Biology subjects

Mazzetto, M.

Publications and source records attributed to Mazzetto, M..

6 recordsLinked to original sources

bioRxiv2026

Population-scale Y chromosome assemblies reveal recurrent remodeling within constrained architectures

The human Y chromosome is among the most structurally dynamic chromosomes in the human genome, yet much of its diversity remains unresolved because of extensive palindromes, ampliconic gene families, satellite-rich heterochromatin and large segmental duplications. What remained unclear was how these diverse forms of variation fit together across the full chromosome, how often similar structures recur in different lineages, and which aspects of organization remain constrained despite rapid sequence turnover. Here, we generated and analyzed 142 nearly complete human Y chromosome assemblies from 17 major haplogroups spanning approximately 180,000 years of evolution, creating a population-scale resource for studying Y chromosome biology and diversity. These assemblies show that structural change on the Y chromosome is recurrent but constrained, even in its most repetitive regions. In the fertility-associated azoospermia factor c (AZFc) region, recurrent inversions, deletions, and complex rearrangements generate a limited repertoire of structural haplotypes. Multicopy ampliconic gene families follow distinct evolutionary paths: DAZ paralogues differ in structural constraint, RBMY evolves within a modular array, and TSPY copy number varies mainly through local expansion and contraction. The centromere and Yq12 heterochromatin vary greatly in size but retain a stable higher-order organization, including a single hypomethylated centromeric core and conserved Yq12 repeat composition and orientation. Methylation across palindromic and ampliconic regions is likewise structured by repeat class, copy order and local architecture. Together, these results provide a population-scale resource for the human Y chromosome and show that its rapid structural evolution is repeatedly funneled into a limited set of architectural outcomes.

genomics↗

bioRxiv2026

Identification of germline chromatin modifying factors that influence zygotic transcription activation in C. elegans

Precise control of the onset of transcription in post-fertilization embryos, often termed zygotic genome activation (ZGA), is essential to coordinate cell divisions and fate decisions to ensure proper development of the body plan. Maternally-contributed proteins and RNAs deposited in the zygote play an important role in ZGA, as does chromatin organization in pronuclei, yet the mechanisms by which parental germ cells anticipate the requirements for the first stages of ZGA is still not well understood. Using C. elegans as a model to study the epigenetic contributions from parental germ cells during the oocyte-to-embryo transition (OET), we previously demonstrated that histone modifications might act in germ cells to control ZGA. Here, we develop a novel assay to specifically track nascent transcription in gonads and embryos, which we use to identify chromatin regulatory factors acting in the germline that are responsible for subsequently promoting or inhibiting transcription during OET. This approach identifies regulation of both H3K4 methylation and H3K36 methylation in the parental germline as important contributors to successful ZGA and subsequent embryogenesis, and sets the stage for further mechanistic dissection of this critical developmental window upon the formation of a new organism.

developmental biology↗

bioRxiv2025

SPINK1-COL18A1 Crosstalk Shapes Epigenome and Drives Cancer Stemness in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a devastating cancer with an increasing incidence and extremely dismal prognosis. Discovery and mechanistic understanding of the genetic and epigenetic drivers of PDAC is therefore of critical importance. Here, we uncover serine protease inhibitor Kazal type 1 (SPINK1) as a putative determinant of clinical progression and demonstrate that it can have a non-canonical function as a regulator of epigenomic states of PDAC cells and associated extensive changes in gene expression. We show that SPINK1 expression, which varies in PDAC, is associated with key aggressive phenotypic cancer states and is correlated with the expression of stemness markers both in vitro and in patient samples. Mechanistically, our results strongly suggest that SPINK1 acts through a new signaling axis, by interacting with COL18A1 in the Golgi apparatus, promoting endostatin release and eventually inducing extensive histone H3 modifications. These results reveal a new function of SPINK1 in PDAC and suggest a potential therapeutic route to combat PDAC aggressiveness by targeting the SPINK1-COL18A1-endostatin signaling.

cancer biology↗

bioRxiv2023

Transcriptome analysis of different strains of the turquoise killifish Nothobranchius furzeri identifies signatures associated with heritable lifespan differences

The killifish Nothobranchius furzeri is the shortest-lived vertebrate model organism and is characterized by laboratory strains differing in lifespan by more than a factor of two. The genetic architecture underlying this difference is complex and the pathways responsive remain elusive. We performed an analysis in N. furzeri of public transcritomic datasets comprehensive of four different tissues and one embryonic stage in two strains: the shorter-lived GRZ and the longer-lived MZM0410. Remarkably, the two strains differ in their transcriptome profile already at the embryonic stage. The short-lived strain GRZ shows an anticipated aging profile consistently in all tissues investigated, with differences in expression of aging-related genes detected already at sexual maturity. In addition, analysis of a longitudinal dataset revealed that genes whose expression is prognostic of longer lifespan at the individual level are also differentially expressed between strains at an early adult age, suggesting antagonistic pleiotropism.

genomics↗

bioRxiv2023

Distribution and dynamics of chromatin states in the C. elegans germ line

Chromatin organization in the C. elegans germ line is tightly regulated and critical for germ cell differentiation. While certain germline epigenetic regulatory mechanisms have been identified, how they influence chromatin structure and ultimately gene expression remain unclear, in part because most genomic studies have focused on data collected from whole worms. We therefore analyzed publicly available histone modification and chromatin accessibility data from isolated undifferentiated germ nuclei to define chromatin states. We then correlated these states with overall transcript abundance, spatio-temporal expression patterns, and the function of small RNA pathways. Because the essential role of the germ line is to transmit genetic information to the next generation and establish gene expression in the early embryo, we compared epigenetic and transcriptomic profiles from undifferentiated germ cells, oocytes, and embryos to define the epigenetic changes during this developmental transition. The active histone modification H3K4me3 exhibits particularly dynamic remodeling as germ cells differentiate into oocytes. Our results highlight the dynamism of the chromatin landscape in germ cells, and provide a resource for future investigation into epigenetic regulatory mechanisms.

genomics↗

bioRxiv2019

Reduced proteasome activity in the aging brain results in ribosome stoichiometry loss and aggregation

A progressive loss of protein homeostasis is characteristic of aging and a driver of neurodegeneration. To investigate this process quantitatively, we characterized proteome dynamics during brain aging in the short-lived vertebrate Nothobranchius furzeri combining transcriptomics and proteomics. We detected a progressive reduction in the correlation between protein and mRNA, mainly due to post-transcriptional mechanisms that account for over 40% of the age-regulated proteins. These changes cause a progressive loss of stoichiometry in several protein complexes, including ribosomes, which show impaired assembly / dis-assembly and are enriched in protein aggregates in old brains. Mechanistically, we show that reduction of proteasome activity is an early event during brain aging and is sufficient to induce proteomic signatures of aging and loss of stoichiometry in vivo. Using longitudinal transcriptomic data, we show that the magnitude of early life decline in proteasome levels is the major risk factor for mortality. Our work defines causative events in the aging process that can be targeted to prevent loss of protein homeostasis and delay the onset of age-related neurodegeneration. HighlightsO_LIProgressive loss of stoichiometry affects multiple protein complexes C_LIO_LIRibosomes aggregate in old brains C_LIO_LIPartial reduction of proteasome activity is sufficient to induce loss of stoichiometry C_LIO_LIReduced proteasome levels are a major risk factor for early death in killifish C_LI

systems biology↗