Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2020.11.18.374223

Isolation of nuclei and downstream processing of cell-type-specific nuclei from micro-dissected mouse brain regions - techniques and caveats.

Chongtham, M. C.·Todorov, H.·Wettschereck, J.·Gerber, S.·Winter, J.
View original source ↗Export metadata ↓

Abstract

The mammalian brain consists of several structurally and functionally distinct regions equipped with an equally complex cell-type system. Due to its relevance in uncovering disease mechanisms, the study of cell-type-specific molecular signatures of different brain regions has increased. The rapid evolution of newer and cheaper sequencing techniques has also boosted the interest in cell-type-specific epigenetic studies. In fact, the nucleus holds most of the cells epigenetic information and is quite resistant to tissue dissociation processes as compared to cells. As such, nuclei are continually preferred over cells for epigenetic studies. However, the isolation of nuclei from cells is still a biochemically complex process, with every step affecting downstream results. Therefore, it is necessary to use protocols that fit the experimental design to yield nuclei of high quality and quantity. However, the current protocols are not suitable for nuclei isolation of small volumes of micro-dissected brain regions from individual mouse brains. Additionally, the caveats associated with centrifugation steps of nuclei extraction and the effects of different buffers have not been thoroughly investigated. Therefore, in this study, we describe an iodixanol based density gradient ultracentrifugation protocol suitable for micro-dissected brain regions from individual mice using ArccreERT2 (TG/WT).R26CAG-Sun1-sfGFP-Myc (M/WT or M/M). This mouse model shows sfGFP expression (sfGFP+) in the nuclear membrane of specific stimulus activated cells, thereby providing a good basis for the study - nuclei isolation and separation of cell-type-specific nuclei. The study also introduces new tools for rapid visualization and assessment of quality and quantity of nascent extracted nuclei. These tools were then used to examine critical morphological features of nuclei derived from different centrifugation methods and the use of different buffers to uncover underlying effects. Finally, to obtain cell-type-specific nuclei (sfGFP+ nuclei) from the isolated nuclei pool of high viscosity, an optimized protocol for fluorescence activated nuclei sorting (FANS) was established to speed up sorting. Additionally, we present a 1% PFA protocol for fixation of isolated nuclei for long term microscopic visualization.

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Chongtham, M. C., Todorov, H., Wettschereck, J., Gerber, S., Winter, J.. 2020-11-18. Isolation of nuclei and downstream processing of cell-type-specific nuclei from micro-dissected mouse brain regions - techniques and caveats.. https://doi.org/10.1101/2020.11.18.374223

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Functional characterization of Rho GTPase activating proteins SYDE1 and SYDE2

The human genome encodes more than 60 proteins containing Rho GTPase activating protein (RhoGAP) domains, many of which remain understudied with respect to their target specificity and biological roles. SYDE1 and SYDE2 are two such orphan RhoGAPs, for which there are few studies characterizing their biochemical and cellular functions and conflicting reports identifying their cognate GTPases. We previously identified SYDE1 and SYDE2 in a screen for substrates of the c-Jun N-terminal kinases. Here, we show that SYDE1 and SYDE2 are preferentially phosphorylated by JNK1 relative to other mitogen-activated protein kinases (MAPKs) at sites proximal to a kinase docking region. Purified SYDE1 and SYDE2 are shown to have significant catalytic GAP activity toward RhoA, Rac1, and Cdc42. However, neither up- nor down-regulation of SYDE1/2 expression leads to detectable changes in bulk GTP loading of any of these GTPases. Nevertheless, we demonstrate that SYDE1 and SYDE2, in a partially GAP-dependent manner, increase cell spreading and number of focal adhesions, and promote more directionally persistent migration in HEK293 cells. Together, these findings establish SYDE1 and SYDE2 as robust JNK substrates with catalytic activity toward a set of Rho GTPases and reveal basic functions of SYDE1 and SYDE2 in regulating cell morphology, adhesion, and migration.

cell biology↗
bioRxiv2026

The filopodial scaffold polyphosphate dictates cell adhesion-versus-invasion decisions

Inorganic polyphosphate (polyP) is an ancient polymer conserved across all life, serving cell type and location specific functions in every major compartment. Yet its role at the plasma membrane, where it accumulates to peak levels in many primary cells, is largely unknown. Here we identify polyP as a stabilizing component of filopodia, actin based membrane protrusions that govern cell adhesion, contact inhibition, and chemotaxis. Elevating cellular polyP increases filopodial stability and enhances cell adhesion, whereas reducing polyP accelerates filopodial disassembly and promotes cell migration. Mechanistically, we find that polyP acts as a structural filopodial scaffold, recruiting and organizing IRSp53, a membrane curvature inducing protein. We show that metastatic fibroblasts and breast cancer organoids carry markedly reduced and intracellularly reorganized polyP levels relative to their non transformed counterparts. Restoring endogenous polyP via lipid nanoparticle delivery suppresses their invasive phenotypes and reverses prometastatic gene expression signatures, implicating polyP as a primordial tumor suppressor.

cell biology↗
bioRxiv2026

Mitochondrial transfer mediates metabolic communication between beta cells and islet macrophages

Pancreatic islet macrophages support islet homeostasis and adapt their metabolic program in response to environmental cues, including beta cell released factors. Intercellular mitochondrial transfer is a biological process that modulates cellular responses. To test whether beta cells, which are strongly secretory, transfer mitochondria to islet macrophages, we generated mice with beta cell-specific expression of mitochondrial GFP (PhAMfloxIns1Cre). We demonstrate that beta cells transfer mitochondria to islet macrophages in vivo and in vitro. Diabetogenic stressors did not alter the frequency of mitochondrial transfer and macrophages containing beta cell-derived GFP exhibit increased protein synthesis rates. RNA-seq identified upregulation of activity-regulated cytoskeleton associated protein (Arc) in macrophages receiving beta cell-derived mitochondria, while disruption of actin cytoskeleton dynamics prevented mitochondrial transfer. Together, these findings identify mitochondrial transfer as a previously unrecognized mechanism of beta cell-macrophage communication that may contribute to islet homeostasis and immune regulation.

cell biology↗