Increased ANKRD1 Levels in Early Senescence Mediated by RBMS1-Elicited ANKRD1 mRNA Stabilization.

Cellular senescence is a dynamic biological process triggered by sublethal cell damage and driven by specific changes in gene expression programs. We recently identified ANKRD1 (ankyrin repeat domain 1) as a protein strongly elevated after triggering senescence in fibroblasts. Here, we set out to investigate the mechanisms driving the elevated production of ANKRD1 in the early stages of senescence. Our results indicated that the rise in ANKRD1 levels after triggering senescence using etoposide (Eto) was the result of moderate increases in transcription and translation, and robust mRNA stabilization. Antisense oligomer (ASO) pulldown followed by mass spectrometry revealed a specific interaction of the RNA-binding protein RBMS1 with ANKRD1 mRNA that was confirmed by ribonucleoprotein immunoprecipitation analysis. RBMS1 abundance decreased in the nucleus and increased in the cytoplasm during Eto-induced senescence; in agreement with the hypothesis that RBMS1 may participate in post-transcriptional stabilization of ANKRD1 mRNA, silencing RBMS1 reduced, while overexpressing RBMS1 enhanced ANKRD1 mRNA half-life after Eto treatment. A segment proximal to the ANKRD1 coding region was identified as binding RBMS1 and conferring RBMS1-dependent increased expression of a heterologous reporter. We propose that RBMS1 increases expression of ANKRD1 during the early stages of senescence by stabilizing ANKRD1 mRNA.

Retinoic acid modulation of granule cell activity and spatial discrimination in the adult hippocampus.

Retinoic acid (RA), derived from vitamin A (retinol), plays a crucial role in modulating neuroplasticity within the adult brain. Perturbations in RA signaling have been associated with memory impairments, underscoring the necessity to elucidate RA's influence on neuronal activity, particularly within the hippocampus. In this study, we investigated the cell type and sub-regional distribution of RA-responsive granule cells (GCs) in the mouse hippocampus and delineated their properties. We discovered that RA-responsive GCs tend to exhibit a muted response to environmental novelty, typically remaining inactive. Interestingly, chronic dietary depletion of RA leads to an abnormal increase in GC activation evoked by a novel environment, an effect that is replicated by the localized application of an RA receptor beta (RARß) antagonist. Furthermore, our study shows that prolonged RA deficiency impairs spatial discrimination-a cognitive function reliant on the hippocampus-with such impairments being reversible with RA replenishment. In summary, our findings significantly contribute to a better understanding of RA's role in regulating adult hippocampal neuroplasticity and cognitive functions.

Increased PTCHD4 expression via m6A modification of PTCHD4 mRNA promotes senescent cell survival.

RNA modifications, including N6-methyladenosine (m6A), critically modulate protein expression programs in a range of cellular processes. Although the transcriptomes of cells undergoing senescence are strongly regulated, the landscape and impact of m6A modifications during senescence are poorly understood. Here, we report a robust m6A modification of PTCHD4 mRNA, encoding Patched Domain-Containing Protein 4, in senescent cells. The METTL3/METTL14 complex was found to incorporate the m6A modification on PTCHD4 mRNA; addition of m6A rendered PTCHD4 mRNA more stable and increased PTCHD4 production. MeRIP RT-qPCR and eCLIP analyses were used to map this m6A modification to the last exon of PTCHD4 mRNA. Further investigation identified IGF2BP1, but not other m6A readers, as responsible for the stabilization and increased abundance of m6A-modified PTCHD4 mRNA. Silencing PTCHD4, a transmembrane protein, enhanced growth arrest and DNA damage in pre-senescent cells and sensitized them to senolysis and apoptosis. Our results indicate that m6A modification of PTCHD4 mRNA increases the production of PTCHD4, a protein associated with senescent cell survival, supporting the notion that regulating m6A modification on specific mRNAs could be exploited to eliminate senescent cells for therapeutic benefit.

Surfaceome analysis of extracellular vesicles from senescent cells uncovers uptake repressor DPP4.

