Biology subjects

Schorle, H.

Publications and source records attributed to Schorle, H..

17 recordsLinked to original sources

bioRxiv2026

XPO1 Inhibition by Selinexor Induces Nuclear p53 and p21 Accumulation, Cell-Cycle Arrest and Apoptosis in Testicular Germ Cell Tumors

Background: Testicular germ cell tumors (TGCTs) are the most common solid malignancies in young men. Despite high cure rates with cisplatin-based chemotherapy, resistance and long-term toxicities remain clinical challenges in TGCTs. Selinexor, an FDA-approved XPO1 inhibitor, has demonstrated anti-tumor activity in other cancers, but its potential in TGCTs remains unknown. Objective: We investigated the antitumor effects of selinexor in TGCT cell lines. Materials and methods: XPO1 RNA expression, protein abundance and localization were evaluated by immunohistochemistry in TGCT tissue microarrays and non-neoplastic testicular tissues, and by meta-analysis of publicly available gene-expression microarray datasets from normal testis, primary TGCT specimens as well as TGCT cell lines. Selinexor effects on cell viability, cell-cycle distribution and apoptosis were evaluated using XTT assay and flow cytometry. p53 and p21 expression and localization were analyzed by Western blotting and Immunofluorescence. Results: XPO1 expression was heterogeneous across normal testis, TGCT tissues and cell lines. Yet, selinexor reduced TGCT cell viability and induced G1 or G2/M cell-cycle arrest, apoptosis, increased total p53 and p21 protein levels, and their nuclear accumulation. Of note, control fibroblast exhibited limited sensitivity to selinexor. Discussion and conclusion: Our findings demonstrate that inhibition of XPO1 with selinexor might be potential therapeutic strategy for TGCTs.

cancer biology↗

bioRxiv2026

G-quadruplex targeting by CX-5461 as a novel therapeutic strategy in testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are highly curable malignancies; however, resistance to cisplatin-based therapy remains a critical clinical challenge. G-quadruplexes (G4s) are specific guanine rich, four-stranded DNA structures that are enriched at distinct genomic regions. Due to their stability, G4s can influence genome stability, gene expression, DNA replication as well as telomere maintenance. G4 stabilization by small molecules has been shown to have anticancer effects in several tumors but remains underexplored in TGCTs. Here, we systematically evaluated the effect of six different G4- ligands (CX-5461, CX-3543, BRACO19, PDS, CM03 and RHPS4) on TGCT cell lines and non-malignant fibroblasts. Among those G4 ligands, CX-5461 showed strongest cellular changes in TGCTs. We observed dose- and time-dependent G4 stabilization upon CX-5461 treatment in TGCT cells, accompanied by impaired RNA polymerase I-dependent transcription and induction of DNA double-strand breaks, whereas only minimal effects were observed in control fibroblasts. These effects led to the activation of p53 signaling, and consequently an upregulation of canonical p53 target genes, including CDKN1A, MDM2, PIDD1, GADD45A, ZMAT3, SESN1 and PPM1D, resulting in G2/M cell-cycle arrest and apoptosis. The presence of potential quadruplex forming sequences (PQSs) in the promoters or gene bodies of these genes suggests that G4 structures may contribute to the p53 transcriptional response. Collectively, these data demonstrate that CX-5461 appears as highly potent G4-ligand inducing p53-dependent molecular cascades leading to cell death in germ cell tumors. Unlike in many other tumors, p53 remains functionally intact in TGCTs, suggesting that CX-5461-mediated activation of the p53 pathway could be selectively targeted as a therapeutic strategy in TGCTs.

cancer biology↗

bioRxiv2026

PDE3A-SLFN12 Molecular Glues Target Multiple KIT D816V Cell Types in Preclinical Models of Mast Cell Malignancies

