scholarly journals Spermatozoa telomeres determine telomere length in early embryos and offspring

Reproduction ◽  
2016 ◽  
Vol 151 (1) ◽  
pp. 1-7 ◽  
Author(s):  
C de Frutos ◽  
A P López-Cardona ◽  
N Fonseca Balvís ◽  
R Laguna-Barraza ◽  
D Rizos ◽  
...  
Keyword(s):  
Telomere Length ◽  
Mus Musculus ◽  
Mus Spretus ◽  
Cell Stage ◽  
Young Males ◽  
Early Embryos ◽  
Parent Of Origin ◽  
Telomere Lengthening ◽  
Zygote Stage

Offspring telomere length (TL) has been correlated with paternal TL, but the mechanism for this parent of origin-specific inheritance remains unclear. The objective of this study has been to determine the role of spermatozoa TL in embryonic telomere lengthening by using two mouse models showing dimorphism in their spermatozoa TL: Mus musculus vs Mus spretus and old vs young Mus musculus. Mus spretus spermatozoa displayed a shorter TL than Mus musculus. Hybrid offspring exhibited lower TL compared with Mus musculus starting at the two-cell stage, before the onset of telomerase expression. To analyze the role of spermatozoa telomeres in early telomere lengthening, we compared the TL in oocytes, zygotes, two-cell embryos and blastocysts produced by parthenogenesis or by fertilization with Mus musculus or Mus spretus spermatozoa. TL was significantly higher in spermatozoa compared with oocytes, and it increased significantly from the oocyte to the zygote stage in those embryos fertilized with Mus musculus spermatozoa, but not in those fertilized with Mus spretus spermatozoa or produced by parthenogenesis. A further increase was noted from the zygote to the two-cell stage in fertilized Mus musculus embryos, whereas hybrid embryos maintained the oocyte TL. Spermatozoa TL shortened with age in Mus musculus and the offspring from young males showed a significantly higher TL compared with that fathered by old males. These significant differences were already noticeable at the two-cell stage. These results suggest that spermatozoa telomeres act as a guide for telomerase-independent telomere lengthening resulting in differences in TL that persist after birth.Free Spanish abstract: A Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/151/1/1/suppl/DC1.

91 SPERMATOZOA TELOMERE LENGTH DETERMINES EMBRYONIC TELOMERE LENGTH BEFORE EMBRYONIC GENOME ACTIVATION

2013 ◽  
Vol 25 (1) ◽  
pp. 193
Author(s):  
C. de Frutos ◽  
R. Laguna-Barraza ◽  
P. Bermejo-Alvarez ◽  
D. Rizos ◽  
A. Gutierrez-Adan
Keyword(s):  
Telomere Length ◽  
Mus Musculus ◽  
Mus Spretus ◽  
Telomere Elongation ◽  
Embryonic Genome Activation ◽  
Male Gametes ◽  
Embryonic Genome ◽  
Cell Embryo ◽  
Telomere Lengthening ◽  
Genome Activation

A critical issue for species integrity is the existence of a telomere elongation program during embryogenesis that ensures sufficient telomere reserves in mammalian newborns. Two different mechanisms have been reported to act on telomere elongation during early embryogenesis: first, the telomerase, the ribonucleoprotein that adds telomeric repeats onto the chromosome ends, known to be responsible for the telomere lengthening at the morula-blastocyst transition in mice and bovine; second, in laboratory mice strains, mature oocytes increase the length of their relatively short telomeres between the 1-cell and 2-cell stages by a recombination or ALT-like pathway. In contrast, spermatozoa, the terminally differentiated male gametes, exhibit a very long telomere length (TL). The aim of this study was to clarify the potential role of the spermatozoa TL in the telomere lengthening occurring between oocyte and the 2-cell stage. For this purpose, we used 2 mouse species known to differ greatly in their TL [Mus musculus (hybrid C57CBAF1), long TL, and Mus spretus, short TL]. First, we compared relative TL in sperm samples from 5 age-matched males of each species by quantitative real-time PCR, with the numbers of telomere repeats being normalized, to the amount of DNA present in the sample (based on quantification of the Rn18S gene) by the comparative Ct method. Then, 1- and 2-cell embryos were produced by fertilizing Mus musculus oocytes with either Mus musculus or Mus spretus spermatozoa. The TL analysis in oocytes, zygotes, or 2-cell embryos was carried out by absolute quantification of telomere repeats by qPCR and normalized to the highest Ct observed value. Twenty to thirty samples per stage were analyzed, with each sample consisting in 2 matured oocytes, 2 zygotes, or one 2-cell embryo, to allow comparisons between stages. One-way ANOVA was used for statistical analysis. Mus spretus spermatozoa had significantly shorter telomeres than did Mus musculus (1.0 ± 0.1 v. 9.0 ± 1.5, respectively; P ≤ 0.01). The TL increased after fertilization from oocyte to zygote and 2-cell embryo stages in Mus musculus (1.0 ± 0.1, 1.5 ± 0.1, and 2.4 ± 0.2, respectively; P ≤ 0.01). In contrast, no differences were found in the TLs between the 3 stages in Mus spretus hybrids (oocyte: 1.0 ± 0.1; zygote: 1.0 ± 0.1; and 2-cell embryo: 1.0 ± 0.1), indicating that no elongation occurred after fertilization with spermatozoa with short telomeres. Herein, we demonstrated that before embryonic genome activation occurs, spermatozoa TL determines TL of the early embryo, suggesting that spermatozoon telomeres may act as recombination templates for early telomere lengthening right after syngamia.

