Cell Journal (Yakhteh)
Volume:17 Issue: 1, Spring 2015

Histone acetylation, one of the first and best studied histone post-translational modifications (PTMs), as well as the factors involved in its deposition (writers), binding (readers) and removal (erasers), have been shown to act at the heart of regulatory circuits controlling essential cellular functions. The identification of a variety of competing histone lysine-modifying acyl groups including propionyl, butyryl, 2-hydroxyisobutyryl, crotonyl, malonyl, succinyl and glutaryl, raises numerous questions on their functional significance, the molecular systems that manage their establishment, removal and interplay with the well-known acetylation-based mechanisms. Detailed and large-scale investigations of two of these new histone PTMs, crotonylation and 2-hydroxyisobutyrylation, along with histone acetylation, in the context of male genome programming, where stage-specific gene expression programs are switched on and off in turn, have shed light on their functional contribution to the epigenome for the first time. These initial investigations fired many additional questions, which remain to be explored. This review surveys the major results taken from these two new histone acylations and discusses the new biology that is emerging based on the diversity of histone lysine acylations.

Over the past few decades, actin’s presence in the nucleus has been demonstrated. Actin is a key protein necessary for different nuclear processes. Although actin is well known for its functional role in dynamic behavior of the cytoskeleton, emerging studies are now highlighting new roles for actin. At the present time there is no doubt about the presence of actin in the nucleus. A number of studies have uncovered the functional involvement of actin in nuclear processes. Actin as one of the nuclear components has its own structured and functional rules, such as nuclear matrix association, chromatin remodeling, transcription by RNA polymerases I, II, III and mRNA processing. In this historical review, we attempt to provide an overview of our current understanding of the functions of actin in the nucleus.

The peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor proteins whose functions as transcription factors regulate gene expressions. PPARs play essential roles in the regulation of cellular differentiation, development, and metabolism (carbohydrate, lipid, protein), and tumorigenesis of higher organisms. This study attempts to determine the effect of baicalin, a PPARγ activator, on erythroid differentiation of cluster of differentiation 133+ (CD133+) cord blood hematopoietic stem cells (HSCs). In this experimental study, in order to investigate the effects of the PPARγ agonists baicalin and troglitazone on erythropoiesis, we isolated CD133+ cells from human umbilical cord blood using the MACS method. Isolated cells were cultured in erythroid-inducing medium with or without various amounts of the two PPARγ activators (baicalin and troglitazone). Erythroid differentiation of CD133+ cord blood HSCs were assessed using microscopic morphology analysis, flow cytometric analysis of erythroid surface markers transferrin receptor (TfR) and glycophorin A (GPA) and bycolony forming assay. Microscopic and flow cytometric analysis revealed the erythroid differentiation of CD133+ cord blood HSCs under applied erythroid inducing conditions. Our flow cytometric data showed that the TfR and GPA positive cell population diminished significantly in the presence of either troglitazone or baicalin. The suppression of erythroid differentiation in response to PPARγ agonists was dose-dependent. Erythroid colony-forming ability of HSC decreased significantly after treatment with both PPARγ agonists but troglitazone had a markedly greater effect. Our results have demonstrated that PPARγ agonists modulate erythroid differentiation of CD133+ HSCs, and therefore play an important role in regulation of normal erythropoiesis under physiologic conditions. Thus, considering the availability and application of this herbal remedy for treatment of a wide range of diseases, the inhibitory effect of baicalin on erythropoiesis should be noted.