A drug discovery approach was used to specifically target malignant cells with KIT D816V mutation, which is the predominant disease-causing mutation in clonal mast cell malignancies. To this end, KIT D816V cells derived from induced pluripotent stem cells (iPS cells) of KIT D816V patients were employed to screen a library of FDA approved and experimental drugs for specific killing of KIT D816V cells. We discovered the novel compound LDC 3416, which targets multiple malignant KIT D816V cell types, including hematopoietic stem/progenitor cells and mast cells. Importantly, by exploring the LDC 3416 targeting profile, we identified the phosphodiesterase 3A-Schlafen 12 (PDE3A-SLFN12) molecular glue pathway as a novel approach for specific targeting of malignant KIT D816V cells. We found that the KIT D816V mutant protein leads to increased expression of PDE3A and SLFN12 and thus confers a selective molecular vulnerability to PDE3A-SLFN12 molecular glues. Primary malignant mast cells of KIT D816V patients with indolent and advanced systemic mastocytosis also exhibit increased expression of PDE3A and SLFN12. We extended our study to include additional PDE3A-SLFN12 molecular glues and demonstrate their synergistic action with KIT D816V selective tyrosine kinase inhibitors (TKIs) in killing KIT D816V cells. Furthermore, the PDE3A-SLFN12 molecular glues also target KIT D816V megakaryocytes, a cell type that has been underestimated in malignant mast cell pathophysiology and molecular targeting. The identified molecular glues, along with their synergy with TKIs and their simultaneous targeting of multiple KIT D816V cell types, open novel treatment options for KIT D816V mast cell malignancies and other KIT D816V associated diseases.

cancer biology↗

bioRxiv2026

Loss of perinuclear theca protein ACTRT2 causes subfertility and acrosome destabilization in mice

Actin-related protein T2 (ACTRT2) localizes to the perinuclear theca (PT) of male germ cells, yet its functional significance remains unclear. ACTRT2 is evolutionarily conserved and exhibits significant sequence similarity to other testis-specific actin-related proteins, with the highest conservation observed within the canonical actin core domain. We generated Actrt2-deficient mice which displayed male subfertility with pronounced acrosomal malformations originating during the Cap phase of acrosome biogenesis. Actrt2-deficient male mice showed reduced fertilization rate and poor blastocysts quality. Co-immunoprecipitation identified ACTRT2 interactions with PT proteins ACTRT1, ACTRT3, ACTL7A, ACTL9, PFN3, SPEM2 and CCIN while the interaction with CYLC1 was not detected. ACTRT2 overexpression in HEK293T cells altered cell morphology and F-actin distribution. Further, cytoskeletal regulator CFL1 was enriched in testis from Actrt2-deficient mice. We propose that ACTRT2 is a structural component of the PT stabilizing the acroplaxome during spermiogenesis and acrosome biogenesis by modulating actin dynamics. Finally, the high degree of sequence conservation and similarity with ACTRT1 and ACTRT3 together with their similar phenotypes when deleted, indicate that ACTRT2 shares a partial functional redundancy and compensatory capacity with other Arp proteins in testis. Taken together, these findings establish ACTRT2 as a structural regulator of sperm head architecture and male fertility in mice.

molecular biology↗

bioRxiv2026

Male mice heterozygous for Protamine-1 and Protamine-2 are infertile displaying sperm damage and retention of Protamine-2 precursors, transition proteins and histones.

BACKGROUNDDuring spermiogenesis, histones are exchanged by protamines (PRMs) in spermatids, which results in DNA hypercondensation and protection. Rodents and primates express two PRMs (PRM1 and PRM2) in a species-specific ratio. Maintaining this ratio is necessary for functional chromatin reorganization and alteration is associated with sub- or infertility in mice and humans. Prm1 and Prm2 deficient mice are infertile, while Prm1+/- males are subfertile showing a severely altered PRM ratio. Prm2+/- males are fertile and display a protamine ratio comparable to WT. OBJECTIVESHere, we addressed the question whether loss of one allele of Prm1 and one allele of Prm2 affects fertility. MATERIAL AND METHODSDouble heterozygous (dHET) mice lacking one allele of Prm1 and one allele of Prm2 were generated and analyzed RESULTSdHET males were infertile with sperm showing retention of histones and TNPs, high levels of PRM2 precursor and decreased levels of mature PRM2. In mature sperm the PRM ratio and the total PRM content was not altered. However, CMA3 staining revealed incomplete protamination and sperm nuclei appeared more rounded and slightly bigger, suggesting impaired DNA-hypercondensation. In dHET sperm, DNA degradation was apparent, but to a lower level compared to sperm from Prm1 and Prm2 deficient males. Increased 8-OHdG levels suggested oxidative stress in the epididymis of dHET mice. However, a fraction of dHET sperm were capable of fertilization, with embryonic development up to 8-cell stage. DISCUSSION AND CONCLUSIONThese results suggest, that male factor infertility might not be reliably detected by measuring PRM1/PRM2 ratio but rather by determining the level of protamination by e.g. CMA3 analysis and pre-PRM2 retention.

