Biology subjects

Coughlin, M.

Publications and source records attributed to Coughlin, M..

5 recordsLinked to original sources

bioRxiv2026

Onsite fixation preserves phosphoprotein profile in human whole blood

Phospho-flow cytometry is increasingly used as a pharmacodynamic readout of kinase-pathway activity, including in JAK inhibitor trials. Phosphoprotein states are intrinsically labile ex vivo and are further altered by conventional workflows, which typically involve PBMC isolation, cryopreservation, and transit times of hours to days before measurement. Here, we fix whole blood at collection and quantify six phosphoproteins by mass cytometry, benchmarked against matched cryopreserved PBMCs. Unlike PBMCs, whole blood retained neutrophils, ~75-80% of which were pSTAT3-positive at baseline. Basal pSTAT3 was also markedly higher in whole blood monocytes (~41% positive vs. ~9% in PBMCs), whereas T, B, and NK cells differed by less than 1 percentage point. Stimulation produced subset-specific phosphorylation patterns that were retained after 6 weeks of storage. Because fixation does not require centrifugation and retains neutrophils, samples can be fixed at collection sites without on-site processing laboratories and analyzed centrally in batches.

immunology↗

bioRxiv2025

Impact of sex and glial tau expression on heat shock protein induction in a Drosophila model of tauopathy

Heat shock proteins (Hsps) are central components of the cellular stress response and serve as the first line of defense against protein misfolding and aggregation. Disruption of this proteostasis network is a hallmark of neurodegenerative diseases, including tauopathies - a class of neurodegenerative diseases characterized by intracellular tau accumulation in neuronal and glial cells. Although specific Hsps are enriched in glial cells, and some have been shown to directly bind tau and influence its aggregation, the broader interplay between Hsps and tau remains poorly understood. In particular, it is unclear whether tau expression affects the heat shock response, and whether this interaction is modulated in a sex-specific fashion. Here, we used a Drosophila model of tauopathy to examine both inducible and constitutive Hsp expression in response to heat stress in the context of glial tau expression. We found that Hsp expression displays sexually dimorphic expression patterns at basal levels and in response to heat stress. Moreover, tau expression in glia disrupts the normal induction of specific heat shock proteins following heat stress. This work provides new insight into how tau interacts with the cellular stress response, and highlights sex-specific differences in Hsp regulation. Understanding these molecular connections is crucial to understanding how the presence of tau in glial cells influences the stress response, and potentially contributes to tauopathy pathogenesis.

neuroscience↗

bioRxiv2025

Remodeling of self-assembled microvascular networks under long term flow

The incorporation of a functional perfusable microvascular network (MVN) is a common requirement for most organ on-chip-models. Long-term perfusion of MVNs is often required for the maturation of organ phenotypes and disease pathologies and to model the transport of cells and drugs entering organs. In our microphysiological system, we observe that flow can recover perfusion in regressed MVNs and maintain perfusable MVNs for at least 51 days. Throughout the 51 days, however, the MVNs are continuously remodeling to align with the direction of bulk flow and only appear to attain morphological homeostasis with the use of maintenance medium without growth factors. We observed that the flow resistance of the MVNs decreases over time, and using a computational model, we show that stable vessels have higher flow rates and velocities compared to regressing vessels. Cytokine analysis suggests that static conditions generate an inflammatory state, and that continuous flow reduces inflammation over an extended period. Finally, through bulk RNA sequencing we identify that both the endothelial and fibroblast cells are actively engaged in vascular and matrix remodeling due to flow and that these effects persist for at least 2 weeks. This MPS can be applied to study hemodynamically driven processes, such as metastatic dissemination or drug distribution, or to model long-term diseases previously not captured by MPS, such as chronic inflammation or aging-associated diseases.

biophysics↗

bioRxiv2021

Glycogen-dependent demixing of frog egg cytoplasm at increased crowding

Crowding increases the tendency of macromolecules to aggregate and phase separate, and high crowding can induce glass-like states of cytoplasm. To explore the effect of crowding in a well-characterized model cytoplasm we developed methods to selectively concentrate components larger than 25 kDa from Xenopus egg extracts. When crowding was increased 1.4x, the egg cytoplasm demixed into two liquid phases of approximately equal volume. One of the phases was highly enriched in glycogen while the other had a higher protein concentration. Glycogen hydrolysis blocked or reversed demixing. Quantitative proteomics showed that the glycogen phase was enriched in proteins that bind glycogen, participate in carbohydrate metabolism, or are in complexes with especially high native molecular weight. The glycogen phase was depleted of ribosomes, ER and mitochondria. These results inform on the physical nature of a glycogen-rich cytoplasm and suggest a role of demixing in the localization of glycogen particles in tissue cells.

cell biology↗

bioRxiv2020

Glycocalyx-Mediated Vascular Dissemination of Circulating Tumor Cells

The glycocalyx on tumor cells has been recently identified as an important driver for cancer progression, possibly providing critical opportunities for treatment. Metastasis, in particular, is often the limiting step in the survival to cancer, yet our understanding of how tumor cells escape the vascular system to initiate metastatic sites remains limited. Using an in vitro model of the human microvasculature, we assess here the importance of the tumor and vascular glycocalyces during tumor cell extravasation. Through selective manipulation of individual components of the glycocalyx, we reveal a novel mechanism whereby tumor cells prepare an adhesive vascular niche by depositing components of the glycocalyx along the endothelium. Accumulated hyaluronic acid shed by tumor cells subsequently mediates adhesion to the endothelium via the glycoprotein CD44. Trans-endothelial migration and invasion into the stroma occurs through binding of the isoform CD44v to components of the sub-endothelial extra-cellular matrix. Targeting of the hyaluronic acid-CD44 glycocalyx complex results in significant reduction in the extravasation of tumor cells. These studies provide evidence of tumor cells repurposing the glycocalyx to promote adhesive interactions leading to cancer progression. Such glycocalyx-mediated mechanisms may be therapeutically targeted to hinder metastasis and improve patient survival.

cancer biology↗