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Xia K, Luo P, Yu J, He S, Dong L, Gao F, Chen X, Ye Y, Gao Y, Ma Y, Yang C, Zhang Y, Yang Q, Han D, Feng X, Wan Z, Cai H, Ke Q, Wang T, Li W, Tu X, Sun X, Deng C, Xiang AP. Single-cell RNA sequencing reveals transcriptomic landscape and potential targets for human testicular ageing. Hum Reprod 2024:deae199. [PMID: 39241251 DOI: 10.1093/humrep/deae199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/05/2024] [Indexed: 09/08/2024] Open
Abstract
STUDY QUESTION What is the molecular landscape underlying the functional decline of human testicular ageing? SUMMARY ANSWER The present study provides a comprehensive single-cell transcriptomic atlas of testes from young and old humans and offers insights into the molecular mechanisms and potential targets for human testicular ageing. WHAT IS KNOWN ALREADY Testicular ageing is known to cause male age-related fertility decline and hypogonadism. Dysfunction of testicular cells has been considered as a key factor for testicular ageing. STUDY DESIGN, SIZE, DURATION Human testicular biopsies were collected from three young individuals and three old individuals to perform single-cell RNA sequencing (scRNA-seq). The key results were validated in a larger cohort containing human testicular samples from 10 young donors and 10 old donors. PARTICIPANTS/MATERIALS, SETTING, METHODS scRNA-seq was used to identify gene expression signatures for human testicular cells during ageing. Ageing-associated changes of gene expression in spermatogonial stem cells (SSCs) and Leydig cells (LCs) were analysed by gene set enrichment analysis and validated by immunofluorescent and functional assays. Cell-cell communication analysis was performed using CellChat. MAIN RESULTS AND THE ROLE OF CHANCE The single-cell transcriptomic landscape of testes from young and old men was surveyed, revealing age-related changes in germline and somatic niche cells. In-depth evaluation of the gene expression dynamics in germ cells revealed that the disruption of the base-excision repair pathway is a prominent characteristic of old SSCs, suggesting that defective DNA repair in SSCs may serve as a potential driver for increased de novo germline mutations with age. Further analysis of ageing-associated transcriptional changes demonstrated that stress-related changes and cytokine pathways accumulate in old somatic cells. Age-related impairment of redox homeostasis in old LCs was identified and pharmacological treatment with antioxidants alleviated this cellular dysfunction of LCs and promoted testosterone production. Lastly, our results revealed that decreased pleiotrophin signalling was a contributing factor for impaired spermatogenesis in testicular ageing. LARGE SCALE DATA The scRNA-seq sequencing and processed data reported in this paper were deposited at the Genome Sequence Archive (https://ngdc.cncb.ac.cn/), under the accession number HRA002349. LIMITATIONS, REASONS FOR CAUTION Owing to the difficulty in collecting human testis tissue, the sample size was limited. Further in-depth functional and mechanistic studies are warranted in future. WIDER IMPLICATIONS OF THE FINDINGS These findings provide a comprehensive understanding of the cell type-specific mechanisms underlying human testicular ageing at a single-cell resolution, and suggest potential therapeutic targets that may be leveraged to address age-related male fertility decline and hypogonadism. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the National Key Research and Development Program of China (2022YFA1104100), the National Natural Science Foundation of China (32130046, 82171564, 82101669, 82371611, 82371609, 82301796), the Natural Science Foundation of Guangdong Province, China (2022A1515010371), the Major Project of Medical Science and Technology Development Research Center of National Health Planning Commission, China (HDSL202001000), the Open Project of NHC Key Laboratory of Male Reproduction and Genetics (KF202001), the Guangdong Province Regional Joint Fund-Youth Fund Project (2021A1515110921, 2022A1515111201), and the China Postdoctoral Science Foundation (2021M703736). The authors declare no conflict of interest.
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Affiliation(s)
- Kai Xia
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Peng Luo
- Reproductive Medicine Centre, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
- Guangdong Key Laboratory of Reproductive Medicine, Guangzhou, Guangdong, China
| | - Jiajie Yu
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Siyuan He
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Lin Dong
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Feng Gao
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
- Reproductive Medicine Centre, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Xuren Chen
- Reproductive Medicine Centre, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yunlin Ye
- Department of Urology, Sun Yat-Sen University Cancer Centre, Guangzhou, China
| | - Yong Gao
- Reproductive Medicine Centre, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
- Guangdong Key Laboratory of Reproductive Medicine, Guangzhou, Guangdong, China
| | - Yuanchen Ma
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Cuifeng Yang
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yadong Zhang
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Qiyun Yang
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Dayu Han
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Xin Feng
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Zi Wan
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Hongcai Cai
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Qiong Ke
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
- Guangdong Key Laboratory of Reproductive Medicine, Guangzhou, Guangdong, China
| | - Tao Wang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
- National-Local Joint Engineering Research Center for Stem Cells and Regenerative Medicine, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Weiqiang Li
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
- Guangdong Key Laboratory of Reproductive Medicine, Guangzhou, Guangdong, China
- National-Local Joint Engineering Research Center for Stem Cells and Regenerative Medicine, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Xiang'an Tu
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Xiangzhou Sun
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Chunhua Deng
- Department of Urology and Andrology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Andy Peng Xiang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
- National-Local Joint Engineering Research Center for Stem Cells and Regenerative Medicine, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
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Sfakianoudis K, Zikopoulos A, Grigoriadis S, Seretis N, Maziotis E, Anifandis G, Xystra P, Kostoulas C, Giougli U, Pantos K, Simopoulou M, Georgiou I. The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature. Int J Mol Sci 2024; 25:4977. [PMID: 38732193 PMCID: PMC11084717 DOI: 10.3390/ijms25094977] [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: 04/16/2024] [Revised: 04/29/2024] [Accepted: 04/29/2024] [Indexed: 05/13/2024] Open
Abstract
One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.
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Affiliation(s)
- Konstantinos Sfakianoudis
- Centre for Human Reproduction, Genesis Athens Clinic, 14-16, Papanikoli, 15232 Athens, Greece; (K.S.); (K.P.)
| | - Athanasios Zikopoulos
- Laboratory of Medical Genetics, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (A.Z.); (N.S.); (C.K.); (U.G.); (I.G.)
