About
39
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Introduction
Additional affiliations
November 2016 - December 2017
January 2018 - present
University hospital Münster
Position
- PostDoc Position
Education
November 2013 - October 2016
January 2012 - October 2013
October 2007 - January 2012
Publications
Publications (39)
Male germ cells share a common origin across animal species, therefore they likely retain a conserved genetic program that defines their cellular identity. However, the unique evolutionary dynamics of male germ cells coupled with their widespread leaky transcription pose significant obstacles to the identification of the core spermatogenic program....
Male germ cells share a common origin across animal species, therefore they likely retain a conserved genetic program that defines their cellular identity. However, the unique evolutionary dynamics of male germ cells coupled with their widespread leaky transcription pose significant obstacles to the identification of the core spermatogenic program....
piRNAs are crucial for transposon silencing, germ cell maturation, and fertility in male mice. Here, we report on the genetic landscape of piRNA dysfunction in humans and present 39 infertile men carrying biallelic variants in 14 different piRNA pathway genes, including PIWIL1, GTSF1, GPAT2, MAEL, TDRD1, and DDX4. In some affected men, the testicul...
Study question
What are the specific changes under gender affirming hormone therapy (GAHT) in the spermatogonial cell compartment in testicular tissues of transwomen?
Summary answer
GAHT has a negative effect on the most undifferentiated PIWIL4+ spermatogonia potentially leading to reduced chances for fertility preservation in transwomen.
What is...
Male germ cells share a common origin across animal species, therefore they likely retain a conserved genetic program that defines their cellular identity. However, the unique evolutionary dynamics of male germ cells coupled with their widespread leaky transcription pose significant obstacles to the identification of the core spermatogenic program....
Sperm production and function require the correct establishment of DNA methylation patterns in the germline. Here, we examined the genome-wide DNA methylation changes during human spermatogenesis and its alterations in disturbed spermatogenesis. We found that spermatogenesis is associated with remodeling of the methylome, comprising a global declin...
Male infertility and meiotic arrest have been linked to M1AP, the gene encoding meiosis I associated protein. In mice, M1AP interacts with the ZZS proteins SHOC1, TEX11, and SPO16, which promote DNA crossover formation during meiosis. To determine whether M1AP and ZZS proteins are involved in human male infertility by disrupting crossover formation...
STUDY QUESTION
Are there subgroups among patients with cryptozoospermia pointing to distinct etiologies?
SUMMARY ANSWER
We reveal two distinct subgroups of cryptozoospermic (Crypto) patients based on testicular tissue composition, testicular volume, and FSH levels.
WHAT IS KNOWN ALREADY
Cryptozoospermic patients present with a sperm concentration...
Piwi-interacting RNAs (piRNAs) are crucial for transposon silencing, germ cell maturation, and fertility in male mice. Here, we report on the genetic landscape of piRNA dysfunction in humans and present 39 infertile men carrying biallelic variants in 14 different piRNA pathway genes, including PIWIL1 , GTSF1 , GPAT2, MAEL, TDRD1 , and DDX4 as novel...
Sperm production and function require the correct establishment of DNA methylation patterns in the germline. Here, we examined the genome-wide DNA methylation changes during human spermatogenesis and its alterations in disturbed spermatogenesis. We found that spermatogenesis is associated with remodeling of the methylome, comprising a global-declin...
Background:
Infertility affects around 15% of all couples worldwide and is increasingly linked to variants in genes specifically expressed in the testis. Well-established causes of male infertility include pathogenic variants in the genes TEX11, TEX14, and TEX15, while few studies have recently reported variants in TEX13B, TEX13C, FAM9A (TEX39A),...
Background:
Clinical evidence has shown frequent hypogonadism following mitotane (MTT) treatment in male patients with adrenocortical carcinoma. This study aimed to evaluate the impact of MTT on male gonadal function.
Methods:
Morphological analysis of testes and testosterone assays were performed on adult CD1 MTT-treated and untreated mice. The...
The spermatogonial compartment maintains spermatogenesis throughout the reproductive lifespan. Single-cell RNA sequencing (scRNA-seq) has revealed the presence of several spermatogonial clusters characterized by specific molecular signatures. However, it is unknown whether the presence of such clusters can be confirmed in terms of protein expressio...
The family of WWC proteins is known to regulate cell proliferation and organ growth control via the Hippo signaling pathway. As WWC proteins share a similar domain structure and a common set of interacting proteins, they are supposed to fulfill compensatory functions in cells and tissues. While all three WWC family members WWC1, WWC2, and WWC3 are...
Non-obstructive azoospermia, the absence of sperm in the ejaculate due to disturbed spermatogenesis, represents the most severe form of male infertility. De novo microdeletions of the Y-chromosomal AZFa region are one of few well-established genetic causes for NOA and are routinely analysed in the diagnostic workup of affected men. So far, it is un...
The process of spermatogenesis—when germ cells differentiate into sperm—is tightly regulated, and misregulation in gene expression is likely to be involved in the physiopathology of male infertility. The testis is one of the most transcriptionally rich tissues; nevertheless, the specific gene expression changes occurring during spermatogenesis are...
