BACKGROUND:Hypertrophic cardiomyopathy (HCM) is a common hereditary cardiac disorder characterized by left ventricular hypertrophy, outflow tract obstruction, arrhythmias, and increased risk of sudden cardiac death. METHODS:Clinical phenotypes and family histories were collected from affected individuals. Whole-exome sequencing (WES) followed by Sanger sequencing identified and validated genetic variants. In silico tools predicted splicing effects, with aberrant splicing confirmed by minigene assays. RESULTS:The proband, a 33-year-old male with asymmetric obstructive HCM, exhibited characteristic electrocardiographic, echocardiographic, cardiac MRI, and histopathological findings. WES revealed MYBPC3 c.787G>A and MYH6 c.804G>C (p.Leu268=) variants. Segregation analysis showed that only the synonymous MYH6 variant co-segregated with HCM in affected family members. This variant was absent from public databases (gnomAD and ClinVar) and the literature as of December 15, 2025. Although three in silico tools predicted negligible splicing impact, minigene assays in HEK293T and HeLa cells revealed partial exon 10 skipping, resulting in an in-frame deletion (p.Leu268_Asp300del) in approximately 6.8% and 4.7% of transcripts, respectively. CONCLUSION:The synonymous MYH6 c.804G>C variant promotes exon skipping and is associated with HCM. This study provides functional evidence supporting its potential pathogenicity and underscores the value of experimental validation in genetic diagnosis. These findings highlight the limitations of computational predictions and emphasize the importance of functional assays for evaluating synonymous variants in sarcomeric genes.

Objective:To investigate the clinical manifestations and genetic basis of childhood-onset dystonia-28 (DYT28) associated with a variant in the KMT2B gene. Methods:A female patient, her mother, and her husband, who presented at Zhejiang Provincial People's Hospital in November 2024, were enrolled in this study. Clinical data were collected, and trio-based whole-exome sequencing (WES) was performed using peripheral blood samples obtained from all three individuals. To further evaluate the effect of the identified variant on RNA splicing, mRNA sequencing (mRNA-seq) and Sanger sequencing were subsequently performed. This study was approved by the Medical Ethics Committee of Zhejiang Provincial People's Hospital (Approval No. QT2026084). Results:The patient presented with gait abnormalities beginning after 10 years of age, accompanied by impaired mathematical ability and language communication difficulties. Her mother exhibited similar clinical manifestations, including gait disturbance, language impairment, and a history of scoliosis. WES identified a heterozygous synonymous variant in exon 23 of the KMT2B gene, c.5076 G>A (p.Lys1692 =), in both the patient and her mother. mRNA-seq analysis demonstrated that the variant produced two aberrantly spliced transcripts: complete skipping of exon 23 and retention of an 18-bp sequence derived from the 5' end of intron 23. According to the guidelines of the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic based on the following evidence: PVS1_Strong, PP4 and PM2_Supporting. Conclusion:The KMT2B c.5076 G>A (p.Lys1692 =) variant is likely the genetic cause of childhood-onset dystonia-28 in this patient. This study expands the mutational spectrum of KMT2B and provides additional evidence to support the genetic diagnosis and counseling of patients with KMT2B-related dystonia.

