p38 MAPK regulates G1-S transition in hypoxic cardiac fibroblasts

miR-212 Promotes Cardiomyocyte Hypertrophy through Regulating Transcription Factor 7 Like 2

To explore the role and possible mechanism of miRNA-212 in heart failure (HF). The rat model of abdominal aortic constriction was constructed, the changes of myocardial morphology were observed by hematoxylin-eosin (HE) staining, and the hypertrophy-related marker molecules were detected by quantitative real-time polymerase chain reaction (qRT-PCR). At the cellular level, phenylephrine and angiotensin II were added to induce cardiomyocyte hypertrophy. The overexpression of miR-212 adenovirus was constructed, and the expression of miR-212 was overexpressed, and its effect on cardiac hypertrophy (CH) was detected by immunofluorescence and qRT-PCR. Then, the mechanism of miR-212 regulating CH was verified by website prediction, luciferase reporter gene assay, qRT-PCR, and western blotting assay. In the successfully constructed rat model of abdominal aortic constriction and cardiomyocyte hypertrophy, ANP and myh7 were dramatically increased, myh6 expression was decreased, and miRNA-212 expression was increased. Overexpression of miRNA-212 in cardiomyocytes can promote cardiomyocyte hypertrophy, while knocking down miR-212 in cardiomyocytes can partially reverse cell hypertrophy. In addition, miR-212 targets TCF7L2 and inhibits the expression of this gene. miRNA-212 targets TCF7L2 and inhibits the expression of this gene, possibly through this pathway to promote cardiomyocyte hypertrophy.

Up-down regulation of HIF-1α in cancer progression

Hypoxia induicible factor-1 alpha (HIF-1α) is a key transcription factor in cancer progression and target therapy in cancer. HIF-1α acts differently depending on presence or absence of Oxygen. In an oxygen-immersed environment, HIF-1α completely deactivated and destroyed by the ubiquitin proteasome pathway (UPP). In contrast, in the oxygen-free environment, it escapes destruction and enters to the nucleus of cells then upregulates many genes involved in cancer progression. Overexpressed HIF-1α and downstream genes support cancer progression through various mechanisms including angiogenesis, proliferation and survival of cells, metabolism reprogramming, invasion and metastasis, cancer stem cell maintenance, induction of genetic instability, and treatment resistance. HIF-1α can be provoked by signaling pathways unrelated to hypoxia during cancer progression. Therefore, cancer development and progression can be modulated by targeting HIF-1α and its downstream signaling molecules. In this regard, HIF-1α inhibitors which are categorized into the agents that regulate HIF-1α in gene, mRNA and protein levels used as an efficient way in cancer treatment. Also, HIF-1α expression can be negatively affected by the agents suppressing the activation of mTOR, PI3k/Akt and MAPK pathways.

Regenerative cross talk between cardiac cells and macrophages

Aside from the first week postnatal, murine heart regeneration is restricted and responses to damage follow classic fibrotic remodeling. Recent transcriptomic analyses have suggested that significant cross talk with the sterile immune response could maintain a more embryonic-like signaling network that promotes acute, transient responses. However, with age, this response-likely mediated by neonatal yolk sac macrophages-then transitions to classical macrophage-mediated, cardiac fibroblast (CF)-based remodeling of the extracellular matrix (ECM) after myocardial infarction (MI). The molecular mechanisms that govern the change with age and drive fibrosis via inflammation are poorly understood. Using multiple ribonucleic acid sequencing (RNA-Seq) datasets, we attempt to resolve the relative contributions of CFs and macrophages in the bulk-healing response of regenerative (postnatal day 1) and nonregenerative hearts (postnatal day 8+). We performed an analysis of bulk RNA-Seq datasets from myocardium and cardiac fibroblasts as well as a single-cell RNA-Seq dataset from cardiac macrophages. MI-specific pathway differences revealed that nonregenerative hearts generated more ECM and had larger matricellular responses correlating with inflammation, produced greater chemotactic gradients to recruit macrophages, and expressed receptors for danger-associated molecular patterns at higher levels than neonates. These changes could result in elevated stress-response pathways compared with neonates, converging at NF-κB and activator protein-1 (AP-1) signaling. Profibrotic gene programs, which greatly diverge on day 3 post MI, lay the foundation for chronic fibrosis, and thus postnatal hearts older than 7 days typically exhibit significantly less regeneration. Our analyses suggest that the macrophage ontogenetic shift in the heart postnatally could result in detrimental stress signaling that suppresses regeneration.NEW & NOTEWORTHY Immediately postnatal mammalian hearts are able to regenerate after infarction, but the cells, pathways, and molecules that regulate this behavior are unclear. By comparing RNA-Seq datasets from regenerative mouse hearts and older, nonregenerative hearts, we are able to identify biological processes that are hallmarks of regeneration. We find that sterile inflammatory processes are upregulated in nonregenerative hearts, initiating profibrotic gene programs 3 days after myocardial infarction that can cause myocardial disease.

