Biology subjects

Ugolini, M.

Publications and source records attributed to Ugolini, M..

4 recordsLinked to original sources

bioRxiv2024

The Aging Synapse: An Integrated Proteomic And Transcriptomic Analysis

An important hallmark of aging is the loss of proteostasis, which can lead to the formation of protein aggregates and mitochondrial dysfunction in neurons. Although it is well known that protein synthesis is finely regulated in the brain, especially at synapses, where mRNAs are locally translated in activity-dependent manner, little is known as to the changes in the synaptic proteome and transcriptome during aging. Therefore, this work aims to elucidate the relationship between transcriptome and proteome at soma and synaptic level during aging. Proteomic and transcriptomic data analysis reveal that, in young animals, proteins and transcripts are correlated and synaptic regulation is driven by changes in the soma. During aging, there is a decoupling between transcripts and proteins and between somatic and synaptic compartments. Furthermore, soma-synapse gradient of ribosomal genes changes upon aging, i.e. ribosomal transcripts are less abundant and ribosomal proteins are more abundant in synaptic compartment of old mice with respect to younglings. Additionally, transcriptomics data highlight a difference in the splicing of certain synaptic mRNA with aging. Taken together, our data provide a valuable resource for the study of the aging synapse.

neuroscience↗

bioRxiv2022

Targeted disruption of transcription bodies causes widespread activation of transcription

The localization of transcriptional activity in specialized transcription bodies is a hallmark of gene expression in eukaryotic cells. It remains unclear, however, if and how they affect gene expression. Here, we disrupted the formation of two prominent endogenous transcription bodies that mark the onset of zygotic transcription in zebrafish embryos and analysed the effect on gene expression using enriched SLAM-Seq and live-cell imaging. We find that the disruption of transcription bodies results in downregulation of hundreds of genes, providing experimental support for a model in which transcription bodies increase the efficiency of transcription. We also find that a significant number of genes are upregulated, counter to the suggested stimulatory effect of transcription bodies. These upregulated genes have accessible chromatin and are poised to be transcribed in the presence of the two transcription bodies, but they do not go into elongation. Live-cell imaging shows that the disruption of the two large transcription bodies enables these poised genes to be transcribed in ectopic transcription bodies, suggesting that the large transcription bodies sequester a pause release factor. Supporting this hypothesis, we find that CDK9, the kinase that releases paused polymerase II, is highly enriched in the two large transcription bodies. Importantly, overexpression of CDK9 in wild type embryos results in the formation of ectopic transcription bodies and thus phenocopies the removal of the two large transcription bodies. Taken together, our results show that transcription bodies regulate transcription genome-wide: the accumulation of transcriptional machinery creates a favourable environment for transcription locally, while depriving genes elsewhere in the nucleus from the same machinery.

cell biology↗

bioRxiv2022

Nanog organizes transcription bodies

The localization of transcriptional activity in specialized transcription bodies is a hallmark of gene expression in eukaryotic cells. How proteins of the transcriptional machinery come together to form such bodies, however, is unclear. Here, we take advantage of two large, isolated, and long-lived transcription bodies that reproducibly form during early zebrafish embryogenesis, to characterize the dynamics of transcription body formation. Once formed, these transcription bodies are enriched for initiating and elongating RNA polymerase II, as well as the transcription factors Nanog and Sox19b. Analyzing the events leading up to transcription, we find that Nanog and Sox19b cluster prior to transcription, and independently of RNA accumulation. The clustering of transcription factors is sequential; Nanog clusters first, and this is required for the clustering of Sox19b and the initiation of transcription. Mutant analysis revealed that both the DNA-binding domain, as well as one of the two intrinsically disordered regions of Nanog are required to organize the two bodies of transcriptional activity. Taken together, our data suggests that the clustering of transcription factors dictates the formation of transcription bodies. HIGHLIGHTSO_LITranscription factors cluster prior to, and independently of transcription C_LIO_LINanog organizes transcription bodies: it is required for the clustering of Sox19b as well as RNA polymerase II C_LIO_LIThis organizing activity requires its DNA binding domain as well as one of its intrinsically disordered regions C_LIO_LITranscription elongation results in the disassembly of transcription factor clusters C_LI

cell biology↗

bioRxiv2019

Mitohormetic effects of rotenone drastically depend on age

Hormesis refers to a biphasic intensity-dependent response to stressors where low-intensity or short-duration exposure to potentially noxious stressors induces long-lasting adaptations that have positive physiological effects [1]. It was proposed that life-extending interventions, such as calorie restriction, retard aging via their hormetic action [2]. More recently, it was shown that a transient burst of reactive oxygen species is required to induce the effects of calorie restriction [3], physical exercise [4], inhibition of the insulin/IGF-I pathway [5] and metformin [6]. We have previously shown that partial inhibition of complex I of the respiratory chain by a low dose of the poison rotenone (ROT) administered in middle age increases the lifespan and reverts the transcriptomic signature of aging in a vertebrate species [7], an example of a hormetic effect. Here, we asked whether ROT treatment started at young age induces larger effects on life-span and transcriptome.

pharmacology and toxicology↗