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Wanta A, Noguchi K, Sugawara T, Sonoda K, Duangchit S, Wakayama T. Expression of Protein Markers in Spermatogenic and Supporting Sertoli Cells Affected by High Abdominal Temperature in Cryptorchidism Model Mice. J Histochem Cytochem 2023; 71:387-408. [PMID: 37431084 PMCID: PMC10363907 DOI: 10.1369/00221554231185626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 06/12/2023] [Indexed: 07/12/2023] Open
Abstract
Cryptorchidism is a congenital abnormality resulting in increased rates of infertility and testicular cancer. We used cryptorchidism model mice that presented with the translocation of the left testis from the scrotum to the abdominal cavity. Mice underwent the surgical procedure of the left testis at day 0 and were sacrificed at days 3, 5, 7, 14, 21, and 28 post-operatively. The weight of the left cryptorchid testis decreased significantly at days 21 and 28. The morphological changes were observed after 5 days and showed detached spermatogenic cells and abnormal formation of acrosome at day 5, multinucleated giant cells at day 7, and atrophy of seminiferous tubules at days 21 and 28. The high abdominal temperature disrupted the normal expression of cell adhesion molecule-1, Nectin-2, and Nectin-3 which are essential for spermatogenesis. In addition, the pattern and alignment of acetylated tubulin in cryptorchid testes were also changed at days 5, 7, 14, 21, and 28. Ultrastructure of cryptorchid testes revealed giant cells that had been formed by spermatogonia, spermatocytes, and round and elongating spermatids. The study's findings reveal that cryptorchidism's duration is linked to abnormal changes in the testis, impacting protein marker expression in spermatogenic and Sertoli cells. These changes stem from the induction of high abdominal temperature.
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Affiliation(s)
- Arunothai Wanta
- Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
- School of Medicine, Mae Fah Luang University, Chiang Rai, Thailand
| | - Kazuhiro Noguchi
- Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Taichi Sugawara
- Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kayoko Sonoda
- Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Suthat Duangchit
- Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
- Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Tomohiko Wakayama
- Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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Fu J, Liu X, Yin B, Shu P, Peng X. NECL2 regulates blood-testis barrier dynamics in mouse testes. Cell Tissue Res 2023:10.1007/s00441-023-03759-5. [PMID: 36872374 DOI: 10.1007/s00441-023-03759-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 02/08/2023] [Indexed: 03/07/2023]
Abstract
The adhesion protein nectin-like molecule 2 (NECL2) is involved in spermatogenesis and participates in the connections between Sertoli cells and germ cells. Necl2 deficiency leads to infertility in male mice. We found that NECL2 is relatively highly expressed on the cell membranes of preleptotene spermatocytes. It is known that preleptotene spermatocytes pass through the blood-testis barrier (BTB) from the base of the seminiferous tubules to the lumen to complete meiosis. We hypothesized that the NECL2 protein on the surfaces of preleptotene spermatocytes has an effect on the BTB when crossing the barrier. Our results showed that Necl2 deficiency caused the levels of proteins in the BTB to be abnormal, such as those of Claudin 3, claudin 11, and Connexin43. NECL2 interacted and colocalized with adhesion proteins forming the BTB, such as Connexin43, Occludin, and N-cadherin. NECL2 regulated BTB dynamics when preleptotene spermatocytes passed through the barrier, and Necl2 deficiency caused BTB damage. Necl2 deletion significantly affected the testicular transcriptome, especially the expression of spermatogenesis-related genes. These results suggest that before meiosis and spermatid development occur, BTB dynamics regulated by NECL2 are necessary for spermatogenesis.
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Affiliation(s)
- Jun Fu
- National Demonstration Center for Experimental Basic Medical Education, and State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Xiao Liu
- State Key Laboratory of Medical Molecular Biology, and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, No. 5, Dongdan Santiao, Dongcheng District, Beijing, 100005, China
| | - Bin Yin
- State Key Laboratory of Medical Molecular Biology, and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, No. 5, Dongdan Santiao, Dongcheng District, Beijing, 100005, China
| | - Pengcheng Shu
- State Key Laboratory of Medical Molecular Biology, and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, No. 5, Dongdan Santiao, Dongcheng District, Beijing, 100005, China
| | - Xiaozhong Peng
- National Demonstration Center for Experimental Basic Medical Education, and State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China. .,State Key Laboratory of Medical Molecular Biology, and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, No. 5, Dongdan Santiao, Dongcheng District, Beijing, 100005, China.