Nucleus, Cytoskeleton, and Mitogen-Activated Protein Kinase p38 Dynamics during In Vitro Maturation of Porcine Oocytes

The mitogen-activated kinase (MAPK) p38, a member of the MAPK subfamily, is conserved in all mammalian cells and plays important roles in response to various physiologic cues, including mitogens and heat shock. In the present study, MAPK p38 protein expression in porcine oocytes was analyzed during in vitro maturation (IVM) by Western blotting and immunocytochemistry. The levels of p-p38 or activated p38 and p38 expression were at the lowest in the germinal vesicle (GV) stage oocyte, gradually rising at the germinal vesicle breakdown (GVBD) and then reaching a plateau throughout the IVM culture (p < 0.05). Similarly, the expression level of total p38 was also lower in the GV oocyte than in the oocyte of other meiotic stages and uprising after GVBD and remained high until the metaphase III (MII) stage (p < 0.05). In the GV stage, phosphorylated p38 (p-p38) was initially detectable in the ooplasm and subsequently became clear around the nucleus and localized in the ooplasm at GVBD (18 h post-culture). During the metaphase I (MI) and metaphase II (MII) stages, p-p38 was evenly distributed throughout the ooplasm after IVM for 30 or 42 h. We found that the subcellular localization increased in p-p38 expression throughout oocyte maturation (p < 0.05) and that dynamic reorganization of the cytoskeleton, including microfilaments and microtubules, was progressively changed during the course of meiotic maturation which was likely to be associated with the activation or networking of p38 with other proteins in supporting oocyte development. In conclusion, the alteration of p38 activation is essential for the regulation of porcine oocyte maturation, accompanied by the progressive reorganization and redistribution of the cytoskeleton and MAPK p38, respectively, in the ooplasm.

NADPH oxidase NOX1 is involved in activation of protein kinase C and premature senescence in early stage diabetic kidney

Increased oxidative stress and activation of protein kinase C (PKC) under hyperglycemia have been implicated in the development of diabetic nephropathy. Because reactive oxygen species derived from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, NOX1 accelerate the translocation of PKC isoforms, NOX1 is postulated to play a causative role in the development of diabetic nephropathy. Hyperglycemia was induced in wild-type and Nox1-deficient mice (KO) by two doses of streptozotocin injection. At 3 weeks after the induction of hyperglycemia, glomeruli and cortical tubules were isolated from kidneys. The mRNA level of Nox1 was significantly upregulated in the renal cortex at 3 weeks of hyperglycemia. Urinary albumin and expression of inflammatory or fibrotic mediators were similarly elevated in diabetic wild-type and KO; however, increases in glomerular volume and mesangial matrix area were attenuated in diabetic KO. Nox1 deficiency significantly reduced the levels of renal thiobarbituric acid-reacting substances and 8-hydroxydeoxyguanosine, membranous translocation of PKCα/β, activity of PKC, and phosphorylation of p38 mitogen-activated protein kinase in the diabetic kidney. Furthermore, increased staining of senescence-associated β-galactosidase in glomeruli and cortical tubules of diabetic mice was significantly suppressed in KO. Whereas the levels of cyclin-dependent kinase inhibitors, p16(INK4A) and p21(Cip1), were equivalent between the genotypes, increased levels of p27(Kip1) and γ-H2AX, a biomarker for DNA double-strand breaks, were significantly attenuated in isolated glomeruli and cortical tubules of diabetic KO. Taken together, NOX1 modulates the p38/p27(Kip1) signaling pathway by activating PKC and promotes premature senescence in early stage diabetic nephropathy.