developmental biology↗

bioRxiv2025

Protamine expression in somatic cells condenses chromatin and disrupts transcription without altering DNA methylation

Protamines play a crucial role in nuclear condensation during spermiogenesis, a process that involves significant chromatin remodeling and the replacement of histones. While much research has focused on the function of protamines in sperm development and fertility, their effects in non-sperm cells remain largely unexplored. In this study, we investigated the impact of overexpressing murine and human protamine 1 and 2 (PRM1 and PRM2) on nuclear architecture, histone eviction, DNA methylation, and transcription in HEK293T cells and mesenchymal stromal cells (MSCs). Overexpression of protamines resulted in nuclear condensation; particularly PRM1 showed notable enrichment in nucleoli, and cells exhibited cell cycle abnormalities. Immunofluorescence staining indicated a significant reduction in specific histone modifications (H3K9me3, H3K4me1, and H3K27Ac) in response to protamine expression, especially in MSCs. Interestingly, despite these changes in nuclear organization, the methylome remained largely stable. However, expression of protamines significantly diminished transcription, particularly of the ribosomal genes, upon PRM1 expression. Our studies indicate that PRM1 and PRM2 condense distinct genomic regions in somatic cells, resulting in widespread silencing of gene expression.

cell biology↗

bioRxiv2025

Actin-related protein M1 (ARPM1) required for acrosome biogenesis and sperm function in mice

Actin-related proteins (Arps) are a superfamily of proteins which share sequence similarities with conventional actin and are involved in different cellular processes. Actin-related protein M1 (ARPM1) also known as actin-related protein T3 (ACTRT3) is a testis-enriched Arp which can be found in the perinuclear theca (PT) of murine round and elongating spermatids. ARPM1 forming a complex with Profilin 3 (PFN3) is lost in Pfn3-deficient sperm. We generated a mouse model deficient for Arpm1 and demonstrate that Arpm1-/- male mice are subfertile, with morphological aberrations of the acrosome. During spermiogenesis, defects become apparent in Cap phase of acrosome biogenesis when abnormal acrosomal granules are observed. Arpm1-deficiency causes deregulation of GM130 and TGN46 suggestive of defects in cis- and trans-Golgi trafficking required for acrosome development. Co-immunoprecipitation revealed that ARPM1 interacts with the PT-specific proteins ACTRT1, ACTRT2, ACTL7A and the sperm surface protein ZPBP, additionally to its already shown interaction with PFN3. We propose that ARPM1 acts as a structural component of the PT contributing to the cytoskeletal network connecting acrosome and nucleus. In addition, ARPM1 mediates the localization of ZPBP to enable fertilization and it tethers PFN3 to properly regulate Golgi-related acrosome development.

developmental biology↗

bioRxiv2024

An aberrant protamine ratio is associated with decreased H4ac levels in murine and human sperm

