Project description:Chromosome aneuploidy increases in oocytes with maternal age, and is considered the leading cause for the increased incidence of infertility, miscarriage, and birth defects. Using mRNA-Sequencing of oocytes from 12 month old mouse versus 3 month young mouse, we identified a spindle assembly checkpoint gene, BubR1, whose expression was significantly decreased. We employed a mRNA microinjection based approach to increase BubR1 expression in aging oocytes. We find that increased expression of BubR1 protects against aneuploidy and chromosome misalignment in aging oocytes. After in vitro fertilization, the embryos derived from BubR1 increased expression aging oocytes exhibited chromosome stability as robust as those of the young ones. Furthermore, following embryo transfer, these embryos showed greatly improved developmental competency, with comparable levels of full-term development to those of the young ones. These results indicate that the decline in oocyte quality may be reversible and could lead to treatments that prolong female fertility. Examination of the effect of maternal aging on the mRNA expression in the mature oocytes of the female mice. Naturally ovulated mature oocytes (MII stage) were collected from 6 young (3 month) and 6 aging (12 month) female mice (3 oocytes per mice, 18 oocytes for each group).
Project description:Chromosome aneuploidy increases in oocytes with maternal age, and is considered the leading cause for the increased incidence of infertility, miscarriage, and birth defects. Using mRNA-Sequencing of oocytes from 12 month old mouse versus 3 month young mouse, we identified a spindle assembly checkpoint gene, BubR1, whose expression was significantly decreased. We employed a mRNA microinjection based approach to increase BubR1 expression in aging oocytes. We find that increased expression of BubR1 protects against aneuploidy and chromosome misalignment in aging oocytes. After in vitro fertilization, the embryos derived from BubR1 increased expression aging oocytes exhibited chromosome stability as robust as those of the young ones. Furthermore, following embryo transfer, these embryos showed greatly improved developmental competency, with comparable levels of full-term development to those of the young ones. These results indicate that the decline in oocyte quality may be reversible and could lead to treatments that prolong female fertility.
Project description:The decline in oocyte quality is a limiting factor of female fertility; however, strategies to maintain the oocyte quality of aged women are not available. In this study, we showed that growth hormone (GH) supplementation in vivo not only alleviated the decline in oocyte number caused by aging, but also improved the quality and developmental potential of aged oocytes. Strikingly, GH supplementation reduced aneuploidy in aged oocytes. Proteomic analysis indicated that the ERK1/2 pathway was involved in the reduction in aneuploidy rate of aged oocytes, as confirmed both in vivo and in vitro. In addition, JAK2 might be involved in the regulation of ERK1/2 by GH in aged oocytes. Collectively, our findings revealed that GH supplementation protects oocytes from aging-related aneuploidy and enhances the quality of aged oocytes, and could be used to improve the outcome of assisted reproduction in aged women.
Project description:Mosaic-variegated aneuploidy (MVA) syndrome is a rare childhood disorder characterized by biallelic BUBR1, CEP57, or TRIP13 aberrations, increased chromosome missegregation, and a broad spectrum of clinical features, including various cancers, congenital defects, and progeroid pathologies. To investigate the mechanisms underlying this disorder and its phenotypic heterogeneity, we mimicked the BUBR1L1012P mutation in mice (BubR1L1002P) and combined it with two other MVA variants, BUBR1X753 and BUBR1H, generating a truncated protein and low amounts of wildtype protein, respectively. Whereas, BubR1X753/L1002P and BubR1H/X753 mice die prematurely, BubR1H/L1002P mice are viable and exhibit many MVA features, including cancer predisposition and various progeroid phenotypes, including short lifespan, dwarfism, lipodystrophy, sarcopenia, and low cardiac stress tolerance. Strikingly, although these mice had a similar reduction in total BubR1 and spectrum of MVA phenotypes as BubR1H/H mice, several progeroid pathologies were attenuated in severity, which in skeletal muscle coincided with reduced senescence-associated secretory phenotype (SASP) complexity. Additionally, mice harboring heterozygous BUBR1 MVA variants developed mild MVA pathologies later in life, with alleles conferring unique phenotypic profiles. Together, these data demonstrate that subtle BUBR1 allelic effects contribute to disease heterogeneity in both MVA patients and heterozygous carriers of MVA mutations, independent of aneuploidy rates and BUBR1 protein levels.