Effects of delayed motherhood on hippocampal gene expression in offspring rats

While many studies have examined the pregnancy and health-related outcomes of delayed motherhood for women, less is known concerning the potential consequences for their children. This study aims to investigate the effect of delayed motherhood on the hippocampus at the whole genome level. Sprague-Dawley rat females, either at the age of 3 or 12 months, were individually housed with a randomly selected 3-month-old male. The rat whole genome expression chips were used to detect gene expression differences in the hippocampus of newborn rats. The gene expression profile was studied through gene ontology and signal pathway analyses. qRT-PCR was used to determine the mRNA expression of solute carrier family 2 (SLC2A1) and S-phase kinase-associated protein 2 (SKP2). Western blot was used to detect the protein expression of SKP2. Compared to the control group, 1291 differentially expressed genes were detected, including 635 up-regulated genes and 656 down-regulated genes. These differential expressed genes were involved in 110 significant biological process and nine significant signaling pathways, in which the pathway in cancer is the most changed pathway. For SKP2 (up-regulated) and SLC2A1 (up-regulated) genes which were relevant to the pathway in cancer, qRT-PCR results were consistent with gene chip assay results. The upregulation of SKP2 was also demonstrated at protein level. In conclusion, delayed motherhood led to unique patterns of hippocampal gene expression in offspring and the newly identified genes afford a quantitative view of the changes which enable deeper insights into the molecular basis underlying the role of delayed motherhood.

Direct estradiol and diethylstilbestrol actions on early- versus late-stage prostate cancer cells

BACKGROUND

Diethylstilbestrol (DES) and other pharmaceutical estrogens have been used at ≥ µM concentrations to treat advanced prostate tumors, with successes primarily attributed to indirect hypothalamic-pituitary-testicular axis control mechanisms. However, estrogens also directly affect tumor cells, though the mechanisms involved are not well understood.

METHODS

LAPC-4 (androgen-dependent) and PC-3 (androgen-independent) cell viability was measured after estradiol (E2) or DES treatment across wide concentration ranges. We then examined multiple rapid signaling mechanisms at 0.1 nM E2 and 1 µM DES optima including levels of: activation (phosphorylation) for mitogen-activated protein kinases, cell-cycle proteins, and caspase 3, necroptosis, and reactive oxygen species (ROS).

RESULTS

LAPC-4 cells were more responsive than PC-3 cells. Robust and sustained extracellular-regulated kinase activation with E2 , but not DES, correlated with ROS generation and cell death. c-Jun N-terminal kinase was only activated in E2-treated PC-3 cells and was not correlated with caspase 3-mediated apoptosis; necroptosis was not involved. The cell-cycle inhibitor protein p16(INK4A) was phosphorylated in both cell lines by both E2 and DES, but to differing extents. In both cell types, both estrogens activated p38 kinase, which subsequently phosphorylated cyclin D1, tagging it for degradation, except in DES-treated PC-3 cells.

CONCLUSIONS

Cyclin D1 status correlated most closely with disrupted cell cycling as a cause of reduced cell numbers, though other mechanisms also contributed. As low as 0.1 nM E2 effectively elicited these mechanisms, and its use could dramatically improve outcomes for both early- and late-stage prostate cancer patients, while avoiding the side effects of high-dose DES treatment.

Involvement of ERK1/2, p38 MAPK, and PI3K/Akt signaling pathways in the regulation of cell cycle progression by PTHrP in colon adenocarcinoma cells

