Cytogenetic characterization of the TM4 mouse Sertoli cell line. I. Conventional banding techniques, FISH and SKY

4-[1-Ethyl-1-methylhexy]-phenol induces apoptosis and interrupts Ca2+ homeostasis via ROS pathway in Sertoli TM4 cells

Biological effect of an individual nonylphenol (NP) isomer extremely relies upon the side chain structure. This research was designed to evaluate the impact of NP isomer, 4-[1-ethyl-1-methylhexy]-phenol (NP₆₅), on Sertoli cells in vitro. Sertoli TM4 cells were exposed to various concentration (0, 0.1, 1, 10, or 20 μM) of NP₆₅ for 24 h, and the outcomes indicated that treatment of NP₆₅ induced reactive oxygen species (ROS) generation, oxidative stress, and apoptosis for Sertoli TM4 cells. In addition, it was found that NP₆₅ exposure affected homeostasis of Ca²⁺ in Sertoli TM4 cells by increasing cytoplasm [Ca²⁺]i, inhibiting Ca²⁺-ATPase activity and decreasing cyclic adenosine monophosphate (cAMP) concentration. Pretreatment with ROS scavenger, N-acetylcysteine (NAC), attenuated NP₆₅-induced oxidative stress as well as apoptosis for TM4 cells. Furthermore, NAC blocked NP₆₅-induced disorders of Ca²⁺ homeostasis by attenuating the growth of intracellular [Ca²⁺]i and the inhibition of Ca²⁺-ATPase and cAMP activities. Thus, we have demonstrated that NP₆₅ induced apoptosis as well as acted as a potent inhibitor of Ca²⁺-ATPase activity and resulted in disorder of Ca²⁺ homeostasis in Sertoli TM4 cells; ROS participated in the process. Our results supported the view that oxidative stress acted an essential role within the development of apoptosis and Ca²⁺ overload in TM4 cells as a consequence of NP₆₅ stimulation.

Regulation of STUB1 expression and its biological significance in mouse Sertoli cells

STIP1 Homology and U-Box Containing Protein 1 (STUB1), a ubiquitin E3 ligase initially involved in immune responses, has recently emerged as a pleiotropic regulator of different biological systems, including skeletal and male reproduction systems. On the latter, a homozygous mutation in the STUB1 gene has been identified in patients with hypogonadism. However, the pattern of expression and biological actions of STUB1 in testis remains so far unexplored. Herein, we report analyses on the testicular expression of STUB1 in human testes with impaired spermatogenesis and paracrine regulation of STUB1 expression in mouse testis development and the direct effects of ablation STUB1 on Sertoli cell (SC) functions. STUB1 was expressed abundantly in pachytene spermatocytes and SCs, and weakly in spermatogonia and differentiating spermatids in normal human testis. In contrast, Sertoli-specific expression of STUB1 was significantly decreased in the human testes with impaired spermatogenesis. Throughout postnatal development of mouse testis, however, STUB1 was expressed exclusively in the nuclei of the functionally mature SCs. The adjacent germ cell (GC)-derived IL-1α overtly regulated STUB1 expression through promoting the ETS domain transcription factor Elk-1 (ELK1)-mediated transactivation. Importantly, ablation of endogenous STUB1 caused lipid accumulation and senescence in GC co-incubated SCs. Together with previous reports on the stimulatory effects of IL-1α on cell senescence, our findings suggest that STUB1 may serve as an important negative feedback signaling to modulate the magnitude of GCs-derived IL-1α, which is normally maintained at low levels within testis.

Apigenin induces oxidative stress in mouse Sertoli TM4 cells

Background and Aim:

Apigenin (API) is an estrogenic compound found in many plants. Sertoli cells reside in the testis and are a key target of environmental toxicants. This study aimed to examine the cytotoxicity, especially oxidative stress of API in mouse Sertoli TM4 cells.

Materials and Methods:

Mouse Sertoli TM4 cells were treated with 50 and 100 μM API for 48 h. Cell viability, lactate dehydrogenase (LDH) activities, glutathione reductase (GR) activities, production of reactive oxygen species (ROS), and malondialdehyde (MDA) levels were evaluated using various assays.

Results:

Treatment with API at both 50 and 100 μM decreased viability and GR activity but increased LDH activity, ROS production, and MDA levels in mouse Sertoli TM4 cells.

