Methylation of cytokines gene promoters in IL-1β-treated human intestinal epithelial cells

Objective and design

Epigenetic regulation is important in the activation of inflammatory cells. In the present study, we evaluated if DNA-methylation variations are involved in Interleukin-1β (IL-1β)-induced intestinal epithelial cells activation.

Materials and methods

Differentiated Caco-2 cells were exposed to IL-1β or to 5-azadeoxycytidine (5-azadC) for 24 or 48 h. Genome-wide methylation status was evaluated, while DNA methylation status at the promoter region of the gene encoding interleukin-6, 8 and 10 (IL-6, 8 and 10) was estimated. The levels of the corresponding gene products as well as DNA methyltransferases (DNMTs) quantity were assessed.

Results

IL-1β decreased genomic methylation of human intestinal epithelial cells and induced demethylation at cg-specific sites at the promoter of pro-inflammatory genes IL6 and IL8; conversely it did not change the methylation of the IL10 promoter. IL-1β also increased the release of IL-6 and IL-8 but did not change the IL-10 expression. Finally, cell exposure to IL-1β decreased the DNMT3b expression, increased DNMT3a and was not able to change DNMT1 expression.

Conclusions

Our results suggest a potential role of IL-1β as modulator of DNA methylation in activated differentiated Caco-2 cell line.

     

Neuronal Shc: a gene of longevity in the brain?

Aging is inevitable to all multi-cellular organisms, and each organism has its own lifespan. The species-specific lifespan seems determined genetically; however little is known about how the lifespan determined. During the last decades accumulative evidence indicates that there is certainly a set of genes that are involved in the lifespan determination. Among those dozens of genes, the Shc gene encoding a phosphotyrosine signal adaptor is of potential interests in mammalian aging and/or longevity determination. Shc is merely one form of a gene family, and accumulative evidence demonstrates the presence of additional Shc homologues that are strongly expressed in the nervous system. We hypothesize that lifespan is regulated primarily by the nervous system and/or brain, and neurally expressed Shc homologues play pivotal roles in relation to the evolution of longevity with quality of life. We discuss herein the recent progress of our understanding of the neuronally expressed Shc genes in comparision with p66-Shc as a candidate for the evolution of long life with higher quality of life in mammals.     

Increased dosage of the RUNX1/AML1 gene: a third mode of RUNX leukemia?

RUNX1/AML1, located on chromosome 21, is a key factor in the generation and maintenance of hematopoietic stem cells and the gene most frequently implicated in human leukemias. Chromosome translocations and point mutations are well-documented genetic alterations in RUNX leukemia (also known as CBF leukemia). In addition, overdosage or overexpression of RUNX1 is suspected to be a third mode of RUNX1 involvement in leukemogenesis. The possibility that this mode might underlie Down syndrome-related leukemias caused by trisomy of chromosome 21 is discussed.     

The regulation of the human corpus luteum steroidogenesis: a hypothesis?

The corpus luteum (CL) is an important endocrine organ in the menstrual cycle and in pregnancy. The regulation of its hormonal production has been extensively studied. The steroidogenic abilities of the CL can be rescued by human chorionic gonadotrophin (HCG) but its role in the maintenance of CL function is not clear. We will discuss the hypothesis that there are fetoplacental factors, other than HCG, that modulate CL steroidogenesis.     

Tobacco: a potential inductor of lipid peroxidation of the human spermatozoon membrane?

OBJECTIVE: To determine the membrane lipid peroxidation of human spermatozoon in a cohort of smokers in comparison of never-smokers. MATERIALS AND METHODS: Malondialdehyde (MDA), a stable product of the membrane lipid peroxidation, was assessed in 25 smokers and in 17 never-smokers. In parallel, an evaluation of sperm characteristics was realized for all the studied patients. RESULTS: For the first time, between smokers and never-smokers, a significative increase of MDA concentrations was found by the U-Mann and Whitney test (0.118 +/- 0.176 vs 0.0392 +/- 0.0117 nmol/10(6) spermatozoa), a decrease of the forward motility (grade A), (18 +/- 8 vs 25 +/- 8%) and total sperm count (265.56 +/- 186.96 x 10(6) vs 399.30 +/- 322.23 x10(6)), and also an increase of tapering heads (6 +/- 4 vs 2 +/- 2%) or morphological stress pattern cells (39 +/- 6 vs 24 +/- 5%). In the smokers group, negative significative correlations were found by the non-parametric Spearman test between the MDA concentrations and the sperm count per mL (r=-0.767, p<0.001), the total sperm count (r=-0.656, p<0.001) and the percentage of normal morphology (r=-0.644, p<0.001). CONCLUSIONS: Given of deleterious effects of tobacco in a large panel of human cells and specially on the male gametes, the increase of spermatozoon membrane MDA concentrations and the sperm abnormalities found in the group of smokers may be linked to cigarette smoking.     