- Obstetrics and Gynecology, Royal Cornwall Hospital, Treliske, Truro TR1 3LJ, UK
| | - Sokratis Grigoriadis
- Department of Physiology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.G.); (E.M.); (P.X.)
| | - Nikolaos Seretis
- Laboratory of Medical Genetics, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (A.Z.); (N.S.); (C.K.); (U.G.); (I.G.)
| | - Evangelos Maziotis
- Department of Physiology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.G.); (E.M.); (P.X.)
| | - George Anifandis
- Department of Obstetrics and Gynecology, Faculty of Medicine, School of Health Sciences, University of Thessaly, 41222 Larisa, Greece;
| | - Paraskevi Xystra
- Department of Physiology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.G.); (E.M.); (P.X.)
| | - Charilaos Kostoulas
- Laboratory of Medical Genetics, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (A.Z.); (N.S.); (C.K.); (U.G.); (I.G.)
| | - Urania Giougli
- Laboratory of Medical Genetics, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (A.Z.); (N.S.); (C.K.); (U.G.); (I.G.)
| | - Konstantinos Pantos
- Centre for Human Reproduction, Genesis Athens Clinic, 14-16, Papanikoli, 15232 Athens, Greece; (K.S.); (K.P.)
| | - Mara Simopoulou
- Department of Physiology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.G.); (E.M.); (P.X.)
| | - Ioannis Georgiou
- Laboratory of Medical Genetics, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (A.Z.); (N.S.); (C.K.); (U.G.); (I.G.)
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Zhu H, Cheng Y, Wang X, Yang X, Liu M, Liu J, Liu S, Wang H, Zhang A, Li R, Ye C, Zhang J, Gao J, Fu X, Wu B. Gss deficiency causes age-related fertility impairment via ROS-triggered ferroptosis in the testes of mice. Cell Death Dis 2023; 14:845. [PMID: 38114454 PMCID: PMC10730895 DOI: 10.1038/s41419-023-06359-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 11/22/2023] [Accepted: 11/30/2023] [Indexed: 12/21/2023]
Abstract
Glutathione synthetase (GSS) catalyzes the final step in the synthesis of glutathione (GSH), a well-established antioxidant. Research on the specific roles of the Gss gene during spermatogenesis remains limited due to the intricate structure of testis. In this study, we identified pachytene spermatocytes as the primary site of GSS expression and generated a mouse model with postnatal deletion of Gss using Stra8-Cre (S8) to investigate the role of GSS in germ cells. The impact of Gss knockout on reducing male fertility is age-dependent and caused by ferroptosis in the testis. The 2-month-old S8/Gss-/- male mice exhibited normal fertility, due to a compensatory increase in GPX4, which prevented the accumulation of ROS. With aging, there was a decline in GPX4 and an increase in ALOX15 levels observed in 8-month-old S8/Gss-/- mice, resulting in the accumulation of ROS, lipid peroxidation, and ultimately testicular ferroptosis. We found that testicular ferroptosis did not affect spermatogonia, but caused meiosis disruption and acrosome heterotopia. Then the resulting aberrant sperm showed lower concentration and abnormal morphology, leading to reduced fertility. Furthermore, these injuries could be functionally rescued by inhibiting ferroptosis through intraperitoneal injection of GSH or Fer-1. In summary, Gss in germ cells play a crucial role in the resistance to oxidative stress injury in aged mice. Our findings deepen the understanding of ferroptosis during spermatogenesis and suggest that inhibiting ferroptosis may be a potential strategy for the treatment of male infertility.
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Affiliation(s)
- Haixia Zhu
- Department of Pharmacology, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250100, China
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China
| | - Yin Cheng
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China
| | - Xianmei Wang
- Department of Reproductive Medicine, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China
| | - Xing Yang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China
| | - Min Liu
- Medical Science and Technology Innovation Center, Shandong First Medical University, Jinan, 250117, China
| | - Jun Liu
- Shandong Aimeng Biological Technology Co., Ltd, Jinan, 250023, China
| | - Shuqiao Liu
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China
| | - Hongxiang Wang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China
| | - Aizhen Zhang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China
| | - Runze Li
- Medical Science and Technology Innovation Center, Shandong First Medical University, Jinan, 250117, China
| | - Chao Ye
- Medical Science and Technology Innovation Center, Shandong First Medical University, Jinan, 250117, China
| | - Jian Zhang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China.
| | - Jiangang Gao
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, 250100, China.
| | - Xiaolong Fu
- Medical Science and Technology Innovation Center, Shandong First Medical University, Jinan, 250117, China.
| | - Bin Wu
- Department of Reproductive Medicine, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China.
- Cheeloo College of Medicine, Shandong University, Jinan, 250012, China.
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4
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Raee P, Tan SC, Najafi S, Zandsalimi F, Low TY, Aghamiri S, Fazeli E, Aghapour M, Mofarahe ZS, Heidari MH, Fathabadi FF, Abdi F, Asouri M, Ahmadi AA, Ghanbarian H. Autophagy, a critical element in the aging male reproductive disorders and prostate cancer: a therapeutic point of view. Reprod Biol Endocrinol 2023; 21:88. [PMID: 37749573 PMCID: PMC10521554 DOI: 10.1186/s12958-023-01134-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/01/2023] [Indexed: 09/27/2023] Open
Abstract
Autophagy is a highly conserved, lysosome-dependent biological mechanism involved in the degradation and recycling of cellular components. There is growing evidence that autophagy is related to male reproductive biology, particularly spermatogenic and endocrinologic processes closely associated with male sexual and reproductive health. In recent decades, problems such as decreasing sperm count, erectile dysfunction, and infertility have worsened. In addition, reproductive health is closely related to overall health and comorbidity in aging men. In this review, we will outline the role of autophagy as a new player in aging male reproductive dysfunction and prostate cancer. We first provide an overview of the mechanisms of autophagy and its role in regulating male reproductive cells. We then focus on the link between autophagy and aging-related diseases. This is followed by a discussion of therapeutic strategies targeting autophagy before we end with limitations of current studies and suggestions for future developments in the field.
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Affiliation(s)
- Pourya Raee
- Student Research Committee, Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shing Cheng Tan
- UKM Medical Molecular Biology Institute, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Sajad Najafi
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, 19395-4719, Iran
| | - Farshid Zandsalimi
- Department of Molecular Medicine, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Teck Yew Low
- UKM Medical Molecular Biology Institute, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Shahin Aghamiri
- Student Research Committee, Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Elham Fazeli
- Mehr Fertility Research Center, Guilan University of Medical Sciences, Rasht, Iran
| | - Mahyar Aghapour
- Department of Dermatology and Allergic Diseases, Ulm University, Ulm, Germany
| | - Zahra Shams Mofarahe
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Hossein Heidari
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Fadaei Fathabadi
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Farid Abdi
- Department of Chemical Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran
| | - Mohsen Asouri
- North Research Center, Pasteur Institute of Iran, Amol, Iran
| | | | - Hossein Ghanbarian
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, 19395-4719, Iran.