Conclusion:

Exposure to API induced oxidative stress in mouse Sertoli TM4 cells.

TNF-α/ENO1 signaling facilitates testicular phagocytosis by directly activating Elmo1 gene expression in mouse Sertoli cells

Phagocytic clearance of apoptotic germ cells (GCs), as well as residual bodies (RBs) released from developing spermatids, is critical for Sertoli cells (SCs) to maintain inner environment homeostasis within testis. However, the molecular mechanisms controlling the phagocytosis are ill defined. Here, we identify a new role for alpha-enolase (ENO1), a key enzyme during glycolysis, as a molecule that facilitates testicular phagocytosis via transactivation of the engulfment and cell motility 1 (Elmo1) gene. Using immunohistochesmitry and double-labeling immunofluorescence, ENO1 was observed to be expressed exclusively in the nuclei of SCs and its expression correlated with the completion of Sertoli cell differentiation. By incubating TM4 cells with different pharmacological inhibitors and establishing TM4^Tnfr1-/- cells, we demonstrated that Sertoli cell-specific expression of ENO1 was under a delicate paracrine control from apoptotic GCs. In turn, persistent blockade of ENO1 expression by a validated siRNA protocol resulted in the disturbance of spermatogenesis and impairment of male fertility. Furthermore, using chromatin immunoprecipitation, electrophoretic mobility shift assay and luciferase reporter assay, we showed that in the presence of apoptotic GCs, ENO1 binds to the distal region of the Elmo1 promoter and facilitates transactivation of the Elmo1 gene. In agreement, overexpression of ELMO1 ameliorated ENO1 deficiency-induced impairment of phagocytosis in TM4 cells. These data reveal a novel role for Sertoli cell-specific expression of ENO1 in regulating phagocytosis in testis, identify TNF-α and ELMO1 as critical upstream and downstream factors in mediating ENO1 action, and have important implications for understanding paracrine control of Sertoli cell function by adjacent GCs.

Downregulation of steroid hormone receptor expression and activation of cell signal transduction pathways induced by a chiral nonylphenol isomer in mouse sertoli TM4 cells

Nonylphenols (NPs) are considered as important environmental toxicants and potential endocrine disrupting compounds which can disrupt male reproductive system. 4-[1-Ethyl-1-methylhexy] phenol (4-NP₆₅ ) is one of the main isomers of technical nonylphenol mixtures. In the present study, effect of NPs was evaluated from an isomer-specific viewpoint using 4-NP₆₅ . Decreased mRNA expression levels of estrogen receptor (ER)-α, ER-β, androgen receptor (AR) and progesterone receptor (PR) were observed in the cells exposed to 4-NP₆₅ for 24 h. Furthermore, 4-NP₆₅ treatment evoked significant decrease in protein expression levels of ER-α and ER-β. Levels of mullerian inhibiting substance and transferrin were found to change significantly in 4-NP₆₅ challenged cells. Additionally, JNK1/2-MAPK pathway was activated due to 4-NP₆₅ exposure, but not ERK1/2 and p38-MAPK pathways. Meanwhile, 4-NP₆₅ increased the p-Akt level and showed no effects on the Akt level which indicated that Akt pathway was activated by 4-NP₆₅ . In conclusion, these findings have shown that 4-NP₆₅ exposure affected expression of cell receptors and cell signaling pathways in Sertoli TM4 cells. We proposed that molecular mechanism of reproductive damage in Sertoli cells induced by NPs may be mediated by cell receptors and/or cell signal transduction pathways, and that the effects were dependent on the side chain of NP isomers. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 469-476, 2017.

Cytotoxic effects of ZnO nanoparticles on mouse testicular cells

Background

Nanoscience and nanotechnology are developing rapidly, and the applications of nanoparticles (NPs) have been found in several fields. At present, NPs are widely used in traditional consumer and industrial products, however, the properties and safety of NPs are still unclear and there are concerns about their potential environmental and health effects. The aim of the present study was to investigate the potential toxicity of ZnO NPs on testicular cells using both in vitro and in vivo systems in a mouse experimental model.

Methods

ZnO NPs with a crystalline size of 70 nm were characterized with various analytical techniques, including ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and atomic force microscopy. The cytotoxicity of the ZnO NPs was examined in vitro on Leydig cell and Sertoli cell lines, and in vivo on the testes of CD1 mice injected with single doses of ZnO NPs.