Project description:Mosaic-variegated aneuploidy (MVA) syndrome is a rare childhood disorder characterized by biallelic BUBR1, CEP57, or TRIP13 aberrations, increased chromosome missegregation, and a broad spectrum of clinical features, including various cancers, congenital defects, and progeroid pathologies. To investigate the mechanisms underlying this disorder and its phenotypic heterogeneity, we mimicked the BUBR1L1012P mutation in mice (BubR1L1002P) and combined it with two other MVA variants, BUBR1X753 and BUBR1H, generating a truncated protein and low amounts of wildtype protein, respectively. Whereas, BubR1X753/L1002P and BubR1H/X753 mice die prematurely, BubR1H/L1002P mice are viable and exhibit many MVA features, including cancer predisposition and various progeroid phenotypes, including short lifespan, dwarfism, lipodystrophy, sarcopenia, and low cardiac stress tolerance. Strikingly, although these mice had a similar reduction in total BubR1 and spectrum of MVA phenotypes as BubR1H/H mice, several progeroid pathologies were attenuated in severity, which in skeletal muscle coincided with reduced senescence-associated secretory phenotype (SASP) complexity. Additionally, mice harboring heterozygous BUBR1 MVA variants developed mild MVA pathologies later in life, with alleles conferring unique phenotypic profiles. Together, these data demonstrate that subtle BUBR1 allelic effects contribute to disease heterogeneity in both MVA patients and heterozygous carriers of MVA mutations, independent of aneuploidy rates and BUBR1 protein levels.
Project description:Chromosome segregation errors in oocytes lead to the production of aneuploid eggs, which are the leading cause of pregnancy loss and of several congenital diseases such as Down syndrome. The frequency of chromosome segregation errors in oocytes increases with maternal age, especially at a late stage of reproductive life. How aging at various life stages affects oocytes differently remains poorly understood. In this study, we describe aging-associated changes in the transcriptome profile of mouse oocytes throughout reproductive life. Our single-oocyte comprehensive RNA sequencing using RamDA-seq revealed that oocytes undergo transcriptome changes at a late reproductive stage, whereas their surrounding cumulus cells exhibit transcriptome changes at an earlier stage. Calorie restriction, a paradigm that reportedly prevents aging-associated egg aneuploidy, promotes a transcriptome shift in oocytes with the up-regulation of genes involved in chromosome segregation. This shift is accompanied by the improved maintenance of chromosomal cohesin, the loss of which is a hallmark of oocyte aging and causes chromosome segregation errors. These findings have implications for understanding how oocytes undergo aging-associated functional decline throughout their reproductive life in a context-dependent manner.
Project description:Aneuploidy and aging are correlated; however, a causal link between these two phenomena has remained elusive. Here we show that yeast disomic for a single native yeast chromosome generally have a decreased replicative lifespan. In addition, the extent of this lifespan deficit correlates with the size of the extra chromosome. We identified a mutation in BUL1 that rescues both the lifespan deficit and a protein trafficking defect in yeast disomic for chromosome 5. Bul1 is an E4 ubiquitin ligase adaptor involved in a protein quality-control pathway that targets membrane proteins for endocytosis and destruction in the lysosomal vacuole thereby maintaining protein homeostasis. Concurrent suppression of the aging and trafficking phenotypes suggests that disrupted membrane protein homeostasis in aneuploid yeast may contribute to their accelerated aging. The data reported here demonstrate that aneuploidy can impair protein homeostasis, shorten lifespan, and may contribute to age-associated phenotypes. These are all CGH arrays comparing DNA content between the indicated strain of interest and a wt control.
Project description:Our study demonstrates a protective effect for metformin against the decreased quality of aged oocytes to potentially improve ART success rates and illustrates a potential strategy to prevent or delay reproductive aging.
Project description:Leanness is associated with increased lifespan and is linked to favorable metabolic conditions promoting life extension. We show here that deficiency of the lipid synthesis enzyme acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), which reduces body fat in mice, promotes longevity. Female DGAT1-deficient mice were protected from age-related increases in body fat, non-adipose tissue triglycerides, and markers of inflammation in white adipose tissue. These metabolic changes were accompanied by an increased mean and maximal lifespan of ~25% and ~10%, respectively. The gene expression profile of DGAT1-deficient mice was not highly correlated with calorie restriction of sex and age matched wild-type littermates. Our findings indicate that loss of DGAT1-mediated lipid synthesis results in leanness, protects against age-related metabolic consequences, and thus extends longevity. Liver gene expression profiles between short-term calorie restricted wild-type (WTCR) and Dgat1 deficient (KO) middle-aged (15-16 mo) female mice were compared to determine if calorie restriction and Dgat1 deficiency rely on common regulatory pathways for the promotion of longevity. Both CR and KO were compared to middle-aged wild-type female littermates fed a standard chow diet ad libitum (WTAL).
Project description:Leanness is associated with increased lifespan and is linked to favorable metabolic conditions promoting life extension. We show here that deficiency of the lipid synthesis enzyme acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), which reduces body fat in mice, promotes longevity. Female DGAT1-deficient mice were protected from age-related increases in body fat, non-adipose tissue triglycerides, and markers of inflammation in white adipose tissue. These metabolic changes were accompanied by an increased mean and maximal lifespan of ~25% and ~10%, respectively. The gene expression profile of DGAT1-deficient mice was not highly correlated with calorie restriction of sex and age matched wild-type littermates. Our findings indicate that loss of DGAT1-mediated lipid synthesis results in leanness, protects against age-related metabolic consequences, and thus extends longevity.