Senescent cells are beneficial for repairing acute tissue damage, but they are harmful when they accumulate in tissues, as occurs with advancing age. Senescence-associated extracellular vesicles (S-EVs) can mediate cell-to-cell communication and export intracellular content to the microenvironment of aging tissues. Here, we studied the uptake of EVs from senescent cells (S-EVs) and proliferating cells (P-EVs) and found that P-EVs were readily taken up by proliferating cells (fibroblasts and cervical cancer cells) while S-EVs were not. We thus investigated the surface proteome (surfaceome) of P-EVs relative to S-EVs derived from cells that had reached senescence via replicative exhaustion, exposure to ionizing radiation, or treatment with etoposide. We found that relative to P-EVs, S-EVs from all senescence models were enriched in proteins DPP4, ANXA1, ANXA6, S10AB, AT1A1, and EPHB2. Among them, DPP4 was found to selectively prevent uptake by proliferating cells, as ectopic overexpression of DPP4 in HeLa cells rendered DPP4-expressing EVs that were no longer taken up by other proliferating cells. We propose that DPP4 on the surface of S-EVs makes these EVs refractory to internalization by proliferating cells, advancing our knowledge of the impact of senescent cells in aging-associated processes.

Two antisense RNAs-AFAP1-AS1 and MLK7-AS1-promote colorectal cancer progression by sponging miR-149-5p and miR-485-5p.

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths. Antisense RNAs (asRNAs) are closely associated with cancer malignancy. This study aimed to identify the action mechanism of asRNAs in controlling CRC malignancy. Analysis of the RNA sequencing data revealed that AFAP1-AS1 and MLK7-AS1 were upregulated in CRC patients and cell lines. High levels of both asRNAs were associated with poor prognosis in patients with CRC. Both in vitro and in vivo experiments revealed that the knockdown of the two asRNAs decreased the proliferative and metastatic abilities of CRC cells. Mechanistically, AFAP1-AS1 and MLK7-AS1 decreased the levels of miR-149-5p and miR-485-5p by functioning as ceRNAs. Overexpression of miRNAs by introducing miRNA mimics suppressed the expression of SHMT2 and IGFBP5 by directly binding to the 3' UTR of their mRNA. Knockdown of both asRNAs decreased the expression of SHMT2 and IGFBP5, which was reversed by inhibition of both miRNAs by miRNA inhibitors. In vivo pharmacological targeting of both asRNAs by small interfering RNA-loaded nanoparticles showed that knockdown of asRNAs significantly reduced tumor growth and metastasis. Our findings demonstrate that AFAP1-AS1 and MLK7-AS1 promote CRC progression by sponging the tumor-suppressing miRNAs miR-149-5p and miR-485-5p, thus upregulating SHMT2 and IGFBP5.

Toxicity and Biodistribution of Fragmented Polypropylene Microplastics in ICR Mice.

Currently, polypropylene (PP) is used in various products, thus leading to high daily exposure in humans. Thus, it is necessary to evaluate the toxicological effects, biodistribution, and accumulation of PP microplastics in the human body. In this study, administration of two particle sizes of PP microplastics (approximately 5 and 10-50 µm) did not lead to any significant changes in several toxicological evaluation parameters, including body weight and pathological examination, compared with the control group in ICR mice. Therefore, the approximate lethal dose and no-observed-adverse-effect level of PP microplastics in ICR mice were established as ≥2000 mg/kg. Furthermore, we manufactured cyanine 5.5 carboxylic acid (Cy5.5-COOH)-labeled fragmented PP microplastics to monitor real-time in vivo biodistribution. After oral administration of the Cy5.5-COOH-labeled microplastics to the mice, most of the PP microplastics were detected in the gastrointestinal tract and observed to be out of the body after 24 h in IVIS Spectrum CT. Therefore, this study provides a new insight into the short-term toxicity, distribution, and accumulation of PP microplastics in mammals.

Pleiotropic effects of BAFF on the senescence-associated secretome and growth arrest.

Senescent cells release a variety of cytokines, proteases, and growth factors collectively known as the senescence-associated secretory phenotype (SASP). Sustained SASP contributes to a pattern of chronic inflammation associated with aging and implicated in many age-related diseases. Here, we investigated the expression and function of the immunomodulatory cytokine BAFF (B-cell activating factor; encoded by the TNFSF13B gene), a SASP protein, in multiple senescence models. We first characterized BAFF production across different senescence paradigms, including senescent human diploid fibroblasts (WI-38, IMR-90) and monocytic leukemia cells (THP-1), and tissues of mice induced to undergo senescence. We then identified IRF1 (interferon regulatory factor 1) as a transcription factor required for promoting TNFSF13B mRNA transcription in senescence. We discovered that suppressing BAFF production decreased the senescent phenotype of both fibroblasts and monocyte-like cells, reducing IL6 secretion and SA-ß-Gal staining. Importantly, however, the influence of BAFF on the senescence program was cell type-specific: in monocytes, BAFF promoted the early activation of NF-κB and general SASP secretion, while in fibroblasts, BAFF contributed to the production and function of TP53 (p53). We propose that BAFF is elevated across senescence models and is a potential target for senotherapy.

