Interactions between mesenchymal stem cells and the immune system

In addition to being multi-potent, mesenchymal stem cells (MSCs) possess immunomodulatory functions that have been investigated as potential treatments in various immune disorders. MSCs can robustly interact with cells of the innate and adaptive immune systems, either through direct cell-cell contact or through their secretome. In this review, we discuss current findings regarding the interplay between MSCs and different immune cell subsets. We also draw attention to the mechanisms involved.

Entire nucleotide sequences of Gossypium raimondii and G. arboreum mitochondrial genomes revealed A-genome species as cytoplasmic donor of the allotetraploid species

Cotton (Gossypium spp.) is commonly grouped into eight diploid genomic groups, designated A-G and K, and an allotetraploid genomic group, AD. Gossypium raimondii (D₅ ) and G. arboreum (A₂ ) are the putative contributors to the progenitor of G. hirsutum (AD₁ ), the economically important fibre-producing cotton species. Mitochondrial DNA from week-old etiolated seedlings was extracted from isolated organelles using discontinuous sucrose density gradient method. Mitochondrial genomes were sequenced, assembled, annotated and analysed in orderly. Gossypium raimondii (D₅ ) and G. arboreum (A₂ ) mitochondrial genomes were provided in this study. The mitochondrial genomes of two diploid species harboured circular genome of 643,914 bp (D₅ ) and 687,482 bp (A₂ ), respectively. They differ in size and number of repeat sequences, both contain illuminating triplicate sequences with 7317 and 10,246 bp, respectively, demonstrating dynamic difference and rearranged genome organisations. Comparing the D₅ and A₂ mitogenomes with mitogenomes of tetraploid Gossypium species (AD₁ , G. hirsutum; AD₂ , G. barbadense), a shared 11 kbp fragment loss was detected in allotetraploid species, three regions shared by G. arboreum (A₂ ), G. hirsutum (AD₁ ) and G. barbadense (AD₂ ), while eight regions were specific to G. raimondii (D₅ ). The presence/absence variations and gene-based phylogeny supported that A-genome is a cytoplasmic donor to the progenitor of allotetraploid species G. hirsutum and G. barbadense. The results present structure variations and phylogeny of Gossypium mitochondrial genome evolution.

Resveratrol Enhances Self-Renewal of Mouse Embryonic Stem Cells

Resveratrol (RSV) has been shown to affect the differentiation of several types of stem cells, while the detailed mechanism is elusive. Here, we aim to investigate the function of RSV in self-renewal of mouse embryonic stem cells (ESCs) and the related mechanisms. In contrast with its reported roles, we found unexpectedly that differentiated ESCs or iPSCs treated by RSV would not show further differentiation, but regained a naïve pluripotency state with higher expressions of core transcriptional factors and with the ability to differentiate into all three germ layers when transplanted in vivo. In accordance with these findings, RSV also enhanced cell cycle progression of ESCs via regulating cell cycle-related proteins. Finally, enhanced activation of JAK/STAT3 signaling pathway and suppressed activation of mTOR were found essential in enhancing the self-renewal of ESCs by RSV. Our finding discovered a novel function of RSV in enhancing the self-renewal of ESCs, and suggested that the timing of treatment and concentration of RSV determined the final effect of it. Our work may contribute to understanding of RSV in the self-renewal maintenance of pluripotent stem cells, and may also provide help to the generation and maintenance of iPSCs in vitro. J. Cell. Biochem. 118: 1928-1935, 2017. © 2017 Wiley Periodicals, Inc.

CD61 promotes the differentiation of canine ADMSCs into PGC-like cells through modulation of TGF-β signaling

Previous studies have shown that CD61 (integrin-β3) promotes the differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) into germ-like cells. However, the mechanism remains unclear. In this study, we showed that overexpression of CD61 in canine adipose-derived mesenchymal stem cells (cADMSCs) promotes their differentiation into primordial germ cell (PGC)-like cells. Quantitative real-time PCR, immunocytochemistry and western blot detected higher levels of PGC-specific markers in CD61-overexpressed cADMSCs compared with those in control cells. Moreover, phosphorylation of Smad2, a downstream mediator of transforming growth factor beta (TGF-β), was increased in CD61-overexpressed cADMSCs than that in control cells. However, the expression of PGC-specific markers was downregulated in cADMSCs treated with a TGF-β inhibitor. These results suggested that CD61 could induce cADMSCs to differentiate into PGC-like cells by relying on the activation of TGF-β pathway. ADMSCs possess a considerable potential in treating the infertility of rare animal species.

