR-101b markedly suppressed agonist-induced cardiac hypertrophy as shown by cell size and fetal gene expression. By systems biology approaches, we identified protein kinase C epsilon (PKCε) as the major target of miR-101b. Our results from qRT-PCR, western blot, and luciferase reporter assays confirm that PKCε is a direct target of miR-101b. In addition, we found that effectors downstream of PKCε (p-AKT, p-ERK1/2, p-NFAT, and p-GSK3ß) are also affected by miR-101b. Our study reveals a novel inhibitory mechanism for miR-101b as a negative regulator of cardiac hypertrophy.

Dysregulated expression of miR-101b and miR-26b lead to age-associated increase in LPS-induced COX-2 expression in murine macrophage.

Aging is the natural process of decline in physiological structure and function of various molecules, cells, tissues, and organs. Growing evidence indicates that increased immune genetic diversity and dysfunction of immune system cause aging-related pathophysiological process with the growth of age. In the present study, we observed that LPS-induced higher activation of cyclooxygenase (COX)-2 promoter is associated with the upregulated binding activity of nuclear factor kappa B (NF-κB) in peritoneal macrophages of aged mice than young ones. Additionally, COX-2 is a direct target of miR-101b and miR-26b in the macrophages. Significant upregulation of miR-101b and miR-26b effectively prevented LPS-induced excessive expression of COX-2 in the young mice. Because these negative regulatory factors were unresponsive to LPS stimulation, the levels of COX-2 were markedly higher in the macrophages of aged mice. Further study showed that NF-κB activation contributed to the increase in the expression of miR-101b and miR-26b in the LPS-stimulated macrophages of young mice, but not aged ones. Moreover, histone deacetylase (HDAC) inhibitor trichostatin A (TSA) upregulated expression of miR-101b and miR-26b in the aged mouse macrophages only, but not the young cells. This demonstrated that HDAC suppressed the expression of miR-101b and miR-26b in the LPS-treated macrophages of aged mice and contributed to the aging process. TSA-induced increased expression of miR-101b and miR-26b could further suppress COX-2 expression. These findings provide novel evidence on the regulation of immune senescence and miR-101b and miR-26b, which might be promising targets in treating aged-related inflammatory diseases. Epigenetic regulation of the microRNAs (miRNAs) provides an important evidence for the treatment of innate inflammatory disease with HDAC inhibitors in elderly.