scholarly journals RAD50 and RAD51 Define Two Pathways That Collaborate to Maintain Telomeres in the Absence of Telomerase

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Siyuan Le ◽  
J Kent Moore ◽  
James E Haber ◽  
Carol W Greider
Keyword(s):  
Cell Death ◽  
Telomere Length ◽  
Gene Conversion ◽  
De Novo ◽  
Dna Recombination ◽  
Telomere Maintenance ◽  
Triple Mutant ◽  
Yeast Telomerase ◽  
Telomere Lengthening

Abstract Telomere length is maintained by the de novo addition of telomere repeats by telomerase, yet recombination can elongate telomeres in the absence of telomerase. When the yeast telomerase RNA component, TLC1, is deleted, telomeres shorten and most cells die. However, gene conversion mediated by the RAD52 pathway allows telomere lengthening in rare survivor cells. To further investigate the role of recombination in telomere maintenance, we assayed telomere length and the ability to generate survivors in several isogenic DNA recombination mutants, including rad50, rad51, rad52, rad54, rad57, xrs2, and mre11. The rad51, rad52, rad54, and rad57 mutations increased the rate of cell death in the absence of TLC1. In contrast, although the rad50, xrs2, and mre11 strains initially had short telomeres, double mutants with tlc1 did not affect the rate of cell death, and survivors were generated at later times than tlc1 alone. While none of the double mutants of recombination genes and tlc1 (except rad52 tlc1) blocked the ability to generate survivors, a rad50 rad51 tlc1 triple mutant did not allow the generation of survivors. Thus RAD50 and RAD51 define two separate pathways that collaborate to allow cells to survive in the absence of telomerase.

scholarly journals The Rap1p-Telomere Complex Does Not Determine the Replicative Capacity of Telomerase-Deficient Yeast

2003 ◽  
Vol 23 (23) ◽  
pp. 8729-8739 ◽  
Author(s):  
Sarit Smolikov ◽  
Anat Krauskopf
Keyword(s):  
Telomere Length ◽  
Replicative Senescence ◽  
Budding Yeast ◽  
Kluyveromyces Lactis ◽  
Dna Binding Protein ◽  
Replicative Capacity ◽  
Telomeric Dna ◽  
Telomeric Repeats ◽  
Telomere Lengthening

ABSTRACT Telomeres are nucleoprotein structures that cap the ends of chromosomes and thereby protect their stability and integrity. In the presence of telomerase, the enzyme that synthesizes telomeric repeats, telomere length is controlled primarily by Rap1p, the budding yeast telomeric DNA binding protein which, through its C-terminal domain, nucleates a protein complex that limits telomere lengthening. In the absence of telomerase, telomeres shorten with every cell division, and eventually, cells enter replicative senescence. We have set out to identify the telomeric property that determines the replicative capacity of telomerase-deficient budding yeast. We show that in cells deficient for both telomerase and homologous recombination, replicative capacity is dependent on telomere length but not on the binding of Rap1p to the telomeric repeats. Strikingly, inhibition of Rap1p binding or truncation of the C-terminal tail of Rap1p in Kluyveromyces lactis and deletion of the Rap1p-recruited complex in Saccharomyces cerevisiae lead to a dramatic increase in replicative capacity. The study of the role of telomere binding proteins and telomere length on replicative capacity in yeast may have significant implications for our understanding of cellular senescence in higher organisms.