- Urogenital Stem Cell Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Patel M, Muthigi A, Laurentino S, Diaz P, Ramasamy R. Male reproductive aging: can men with oligospermia become azoospermic over time? Int J Impot Res 2023; 35:505-508. [PMID: 36253473 DOI: 10.1038/s41443-022-00634-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/02/2022] [Accepted: 10/05/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Mehul Patel
- Desai Sethi Urology Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
| | - Akhil Muthigi
- Desai Sethi Urology Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Sandra Laurentino
- Institute of Reproductive and Regenerative Biology, Centre of Reproductive Medicine and Andrology, University of Münster, Münster, Germany
| | - Parris Diaz
- Desai Sethi Urology Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Ranjith Ramasamy
- Desai Sethi Urology Institute, University of Miami Miller School of Medicine, Miami, FL, USA
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Dong S, Chen C, Zhang J, Gao Y, Zeng X, Zhang X. Testicular aging, male fertility and beyond. Front Endocrinol (Lausanne) 2022; 13:1012119. [PMID: 36313743 PMCID: PMC9606211 DOI: 10.3389/fendo.2022.1012119] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/26/2022] [Indexed: 11/15/2022] Open
Abstract
Normal spermatogenesis and sperm function are crucial for male fertility. The effects of healthy testicular aging and testicular premature aging on spermatogenesis, sperm function, and the spermatogenesis microenvironment cannot be ignored. Compared with younger men, the testis of older men tends to have disturbed spermatogenic processes, sperm abnormalities, sperm dysfunction, and impaired Sertoli and Leydig cells, which ultimately results in male infertility. Various exogenous and endogenous factors also contribute to pathological testicular premature aging, such as adverse environmental stressors and gene mutations. Mechanistically, Y-chromosomal microdeletions, increase in telomere length and oxidative stress, accumulation of DNA damage with decreased repair ability, alterations in epigenetic modifications, miRNA and lncRNA expression abnormalities, have been associated with impaired male fertility due to aging. In recent years, the key molecules and signaling pathways that regulate testicular aging and premature aging have been identified, thereby providing new strategies for diagnosis and treatment. This review provides a comprehensive overview of the underlying mechanisms of aging on spermatogenesis. Furthermore, potential rescue measures for reproductive aging have been discussed. Finally, the inadequacy of testicular aging research and future directions for research have been envisaged to aid in the diagnosis and treatment of testicular aging and premature aging.
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Affiliation(s)
- Shijue Dong
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, China
| | - Chen Chen
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, China
| | - Jiali Zhang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, China
| | - Yuan Gao
- Laboratory Animal Center, Nantong University, Nantong, China
| | - Xuhui Zeng
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, China
| | - Xiaoning Zhang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, China
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Ashapkin V, Suvorov A, Pilsner JR, Krawetz SA, Sergeyev O. Age-associated epigenetic changes in mammalian sperm: implications for offspring health and development. Hum Reprod Update 2022; 29:24-44. [PMID: 36066418 PMCID: PMC9825272 DOI: 10.1093/humupd/dmac033] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 08/05/2022] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Modern reproductive behavior in most developed countries is characterized by delayed parenthood. Older gametes are generally less fertile, accumulating and compounding the effects of varied environmental exposures that are modified by lifestyle factors. Clinicians are primarily concerned with advanced maternal age, while the influence of paternal age on fertility, early development and offspring health remains underappreciated. There is a growing trend to use assisted reproductive technologies for couples of advanced reproductive age. Thus, the number of children born from older gametes is increasing. OBJECTIVE AND RATIONALE We review studies reporting age-associated epigenetic changes in mammals and humans in sperm, including DNA methylation, histone modifications and non-coding RNAs. The interplay between environment, fertility, ART and age-related epigenetic signatures is explored. We focus on the association of sperm epigenetics on epigenetic and phenotype events in embryos and offspring. SEARCH METHODS Peer-reviewed original and review articles over the last two decades were selected using PubMed and the Web of Science for this narrative review. Searches were performed by adopting the two groups of main terms. The first group included 'advanced paternal age', 'paternal age', 'postponed fatherhood', 'late fatherhood', 'old fatherhood' and the second group included 'sperm epigenetics', 'sperm', 'semen', 'epigenetic', 'inheritance', 'DNA methylation', 'chromatin', 'non-coding RNA', 'assisted reproduction', 'epigenetic clock'. OUTCOMES Age is a powerful factor in humans and rodent models associated with increased de novo mutations and a modified sperm epigenome. Age affects all known epigenetic mechanisms, including DNA methylation, histone modifications and profiles of small non-coding (snc)RNA. While DNA methylation is the most investigated, there is a controversy about the direction of age-dependent changes in differentially hypo- or hypermethylated regions with advanced age. Successful development of the human sperm epigenetic clock based on cross-sectional data and four different methods for DNA methylation analysis indicates that at least some CpG exhibit a linear relationship between methylation levels and age. Rodent studies show a significant overlap between genes regulated through age-dependent differentially methylated regions and genes targeted by age-dependent sncRNA. Both age-dependent epigenetic mechanisms target gene networks enriched for embryo developmental, neurodevelopmental, growth and metabolic pathways. Thus, age-dependent changes in the sperm epigenome cannot be described as a stochastic accumulation of random epimutations and may be linked with autism spectrum disorders. Chemical and lifestyle exposures and ART techniques may affect the epigenetic aging of sperm. Although most epigenetic modifications are erased in the early mammalian embryo, there is growing evidence that an altered offspring epigenome and phenotype is linked with advanced paternal age due to the father's sperm accumulating epigenetic changes with time. It has been hypothesized that age-induced changes in the sperm epigenome are profound, physiological and dynamic over years, yet stable over days and months, and likely irreversible. WIDER IMPLICATIONS This review raises a concern about delayed fatherhood and age-associated changes in the sperm epigenome that may compromise reproductive health of fathers and transfer altered epigenetic information to subsequent generations. Prospective studies using healthy males that consider confounders are recommended. We suggest a broader discussion focused on regulation of the father's age in natural and ART conceptions is needed. The professional community should be informed and should raise awareness in the population and when counseling older men.
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Affiliation(s)
| | | | - J Richard Pilsner
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Stephen A Krawetz
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA,Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Oleg Sergeyev
- Correspondence address. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory, House 1, Building 40, Room 322, Moscow 119992, Russia. E-mail: https://orcid.org/0000-0002-5745-3348
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Nie X, Munyoki SK, Sukhwani M, Schmid N, Missel A, Emery BR, DonorConnect, Stukenborg JB, Mayerhofer A, Orwig KE, Aston KI, Hotaling JM, Cairns BR, Guo J. Single-cell analysis of human testis aging and correlation with elevated body mass index. Dev Cell 2022; 57:1160-1176.e5. [PMID: 35504286 PMCID: PMC9090997 DOI: 10.1016/j.devcel.2022.04.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 03/12/2022] [Accepted: 04/04/2022] [Indexed: 01/15/2023]
Abstract
Aging men display reduced reproductive health; however, testis aging is poorly understood at the molecular and genomic levels. Here, we utilized single-cell RNA-seq to profile over 44,000 cells from both young and older men and examined age-related changes in germline development and in the testicular somatic cells. Age-related changes in spermatogonial stem cells appeared modest, whereas age-related dysregulation of spermatogenesis and somatic cells ranged from moderate to severe. Altered pathways included signaling and inflammation in multiple cell types, metabolic signaling in Sertoli cells, hedgehog signaling and testosterone production in Leydig cells, cell death and growth in testicular peritubular cells, and possible developmental regression in both Leydig and peritubular cells. Remarkably, the extent of dysregulation correlated with body mass index in older but not in younger men. Collectively, we reveal candidate molecular mechanisms underlying the complex testicular changes conferred by aging and their possible exacerbation by concurrent chronic conditions such as obesity.