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Kamijo A, Saitoh Y, Sakamoto T, Kubota H, Yamauchi J, Terada N. Scaffold protein Lin7 family in membrane skeletal protein complex in mouse seminiferous tubules. Histochem Cell Biol 2019; 152:333-343. [PMID: 31410570 DOI: 10.1007/s00418-019-01807-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2019] [Indexed: 01/22/2023]
Abstract
The membrane skeletal complex, protein 4.1G-membrane palmitoylated protein 6 (MPP6), is localized in spermatogonia and early spermatocytes of mouse seminiferous tubules. In this study, we investigated the Lin7 family of scaffolding proteins, which interact with MPP6. By immunohistochemistry, Lin7a and Lin7c were localized in germ cells, and Lin7c had especially strong staining in spermatogonia and early spermatocytes, characterized by staging of seminiferous tubules. By immunoelectron microscopy, Lin7 localization appeared under cell membranes in germ cells. The Lin7 staining pattern in seminiferous tubules was partially similar to that of 4.1G, cell adhesion molecule 1 (CADM1), and melanoma cell adhesion molecule (MCAM). Lin7-positive cells included type A spermatogonia, as revealed by double staining for Lin28a. Lin7 staining became weaker in MPP6-deficient mice by immunohistochemistry and western blotting, indicating that MPP6 transports and maintains Lin7 in germ cells. The histology of seminiferous tubules was unchanged in MPP6-deficient mice compared to that of wild-type mice. In cultured spermatogonial stem cells maintained with glial cell line-derived neurotropic factor (GDNF), Lin7 was clearly expressed and immunolocalized along cell membranes, especially at cell-cell junctions. Thus, Lin7 protein is expressed in germ cells, and Lin7, particularly Lin7c, is a useful marker for early spermatogenesis.
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Affiliation(s)
- Akio Kamijo
- Health Science Division, Department of Medical Sciences, Shinshu University Graduate School of Medicine, Science and Technology, 3-1-1 Asahi, Matsumoto City, Nagano, 390-8621, Japan
| | - Yurika Saitoh
- Health Science Division, Department of Medical Sciences, Shinshu University Graduate School of Medicine, Science and Technology, 3-1-1 Asahi, Matsumoto City, Nagano, 390-8621, Japan.,Center for Medical Education, Teikyo University of Science, Adachi-ku, Tokyo, Japan
| | - Takeharu Sakamoto
- Division of Cellular and Molecular Biology, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan
| | - Hiroshi Kubota
- Laboratory of Cell and Molecular Biology, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Aomori, Japan
| | - Junji Yamauchi
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji City, Tokyo, Japan
| | - Nobuo Terada
- Health Science Division, Department of Medical Sciences, Shinshu University Graduate School of Medicine, Science and Technology, 3-1-1 Asahi, Matsumoto City, Nagano, 390-8621, Japan.
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Bayoumy N, El-Shabrawi M, Nada H. Association of ICAM-1 gene variant rs5498 (1462A>G) with non-obstructive azoospermia. HUM FERTIL 2019; 23:234-238. [PMID: 30704307 DOI: 10.1080/14647273.2019.1566646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The blood testicular barrier (BTB) is a barrier protecting the testes from damage. It also plays an important role in spermatogenesis. The intracellular adhesion molecule-1 (ICAM-1) is a member of the immunoglobulin cell adhesion molecule family and is a constituent component of the BTB. This study was carried out to investigate the association between the single nucleotide polymorphism (SNP) rs5498 in the ICAM-1 gene and non-obstructive azoospermia. A total of 100 male patients with non-obstructive azoospermia and 100 fertile males (healthy control) were included in this study. Genotyping of ICAM-1 gene rs5498 was performed using polymerase chain reaction-restriction enzyme fragment length polymorphism (PCR-RFLP). Both AG and GG genotypes were significantly more prevalent among the infertile men compared to the control group (p < 0.001). The odds ratio (OR) for the polymorphic allele (G) was 2.4 with 95% confidence interval from 1.38 to 3.19 (p < 0.001). The study shows that ICAM-1 rs5498 (1462A>G) SNP is positively associated with an increased risk for obstructive azoospermia, with the genotype AG heterozygotes showing a significantly higher frequency among infertile men.