Protamine 2 (Prm2/PRM2), together with Protamine 1 (Prm1/PRM1), constitute the two protamines found in both murine and human sperm. During spermiogenesis in haploid male germ cells, chromatin undergoes significant condensation, a phase in which most histones are replaced by a species-specific ratio of these two protamines. Altered PRM1/PRM2 ratios are associated with subfertility and infertility in both male mice and men. Notably, during histone-to-protamine exchange a small fraction of histones remains (ranging from 1% to 15%) bound to DNA. The regulatory roles of these residual histones, governed by post-translational modifications (PTMs), play a pivotal role in spermatogenesis, particularly in chromatin remodeling and epigenetic regulation of genes during sperm differentiation or even in early embryogenesis. In this study, utilizing a Prm2-deficient mouse model and conducting an analysis of sperm samples from men exhibiting either normozoospermia or atypical spermiograms, we observed alterations in the methylation and acetylation profiles of histones H3 and H4. Subsequent in-depth analysis revealed that discrepancies in protamine ratios do not significantly influence the post-translational modifications (PTMs) of histones in testicular sperm. In epididymal sperm these altered protamine ratios are associated with a reduction in the acetylation levels of histone H4 (H4ac), a phenomenon consistent across both murine and human samples. In particular, H4K5ac and H4K12ac were identified as the two modifications that appear to decrease as a result of reduced Prm2/PRM2 levels. Our findings reveal that Protamine 2 is necessary for the maintenance of specific histone PTMs, such as acetylation, which is essential for proper spermatogenesis and particularly for chromatin remodeling.

molecular biology↗

bioRxiv2024

Protamine 2 Deficiency Results In Septin 12 Abnormalities

There is a well-established link between abnormal sperm chromatin states and poor motility, however, how these two processes are interdependent is unknown. Here, we identified a possible mechanistic insight by showing that Protamine 2, a nuclear DNA packaging protein in sperm, directly interacts with cytoskeletal protein Septin 12, which is associated with sperm motility. Septin 12 has several isoforms, and we show, that in the Prm2-/-sperm, the short one (Mw 36 kDa) is mislocalized, while two long isoforms (Mw 40 and 41 kDa) are unexpectedly lost in Prm2-/- sperm chromatin-bound protein fractions. Septin 12 co-immunoprecipitated with Protamine 2 in the testicular cell lysate of WT mice and with Lamin B1/B2/B3 in co-transfected HEK cells despite we did not observe changes in Lamin B2/B3 protein or SUN4 expression in Prm2-/-testes. Furthermore, the Prm2-/- sperm have on average a smaller sperm nucleus and aberrant acrosome biogenesis. In humans, patients with low sperm motility (asthenozoospermia) have imbalanced histone- protamine 1/2 ratio and modified levels of cytoskeletal proteins. We detected retained Septin 12 isoforms (Mw 40 and 41 kDa) in the sperm membrane, chromatin-bound and tubulin/mitochondria protein fractions, which was not true for healthy normozoospermic men. In conclusion, our findings expand the current knowledge regarding the connection between Protamine 2 and Septin 12 expression and localization, resulting in low sperm motility and morphological abnormalities.

cell biology↗

bioRxiv2022

Cylicins are a structural component of the sperm calyx being indispensable for male fertility in mice and human

Cylicins are testis-specific proteins, which are exclusively expressed during spermiogenesis. In mice and humans, two Cylicins, the gonosomal X-linked Cylicin 1 (Cylc1/CYLC1) and the autosomal Cylicin 2 (Cylc2/CYLC2) genes have been identified. Cylicins are cytoskeletal proteins with an overall positive charge due to lysine-rich repeats. While Cylicins have been localized in the acrosomal region of round spermatids, they resemble a major component of the calyx within the perinuclear theca at the posterior part of mature sperm nuclei. However, the role of Cylicins during spermiogenesis has not yet been investigated. Here, we applied CRISPR/Cas9-mediated gene-editing in zygotes to establish Cylc1- and Cylc2-deficient mouse lines as a model to study the function of these proteins. Cylc1 deficiency resulted in male subfertility, whereas Cylc2-/-, Cylc1-/y Cylc2+/-, and Cylc1-/y Cylc2-/- males were infertile. Phenotypical characterization revealed that loss of Cylicins prevents proper calyx assembly during spermiogenesis. This results in decreased epididymal sperm counts, impaired shedding of excess cytoplasm, and severe structural malformations, ultimately resulting in impaired sperm motility. Furthermore, exome sequencing identified an infertile man with a hemizygous variant in CYLC1 and a heterozygous variant in CYLC2, displaying morphological abnormalities of the sperm including the absence of the acrosome. Thus, our study highlights the relevance and importance of Cylicins for spermiogenic remodeling and male fertility in human and mouse, and provides the basis for further studies on unraveling the complex molecular interactions between perinuclear theca proteins required during spermiogenesis.