60 TELOMERE LENGTH DYNAMICS DURING BOVINE PREIMPLANTATION EMBRYO DEVELOPMENT

2012 ◽  
Vol 24 (1) ◽  
pp. 142
Author(s):  
C. de Frutos ◽  
P. Bermejo-Alvarez ◽  
D. Rizos ◽  
A. Gutierrez-Adan
Keyword(s):  
Developmental Stage ◽  
Telomere Length ◽  
Embryo Development ◽  
Relative Abundance ◽  
Preimplantation Embryo ◽  
Telomerase Activity ◽  
Alternative Mechanism ◽  
Cell Stage ◽  
Preimplantation Embryo Development ◽  
Early Embryos

The establishment of telomere length (TL) during embryogenesis determines telomere reserves in newborn mammals. However, limited information is available on TL dynamics during preimplantation in contrast to the extensive existing data on telomerase activity in germ cells and embryogenesis. Telomerase activity is high in the male germ line, low or absent in oocytes and early stage embryos and high in blastocysts (Bl). Mechanisms allowing early embryos to reset TL remain poorly understood. The documented telomere lengthening at the morula/Bl transition in mice and bovines is dependent on telomerase activity. A recombinant-based mechanism termed alternative lengthening of telomeres (ALT) has been postulated to be responsible for the lengthening of telomeres in early embryos. The aims of the present study were to analyse the telomere dynamics during preimplantation embryo development in 2 species of known different TL: mice and bovines and the relative expression of 2 components of telomerase [telomerase reverse transcriptase (Tert; the key factor that controls the activity of the telomerase) and telomerase RNA component (Terc)]. Twenty samples for each developmental stage with an equivalent number of cells (matured oocytes/zygotes: 8 and 32; 2-cell embryos: 4 and 16; 4-cell embryos: 2 and 8; 8-cell embryos: 1 and 4; 16-cell embryos: 2 only for bovine; morulae: 1 and 1; and Bl: 1 and 1 for mice and bovines, respectively) were analysed for relative TL measurement using the real-time quantitative PCR method described previously (Bermejo-Alvarez et al. 2008 Physiol. Genomics 32, 264272). For measuring the mRNA, 3 groups of 10 oocytes/embryos for each developmental stage were used. Data were analysed by 1-way ANOVA. In mice, matured oocytes had the shortest telomeres of all stages examined (P < 0.01); a slight increase up to the 4-cell stage and a decrease at the 8-cell and morula stages was noted (P < 0.05), while a marked increase was observed in Bl, as expected (P < 0.01). In contrast, bovine matured oocytes had longer telomeres than zygotes and this length gradually decreased up to the 4-cell stage and increased again at the 16-cell stage (P < 0.05). Then, telomeres shortened at the morula stage (P < 0.05) and a significant increase was observed at the Bl stage like in mice (P < 0.01). The relative abundance of mTerc increased throughout development with a marked up-regulation at the morula and Bl stages (P < 0.01). On the other hand, the relative abundance of mTert was significantly higher in the mature oocytes and zygotes compared to later stages (P < 0.01); however, it should be noted that there was a gradual increase from the 2-cell stage up to Bl. In conclusion, in contrast to mice, bovine oocytes have longer telomeres than zygotes. Knowing that the telomerase activity is low or absent until the Bl stage (indicated by the low expression of Tert), the TL increase detected in 16-cell bovine embryos indicates an alternative mechanism for telomere elongation during early development, like that observed in mice. Understanding how telomeres reset during early embryo development has implications for the study of stem cells and regenerative biology.

scholarly journals The Role of Rif1 in telomere length regulation is separable from its role in origin firing

2020 ◽  
Author(s):  
Calla B. Shubin ◽  
Carol W. Greider
Keyword(s):  
Telomere Length ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Origin Firing ◽  
Replication Complex ◽  
Telomere Elongation ◽  
Length Regulation ◽  
Telomere Length Regulation ◽  
Telomere Lengthening

AbstractTo examine the established link between DNA replication and telomere length, we tested whether firing of telomeric origins would cause telomere lengthening. We found that RIF1 mutants that block Protein Phosphatase 1 (PP1) binding activated telomeric origins but did not elongate telomeres. In a second approach, we found overexpression of ΔN-Dbf4 and Cdc7 increased DDK activity and activated telomeric origins, yet telomere length was unchanged. We tested a third mechanism to activate origins using the sld3-A mcm5-bob1 mutant that deregulates the pre-replication complex, and again saw no change in telomere length. Finally, we tested whether mutations in RIF1 that cause telomere elongation would affect origin firing. We found that neither rif1-Δ1322 nor rif1HOOK affected firing of telomeric origins. We conclude that telomeric origin firing does not cause telomere elongation, and the role of Rif1 in regulating origin firing is separable from its role in regulating telomere length.

