Biology subjects

Capetillo-Zarate, E.

Publications and source records attributed to Capetillo-Zarate, E..

6 recordsLinked to original sources

bioRxiv2026

Intravital pH Imaging using the sensor ApHID Reveals Incomplete Lysosomal Acidification in Resident Meningeal Phagocytes.

Tracking lysosomes and quantifying their pH in the living, intact brain has been challenging owing to the lack of suitable in vivo tools. Here we report the use of dextran polymers labeled with the pH sensor ApHID to visualize and quantify lysosomal pH in mouse brain resident phagocytes. ApHID-dextrans delivered systemically are rapidly endocytosed by phagocytes in the meninges -mainly dural and subdural macrophages- and accumulate in lysosomal compartments. Intravital pH imaging revealed a striking heterogeneity in lysosomal acidification, with only ~5% of meningeal phagocytes reaching pH values below 5.0, in marked contrast with measurements in macrophage cell cultures. Photothrombotic ischemic lesions induced progressive lysosomal acidification in local phagocytes, while acute chloroquine treatment led to rapid alkalinization. Our methodology enables direct, quantitative pH measurements without genetic manipulations, and unveils a previously unappreciated heterogeneity in lysosomal acidification among brain-resident myeloid cells.

neuroscience↗

bioRxiv2026

An Integrated Neuroimmune Assembloid Model to Advance Neurodegenerative Disease Studies

Brain organoids are three-dimensional cultures derived from human pluripotent or embryonic stem cells that recapitulate key genetic, biochemical, and molecular features of the human brain. They provide a powerful platform for studying human brain development and modeling genetic neurological disorders. However, their application to age-dependent neurodegenerative diseases remains limited, largely due to the absence of standardized methods for incorporating functional microglia, critical regulators of neuroinflammation and disease progression. Here, we describe a strategy for generating neuroimmune assembloids, brain organoids containing functional glial cells capable of mounting inflammatory responses. By introducing hematopoietic progenitor cells into developing brain organoids, we enable their in situ maturation into microglia-like cells that persist in culture for up to one month. These cells exhibit hallmark microglial behaviors, including morphological remodeling, migration, phagocytosis and transcriptional changes in response to inflammatory stimuli. Together, these immunocompetent-like brain organoids provide a promising and versatile platform for investigating neuroimmune interactions and neuroinflammatory mechanisms underlying age-related neurodegenerative diseases.

neuroscience↗

bioRxiv2025

PKC-dependent MYRF dysregulation links Aβ pathology to oligodendrocyte, myelin and cognitive alterations in Alzheimer's disease

Alzheimers disease (AD) is characterized not only by neuronal loss and synaptic dysfunction but also by emerging evidence of oligodendrocyte and myelin pathology. Amyloid-{beta} (A{beta}), a hallmark of AD, disrupts oligodendrocyte homeostasis through mechanisms that remain poorly understood. Here, we investigated the role of the myelin regulatory factor (MYRF), a transcription factor essential for oligodendrocyte maturation, in AD-related glial dysfunction. Using the 3xTg-AD mouse model, we observed aberrantly induced maturation dynamics and reduced oligodendrocyte lineage cell density at 12 months in the dentate gyrus, accompanied by increased MYRF expression. Interestingly, sustained MYRF overexpression was found to be toxic for oligodendrocytes in vitro. Moreover, in vitro and in vivo experiments further demonstrated that A{beta} exposure elevates MYRF protein levels and enhances its transcriptional activity, pointing to post-translational regulation. Mechanistically, A{beta} impaired GSK3-dependent phosphorylation and Fbxw7-mediated ubiquitination of MYRF, prolonging N-MYRF stability, an effect prevented by PKC inhibition in vitro. Intracerebroventricular infusion of PKC inhibitor Go6983 normalized MYRF levels, restored oligodendrocyte populations and myelin integrity, and improved hippocampal-dependent spatial learning in 3xTg-AD mice, with locomotor activity and anxiety-like behavior remaining unaffected. Together, these findings identify MYRF dysregulation as a mechanistic link between A{beta}/PKC signaling and oligodendrocyte pathology, and highlight PKC inhibition as a potential strategy to restore oligodendroglial function and cognition in AD.