Results

ZnO NPs were internalized by Leydig cells and Sertoli cells, and this resulted in cytotoxicity in a time- and dose-dependent manner through the induction of apoptosis. Apoptosis likely occurred as a consequence of DNA damage (detected as γ-H2AX and RAD51 foci) caused by increase in reactive oxygen species associated with loss of mitochondrial membrane potential. In addition, injection of ZnO NPs in male mice caused structural alterations in the seminiferous epithelium and sperm abnormalities.

Conclusion

These results demonstrate that ZnO NPs have the potential to induce apoptosis in testicular cells likely through DNA damage caused by reactive oxygen species, with possible adverse consequences for spermatogenesis and therefore, male fertility. This suggests that evaluating the potential impacts of engineered NPs is essential prior to their mass production, to address both the environmental and human health concerns and also to develop sustainable and safer nanomaterials.

Cytogenetic Characterization of the TM4 Mouse Sertoli Cell Line. II. Chromosome Microdissection, FISH, Scanning Electron Microscopy, and Confocal Laser Scanning Microscopy

The chromosomes and interphase cell nuclei of the permanent mouse Sertoli cell line TM4 were examined by chromosome microdissection, FISH, scanning electron microscopy, and confocal laser scanning microscopy. The already known marker chromosomes m1-m5 were confirmed, and 2 new large marker chromosomes m6 and m7 were characterized. The minute heterochromatic marker chromosomes m4 and m5 were microdissected and their DNA amplified by DOP-PCR. FISH of this DNA probe on TM4 metaphase chromosomes demonstrated that the m4 and m5 marker chromosomes have derived from the centromeric regions of normal telocentric mouse chromosomes. Ectopic pairing of the m4 and m5 marker chromosomes with the centromeric region of any of the other chromosomes (centromeric associations) was apparent in ∼60% of the metaphases. Scanning electron microscopy revealed DNA-protein bridges connecting the centromeric regions of normal chromosomes and the associated m4 and m5 marker chromosomes. Interphase cell nuclei of TM4 Sertoli cells did not exhibit the characteristic morphology of Sertoli cells in the testes of adult mice as shown by fluorescence microscopy and confocal laser scanning microscopy.

Nonylphenol regulates cyclooxygenase-2 expression via Ros-activated NF-κB pathway in sertoli TM4 cells

The aim of this study was to investigate the signaling pathways involved in the cyclooxygenase (COX)-2 regulation induced by nonylphenol (NP) in mouse testis Sertoli TM4 cells. Our results showed that treatment of TM4 cells with NP increased COX-2 protein expression and interleukin-6 (IL)-6 and prostaglandin E2 (PGE2) secretion in a dose-dependent manner. Pretreatment with reactive oxygen species (ROS) scavenger, N-acetylcysteine (NAC), attenuated NP-induced ROS production, COX-2 expression, and IL-6 and PGE2 release in TM4 cells. Exposure to NP stimulated activation of NF-κB, whereas the NF-κB inhibitor, pyrrolidine dithiocarbamate, attenuated NP-enhanced COX-2 expression and IL-6 and PGE2 release in TM4 cells in a dose-dependent manner. Furthermore, NAC blocked NP-induced activation of NF-κB. In addition, inhibition of COX-2 mitigated NP-induced IL-6 release. In conclusion, NP induced ROS generation, activation of NF-κB pathway, COX-2 upregulation, and IL-6 and PGE2 secretion in TM4 cells. NP may regulate COX-2 expression via ROS-activated NF-κB pathway in Sertoli TM4 cells.

Mitogen-activated protein kinase and Akt pathways are involved in 4-n-nonyphenol induced apoptosis in mouse Sertoli TM4 cells

Nonylphenol (NP) is considered an important environmental toxicant, which may disrupt male reproductive system. The aim of this study was to investigate 4-n-nonylphenol (4-n-NP) induced apoptosis and its related mechanism in mouse Sertoli cell line, TM4 cells. Our results showed that NP treatment (0.1, 1, 10, 20 and 30 μM) decreased cell viability and induced apoptosis in the cells, accompanied by alteration of Bcl-2 family mRNA expression, activation of caspases-3, release of Ca(2+), and increase of reactive oxygen species (ROS) generation. Subsequently, it was found that the levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) in the cells were markedly decreased, and maleic dialdehyde (MDA) content was increased by NP treatment. Then activation of the mitogen-activated protein kinases (MAPKs) pathways and inhibition of Akt pathway were simultaneously detected in NP challenged TM4 cells. Taken together, it was concluded that NP induced cytotoxicity and apoptosis in TM4 cells, and the apoptosis may be mediated via MAPKs and Akt pathways in addition to Ca(2+) release and ROS generation.