scholarly journals The role of Rif1 in telomere length regulation is separable from its role in origin firing

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Calla B Shubin ◽  
Carol W Greider
Keyword(s):  
Telomere Length ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Origin Firing ◽  
Replication Complex ◽  
Telomere Elongation ◽  
Length Regulation ◽  
Telomere Length Regulation ◽  
Telomere Lengthening

To examine the established link between DNA replication and telomere length, we tested whether firing of telomeric origins would cause telomere lengthening. We found that RIF1 mutants that block Protein Phosphatase 1 (PP1) binding activated telomeric origins but did not elongate telomeres. In a second approach, we found overexpression of ∆N-Dbf4 and Cdc7 increased DDK activity and activated telomeric origins, yet telomere length was unchanged. We tested a third mechanism to activate origins using the sld3-A mcm5-bob1 mutant that de-regulates the pre-replication complex, and again saw no change in telomere length. Finally, we tested whether mutations in RIF1 that cause telomere elongation would affect origin firing. We found that neither rif1-∆1322 nor rif1HOOK affected firing of telomeric origins. We conclude that telomeric origin firing does not cause telomere elongation, and the role of Rif1 in regulating origin firing is separable from its role in regulating telomere length.

Autophagy and ubiquitin-mediated proteolysis may not be involved in the degradation of spermatozoon mitochondria in mouse and porcine early embryos

Zygote ◽  
2014 ◽  
Vol 24 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Yong-Xun Jin ◽  
Zhong Zheng ◽  
Xian-Feng Yu ◽  
Jia-Bao Zhang ◽  
Suk Namgoong ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Light Chain ◽  
Positive Control ◽  
Blastocyst Stage ◽  
Cell Stage ◽  
Intracytoplasmic Injection ◽  
Early Embryos ◽  
Morula Stage ◽  
Zygote Stage

SummaryThe mitochondrial genome is maternally inherited in animals, despite the fact that paternal mitochondria enter oocytes during fertilization. Autophagy and ubiquitin-mediated degradation are responsible for the elimination of paternal mitochondria in Caenorhabditis elegans; however, the involvement of these two processes in the degradation of paternal mitochondria in mammals is not well understood. We investigated the localization patterns of light chain 3 (LC3) and ubiquitin in mouse and porcine embryos during preimplantation development. We found that LC3 and ubiquitin localized to the spermatozoon midpiece at 3 h post-fertilization, and that both proteins were colocalized with paternal mitochondria and removed upon fertilization during the 4-cell stage in mouse and the zygote stage in porcine embryos. Sporadic paternal mitochondria were present beyond the morula stage in the mouse, and paternal mitochondria were restricted to one blastomere of 4-cell embryos. An autophagy inhibitor, 3-methyladenine (3-MA), did not affect the distribution of paternal mitochondria compared with the positive control, while an autophagy inducer, rapamycin, accelerated the removal of paternal mitochondria compared with the control. After the intracytoplasmic injection of intact spermatozoon into mouse oocytes, LC3 and ubiquitin localized to the spermatozoon midpiece, but remnants of undegraded paternal mitochondria were retained until the blastocyst stage. Our results show that paternal mitochondria colocalize with autophagy receptors and ubiquitin and are removed after in vitro fertilization, but some remnants of sperm mitochondrial sheath may persist up to morula stage after intracytoplasmic spermatozoon injection (ICSI).

scholarly journals Telomere Length Reprogramming in Embryos and Stem Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Keri Kalmbach ◽  
LeRoy G. Robinson ◽  
Fang Wang ◽  
Lin Liu ◽  
David Keefe
Keyword(s):  
Stem Cells ◽  
Telomere Length ◽  
Genetic Mutations ◽  
Subsequent Generation ◽  
Linear Chromosome ◽  
Age Related ◽  
Early Embryos

Telomeres protect and cap linear chromosome ends, yet these genomic buffers erode over an organism’s lifespan. Short telomeres have been associated with many age-related conditions in humans, and genetic mutations resulting in short telomeres in humans manifest as syndromes of precocious aging. In women, telomere length limits a fertilized egg’s capacity to develop into a healthy embryo. Thus, telomere length must be reset with each subsequent generation. Although telomerase is purportedly responsible for restoring telomere DNA, recent studies have elucidated the role of alternative telomeres lengthening mechanisms in the reprogramming of early embryos and stem cells, which we review here.

