Anti-Müllerian hormone: A function beyond the Müllerian structures

The anti-Müllerian hormone (AMH) is a heterodimeric glycoprotein belonging to the TGFb superfamily implicated in human embryonic development. This hormone was first described as allowing regression of the epithelial embryonic Müllerian structures in males, which would otherwise differentiate into the uterus and fallopian tubes. It activates a signaling pathway mediated by two transmembrane receptors. Binding of AMH to its receptor induces morphological changes leading to the degeneration of Müllerian ducts. Recently, new data has shown the role played by this hormone on structures other than the genital tract. If testicular AMH expression decreases in humans over the course of a lifetime, synthesis may persist in other tissues in adulthood. The mechanisms underlying its production have been unveiled. The aim of this review is to describe the different pathways in which AMH has been identified and plays a pivotal role.

P–055 Methylation dynamics of the sperm epigenome after chemotherapy: a case study

Study question

What is the evolution of the sperm epigenome after chemotherapy in a patient with testicular cancer (TC)?

Summary answer

These new data on epigenetic recovery profil after TC are useful tools for counseling and reassuring these patients.

What is known already

An important issue for young men affected TC is how TC and its treatment will affect, transiently or permanently, their future reproductive health. The consequences of cancer treatment on the sperm epigenome during the recovery periods are topical issues of ascendant significance as epigenetic modifications to the paternal genome may have deleterious effects on the offspring.

Study design, size, duration

Here we report the epigenomic profiling of frozen sperm from a TC patient before and after the treatment at different time points (6, 9, 12 and 24 months) by using RRBS analysis (Reduced representation bisulfite sequencing method).

Participants/materials, setting, methods

A testicular tumor (testicular germ cell tumor) was diagnosed in a 30 years old patient. A cryopreservation of spermatozoa was proposed before treatment.Semen samples were obtained 2 times before treatment and 4 times after treatment (6, 9, 12 and 24 months following the initiation of treatment).

Main results and the role of chance

Upon collection, sampling after chemotherapy ranged from 0,6 to 4,2 million per sperm straw between 6 and 24 months after the treatment, always increasing.

In order to capture the direct effect of the treatment on the methylation changes, the DMR detection has been operated between pre-chemotherapy samples (pair-wise) and the time point of 6 months. Among the 179 hqDMRs, 74 are differentially methylated between the PreCT and PostCT6m samples (16 hyper- and 68 hypo-methylated) associated with 49 DMGs (15 hyper- and 34 hypo-methylated).

We further sub-clustered the 74 hqDMRs between PreCT and PostCT6m into 6 patterns, 3 hyper- and 3 hypo-methylated. Briefly, patterns P1 and P4 include hqDMRs that quickly get back to their pre-treatment methylation status just after 9th months onwards. Patterns P2 and P5 include hqDMRs that slowly get back to their pre-treatment methylation status between 12 and 24 months after treatment. Patterns P3 and P6 include hqDMRs that remain hyper- or hypo-methylated even after 24 months.

We have intersected the genes (DMGs) associated with the detected hqDMRs with those known to be important or expressed during embryogenesis. We thus detected that 7 hyper-methylated and 6 hypomethylated DMGs were involved (or expressed) during embryonic / fetal development.

Limitations, reasons for caution

This study involves a single patient. As the patient made no major changes in his personal way of life, we hypothesized that sperm parameter variations may be attributable to the BEP treatment.

Wider implications of the findings: The altered methylated status of those DMGs important for early development might modify their expression pattern and thus affect their function during key stages of embryogenesis leading to potential developmental disorders. It is important to notice that among the 110 DMGs none of them correspond to known imprinted genes.

Trial registration number

Not applicable

Granulosa cells provide elimination of apoptotic oocytes through unconventional autophagy-assisted phagocytosis

STUDY QUESTION

Do human granulosa cells (GCs) ingest and destroy apoptotic oocytes?

SUMMARY ANSWER

Somatic GCs ingest and destroy apoptotic oocytes and other apoptotic substrates through unconventional autophagy-assisted phagocytosis.

WHAT IS KNOWN ALREADY

Most (99%) ovarian germ cells undergo apoptosis through follicular atresia. The mode of cleaning of atretic follicles from the ovary is unclear. Ovarian GCs share striking similarities with testicular Sertoli cells with respect to their origin and function. Somatic Sertoli cells are responsible for the elimination of apoptotic spermatogenic cells through unconventional autophagy-assisted phagocytosis.

