The exercise-induced long noncoding RNA CYTOR promotes fast-twitch myogenesis in aging.

Skeletal muscle displays remarkable plasticity upon exercise and is also one of the organs most affected by aging. Despite robust evidence that aging is associated with loss of fast-twitch (type II) muscle fibers, the underlying mechanisms remain to be elucidated. Here, we identified an exercise-induced long noncoding RNA, CYTOR, whose exercise responsiveness was conserved in human and rodents. Cytor overexpression in mouse myogenic progenitor cells enhanced myogenic differentiation by promoting fast-twitch cell fate, whereas Cytor knockdown deteriorated expression of mature type II myotubes. Skeletal muscle Cytor expression was reduced upon mouse aging, and Cytor expression in young mice was required to maintain proper muscle morphology and function. In aged mice, rescuing endogenous Cytor expression using adeno-associated virus serotype 9 delivery of CRISPRa reversed the age-related decrease in type II fibers and improved muscle mass and function. In humans, CYTOR expression correlated with type II isoform expression and was decreased in aged myoblasts. Increased CYTOR expression, mediated by a causal cis­expression quantitative trait locus located within a CYTOR skeletal muscle enhancer element, was associated with improved 6-min walk performance in aged individuals from the Helsinki Birth Cohort Study. Direct CYTOR overexpression using CRISPRa in aged human donor myoblasts enhanced expression of type II myosin isoforms. Mechanistically, Cytor reduced chromatin accessibility and occupancy at binding motifs of the transcription factor Tead1 by binding, and hence sequestering, Tead1. In conclusion, the long noncoding RNA Cytor was found to be a regulator of fast-twitch myogenesis in aging.

Gene replacement therapy provides benefit in an adult mouse model of Leigh syndrome.

Mutations in nuclear-encoded mitochondrial genes are responsible for a broad spectrum of disorders among which Leigh syndrome is the most common in infancy. No effective therapies are available for this severe disease mainly because of the limited capabilities of the standard adeno-associated viral (AAV) vectors to transduce both peripheral organs and the CNS when injected systemically in adults. Here, we used the brain-penetrating AAV-PHP.B vector to reinstate gene expression in the Ndufs4 knockout mouse model of Leigh syndrome. Intravenous delivery of an AAV.PHP.B-Ndufs4 vector in 1-month-old knockout mice restored mitochondrial complex I activity in several organs including the CNS. This gene replacement strategy extended lifespan, rescued metabolic parameters, provided behavioural improvement, and corrected the pathological phenotype in the brain, retina, and heart of Ndufs4 knockout mice. These results provide a robust proof that gene therapy strategies targeting multiple organs can rescue fatal neurometabolic disorders with CNS involvement.

Clock genes-dependent acetylation of complex I sets rhythmic activity of mitochondrial OxPhos.

Physiology of living beings show circadian rhythms entrained by a central timekeeper present in the hypothalamic suprachiasmatic nuclei. Nevertheless, virtually all peripheral tissues hold autonomous molecular oscillators constituted essentially by circuits of gene expression that are organized in negative and positive feed-back loops. Accumulating evidence reveals that cell metabolism is rhythmically controlled by cell-intrinsic molecular clocks and the specific pathways involved are being elucidated. Here, we show that in vitro-synchronized cultured cells exhibit BMAL1-dependent oscillation in mitochondrial respiratory activity, which occurs irrespective of the cell type tested, the protocol of synchronization used and the carbon source in the medium. We demonstrate that the rhythmic respiratory activity is associated to oscillation in cellular NAD content and clock-genes-dependent expression of NAMPT and Sirtuins 1/3 and is traceable back to the reversible acetylation of a single subunit of the mitochondrial respiratory chain Complex I. Our findings provide evidence for a new interlocked transcriptional-enzymatic feedback loop controlling the molecular interplay between cellular bioenergetics and the molecular clockwork.

Interleukin-15 is required for immunosurveillance and immunoprevention of HER2/neu-driven mammary carcinogenesis.