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Affiliation(s)
- Nervana Bayoumy
- Department of Physiology, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Mohamed El-Shabrawi
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Hesham Nada
- Department of Andrology and Dermatology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
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Choobineh H, Kazemi M, Sadighi Gilani MA, Heydari T, Shokri S, Bazrafkan M, Hassanzadeh G. Testosterone Reduces Spinal Cord Injury-Induced Effects on Male Reproduction by Preventing CADM1 Defect. CELL JOURNAL 2018; 20:138-149. [PMID: 29633590 PMCID: PMC5893284 DOI: 10.22074/cellj.2018.5003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 06/28/2017] [Indexed: 02/05/2023]
Abstract
Objective This study evaluated the effects of exogenous testosterone molecule-1 (CADM1) pathological defect during early
and chronic periods of spinal cord injury (SCI).
Materials and Methods In this experimental study, testosterone was administered immediately or after one week of SCI
induction. Along with quantification of CADM1 gene expression and its immunoreactivity, we evaluated sperm parameters and
serum testosterone level post-SCI.
Results Different grades of abnormalities in sperm parameters and testis architecture were observed along with
significant reductions in the level of CADM1 expression and its immunoreactivity in the seminiferous tubules of both
acute and chronic SCI groups. Exogenous testosterone, by compensating the serum testosterone level. reduced
the percentage of apoptotic and both short head and abnormal sperm froms in the caudal epididymis. Importantly,
the beneficial effects of immediate administration of testosterone were prominent. Increases in the level of CADM1
transcription and its immunoreactivity in the testis of SCI mice treated with testosterone were accompanied by
improvement of sperm motility as well as testicular Johnsen’s and Miller’s criteria.
Conclusion Since immediate testosterone treatment improved the immunoreactivity and transcription level of CADM1,
the observed beneficial effect of exogenouse testosterone can be attributed to its effect on CADM1 dynamics.
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Affiliation(s)
- Hamid Choobineh
- School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran.,Zeoonosis Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahsa Kazemi
- Department of Anatomy, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Tahereh Heydari
- Department of Biology, Islamic Azad University, Parand Branch, Iran
| | - Saeed Shokri
- Department of Anatomy, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Mahshid Bazrafkan
- Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Gholamreza Hassanzadeh
- Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronicaddress:
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Sisakhtnezhad S, Heshmati P. Comparative analysis of single-cell RNA sequencing data from mouse spermatogonial and mesenchymal stem cells to identify differentially expressed genes and transcriptional regulators of germline cells. J Cell Physiol 2018; 233:5231-5242. [PMID: 29194616 DOI: 10.1002/jcp.26303] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/28/2017] [Indexed: 12/17/2022]
Abstract
Identifying effective internal factors for regulating germline commitment during development and for maintaining spermatogonial stem cells (SSCs) self-renewal is important to understand the molecular basis of spermatogenesis process, and to develop new protocols for the production of the germline cells from other cell sources. Therefore, this study was designed to investigate single-cell RNA-sequencing data for identification of differentially expressed genes (DEGs) in 12 mouse-derived single SSCs (mSSCs) in compare with 16 mouse-derived single mesenchymal stem cells. We also aimed to find transcriptional regulators of DEGs. Collectively, 1,584 up-regulated DEGs were identified that are associated with 32 biological processes. Moreover, investigation of the expression profiles of genes including in spermatogenesis process revealed that Dazl, Ddx4, Sall4, Fkbp6, Tex15, Tex19.1, Rnf17, Piwil2, Taf7l, Zbtb16, and Cadm1 are presented in the first 30 up-regulated DEGs. We also found 12 basal transcription factors (TFs) and three sequence-specific TFs that control the expression of DEGs. Our findings also indicated that MEIS1, SMC3, TAF1, KAT2A, STAT3, GTF3C2, SIN3A, BDP1, PHC1, and EGR1 are the main central regulators of DEGs in mSSCs. In addition, we collectively detected two significant protein complexes in the protein-protein interactions network for DEGs regulators. Finally, this study introduces the major upstream kinases for the main central regulators of DEGs and the components of core protein complexes. In conclusion, this study provides a molecular blueprint to uncover the molecular mechanisms behind the biology of SSCs and offers a list of candidate factors for cell type conversion approaches and production of germ cells.