Abstract The b 0,+ transporter ( SLC3A1 / SLC7A9 ) imports cystine and selenocystine at the enterocyte apical membrane and defines a selenium-utilization program in the healthy human intestine (He et al., bioRxiv 2026); how this program is altered in disease is unknown. Using a multi-cohort single-cell framework with donor-level statistics, we find that inflammation and cancer remodel a single epithelial redox-currency axis in opposite directions. In adult Crohn’s disease, b 0,+ co-expression in small-intestinal enterocytes was suppressed (median 4.9% vs 34% positive; P = 0.008) but preserved in paediatric IBD; this loss reflected replacement of b 0,+ -high mature enterocytes by a dedifferentiated state rather than transcriptional disruption, with the SLC7A9 - SELENOP coupling intact. Downstream, GPX4 alone was selectively suppressed while the selenocysteine-incorporation machinery was preserved, priming the epithelium for ferroptosis in a severity-graded manner. Inflammatory cytokines (IFNγ, TNF) suppressed the selenium pole in small-intestinal enteroids, and a network knockout indicated that b 0,+ supports the selenoproteome through substrate supply rather than transcriptional control; an independent patient proteome and a Caco-2 polarization model corroborated the axis. Colorectal-cancer colonocytes showed the opposing pole, near-absent b 0,+ with induction of the xCT/thiol program ( P = 5.6 × 10 −5 ) and a ferroptosis-resistant configuration. Thus b 0,+ marks the supply node of a dual-pole selenium-thiol axis: inflammation collapses the selenium pole toward a ferroptosis-prone dedifferentiated state, whereas cancer bypasses it toward an xCT antioxidant pole. The baseline axis state is an exploratory correlate of anti-TNF response and a candidate point of disease-associated vulnerability.

Abstract Selenium is an essential trace element incorporated into selenoproteins as selenocysteine, yet the intestinal cellular programs associated with selenium utilization remain poorly defined. Here, we performed a large-scale single-cell transcriptomic analysis of 169,068 human enterocytes from 105 donors to systematically profile nine candidate selenium transporter systems and their relationship to selenoprotein expression. Among all transporters examined, the b 0+ amino acid transporter system (SLC3A1/SLC7A9) showed the strongest and most maturation-independent association with selenoproteins, including SELENOP (Spearman r = 0.489) and GPX4 ( r = 0.392), with enrichment across 21 of 24 detected selenoproteins in b 0+ -complete versus transporter-negative enterocytes. These associations were robust across individual donors and confirmed by pseudobulk validation, and were only partially explained by enterocyte maturation state, intestinal segment, and sequencing depth after covariate adjustment, indicating both differentiation-dependent and differentiation-independent components. Furthermore, enterocytes carrying the b 0+ complex expressed a non-canonical LRP repertoire (LRP1, LRP5 and LRP6) rather than the canonical SELENOP receptors LRP2 and LRP8; this co-expression was maturation-dependent, nominating these LRPs as candidate intestinal SELENOP-handling receptors. Together, these single-cell data identify b 0+ transporter expression as a marker of a selenoprotein-enriched enterocyte state in the human intestine.

OBJECTIVES:Cystine stones account for 1%‒2% of adult and up to 10% of pediatric kidney stones. They result from cystinuria, an autosomal recessive disorder caused by mutations in solute carrier family 3 member 1 (SLC3A1) and SLC7A9, which encode the renal cystine transporter subunits. These mutations impair cystine reabsorption, raising urinary cystine levels and driving stone formation. Current diagnostic options remain limited in terms of detecting molecular dysfunctions. Thus, we aimed to develop a nonradioactive, cell-based method for the functional assessment of cystine transporters and mutation-specific pathologies. METHODS:Using human embryonic kidney 293 (HEK293) cells transiently co-expressing wild-type or mutant SLC3A1 and SLC7A9, we developed an integrated approach that combined a selenocystine-based fluorescence uptake assay with AlphaFold3-based structural predictions to rapidly and accurately assess cystine transporter function and the molecular impact of genetic mutations. RESULTS:The affinity of the SLC3A1/SLC7A9 complex was comparably apparent for selenocystine (Michaelis constant Km=(156.3±24.2) μmol/L) and cystine (literature Km approximately 200 μmol/L). Using operational thresholds (mild >60%, moderate 20%‒60%, severe <20% residual activity), the assay differentiated the functional impacts of eight clinically characterized variants, including SLC7A9 A70V, A182T, G105R, R333W, V170M, A354T, and P482L, and SLC3A1 M467T, with categorical assignments consistent with previously published radioisotope-based functional data. AlphaFold3 modeling, combined with molecular docking, provides mechanistic interpretations of the dysfunction observed in the P482L and A354T mutants. CONCLUSIONS:The integrated approach employed in this work, which combines a sensitive selenocystine fluorescence assay with artificial intelligence (AI)-powered structural analysis, enables the rapid, precise diagnosis of cystinuria variants. This platform is compatible with standard microplate-reader infrastructure and offers potential utility in variant-interpretation pipelines and future genotype-guided therapeutic decision-making, pending prospective clinical validation.