DNMT 1 maintains hypermethylation of CAG promoter specific region and prevents expression of exogenous gene in fat-1 transgenic sheep

Methylation is an important issue in gene expression regulation and also in the fields of genetics and reproduction. In this study, we created fat-1 transgenic sheep, investigated the fine-mapping and the modulatory mechanisms of promoter methylation. Sheep fetal fibroblasts were transfected by pCAG-fat1-IRES-EGFP. Monoclonal cell line was screened as nuclear donor and carried out nuclear transfer (441 transgenic cloned embryos, 52 synchronism recipient sheep). Six offsprings were obtained. Expressions of exogenous genes fat-1 and EGFP were detectable in 10 examined tissues and upregulated omega-3 fatty acid content. Interestingly, more or less EGFP negative cells were detectable in the positive transgenic fetal skin cells. EGFP negative and positive cells were sorted by flow cytometry, and their methylation status in the whole promoter region (1701 nt) were investigated by bisulphate sequencing. The fine-mapping of methylation in CAG promoter were proposed. The results suggested that exogenous gene expression was determined by the methylation status from 721–1346 nt and modulated by methylation levels at 101, 108 and 115 nt sites in CAG promoter. To clarify the regulatory mechanism of methylation, examination of four DNA methyltransferases (DNMTs) demonstrated that hypermethylation of CAG promoter is mainly maintained by DNMT 1 in EGFP negative cells. Furthermore, investigation of the cell surface antigen CD34, CD45 and CD166 indicated that EGFP positive and negative cells belong to different types. The present study systematically clarified methylation status of CAG promoter in transgenic sheep and regulatory mechanism, which will provide research strategies for gene expression regulation in transgenic animals.

miR-375 controls porcine pancreatic stem cell fate by targeting 3-phosphoinositide-dependent protein kinase-1 (Pdk1)

OBJECTIVES

miR-375 is one of the highly expressed microRNAs (miRNAs) found in pancreatic islets of both humans and mice. In this study, we investigated functions of miRNA miR-375 in porcine pancreatic stem cells (PSC).

MATERIALS AND METHODS

We transfected mimic and inhibitor of miR-375 in PSCs to measure functional roles of the microRNA and its effects on cell cycle proliferation and cell differentiation were determined. Luciferase assays were also performed to reveal the target gene of miR-375.

RESULTS

Overexpression of miR-375 suppressed proliferation, promoted apoptosis and inhibited differentiation into islet-like cells. PDK1 was identified as being a target of miR-375. Furthermore, we found that overexpression of miR-375 inhibited activation of the PDK1-AKT signalling pathway.

CONCLUSION

miR-375 directly targeted PDK1 in porcine PSCs, suppressing cell proliferation and differentiation into islet-like cells.

Immune cells in liver regeneration

After partial hepatectomy, hepatocytes proliferate to restore mass and function of the liver. Macrophages, natural killer (NK) cells, natural killer T (NKT) cells, dendritic cells (DC), eosinophils, gamma delta T (γδT) cells, and conventional T cells, as well as other subsets of the immune cells residing in the liver control liver regeneration, either through direct interactions with hepatocytes or indirectly by releasing inflammatory cytokines. Here, we review recent progress regarding the immune cells in the liver and their functions during liver regeneration.