neuroscience↗

bioRxiv2023

The nonlinear meccano of hyperactivity in Alzheimer

The pathophysiological process of Alzheimers disease (AD) is believed to begin many years before the formal diagnosis of AD dementia. This protracted preclinical phase offers a crucial window for potential therapeutic interventions, yet its comprehensive characterization remains elusive. Accumulating evidence suggests that amyloid-{beta} (A{beta}) may mediate neuronal hyperactivity in circuit dysfunction in the early stages of AD. At the same time, neural activity can also facilitate A{beta} accumulation through intricate feed-forward interactions, complicating elucidating the conditions governing A{beta}-dependent hyperactivity and its diagnostic utility. In this study, we use biophysical modeling to shed light on such conditions. Our analysis reveals that the inherently nonlinear nature of the underlying molecular interactions can give rise to various modes of hyperactivity emergence. This diversity in the mechanisms of hyperactivity may ultimately account for a spectrum of AD manifestations.

neuroscience↗

bioRxiv2021

A neuron, microglia, and astrocyte triple coculture model to study Alzheimer disease

Glial cells are essential to understand Alzheimers disease (AD) progression, given their role in neuroinflammation and neurodegeneration. There is a need for reliable and easy to manipulate models that allow studying the mechanisms behind neuron and glia communication. Currently available models such as cocultures require complex methodologies and/or might not be affordable for all laboratories. With this in mind, we aimed to establish a straightforward in vitro setting with neurons and glial cells to study AD. We generated a triple co-culture with neurons, microglia and astrocytes. Immunofluorescence, western blot and ELISA techniques were used to characterize the effects of oligomeric A{beta} (oA{beta}) in this model. We found that, in the triple co-culture, microglia increased the expression of anti-inflammatory markers Arginase I and TGF-{beta}1, and reduced pro-inflammatory iNOS and IL-1{beta}, compared with microglia alone. Astrocytes reduced expression of pro-inflammatory A1 markers AMIGO2 and C3, and displayed a ramified morphology resembling physiological conditions. Lastly, neurons increased post-synaptic markers, and developed more and longer branches than in individual primary cultures. Addition of oA{beta} in the triple coculture reduced synaptic markers and increased microglial activation, which are hallmarks of AD. Consequently, we developed a reliable model, where cells better resemble physiological conditions: microglia are less inflammatory, astrocytes are less reactive and neurons display a more mature morphology than in individual primary cultures. Moreover, we were able to recapitulate A{beta}-induced synaptic loss and inflammation. This model emerges as a powerful tool to study neurodegeneration and inflammation in the context of AD and other neurodegenerative diseases. Table of content image O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY Main pointsO_LIIn our model, microglia and astrocytes are less reactive, and neurons have a more mature morphology than in primary cultures. C_LIO_LIoA{beta} reduced synaptic markers and increased microglial activation. C_LIO_LIThis triple co-culture is a reliable tool to study neurodegeneration and gliosis in vitro. C_LI

neuroscience↗

bioRxiv2021

Microglial phagocytosis dysfunction during stroke is prevented by rapamycin

Microglial phagocytosis is rapidly emerging as a therapeutic target in neurodegenerative and neurological disorders. An efficient removal of cellular debris is necessary to prevent buildup damage of neighbor neurons and the development of an inflammatory response. As the brain professional phagocytes, microglia are equipped with an array of mechanisms that enable them to recognize and degrade several types of cargo, including neurons undergoing apoptotic cell death. While microglia are very competent phagocytes of apoptotic cells under physiological conditions, here we report their dysfunction in mouse and monkey (Macaca fascicularis and Callithrix jacchus) models of stroke by transient occlusion of the medial cerebral artery (tMCAo). The impairment of both engulfment and degradation was related to energy depletion triggered by oxygen and nutrients deprivation (OND), which led to reduced process motility, lysosomal depletion, and the induction of a protective autophagy response in microglia. Basal autophagy, which is in charge of removing and recycling intracellular elements, was critical to maintain microglial physiology, including survival and phagocytosis, as we determined both in vivo and in vitro using knock-out models of autophagy genes and the autophagy inhibitor MRT68921. Notably, the autophagy inducer rapamycin partially prevented the phagocytosis impairment induced by tMCAo in vivo but not by OND in vitro. These results suggest a more complex role of microglia in stroke than previously acknowledged, classically related to the inflammatory response. In contrast, here we demonstrate the impairment of apoptotic cell phagocytosis, a microglial function critical for brain recovery. We propose that phagocytosis is a therapeutic target yet to be explored and provide evidence that it can be modulated in vivo using rapamycin, setting the stage for future therapies for stroke patients.

neuroscience↗