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Affiliation(s)
| | - Parvin Heshmati
- Faculty of Dentistry, Department of Endodontics, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Davis BW, Seabury CM, Brashear WA, Li G, Roelke-Parker M, Murphy WJ. Mechanisms Underlying Mammalian Hybrid Sterility in Two Feline Interspecies Models. Mol Biol Evol 2015; 32:2534-46. [PMID: 26006188 PMCID: PMC4592343 DOI: 10.1093/molbev/msv124] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The phenomenon of male sterility in interspecies hybrids has been observed for over a century, however, few genes influencing this recurrent phenotype have been identified. Genetic investigations have been primarily limited to a small number of model organisms, thus limiting our understanding of the underlying molecular basis of this well-documented "rule of speciation." We utilized two interspecies hybrid cat breeds in a genome-wide association study employing the Illumina 63 K single-nucleotide polymorphism array. Collectively, we identified eight autosomal genes/gene regions underlying associations with hybrid male sterility (HMS) involved in the function of the blood-testis barrier, gamete structural development, and transcriptional regulation. We also identified several candidate hybrid sterility regions on the X chromosome, with most residing in close proximity to complex duplicated regions. Differential gene expression analyses revealed significant chromosome-wide upregulation of X chromosome transcripts in testes of sterile hybrids, which were enriched for genes involved in chromatin regulation of gene expression. Our expression results parallel those reported in Mus hybrids, supporting the "Large X-Effect" in mammalian HMS and the potential epigenetic basis for this phenomenon. These results support the value of the interspecies feline model as a powerful tool for comparison to rodent models of HMS, demonstrating unique aspects and potential commonalities that underpin mammalian reproductive isolation.
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Affiliation(s)
- Brian W Davis
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
| | - Christopher M Seabury
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
| | - Wesley A Brashear
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
| | - Gang Li
- College of Veterinary Medicine, Texas A&M University
| | - Melody Roelke-Parker
- College of Veterinary Medicine, Texas A&M University National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - William J Murphy
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
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de Boer P, de Vries M, Ramos L. A mutation study of sperm head shape and motility in the mouse: lessons for the clinic. Andrology 2014; 3:174-202. [PMID: 25511638 DOI: 10.1111/andr.300] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 09/19/2014] [Accepted: 09/24/2014] [Indexed: 12/11/2022]
Abstract
Mouse mutants that show effects on sperm head shape, the sperm tail (flagellum), and motility were analysed in a systematic way. This was achieved by grouping mutations in the following classes: manchette, acrosome, Sertoli cell contact, chromatin remodelling, and mutations involved in complex regulations such as protein (de)phosphorylation and RNA stability, and flagellum/motility mutations. For all mutant phenotypes, flagellum function (motility) was affected. Head shape, including the nucleus, was also affected in spermatozoa of most mouse models, though with considerable variation. For the mutants that were categorized in the flagellum/motility group, generally normal head shapes were found, even when the flagellum did not develop or only poorly so. Most mutants are sterile, an occasional one semi-sterile. For completeness, the influence of the sex chromosomes on sperm phenotype is included. Functionally, the genes involved can be categorized as regulators of spermiogenesis. When extrapolating these data to human sperm samples, in vivo selection for motility would be the tool for weeding out the products of suboptimal spermiogenesis and epididymal sperm maturation. The striking dependency of motility on proper sperm head development is not easy to understand, but likely is of evolutionary benefit. Also, sperm competition after mating can never act against the long-term multi-generation interest of genetic integrity. Hence, it is plausible to suggest that short-term haplophase fitness i.e., motility, is developmentally integrated with proper nucleus maturation, including genetic integrity to protect multi-generation fitness. We hypothesize that, when the prime defect is in flagellum formation, apparently a feedback loop was not necessary as head morphogenesis in these mutants is mostly normal. Extrapolating to human-assisted reproductive techniques practice, this analysis would supply the arguments for the development of tools to select for motility as a continuous (non-discrete) parameter.