scholarly journals The telomere length landscape of prostate cancer

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julie Livingstone ◽  
Yu-Jia Shiah ◽  
Takafumi N. Yamaguchi ◽  
Lawrence E. Heisler ◽  
Vincent Huang ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Telomere Length ◽  
Localized Prostate Cancer ◽  
Structural Variants ◽  
Single Nucleotide Variants ◽  
Single Nucleotide ◽  
Genomic Features ◽  
Multi Level ◽  
Telomere Lengthening

AbstractReplicative immortality is a hallmark of cancer, and can be achieved through telomere lengthening and maintenance. Although the role of telomere length in cancer has been well studied, its association to genomic features is less well known. Here, we report the telomere lengths of 392 localized prostate cancer tumours and characterize their relationship to genomic, transcriptomic and proteomic features. Shorter tumour telomere lengths are associated with elevated genomic instability, including single-nucleotide variants, indels and structural variants. Genes involved in cell proliferation and signaling are correlated with tumour telomere length at all levels of the central dogma. Telomere length is also associated with multiple clinical features of a tumour. Longer telomere lengths in non-tumour samples are associated with a lower rate of biochemical relapse. In summary, we describe the multi-level integration of telomere length, genomics, transcriptomics and proteomics in localized prostate cancer.

64 SIN3 transcription regulator family member A regulates porcine early embryonic development by modulating CCNB1 expression

2021 ◽  
Vol 33 (2) ◽  
pp. 139
Author(s):  
L. Luo ◽  
Y. Dang ◽  
Y. Shi ◽  
P. Zhao ◽  
Y. Zhang ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Family Member ◽  
Natural Science ◽  
Early Embryonic Development ◽  
Cell Stage ◽  
Transcription Regulator ◽  
Early Embryos ◽  
Similar Phenotype ◽  
Blastocyst Rate

SIN3 transcription regulator family member A (SIN3A) is the central scaffold protein of the SIN3/HDAC (histone deacetylase) transcriptional repressor complex. We previously found that SIN3A participates in the mouse pre-implantation development by finetuning HDAC1 expression. However, it remains unresolved whether this functional significance of SIN3A is conserved in other mammals. The objective of this work was thus to characterise the expression profiles and the functional role of SIN3A in pre-implantation development using non-rodent animal models. RNA sequencing results show that a large amount of SIN3A mRNA is present in oocytes and early embryos before embryonic genome activation and a low amount thereafter, suggesting a maternal origin of SIN3A in all species examined. Interestingly, immunofluorescence data show that SIN3A protein level peaks at the 4-cell stage in pigs compared with the morula stage in cattle, suggesting a differential role of SIN3A among species. To explore the function of SIN3A in early embryonic development, we used a short interfering (si)RNA-mediated knockdown approach in porcine parthenogenetic activated (PA) embryos. Immunocytochemical analysis showed that SIN3A levels were diminished ∼80% compared with nonspecific siRNA (NC) injected control (n=3). To monitor the developmental potential of embryo depleted of SIN3A, we injected SIN3A-siRNA into MII stage oocytes, followed by parthenogenetic activation, and percent cleavage and blastocyst formation were recorded. We found that SIN3A knockdown (KD) did not affect the cleavage rate (NC vs. KD, 83.63±3.63% vs. 80.08±4.66%, n=5), but significantly reduced blastocyst rate compared with the NC group (NC vs. KD, 36.64±4.28% vs. 6.33±3.12%, n=5). Specifically, SIN3A depletion in early embryos causes developmental arrest at 2-cell stage in pigs but does not affect early embryonic development in bovines. In contrast with mouse data, SIN3A depletion results in only a slight decrease and even no difference in HDAC1 expression in porcine and bovine early embryos, respectively. In addition, HDAC1 knockdown does not cause 2-cell block but leads to a reduced blastocyst rate, suggesting that the effect of SIN3A depletion on porcine early embryos is independent of HDAC1. RNA-Seq analysis was used to compare the global transcript content between NC and KD 2-cell embryos. A total of 23 genes (14 upregulated and 9 downregulated) had undergone significant changes. Interestingly, cyclin B1 (CCNB1) ranked second among downregulated genes. To test whether knockdown of CCNB1 would display a similar phenotype in porcine early embryos, we injected CCNB1-siRNA into pronuclear stage. CCNB1 KD resulted in a similar phenotype as SIN3A depletion. Injection of exogenous CCNB1 mRNA into SIN3A-depleted embryos could partly rescue embryonic development. In conclusion, our results indicate SIN3A plays an essential role in porcine early embryonic development, probably involving the regulation of CCNB1 expression. This work was funded by National Natural Science Foundation of China, the Anhui Provincial Natural Science Foundation and China Postdoctoral Science Foundation.

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