Parathyroid hormone-related peptide (PTHrP) is distributed in most fetal and adult tissues, and its expression correlates with the severity of colon carcinoma. Recently we obtained evidence that in Caco-2 cells, a cell line from human colorectal adenocarcinoma, exogenous PTHrP increases the number of live cells, via ERK1/2, p38 MAPK, and PI3-kinase and induces the expression of cyclin D1, a cell cycle regulatory protein. In this study, we further investigated the role of PTHrP in the regulation of the cell cycle progression in these intestinal cells. Flow cytometry analysis revealed that PTHrP treatment diminishes the number of cells in the G0/G1 phase and increases the number in both S and G2/M phases. The hormone increases the expression of CDK6 and diminishes the amount of negative cell cycle regulators p27Kip1, p15INK4B, and p53. However, PTHrP does not modify the expression of cyclin D3, CDK4, and p16INK4A. In addition, inhibitors of ERK1/2 (PD98059), p38 MAPK (SB203580), and PI3Kinase (LY294002) reversed PTHrP response in Caco-2 cells. Taken together, our results suggest that PTHrP positively modulates cell cycle progression and changes the expression of proteins involved in cell cycle regulation via ERK1/2, p38 MAPK, and PI3K signaling pathways in Caco-2 cells.

p38α MAPK-mediated induction and interaction of FOXO3a and p53 contribute to the inhibited-growth and induced-apoptosis of human lung adenocarcinoma cells by berberine

Background

Berberine (BBR), a component from traditional Chinese medicine, has been shown to possess anti-tumor activity against a wide spectrum of cancer cells including human lung cancer, but the detailed mechanism underlining this has not been well elucidated.

Methods

In this study, the effect of berberine on cell growth and apoptosis were assessed by MTT, flow cytometry and Hoechst 33258 staining assays. The phosphorylation of p38 MAPK and ERK1/2, and expressions of p38 MAPK isoforms α and β, total ERK1/2, p53, FOXO3a and p21 protein were evaluated by Western Blot analysis. Silencing of p38 MAPK isoform α and β, p53, FOXO3a and p21 were performed by siRNA methods. Exogenous expression of FOXO3a was carried out by electroporated transfection assays.

Results

We showed that BBR significantly inhibited growth and induced cell cycle arrest of non small cell lung cancer (NSCLC) cells in the G0/G1 phase in a dose-dependent manner. Furthermore, we found that BBR increased phosphorylation of p38 MAPK and ERK1/2 in a time-dependent and induced protein expression of tumor suppressor p53 and transcription factor FOXO3a in a dose-dependent fashion. The specific inhibitor of p38 MAPK (SB203580), and silencing of p38α MAPK by small interfering RNAs (siRNAs), but not ERK1/2 inhibitor (PD98059) blocked the stimulatory effects of BBR on protein expression of p53 and FOXO3a. Interestingly, inhibition of p53 using one specific inhibitor (Pifithrin-α) and silencing of p53 using siRNAs overcome the inhibitory effect of BBR on cell growth. Silencing of FOXO3a appeared to attenuate the effect of BBR on p53 expression, cell proliferation and apoptosis. Furthermore, BBR induces the protein expression of cell cycle inhibitor p21 (CIP1/WAF1), which was not observed in cells silencing of p53 or FOXO3α gene. Intriguingly, exogenous expression of FOXO3a enhanced the expression of p21 (CIP1/WAF1) and strengthened BBR-induced apoptosis.

Conclusion

Our results show that BBR inhibits proliferation and induces apoptosis of NSCLC cells through activation of p38α MAPK signaling pathway, followed by induction of the protein expression of p53 and FOXO3a. The latter contribute to the BBR-increased p21 (CIP1/WAF1) protein expression. The exogenous FOXO3a, interaction and mutually exclusive events of p53 and FOXO3a augment the overall response of BBR.

Mechanisms in cardiac fibroblast growth: an obligate role for Skp2 and FOXO3a in ERK1/2 MAPK-dependent regulation of p27kip1