The amount of single-cell RNA-sequencing (scRNA-seq) data produced in the field of human male reproduction has steadily increased. Transcriptional profiles of thousands of testicular cells have been generated covering the human neonatal, prepubertal, pubertal and adult period as well as different types of male infertility; the latter include non-ob...
Study question
Can cryptozoospermic patients be sub classified based on clinical parameters?
Summary answer
Cryptozoospermic patients can be subdivided in two subgroups based on the histological phenotype of their testicular tissues, testicular volume and FSH levels.
What is known already
Cryptozoospermia is a severe form of oligozoospermia in wh...
Cell differentiation processes are highly dependent on cell stage-specific gene expression, including timely production of alternatively spliced transcripts. One of the most transcriptionally rich tissues is the testis, where the process of spermatogenesis, or generation of male gametes, takes place. To date, germ cell-specific transcriptome dynami...
Despite the high incidence of male infertility, only 30% of infertile men receive a causative diagnosis. To explore the regulatory mechanisms governing human germ cell function in normal and impaired spermatogenesis (crypto), we performed single-cell RNA sequencing (>30,000 cells). We find major alterations in the crypto spermatogonial compartment...
Background
Several studies have reported an association between male infertility and aberrant sperm DNA methylation patterns, in particular in imprinted genes. In a recent investigation based on whole methylome and deep bisulfite sequencing, we have not found any evidence for such an association, but have demonstrated that somatic DNA contamination...
Study question
Do DNA methylation changes occur in testicular germ cells (TGCs) from patients with impaired spermatogenesis?
Summary answer
TGCs from men with cryptozoospermia exhibit altered DNA methylation levels at several genomic regions, many of which are associated with genes involved in spermatogenesis.
What is known already
In the last 15...
Mutations affecting the germline can result in infertility or the generation of germ cell tumors (GCT), highlighting the need to identify and characterize the genes controlling germ cell development. The RNA-binding protein and E3 ubiquitin ligase TRIM71 is essential for embryogenesis, and its expression has been reported in GCT and adult mouse tes...
Despite the high incidence of male infertility, about 70% of infertile men do not receive a causative diagnosis. To gain insights into the regulatory mechanisms governing human germ cell function in normal and impaired spermatogenesis (cryptozoospermic patients, crypto), we combined single cell RNA sequencing (>30.000 cells), proteome, and histomor...
Mutations affecting the germline can result in infertility or the generation of germ cell tumors (GCT), highlighting the need to identify and characterize the genes controlling the complex molecular network orchestrating germ cell development. TRIM71 is a stem cell-specific factor essential for embryogenesis, and its expression has been reported in...
Background
Glial cell line-derived neurotrophic factor (GDNF) is a soluble molecule crucial for the regulation of the spermatogonial stem cells (SSC) of the testis. The effects of GDNF on target cells have been extensively described, but mechanisms underlying GDNF regulation are currently under investigation. In the nervous system, GDNF expression...
Background:
In the past 15 years, numerous studies have described aberrant DNA methylation of imprinted genes (e.g. MEST and H19) in sperm of oligozoospermic men, but the prevalence and genomic extent of abnormal methylation patterns have remained unknown.
Results:
Using deep bisulfite sequencing (DBS), we screened swim-up sperm samples from 40...
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 kno...
Background
In the past 15 years, numerous studies have described aberrant DNA methylation of imprinted genes (e.g. MEST and H19 ) in sperm of infertile patients, but the prevalence and genomic extent of abnormal methylation patterns have remained unknown.
Results
Using deep bisulfite sequencing (DBS), we screened swim-up sperm samples from 40 norm...
Glial cell line‐derived neurotrophic factor (GDNF) and retinoic acid (RA) are two molecules crucial for the regulation of the spermatogonial compartment of the testis. During the cycle of the seminiferous epithelium, their relative concentration oscillates with lower GDNF levels in stages where RA levels are high. It has been recently shown that RA...
Background:
The most common sex chromosomal aneuploidy in males is Klinefelter syndrome, which is characterized by at least one supernumerary X chromosome. While these men have long been considered infertile, focal spermatogenesis can be observed in some patients, and sperm can be surgically retrieved and used for artificial reproductive technique...
The human spermatogonial compartment is essential for daily production of millions of sperm. Despite this crucial role, the molecular signature, kinetic behavior and regulation of human spermatogonia are poorly understood. Using human testis biopsies with normal spermatogenesis and studying marker protein expression, for the first time we identifie...
Table S1. List of the 4,090 Differentially Regulated Exons, from 1,735 Distinct Genes, between Spermatocytes and Spermatids, Related to Figure 1
Table S2. List of the 1,114 Differentially Regulated Alternative Splicing Events—Known Splicing Patterns—from 714 Distinct Genes, between Spermatocytes and Spermatids, Related to Figure 1
Global transcriptome reprogramming during spermatogenesis ensures timely expression of factors in each phase of male germ cell differentiation. Spermatocytes and spermatids require particularly extensive reprogramming of gene expression to switch from mitosis to meiosis and to support gamete morphogenesis. Here, we uncovered an extensive alternativ...
In all mammals, spermatogonia are defined as constituting the mitotic compartment of spermatogenesis including stem, undifferentiated and differentiating cell types, possessing distinct morphological and molecular characteristics. Even though the real nature of the spermatogonial stem cell and its regulation is still debated the general consensus h...