There are several factors, like environmental agents, neurotrophic factors, serotonin and some hormones such as estrogen, affecting neurogenesis and neural differentiation. Regarding to importance of proliferation and regeneration in central nervous system, and a progressive increase in neurodegenerative diseases, cell therapy is an attractive approach in neuroscience. The aim of the present study was to investigate the effects of sex steroid hormones and basic fibroblast growth factor (bFGF) on neuronal differentiation of mouse bone marrow-derived mesenchymal stem cells (BM-MSCs). This experimental study was established in Kharazmi University. BM was isolated from the bones of femur and tibia of 4-6-week old Naval Medical Research Institute (NMRI) mice, and the cells were cultured. The cells were divided into following 4 groups based on the applied treatments: I. control (no treatment), II. steroid hormones (β-estradiol, progesterone and testosterone), III. bFGF and IV. combination of steroid hormones and bFGF. Immunocytochemistry and flow cytometery analyses were applied for beta III-tubulin (β-III tubulin) and microtubule-associated proteins-2 (MAP-2) in 4 days of treatment for all groups. The cells treated with combination of bFGF and steroid hormones represented more expressions of neural markers as compared to control and to other two groups treated with either bFGF or steroid hormones. This study showed that BM-MSCs can express specific neural markers after receiving bFGF pretreatment that was followed by sex steroid hormones treatment. More investigations are necessary to specify whether steroid hormones and bFGF can be considered for treatment of CNS diseases and disorders.

The neural crest is a transient structure of early vertebrate embryos that generates neural crest cells (NCCs). These cells can migrate throughout the body and produce a diverse array of mature tissue types. Due to the ethical and technical problems surrounding the isolation of these early human embryo cells, researchers have focused on in vitro studies to produce NCCs and increase their knowledge of neural crest development. In this experimental study, we cultured human embryonic stem cells (hESCs) on stromal stem cells from human exfoliated deciduous teeth (SHED) for a two-week period. We used different approaches to characterize these differentiated cells as neural precursor cells (NPCs) and NCCs. In the first co-culture week, hESCs appeared as crater-like structures with marginal rosettes. NPCs derived from these structures expressed the early neural crest marker p75 in addition to numerous other genes associated with neural crest induction such as SNAIL, SLUG, PTX3 and SOX9. Flow cytometry analysis showed 70% of the cells were AP2/P75 positive. Moreover, the cells were able to self-renew, sustain multipotent differentiation potential, and readily form neurospheres in suspension culture. SHED, as an adult stem cell with a neural crest origin, has stromal-derived inducing activity (SDIA) and can be used as an NCC inducer from hESCs. These cells provide an invaluable resource to study neural crest differentiation in both normal and disordered human neural crest development.

Hypertrophic scar involves excessive amounts of collagen in dermal layer and may be painful. Nowadays, we can’t be sure about effectiveness of procedure for hypertrophic scar management. The application of stem cells with natural scaffold has been the best option for treatment of burn wounds and skin defect, in recent decades. Fibrin glue (FG) was among the first of the natural biomaterials applied to enhance skin deformity in burn patients. This study aimed to identify an efficient, minimally invasive and economical transplantation procedure using novel FG from human cord blood for treatment of hypertrophic scar and regulation collagen synthesis. In this case series study, eight patients were selected with hypertrophic scar due to full-thickness burns. Human keratinocytes and fibroblasts derived from adult skin donors were isolated and cultured. They were tested for the expression of cytokeratin 14 and vimentin using immunocytochemistry. FG was prepared from pooled cord blood. Hypertrophic scars were extensively excised then grafted by simply placing the sheet of FG containing autologous fibroblast and keratinocytes. Histological analyses were performed using Hematoxylin and eosin (H&E) and Masson’s Trichrome (MT) staining of the biopsies after 8 weeks. Cultured keratinocytes showed a high level of cytokeratin 14 expression and also fibroblasts showed a high level of vimentin. Histological analyses of skin biopsies after 8 weeks of transplantation revealed re-epithelialization with reduction of hypertrophic scars in 2 patients. These results suggest may be the use of FG from cord blood, which is not more efficient than previous biological transporters and increasing hypertrophic scar relapse, but could lead to decrease pain rate.