Cardiac fibroblast hyperplasia associated with enhanced matrix deposition is a major determinant of tissue remodeling in several disease states of the heart. However, mechanisms controlling cell cycle progression in cardiac fibroblasts remain unexplored. Identification of cell cycle regulatory elements in these cells is important to develop strategies to check adverse cardiac remodeling under pathological conditions. This study sought to probe the mechanisms underlying ERK1/2-mediated p27Kip1 regulation in mitogenically stimulated cardiac fibroblasts. Addition of 10% fetal calf serum to quiescent cultures of adult rat cardiac fibroblasts promoted ERK1/2 activation, as evidenced by its phosphorylation status. Reduction in [3H]thymidine incorporation into DNA increased population doubling time, flow cytometry, and Western blot analysis showing reduced levels of cyclins D and A, p27Kip1 induction, and retinoblastoma protein (Rb) hypophosphorylation in ERK1/2-inhibited cells indicated ERK1/2 dependence of G1-S transition in cardiac fibroblasts. Lack of p27Kip1 protein in serum-stimulated, ERK1/2-active cells was associated with increased levels of Skp2, an E3 ubiquitin ligase for p27Kip1, whose knockdown by RNA interference induced p27Kip1 expression. Further, forced expression of Skp2 in ERK1/2-inhibited cells downregulated p27Kip1. Transcriptional upregulation of p27Kip1 mRNA in ERK1/2-inhibited cells, demonstrated by real-time PCR, correlated with forkhead box O 3a (FOXO3a) transcription factor activation, shown by gel shift assay. FOXO3a knockdown attenuated p27Kip1 mRNA and protein expression in ERK1/2-inhibited cells. We provide evidence for the first time that, in cardiac fibroblasts, activated ERK1/2 regulates p27Kip1 expression transcriptionally and posttranslationally via FOXO3a- and Skp2-dependent mechanisms. Additionally, this study uncovers interesting interactions between critical cell cycle regulatory elements that are only beginning to be understood.

Role of the ubiquitin proteasome system in the heart

Proper protein turnover is required for cardiac homeostasis and, accordingly, impaired proteasomal function appears to contribute to heart disease. Specific proteasomal degradation mechanisms underlying cardiovascular biology and disease have been identified, and such cellular pathways have been proposed to be targets of clinical relevance. This review summarizes the latest literature regarding the specific E3 ligases involved in heart biology, and the general ways that the proteasome regulates protein quality control in heart disease. The potential for therapeutic intervention in Ubiquitin Proteasome System function in heart disease is discussed.

Posttranslational modifications of the retinoblastoma tumor suppressor protein as determinants of function

The retinoblastoma tumor suppressor protein (pRB) plays an integral role in G1-S checkpoint control and consequently is a frequent target for inactivation in cancer. The RB protein can function as an adaptor, nucleating components such as E2Fs and chromatin regulating enzymes into the same complex. For this reason, pRB's regulation by posttranslational modifications is thought to be critical. pRB is phosphorylated by a number of different kinases such as cyclin dependent kinases (Cdks), p38 MAP kinase, Chk1/2, Abl, and Aurora b. Although phosphorylation of pRB by Cdks has been extensively studied, activities regulated through phosphorylation by other kinases are just starting to be understood. As well as being phosphorylated, pRB is acetylated, methylated, ubiquitylated, and SUMOylated. Acetylation, methylation, and SUMOylation play roles in pRB mediated gene silencing. Ubiquitinylation of pRB promotes its degradation and may be used to regulate apoptosis. Recent proteomic data have revealed that pRB is posttranslationally modified to a much greater extent than previously thought. This new information suggests that many unknown pathways affect pRB regulation. This review focuses on posttranslational modifications of pRB and how they influence its function. The final part of the review summarizes new phosphorylation sites from accumulated proteomic data and discusses the possibilities that might arise from this data.

Hypoxia induces myocardial regeneration in zebrafish

BACKGROUND

Hypoxia plays an important role in many biological/pathological processes. In particular, hypoxia is associated with cardiac ischemia. which, although initially inducing a protective response, will ultimately lead to the death of cardiomyocytes and loss of tissue, severely affecting cardiac functionality. Although myocardial damage/loss remains an insurmountable problem for adult mammals, the same is not true for adult zebrafish, which are able to completely regenerate their heart after extensive injury. Myocardial regeneration in zebrafish involves the dedifferentiation and proliferation of cardiomyocytes to replace the damaged/missing tissue; at present, however, little is known about what factors regulate this process.

METHODS AND RESULTS

We surmised that ventricular amputation would lead to hypoxia induction in the myocardium of zebrafish and that this may play a role in regulating the regeneration of the missing cardiac tissue. Using a combination of O(2) perturbation, conditional transgenics, in vitro cell culture, and microarray analysis, we found that hypoxia induces cardiomyocytes to dedifferentiate and proliferate during heart regeneration in zebrafish and have identified a number of genes that could play a role in this process.