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Affiliation(s)
- Xichen Nie
- Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Howard Hughes Medical Institute, Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Sarah K Munyoki
- Department of Obstetrics, Gynecology and Reproductive Sciences and Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Meena Sukhwani
- Department of Obstetrics, Gynecology and Reproductive Sciences and Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Nina Schmid
- Biomedical Center Munich (BMC), Cell Biology, Anatomy III, Ludwig-Maximilians-University (LMU), Grosshaderner Strasse 9, Planegg, Munich, 82152, Germany
| | - Annika Missel
- Biomedical Center Munich (BMC), Cell Biology, Anatomy III, Ludwig-Maximilians-University (LMU), Grosshaderner Strasse 9, Planegg, Munich, 82152, Germany
| | - Benjamin R Emery
- Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | | | - Jan-Bernd Stukenborg
- NORDFERTIL Research Laboratory Stockholm, Childhood Cancer Research Unit, Bioclinicum J9:30, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Solna 17164, Sweden
| | - Artur Mayerhofer
- Biomedical Center Munich (BMC), Cell Biology, Anatomy III, Ludwig-Maximilians-University (LMU), Grosshaderner Strasse 9, Planegg, Munich, 82152, Germany
| | - Kyle E Orwig
- Department of Obstetrics, Gynecology and Reproductive Sciences and Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Kenneth I Aston
- Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - James M Hotaling
- Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Bradley R Cairns
- Howard Hughes Medical Institute, Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Jingtao Guo
- Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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9
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Meyer-Ficca ML, Zwerdling AE, Swanson CA, Tucker AG, Lopez SA, Wandersee MK, Warner GM, Thompson KL, Chini CC, Chen H, Chini EN, Meyer RG. Low NAD + Levels Are Associated With a Decline of Spermatogenesis in Transgenic ANDY and Aging Mice. Front Endocrinol (Lausanne) 2022; 13:896356. [PMID: 35600581 PMCID: PMC9120959 DOI: 10.3389/fendo.2022.896356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 03/30/2022] [Indexed: 02/05/2023] Open
Abstract
Advanced paternal age has increasingly been recognized as a risk factor for male fertility and progeny health. While underlying causes are not well understood, aging is associated with a continuous decline of blood and tissue NAD+ levels, as well as a decline of testicular functions. The important basic question to what extent ageing-related NAD+ decline is functionally linked to decreased male fertility has been difficult to address due to the pleiotropic effects of aging, and the lack of a suitable animal model in which NAD+ levels can be lowered experimentally in chronologically young adult males. We therefore developed a transgenic mouse model of acquired niacin dependency (ANDY), in which NAD+ levels can be experimentally lowered using a niacin-deficient, chemically defined diet. Using ANDY mice, this report demonstrates for the first time that decreasing body-wide NAD+ levels in young adult mice, including in the testes, to levels that match or exceed the natural NAD+ decline observed in old mice, results in the disruption of spermatogenesis with small testis sizes and reduced sperm counts. ANDY mice are dependent on dietary vitamin B3 (niacin) for NAD+ synthesis, similar to humans. NAD+-deficiency the animals develop on a niacin-free diet is reversed by niacin supplementation. Providing niacin to NAD+-depleted ANDY mice fully rescued spermatogenesis and restored normal testis weight in the animals. The results suggest that NAD+ is important for proper spermatogenesis and that its declining levels during aging are functionally linked to declining spermatogenesis and male fertility. Functions of NAD+ in retinoic acid synthesis, which is an essential testicular signaling pathway regulating spermatogonial proliferation and differentiation, may offer a plausible mechanism for the hypospermatogenesis observed in NAD+-deficient mice.
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Affiliation(s)
- Mirella L. Meyer-Ficca
- School of Veterinary Medicine, Utah State University, Logan, UT, United States
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
- *Correspondence: Ralph G. Meyer, ; Mirella L. Meyer-Ficca,
| | - Alexie E. Zwerdling
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
| | - Corey A. Swanson
- School of Veterinary Medicine, Utah State University, Logan, UT, United States
| | - Abby G. Tucker
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
| | - Sierra A. Lopez
- School of Veterinary Medicine, Utah State University, Logan, UT, United States
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
| | - Miles K. Wandersee
- School of Veterinary Medicine, Utah State University, Logan, UT, United States
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
| | - Gina M. Warner
- Signal Transduction and Molecular Nutrition Laboratory, Kogod Aging Center, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic College of Medicine, Rochester, MN, United States
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic, Jacksonville, FL, United States
| | - Katie L. Thompson
- Signal Transduction and Molecular Nutrition Laboratory, Kogod Aging Center, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic College of Medicine, Rochester, MN, United States
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic, Jacksonville, FL, United States
| | - Claudia C.S. Chini
- Signal Transduction and Molecular Nutrition Laboratory, Kogod Aging Center, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic College of Medicine, Rochester, MN, United States
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic, Jacksonville, FL, United States
| | - Haolin Chen
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Eduardo N. Chini
- Signal Transduction and Molecular Nutrition Laboratory, Kogod Aging Center, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic College of Medicine, Rochester, MN, United States
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic, Jacksonville, FL, United States
| | - Ralph G. Meyer
- School of Veterinary Medicine, Utah State University, Logan, UT, United States
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
- *Correspondence: Ralph G. Meyer, ; Mirella L. Meyer-Ficca,
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10
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Matzkin ME, Calandra RS, Rossi SP, Bartke A, Frungieri MB. Hallmarks of Testicular Aging: The Challenge of Anti-Inflammatory and Antioxidant Therapies Using Natural and/or Pharmacological Compounds to Improve the Physiopathological Status of the Aged Male Gonad. Cells 2021; 10:cells10113114. [PMID: 34831334 PMCID: PMC8619877 DOI: 10.3390/cells10113114] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/06/2021] [Accepted: 11/08/2021] [Indexed: 12/21/2022] Open
Abstract
The evolutionary theory of aging supports a trade-off relationship between reproduction and aging. Aging of the male reproductive system primarily affects the testes, leading to a decrease in the levels of sexual hormones, alterations in sperm quality and production, and a decline in fertility that does not necessarily involve a complete cessation of spermatogenesis. Inflammation, oxidation, and apoptosis are events considered as predictors of pathogenesis and the development of age-related diseases that are frequently observed in aged testes. Although the molecular mechanisms are still poorly understood, accumulating evidence points toward pro-inflammatory molecules and reactive oxygen species as primary contributing factors for testicular aging. However, the real impact of aging-related testicular alterations on fertility, reproductive health, and life span is far from being fully revealed. This work discusses the current knowledge on the impact of aging in the testis, particularly of aging-related dysregulated inflammation and oxidative damage on the functioning of its different cell populations. More interestingly, this review covers the potential benefits of anti-aging interventions and therapies using either pharmacological compounds (such as non-selective non-steroidal anti-inflammatory medication) or more natural alternatives (such as various nutraceuticals or even probiotics) that exhibit anti-inflammatory, antioxidant, and anti-apoptotic properties. Some of these are currently being investigated or are already in clinical use to delay or prevent testicular aging.