Background Cystine stones, a rare but recurrent type of kidney stones, primarily result from cystinuria, an inherited disorder caused by mutations in the genes SLC3A1 and SLC7A9 , which encode renal cystine transporters. These mutations impair cystine reabsorption, resulting in elevated urinary cystine concentrations and stone formation. Current diagnostic methods are limited, particularly for detecting molecular-level dysfunctions. We aimed to develop a nonradioactive method for functional assessment of cystine transporters and mutation-specific pathologies. Methods We designed an innovative diagnostic approach combining a selenocystine-based fluorescence assay with structural predictions using AlphaFold to rapidly and accurately assess cystine transporter function and the molecular impacts of genetic mutations. Results Our assay demonstrated comparable transport efficiencies of cystine and selenocystine by the SLC3A1/SLC7A9 complex, and effectively differentiated mild, moderate, and severe functional impairments associated with known clinical mutations, including A354T and P482L. Structural modeling further provided mechanistic insights into mutation-induced dysfunctions. Conclusion This integrated approach—combining a sensitive selenocystine fluorescence assay with AI-powered structural analysis—enables rapid, precise diagnosis of cystinuria variants and delivers mechanistic insights for personalized therapeutic strategies. ### Competing Interest Statement The authors have declared no competing interest. Zhejiang Provincial Natural Science Foundation of China, LMS25H160004 Zhejiang Provincial Medical and Health Science and Technology Programs, 2023KY650, 2021KY080

Oligo-astheno-teratozoospermia (OAT), which is a common cause of male infertility, can be caused by genetic factors. This study reports on a case of a male patient suffering from infertility concomitant with OAT. Whole-exome sequencing (WES) confirmed the presence of a homozygous variant (NM_003462: c.464-1G > A) in the DNALI1 gene via Sanger sequencing. Immunofluorescence staining demonstrated that the DNALI1 signal was nearly undetectable in the patient’s sperm. Bioinformatics analysis revealed that this mutation could reverse the splicing of the exon 4 acceptor splice site. A minigene experiment was performed to verify the mutation and the results confirmed that the mutation disrupted the splicing. Our findings show that this rare mutation in DNALI1 contributes to male infertility and OAT in humans, thereby expanding our understanding of the causes and pathogenesis of male infertility. This knowledge facilitates genetic counseling, clinical diagnosis, and therapeutic development of male infertility.

As the understanding of the mechanisms of SARS-CoV-2 infection continues to grow, researchers have come to realize that ACE2 and TMPRSS2 receptors are not the only way for the virus to invade the host, and that there are many molecules that may serve as potential receptors or cofactors. The functionality of these numerous receptors, proposed by different research groups, demands a fast, simple, and accurate validation method. To address this issue, we here established a DnaE intein-based cell-cell fusion system, a key result of our study, which enables rapid simulation of SARS-CoV-2 host cell infection. This system allowed us to validate that proteins such as AXL function as SARS-CoV-2 spike protein receptors and synergize with ACE2 for cell invasion, and that proteins like NRP1 act as cofactors, facilitating ACE2-mediated syncytium formation. Our results also suggest that mutations in the NTD of the SARS-CoV-2 Delta variant spike protein show a preferential selection for Spike-AXL interaction over Spike-LDLRAD3. In summary, our system serves as a crucial tool for the rapid and comprehensive verification of potential receptors, screening of SARS-CoV-2-neutralizing antibodies, or targeted drugs, bearing substantial implications for translational clinical applications.