developmental biology↗

bioRxiv2022

Actl7b-deficiency leads to mislocalization of LC8 type dynein light chains and disruption of murine spermatogenesis

Actin-related proteins (Arp) are classified according to their similarity to actin and are involved in diverse cellular processes. ACTL7B is a testis-specific Arp and highly conserved in rodents and primates. ACTL7B is specifically expressed in round and elongating spermatids during spermiogenesis. Here, we have generated an Actl7b-null allele in mice to unravel the role of ACTL7B in sperm formation. Male mice homozygous for the Actl7b-null allele (Actl7b-/-) were infertile, while heterozygous males (Actl7b+/-) were fertile. Severe spermatid defects such as detached acrosomes, disrupted membranes and failed elongation of the axoneme start to appear at spermiogenesis step 9 in Actl7b-/- mice, finally resulting in spermatogenic arrest. Abnormal spermatids, were degraded. Co-immunoprecipitation experiments identified interaction between ACTL7B and the LC8 dynein light chains DYNLL1 and DYNLL2, which are first detected in step 9 spermatids and mislocalized when ACTL7B is absent. Our data unequivocally establishes that mutations in ACTL7B are directly related to male infertility, pressing for additional research in men. Summary statementIn this study, Actl7b-deficient mice were generated. Loss of Actl7b leads to spermatogenic arrest in mice. ACTL7B interacts in with DYNLL1/DYNLL2 and seems to function in spermatid cytoskeleton.

developmental biology↗

bioRxiv2021

Loss of Prm1 leads to defective chromatin protamination, impaired PRM2 processing, reduced sperm motility and subfertility in male mice

One of the key events during spermiogenesis is the hypercondensation of chromatin by substitution of the majority of histones by protamines. In humans and mice, protamine 1 (PRM1/Prm1) and protamine 2 (PRM2/Prm2), are expressed in a species-specific ratio. Using CRISPR-Cas9-mediated gene editing we generated Prm1-deficient mice and demonstrate, that Prm1+/- mice are subfertile while Prm1-/- are infertile. Prm1-deficiency was associated with higher levels of 8-OHdG, an indicator for reactive oxygen mediated DNA-damage. While Prm1+/- males displayed moderate increased levels of 8-OHdG virtually all sperm of Prm1-/- males displayed ROS mediated DNA damage. Consequently, DNA integrity was slightly hampered in Prm1+/-, while DNA was completely fragmented in Prm1-/- animals. Interestingly CMA3 staining which indicates protamine-free DNA revealed, that Prm1+/- sperm displayed high levels (93%), compared to Prm2+/- (29%) and WT (2%) sperm. This is not due to increased histone retention as demonstrated by mass spectrometry (MassSpec) of nuclear proteins in Prm1+/- sperm. Further analysis of the MassSpec data from sperm nuclear proteome revealed, that only one protein (RPL31) is significantly higher abundant in Prm1+/- compared to WT sperm. Comparison of the proteome from Prm1-/- and Prm2-/- to WT suggested, that there are a small number of proteins which differ in abundance. However, their function was not linked mechanistically to primary defects seen in Prm1-/- mice and rather represent a general stress response. Interestingly, using acid urea gels we found that sperm from Prm1+/- and Prm1-/- mice contain a high level of unprocessed, full-length PRM2. Prm2 is transcribed as a precursor protein which, upon binding to DNA is successively processed. Further, the overall ratio of PRM1:PRM2 is skewed from 1:2 in WT to 1:5 in Prm1+/- animals. Our results reveal that Prm1 is required for proper processing of PRM2 to produce the mature PRM2 which, together with Prm1 is able to hypercondense DNA. Hence, the species specific PRM1:PRM2 ratio has to be precisely controlled in order to retain full fertility.

