Biology subjects

Cavadas, C.

Publications and source records attributed to Cavadas, C..

5 recordsLinked to original sources

bioRxiv2025

An astrocytic AMPK clock drives circadian behaviour

Circadian clocks coordinate behaviour and physiology with daily cycles of light and nutrient availability, but how metabolic signals influence brain timing remains incompletely understood. Astrocytes integrate metabolic and hormonal cues and exhibit time-of-day-dependent responses, suggesting that they may convey temporal information to hypothalamic circuits. Here, we show that hypothalamic AMP-activated protein kinase (AMPK) exhibits circadian regulation independently of light and feeding cues, is modulated by nutrient availability and astrocytic Ca{superscript 2} signalling, and regulates the temporal organisation of the hypothalamic phosphoproteome. Genetic manipulation of astrocytic AMPK signalling alters PER2 abundance and phosphorylation, including at a conserved residue implicated in circadian period regulation. At the behavioural level, AMPK and PER2 in ventromedial hypothalamic astrocytes contribute to food-anticipatory activity, whereas disruption of astrocytic AMPK signalling alters SCN-dependent circadian locomotor rhythms and energy homeostasis in a sex-dependent manner. Together, these findings identify astrocytic AMPK signalling as a temporally regulated pathway that couples metabolic signals to hypothalamic circadian timing and systemic homeostasis.

neuroscience↗

bioRxiv2025

Extracellular matrix mechanical cues (dys)regulate metabolic redox homeostasis due to impaired autophagic flux

Extracellular matrix (ECM) stiffness is increasingly recognized as a critical regulator of cellular behavior, governing processes such as proliferation, differentiation, and metabolism. Neurodegenerative diseases are characterized by mitochondrial dysfunction, oxidative stress, impaired autophagy, and progressive softening of the brain tissue, yet research into how mechanical cues influence cellular metabolism in this context remains scarce. In this study, we evaluated the long-term effects of brain-compliant, soft ECM on mitochondrial bioenergetics, redox balance, and autophagic capacity in neuronal cells. Using human neuroblastoma (SH-SY5Y) and mouse hippocampal (HT22) cell lines, as well as primary mouse neurons, we observed that prolonged exposure to soft ECM resulted in mitochondrial bioenergetic dysfunction, redox imbalance, and disrupted autophagic flux. These findings were consistently validated across both human and mouse neuronal cells. Our data indicate a decreased maximal autophagic capacity in cells exposed to long-term soft ECM, potentially due to an imbalance in autophagosome formation and degradation, as demonstrated by decreased LC3 II levels following chloroquine-induced autophagic flux inhibition. This impairment in autophagy was coupled with increased cellular oxidative stress, further indicating metabolic alterations. These findings emphasize the critical role of ECM stiffness in regulating neuronal cell metabolism and suggest that prolonged exposure to soft ECM may mimic key aspects of neurodegenerative disease pathology, thereby enhancing the physiological relevance of in vitro models. This study underscores the necessity for further research into ECM mechanics as a contributing factor in neurodegenerative disease progression and as a potential target for therapeutic strategies.

cell biology↗

bioRxiv2025

Circadian Rhythms are Disrupted in Patients and Preclinical Models of Machado-Joseph Disease

