CDKN1A Deficiency in Zebrafish Promote Follicle Maturation and Degeneration Mediated by CRISPR/Cas9 Targeted Disruption
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ABSTRACT: CDKN1A plays multiple roles in distinctive biological processes, such as cellular proliferation, apoptosis, DNA repairing, and etc. In mouse, Cdkn1a deficiency led to cell arrest at G1 phase, and also reported that Cdkna1-deficient mice were susceptible to tumorigenesis. However, the functions of Cdkn1a in zebrafish were still elusive due to few studies. Our previous study indicated that Cdkn1a might be closely associated with folliculogenesis, and to further investigate its specific role during folliculogenesis, Cdkn1a was targeted disrupted by CRISPR/Cas9. Interestingly, Cdkn1a-deficient zebrafish were embryonic lethality, resulted in approximate 2% homozygous mutants in adult stage. Furthermore, homozygous mutants have accelerated follicle maturation that faster than WT, and were fertile at young age (2 month). However, the matured or large follicles in mutant soon become dysfunctional due to abnormal oocyte that led to infertile at 3 months. Gradually, the abnormal follicles were undertaken follicle degeneration, resulted in PG follicle enrichment in mutant ovary at 6 months. Similar follicle degeneration phenomenon was also observed in heterozygous mutant ovary at 8 months. The degenerating follicles in mutant were convinced by in situ apoptosis detection kit. To further explore molecular mechanism, RNA-seq and qPCR validation were adopted to identify underlying molecular pathway that involved in Cdkn1a deficient apoptosis. This study firstly reported the functions of Cdkn1a in zebrafish, particular in its critical role in maintenance of normal follicle development, and the special phenotypes in folliculogenesis perfectly interpretation of its dual roles on both proliferation and apoptosis at two different phases, which replenished its novel role in folliculogenesis that expanded our insights.
Project description:Y box-binding protein 1 (YB-1; Ybx1/ybx1) regulates transcription and translation of targeted genes by DNA/RNA-binding. Our previous proteomic study demonstrated a dramatic drop in Ybx1 protein during follicle activation in zebrafish ovary. In this study, we created an ybx1 mutant with CRISPR/Cas9, and showed that the folliculogenesis in the mutant ovary (ybx1-/-) was blocked at pre-vitellogenic (PV)-to-early vitellogenic (EV) transition, leading to small ovaries. The mutant females were therefore sub-fertile with reduced fecundity. RNA-seq and Western blot analyses identified a variety of genes that showed differential expression between mutant ovary (ybx1-/-) and the control (ybx1+/-) including cdkn1a (p21). Disruption of cdkn1a resulted in embryonic lethality. In p21 heterozygotes (cdkn1a+/-), however, follicle activation and maturation in the ovary were both enhanced in contrast to ybx1 mutant (ybx1-/-). Interestingly, partial loss of p21 in heterozygotes (cdkn1a+/-) could rescue the phenotype of ybx1 mutant (ybx1-/-). Folliculogenesis resumed in ybx1-/-;p21+/- females with normal follicle activation, in contrast to the PV-EV blockade in ybx1-/- mutant. Interestingly, the follicle cells from the ybx1-/- mutant follicles displayed a poor proliferative activity in vitro; however, the cells from the ybx1-/-p21+/- follicles resumed normal proliferation compared to that from the wildtype fish. In summary, we demonstrated in this study that Ybx1 played a gatekeeping role in controlling PV-to-EV transition and it might act by suppressing the expression of cdkn1a, a cell cycle inhibitor.
