Biology subjects

Klutstein, M.

Publications and source records attributed to Klutstein, M..

4 recordsLinked to original sources

bioRxiv2022

2-hydroxyglutarate controls centromere and heterochromatin conformation and function in the male germline

2-hydroxyglutarate (2HG) is recognized as an epigenetic regulator in cancer and some transient biological processes. Of all organs, the testis harbors the highest baseline physiological levels of 2HG, yet its putative functions in germ cell biology are unknown. Here we show that 2HG is generated in specific stages of spermatogenesis by the testis specific lactate dehydrogenase C (LDHC), beginning at the last stages of prophase I. Unexpectedly LDHC enters nuclei and concentrates in centromeres. LDHC-generated L-2HG controls centromere condensation and pericentromeric heterochromatin organization through multiple effects including clustering of chromocenters, centromere and chromocenter condensation and expression of satellite RNAs. These effects are rapid and specific to L but not D-2HG. In vivo depletion of L-2HG causes centromere malfunction and activation of the spindle assembly checkpoint. Our findings reveal that 2HG can directly affect centromere and pericentromeric heterochromatin conformation and function and is necessary for licensing chromosome segregation.

cell biology↗

bioRxiv2020

Loss of heterochromatin and retrotransposon silencing constitute an early phase in oocyte aging

Mammalian oocyte quality reduces with female age. A well-studied aspect of this deterioration is an age-associated rise in oocyte aneuploidy. We show that prior to the occurrence of significant aneuploidy (at the age of 9 months in mouse females), epigenetic changes occur and impact oocyte quality and maturation ability. At this age- we observe a reduction in heterochromatin marks in mouse oocytes. This decrease is apparent in both constitutive heterochromatin and facultative heterochromatin marks but is absent in active euchromatic marks which remain constant. A decrease of heterochromatin marks with age is also observed in human GV oocytes from IVF treatments. Heterochromatin loss with age is associated with an elevation in retrotransposon RNA transcription and processing, an elevation in retrotransposon protein expression, elevation in DNA repair proteins nuclear localization and oocyte maturation defects. Artificial inhibition of the heterochromatin machinery in young oocytes causes an elevation in retrotransposon expression and processing and oocyte maturation defects. Collectively, our work demonstrates an early stage of oocyte aging, characterized by the loss of heterochromatin associated chromatin marks and activation of retrotransposons which cause DNA damage and impair oocyte maturation. We hypothesize that this heterochromatin loss serves as an oocyte associated "epigenetic clock" and is exploited by the cell as an oocyte QC mechanism. One Sentence SummaryOocyte aging includes an early pre-aneuploidy phase when loss of repressive chromatin marks occurs as well as retrotransposon activation and egg maturation defects.

cell biology↗

bioRxiv2019

Meiosis and Kinetochore genes are used by cancer cells as genome destabilizers and transformation catalysts

Cancer cells have an altered transcriptome which contributes to their altered behaviors compared to normal cells. Indeed, many tumors express high levels of genes participating in meiosis or kinetochore biology, but the role of this high expression has not been fully elucidated. In this study we explore the relationship between this overexpression and genome instability and transformation capabilities of cancer cells. For this, we obtained expression data from 5 different cancer types which were analyzed using computational information-theoretic analysis. We were able to show that highly expressed meiotic/kinetochore genes were enriched in the altered gene expression subnetworks characterizing unstable cancer types with high chromosome instability (CIN). However, altered subnetworks found in the cancers with low CIN did not include meiotic and kinetochore genes. Representative gene candidates, found by the analysis to be correlated with a CIN phenotype, were further explored by transfecting genomically-stable (HCT116) and unstable (MCF7) cancer cell lines with vectors overexpressing those genes. This overexpression resulted in an increase in the numbers of abnormal cell divisions and defective spindle formations and in increased transformation properties in stable cancer HCT116 cells. Interestingly, the same properties were less affected by the overexpressed genes in the unstable MCF7 cancer cells. Our results indicate that overexpression of both meiosis and kinetochore genes is capable of driving genomic instability and cancer progression.

cancer biology↗

bioRxiv2019

Isolation and characterization of live yeast cells from ancient vessels as a tool in bio-archeology

Ancient fermented food has been studied based on recipes, residue analysis and ancient-DNA techniques and reconstructed using modern domesticated yeast. Here, we present a novel approach. We hypothesize that enriched yeast populations in fermented beverages could have become the dominant species in storage vessels and the descendants of these yeast could be isolated and studied long after. To this end, using a pipeline of yeast isolation from clay vessels developed here, we screened for yeast cells in beverage-related and non-related ancient vessels and sediments, from several archeological sites. We found that yeast cells could be successfully isolated specifically from clay containers of fermented beverages. Genomic analysis revealed that these yeast are similar to those found in traditional African beverages. Phenotypically, they grow similar to modern-beer producing yeast. Both strongly suggesting that they are descendants of the original fermenting yeast. These findings provide modern microorganisms as a new tool in bio-archeology. ImportanceSo far, most of the study of ancient organisms was based mainly on the analysis of ancient DNA. Here we show that it is possible to isolate and study microorganisms, yeast in this case, from thousands of years old clay vessels, used for fermentation. We demonstrate that it is highly likely that these cells are descendants of the original yeast strains which participated in the fermentation process and were absorbed into the pottery vessels. Moreover, we characterize the isolated yeast their genome and the beer they produce. These results open new and exciting avenues in the study of domesticated microorganisms and contribute significantly to the fields of bio and experimental -archeology that aims to reconstruct ancient artifacts and products.

ecology↗