CONCLUSION

These results indicate that hypoxia plays a positive role during heart regeneration, which should be taken into account in future strategies aimed at inducing heart regeneration in humans.

Effect of inhibition of the lysophosphatidic acid receptor 1 on metastasis and metastatic dormancy in breast cancer

BACKGROUND

Previous studies identified the human nonmetastatic gene 23 (NME1, hereafter Nm23-H1) as the first metastasis suppressor gene. An inverse relationship between Nm23-H1 and expression of lysophosphatidic acid receptor 1 gene (LPAR1, also known as EDG2 or hereafter LPA1) has also been reported. However, the effects of LPA1 inhibition on primary tumor size, metastasis, and metastatic dormancy have not been investigated.

METHODS

The LPA1 inhibitor Debio-0719 or LPA1 short hairpinned RNA (shRNA) was used. Primary tumor size and metastasis were investigated using the 4T1 spontaneous metastasis mouse model and the MDA-MB-231T experimental metastasis mouse model (n = 13 mice per group). Proliferation and p38 intracellular signaling in tumors and cell lines were determined by immunohistochemistry and western blot to investigate the effects of LPA1 inhibition on metastatic dormancy. An analysis of variance-based two-tailed t test was used to determine a statistically significant difference between treatment groups.

RESULTS

In the 4T1 spontaneous metastasis mouse model, Debio-0719 inhibited the metastasis of 4T1 cells to the liver (mean = 25.2 liver metastases per histologic section for vehicle-treated mice vs 6.8 for Debio-0719-treated mice, 73.0% reduction, P < .001) and lungs (mean = 6.37 lesions per histologic section for vehicle-treated mice vs 0.73 for Debio-0719-treated mice, 88.5% reduction, P < .001), with no effect on primary tumor size. Similar results were observed using the MDA-MB-231T experimental pulmonary metastasis mouse model. LPA1 shRNA also inhibited metastasis but did not affect primary tumor size. In 4T1 metastases, but not primary tumors, expression of the proliferative markers Ki67 and pErk was reduced by Debio-0719, and phosphorylation of the p38 stress kinase was increased, indicative of metastatic dormancy.

CONCLUSION

The data identify Debio-0719 as a drug candidate with metastasis suppressor activity, inducing dormancy at secondary tumor sites.

Transient MPK6 activation in response to oxygen deprivation and reoxygenation is mediated by mitochondria and aids seedling survival in Arabidopsis

Mitogen-activated protein kinases (MPKs) are regulated by diverse stresses with a reactive oxygen species (ROS) component. Here, we report the rapid and transient activation of MPK3, MPK4 and MPK6 upon oxygen deprivation as well as reoxygenation in seedlings of Arabidopsis thaliana. MPK activation peaked within 2 h of oxygen deprivation and again at a higher magnitude within 5 min of reoxygenation. MPK6 was the predominant kinase regulated by oxygen availability in both aerial and root tissue, except in mpk6 mutants, which displayed compensatory activation of MPK3. A universal consequence of oxygen deprivation in eukaryotes is inhibition of the terminal step of the mitochondrial electron transport chain (mETC). We demonstrate that treatment of seedlings with the mETC inhibitors antimycin A and potassium cyanide under normoxia promotes transient MPK6 and MPK3 activation. Confocal imaging of seedlings provided evidence that both oxygen deprivation and mETC inhibitors stimulate mitochondria-associated ROS production. We found that seedling survival of prolonged oxygen deprivation was improved in transgenics that ectopically overexpress MPK3, MPK4 and MPK6, but the induction of mRNAs associated with low oxygen acclimation responses were not markedly altered in MPK6 overexpression lines or mpk6 loss-of-function mutants. However, distinctions in MPK6 activation potential were correlated with other differences in mRNAs accumulation. Our findings suggest that oxygen deprivation and reoxygenation trigger mitochondrial ROS production to activate MPK signaling, which in turn regulate reversible processes that aid survival of transient oxygen deprivation.