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Affiliation(s)
- María Eugenia Matzkin
- Instituto de Biología y Medicina Experimental, CONICET, Ciudad de Buenos Aires C1428ADN, Argentina; (R.S.C.); (S.P.R.); (M.B.F.)
- Departamento de Bioquímica Humana, Cátedra I, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires C1121ABG, Argentina
- Correspondence: ; Tel.: +54-114783-2869 (ext. 1209)
| | - Ricardo Saúl Calandra
- Instituto de Biología y Medicina Experimental, CONICET, Ciudad de Buenos Aires C1428ADN, Argentina; (R.S.C.); (S.P.R.); (M.B.F.)
| | - Soledad Paola Rossi
- Instituto de Biología y Medicina Experimental, CONICET, Ciudad de Buenos Aires C1428ADN, Argentina; (R.S.C.); (S.P.R.); (M.B.F.)
- Departamento de Bioquímica Humana, Cátedra I, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires C1121ABG, Argentina
| | - Andrzej Bartke
- Geriatrics Research, Department of Internal Medicine, School of Medicine, Southern Illinois University, Springfield, IL 62794, USA;
| | - Mónica Beatriz Frungieri
- Instituto de Biología y Medicina Experimental, CONICET, Ciudad de Buenos Aires C1428ADN, Argentina; (R.S.C.); (S.P.R.); (M.B.F.)
- Cátedra de Química, Ciclo Básico Común, Universidad de Buenos Aires, Ciudad de Buenos Aires C1405CAE, Argentina
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11
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Stöckl JB, Schmid N, Flenkenthaler F, Drummer C, Behr R, Mayerhofer A, Arnold GJ, Fröhlich T. Age-Related Alterations in the Testicular Proteome of a Non-Human Primate. Cells 2021; 10:cells10061306. [PMID: 34074003 PMCID: PMC8225046 DOI: 10.3390/cells10061306] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/17/2021] [Accepted: 05/22/2021] [Indexed: 02/06/2023] Open
Abstract
Aging of human testis and associated cellular changes is difficult to assess. Therefore, we used a translational, non-human primate model to get insights into underlying cellular and biochemical processes. Using proteomics and immunohistochemistry, we analyzed testicular tissue of young (age 2 to 3) and old (age 10 to 12) common marmosets (Callithrix jacchus). Using a mass spectrometry-based proteomics approach, we identified 63,124 peptides, which could be assigned to 5924 proteins. Among them, we found proteins specific for germ cells and somatic cells, such as Leydig and Sertoli cells. Quantitative analysis showed 31 differentially abundant proteins, of which 29 proteins were more abundant in older animals. An increased abundance of anti-proliferative proteins, among them CDKN2A, indicate reduced cell proliferation in old testes. Additionally, an increased abundance of several small leucine rich repeat proteoglycans and other extracellular matrix proteins was observed, which may be related to impaired cell migration and fibrotic events. Furthermore, an increased abundance of proteins with inhibitory roles in smooth muscle cell contraction like CNN1 indicates functional alterations in testicular peritubular cells and may mirror a reduced capacity of these cells to contract in old testes.
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Affiliation(s)
- Jan B. Stöckl
- Laboratory for Functional Genome Analysis LAFUGA, Gene Center, LMU München, 81377 München, Germany; (J.B.S.); (F.F.)
| | - Nina Schmid
- Biomedical Center (BMC), Anatomy III–Cell Biology, Medical Faculty, LMU München, 82152 Martinsried, Germany; (N.S.); (A.M.)
| | - Florian Flenkenthaler
- Laboratory for Functional Genome Analysis LAFUGA, Gene Center, LMU München, 81377 München, Germany; (J.B.S.); (F.F.)
| | - Charis Drummer
- Platform Degenerative Diseases, German Primate Center, Leibniz Institute for Primate Research, 37077 Göttingen, Germany; (C.D.); (R.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, 37077 Göttingen, Germany
| | - Rüdiger Behr
- Platform Degenerative Diseases, German Primate Center, Leibniz Institute for Primate Research, 37077 Göttingen, Germany; (C.D.); (R.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, 37077 Göttingen, Germany
| | - Artur Mayerhofer
- Biomedical Center (BMC), Anatomy III–Cell Biology, Medical Faculty, LMU München, 82152 Martinsried, Germany; (N.S.); (A.M.)
| | - Georg J. Arnold
- Laboratory for Functional Genome Analysis LAFUGA, Gene Center, LMU München, 81377 München, Germany; (J.B.S.); (F.F.)
- Correspondence: (G.J.A.); (T.F.)
| | - Thomas Fröhlich
- Laboratory for Functional Genome Analysis LAFUGA, Gene Center, LMU München, 81377 München, Germany; (J.B.S.); (F.F.)
- Correspondence: (G.J.A.); (T.F.)