developmental biology↗

bioRxiv2021

Loss of the cleaved-protamine 2 domain leads to incomplete histone-to-protamine exchange and infertility in mice

Protamines are unique sperm-specific proteins that package and protect paternal chromatin until fertilization. A subset of mammalian species expresses two protamines (PRM1 and PRM2), while in others PRM1 is sufficient for sperm chromatin packaging. Alterations of the species-specific ratio between PRM1 and PRM2 are associated with infertility. Unlike PRM1, PRM2 is generated as a precursor protein consisting of a highly conserved N-terminal domain, termed cleaved PRM2 (cP2), which is consecutively trimmed off during chromatin condensation. The carboxyterminal part, called mature PRM2 (mP2), interacts with DNA and together with PRM1, mediates chromatin-hypercondensation. The removal of the cP2 domain is believed to be imperative for proper chromatin condensation, yet, the role of cP2 is not yet understood. We generated mice lacking the cP2 domain while the mP2 is still expressed. We show that the cP2 domain is indispensable for complete sperm chromatin protamination and male mouse fertility. cP2 deficient sperm show incomplete PRM2 incorporation, resulting in a severely altered protamine ratio, retention of transition proteins and aberrant retention of the testis specific histone variant H2A.L.2. During epididymal transit, cP2 deficient sperm seem to undergo ROS mediated degradation leading to complete DNA fragmentation. The cP2 domain therefore seems to be a key aspect in the complex crosstalk between histones, transition proteins and protamines during sperm chromatin condensation. Overall, we present the first step towards understanding the role of the cP2 domain in paternal chromatin packaging and open up avenues for further research.

genetics↗

bioRxiv2021

TRIM71 deficiency causes germ cell loss during mouse embryogenesis and promotes human male infertility

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 GCT and adult mouse testes. To investigate the role of TRIM71 in mammalian germ cell embryonic development, we generated a germline-specific conditional Trim71 knockout mouse (cKO) using the early primordial germ cell (PGC) marker Nanos3 as a Cre-recombinase driver. cKO mice are infertile, with male mice displaying a Sertoli cell-only (SCO) phenotype, which in humans is defined as a specific subtype of non-obstructive azoospermia characterized by the absence of developing germ cells in the testes seminiferous tubules. Infertility originates during embryogenesis, as the SCO phenotype was already apparent in neonatal mice. The in vitro differentiation of mouse embryonic stem cells (ESCs) into PGC-like cells (PGCLCs) revealed reduced numbers of PGCLCs in Trim71-deficient cells. Furthermore, in vitro growth competition assays with wild type and CRISPR/Cas9-generated TRIM71 mutant NCCIT cells, a human GCT-derived cell line which we used as a surrogate model for proliferating PGCs, showed that TRIM71 promotes NCCIT cell proliferation and survival. Our data collectively suggest that germ cell loss in cKO mice results from combined defects during the specification and maintenance of PGCs prior to their sex determination in the genital ridges. Last, via exome sequencing analysis, we identified several TRIM71 variants in a cohort of infertile men, including a loss-of-function variant in a patient with SCO phenotype. Our work reveals for the first time an association of TRIM71 variants with human male infertility, and uncovers further developmental roles for TRIM71 in the generation and maintenance of germ cells during mouse embryogenesis.

developmental biology↗

bioRxiv2021

Induction of peri-implantation stage synthetic embryos using reprogramming paradigms in ESCs