Lin28a promotes self-renewal and proliferation of dairy goat spermatogonial stem cells (SSCs) through regulation of mTOR and PI3K/AKT

Lin28a is a conserved RNA-binding protein that plays an important role in development, pluripotency, stemness maintenance, proliferation and self-renewal. Early studies showed that Lin28a serves as a marker of spermatogonial stem cells (SSCs) and promotes the proliferation capacity of mouse SSCs. However, there is little information about Lin28a in livestock SSCs. In this study, we cloned Capra hircus Lin28a CDS and found that it is evolutionarily conserved. Lin28a is widely expressed in different tissues of Capra hircus, but is expressed at a high level in the testis. Lin28a is specifically located in the cytoplasm of Capra hircus spermatogonial stem cells and may also be a marker of dairy goat spermatogonial stem cells. Lin28a promoted proliferation and maintained the self-renewal of GmGSCs-I-SB in vivo and in vitro. Lin28a-overexpressing GmGSCs-I-SB showed an enhanced proliferation rate, which might be due to increased PCNA expression. Moreover, Lin28a maintained the self-renewal of GmGSCs-I-SB by up-regulating the expression of OCT4, SOX2, GFRA1, PLZF and ETV5. Furthermore, we found that Lin28a may activate the AKT, ERK, and mTOR signaling pathways to promote the proliferation and maintain the self-renewal of GmGSCs-I-SB.

p38 MAPK pathway is essential for self-renewal of mouse male germline stem cells (mGSCs)

OBJECTIVES

Male germline stem cells (mGSCs), also called spermatogonial stem cells (SSCs), constantly generate spermatozoa in male animals. A number of preliminary studies on mechanisms of mGSC self-renewal have previously been conducted, revealing that several factors are involved in this regulated process. The p38 MAPK pathway is widely conserved in multiple cell types in vivo, and plays an important role in cell proliferation, differentiation, inflammation and apoptosis. However, its role in self-renewal of mGSCs has not hitherto been determined.

MATERIALS AND METHODS

Here, the mouse mGSCs were cultured and their identity was verified by semi-RT-PCR, alkaline phosphatase (AP) staining and immunofluorescence staining. Then, the p38 MAPK pathway was blocked by p38 MAPK-specific inhibitor SB202190. mGSC self-renewal ability was then analysed by observation of morphology, cell number, cell growth analysis, TUNEL incorporation assay and cell cycle analysis.

RESULTS

Results showed that mouse mGSC self-renewal ability was significantly inhibited by SB202190.

CONCLUSIONS

This study showed for the first time that the p38 MAPK pathway plays a key role in maintaining self-renewal capacity of mouse mGSCs, which offers a new self-renewal pathway for these cells and contributes to overall knowledge of the mechanisms of mGSC self-renewal.

The Modification of Tet1 in Male Germline Stem Cells and Interact with PCNA, HDAC1 to promote their Self-renewal and Proliferation

Epigenetic modification plays key roles in spermatogenesis, especially DNA methylation dynamic is important in sustaining normal spermatogenesis. Ten-eleven translocation 1 (Tet1) is not only a key demethylase, which works in specific gene regions, but also crosstalks with partners to regulate epigenetic progress as protein complexes. Dairy goat is an important livestock in China, while the unstable culture system in vitro inhibits optimization of new dairy goat species. The study of epigenetic modification in male germline stem cells (mGSCs) is beneficial to the optimization of adult stem cell culture system in vitro, and the improvement of sperm quality and breeding of selected livestock. In our study, we not only analyzed the morphology, gene expression, DNA methylation and histone methylation dynamic in mouse Tet1 (mTet1) modified mGSCs, we also analyzed the stemness ability by in vivo transplantation and explored the functional mechanism of Tet1 in dairy goat mGSCs. The results showed mTet1 modified mGSCs had better self-renewal and proliferation ability than wild-type mGSCs, mTet1 could also up-regulate JMJD3 to decrease H3K27me3, which also showed to suppress the MEK-ERK pathway. Furthermore, Co-IP analysis demonstrated that TET1 interact with PCNA and HDAC1 by forming protein complexes to comprehensively regulate dairy goat mGSCs and spermatogenesis.