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12
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Mularoni V, Esposito V, Di Persio S, Vicini E, Spadetta G, Berloco P, Fanelli F, Mezzullo M, Pagotto U, Pelusi C, Nielsen JE, Rajpert-De Meyts E, Jorgensen N, Jorgensen A, Boitani C. Age-related changes in human Leydig cell status. Hum Reprod 2021; 35:2663-2676. [PMID: 33094328 DOI: 10.1093/humrep/deaa271] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 08/31/2020] [Indexed: 12/29/2022] Open
Abstract
STUDY QUESTION What are the consequences of ageing on human Leydig cell number and hormonal function? SUMMARY ANSWER Leydig cell number significantly decreases in parallel with INSL3 expression and Sertoli cell number in aged men, yet the in vitro Leydig cell androgenic potential does not appear to be compromised by advancing age. WHAT IS KNOWN ALREADY There is extensive evidence that ageing is accompanied by decline in serum testosterone levels, a general involution of testis morphology and reduced spermatogenic function. A few studies have previously addressed single features of the human aged testis phenotype one at a time, but mostly in tissue from patients with prostate cancer. STUDY DESIGN, SIZE, DURATION This comprehensive study examined testis morphology, Leydig cell and Sertoli cell number, steroidogenic enzyme expression, INSL3 expression and androgen secretion by testicular fragments in vitro. The majority of these endpoints were concomitantly evaluated in the same individuals that all displayed complete spermatogenesis. PARTICIPANTS/MATERIALS, SETTING, METHODS Testis biopsies were obtained from 15 heart beating organ donors (age range: 19-85 years) and 24 patients (age range: 19-45 years) with complete spermatogenesis. Leydig cells and Sertoli cells were counted following identification by immunohistochemical staining of specific cell markers. Gene expression analysis of INSL3 and steroidogenic enzymes was carried out by qRT-PCR. Secretion of 17-OH-progesterone, dehydroepiandrosterone, androstenedione and testosterone by in vitro cultured testis fragments was measured by LC-MS/MS. All endpoints were analysed in relation to age. MAIN RESULTS AND THE ROLE OF CHANCE Increasing age was negatively associated with Leydig cell number (R = -0.49; P < 0.01) and concomitantly with the Sertoli cell population size (R= -0.55; P < 0.001). A positive correlation (R = 0.57; P < 0.001) between Sertoli cell and Leydig cell numbers was detected at all ages, indicating that somatic cell attrition is a relevant cellular manifestation of human testis status during ageing. INSL3 mRNA expression (R= -0.52; P < 0.05) changed in parallel with Leydig cell number and age. Importantly, steroidogenic capacity of Leydig cells in cultured testis tissue fragments from young and old donors did not differ. Consistently, age did not influence the mRNA expression of steroidogenic enzymes. The described changes in Leydig cell phenotype with ageing are strengthened by the fact that the different age-related effects were mostly evaluated in tissue from the same men. LIMITATIONS, REASONS FOR CAUTION In vitro androgen production analysis could not be correlated with in vivo hormone values of the organ donors. In addition, the number of samples was relatively small and there was scarce information about the concomitant presence of potential confounding variables. WIDER IMPLICATIONS OF THE FINDINGS This study provides a novel insight into the effects of ageing on human Leydig cell status. The correlation between Leydig cell number and Sertoli cell number at any age implies a connection between these two cell types, which may be of particular relevance in understanding male reproductive disorders in the elderly. However aged Leydig cells do not lose their in vitro ability to produce androgens. Our data have implications in the understanding of the physiological role and regulation of intratesticular sex steroid levels during the complex process of ageing in humans. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by grants from Prin 2010 and 2017. The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER N/A.
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Affiliation(s)
- Valentina Mularoni
- Section of Histology and Medical Embryology, Department of Anatomical, Histological, Forensic and Orthopedic Sciences, University of Rome "La Sapienza", 00161 Rome, Italy
| | - Valentina Esposito
- Section of Histology and Medical Embryology, Department of Anatomical, Histological, Forensic and Orthopedic Sciences, University of Rome "La Sapienza", 00161 Rome, Italy
| | - Sara Di Persio
- Section of Histology and Medical Embryology, Department of Anatomical, Histological, Forensic and Orthopedic Sciences, University of Rome "La Sapienza", 00161 Rome, Italy
| | - Elena Vicini
- Section of Histology and Medical Embryology, Department of Anatomical, Histological, Forensic and Orthopedic Sciences, University of Rome "La Sapienza", 00161 Rome, Italy
| | - Gustavo Spadetta
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, University of Rome "La Sapienza", 00161 Rome, Italy
| | - Pasquale Berloco
- Department of General and Specialistic Surgery "Paride Stefanini", University of Rome "La Sapienza", 00161 Rome, Italy
| | - Flaminia Fanelli
- Endocrinology and Diabetes Prevention and Care-Unit, Department of Medical and Surgical Sciences, Centre for Applied Biomedical Research, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy
| | - Marco Mezzullo
- Endocrinology and Diabetes Prevention and Care-Unit, Department of Medical and Surgical Sciences, Centre for Applied Biomedical Research, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy
| | - Uberto Pagotto
- Endocrinology and Diabetes Prevention and Care-Unit, Department of Medical and Surgical Sciences, Centre for Applied Biomedical Research, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy
| | - Carla Pelusi
- Endocrinology and Diabetes Prevention and Care-Unit, Department of Medical and Surgical Sciences, Centre for Applied Biomedical Research, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy
| | - John E Nielsen
- Department of Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet 2100, Denmark, Copenhagen
| | - Ewa Rajpert-De Meyts
- Department of Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet 2100, Denmark, Copenhagen
| | - Niels Jorgensen
- Department of Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet 2100, Denmark, Copenhagen
| | - Anne Jorgensen
- Department of Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet 2100, Denmark, Copenhagen
| | - Carla Boitani
- Section of Histology and Medical Embryology, Department of Anatomical, Histological, Forensic and Orthopedic Sciences, University of Rome "La Sapienza", 00161 Rome, Italy
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13
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Cafe SL, Nixon B, Ecroyd H, Martin JH, Skerrett-Byrne DA, Bromfield EG. Proteostasis in the Male and Female Germline: A New Outlook on the Maintenance of Reproductive Health. Front Cell Dev Biol 2021; 9:660626. [PMID: 33937261 PMCID: PMC8085359 DOI: 10.3389/fcell.2021.660626] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/22/2021] [Indexed: 01/07/2023] Open
Abstract
For fully differentiated, long lived cells the maintenance of protein homeostasis (proteostasis) becomes a crucial determinant of cellular function and viability. Neurons are the most well-known example of this phenomenon where the majority of these cells must survive the entire course of life. However, male and female germ cells are also uniquely dependent on the maintenance of proteostasis to achieve successful fertilization. Oocytes, also long-lived cells, are subjected to prolonged periods of arrest and are largely reliant on the translation of stored mRNAs, accumulated during the growth period, to support meiotic maturation and subsequent embryogenesis. Conversely, sperm cells, while relatively ephemeral, are completely reliant on proteostasis due to the absence of both transcription and translation. Despite these remarkable, cell-specific features there has been little focus on understanding protein homeostasis in reproductive cells and how/whether proteostasis is "reset" during embryogenesis. Here, we seek to capture the momentum of this growing field by highlighting novel findings regarding germline proteostasis and how this knowledge can be used to promote reproductive health. In this review we capture proteostasis in the context of both somatic cell and germline aging and discuss the influence of oxidative stress on protein function. In particular, we highlight the contributions of proteostasis changes to oocyte aging and encourage a focus in this area that may complement the extensive analyses of DNA damage and aneuploidy that have long occupied the oocyte aging field. Moreover, we discuss the influence of common non-enzymatic protein modifications on the stability of proteins in the male germline, how these changes affect sperm function, and how they may be prevented to preserve fertility. Through this review we aim to bring to light a new trajectory for our field and highlight the potential to harness the germ cell's natural proteostasis mechanisms to improve reproductive health. This manuscript will be of interest to those in the fields of proteostasis, aging, male and female gamete reproductive biology, embryogenesis, and life course health.
