Biology subjects

Swain, S. M.

Publications and source records attributed to Swain, S. M..

5 recordsLinked to original sources

bioRxiv2026

Impact of Trastuzumab and Pertuzumab on HER2 Localization and the Estrogen Receptor Cistrome in ER+/HER2+ Breast Cancer

Background: Although anti-HER2 monoclonal antibody therapy with trastuzumab and pertuzumab is highly effective for HER2-positive breast cancer, co-expression of estrogen receptor (ER) significantly reduces pathologic complete response rates. Objective: We investigated how HER2-targeted inhibition affects HER2 cellular localization and ER genomic binding in ER-positive, HER2-positive breast cancer. Methods: We evaluated HER2 localization in a tissue microarray of treatment-naive patients. Using cellular fractionation, immunofluorescence, chromatin immunoprecipitation, and genome-wide profiling (CUT&RUN), we evaluated HER2 localization and ER genomic binding following acute anti-HER2 treatment and in models of treatment resistance. The treatment-induced ER-bound gene signature was assessed for associations with pathologic complete response and survival in breast cancer clinical cohorts. Results: In treatment-naive primary breast tumors, nuclear HER2 inversely correlated with ER levels. In cell models, treatment with trastuzumab and pertuzumab induced nuclear and chromatin accumulation of HER2. Concurrently, acute anti-HER2 treatment displaced ER from canonical estrogen response elements at classical target genes, yet genome-wide profiling revealed redistribution of ER binding toward non-canonical zinc finger motifs adjacent to pro-survival Wnt and RAGE pathway genes (FZD8, RELA). Expression of a drug-induced ER-bound gene signature was significantly higher in tumors of individuals who did not achieve pathologic complete response following neoadjuvant anti-HER2 therapy and significantly correlated with reduced distant metastasis-free survival in clinical cohorts. Conclusions: Anti-HER2 targeted therapy causes dynamic cistromic reprogramming of ER from classical estrogen pathways toward alternative pro-survival networks. These findings implicate ER redistribution as a possible mediator of resistance and highlight novel therapeutic targets in ER-positive, HER2-positive breast cancer.

cancer biology↗

bioRxiv2023

Piezo1-induced durotaxis of pancreatic stellate cells depends on TRPC1 and TRPV4 channels

Pancreatic stellate cells (PSCs) are primarily responsible for producing the stiff tumor tissue in pancreatic ductal adenocarcinoma (PDAC). Thereby, PSCs generate a stiffness gradient between the healthy pancreas and the tumor. This gradient induces durotaxis, a form of directional cell migration driven by differential stiffness. The molecular sensors behind durotaxis are still unclear. To investigate the role of mechanosensitive ion channels in PSC durotaxis, we established a two-dimensional stiffness gradient mimicking PDAC. Using pharmacological and genetic methods, we investigated the role of the ion channels Piezo1, TRPC1, and TRPV4 in PSC durotaxis. We found that PSC migration towards a stiffer substrate is diminished by altering Piezo1 activity. Moreover, disrupting TRPC1 along with TRPV4 abolishes PSC durotaxis even when Piezo1 is functional. Hence, PSC durotaxis is optimal with an intermediary level of mechanosensitive channel activity, which we simulated using a numerically discretized mathematical model. Our findings suggest that mechanosensitive ion channels, particularly Piezo1, detect the mechanical microenvironment to guide PSC migration. SummaryCells move towards regions with higher stiffness in a process called durotaxis. This study shows that ion channels Piezo1, TRPV4, and TRPC1 are crucial sensors in pancreatic stellate cells. They act together to orchestrate durotaxis of pancreatic stellate cells which may be relevant in pancreatic cancer.