Human pluripotent stem cells are self-renewing cells with the ability to differentiate into a variety of cells and are viewed to have great potential in the field of regenerative medicine. Research in pluripotent stem cells holds great promise for patient specific therapy in various diseases. In this study, pluripotent stem cell articles published from 1991 to 2012 were screened and retrieved from Science Citation Index Expanded (SCI-EXPANDED). In this retrospective study, the publication trend, citation trends for top articles, distributions of journals and Web of Science categories were analyzed. Five bibliometric indicators including total articles, independent articles, collaborative articles, first author articles, and corresponding author articles were applied to compare publications between countries and institutions. The impact of top articles changed from year to year. Top cited articles in previous publication years were not the same as recent years. "Induced pluripotent stem cell (s)" and "embryonic stem cell (s)" were the most used author keywords in pluripotent stem cell research. In addition, the winner of the Nobel Prize in physiology or medicine in 2012, Prof. Shinya Yamanaka, published four of the top ten most frequently cited articles. The comprehensive analysis of highly cited articles in the stem cell field could identify milestones and important contributors, giving a historic perspective on scientific progress.

Runt-related transcription factor 2 (RUNX2) and osterix (OSX) as two specific osteoblast transcription factors and distal-less homeobox 5 (DLX5) as a non-specific one are of paramount importance in regulating osteoblast related genes including osteocalcin, bone sialoprotein (BSP), osteopontin and collagen type Iα1. The present study sets out to investigate whether epigenetic regulation of these genes is important in osteoblastic differentiation of mesenchymal stem cells (MSCs). In this experimental study, MSCs were differentiated to osteoblasts under the influence of the osteogenic differentiation medium. DNA and RNA were extracted at days 0, 7, 14 and 21 from MSCs differentiating to osteoblasts. Promoter regions of RUNX2, OSX, DLX5 and BSP were analyzed by methylation-specific PCR (MSP). Gene expression was analyzed during osteoblastic differentiation by quantitative real-time polymerase chain reaction (PCR). MSP analysis revealed that promoter methylation status did not change in RUNX2, DLX5 and BSP during MSC osteoblastic differentiation. In contrast, OSX promoter showed a dynamic change in methylation pattern. Moreover, RUNX2, OSX, DLX5 and BSP promoter regions showed three different methylation patterns during MSC differentiation. Gene expression analyses confirmed these results. The results show that in differentiation of MSCs to osteoblasts, epigenetic regulation of OSX may play a leading role.

CYP2D6, an enzyme, metabolizes a large number of commonly prescribed drugs. Variations in CYP2D6 gene encoding this enzyme have been associated with individual differences in drug metabolism rates. The purpose of our study was to identify some allelic variants of CYP2D6 gene and to detect defective CYP2D6 alleles, as part of a pharmacogenetic screening program. A prospective study was done on 120 participants referred to Royan Institute in 2013. Allele and genotype frequencies for polymorphism of CYP2D6 gene in exons 1 and 4 were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and sequencing on PCR products, respectively. We identified a novel variant of the gene encoding cytochrome P450 2D6 (CYP2D6) at position +90 of intron 4 by sequencing method. This novel polymorphism of CYP2D6 has been deposited in GeneBank® under the accession number KF225465 in Jun 2013. In the current study, we identified novel polymorphism in intron 4. This single nucleotide polymorphism (SNP) is known as +90G>A in the fourth intron.