Project description:Dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and benzyl butyl phthalate (BBP) are three phthalates commonly found in consumer products, including the plastic coating of pharmaceuticals and personal care products. Folliculogenesis, a tightly regulated process occurring in the ovary, is the maturation of an immature primordial follicle to a mature antral follicle. Follicles house the oocyte and antral follicles specifically play a crucial role in ovarian steroidogenesis and ovulation. DBP, BBP, and DEHP have been associated with inhibited antral follicle growth in vitro, decreased ovulation rates in vitro, and decreased antral follicle counts in women. However, little is known about the effects of a three-phthalate mixture on antral follicles in vivo. The objective of this study was to evaluate the effects of a human relevant mixture of DBP, BBP, and DEHP on ovarian follicles through proteome profiling analysis. CD-1 female mice (60 days old) were pipet fed tocopherol stripped corn oil (vehicle control) only or a phthalate mixture (52% DBP, 36% DEHP, and 12% BBP dissolved in vehicle) which modeled human follicular fluid concentrations. The mice were treated with 32µg/kg/day (PHT Mix 32; cumulative estimate in general population) and 500µg/kg/day (PHT Mix 500; cumulative estimate in occupationally exposed individuals) for 10 consecutive days. Proteome profiling of antral follicles (>250µm) was performed via label-free tandem mass spectrometry. A total of 5,417 antral follicle proteins were identified in the three groups, of which 194 were differentially abundant between the vehicle and PHT Mix 32 group, and 136 between the vehicle and PHT Mix 500 group. Gene ontology analysis revealed that the two treatments of the phthalate mixture upregulate and downregulate distinctive processes, supporting non-monotonic effects of phthalates on the antral follicle proteome. Taken together, these results reveal that a human relevant mixture of DBP, BBP, and DEHP alters the antral follicle proteome and merits further evaluation to elucidate the molecular mechanisms by which phthalates cause negative reproductive outcomes.
Project description:Primordial follicles are the first class of follicles formed in the mammalian ovary and are comprised of an oocyte surrounded by a layer of squamous pre-granulosa cells. This developmental class remains in a non-growing state until individual follicles activate to initiate folliculogenesis. What regulates the timing of follicle activation and the upstream signals that govern these processes are major unanswered questions in ovarian biology. This is partly due to the paucity of data on staged follicle cells since isolating and manipulating individual oocytes and somatic cells from early follicle stages are challenging. To date, most studies on isolated primordial follicles have been conducted on cells collected from animal-age- or oocyte size-specific samples, which encompass multiple follicular stages. Here, we report a method for collecting primordial follicles and their associated oocytes and somatic cells from neonatal murine ovaries using liberase, DNase I, and Accutase. This methodology allows for the identification and collection of follicles immediately post-activation enabling unprecedented interrogation of the primordial-to-primary follicle transition. Molecular profiling by single-cell RNA sequencing (scRNA-seq) revealed that processes including organelle disassembly and cadherin binding were enriched in oocytes and somatic cells as they transitioned from primordial to the primary follicle stage. Furthermore, targets including WNT4, TGFβ, FOXO3, and a network of transcription factors were identified in the transitioning oocytes and somatic cells as potential upstream regulators that collectively may drive follicle activation. Taken together, we have developed a more precise characterization and selection method for studying staged-follicle cells, revealing several novel regulators of early folliculogenesis.
