Won-Young Lee

Establishment and in vitro culture of porcine spermatogonial germ cells in low temperature culture conditions

The objective of this study was to establish a porcine spermatogonial germ cell (pSGC) line and develop an in vitro culture system. Isolated total testicular cells (TTCs) from 5-day-old porcine testes were primary cultured at 31, 34, and 37°C. Although the time of colony appearance was delayed at 31°C, strong alkaline phosphatase staining, expressions of pluripotency marker genes such as OCT4, NANOG, and THY1, and the gene expressions of the undifferentiated germ cell markers PLZF and protein gene product 9.5 (PGP9.5) were identified compared to 34 and 37°C. Cell cycle analysis for both pSGC and feeder cells at the three temperatures revealed that more pSGCs were in the G2/M phase at 31°C than 37°C at the subculture stage. In vitro, pSGCs could stably maintain undifferentiated germ cell and stem cell characteristics for over 60days during culture at 31°C. Xenotransplantation of pSGCs to immune deficient mice demonstrated a successful colonization and localization on the seminiferous tubule basement membrane in the recipient testes. In conclusion, pSGCs from neonatal porcine were successfully established and cultured for long periods under a low temperature culture environment in vitro.

Characterization of GFRα-1-Positive and GFRα-1-Negative Spermatogonia in Neonatal Pig Testis

Type A spermatogonia, including spermatogonial stem cells, are primary cells that maintain spermatogenesis and produce spermatozoa. Many spermatogonial markers have been reported in rodents. However, few markers have been identified in pig spermatogonia. Despite the lack of information, it is necessary to separate pure spermatogonial cells from whole testicular cells to understand the mechanism of spermatogenic meiosis and to establish spermatogonial stem cells for further biotechnological studies. The purpose of this study was to identify glial cell-derived neurotrophic factor receptor alpha-1 (GFRα-1) as a surface marker for early spermatogonia in neonatal pig testes. Histological analysis of 3-day-old pig testes revealed that type A spermatogonia, which lack heterochromatin, could be distinguished in neonatal pig testes. Immunohistochemistry of neonatal pig testes with GFRα-1 antibody identified that some of the spermatogonial cells expressed GFRα-1 on the cell membrane. Co-immunostaining with both GFRα-1 and protein gene product 9.5 (PGP 9.5) detected PGP 9.5 in all spermatogonia of neonatal pig testes, whereas GFRα-1 was not detected on the surface of some PGP 9.5-positive cells, indicating that some of the spermatogonial cells were PGP 9.5 positive and GFRα-1 negative. After immunomagnetic cell sorting using a GFRα-1 antibody, both GFRα-1-positive and GFRα-1-negative cells expressed PGP 9.5. Identifying the differential mRNA expression of both GFRα-1-positive and GFRα-1-negative cells using reverse transcription-polymerase chain reaction analysis revealed the expression of promyelocytic leukaemia zinc finger, octamer-binding protein 4 and homeobox transcription factor in both cell types. These results suggest that GFRα-1-positive and GFRα-1-negative spermatogonia exist in PGP 9.5-positive spermatogonia during the early stage of pig testes spermatogenesis, and that GFRα-1 can be used for sorting PGP 9.5-expressing spermatogonia.

Two potent transactivation domains in the C‐terminal region of human NANOG mediate transcriptional activation in human embryonic carcinoma cells

The core embryonic stem cell transcription factors Oct4, Sox2, and Nanog are expressed in germ cell tumors (GCTs) and have been proposed to play a regulatory role in tumorigenesis. However, little is known about the mechanism of regulation of tumorigenesis by the complicated network of these proteins. Nanog is a novel homeobox‐containing transcription factor that is expressed in pluripotent cells as well as GCTs. To understand the molecular and functional role of human NANOG (hNANOG) in germ cells, mutagenesis of the C‐terminal domain (CD) of hNANOG and transient transfection assays in NCCIT human embryonic carcinoma cells were carried out to identify critical transactivation motifs. We divided the CD into three putative functional subdomains, CD1, tryptophan‐repeat (WR) subdomain, and CD2. WR subdomain and CD2 independently contained transcriptional potential and, in combination, had a synergistic effect on transcriptional activity, while CD1 was transcriptionally inactive. The glutamine (Q) motif in WR subdomain, and multiple acidic residues in CD2 were required for maximal and synergistic transcriptional activation by the hNANOG CD. The results of the current study contribute to a better understanding of the complicated molecular machinery of stem cell transcription factors and their role in unregulated proliferation in germ cell tumorigenesis. J. Cell. Biochem. 106: 1079–1089, 2009.