Folliculo-stellate cells of the human pituitary: a type of adult stem cell?

Ultrastructural and immunocytochemical observations of pituitary folliculo-stellate cells (FSC) in a large series of adenomatous and nontumorous human pituitaries led to the following conclusions: (1) The endocrine cells of both the nontumorous and the adenomatous pituitary are capable of transforming into FSC while changing from endocrine to nonendocrine phenotype. (2) As shown on consecutive sections in prolactin cell adenomas with FSC-rich areas including microcyst formation, S-100 protein and glial fibrillary acidic protein (GFAP) immunoreactivities are strongest in the smallest newly formed follicles. The 2 immunoreactivities do not overlap. The epithelium of older microcysts is immunonegative, implying that expression of the 2 markers is restricted to the early phase of FSC formation. (3) Transformation of endocrine cells into FSC may signify retrodifferentiation into their Rathke's pouch derived precursors as suggested by occasional presence of ciliated and/or mucin producing cells in the lining of microcysts. (4) In lymphocytic hypophysitis a marked activation as well as increase of number and size of FSC are evident in areas of ongoing immune destruction supporting their immune role. (5) Considering the multifaceted nature of FSC, it is suggested that they represent a type of pluripotent adult stem cell.     

The candidate gene approach: have murine models informed the study of human SLE?

Genome wide linkage studies in human SLE have identified seven highly significant loci linked to SLE, and more than 20 other loci showing suggestive linkage to disease. However, pin-pointing the susceptibility alleles in candidate genes within these linkage regions is challenging, due the genetic heterogeneity, racial differences and environmental influences on disease aetiology. Utilization of murine models of spontaneous lupus nephritis provide a complementary approach, which may then identify candidate genes for analysis in human cases. This review highlights the utility of cross-species approach to identify and characterize the effect of given candidate genes in lupus. The examples described in this review demonstrate the importance of bringing together both genetic and functional information in human and mouse studies.     

High-field magnetic resonance imaging of brain iron: birth of a biomarker?

The brain has an unusually high concentration of iron, which is distributed in an unusual pattern unlike that in any other organ. The physiological role of this iron and the reasons for this pattern of distribution are not yet understood. There is increasing evidence that several neurodegenerative diseases are associated with altered brain iron metabolism. Understanding these dysmetabolic conditions may provide important information for their diagnosis and treatment. For many years the iron distribution in the human brain could be studied effectively only under postmortem conditions. This situation was changed dramatically by the finding that T2-weighted MR imaging at high field strength (initially 1.5 T) appears to demonstrate the pattern of iron distribution in normal brains and that this imaging technique can detect changes in brain iron concentrations associated with disease states. Up to the present time this imaging capability has been utilized in many research applications but it has not yet been widely applied in the routine diagnosis and management of neurodegenerative disorders. However, recent advances in the basic science of brain iron metabolism, the clinical understanding of neurodegenerative diseases and in MRI technology, particularly in the availability of clinical scanners operating at the higher field strength of 3 T, suggest that iron-dependent MR imaging may soon provide biomarkers capable of characterizing the presence and progression of important neurological disorders. Such biomarkers may be of crucial assistance in the development and utilization of effective new therapies for Alzheimer's and Parkinson's diseases, multiple sclerosis and other iron-related CNS disorders which are difficult to diagnose and treat.     

What are the determinants of gene expression levels and breadths in the human genome?

In complex organisms, different tissues express different genes, which ultimately shape the function and phenotype of each tissue. An important goal of modern biology is to understand how some genes are turned on and off in specific tissues and how the numbers of different gene expression products are determined. These aspects are named 'expression breadth' (or 'tissue specificity') and 'expression level', respectively. Here, we show that we can predict substantial amount of variation in levels and breadths of gene expression using genomic information of each gene. Interestingly, many genomic traits are correlated with both aspects of gene expression in similar directions, suggesting shared molecular pathways. However, to elucidate distinctive molecular mechanisms governing gene expression levels and breadths, we need to identify the relative significance of each genomic trait on these two aspects of gene expression. To this end, we developed a novel multivariate multiple regression method. Using this new method, we show that gene compactness (in particular, the mean size of exons), codon usage bias and non-synonymous rates have a stronger influence on expression levels compared with their effects on expression breadths. In contrast, the propensity of promoter DNA methylation is a stronger indicator of expression breadths than of expression levels. Interestingly, intron DNA methylation exhibits an opposite pattern to the promoter DNA methylation in the human genome, suggesting that DNA methylation may play multiple roles depending upon its genomic targets. Furthermore, synonymous rates have stronger associations with expression breadths than with expression levels in the human genome. These findings provide clues toward distinctive molecular mechanisms regulating different aspects of gene expression.     