Abstract Study question What are the effect and corresponding mechanisms of chromosome chaos of sperm caused by mutation of the MEIKIN gene on preimplantation embryo development? Summary answer Sperm chromosome chaos induced by MEIKIN gene mutations directly causes blastocyst formation failure by affecting the activation of the embryonic genome and lineage differentiation. What is known already In mice, Meikin is a meiosis-specific kinetochore factor that plays a crucial role in mono-orientation and protection of centromeric cohesion in meiosis I and the regulation of chromosome alignment during meiosis II. Both male and female Meikin gene knockout mice are completely infertile. Infertility in male Meikin-/- mice originates from defects in meiotic chromosome segregation and subsequent spermatogenesis. To our knowledge, no mutation of the MEIKIN gene has been reported in humans. Study design, size, duration In this study, semen from three patients with MEIKIN mutations and arrested embryos from one of them were analyzed to determine the effect of MEIKIN mutations on sperm and early embryonic development. Participants/materials, setting, methods Three male patients with MEIKIN mutations with a specific clinical phenotype were recruited. We assessed mutant sperm morphology using Papanicolaou staining. Sperm FISH and single sperm chromosome aneuploidy analysis（CNV-seq） were applied to identify mutant sperm Chromosomal abnormality. We also investigated the chromosome constitution and gene expression of the arrested embryos from one patient by parallel single-cell genome and transcriptome sequencing. Main results and the role of chance Novel mutations in the MEIKIN gene were identified in three infertility males with a specific clinical phenotype（They had good-quality embryos on day 3, but these embryos repeatedly failed to implant or develop to the blastocyst stage）. Routine semen assessments were conducted based on the WHO’s guidelines, and all these patients were diagnosed with oligoasthenoteratozoospermia. Sperm FISH showed that the frequencies of aneuploidies in spermatozoa were significantly higher than the normal control（89.05%,70.9%,93.24% vs. 5.03%）, and the CNV-seq analysis of single spermatozoa confirmed mutant sperm had severe chromosome chaos. Each cell of the arrested embryos from one patient had complicated chromosomal abnormalities, and the abnormal chromosomes were mainly derived from sperm. At the gene expression level, these embryos were arrested at the 8-cell to morula stage transition, and defects activation of a large ZGA and lineage specification genes led to blastocyst formation failure. Limitations, reasons for caution In this study, we discovered that mutations in MEIKIN caused male infertility manifesting as sperm chromosome chaos and blastocyst formation failure. However, the molecular mechanism of the sperm chromosome chaos involved in blastocyst formation needs to be further illuminated by using Meikin knockout mouse models. Wider implications of the findings We first reported that male with MEIKIN mutations is related to severe sperm chromosome abnormalities and blastocyst formation failure. Therefore, In the process of ICSI, if there are good-quality cleavage embryos that repeatedly fail to implant or develop to the blastocyst stage, it is recommended to examine male factors concurrently Trial registration number not applicable

The oocyte cumulus complex is mainly composed of an oocyte, the perivitelline space, zona pellucida and numerous granulosa cells. The cumulus granulosa cells (cGCs) provide a particularly important microenvironment for oocyte development, regulating its growth, maturation and meiosis. In this study, we studied the internal structures and cell-to-cell connections of mouse cGCs using focused ion beam scanning electron microscopy (FIB-SEM). We reconstructed three-dimensional models to display characteristic connections between the oocyte and cGCs, and to illustrate various main organelles in cGCs together with their interaction relationship. A special form of cilium identified in granulosa cell was never reported in previous literature.