Disruption of FGF5 in Cashmere Goats Using CRISPR/Cas9 Results in More Secondary Hair Follicles and Longer Fibers

Precision genetic engineering accelerates the genetic improvement of livestock for agriculture and biomedicine. We have recently reported our success in producing gene-modified goats using the CRISPR/Cas9 system through microinjection of Cas9 mRNA and sgRNAs targeting the MSTN and FGF5 genes in goat embryos. By investigating the influence of gene modification on the phenotypes of Cas9-mediated goats, we herein demonstrate that the utility of this approach involving the disruption of FGF5 results in increased number of second hair follicles and enhanced fiber length in Cas9-mediated goats, suggesting more cashmere will be produced. The effects of genome modifications were characterized using H&E and immunohistochemistry staining, quantitative PCR, and western blotting techniques. These results indicated that the gene modifications induced by the disruption of FGF5 had occurred at the morphological and genetic levels. We further show that the knockout alleles were likely capable of germline transmission, which is essential for goat population expansion. These results provide sufficient evidences of the merit of using the CRISPR/Cas9 approach for the generation of gene-modified goats displaying the corresponding mutant phenotypes.

Colocalization of cerebral iron with Amyloid beta in Mild Cognitive Impairment

Quantitative Susceptibility Mapping (QSM) MRI at 7 Tesla and 11-Carbon Pittsburgh-Compound-B PET were used for investigating the relationship between brain iron and Amyloid beta (Aβ) plaque-load in a context of increased risk for Alzheimer's disease (AD), as reflected by the Apolipoprotein E ε4 (APOE-e4) allele and mild cognitive impairment (MCI) in elderly subjects. Carriers of APOE-e4 with normal cognition had higher cortical Aβ-plaque-load than non-carriers. In MCI an association between APOE-e4 and higher Aβ-plaque-load was observable both for cortical and subcortical brain-regions. APOE-e4 and MCI was also associated with higher cortical iron. Moreover, cerebral iron significantly affected functional coupling, and was furthermore associated with increased Aβ-plaque-load (R²-adjusted = 0.80, p < 0.001) and APOE-e4 carrier status (p < 0.001) in MCI. This study confirms earlier reports on an association between increased brain iron-burden and risk for neurocognitive dysfunction due to AD, and indicates that disease-progression is conferred by spatial colocalization of brain iron deposits with Aβ-plaques.

Autophagy stimulated proliferation of porcine PSCs might be regulated by the canonical Wnt signaling pathway

Porcine pancreatic stem cells (PSCs) are one kind of the potential cells for treatment of human diabetes. Autophagy is a highly conserved cellular degradation process in which it helps to maintain the balance between the synthesis, degradation and subsequent recycling of cellular components. However, how autophagy contributes to PSCs has not yet been investigated. Here, we established GFP-LC3 transfected porcine PSC lines in which the accumulation of autophagosomes can be efficiently visualized to evaluate the autophagic activity. Moreover, we observed that starved PSCs which showed increased autophagic activity exhibited an increased tendency to proliferate through the results of BrdU, flow cytometry and western blotting. Furthermore, increased expression of active β-catenin after inducing autophagy indicated that it might be the canonical Wnt signaling that autophagy activated to exert the function on the stimulation of PSCs proliferation. Collectively, these results demonstrated that autophagy stimulated proliferation of PSCs might be regulated by the canonical Wnt signaling pathway. Our results for the first time shed light on a role of autophagy for stimulating the proliferation of porcine PSCs.

Investigation of risk factors for mortality in aged guide dogs: A retrospective cohort study

The overall median lifespan of domestic dogs has been estimated to 9-12 years, but little is known about risk factors for mortality in aged and a priori healthy dogs. The objective of this retrospective cohort study was to determine which characteristics are associated with mortality in aged and a priori healthy guide dogs, in a retrospective cohort study of 116 guide dogs followed from a systematic geriatric examination at the age of 8-10 years old. A geriatric grid collected the clinical data and usual biological parameters were measured at the time of examination. Univariate (Kaplan-Meier estimates) and multivariable (Cox proportional hazard model) survival analyses were used to assess the associations with time to all-cause death. The majority of dogs were Golden Retrievers (n=48) and Labrador Retrievers (n=27). Median age at geriatric examination was 8.9 years. A total of 76 dogs died during follow-up, leading to a median survival time from geriatric examination of 4.4 years. After adjustment for demographic and biological variables, an increased alanine amionotransferase level (adjusted Hazard Ratio (adjusted HR), 6.2; 95% confidence interval [95%CI], 2.0-19.0; P<0.01), presenting skin nodules (adjusted HR, 1.9; 95% CI, 1.0-3.4; P=0.04), and not being a Labrador Retriever (adjusted HR, 3.3; 95%CI, 1.4-10; P<0.01) were independently associated with a shorter time to death. This study documents independent associations of alanine aminotransferase level, skin nodules and breed with mortality in aged guide dogs. These results may be useful for preventive medical care when conducting a geriatric examination in working dogs.