physiology↗

bioRxiv2023

Gut mucosal cells transfer α-synuclein to the vagus nerve

Epidemiological and histopathological findings have raised the possibility that misfolded -synuclein protein might spread from the gut to the brain and increase the risk of Parkinsons disease (PD). While past experimental studies in mouse models have relied on gut injections of exogenous recombinant -synuclein fibrils to study gut to brain -synuclein transfer, the possible origins of misfolded -synuclein within the gut have remained elusive. We recently demonstrated that sensory cells of the gut mucosa express -synuclein. In this study, we employed mouse intestinal organoids expressing human -synuclein to observe the transfer of -synuclein protein from gut epithelial cells in organoids co-cultured with vagal nodose neurons that are otherwise devoid of -synuclein expression. In intact mice that express pathological human -synuclein, but no mouse -synuclein, -synuclein fibril templating activity emerges in -synuclein seeded fibril aggregation assays in tissues from the gut, vagus nerve, and dorsal motor nucleus. In newly engineered transgenic mice that restrict pathological human -synuclein expression to intestinal epithelial cells, -synuclein fibril-templating activity transfers to the vagus nerve and to the dorsal motor nucleus. Subdiaphragmatic vagotomy prior to the induction of -synuclein expression in the gut epithelial cells effectively protects the hindbrain from the emergence of -synuclein fibril templating activity. Overall, these findings highlight a novel potential non-neuronal source of fibrillar -synuclein protein that might arise in gut mucosal cells.

neuroscience↗

bioRxiv2022

Overexpression of the WAPO-A1 gene increases the number of spikelets per spike in bread wheat

Two homoeologous QTLs for number of spikelets per spike (SPS) were mapped on chromosomes 7AL and 7BL using two wheat MAGIC populations. Sets of lines contrasting for the QTL on 7AL were developed which allowed for the validation and fine mapping of the 7AL QTL and for the identification of a previously described candidate gene, WHEAT ORTHOLOG OF APO1 (WAPO1). Using transgenic overexpression in both a low and a high SPS line, we provide a functional validation for the role of this gene in determining SPS also in hexaploid wheat. We show that the expression levels of this gene positively correlate with SPS in multiple MAGIC founder lines under field conditions as well as in transgenic lines grown in the greenhouse. This work highlights the potential use of WAPO1 in hexaploid wheat for further yield increases. The impact of WAPO1 and SPS on yield depends on other genetic and environmental factors, hence, will require a finely balanced expression level to avoid the development of detrimental pleiotropic phenotypes.

plant biology↗

bioRxiv2020

Shear stress-induced pathological changes in endothelial cells occur through Piezo1 activation of TRPV4

Although the ion channels Piezo1 and TRPV4 have been implicated in high venous pressure- and fluid shear stress-induced vascular hyperpermeability, they have been described as working independently. Moreover, the mechanism by which Piezo1 and TRPV4 channels in endothelial cells execute the same function is poorly understood. Here we demonstrate that Piezo1 regulates TRPV4 channel activation in endothelial cells and that Piezo1-mediated TRPV4 channel opening is a function of the strength and duration of fluid shear stress. Application of the Piezo1 antagonist, GsMTx4, completely blocked the elevation in intracellular calcium ([Ca2+]i) induced by both fluid shear stress and the Piezo1 agonist, Yoda1. High and prolonged shear stress caused sustained [Ca2+]i elevation which required TRPV4 opening and was responsible for fluid shear stress- and Piezo1-mediated disruption of adherens junctions and actin remodeling. We found that Piezo1’s effects were mediated by phospholipase A2 activation. Blockade of TRPV4 channels with the selective TRPV4 blocker, HC067047, prevented the loss of endothelial cell integrity and actin disruption induced by Yoda1 or shear stress and prevented Piezo1-induced monocyte adhesion to endothelial cell monolayers. These findings demonstrate that Piezo1 activation by fluid shear stress initiates a calcium signal that causes TRPV4 opening which in turn is responsible for the sustained phase calcium elevation that triggers pathological events in endothelial cells.The abbreviations used areHUVEChuman umbilical vein endothelial cellTRPV4transient receptor potential vanilloid subfamily 4PLA2phospholipase A2AJsadherens junctions5′,6′-EET5′,6′-epoxyeicosatrienoic acidHC067HC067047GSK101GSK1016790APVPpulmonary venous pressureView Full Text

cell biology↗