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Affiliation(s)
- Shenae L. Cafe
- Priority Research Centre for Reproductive Science, Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
| | - Brett Nixon
- Priority Research Centre for Reproductive Science, Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
| | - Heath Ecroyd
- Molecular Horizons, School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Jacinta H. Martin
- Department of Human Genetics, McGill University Health Centre Research Institute, Montreal, QC, Canada
| | - David A. Skerrett-Byrne
- Priority Research Centre for Reproductive Science, Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
| | - Elizabeth G. Bromfield
- Priority Research Centre for Reproductive Science, Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
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14
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Salas-Huetos A, Tüttelmann F, Wyrwoll MJ, Kliesch S, Lopes AM, Goncalves J, Boyden SE, Wöste M, Hotaling JM, Nagirnaja L, Conrad DF, Carrell DT, Aston KI. Disruption of human meiotic telomere complex genes TERB1, TERB2 and MAJIN in men with non-obstructive azoospermia. Hum Genet 2020; 140:217-227. [PMID: 33211200 DOI: 10.1007/s00439-020-02236-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/03/2020] [Indexed: 12/14/2022]
Abstract
Non-obstructive azoospermia (NOA), the lack of spermatozoa in semen due to impaired spermatogenesis affects nearly 1% of men. In about half of cases, an underlying cause for NOA cannot be identified. This study aimed to identify novel variants associated with idiopathic NOA. We identified a nonconsanguineous family in which multiple sons displayed the NOA phenotype. We performed whole-exome sequencing in three affected brothers with NOA, their two unaffected brothers and their father, and identified compound heterozygous frameshift variants (one novel and one extremely rare) in Telomere Repeat Binding Bouquet Formation Protein 2 (TERB2) that segregated perfectly with NOA. TERB2 interacts with TERB1 and Membrane Anchored Junction Protein (MAJIN) to form the tripartite meiotic telomere complex (MTC), which has been shown in mouse models to be necessary for the completion of meiosis and both male and female fertility. Given our novel findings of TERB2 variants in NOA men, along with the integral role of the three MTC proteins in spermatogenesis, we subsequently explored exome sequence data from 1495 NOA men to investigate the role of MTC gene variants in spermatogenic impairment. Remarkably, we identified two NOA patients with likely damaging rare homozygous stop and missense variants in TERB1 and one NOA patient with a rare homozygous missense variant in MAJIN. Available testis histology data from three of the NOA patients indicate germ cell maturation arrest, consistent with mouse phenotypes. These findings suggest that variants in MTC genes may be an important cause of NOA in both consanguineous and outbred populations.
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Affiliation(s)
- Albert Salas-Huetos
- Andrology and IVF Laboratory, Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT, 84108, USA
| | - Frank Tüttelmann
- Institute of Reproductive Genetics, University of Münster, 48149, Münster, Germany
| | - Margot J Wyrwoll
- Institute of Reproductive Genetics, University of Münster, 48149, Münster, Germany.,Centre of Reproductive Medicine and Andrology, Department of Clinical and Surgical Andrology, University Hospital Münster, 48149, Münster, Germany
| | - Sabine Kliesch
- Centre of Reproductive Medicine and Andrology, Department of Clinical and Surgical Andrology, University Hospital Münster, 48149, Münster, Germany
| | - Alexandra M Lopes
- i3S-Instituto de Investigação e Inovação em Saúde, University of Porto, 4200-135, Porto, Portugal.,IPATIMUP-Instituto de Patologia e Imunologia Molecular da Universidade do Porto, 4200-135, Porto, Portugal
| | - João Goncalves
- Departamento de Genética Humana, Instituto Nacional de Saúde Dr Ricardo Jorge, 1649-016, Lisbon, Portugal.,ToxOmics-Centro de Toxicogenómica e Saúde Humana, Nova Medical School, 1169-056, Lisbon, Portugal
| | - Steven E Boyden
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112, USA.,Utah Center for Genetic Discovery, University of Utah School of Medicine, Salt Lake City, UT, 84112, USA
| | - Marius Wöste
- Institute of Medical Informatics, University of Münster, 48149, Munster, Germany
| | - James M Hotaling
- Andrology and IVF Laboratory, Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT, 84108, USA.,Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT, 84108, USA
| | | | - Liina Nagirnaja
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, 97006, USA
| | - Donald F Conrad
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, 97006, USA.,Department of Genetics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Douglas T Carrell
- Andrology and IVF Laboratory, Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT, 84108, USA.,Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112, USA
| | - Kenneth I Aston
- Andrology and IVF Laboratory, Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT, 84108, USA.
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15
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Laurentino S, Cremers J, Horsthemke B, Tüttelmann F, Czeloth K, Zitzmann M, Pohl E, Rahmann S, Schröder C, Berres S, Redmann K, Krallmann C, Schlatt S, Kliesch S, Gromoll J. A germ cell-specific ageing pattern in otherwise healthy men. Aging Cell 2020; 19:e13242. [PMID: 32951333 PMCID: PMC7576283 DOI: 10.1111/acel.13242] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 08/06/2020] [Accepted: 08/24/2020] [Indexed: 12/22/2022] Open
Abstract
Life‐long sperm production leads to the assumption that male fecundity remains unchanged throughout life. However, recently it was shown that paternal age has profound consequences for male fertility and offspring health. Paternal age effects are caused by an accumulation of germ cell mutations over time, causing severe congenital diseases. Apart from these well‐described cases, molecular patterns of ageing in germ cells and their impact on DNA integrity have not been studied in detail. In this study, we aimed to assess the effects of ‘pure’ ageing on male reproductive health and germ cell quality. We assembled a cohort of 198 healthy men (18–84 years) for which end points such as semen and hormone profiles, sexual health and well‐being, and sperm DNA parameters were evaluated. Sperm production and hormonal profiles were maintained at physiological levels over a period of six decades. In contrast, we identified a germ cell‐specific ageing pattern characterized by a steady increase of telomere length in sperm and a sharp increase in sperm DNA instability, particularly after the sixth decade. Importantly, we found sperm DNA methylation changes in 236 regions, mostly nearby genes associated with neuronal development. By in silico analysis, we found that 10 of these regions are located in loci which can potentially escape the first wave of genome‐wide demethylation after fertilization. In conclusion, human male germ cells present a unique germline‐specific ageing process, which likely results in diminished fecundity in elderly men and poorer health prognosis for their offspring.