Primary ovarian insufficiency (POI) is among the foremost causes of women infertility due to premature partial or total loss of ovarian function. Resistant ovary syndrome (ROS) is a subtype of POI manifested as normal ovarian reserve but insensitive to gonadotropin stimulation. Inactivating variants of follicle-stimulating hormone receptor (FSHR), a class A G-protein coupled receptor, have been associated with POI and are inherited via an autosomal recessive pattern. In this study, we investigated the genetic causes of a primary infertility patient manifested as POI with ROS, and elucidated the structural and functional impact of variants of uncertain significance. Next-generation sequencing (NGS) combined with Sanger sequencing revealed novel compound heterozygous FSHR variants: c.1384G>C/p.Ala462Pro and c.1862C>T/p.Ala621Val, inherited from her father and mother, respectively. The two altered amino acid sequences, localized in the third and seventh transmembrane helix of FSHR, were predicted as deleterious by in silico prediction. In vitro experiments revealed that the p.Ala462Pro variant resulted in barely detectable levels of intracellular signaling both in cAMP-dependent CRE-reporter activity and ERK activation and displayed a severely reduced plasma membrane receptor expression. In contrast, the p.Ala621Val variant resulted in partial loss of receptor activation without disruption of cell surface expression. In conclusion, two unreported inactivating FSHR variants potentially responsible for POI with ROS were first identified. This study expands the current phenotypic and genotypic spectrum of POI.

Abstract Study question Whether the activation of DUX4, a key inducer in the process of zygotic genome activation (ZGA), is associated with telomere length. Summary answer Telomeres regulate the expression of DUX4/Dux through chromatin remodeling and are thereby involved in ZGA. What is known already In human early embryos, the expression of DUX4 is activated as a key inducer in the initial stage of ZGA, and it, in turn, activates hundreds of genes in the cleavage-stage embryo. Human DUX4 is localized to the subtelomeric region 4q35.2 with a D4Z4 repeat of approximately 10 to 100 units that encodes a homeodomain transcription factor. DUX4 expression is inversely proportional to the telomere length in myoblasts/myotubes derived from FSHD patients Study design, size, duration We characterize the dynamics of telomeres during preimplantation development, and assessed the relationship between the expression of DUX4/Dux and telomere length in preimplantation embryos and human embryonic stem cells. Participants/materials, setting, methods All sperm and immature oocytes were collected after obtaining written informed consent from the donor couples. Telomere length in gametes and early embryos by telomere-specific quantitative fluorescence in situ hybridization (Q-FISH). Main results and the role of chance Zygotic genome activation (ZGA) is initiated once the genome chromatin state is organized in the newly formed zygote. While telomeres are specialized chromatin structures at the ends of chromosomes and are reset during early embryogenesis, the details and significance of telomere changes in preimplantation embryos remain unclear. We demonstrated that the telomere length was shortened in the minor ZGA stage and significantly elongated in the major ZGA stage of human and mouse embryos. Expression of the ZGA pioneer factor DUX4/Dux was negatively correlated with the telomere length. ATAC-sequencing suggested that the chromatin accessibility peaks on the DUX4 promoter region (i.e., the subtelomere of chromosome 4q) were transiently augmented in human minor ZGA. Reduction of telomeric heterochromatin H3K9me3 in the telomeric region also synergistically activated DUX4 expression with p53 in hESCs. We propose herein that telomeres regulate the expression of DUX4/Dux through chromatin remodeling and are thereby involved in ZGA. Limitations, reasons for caution Since the mouse Dux gene is not located at the end of the chromosome, the classical telomere position effect (TPE) pathway may not involve in its activation in early embryos. 3D analysis as presented by Hi-C may be able to make a greater breakthrough in confirming the relationship. Wider implications of the findings We herein provided detailed data on changes in the telomere length during ZGA in human and mouse preimplantation embryos, explored the possibility that the TPE affects regulation of DUX4/Dux gene expression in embryos, and suggest that telomere chromatin remodeling is involved in the ZGA process. Trial registration number not applicable

Zygotic genome activation (ZGA) is initiated once the genome chromatin state is organized in the newly formed zygote. Telomeres are specialized chromatin structures at the ends of chromosomes and are reset during early embryogenesis, while the details and significance of telomere changes in preimplantation embryos remain unclear. We demonstrated that the telomere length was shortened in the minor ZGA stage and significantly elongated in the major ZGA stage of human and mouse embryos. Expression of the ZGA pioneer factor DUX4/Dux was negatively correlated with the telomere length. ATAC sequencing data revealed that the chromatin accessibility peaks on the DUX4 promoter region (i.e., the subtelomere of chromosome 4q) were transiently augmented in human minor ZGA. Reduction of telomeric heterochromatin H3K9me3 in the telomeric region also synergistically activated DUX4 expression with p53 in human embryonic stem cells. We propose herein that telomeres regulate the expression of DUX4/Dux through chromatin remodeling and are thereby involved in ZGA.