Multiplex gene editing via CRISPR/Cas9 exhibits desirable muscle hypertrophy without detectable off-target effects in sheep

The CRISPR/Cas9 system provides a flexible approach for genome engineering of genetic loci. Here, we successfully achieved precise gene targeting in sheep by co-injecting one-cell-stage embryos with Cas9 mRNA and RNA guides targeting three genes (MSTN, ASIP, and BCO2). We carefully examined the sgRNAs:Cas9-mediated targeting effects in injected embryos, somatic tissues, as well as gonads via cloning and sequencing. The targeting efficiencies in these three genes were within the range of 27–33% in generated lambs, and that of simultaneously targeting the three genes was 5.6%, which demonstrated that micro-injection of zygotes is an efficient approach for generating gene-modified sheep. Interestingly, we observed that disruption of the MSTN gene resulted in the desired muscle hypertrophy that is characterized by enlarged myofibers, thereby providing the first detailed evidence supporting that gene modifications had occurred at both the genetic and morphological levels. In addition, prescreening for the off-target effect of sgRNAs was performed on fibroblasts before microinjection, to ensure that no detectable off-target mutations from founder animals existed. Our findings suggested that the CRISPR/Cas9 method can be exploited as a powerful tool for livestock improvement by simultaneously targeting multiple genes that are responsible for economically significant traits.

Primordial germ cell-like cells derived from canine adipose mesenchymal stem cells

OBJECTIVES

Previous studies have shown that adipose mesenchymal stem cells (AMSCs) share the potency of typical bone marrow mesenchymal stem cells (MSCs); however, there is little information concerning characteristics of canine AMSCs (CAMSCs); it has not previously been made clear whether CAMSCs would be able to differentiate into other cell types.

MATERIALS AND METHODS

In this study, typical AMSC lines were established, and their characteristics including morphology, typical markers and differentiation potentiality were tested.

RESULTS

The cells exhibited typical MSC morphology and were positive for CD90, CD44 and CD166, considered to be MSCs surface markers. They were negative for CD34 and CD45. The CAMSCs also exhibited embryonic stem cell (ESC) markers, including Oct4 and Sox2, at passage 2. In an appropriate microenvironment, CAMSCs differentiated into EBs and were able to produce cells of the three germ layers. These results indicate that established cells were putative adipocyte-derived MSCs, which also displayed properties of ESCs. Moreover, when the CAMSCs were induced by bone morphogenetic protein 4 (BMP4), they differentiated into PGC-like cells (PGCLCs) and male germ-like cells, which were positive for PR domain-containing 1 (Prdm1), PR domain-containing 14 (Prdm14), doublesex and mab-3 related transcription factor (Dmrt1), as well as for promyelocytic leukaemia zinc finger (Plzf). Quantitative real-time PCR (qRT-PCR) and western blotting analysis verified higher expression levels of these markers.

CONCLUSION

This study provides an efficient approach to study germ cell development using CAMSCs.