Therapeutic efficacy of biochanin A against arsenic-induced renal and cardiac damage in rats

The present study was investigated the effects of biochanin A (BCA) on arsenic toxicity in rats. For this purpose, rats were orally treated with arsenic in the form of sodium meta-arsenite alone (10mg/kg body weight (bw)/day) and co-administered selenium (10mg/kgbw/day) and BCA at different doses (10, 20 and 40mg/kgbw/day) for 6 weeks. Arsenic altered the oxidative stress indices in both renal and cardiac tissues. There was an increase in plasma renal markers, triglyceride, lipoproteins with no alterations in cholesterol levels were noted in arsenic-intoxicated rats. Non-significant changes of phospholipids and free fatty acids levels in the tissues of arsenic-exposed rats. The biochemical disturbances were well correlated with the histological findings in the kidney, but not in the heart. The administration of BCA and selenium significantly reversed the alterations in the above-mentioned parameters in arsenic-intoxicated rats. Our findings revealed the beneficial effects of BCA against arsenic toxicity.

Identification and In Vitro Derivation of Spermatogonia in Beagle Testis

Background In vitro culture of spermatogonial stem cells (SSCs) is important for exploration of SSCs self-renewal, differentiation, and manipulation. There are several reports on rodent SSC cultures; however, data on SSC cultures in domestic animals are limited. To provide basic scientific information on canine SSC cultures, we report canine testes development, and the development of spermatogonia-derived colonies (SDCs) for in vitro cultures. Methodology/Principal Findings Testes from 2-, 3-, and 12-month-old beagles were used for histology, immunohistochemistry, in vitro culture, immunocytochemistry, and PCR. Protein gene product 9.5 (PGP9.5)-positive spermatogonia, both single and paired, were found to be abundant in the testes of 2-month-old beagles. stempro-34 and Dulbeccos modified Eagle medium with 5% fetal bovine serum provided as useful substrates for culture of SDCs, and fibroblast growth factor (FGF) played a key role in colony formation. Colonies were positive for alkaline phosphatase and anti-PGP9.5 staining. The early spermatogonia and stem cell markers such as octamer binding protein 4 (Oct4), Nanog homeobox (Nanog), promyelocytic leukemia zinc finger (PLZF), PGP9.5, and GDNF family receptor alpha-1 (GFRα-1) were expressed in the colonies at higher levels than in the testis tissue. Conclusions Testes of the 2-month-old beagles had abundant single and paired spermatogonia, which can be used for derivation of SDCs, and FGF was important for colony formation.

Transcriptional coactivator undifferentiated embryonic cell transcription factor 1 expressed in spermatogonial stem cells: A putative marker of boar spermatogonia

Spermatogenesis is initiated from spermatogonial stem cells (SSCs), which are derived from gonocytes. Although some rodent SSC markers have been investigated, other species- and developmental stage-specific markers of spermatogonia have not been identified. The objective of this study was to characterize the expression of undifferentiated embryonic cell transcription factor 1 (UTF1) gene as a potential marker for spermatogonia and SSCs in the boar testis. In boar testis tissue at pre-pubertal stages (tissues collected at 5, 30, and 60 days of age), UTF1 gene expression was detected in almost all spermatogonia cells that expressed a protein gene product 9.5 (PGP9.5), and immunocytochemical analysis of isolated total testicular cells showed that 91.14% of cells staining for PGP9.5 also stained for UTF1. However, in boar testis tissue at pubertal and post-pubertal stages (tissues collected at 90, 120, 150, and 180 days of age), UTF1 was not detected in all PGP9.5-positive cells in the basement membrane. While some PGP9.5-positive cells stained for UTF1, other cells stained only for PGP9.5 or UTF1. PGP9.5, UTF1, and NANOG was assessed in in vitro cultures of pig SSCs (pSSCs) from testes collected at 5 days of age. The relative amounts of PGP9.5, NANOG, and UTF1 mRNA were greater in pSSC colonies than in testis and muscle tissue. Thus, the UTF1 gene is expressed in PGP9.5-positive spermatogonia cells of pigs at 5 days of age, and its expression is maintained in cultured pSSC colonies, suggesting that UTF1 is a putative marker for early-stage spermatogonia in the pre-pubertal pig testis. These findings will facilitate the study of spermatogenesis and applications in germ cell research.

Implication of human OCT4 transactivation domains for self-regulatory transcription.

OCT4 plays a crucial role in pluripotency and self-renewal of embryonic stem cells. OCT4 is also expressed in testicular germ cell tumors (GCTs), suggesting the important function of OCT4 as an oncogenic factor in GCTs. To understand the molecular mechanism of human OCT4 (hOCT4) in tumorigenesis as well as stemness, we identified hOCT4 transactivation domains in human embryonic carcinoma cells. Context analyses of heterologous GAL4 and natural hOCT4 revealed that each N-terminal domain or C-terminal domain independently stimulated transcriptional activity, and that both domains are required for synergistic transactivation by deletion mapping analysis. Dose-dependent overexpression of exogenous hOCT4 significantly decreased the transcriptional activity of the hOCT4 promoter. This inhibition was reversed by the removal of one or both domains. These results suggest that the inhibitory effect of hOCT4 is mediated by transactivation domains, and that the self-regulation of hOCT4 may be mediated via a negative feedback loop in pluripotent cells.