The Transcription Factor NRF2 Has Epigenetic Regulatory Functions Modulating HDACs, DNMTs, and miRNA Biogenesis.

The epigenetic regulation of gene expression is a complex and tightly regulated process that defines cellular identity and is associated with health and disease processes. Oxidative stress is capable of inducing epigenetic modifications. The transcription factor NRF2 (nuclear factor erythroid-derived 2-like 2) is a master regulator of cellular homeostasis, regulating genes bearing antioxidant response elements (AREs) in their promoters. Here, we report the identification of ARE sequences in the promoter regions of genes encoding several epigenetic regulatory factors, such as histone deacetylases (HDACs), DNA methyltransferases (DNMTs), and proteins involved in microRNA biogenesis. In this research, we study this possibility by integrating bioinformatic, genetic, pharmacological, and molecular approaches. We found ARE sequences in the promoter regions of genes encoding several HDACs, DNMTs, and proteins involved in miRNA biogenesis. We confirmed that NRF2 regulates the production of these genes by studying NRF2-deficient cells and cells treated with dimethyl fumarate (DMF), an inducer of the NRF2 signaling pathway. In addition, we found that NRF2 could be involved in the target RNA-dependent microRNA degradation (TDMD) of miR-155-5p through its interaction with Nfe2l2 mRNA. Our data indicate that NRF2 has an epigenetic regulatory function, complementing its traditional function and expanding the regulatory dimensions that should be considered when developing NRF2-centered therapeutic strategies.

Proteomes of primary skin fibroblasts from healthy individuals reveal altered cell responses across the life span.

Changes in the proteome of different human tissues with advancing age are poorly characterized. Here, we studied the proteins present in primary skin fibroblasts collected from 82 healthy individuals across a wide age spectrum (22-89 years old) who participated in the GESTALT (Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing) study of the National Institute on Aging, NIH. Proteins were extracted from lysed fibroblasts and subjected to liquid chromatography-mass spectrometry analysis, and the expression levels of 9341 proteins were analyzed using linear regression models. We identified key pathways associated with skin fibroblast aging, including autophagy, scavenging of reactive oxygen species (ROS), ribosome biogenesis, DNA replication, and DNA repair. Changes in these prominent pathways were corroborated using molecular and cell culture approaches. Our study establishes a framework of the global proteome governing skin fibroblast aging and points to possible biomarkers and therapeutic targets.

Application of the effective diameters of porous media to the non-Darcy flow analyses.

Non-Darcy flows are a vital event leading to the inaccuracy in flow performance evaluation, particularly in the fractured wells in shale gas and tight oil deposits. The internal flow commonly indicates high flow rates at the early period of production, owing to the large geometric size of hydraulic fracture and high porosity in proppant packs. After that, the production flow rate decays steeply until the Darcy flow regime is attained. Therefore, accurate porous flow analyses from the Darcy to Forchheimer and then turbulent flow regimes are essential for optimal facility designs and economic productions in the unconventional deposits. The Comiti capillary model is recognised as the leading non-Darcy flow correlation for simple packed beds comprising mono-size grains. However, in actual hydraulic fractures, various types of proppants are used simultaneously and generally combined with numerous soil grains of different sizes and shapes. In this study, the Comiti model is modified by incorporating the effective diameters of the porous media and then examined for mixed complex multi-size packs. Subsequently, a novel type of non-Darcy flow equation is presented according to the logarithmic turbulent friction factor based on the physical variables determined only in the Darcy flow regime. The new equation presents accurate results for all the types of proppant packs under wide porosity and permeability ranges. The generalised non-Darcy flow correlation, which can be extensively employed from the Darcy to non-Darcy flow analyses, particularly beyond the Forchheimer regime, is presented for the accurate flow evaluation of the fractured reservoirs.

Somatic uniparental disomy mitigates the most damaging EFL1 allele combination in Shwachman-Diamond syndrome.