Project description:Female fertility is determined in part by the size and development of the primordial follicle pool. The current study investigates the role of glial cell-line derived neurotrophic factor (GDNF) in the regulation of primordial follicle development in the ovary. Ovaries from four-day old female rat pups were maintained in organ culture for ten days in the absence (control) or presence of GDNF or kit ligand/stem cell factor (KL). Ovaries treated with GDNF contained a significant increase in developing follicles, similar to that observed with KL treatment previously shown to promote follicle development. The actions of GDNF on the ovarian transcriptome were investigated with a microarray analysis. Immunohistochemical studies demonstrated that GDNF is localized to oocyte cytoplasm in follicles of all developmental stages, as well as to cumulus granulosa cells and theca cells in antral follicles. GDNF receptor alpha 1 (GFRalpha1) staining was localized to oocyte cytoplasm of primordial and primary follicles, and at reduced levels in oocytes of antral follicles. GFRalpha1 was present in mural granulosa cells of antral follicles, theca cells, and the ovarian surface epithelium. The localization studies were confirmed with molecular analysis. Microarray analysis was used to identify changes in the ovarian transcriptome and further elucidate the signaling network regulating early follicle development. Observations indicate that GDNF promotes primordial follicle development and mediates autocrine and paracrine cell-cell interactions required during folliculogenesis. In contrast to the testis, ovarian GDNF is predominantly produced by germ cells (oocytes) rather than somatic cells. Keywords: expression analysis, glial derived neurotrophic factor, follicle transition, ovary
Project description:Folliculogenesis corresponds to the development of follicles leading to either ovulation or degeneration (a process called atresia). Even if atresia involves an apoptosis process, this mechanism is not well understood. The objective of this experiment was : 1) to analyse gene expression in pig granulosa cells of ovarian follicles during atresia using transcriptome analysis with a 9 024 cDNAs microarray, 2) the identification of gene networks involved in pig ovarian follicular atresia. Granulosa cells were isolated from atretic follicles (small, medium or large). Gene expression was analysed by hybridization of nylon cDNA microarrays. The images were quantified using Bzscan software and the data were managed with BASE software. Statistical analysis was performed using R software. Keywords: pig ovary, folliculogenesis, atresia, gene expression, cDNA microarray, bio-analysis
Project description:In mammals, ovarian folliculogenesis leading to the ovulation of completely mature oocytes is a long and complex process that is regulated at different levels. The mechanisms that underlie the selection of one or several dominant follicles as well as the regulation of the number of ovulating follicles are largely unknown. In this project, we proposed to study the genetic determinism that underlies the difference of ovulation rate between species (cattle and pigs), by studying two processes that exist in ovary: follicular development and follicular atresia. Towards this purpose, we made a comparative transcriptomics study on granulosa cells. Pig and cattle comparison was achieved by a transcriptome analysis with a 9K nylon pig microarray (GPL3729) on granulosa cells from either small healthy antral follicles (SHF), small atretic follicles (SAF) or large healthy antral follicles (LHF). The images were quantified using AGscan software and the data were managed with BASE software. Statistical analysis was performed using R software. Transcriptomic analysis on pig and cattle evidenced 997 differentially expressed genes (FDR1%) between the three follicle classes and/or the two species. This research project which implicated three laboratories from INRA: "Laboratoire de Genetique Cellulaire" (UMR444-LGC) , "Station d'Amelioration Genetique des Animaux" (UR 631-SAGA) and "Physiologie des Comportements et de la reproduction" (UMR 85-PRC) benefited from both European funding through SABRE project and French ANR funding through GenOvul project. Keywords: transcriptome analysis, pig, cattle, ovary, folliculogenesis, gene expression, cDNA microarray The data were obtained from 34 RNA samples: 10 small healthy follicles samples (6 for sows and 4 for cows), 13 small atretic follicles samples (7 for sows and 6 for cows) and 11 samples for large healthy follicles (6 for sows and 5 for cows). They were hybridized on a 9K pig nylon microarray (GPL3729).
Project description:In mammalian females, quiescent primordial follicles serve as the ovarian reserve and sustain normal ovarian function and egg production via folliculogenesis. The loss of primordial follicles causes ovarian aging. Cellular senescence, characterized by cell cycle arrest and production of the senescence-associated secretory phenotype (SASP), is associated with tissue aging. In the present study, we report that some quiescent primary oocytes in primordial follicles become senescent in adult mouse ovaries. The senescent primary oocytes share senescence markers characterized in senescent somatic cells. The senescent primary oocytes were observed in young adult mouse ovaries, remained at approximately 15% of the total primary oocytes during ovarian aging from 6 months to 12 months, and accumulated in aged ovaries. Administration of a senolytic drug ABT263 to 3-month-old mice reduced the percentage of senescent primary oocytes and the transcription of the SASP cytokines in the ovary. In addition, led to increased numbers of primordial and total follicles and a higher rate of oocyte maturation and female fertility. Our study provides experimental evidence that primary oocytes, a germline cell type that is arrested in meiosis, become senescent in adult mouse ovaries and that senescent cell clearance reduced primordial follicle loss and mitigated ovarian aging phenotypes.
