Biology subjects

Viveiros, J. M.

Publications and source records attributed to Viveiros, J. M..

3 recordsLinked to original sources

bioRxiv2022

Emergent dynamics of adult stem cell lineages from single nucleus and single cell RNA-Seq of Drosophila testes

Proper differentiation of sperm from germline stem cells, essential for production of the next generation, requires dramatic changes in gene expression that drive remodeling of almost all cellular components, from chromatin to organelles to cell shape itself. Here we provide a single nucleus and single cell RNA-seq resource covering all of spermatogenesis in Drosophila starting from in-depth analysis of adult testis single nucleus RNA-seq (snRNA-seq) data from the Fly Cell Atlas (FCA) study (Li et al., 2022). With over 44,000 nuclei and 6,000 cells analyzed, the data provide identification of rare cell types, mapping of intermediate steps in differentiation, and the potential to identify new factors impacting fertility or controlling differentiation of germline and supporting somatic cells. We justify assignment of key germline and somatic cell types using combinations of known markers, in situ hybridization, and analysis of extant protein traps. Comparison of single cell and single nucleus datasets proved particularly revealing of dynamic developmental transitions in germline differentiation. To complement the web-based portals for data analysis hosted by the FCA, we provide datasets compatible with commonly used software such as Seurat and Monocle. The foundation provided here will enable communities studying spermatogenesis to interrogate the datasets to identify candidate genes to test for function in vivo.

developmental biology↗

bioRxiv2019

Extramacrochaete promotes branch and bouton number via the sequestration of Daughterless in the cytoplasm of neurons.

The class I basic Helix Loop Helix (bHLH) proteins are highly conserved transcription factors that are ubiquitously expressed. A wealth of literature on class I bHLH proteins have shown that these proteins must homodimerize or heterodimerize with tissue specific HLH proteins in order to bind DNA at E box (CANNTG) consensus sequences to control tissue specific transcription. Due to its ubiquitous expression, class I bHLH proteins are also extensively regulated post-translationally, mostly through dimerization. Previously, we reported that in addition to its role in promoting neurogenesis, the class I bHLH protein Daughterless also functions in mature neurons to restrict axon branching and synapse number. Here, we show that part of the molecular logic that specifies how Daughterless functions in neurogenesis is also conserved in neurons. We show that the type V HLH protein Extramacrochaete binds to and represses Daughterless function by sequestering Daughterless to the cytoplasm. This work provides initial insights into the mechanisms underlying the function of Daughterless and Extramacrochatae in neurons while providing a novel understanding of how Extramacrochaetae functions to restricts Daughterless activity within the cell.

neuroscience↗

bioRxiv2018

The Drosophila chromodomain protein Kismet activates steroid hormone receptor transcription to govern axon pruning and memory in vivo.

Axon pruning is critical for the proper synapse elimination required for sculpting precise neural circuits. Though axon pruning has been described in the literature for decades, relatively little is known about the molecular and cellular mechanisms that govern axon pruning in vivo. Here, we show that the epigenetic reader Kismet (Kis) binds to cisregulatory elements of the steroid hormone receptor Ecdysone Receptor (EcR) gene in Drosophila neurons. Kis is required to activate EcR transcription at these elements and promote H3K36 di- and tri-methylation and H4K16 acetylation. We show that exogenous EcR can rescue axon pruning and memory defects associated with loss of Kis, and that the histone deacetylase inhibitor SAHA can rescue these phenotypes. EcR protein abundance is a cell-autonomous, rate-limiting step required to initiate axon pruning in Drosophila, and our data suggests that this step is under epigenetic control.\n\nHighlights (bullet points up to 4)O_LIThe chromodomain reader Kismet activates transcription of the steroid hormone receptor EcR-B1 in the Drosophila to initiate developmental axon pruning.\nC_LIO_LIKismet promotes H3K36 di- and tri-methylation and H4K16 acetylation at the EcR locus and upstream cis-regulatory sites.\nC_LIO_LIAxon pruning and memory defects associated with loss of Kismet are significantly rescued by general HDAC inhibition.\nC_LI

neuroscience↗