The aim of this study was to evaluate the effects of sperm proteasome activity on fertilization outcome and embryo development after IVF. Following density gradient centrifugation for IVF purpose, the spermatozoa of 84 infertile patients with tubal factor were evaluated by luciferase enzymatic activity to assess the proteasome quantity. The mean age of patients was 33.8 years, and the mean concentration of human spermatozoa 26S proteasome was 674.53 ng/ml. After IVF, the embryos were scored for morphology. The spermatozoa proteasome activity was both positively correlated with fertilization rate in vitro (P = 0.0003) and 2PN rate (P = 0.0007). Compared to low fertilization rate group, the high fertilization rate group showed a significantly higher level of spermatozoa proteasome activity (P = 0.002). In conclusion, sperm proteasome activity provides additional data on sperm functional capacity in terms of fertilization during IVF.

Infertility is a social and medical problem around the world and the incidence continues to rise. Thin endometrium (TE) is a great challenge of infertility treatment, even by in vitro fertilization and embryo transfer. It is widely believed that TE impairs endometrium receptivity. However, only a few studies have explained the molecular mechanism. Herein, in order to reveal the possible mechanism, we sampled endometrium from a TE patient and a control volunteer and got a transcriptomic atlas of 18 775 individual cells which was constructed using single-cell RNA sequencing, and seven cell types have been identified. The cells were acquired during proliferative and secretory phases, respectively. The proportion of epithelial cells and stromal cells showed a significant difference between the TE group and the control group. In addition, differential expressed genes (DEGs) in diverse cell types were revealed, the enriched pathways of DEGs were found closely related to the protein synthesis in TE of both proliferative and secretory phases. Some DEGs can influence cell-type ratio and impaired endometrial receptivity in TE. Furthermore, divergent expression of estrogen receptors 1 and progesterone receptors in stromal and epithelial cells were compared in the TE sample from the control. The cellular and molecular heterogeneity found in this study provided valuable information for disclosing the mechanisms of impaired receptivity in TE.

Follicle-stimulating hormone (FSH) brings about physiological actions by activating specific FSH receptor (FSHR) on target cells. FSHR plays an important role in the development of follicles, the production of estradiol in females, the maintenance of the function of testicular Sertoli cells and the spermatogenesis in males. In the past two decades, a large number of cases have been used to identify the inactivating/activating mutations and single nucleotide polymorphisms of FSHR gene. According to the genotype-phenotype correlation research and in vitro functional experiments of FSHR gene may help to understand the causes of infertility in affected patients. This review summarizes the inactivating mutations which have been reported in different parts of FSHR and their impacts on female reproductive system.

The ubiquitin-proteasome system (UPS) is a protein degradation system in addition to lysosomal system in eukaryotic cells. UPS can eliminate misfolded proteins and reduce the occurrence of aging diseases caused by the accumulation of misfolded proteins. The selective protein degradation of UPS acts on the mitosis and meiosis process of spermatogonia, which is very important for spermatogenesis. In addition, important reproductive processes such as sperm capacitation, acrosome reaction, penetrating zona pellucida and elimination of sperm mitochondria after fertilization are also closely related to UPS. This article reviews the recent literatures on the role of UPS in spermatogenesis, fertilization and its relationship with infertility.