Spectral karyotyping of human, mouse, rat and ape chromosomes--applications for genetic diagnostics and research

Spectral karyotyping (SKY) is a widely used methodology to identify genetic aberrations. Multicolor fluorescence in situ hybridization using chromosome painting probes in individual colors for all metaphase chromosomes at once is combined with a unique spectral measurement and analysis system to automatically classify normal and aberrant chromosomes. Based on countless studies and investigations in many laboratories worldwide, numerous new chromosome translocations and other aberrations have been identified in clinical and tumor cytogenetics. Thus, gene identification studies have been facilitated resulting in the dissection of tumor development and progression. For example, different translocation partners of the TEL/ETV6 transcription factor that is specially required for hematopoiesis within the bone marrow were identified. Also, the correct classification of complex karyotypes of solid tumors supports the prognostication of cancer patients. Important accomplishments for patients with genetic diseases, leukemias and lymphomas, mesenchymal tumors and solid cancers are summarized and exemplified. Furthermore, studies of disease mechanisms such as centromeric DNA breakage, DNA double strand break repair, telomere shortening and radiation-induced neoplastic transformation have been accompanied by SKY analyses. Besides the hybridization of human chromosomes, mouse karyotyping has also contributed to the comprehensive characterization of mouse models of human disease and for gene therapy studies.

Multicolor spectral karyotyping of rat chromosomes

Rat and mouse have become important animal models to study various human diseases such as cancer. Cytogenetic analysis of the respective karyotypes is frequently required to investigate the causative genetic defects and especially neoplastic cells often show complex chromosome aberrations and many different marker chromosomes. However, structural homogeneity of the chromosomes in these species as well as less pronounced differences in banding patterns make it difficult to assign genetic abnormalities to certain chromosomes by conventional banding techniques. Here we report for the first time the successful application of multicolor spectral karyotyping (SKY) to rat chromosomes, which allows unequivocal identification of all rat chromosomes with the exception of chromosomes 13 and 14 in different colors, thus enabling the elucidation of even complex rearrangements in the rat karyotype. Flow-sorted chromosome specific painting probes for all 22 rat chromosomes (20 autosomes, X, and Y) were combinatorially labeled by a set of five different fluorochromes and hybridized in situ to metaphase spreads of a healthy rat, to diakineses from testicular material, and to cells from a rat FAO hepatoma cell line. Measuring the complete spectrum at each image point by using the SpectraCube((R)) spectral imaging system and respective computer software allowed identification of the individual rat chromosomes by their specific emission spectra. Classification algorithms in the analysis software can then display the rat chromosomes in specific pseudo-colors and automatically order them in a karyotype table. After its successful application to human and mouse chromosomes, spectral karyotyping of rat chromosomes now also allows cytogenetic screening of the complete rat genome by a single hybridization.

Proliferative phase sertoli cells display a developmentally regulated response to activin in vitro

We have used cultures of highly purified, proliferating rat Sertoli cells collected from d 3, 6, and 9 rat pups to investigate the role of activin A on Sertoli cell division. These studies demonstrate that activin A acts directly on d 6 and 9, but not d 3, Sertoli cells to induce proliferation, both alone and synergistically with FSH. In addition to stimulating proliferation, activin A induces secretion of inhibins A and B as determined by specific ELISAs. We demonstrate that the synergy between activin A and FSH is not due to local actions of secreted inhibin or follistatin. We have used real-time fluorometric RT-PCR to demonstrate that activin regulates expression of activin receptor and follistatin mRNA by Sertoli cells. Saturation binding studies using (125)I-activin A indicate that synergy between activin and FSH may be due to increased numbers of activin receptors on the Sertoli cell. Finally, we show that activin A was secreted at high levels by cultured peritubular cells but was undetectable in high purity proliferating Sertoli cell cultures, suggesting that activin A functions as a paracrine factor during postnatal testis development.