Project description:Female fertility is determined in part by the size and development of the primordial follicle pool. The current study investigates the role of glial cell-line derived neurotrophic factor (GDNF) in the regulation of primordial follicle development in the ovary. Ovaries from four-day old female rat pups were maintained in organ culture for ten days in the absence (control) or presence of GDNF or kit ligand/stem cell factor (KL). Ovaries treated with GDNF contained a significant increase in developing follicles, similar to that observed with KL treatment previously shown to promote follicle development. The actions of GDNF on the ovarian transcriptome were investigated with a microarray analysis. Immunohistochemical studies demonstrated that GDNF is localized to oocyte cytoplasm in follicles of all developmental stages, as well as to cumulus granulosa cells and theca cells in antral follicles. GDNF receptor alpha 1 (GFRalpha1) staining was localized to oocyte cytoplasm of primordial and primary follicles, and at reduced levels in oocytes of antral follicles. GFRalpha1 was present in mural granulosa cells of antral follicles, theca cells, and the ovarian surface epithelium. The localization studies were confirmed with molecular analysis. Microarray analysis was used to identify changes in the ovarian transcriptome and further elucidate the signaling network regulating early follicle development. Observations indicate that GDNF promotes primordial follicle development and mediates autocrine and paracrine cell-cell interactions required during folliculogenesis. In contrast to the testis, ovarian GDNF is predominantly produced by germ cells (oocytes) rather than somatic cells. Experiment Overall Design: RNA samples from two control groups (pooled untreated cultured ovaries) are compared to two treated groups (pooled cultured ovaries treated with GDNF)
Project description:The pathogenesis of thyroid dysgenesis (TD) is not well understood. Here, using a combination of single-cell RNA and spatial transcriptome sequencing, we identify a subgroup of NF-κB-activated thyrocytes located at the center of thyroid tissues in postnatal mice, which maintained a partially mesenchymal phenotype. These cells actively protruded out of the thyroid primordium and generated new follicles in zebrafish embryos through continuous tracing. Suppressing NF-κB signaling affected thyrocyte migration and follicle formation, leading to a TD-like phenotype in both mice and zebrafish. Interestingly, during thyroid folliculogenesis, myeloid cells played a crucial role in promoting thyrocyte migration by maintaining close contact and secreting TNF-α. We found that cebpa mutant zebrafish, in which all myeloid cells were depleted, exhibited thyrocyte migration defects. Taken together, our results suggest that myeloid-derived TNF-α-induced NF-κB activation plays a critical role in promoting the migration of vertebrate thyrocytes for follicle generation.
Project description:The pathogenesis of thyroid dysgenesis (TD) is not well understood. Here, using a combination of single-cell RNA and spatial transcriptome sequencing, we identify a subgroup of NF-κB-activated thyrocytes located at the center of thyroid tissues in postnatal mice, which maintained a partially mesenchymal phenotype. These cells actively protruded out of the thyroid primordium and generated new follicles in zebrafish embryos through continuous tracing. Suppressing NF-κB signaling affected thyrocyte migration and follicle formation, leading to a TD-like phenotype in both mice and zebrafish. Interestingly, during thyroid folliculogenesis, myeloid cells played a crucial role in promoting thyrocyte migration by maintaining close contact and secreting TNF-α. We found that cebpa mutant zebrafish, in which all myeloid cells were depleted, exhibited thyrocyte migration defects. Taken together, our results suggest that myeloid-derived TNF-α-induced NF-κB activation plays a critical role in promoting the migration of vertebrate thyrocytes for follicle generation.