Shwachman-Diamond syndrome (SDS; OMIM #260400) is caused by variants in SBDS (Shwachman-Bodian-Diamond syndrome gene), which encodes a protein that plays an important role in ribosome assembly. Recent reports suggest that recessive variants in EFL1 are also responsible for SDS. However, the precise genetic mechanism that leads to EFL1-induced SDS remains incompletely understood. Here we present 3 unrelated Korean SDS patients who carry biallelic pathogenic variants in EFL1 with biased allele frequencies, resulting from a bone marrow-specific somatic uniparental disomy in chromosome 15. The recombination events generated cells that were homozygous for the relatively milder variant, allowing for the evasion of catastrophic physiologic consequences. However, the milder EFL1 variant was still solely able to impair 80S ribosome assembly and induce SDS features in cell line and animal models. The loss of EFL1 resulted in a pronounced inhibition of terminal oligopyrimidine element-containing ribosomal protein transcript 80S assembly. Therefore, we propose a more accurate pathogenesis mechanism of EFL1 dysfunction that eventually leads to aberrant translational control and ribosomopathy.

hnRNPK-regulated LINC00263 promotes malignant phenotypes through miR-147a/CAPN2.

Malignant characteristics of cancers, represented by rapid cell proliferation and high metastatic potential, are a major cause of high cancer-related mortality. As a multifunctional RNA-binding protein, heterogeneous nuclear ribonucleoprotein K (hnRNPK) is closely associated with cancer progression in various types of cancers. In this study, we sought to identify hnRNPK-regulated long intergenic non-coding RNAs (lincRNAs) that play a critical role in the regulation of cancer malignancy. We found that hnRNPK controlled malignant phenotypes including invasiveness, proliferation, and clonogenicity. RNA sequencing and functional studies revealed that LINC00263, a novel target of hnRNPK, is involved in the oncogenic functions of hnRNPK. Knockdown of LINC00263 mitigated the malignant capabilities. Conversely, increased malignant phenotypes were observed in LINC00263-overexpressing cells. Since LINC00263 was mainly localized in the cytosol and highly enriched in Argonaute 2-immunoprecipitation (Ago2-IP), we hypothesized that LINC00263 acts as a competitive endogenous RNA (ceRNA), and thus sought to identify LINC00263-associated microRNAs. Using small RNA sequencing followed by antisense oligonucleotide pull-down, miR-147a was selected for further study. We found that miR-147a negatively regulates LINC00263 via direct interaction, thus suppressing malignant capabilities. Moreover, knockdown of hnRNPK and LINC00263 upregulated miR-147a, indicating that LINC00263 serves as a ceRNA for miR-147a. By analyzing RNA sequencing data and miRNA target prediction, calpain 2 (CAPN2) was identified as a putative target of miR-147a. Ago2-IP and luciferase reporter assay revealed that miR-147a suppressed CAPN2 expression by directly binding to the 3'UTR of CAPN2 mRNA. In addition, we found that the weakened malignant capabilities following knockdown of hnRNPK or LINC00263 were restored by miR-147a inhibition or CAPN2 overexpression. Furthermore, our findings were validated in various other types of cancer cells including lung cancer, colorectal cancer, neuroblastoma, and melanoma. Collectively, we demonstrate that hnRNPK-regulated LINC00263 plays an important role in cancer malignancy by acting as a miR-147a decoy and thus upregulating CAPN2.

Correction: MicroRNA-17-5p regulates EMT by targeting vimentin in colorectal cancer.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

MicroRNA-17-5p regulates EMT by targeting vimentin in colorectal cancer.

BACKGROUND: Epithelial-mesenchymal transition (EMT) is the most common cause of death in colorectal cancer (CRC). In this study, we investigated the functional roles of miRNA-17-5p in EMT of CRC cells. METHODS: In order to determine if miRNA-17-5p regulated EMT, the precursors and inhibitors of miR-17-5p were transduced into four CRC cells. To evaluate the regulatory mechanism, we performed argonaute 2 (Ago2) immunoprecipitation (IP) and luciferase assay. In addition, we used an intra-splenic injection mouse model of BALB/c nude mice to investigate the metastatic potential of miRNA-17-5p in vivo. RESULTS: The miRNA-17-5p expression was lower in primary CRC tissues with metastasis than in primary CRC tissues without metastasis in our RNA sequencing data of patient tissue. Real-time quantitative PCR revealed that miRNA-17-5p was inversely correlated with that of vimentin in five CRC cell lines. Over-expression of miRNA-17-5p decreased vimentin expression and inhibited cell migration and invasion in both LoVo and HT29 cells. However, inhibition of miRNA-17-5p showed the opposite effect. Ago2 IP and luciferase assay revealed that miRNA-17-5p directly bound to the 3'UTR of VIM mRNA. Furthermore, miRNA-17-5p inhibited the metastasis of CRC into liver in vivo. CONCLUSIONS: Our results demonstrated that miRNA-17-5p regulates vimentin expression, thereby regulating metastasis of CRC.