Does the development of the perigeniculate nucleus support the notion of a hierarchical progression within the visual pathway?

The development of the visual pathway has been extensively studied. However, despite of the importance of the perigeniculate nucleus within this pathway, there is a lack of information concerning its development. The present study examined the dendritic development of perigeniculate nucleus cells using single cell injections in 400-500 microm thick fixed brain slices from kittens of different ages between postnatal day 0 and postnatal day 125. A total of 189 perigeniculate nucleus cells were reconstructed from serial sections for qualitative and quantitative analysis. Cells during the first month were characterized by an abundance of branch points and appendages. There was a significant (P>0.05), albeit variable, increase in the number of branch points and appendages up to about postnatal day 12 after which the numbers were rapidly reduced over the next two weeks. Similarly, appendage numbers significantly increased over the first two weeks until postnatal day 17 and then fell to near adult levels by postnatal day 34. The majority of branch points and appendages occur within 100-200 microm of the soma (10-30% of the dendritic diameter). The data indicate that perigeniculate nucleus dendritic maturation lags shortly behind that of the retina but may precede that of its dorsal thalamic target, the lateral geniculate nucleus. Thus, it may be that the earlier maturation of the perigeniculate nucleus and its inhibitory input is a necessary requirement for the proper development of retinogeniculate and corticothalamic topographic maps within the dorsal lateral geniculate nucleus and perigeniculate nucleus.     

Postatrophic hyperplasia of the prostate gland: neoplastic precursor or innocent bystander?

Postatrophic hyperplasia (PAH) of the prostate gland often demonstrates overlapping histological features with prostatic adenocarcinoma (PCA). These features include small acinar growth and enlarged nuclei with prominent nucleoli. Recent work has demonstrated that PAH is a proliferative, noninvoluting lesion. PAH is also histologically distinct from simple atrophy (SA), which has intermediate- to large-sized glands, minimal cytoplasm, and inconspicuous nuclei. However, despite overlapping features between PAH and PCA, high-grade prostatic intraepithelial neoplasm (HGPIN) is still considered the only direct neoplastic precursor to PCA. HGPIN resembles PCA in its topographic distribution, cytological appearance, and molecular alterations including chromosome 8p loss and chromosome 8 centromeric gain. To examine the hypothesis that PAH is the earliest histologically distinct precursor to HGPIN or PCA, the frequency, distribution, proliferative state, and chromosome 8 gain of benign prostate, SA, PAH, HGPIN, and PCA were analyzed. Forty radical prostatectomy specimens from men with clinically localized PCA were systematically analyzed. Proliferation was determined by Ki-67 immunohistochemistry (MIB-1) on formalin-fixed, paraffin-embedded tissue and quantified by digital image analysis from a total of 5,510 sample areas with benign, SA, PAH, HGPIN, and PCA. A tissue microarray was constructed to evaluate 8c gain using interphase fluorescence in situ hybridization. SA foci (n = 129) and PAH foci (n = 114) were identified in the 40 cases of which 74% (95 of 129) and 88% (100 of 114) were seen in the peripheral zone, respectively (P = 0.006). PAH and SA were identified adjacent to PCA in 28% (32 of 114) and 14% (18 of 129) of foci examined, respectively (P = 0.007). The median number of proliferating nuclei increased significantly from benign (1.20%), SA (2.67%), PAH (3.62%), HGPIN (6.14%), to PCA (12.00%) (P < 0.001). The median percentage of nuclei with more than three centromeric probe signals (chromosome 8c gain) for SA, HGPIN, PAH, and PCA were 2.1, 2.8, 4.0, and 6.0%, respectively, as compared to benign prostate with 1.3% (P = 0.006). In conclusion, the present study identified a strong topographic association between PAH and PCA. PAH is also seen often to be closely associated with chronic inflammation. Proliferation of PAH is significantly greater than benign prostatic epithelium and SA but less than HGPIN or PCA. Gain of 8c is significantly greater in PAH than benign prostate, SA, and even HGPIN. These findings demonstrate a strong association between PAH and PCA, supporting its role as a neoplastic precursor.