Karyotype analysis in large sample cases from Shenyang Women's and Children's hospital: a study of 16,294 male infertility patients

To explore that it is necessary to routinely detect chromosomes in infertile patients, we investigated peripheral blood lymphocyte karyotype in 16,294 male infertile patients in the north-east of China and analysed the incidence and type of chromosomal anomaly and polymorphism. G-banding karyotype analysis of peripheral blood lymphocytes was performed in 16,294 cases. Semen analysis was performed three times in all the men. PCR and FISH confirmed the presence of the SRY gene. The rate of chromosomal anomaly in the 16,294 male infertile patients was 4.15% (677/16,294). The rates of chromosomal anomaly were 0.24% in normal semen group, 12.6% in light oligoasthenospermia group, 4.7% in moderate-to-severe oligoasthenospermia group and 9.59% in azoospermia group. There are two male infertile patients with 45,X chromosome karyotype. One X male patient had confirmed the presence of the SRY gene and FISH analysis demonstrated its location on the p arm of chromosome 13. The other X male patient had not found SRY gene in its whole-genome DNA. Meanwhile, sperm motility is slightly oligo-asthenozoospermic at the age of 35-39 and nearly azoospermic at the age of 40-45. As the rates of chromosomal anomaly are 0.24% and 12.6% even in normal semen group and light oligoasthenospermia group, the rates of chromosomal polymorphism are 5.36% and 25.51% in normal semen group and light oligoasthenospermia group, respectively; it is necessary to explore peripheral blood lymphocyte karyotype in all infertile couples. We mentioned that Y, 1, 2, 9 and 12 chromosomes were quite important about male infertility. These findings demonstrate that autosomal retention of SRY can be submicroscopic and emphasise the importance of PCR and FISH in the genetic workup of the monosomic X male. At the same time, it suggested that male infertility might be related to meiotic disturbances with spermatogenetic arrest in Y-autosome translocations, which could result in infertility by reduction of sperm production. Last but not least, ageing is one of the factors that could reduce sperm motility and quality.

Quantitative Susceptibility Mapping Suggests Altered Brain Iron in Premanifest Huntington Disease

BACKGROUND AND PURPOSE

In patients with premanifest (nonsymptomatic) and advanced Huntington disease, changes in brain iron levels in the basal ganglia have been previously reported, especially in the striatum. Quantitative susceptibility mapping by using MR phase imaging allows in vivo measurements of tissue magnetic susceptibility, which has been shown to correlate well with iron levels in brain gray matter and is believed to be more specific than other imaging-based iron measures. The purpose of this study was to investigate the use of magnetic susceptibility as a biomarker of disease progression.

MATERIALS AND METHODS

Fifteen subjects with premanifest Huntington disease and 16 age-matched healthy controls were scanned at 7T. Magnetic susceptibility, effective relaxation, and tissue volume in deep gray matter structures were quantified and compared with genetic and clinical measures.

RESULTS

Subjects with premanifest Huntington disease showed significantly higher susceptibility values in the caudate nucleus, putamen, and globus pallidus, indicating increased iron levels in these structures. Significant decreases in magnetic susceptibility were found in the substantia nigra and hippocampus. In addition, significant volume loss (atrophy) and an increase effective relaxation were observed in the caudate nucleus and putamen. Susceptibility values in the caudate nucleus and putamen were found to be inversely correlated with structure volumes and directly correlated with the genetic burdens, represented by cytosine-adenine-guanine repeat age-product-scaled scores.

CONCLUSIONS

The significant magnetic susceptibility differences between subjects with premanifest Huntington disease and controls and their correlation with genetic burden scores indicate the potential use of magnetic susceptibility as a biomarker of disease progression in premanifest Huntington disease.

Modification of Tet1 and histone methylation dynamics in dairy goat male germline stem cells

OBJECTIVES

Tet (ten-eleven translocation) protein 1 is a key enzyme for DNA demethylation, which modulates DNA methylation and gene transcription. DNA methylation and histone methylation are critical elements in self-renewal of male germline stem cells (mGSCs) and spermatogenesis. mGSCs are the only type of adult stem cells able to achieve intergenerational transfer of genetic information, which is accomplished through differentiated sperm cells. However, numerous epigenetic obstacles including incomplete DNA methylation and histone methylation dynamics make establishment of stable livestock mGSC cell lines difficult. The present study was conducted to detect effects of DNA methylation and histone methylation dynamics in dairy goat mGSCs self-renewal and proliferation, through overexpression of Tet1.