Hippocampal mossy cell involvement in behavioral and neurogenic responses to chronic antidepressant treatment.

Most antidepressants, including selective serotonin reuptake inhibitors (SSRIs), initiate their drug actions by rapid elevation of serotonin, but they take several weeks to achieve therapeutic onset. This therapeutic delay suggests slow adaptive changes in multiple neuronal subtypes and their neural circuits over prolonged periods of drug treatment. Mossy cells are excitatory neurons in the dentate hilus that regulate dentate gyrus activity and function. Here we show that neuronal activity of hippocampal mossy cells is enhanced by chronic, but not acute, SSRI administration. Behavioral and neurogenic effects of chronic treatment with the SSRI, fluoxetine, are abolished by mossy cell-specific knockout of p11 or Smarca3 or by an inhibition of the p11/AnxA2/SMARCA3 heterohexamer, an SSRI-inducible protein complex. Furthermore, simple chemogenetic activation of mossy cells using Gq-DREADD is sufficient to elevate the proliferation and survival of the neural stem cells. Conversely, acute chemogenetic inhibition of mossy cells using Gi-DREADD impairs behavioral and neurogenic responses to chronic administration of SSRI. The present data establish that mossy cells play a crucial role in mediating the effects of chronic antidepressant medication. Our results indicate that compounds that target mossy cell activity would be attractive candidates for the development of new antidepressant medications.

Obligatory roles of dopamine D1 receptors in the dentate gyrus in antidepressant actions of a selective serotonin reuptake inhibitor, fluoxetine.

Depression is a leading cause of disability. Current pharmacological treatment of depression is insufficient, and development of improved treatments especially for treatment-resistant depression is desired. Understanding the neurobiology of antidepressant actions may lead to development of improved therapeutic approaches. Here, we demonstrate that dopamine D1 receptors in the dentate gyrus act as a pivotal mediator of antidepressant actions in mice. Chronic administration of a selective serotonin reuptake inhibitor (SSRI), fluoxetine, increases D1 receptor expression in mature granule cells in the dentate gyrus. The increased D1 receptor signaling, in turn, contributes to the actions of chronic fluoxetine treatment, such as suppression of acute stress-evoked serotonin release, stimulation of adult neurogenesis and behavioral improvement. Importantly, under severely stressed conditions, chronic administration of a D1 receptor agonist in conjunction with fluoxetine restores the efficacy of fluoxetine actions on D1 receptor expression and behavioral responses. Thus, our results suggest that stimulation of D1 receptors in the dentate gyrus is a potential adjunctive approach to improve therapeutic efficacy of SSRI antidepressants.

Dual-strand tumor suppressor miR-193b-3p and -5p inhibit malignant phenotypes of lung cancer by suppressing their common targets.

Emerging studies suggest that microRNAs (miRNAs) play multiple roles in cancer malignancy, including proliferation and acquisition of metastatic potential. Differentially expressed miRNAs responsible for the malignancy of lung cancer were searched by miRNA microarray using a previously established brain metastatic lung cancer model. Twenty-five miRNAs were down-regulated in brain metastatic lung cancer cells. Among those, miR-193b-3p and -5p were chosen for further studies. Their function in metastatic potential and proliferation was examined using Transwell invasion, wound healing, and colony forming assays. The underlying mechanism of tumor-suppressor miR-193b-3p and -5p was explored using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR), Western blot, Argonaute 2-RNA immunoprecipitation (Ago2-RIP), and reporter assays. Both strands of miR-193b were down-regulated in brain metastatic lung cancer cells and in tissues from lung cancer patients. Overexpression of miR-193b-3p and -5p inhibited invasive and migratory activities and diminished clonogenic ability. Conversely, inhibition of miR-193b-3p or -5p increased the metastatic potential and colony forming ability. Cyclin D1 (CCND1), Ajuba LIM Protein (AJUBA), and heart development protein with EGF like domains 1 (HEG1) were identified as common target genes of miR-193b-3p and -5p. A reporter assay and an Ago2-RIP experiment showed that both miRNAs directly bind to the 3' untranslated region (3'UTR) of the target mRNA. Knockdown of target gene reduced the proliferative and metastatic potential of primary and metastatic lung cancer cells. Our results demonstrate miR-193b is a dual-strand tumor suppressor and a novel therapeutic target for lung cancer.

