Biology subjects

Belaya, I.

Publications and source records attributed to Belaya, I..

4 recordsLinked to original sources

bioRxiv2024

Signaling downstream of tumor-stroma interaction regulates mucinous colorectal adenocarcinoma apicobasal polarity

Mucinous colorectal carcinoma (MUC CRC) dissemination into the tumor stroma and metastasis to multiple organs, including the peritoneum, is associated with poor prognosis. Disseminating MUC CRCs exhibit either a conventional apical-in or an inverted apical-out polarity phenotype that influence patient outcome. Identifying the mechanisms controlling MUC CRC polarity is critical to understand disease progression. Here, we analyze patient-derived MUC CRC xenografts, with apical-in or apical-out polarity, ex vivo or within collagen gels to mimic the peritumoral stroma. Single-cell analyses reveal 2{beta}1-integrin as a key collagen-binding receptor in these models. Collagen-2{beta}1-integrin interaction activates Src and ERK/MAPK signaling and upregulates the expression of SorLA, an endosomal sorting receptor. SorLA supports apical-in polarity and carcinoma-stroma interactions by promoting integrin recycling to the plasma membrane and HER2/HER3 expression through a positive feedback mechanism. Accordingly, we observe positive correlation between HER2, HER3 and SorLA in patient samples with the highest HER2 expression in apical-in-presenting tissues. Treatment of tumor spheres with clinically relevant HER2/HER3-targeting antibodies reverts sphere polarity and impedes collagen remodeling and adhesion to mouse peritoneum. This SorLA--integrin--HER2/HER3 signaling axis may represent a basis for MUC CRC-patient stratification and shed light on other carcinomas with similar apical-out phenotypes.

cancer biology↗

bioRxiv2022

Microglial amyloid beta clearance is driven by PIEZO1 channels

BackgroundMicroglia are the endogenous immune cells of the brain and act as sensors of pathology to maintain brain homeostasis and eliminate potential threats. In Alzheimers disease (AD), toxic amyloid beta (A{beta}) accumulates in the brain and forms stiff plaques. In late-onset AD accounting for 95% of all cases, this is thought to be due to reduced clearance of A{beta}. Human genome-wide association studies and animal models suggest that reduced clearance results from aberrant function of microglia. While the impact of neurochemical pathways on microglia have been broadly studied, mechanical receptors regulating microglial functions remain largely unexplored. MethodsHere we showed that a mechanotransduction ion channel, PIEZO1, is expressed and functional in human and mouse microglia. We used a small molecule agonist, Yoda1, to study how activation of PIEZO1 affects AD-related functions in human induced pluripotent stem cell (iPSC) -derived microglia-like cells (iMGL) under controlled laboratory experiments. Cell survival, metabolism, phagocytosis and lysosomal activity were assessed using real-time functional assays. To evaluate the effect of activation of PIEZO1 in vivo, 5-month-old 5xFAD male mice were infused daily with Yoda1 for two weeks through intracranial cannulas. Microglial Iba1 expression and A{beta} pathology were quantified with immunohistochemistry and confocal microscopy. Published human and mouse AD datasets were used for in-depth analysis of PIEZO1 gene expression and related pathways in microglial subpopulations. ResultsWe show that PIEZO1 orchestrates A{beta} clearance by enhancing microglial survival, phagocytosis, and lysosomal activity. A{beta} inhibited PIEZO1-mediated calcium transients, whereas activation of PIEZO1 with a selective agonist, Yoda1, improved microglial phagocytosis resulting in A{beta} clearance both in human and mouse models of AD. Moreover, PIEZO1 expression was associated with a unique microglial transcriptional phenotype in AD as indicated by assessment of cellular metabolism, and human and mouse single cell datasets. ConclusionThese results indicate that the compromised function of microglia in AD could be improved by controlled activation of PIEZO1 channels resulting in alleviated A{beta} burden. Pharmacological regulation of these mechanoreceptors in microglia could represent a novel therapeutic paradigm for AD. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=176 HEIGHT=200 SRC="FIGDIR/small/484831v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@832eadorg.highwire.dtl.DTLVardef@6d8719org.highwire.dtl.DTLVardef@c09740org.highwire.dtl.DTLVardef@9fa85_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2021

Alzheimer's disease alters astrocytic functions related to neuronal support andtranscellular internalization of mitochondria

Under physiological conditions in vivo astrocytes internalize and degrade neuronal mitochondria in a process called transmitophagy. Mitophagy is widely reported to be impaired in neurodegeneration but it is unknown whether and how transmitophagy is altered in Alzheimers disease (AD). Here we report that the internalization and degradation of neuronal mitochondria are significantly increased in astrocytes isolated from aged AD mouse brains. We also demonstrate for the first time a similar phenomenon between human neurons and AD astrocytes, and in murine hippocampi in vivo. The results suggest the involvement of S100a4 in impaired mitochondrial transfer between neurons and aged AD astrocytes. Significant increases in the mitophagy regulator Ambra1 were observed in the aged AD astrocytes. These findings demonstrate altered neuron-supporting functions of aged AD astrocytes and provide a starting point for studying the molecular mechanisms of transmitophagy in AD.

neuroscience↗

bioRxiv2021

Subacute Inhalation of Ultrafine Particulate Matter Triggers Inflammation Without Altering Amyloid Beta Load in 5xFAD mice.

Epidemiological studies reveal that air pollution exposure may exacerbate neurodegeneration. Ultrafine particles (UFPs) are pollutants that remain unregulated in ambient air by environmental agencies. Due to their small size (<100nm), UFPs have the most potential to cross the bodily barriers and thus impact the brain. However, little information exists about how UFPs affect brain function. Alzheimers disease (AD) is the most common form of dementia, which has been linked to air pollutant exposure, yet limited information is available on the mechanistic connection between them. This study aims to decipher the effects of UFPs in the brain and periphery using the 5xFAD mouse model of AD. In our study design, AD mice and their wildtype littermates were subjected to 2-weeks inhalation exposure of UFPs in a whole-body chamber. That subacute exposure did not affect the blood-brain barrier integrity or amyloid-beta accumulation. However, when multiple cytokines were analyzed, we found increased levels of proinflammatory cytokines in the brain and periphery, with a predominant alteration of interferon-gamma in response to UFP exposure in both genotypes. Following exposure, mitochondrial superoxide dismutase was significantly upregulated only in the 5xFAD hippocampi, depicting oxidative stress induction in the exposed AD mouse group. These data demonstrate that short-term exposure to inhaled UFPs induces inflammation without affecting amyloid-beta load. This study provides a better understanding of adverse effects caused by short-term UFP exposure in the brain and periphery, also in the context of AD. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/459017v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@479511org.highwire.dtl.DTLVardef@18bc59aorg.highwire.dtl.DTLVardef@15a0240org.highwire.dtl.DTLVardef@49f911_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