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Affiliation(s)
- Sandra Laurentino
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | | | - Bernhard Horsthemke
- Institute of Human Genetics University of Duisburg‐EssenUniversity Hospital Essen Essen Germany
| | - Frank Tüttelmann
- Institute of Reproductive Genetics University of Münster Münster Germany
| | - Karen Czeloth
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Michael Zitzmann
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Eva Pohl
- Institute of Human Genetics University of Münster Münster Germany
| | - Sven Rahmann
- Genome Informatics University of Duisburg‐EssenUniversity Hospital Essen Essen Germany
| | - Christopher Schröder
- Genome Informatics University of Duisburg‐EssenUniversity Hospital Essen Essen Germany
| | - Sven Berres
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Klaus Redmann
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Claudia Krallmann
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Stefan Schlatt
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Sabine Kliesch
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
| | - Jörg Gromoll
- Centre of Reproductive Medicine and Andrology University of Münster Münster Germany
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16
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Portela JMD, Heckmann L, Wistuba J, Sansone A, van Pelt AMM, Kliesch S, Schlatt S, Neuhaus N. Development and Disease-Dependent Dynamics of Spermatogonial Subpopulations in Human Testicular Tissues. J Clin Med 2020; 9:jcm9010224. [PMID: 31947706 PMCID: PMC7019285 DOI: 10.3390/jcm9010224] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 01/03/2020] [Accepted: 01/10/2020] [Indexed: 12/22/2022] Open
Abstract
Cancer therapy and conditioning treatments of non-malignant diseases affect spermatogonial function and may lead to male infertility. Data on the molecular properties of spermatogonia and the influence of disease and/or treatment on spermatogonial subpopulations remain limited. Here, we assessed if the density and percentage of spermatogonial subpopulation changes during development (n = 13) and due to disease and/or treatment (n = 18) in tissues stored in fertility preservation programs, using markers for spermatogonia (MAGEA4), undifferentiated spermatogonia (UTF1), proliferation (PCNA), and global DNA methylation (5mC). Throughout normal prepubertal testicular development, only the density of 5mC-positive spermatogonia significantly increased with age. In comparison, patients affected by disease and/or treatment showed a reduced density of UTF1-, PCNA- and 5mC-positive spermatogonia, whereas the percentage of spermatogonial subpopulations remained unchanged. As an exception, sickle cell disease patients treated with hydroxyurea displayed a reduction in both density and percentage of 5mC- positive spermatogonia. Our results demonstrate that, in general, a reduction in spermatogonial density does not alter the percentages of undifferentiated and proliferating spermatogonia, nor the establishment of global methylation. However, in sickle cell disease patients’, establishment of spermatogonial DNA methylation is impaired, which may be of importance for the potential use of this tissues in fertility preservation programs.
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Affiliation(s)
- Joana M. D. Portela
- Center of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany; (J.M.D.P.); (L.H.); (J.W.); (A.S.); (S.S.)
- Center for Reproductive Medicine, Amsterdam Research Institute Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
| | - Laura Heckmann
- Center of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany; (J.M.D.P.); (L.H.); (J.W.); (A.S.); (S.S.)
| | - Joachim Wistuba
- Center of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany; (J.M.D.P.); (L.H.); (J.W.); (A.S.); (S.S.)
| | - Andrea Sansone
- Center of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany; (J.M.D.P.); (L.H.); (J.W.); (A.S.); (S.S.)
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy
| | - Ans M. M. van Pelt
- Center for Reproductive Medicine, Amsterdam Research Institute Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
| | - Sabine Kliesch
- Center of Reproductive Medicine and Andrology, Department of Clinical and Surgical Andrology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany;
| | - Stefan Schlatt
- Center of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany; (J.M.D.P.); (L.H.); (J.W.); (A.S.); (S.S.)
| | - Nina Neuhaus
- Center of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, Albert-Schweitzer-Campus 1, Building D11, 48149 Münster, Germany; (J.M.D.P.); (L.H.); (J.W.); (A.S.); (S.S.)
- Correspondence:
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17
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Schmid N, Flenkenthaler F, Stöckl JB, Dietrich KG, Köhn FM, Schwarzer JU, Kunz L, Luckner M, Wanner G, Arnold GJ, Fröhlich T, Mayerhofer A. Insights into replicative senescence of human testicular peritubular cells. Sci Rep 2019; 9:15052. [PMID: 31636313 PMCID: PMC6803627 DOI: 10.1038/s41598-019-51380-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 09/27/2019] [Indexed: 01/10/2023] Open
Abstract
There is evidence for an age-related decline in male reproductive functions, yet how the human testis may age is not understood. Human testicular peritubular cells (HTPCs) transport sperm, contribute to the spermatogonial stem cell (SSC) niche and immune surveillance, and can be isolated and studied in vitro. Consequences of replicative senescence of HTPCs were evaluated to gain partial insights into human testicular aging. To this end, early and advanced HTPC passages, in which replicative senescence was indicated by increased cell size, altered nuclear morphology, enhanced β-galactosidase activity, telomere attrition and reduced mitochondrial DNA (mtDNA), were compared. These alterations are typical for senescent cells, in general. To examine HTPC-specific changes, focused ion beam scanning electron microscopy (FIB/SEM) tomography was employed, which revealed a reduced mitochondrial network and an increased lysosome population. The results coincide with the data of a parallel proteomic analysis and indicate deranged proteostasis. The mRNA levels of typical contractility markers and growth factors, important for the SSC niche, were not significantly altered. A secretome analysis identified, however, elevated levels of macrophage migration inhibitory factor (MIF) and dipeptidyl peptidase 4 (DPP4), which may play a role in spermatogenesis. Testicular DPP4 may further represent a possible drug target.
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Affiliation(s)
- Nina Schmid
- LMU München, Biomedical Center (BMC), Anatomy III - Cell Biology, 82152, Planegg-Martinsried, Germany
| | - Florian Flenkenthaler
- LMU München, Gene Center, Laboratory for Functional Genome Analysis (LAFUGA), 81377 München, Germany
| | - Jan B Stöckl
- LMU München, Gene Center, Laboratory for Functional Genome Analysis (LAFUGA), 81377 München, Germany
| | - Kim-Gwendolyn Dietrich
- LMU München, Biomedical Center (BMC), Anatomy III - Cell Biology, 82152, Planegg-Martinsried, Germany
| | | | | | - Lars Kunz
- LMU München, Department Biology II, Division of Neurobiology, 82152, Planegg-Martinsried, Germany
| | - Manja Luckner
- LMU München, Department Biology I, Ultrastructural Research, 82152, Planegg-Martinsried, Germany
| | - Gerhard Wanner
- LMU München, Department Biology I, Ultrastructural Research, 82152, Planegg-Martinsried, Germany
| | - Georg J Arnold
- LMU München, Gene Center, Laboratory for Functional Genome Analysis (LAFUGA), 81377 München, Germany
| | - Thomas Fröhlich
- LMU München, Gene Center, Laboratory for Functional Genome Analysis (LAFUGA), 81377 München, Germany
| | - Artur Mayerhofer
- LMU München, Biomedical Center (BMC), Anatomy III - Cell Biology, 82152, Planegg-Martinsried, Germany.
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