Regulation of PLK1 through competition between hnRNPK, miR-149-3p and miR-193b-5p.

Polo-like kinase 1 (PLK1) is a critical regulator of cell cycle progression and apoptosis. However, its regulation remains poorly understood. In the present study, we investigated the molecular mechanism underlying the post-transcriptional regulation of PLK1. We observed that heterogeneous nuclear ribonucleoprotein K (hnRNPK) and PLK1 were positively associated in several different cancers and high expression levels of them correlated with poor prognosis in patients with cancer. Knockdown of hnRNPK resulted in reduced expression of PLK1, whereas conversely, PLK1 expression was increased in hnRNPK-overexpressing cells. We found that hnRNPK regulated PLK1 expression through KH1- and KH2-dependent interactions with the 3'UTR of PLK1 mRNA. In addition, microRNA-149-3p (miR-149-3p) and miR-193b-5p suppressed PLK1 expression by targeting the 3'UTR of PLK1 mRNA. MicroRNA-elicited enrichment of PLK1 mRNA in Ago2 immunoprecipitation was altered by the presence or absence of hnRNPK. Furthermore, the deletion of the cytosine (C)-rich sequences of the 3'UTR of PLK1 mRNA abolished the decreased PLK1 expression observed via hnRNPK silencing and administration of miRNAs, a finding that suggests that hnRNPK shares this C-rich motif with miR-149-3p and miR-193b-5p. We also found that downregulation of PLK1 by either silencing hnRNPK or overexpression of miR-149-3p and miR-193b-5p decreased clonogenicity and induced apoptosis. Our findings from this study demonstrate that hnRNPK regulates PLK1 expression by competing with the PLK1-targeting miRNAs, miR-149-3p and miR-193b-5p.

SRSF3-regulated miR-132/212 controls cell migration and invasion by targeting YAP1.

Although SRSF3 (Serine/arginine-rich splicing factor 3) plays a significant role in various biological processes, many of its functions still remain unclear. More particularly, little is known about SRSF3's involvement in the regulation of miRNA. In this report, we found that invasive and migratory abilities were inhibited in SRSF3-silenced U2OS and HeLa cells. We also found that a knockdown of SRSF3 results in a decreased expression level of REST (RE1-silencing transcription factor). The silencing of REST increased the expression of primary miR-132/212 as well as their mature forms. In particular, miR-132-3p and miR-212-3p possess an identical seed sequences and a common target gene. Overexpression of miR-132-3p and miR-212-3p suppressed the expression of YAP1 (Yes-associated protein 1) by directly binding to the 3՚UTR of its mRNA. CCND1 (Cyclin D1), which acts downstream of YAP1, was downregulated in both miR-132-3p and miR-212-3p-overexpressed cells, in correlation with diminished YAP1 levels. Taken together, our results reveal that SRSF3 controls the expression of the miR-132/212 cluster through regulating REST expression, and that the REST-elicited alteration of miRNA expression is implicated in enabling the migratory and invasive abilities of cancer cells.

hnRNPK-regulated PTOV1-AS1 modulates heme oxygenase-1 expression via miR-1207-5p.

Antisense transcripts were initially identified as transcriptional noise, but have since been reported to play an important role in the quality control of miRNA functions. In this report, we tested the hypothesis that heterogeneous nuclear ribonucleoprotein K (hnRNPK) regulates miRNA function via competitive endogenous RNAs, such as pseudogenes, long non-coding RNAs, and antisense transcripts. Based on analyses of RNA sequencing data, the knockdown of hnRNPK decreased the antisense PTOV1-AS1 transcript which harbors five binding sites for miR-1207-5p. We identified heme oxygenase-1 (HO-1) mRNA as a novel target of miR-1207-5p by western blotting and Ago2 immunoprecipitation. The knockdown of hnRNPK or PTOV1-AS1 suppressed HO-1 expression by increasing the enrichment of HO-1 mRNA in miR-1207-5p-mediated miRISC. Downregulation of HO-1 by a miR-1207-5p mimic or knockdown of hnRNPK and PTOV1-AS1 inhibited the proliferation and clonogenic ability of HeLa cells. Taken together, our results demonstrate that hnRNPKregulated PTOV1-AS1 modulates HO-1 expression via miR- 1207-5p. [BMB Reports 2017; 50(4): 220-225].