STUDY DESIGN, SIZE, DURATION

Human GCs were tested for the ability to ingest and destroy the apoptotic oocytes and other apoptotic substrates. A systemic study of the main phagocytosis steps has been performed at different time points after loading of apoptotic substrates into the GC.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Primary cultures of GC retrieved following controlled ovarian stimulation of five women for IVF/ICSI and a human granulosa KGN cell line were incubated with different apoptotic substrates: oocytes which underwent spontaneous apoptosis during the cultivation of immature germ cells for IVF/ICSI; apoptotic KGN cells; and apoptotic membranes from rat retinas. Cultured GC were analyzed for the presence of specific molecular markers characteristic of different steps of phagocytic and autophagy machineries by immunocytochemistry, confocal microscopy, transmission electron microscopy and western blotting, before and after loading with apoptotic substrates.

MAIN RESULTS AND THE ROLE OF CHANCE

Incubation of human GC with apoptotic substrates resulted in their translocation in cell cytoplasm, concomitant with activation of the phagocytosis receptor c-mer proto-oncogene tyrosine kinase MERTK (P < 0.001), clumping of motor molecule myosin II, recruitment of autophagy proteins: autophagy-related protein 5 (ATG5), autophagy-related protein 6 (Beclin1) and the rise of a membrane form of microtubule-associated protein 1 light chain 3 (LC3-II) protein. Ingestion of apoptotic substrates was accompanied by increased expression of the lysosomal protease Cathepsin D (P < 0.001), and a rise of lysosomes in the GCs, as assessed by different techniques. The level of autophagy adaptor, sequestosome 1/p62 (p62) protein remained unchanged.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The number of patients described here is limited. Also the dependence of phagocytosis on reproductive hormone status of patients should be analyzed.

WIDER IMPLICATIONS OF THE FINDINGS

Removal of apoptotic oocytes by surrounding GC seems likely to be a physiological mechanism involved in follicular atresia. Proper functioning of this mechanism may be a new strategy for the treatment of ovarian dysfunctions associated with an imbalance in content of germ cells in the ovaries, such as premature ovarian failure and polycystic ovary syndrome.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by Rennes Metropole (AIS 2015) and Agence de BioMédecine. This work was supported by funding from Université de Rennes1, Institut National de la Santé et de la Recherche Médicale (INSERM) and CHU de Rennes. A.B. is funded in part by the program Actions Concertées Interpasteuriennes (ACIP) and a research grant from the European Society of Pediatric Endocrinology. This work is supported by the Agence Nationale de la Recherche Grants ANR-17-CE14-0038 and ANR-10-LABX-73. The authors declare no competing interests.

[Anonymity of gamete donation and genetic testing]

Development of genetic testing direct-to-consumer (DTC) for recreational purposes, although prohibited in France, is a real challenge to the current practice of gamete donation. Indeed, anonymity is a fundamental principle contributing to the ethics of donation. This principle is weakened due to the availability to the general public of these tests on the Internet. Several thousands of people are conceived by gamete donation worldwide, some of whom do not know how they were conceived. Gamete donors should be informed that their anonymity is no longer guaranteed, as they can be found by homologies of their DNA, or that of a parent or a child, potentially available in databases. Thus, adults conceived by gamete donation but not informed by their parents can discover their way of conception. Recipients of gamete donation should also be informed that their child's DNA will establish the biological discrepancy and they should be encouraged to disclose the conception to their child. Several countries now allow children conceived by donation to obtain donor's identity. In France, the Bioethics Law is currently being finalized and will now allow access to donor's identity for people conceived by gamete donation.

Myelinosome-like vesicles in human seminal plasma: A cryo-electron microscopy study

Seminal plasma is particularly rich in extracellular vesicles. Myelinosomes are membranous organelles described throughout the seminiferous epithelium of the testis but never reported in semen. Our aim was to determine the presence of myelinosomes in human seminal plasma. Transmission electron microscopy and cryo electron microscopy analysis of standard myelinosome preparation from TM4 Sertoli cells and human seminal plasma samples. We have specified by cryo-EM the morphological aspect of "standard" myelinosomes isolated from the culture media of TM4 Sertoli cells. Vesicles with the same morphological appearance were revealed in human seminal plasma samples. Human seminal plasma contains a population of large EV (average diameter 200 nm) whose morphological appearance resemble those of myelinosomes. Defining the specific biomarkers and functionalities of myelinosome in human seminal plasma are the concerns to be addressed in our further research.