Objective:To establish and evaluate a follicle isolation method, combination of enzymatically digestion with strainer filtration, for synchronously collecting mouse follicles across different developmental stages.Methods:Pre-cutted ovarian tissue blocks were digested with enzymes mixed by Collagenase I and DNase I, and then filtered through three different pore size cell strainers to synchronously separate the follicles at developmental stages. The follicles obtained by turning over and washing the 100 μm strainer were recorded as group A (>100 μm), as same as the follicles obtained by turning over and washing the 40 μm strainer were recorded as group B (40-100 μm), and the follicles obtained by turning over and washing the 20 μm strainer were recorded as group C (20-40 μm). The quantity, morphology, viability and developmental potency were examined among these harvested follicles.Results:In terms of quantity, follicles in group C accounted for most, followed by follicles in group A, and the follicles in group B were the least. Morphologically, the basal membrane integrity rate of follicles in group C was higher than that of groups B and A ( P<0.001 and P<0.001, respectively). As for viability, the survival rate of follicles in group A was 70.59% (120/170), which was higher than that in group B (51.79%, 58/112) and group C (35.90%, 28/78) ( P=0.001 6 and P<0.001, respectively). In terms of developmental potency, after 96 h of in vitro culture, the diameter of follicles in group A increased from (113.64±9.57) μm to (150.95±45.90) μm ( P=0.002 4), and the diameter of follicles in group B increased from (88.12±9.12) μm to (120.61±18.00) μm ( P<0.001). In group C, monolayer-layer granulosa cells were attached to the follicles within 24 h of culture, and the connection structure between oocytes and granulosa cells was lost. The oocytes were completely exposed and failed to be cultured successfully. Conclusion:Combining enzymatically digestion with multiple strainers filtration is a rapid and effective method for follicle collecting, which is capable to isolate different developmental stage mouse follicles synchronously with morphological integrity, favorable viability and good developmental potency.

We and others have previously shown that abnormal pelvic environment plays an important role in the unexplained infertility of endometriosis. However, whether iron overload caused by ectopic periodic bleeding found in patients with endometriosis participates in endometriosis-associated reproductive failure is unknown. This study aimed to investigate effects of iron at level relevant to pelvic iron overload on the development of preimplantation mouse embryo. Two-cell embryos were collected, and cultured to blastocysts in G1/G2 medium supplemented with iron alone or in combination with iron chelator. The development rates, ATP level, mitochondrial membrane potential (MMP), reactive oxygen species level (ROS), and apoptotic and ferroptotic indices were compared between control and iron treatments across each specific developmental stage. Prolonged exposure to iron remarkably impaired early embryo development in vitro by hampering blastocyst formation (P < 0.001), which could be partly restored by iron chelator (P < 0.001). The arrest of embryo development was linked with iron-initiated mitochondrial dysfunction with reduction of ATP generation and MMP (P < 0.05 and P < 0.001, respectively). Impaired mitochondria altered ROS accumulation post-iron exposure at morula stage and blastocyst stage (P < 0.05). Moreover, Iron-exposed blastocyst stage embryos showed higher apoptotic and ferroptotic rates (P < 0.001 and P < 0.05, respectively). Our results highlight that pathologically relevant level of iron compromises preimplantation mouse embryo development by disrupting mitochondrial function and triggering both apoptosis and ferroptosis, which implicates that excess iron found in peritoneal fluid of women with endometriosis likely participates in endometriosis-associated reproductive failure.

Obesity and its related severe consequences have been a major public health problem worldwide. A significant weight gain and intra-abdominal adipose tissue accumulation are observed as women begin the menopausal transition. A number of clinical and basic research indicate that ovarian hormone may play a crucial role. However, the underlying mechanisms are largely unknown. In this chapter, we aim to systematically review the literature in the influences of ovarian hormone on the physiology of lipid and glucose metabolism, obesity-related hormone, and the regulation of body weight by the dietary intake, feeding behavior. A variety of research modalities have been used to explore the effects of MHT in perimenopausal women. Hence, we will also summarize the latest progress of MHT use on the effect of body mass, body fat redistribution, and insulin resistance, which lead to protective cardiometabolic effects.