INTRODUCTION: We previously demonstrated that HER2/neu-driven mammary carcinogenesis can be prevented by an interleukin-12 (IL-12)-adjuvanted allogeneic HER2/neu-expressing cell vaccine. Since IL-12 can induce the release of interleukin-15 (IL-15), in the present study we investigated the role played by IL-15 in HER2/neu driven mammary carcinogenesis and in its immunoprevention. METHODS: HER2/neu transgenic mice with homozygous knockout of IL-15 (here referred to as IL15KO/NeuT mice) were compared to IL-15 wild-type HER2/neu transgenic mice (NeuT) regarding mammary carcinogenesis, profile of peripheral blood lymphocytes and splenocytes and humoral and cellular responses induced by the vaccine. RESULTS: IL15KO/NeuT mice showed a significantly earlier mammary cancer onset than NeuT mice, with median latency times of 16 and 20 weeks respectively, suggesting a role for IL-15 in cancer immunosurveillance. Natural killer (NK) and CD8+ lymphocytes were significantly lower in IL15KO/NeuT mice compared to mice with wild-type IL-15. The IL-12-adjuvanted allogeneic HER2/neu-expressing cell vaccine was still able to delay mammary cancer onset but efficacy in IL-15-lacking mice vanished earlier: all vaccinated IL15KO/NeuT mice developed tumors within 80 weeks of age (median latency of 53 weeks), whereas more than 70 % of vaccinated NeuT mice remained tumor-free up to 80 weeks of age. Vaccinated IL15KO/NeuT mice showed less necrotic tumors with fewer CD3+ lymphocyes and lacked perforin-positive infiltrating cells compared to NeuT mice. Concerning the anti-vaccine antibody response, antibody titer was unaffected by the lack of IL-15, but less antibodies of IgM and IgG1 isotypes were found in IL15KO/NeuT mice. A lower induction by vaccine of systemic interferon-gamma (IFN-γ) and interleukin-5 (IL-5) was also observed in IL15KO/NeuT mice when compared to NeuT mice. Finally, we found a lower level of CD8+ memory cells in the peripheral blood of vaccinated IL15KO/NeuT mice compared to NeuT mice. CONCLUSIONS: We demonstrated that IL-15 has a role in mammary cancer immunosurveillance and that IL-15-regulated NK and CD8+ memory cells play a role in long-lasting immunoprevention, further supporting the potential use of IL-15 as adjuvant in immunological strategies against tumors.

Mutual antagonism between circadian protein period 2 and hepatitis C virus replication in hepatocytes.

BACKGROUND: Hepatitis C virus (HCV) infects approximately 3% of the world population and is the leading cause of liver disease, impacting hepatocyte metabolism, depending on virus genotype. Hepatic metabolic functions show rhythmic fluctuations with 24-h periodicity (circadian), driven by molecular clockworks ticking through translational-transcriptional feedback loops, operated by a set of genes, called clock genes, encoding circadian proteins. Disruption of biologic clocks is implicated in a variety of disorders including fatty liver disease, obesity and diabetes. The relation between HCV replication and the circadian clock is unknown. METHODS: We investigated the relationship between HCV core infection and viral replication and the expression of clock genes (Rev-Erbα, Rorα, ARNTL, ARNTL2, CLOCK, PER1, PER2, PER3, CRY1 and CRY2) in two cellular models, the Huh-7 cells transiently expressing the HCV core protein genotypes 1b or 3a, and the OR6 cells stably harboring the full-length hepatitis C genotype 1b replicon, and in human liver biopsies, using qRT-PCR, immunoblotting, luciferase assays and immunohistochemistry. RESULTS: In Huh-7 cells expressing the HCV core protein genotype 1b, but not 3a, and in OR6 cells, transcript and protein levels of PER2 and CRY2 were downregulated. Overexpression of PER2 led to a consistent decrease in HCV RNA replicating levels and restoration of altered expression pattern of a subset of interferon stimulated genes (ISGs) in OR6 cells. Furthermore, in liver biopsies from HCV genotype 1b infected patients, PER2 was markedly localized to the nucleus, consistent with an auto-inhibitory transcriptional feedback loop. CONCLUSIONS: HCV can modulate hepatic clock gene machinery, and the circadian protein PER2 counteracts viral replication. Further understanding of circadian regulation of HCV replication and rhythmic patterns of host-hosted relationship may improve the effectiveness of HCV antiviral therapy. This would extend to hepatic viral infections the current spectrum of chronotherapies, implemented to treat metabolic, immune related and neoplastic disease.