Blastocyst-derived stem cell lines were shown to self-organize into embryo-like structures in 3D cell culture environments. Here, we provide evidence that synthetic embryo-like structures are generated solely based on transcription factor-mediated molecular reprogramming of embryonic stem cells in a simple 3D co-culture system. ESCs in these cultures self-organize into elongated, compartmentalized synthetic embryo-like structures over the course of reprogramming exhibiting anterior visceral endoderm formation and symmetry breaking. Single-cell RNA-Seq reveals transcriptional profiles resembling epiblast, visceral endoderm, and extraembryonic ectoderm of early murine embryos around E4.5-E5.5. Within the epiblast, compartment marker gene expression supports primordial germ cell specification. After transplantation, synthetic embryo-like structures implant in uteri and initiate the formation of decidual tissues. This system allows for fast and reproducible generation of synthetic embryo-like structures, providing further insights into synthetic embryology.

synthetic biology↗

bioRxiv2020

Prm2 deficiency triggers a Reactive Oxygen Species (ROS)-mediated destruction cascade during epididymal sperm maturation in mice

Protamines are the safeguards of the paternal sperm genome. They replace most of the histones during spermiogenesis, resulting in DNA hypercondensation, thereby protecting its genome from environmental noxa. Impaired protamination has been linked to male infertility in mice and humans in many studies. Apart from impaired DNA integrity, protamine-deficient human and murine sperm show multiple secondary effects, including decreased motility and aberrant head morphology. In this study, we use a Prm2-deficient mouse model in combination with label-free quantitative proteomics to decipher the underlying molecular processes of these effects. We show that loss of the sperms antioxidant capacity, indicated by downregulation of key proteins like SOD1 and PRDX5, ultimately initiates an oxidative stress-mediated destruction cascade during epididymal sperm maturation. This is confirmed by an increased level of 8-OHdG in epididymal sperm, a biomarker for oxidative stress-mediated DNA damage. Prm2-deficient testicular sperm are not affected and initiate the proper development of blastocyst stage preimplantation embryos in vitro upon intracytoplasmic sperm injection (ICSI) into oocytes. Our results provide new insight into the role of Prm2 and its downstream molecular effects on sperm function and present an important contribution to the investigation of new treatment regimens for infertile men with impaired protamination. Significance statementSexual reproduction requires the successful fertilization of female eggs by male sperm. The generation of functional sperm is a complex, multi-step differentiation process known as spermatogenesis that takes places in the male testis. One important step for physiological sperm function is the incorporation of small proteins, known as protamines into the DNA. Defects within this process are common causes of male infertility. However, the underlying molecular mechanisms still remain largely unknown, thus preventing targeted therapies. Here, we identify the molecular cascade being initiated in protamine-deficient murine sperm that ultimately impedes fertilization. Our findings have broad implications for the development of new treatment options for infertile men with faulty protamination that seek medical advice.

molecular biology↗

bioRxiv2019

Unique and redundant roles of SOX2 and SOX17 in regulating the germ cell tumour fate

Embryonal carcinomas (ECs) and seminomas are testicular germ cell tumours. ECs display expression of SOX2, while seminomas display expression of SOX17. In somatic differentiation, SOX17 drives endodermal cell fate. However, seminomas lack expression of endoderm markers, but show features of pluripotency. Here, we use ChIP-sequencing to report and compare the binding pattern of SOX17 in seminoma-like TCam-2 cells to SOX2 in EC-like 2102EP cells and SOX17 in somatic cells. In seminoma-like cells, SOX17 was detected at canonical (SOX2/OCT4), compressed (SOX17/OCT4) and other SOX family member motifs. SOX17 directly regulates TFAP2C, PRDM1 and PRDM14, thereby maintaining latent pluripotency and supressing somatic differentiation. In contrast, in somatic cells canonical motifs are not bound by SOX17. In sum only 11% of SOX17 binding sites overlap in seminoma-like and somatic cells. This illustrates that binding site choice is highly dynamic and cell type specific. Deletion of SOX17 in seminoma-like cells resulted in loss of pluripotency, marked by a reduction of OCT4 protein level and loss of alkaline phosphatase activity. Further, we found that in EC-like cells SOX2 regulates pluripotency-associated genes, predominantly by partnering with OCT4. In conclusion, SOX17 (in seminomas) functionally replaces SOX2 (in ECs) to maintain expression of the pluripotency cluster.

cancer biology↗