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Affiliation(s)
- P de Boer
- Department of Obstetrics and Gynaecology, Radboud University Medical Centre, Nijmegen, The Netherlands
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Transforming growth factor-β1 (TGF-β1) regulates cell junction restructuring via Smad-mediated repression and clathrin-mediated endocytosis of nectin-like molecule 2 (Necl-2). PLoS One 2013; 8:e64316. [PMID: 23741316 PMCID: PMC3669379 DOI: 10.1371/journal.pone.0064316] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 04/14/2013] [Indexed: 11/19/2022] Open
Abstract
Nectin-like molecule-2 (Necl-2), a junction molecule, is exclusively expressed by spermatogenic cells. It mediates homophilic interaction between germ cells and heterophilic interaction between Sertoli and germ cells. Knockout studies have shown that loss of Necl-2 causes male infertility, suggesting Necl-2-based cell adhesion is crucial for spermatogenesis. Transforming growth factor-βs (TGF-βs) are crucial for regulating cell junction restructuring that are required for spermatogenesis. In the present study, we aim to investigate the mechanism on how TGF-β1 regulates Necl-2 expression to achieve timely junction restructuring in the seminiferous epithelium during spermatogenesis. We have demonstrated that TGF-β1 reduces Necl-2 mRNA and protein levels at both transcriptional and post-translational levels. Using inhibitor and clathrin shRNA, we have revealed that TGF-β1 induces Necl-2 protein degradation via clathrin-dependent endocytosis. Endocytosis assays further confirmed that TGF-β1 accelerates the internalization of Necl-2 protein to cytosol. Immunofluorescence staining also revealed that TGF-β1 effectively removes Necl-2 from cell-cell interface. In addition, TGF-β1 reduces Necl-2 mRNA via down-regulating Necl-2 promoter activity. Mutational studies coupled with knockdown experiments have shown that TGF-β1-induced Necl-2 repression requires activation of Smad proteins. EMSA and ChIP assays further confirmed that TGF-β1 promotes the binding of Smad proteins onto MyoD and CCAATa motifs in vitro and in vivo. Taken together, TGF-β1 is a potent cytokine that provides an effective mechanism in controlling Necl-2 expression in the testis via Smad-dependent gene repression and clathrin-mediated endocytosis.
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Xiao X, Mruk DD, Cheng CY. Intercellular adhesion molecules (ICAMs) and spermatogenesis. Hum Reprod Update 2013; 19:167-86. [PMID: 23287428 DOI: 10.1093/humupd/dms049] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND During the seminiferous epithelial cycle, restructuring takes places at the Sertoli-Sertoli and Sertoli-germ cell interface to accommodate spermatogonia/spermatogonial stem cell renewal via mitosis, cell cycle progression and meiosis, spermiogenesis and spermiation since developing germ cells, in particular spermatids, move 'up and down' the seminiferous epithelium. Furthermore, preleptotene spermatocytes differentiated from type B spermatogonia residing at the basal compartment must traverse the blood-testis barrier (BTB) to enter the adluminal compartment to prepare for meiosis at Stage VIII of the epithelial cycle, a process also accompanied by the release of sperm at spermiation. These cellular events that take place at the opposite ends of the epithelium are co-ordinated by a functional axis designated the apical ectoplasmic specialization (ES)-BTB-basement membrane. However, the regulatory molecules that co-ordinate cellular events in this axis are not known. METHODS Literature was searched at http://www.pubmed.org and http://scholar.google.com to identify published findings regarding intercellular adhesion molecules (ICAMs) and the regulation of this axis. RESULTS Members of the ICAM family, namely ICAM-1 and ICAM-2, and the biologically active soluble ICAM-1 (sICAM-1) are the likely regulatory molecules that co-ordinate these events. sICAM-1 and ICAM-1 have antagonistic effects on the Sertoli cell tight junction-permeability barrier, involved in Sertoli cell BTB restructuring, whereas ICAM-2 is restricted to the apical ES, regulating spermatid adhesion during the epithelial cycle. Studies in other epithelia/endothelia on the role of the ICAM family in regulating cell movement are discussed and this information has been evaluated and integrated into studies of these proteins in the testis to create a hypothetical model, depicting how ICAMs regulate junction restructuring events during spermatogenesis. CONCLUSIONS ICAMs are crucial regulatory molecules of spermatogenesis. The proposed hypothetical model serves as a framework in designing functional experiments for future studies.
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Affiliation(s)
- Xiang Xiao
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10065, USA
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