Interplay between SOX9, ß-catenin and PPARγ activation in colorectal cancer.

Colorectal carcinogenesis relies on loss of homeostasic mechanisms regulating cell proliferation, differentiation and survival. These cell processes have been reported to be influenced independently by transcription factors activated downstream of the Wnt pathway, such as SOX9 and ß-catenin, and by the nuclear receptor PPARγ. The purpose of this study was to explore the expression levels and functional link between SOX9, ß-catenin and PPARγ in the pathogenesis of colorectal cancer (CRC). We evaluated SOX9, ß-catenin and PPARγ expression levels on human CRC specimens by qPCR and immunoblot detection. We tested the hypothesis that PPARγ activation might affect SOX9 and ß-catenin expression using four colon cancer cell lines (CaCo2, SW480, HCT116, and HT29 cells). In CRC tissues SOX9 resulted up-regulated at both mRNA and protein levels when compared to matched normal mucosa, ß-catenin resulted up-regulated at protein levels, while PPARG mRNA and PPARγ protein levels were down-regulated. A significant relationship was observed between high PPARG and SOX9 expression levels in the tumor tissue and female gender (p=0.005 and p=0.04, respectively), and between high SOX9 expression in the tumor tissue and age (p=0.04) and microsatellite instability (MSI), in particular with MSI-H (p=0.0002). Moreover, treatment with the synthetic PPARγ ligand rosiglitazone induced different changes of SOX9 and ß-catenin expression and subcellular localization in the colon cancer cell lines examined. In conclusion, SOX9, ß-catenin and PPARγ expression levels are deregulated in the CRC tissue, and in colon cancer cell lines ligand-dependent PPARγ activation unevenly influences SOX9 and ß-catenin expression and subcellular localization, suggesting a variable mechanistic role in colon carcinogenesis.

Hepatitis delta virus induces specific DNA methylation processes in Huh-7 liver cancer cells.

Hepatitis delta virus (HDV) is a small, defective RNA virus that can infect only individuals carrying hepatitis B virus. HBV/HDV co-infection results in more severe liver disease than HBV single infection and more rapid progression to cirrhosis and hepatocellular carcinoma (HCC). The epigenetic events involved in hepatocyte transformation towards malignancy in this context are poorly known. Here we report that, in Huh-7 cells, HDV induces DNMT3b expression and is associated to E2F1 transcription factor hypermethylation. Moreover our cell cycle analysis showed that HDV induces G2/M arrest. These findings suggest that HDV could play a role in HCC development at least in part by altering DNA methylation events. A better understanding of the molecular mechanisms involved in HDV-related carcinogenesis could help to identify new therapeutic targets.

Time-Qualified Patterns of Variation of PPARγ, DNMT1, and DNMT3B Expression in Pancreatic Cancer Cell Lines.

Carcinogenesis is related to the loss of homeostatic control of cellular processes regulated by transcriptional circuits and epigenetic mechanisms. Among these, the activities of peroxisome proliferator-activated receptors (PPARs) and DNA methyltransferases (DNMTs) are crucial and intertwined. PPARγ is a key regulator of cell fate, linking nutrient sensing to transcription processes, and its expression oscillates with circadian rhythmicity. Aim of our study was to assess the periodicity of PPARγ and DNMTs in pancreatic cancer (PC). We investigated the time-related patterns of PPARG, DNMT1, and DNMT3B expression monitoring their mRNA levels by qRT-PCR at different time points over a 28-hour span in BxPC-3, CFPAC-1, PANC-1, and MIAPaCa-2 PC cells after synchronization with serum shock. PPARG and DNMT1 expression in PANC-1 cells and PPARG expression in MIAPaCa-2 cells were characterized by a 24 h period oscillation, and a borderline significant rhythm was observed for the PPARG, DNMT1, and DNMT3B expression profiles in the other cell lines. The time-qualified profiles of gene expression showed different shapes and phase relationships in the PC cell lines examined. In conclusion, PPARG and DNMTs expression is characterized by different time-qualified patterns in cell lines derived from human PC, and this heterogeneity could influence cell phenotype and human disease behaviour.