MATERIALS AND METHODS

An immortalized dairy goat mGSC cell line bearing mouse Tet1 (mTet1) gene was screened and characteristics of the cells were assayed by quantitative real-time PCR (qRT-PCR), immunofluorescence assay, western blotting, fluorescence activated cell sorting (FACS) and use of the cell counting kit (CCK8) assay.

RESULTS

The screened immortalized dairy goat mGSC cell line bearing mTet1, called mGSC-mTet1 cells was treated with optimal doxycycline (Dox) concentration to maintain Tet1 gene expression. mGSC-mTet1 cells proliferated at a significantly greater rate than wild-type mGSCs, and mGSCs-specific markers such as proliferating cell nuclear antigen (PCNA), cyclinD1 (CCND1), GDNF family receptor alpha 1 (Gfra1) and endogenic Tet1, Tet2 were upregulated. The cells exhibited not only reduction in level of histone methylation but also changes in nuclear location of that methylation marker. While H3K9me3 was uniformly distributed throughout the nucleus of mGSC-mTet1 cells, it was present in only particular locations in mGSCs. H3K27me3 was distributed surrounding the edges of nuclei of mGSC-mTet1 cells, while it was uniformly distributed throughout nuclei of mGSCs. Our results conclusively demonstrate that modification of mGSCs with mTet1 affected mGSC maintenance and seemed to promote establishment of stable goat mGSC cell lines.

CONCLUSIONS

Taken together, our data suggest that Tet1 had novel and dynamic roles for regulating maintenance of pluripotency and proliferation of mGSCs by forming complexes with PCNA and histone methylation dynamics. This may provide new solutions for mGSCs stability and livestock mGSC cell line establishment.

Genome-wide targets identification of "core" pluripotency transcription factors with integrated features in human embryonic stem cells

Embryonic stem cells (ESCs) play an important role in developmental biology which is still lacking clear molecular mechanisms. The "core" transcription factors (TFs) including OCT4, SOX2 and NANOG are essential for maintaining the stemness of ESCs. But the downstream targets of these "core" TFs are still ambiguous. Based on support vector machine (SVM) technology, this study develops a label method algorithm (LMA) for genome-wide target identification of "core" TFs in humans, which eliminates the need for negative training samples. This method integrates histone modifications and TF binding motifs as identification features. Compared with a previous mapping-convergence (M-C) algorithm, the LMA can provide more stable and reliable predictions. 4796, 3166 and 4384 target genes of OCT4, SOX2 and NANOG, respectively, were identified with the LMA model. Then verifications of the predicted targets were carried out based on their functional consistency and their connection degree in networks from a computational system biology perspective. The results showed that the targets of "core" TFs present higher gene functional similarity and closer connection distance than background levels.

Bovine male germline stem-like cells cultured in serum- and feeder-free medium

Male germline stem cells (mGSCs) presented in male testis are responsible for spermatogenesis during their whole life. However, little information can be found on the culture of bovine mGSCs, and the current culture system needs to be improved. In this study, we compared the effects of several commercial serum-free media and different extra-cellular matrix on the enrichment and cultivation of mGSCs. To find out the best culture condition, the biological characteristics of the cultured cells were evaluated by morphological observation, RT-PCR and immunofluorescent staining. According to the cells' condition in different experiment groups, we found out an efficient cultivation system for bovine mGSCs derived from neonate testis. In this serum- and feeder-free medium, the cultured cells maintained the typical morphology, and expressed specific surface markers of both pluripotent ES cells and mGSCs, including SSEA-1, CD49f, C-MYC, PLZF, GFRα1, LIN28, NANOG, Oct4 and SOX2 in commercial human ESCs medium PeproGrow-hESC + BIO (6-bromoindirubin-3'-oxime). Embryoid bodies, derived from the bovine mGSCs, and were formed by ganging drop culture. The retinoic acid induced bovine mGSCs were positive for Stra8, SCP3, DZAL, EMA1 and VASA, and resembled spermatid cells morphologically. Thus, we found an efficient bovine mGSCs-cultivation system, which is lack in serum and feeder.