Coronary artery disease (CAD) is a multi-factorial and heterogenic disease with atherosclerosis plaques formation in internal wall of coronary artery. Plaque formation results to limitation of the blood reaching to myocardium leading to appearance of some problems, such as ischemia, sudden thrombosis veins and myocardial infarction (MI). Several environmental and genetic factors are involved in prevalence and incident of CAD as follows: hypertension, high low density lipoprotein-cholesterol (LDL-C), age, diabetes mellitus, family history of early-onset heart disease and smoking. According to genome wide association studies (GWAS), five polymorphisms in the 9p21 locus seem to be associated with the CAD. We aimed to evaluate the remarkable association of two polymorphisms at 9p21 locus, rs1333049 and rs10757274, with CAD. This experimental study was conducted in Golestan, Aria Hospitals and Genetics Lab of Shahid Chamran University in the city of Ahvaz, Iran, in 2010- 2011. The collected blood samples belonging to 170 CAD patients (case group) and 100 healthy individuals (control group) were analyzed by tetra-primer amplification refractory mutation system (ARMS)-polymerase chain reaction (PCR) technique. The results were analyzed using software package used for statistical analysis (SPSS; SPSS Inc., USA) version 16. A value of p<0.05 and an odd ratio (OR) with 95% confidence intervals (CI) were considered significant. The frequencies of CC, CG and GG genotypes for rs1333049 polymorphism in patients were 18.2, 65.3 and 16.5%, while in controls, the related values were 25, 67 and 8%, respectively. GG genotypes of rs1333049 polymorphism in CAD patients were more than control cases (OR: 0.354, 95%CI: 0.138-0.912, p=0.032). The frequencies of AA, AG and GG genotypes for rs10757274 in CAD patients were 8.2, 58.3 and 33.5%, while in controls, the related values were 35, 63 and 2%, respectively. GG Genotype in rs10757274 polymorphism in CAD patients was found more than control cases (OR: 0.014, 95% CI: 0.003 -0.065, p=0.0001). The rs1333049 polymorphism at 9p21 locus shows a weak association with CAD, whereas rs10757274 polymorphism reveals a significant association with CAD. These variants may help the identification of patients with increased risk for coronary artery disease.

Glioblastoma multiforme (GBM), one of the most common and aggressive malignant brain tumors, is highly resistant to radiotherapy. Numerous approaches have been pursued to find new radiosensitizers. We used a picogreen and colonogenic assay to appraise the DNA damage and cell death in a spheroid culture of GBM cells caused by iodine-131 (I-131) beta radiation in the presence of topotecan (TPT). U87MG cells were cultured as spheroids with approximate diameters of 300 μm. Cells were treated with beta radiation of I-131 (at a dose of 2 Gy) and/ or TPT (1 μg/ml for 2 hours). The numbers of cells that survived were compared with untreated cells using a colonogenic assay. In addition, we evaluated possible DNA damages by the picogreen method. The relation between DNA damage and cell death was assessed in the experimental study of groups. The findings showed that survival fraction (SF) in the I-131+TPT group (39%) was considerably less than the I-131 group (58.92%; p<0.05). The number of single strand breaks (SSB) and double strand breaks (DSB), in the DNA of U87MG cells treated with beta radiation of I-131 and TPT (I-131+TPT) significantly increased compared to cells treated with only I-131 or TPT (p<0.05). The amount of SSB repair was more than DSB repair (p<0.05). The relationship between cell death and DNA damage was close (r≥0.6) and significant (p<0.05) in the irradiated and treated groups. Also the maximum rate of DNA repair occurred 24 hours after the treatments. A significant difference was not observed on other days of the restoration. The findings in the present study indicated that TPT can sensitize U87MG cells to radiation and increase DNA damages. Potentially, TPT can cause an increase in damage from DSB and SSB by its inhibitory effects on topoisomerase enzyme and the cell cycle. The increased complex damages following the use of a genotoxic agent and beta I-131 radiation, causes a significant increase the cell death because of the difficult repair process. By assessing the relationship between DNA damage and cell death, the picogreen method can be useful in predicting colonogenic assay. Consequently, it is suggested that co-treatment with I-131 beta radiation and TPT can improve GBM treatment.