Correlations among PPARγ, DNMT1, and DNMT3B Expression Levels and Pancreatic Cancer.

Emerging evidence indicates that peroxisome proliferator-activated receptor γ (PPARγ) and DNA methyltransferases (DNMTs) play a role in carcinogenesis. In this study we aimed to evaluate the expression of PPARγ, DNMT1, and DNMT3B and their correlation with clinical-pathological features in patients with pancreatic cancer (PC), and to define the effect of PPARγ activation on DNMTs expression in PC cell lines. qRT-PCR analysis showed that DNMT3B expression was downregulated in tumors compared to normal tissues (P = 0.03), whereas PPARγ and DNMT1 levels did not show significant alterations in PC patients. Expression levels between PPARγ and DNMT1 and between DNMT1 and DNMT3B were highly correlated (P = 0.008 and P = 0.05 resp.). DNMT3B overexpression in tumor tissue was positively correlated with both lymph nodes spreading (P = 0.046) and resection margin status (P = 0.04), and a borderline association with perineural invasion (P = 0.06) was found. Furthermore, high levels of DNMT3B expression were significantly associated with a lower mortality in the whole population (HR = 0.485; 95%CI = 0.262-0.895, P = 0.02) and in the subgroup of patients without perineural invasion (HR = 0.314; 95%CI = 0.130-0.758; P = 0.01), while such association was not observed in patients with tumor invasion into perineural structures (P = 0.70). In conclusion, in vitro and in vivo PPARγ and DNMTs appear interrelated in PC, and this interaction might influence cell phenotype and disease behavior.

DNA methyltransferases 1 and 3b expression in Huh-7 cells expressing HCV core protein of different genotypes.

BACKGROUND: Hepatitis C virus infects ~3% of the population and it is a risk factor for hepatocarcinogenesis. The epigenetic mechanisms of HCV-induced hepatocyte transformation towards malignancy in this context are unclear. AIMS: The purpose of this study was to evaluate the effect of HCV core proteins of different genotypes on DNA methyltransferases (DNMTs) induction. MATERIALS/METHODS: We investigated DNMT1, DNMT3b and E-Cadherin (CDH1) mRNA and protein expression levels in an in vitro model of Huh-7 cells expressing the HCV core protein of different genotypes: 1b, 2a, 3a, 4h and 5a. RESULTS: We found that both mRNA and protein expression levels of DNMT1 and 3b were upregulated in genotype 1b HCV core expressing cells as compared to control cells. DNMT3b mRNA levels did not change in genotypes 2a, 3a, 4h and 5a, but were upregulated at the protein level by genotype 1b, 2a, 3a. CDH1 mRNA expression was downregulated only in genotype 1b, whereas its protein expression resulted in downregulation by the HCV core of genotypes 1b, 2a and 3a. Conversely, no significant changes were observed for DNMTs and CDH1 investigated in Huh-7 cells expressing the genotypes 4h and 5a. Furthermore, we present evidence that HCV core 1b protein expression induces DNMTs overexpression through STAT3 protein as demonstrated by NSC74859 treatment. Moreover, SIRT1 inhibition affected DNMT1 and 3b expression only in HCV core protein genotype 1b expressing cells as demonstrated by treatment with its inhibitor sirtinol. CONCLUSIONS: Our findings suggest that HCV core protein could play a role in HCC development at least in part by altering DNMTs expression.

Altered expression of the clock gene machinery in kidney cancer patients.