Identification of Putative Biomarkers for the Early Stage of Porcine Spermatogonial Stem Cells Using Next-Generation Sequencing.

To identify putative biomarkers of porcine spermatogonial stem cells (pSSCs), total RNA sequencing (RNA-seq) analysis was performed on 5- and 180-day-old porcine testes and on pSSC colonies that were established under low temperature culture conditions as reported previously. In total, 10,184 genes were selected using Cufflink software, followed by a logarithm and quantile normalization of the pairwise scatter plot. The correlation rates of pSSCs compared to 5- and 180-day-old testes were 0.869 and 0.529, respectively and that between 5- and 180-day-old testes was 0.580. Hierarchical clustering data revealed that gene expression patterns of pSSCs were similar to 5-day-old testis. By applying a differential expression filter of four fold or greater, 607 genes were identified between pSSCs and 5-day-old testis, and 2118 genes were identified between the 5- and 180-day-old testes. Among these differentially expressed genes, 293 genes were upregulated and 314 genes were downregulated in the 5-day-old testis compared to pSSCs, and 1106 genes were upregulated and 1012 genes were downregulated in the 180-day-old testis compared to the 5-day-old testis. The following genes upregulated in pSSCs compared to 5-day-old testes were selected for additional analysis: matrix metallopeptidase 9 (MMP9), matrix metallopeptidase 1 (MMP1), glutathione peroxidase 1 (GPX1), chemokine receptor 1 (CCR1), insulin-like growth factor binding protein 3 (IGFBP3), CD14, CD209, and Kruppel-like factor 9 (KLF9). Expression levels of these genes were evaluated in pSSCs and in 5- and 180-day-old porcine testes. In addition, immunohistochemistry analysis confirmed their germ cell-specific expression in 5- and 180-day-old testes. These finding may not only be useful in facilitating the enrichment and sorting of porcine spermatogonia, but may also be useful in the study of the early stages of spermatogenic meiosis.

Biochanin A Ameliorates Arsenic-Induced Hepato- and Hematotoxicity in Rats

Biochanin A (BCA) is a natural organic compound of the phytoestrogenic isoflavone class that has antioxidant and metal chelator properties in the presence of transition metal ions, however, its efficacy in animal models is still obscure. Therefore, the objective of this study was to investigate the protective effects of BCA against arsenic-induced hepatic injury and hematotoxicity in rats. The results suggest that arsenic intoxicated rats showed significantly higher levels of plasma hepatic markers than normal control rats. Furthermore, an increase in lipid peroxidation with depletion of reduced glutathione (GSH) and activities of superoxide dismutase (SOD) and catalase (CAT) occurred in the livers of rats exposed to arsenic. Administration of BCA (20 mg/kg·bw/day) and selenium (3 mg/kg·bw/day) resulted in a significant reversal of hepatic and oxidative stress markers in arsenic-intoxicated rats. A low dose of BCA (10 mg/kg·bw/day) did not show any preventive effect, while a high dose of BCA (40 mg/kg·bw/day) partially prevented all hepatotoxicity events. These biochemical perturbations were supported by histopathological observations of the liver. Our results suggest that administration of BCA (20 mg/kg·bw/day) attenuated the arsenic hepatotoxicity, a property that could contribute to the therapeutic approaches for chronic liver diseases.

Interstitial tissue-specific gene expression in mouse testis by intra-tunica albuguineal injection of recombinant baculovirus

The purpose of this study is to establish a gene delivery system for interstitial tissue-specific protein expression in mice testes using modified recombinant baculovirus. Green fluorescent protein (GFP)-expressing recombinant baculovirus (GFP-baculovirus), in which the insect cell-specific polyhedron promoter was replaced by the cytomegalovirus (CMV)-IE promoter, was used to transfect testicular cells in vitro, and for intra-tunica albuguineal injection of the interstitial tissue of the testis. GFP expression was monitored in frozen testes sections by fluorescence microscopy. Expression of GFP in testicular tissues was also assessed by reverse transcription polymerase chain reaction (RT-PCR), and protein expression was assessed by Western blot. Testicular cells in vitro were infected efficiently by modified recombinant GFP-baculovirus. Intra-tunica albuguineal injection of GFP-baculovirus into the mouse testis resulted in a high level of GFP expression in the interstitial tissues. RT-PCR analysis clearly showed GFP gene expression in the testis, particularly interstitial tissues. Intra-tunica albuguineal injection of a modified baculovirus that encoded recombinant rat insulin-like growth factor binding protein (IGFBP)-5 resulted in an increase in IGFBP-5 in testis and semen. In conclusion, we have developed an efficient delivery system for gene expression in vivo in testicular cells, particularly cells of the interstitial tissue using intra-tunica albuguineal injection of a modified recombinant baculovirus. This method will be particularly relevant for application that requires gene delivery and protein expression in the testicular cells of the outer seminiferous tubule of the testis.