Free radicals generated by ionizing radiation attack various cellular components such as lipids. The lung is a very radiosensitive organ and its damage is a doselimiting factor in radiotherapy treatments. Melatonin (MLT), the major product of the pineal gland acts as a radioprotective agent. This study aims to investigate the radioprotective effects of MLT on malondialdehyde (MDA) levels and histopathological changes in irradiated lungs. In this experimental study, a total of 62 rats were divided into five groups. Group 1 received no MLT and radiation (unT), group 2 received oral MLT (oM), group 3 received oral MLT and their thoracic areas were irradiated with 18 Gy (oMR), group 4 received MLT by intraperitoneal (i.p.) injection and their thoracic areas were irradiated with 18 Gy (ipM-R), group 5 received only 18 Gy radiation in the thoracic area (R). Following radiotherapy, half of the animals in each group were sacrificed at 48 hours for evaluation of lipid peroxidation and early phase lung injuries. Other animals were sacrificed in the eighth week of the experiment for evaluation of the presence of late phase radiation induced lung injuries. Pre-treatment of rats with either i.p injection (p<0.05) and oral administration of MLT (p<0.001) significantly reduced MDA levels in red blood cell (RBC) samples compared to the R group. Furthermore, i.p. injection of MLT decreased MDA levels in plasma and tissue (p<0.05). In the early phase of lung injury, both administration of MLT significantly increased lymphocyte (p<0.05) and macrophage frequency (p<0.001). MLT reduced the lung injury index in the lungs compared to the R group (p<0.05). The result of this study confirms the radioprotective effect of MLT on lipid peroxidation, and in both early and late phases of radiation induced lung injuries in an animal model.

Animal model studies have shown that MSY2 and JHDM2A genes have an important role in spermatogenesis process and fertility of male mice. But the potential role of these genes in human spermatogenesis and fertility is not known yet. Therefore, we evaluated expression ratios of these genes in testis tissues of men with normal and impaired spermatogenesis. In this experimental study, after RNA extraction and cDNA synthesis from 50 non-obstructive azoospermic and 12 normal testis tissues, the expression ratios of genes were evaluated by real time polymerase chain reaction (PCR) technique. Hematoxcylin and eosin (H&E) staining was used for histological classification of testis tissues. For statistical analysis, one way analysis of variance (ANOVA) test was carried out. Our results showed a significant reduction in mRNA level of YBX2 in samples with impaired spermatogenesis (p<0.001) compared to samples with qualitatively normal spermatogenesis and normal spermatogenesis; however, in JHDM2A gene, despite sensible reduction in gene expression level in men with impaired spermatogenesis, no significant differences were shown (p>0.05). Furthermore in YBX2, a significant negative correlation was demonstrated between the efficiency score of spermatogenesis and the threshold cycle (CT) (r=-0.7, p<0.0001), whereas in JHDM2A, this negative correlation was not significant (r=-0.4, p=0.06). Generally, these data indicated that YBX2 and JHDM2A genes may play an important role in male infertility, and suggested that these molecules can act as useful biomarkers for predicting male infertility.

Cigarette is a rich source of oxidants and reactive nitrogen species. Nitric oxide (NO) in high concentration has deleterious effects on human sperm function. Antioxidant defense system in seminal plasma protects spermatozoa from the attack of reactive oxygen metabolites. The purpose of this study was to determine the correlation between cigarette smoking with the NO levels and the total antioxidant capacity (TAC) of the seminal plasma in infertile smoker men and to compare severity of oxidative stress (OS) in them with fertile and infertile non-smoking men. In this cross sectional study, a total of 95 male participants attended the Infertility Clinic of the Fatehmeh-zahra Hospital in Babol, Mazandaran Province, Iran, between 2010 and 2011. They were divided into three groups: I. fertile non-smokers (F.ns; n=32), II. infertile non-smokers (IF.ns; n=30) and III. infertile smokers (IF.s; n=33) according to semen analysis World Health Organization guidelines (WHO, 2001) and smoking data. TAC concentration and NO levels of seminal plasma were measured using the ferric reducing ability of plasma (FRAP) method and the Griess reagent, respectively. Standard sperm parameters were significantly higher in the fertile group than those in the infertile groups, but these differences between the IF.ns and IF.s were not statistically significant. The mean TAC in the seminal plasma was higher in the F.ns>IF.ns>IF.s, respectively, but these differences were not statistically significant among three groups (p= 0.096). In contrast, the mean NO level in the seminal plasma was lower in the F.nsConclusion