BACKGROUND AND AIM: Kidney cancer is associated with alteration in the pathways regulated by von Hippel-Lindau protein and hypoxia inducible factor α. Tight interrelationships have been evidenced between hypoxia response pathways and circadian pathways. The dysregulation of the circadian clock circuitry is involved in carcinogenesis. The aim of our study was to evaluate the clock gene machinery in kidney cancer. METHODS: mRNA expression levels of the clock genes ARNTL1, ARNTL2, CLOCK, PER1, PER2, PER3, CRY1, CRY2, TIMELESS, TIPIN and CSNK1E and of the clock controlled gene SERPINE1 were evaluated by DNA microarray assays and by qRT-PCR in primary tumor and matched nontumorous tissue collected from a cohort of 11 consecutive kidney cancer patients. RESULTS: In kidney tumor tissue, we found down-regulation of PER2 (median=0.658, Q1-Q3=0.562-0.744, P<0.01), TIMELESS (median=0.705, Q1-Q3=0.299-1.330, P=0.04) and TIPIN (median=0.556, Q1-Q3=0.385-1.945, P=0.01), up-regulation of SERPINE1 (median=1.628, Q1-Q3=0.339-4.071, P=0.04), whereas the expression of ARNTL2 (median=0.605, Q1-Q3=0.318-1.738, P=0.74) and CSNK1E (median=0.927, Q1-Q3=0.612-2.321, P=0.33) did not differ. A statistically significant correlation was evidenced between mRNA levels of PER2 and CSNKIE (r=0.791, P<0.01), PER2 and TIPIN (r=0.729, P=0.01), PER2 and SERPINE1 (r=0.704, P=0.01), TIMELESS and TIPIN (r=0.605, P=0.04), TIMELESS and CSNKIE (r=0.637, P=0.03), TIPIN and CSNKIE (r=0.940, P<0.01). CONCLUSION: In kidney cancer, the circadian clock circuitry is deregulated and the altered expression of the clock genes might be involved in disease onset and progression.

SIRT1 and the clock gene machinery in colorectal cancer.

SIRT1 and the clock genes are involved in carcinogenesis. We evaluated SIRT1 expression in 19 human colorectal cancer (CRC) specimens and clock gene expression in SIRT1-overexpressing CaCo2 and SW480 cells. In CRC, SIRT1 mean expression level was decreased. Compared to CaCo2 cells, SW480 cells displayed lower levels of SIRT1 and PER3 and higher levels of ARNTL1, CLOCK, PER1, PER2, CRY1, TIPIN, and CSNKIE. SIRT1 overexpression induced PER1 upregulation in CaCo2 and downregulation in SW480 cells. SIRT1 expression was heterogeneous in human CRC and in CRC cell lines. These results might have relevant implications for a better understanding of colorectal carcinogenesis.

ARNTL2 and SERPINE1: potential biomarkers for tumor aggressiveness in colorectal cancer.

PURPOSE: Cathepsin and plasmin may favor cancer cell invasion degrading extracellular matrix. Plasmin formation from plasminogen is regulated by plasminogen activator inhibitor type-1 (PAI-1). ARNTL2 activates the promoters of the PAI-1 gene, officially called SERPINE1, driving the circadian variation in circulating PAI-1 levels. METHODS: We evaluated ARNTL2 and SERPINE1 expression in 50 colorectal cancer specimens and adjacent normal tissue and in colon cancer cell lines. RESULTS: We found up-regulation of ARNTL2 (P = 0.004) and SERPINE1 (P = 0.002) in tumor tissue. A statistically significant association was found between high ARNTL2 mRNA levels and vascular invasion (P < 0.0001), and between high SERPINE1 mRNA levels and microsatellite instability (MSI-H and MSI-L, P = 0.025). Sorting the subjects into quartile groups, a statistically significant association was found between high ARNTL2 expression and lymph node involvement (P < 0.001), between high SERPINE1 expression and grading (P < 0.001) and between high SERPINE1 expression and MSI H-L (P < 0.0001). In SW480 cells, a more proliferative model compared to CaCo2 cells, there were higher mRNA levels of ARNTL2 (P < 0.001) and SERPINE1 (P = 0.001). CONCLUSION: ARNTL2 and SERPINE1 expression is increased in colorectal cancer and in a highly proliferative colon cancer cell line and is related to tumor invasiveness and aggressiveness.