Machado-Joseph disease (MJD) is caused by an abnormal CAG repeat expansion in the ATXN3 gene, leading to the expression of a mutant ataxin-3 (mutATXN3) protein. MJD patients exhibit a wide range of clinical symptoms, including motor incoordination. Emerging evidence highlights circadian rhythm disruptions as early indicators and potential risk factors for the progression of neurodegenerative conditions. Circadian rhythms are regulated by internal clocks, with the suprachiasmatic nucleus (SCN) acting as the master pacemaker to synchronize timing across the bodys behavioural and physiological functions. While sleep disturbances have been observed in MJD, the role of clock regulation in its pathophysiology remains largely unexplored in spinocerebellar ataxias. This study aimed to investigate circadian rhythms, characterize associated disruptions, and uncover the mechanisms underlying clock dysregulation in patients and preclinical models of MJD. Circadian activity in MJD patients was assessed over two weeks using actigraphy, while in a YAC-MJD transgenic mouse model, circadian rhythms were examined through: (a) wheel-running experiments; (b) telemetry-based monitoring of core body temperature; (c) immunohistochemical analysis of the neuropeptides arginine vasopressin (AVP) and vasoactive intestinal polypeptide (VIP) in the SCN and paraventricular nucleus (PVN); and (d) RT-qPCR evaluation of clock gene expression in the cerebellum. The impact of mutATXN3 on clock mechanisms was further investigated using Bmal1/Per2-luciferase reporters. MJD patients exhibited a progressive decline in robustness of behavioural rhythms, demonstrated by negative correlations between the circadian function index, rest-activity fragmentation, and sleep efficiency with MJD clinical scales. YAC-MJD mice exhibited reduced activity levels, increased behavioural fragmentation, and required three additional days to re-entrain after a jet lag protocol, compared to controls. Disrupted core body temperature rhythms were observed, including a phase advance and elevated temperature ([~]1 {degrees}C) at the onset of the active period. Furthermore, transgenic mice showed reduced levels of VIP and AVP in the SCN and PVN, and decreased clock gene expression in the cerebellum. Lastly, we found new mechanistic evidence that WT ATXN3 activates the promoters of Bmal1 and Per2, whereas mutATXN3 loses the capacity to drive Per2 upon polyglutamine expansion. Overall, our findings indicate that central clock dysfunction in MJD is associated with impaired clock gene expression and disruptions in activity and temperature rhythms. This study provides the first robust evidence of circadian rhythm dysregulation and underlying mechanisms in MJD, paving the way for the identification of new biomarkers and the development of novel circadian-based interventions to tackle MJD and possibly other spinocerebellar ataxias. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/631212v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@25078dorg.highwire.dtl.DTLVardef@112e523org.highwire.dtl.DTLVardef@1818356org.highwire.dtl.DTLVardef@1d5a6c0_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Nuclear aging in polyglutamine-induced neurodegeneration

Machado-Joseph disease (MJD) is an autosomal dominantly-inherited neurodegenerative disorder characterized by an over-repetition of the CAG trinucleotide of the ATXN3 gene, conferring a toxic gain-of-function to the resulting ataxin-3 protein. Despite the significant advances produced over the last years, the molecular mechanisms involved in MJD are still unclear and no treatment able to modify the disease progression is available. Aging is the major risk factor for neurodegenerative disorders, being associated with the occurrence and progression of several diseases, such as Alzheimers, Huntingtons, among others. The nuclear membrane proteins - lamins - and lamin-processing related proteins, such as ZMPSTE24, have been shown to be altered, not only during normal aging, but also in neurodegenerative disorders, such as Alzheimers disease. Taking this into account, we aimed at investigating the role of aging in MJD by evaluating the presence of age-related markers in human and animal MJD models. Decreased levels of lamins B and C, together with decreased ZMPSTE24 levels were identified in the different MJD models. Accordingly, abnormalities in nuclear circularity, a hallmark of aging, were also observed in a N2a MJD cellular model, supporting an age-related phenotype. Furthermore, overexpressing progerin, the abnormal lamin A, generated in Hutchinson Guilford Progeria Syndrome patients that present premature and accelerated aging, in a relevant brain area of a lentiviral MJD mouse model, induced an aggravation of MJD-associated neuropathology. Our results suggest that aging is a key player in the context of MJD pathogenesis, unveiling new pathways for the development of future therapies for the disease.

neuroscience↗

bioRxiv2023

Ghrelin delays premature aging in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal genetic condition arising from a single nucleotide alteration in the LMNA gene, which leads to the production of a defective lamin A protein known as progerin. The buildup of progerin hastens the onset of premature and expedited aging. Patients with HGPS exhibit short stature, low body weight, lipodystrophy, metabolic dysfunction, and skin and musculoskeletal abnormalities and, in most cases, die of cardiovascular disease by their early teenage years. Currently, no effective cure or treatment for the disease highlights the importance of discovering new therapeutic strategies. Herein, we present evidence that the hormone ghrelin, besides promoting autophagy and progerin clearance, rescued several cellular hallmarks of premature aging of human HGPS fibroblasts. Using an HGPS mouse model, LmnaG609G/G609G mice, we also show that ghrelin administration rescued the short-lived mice molecular and histopathological progeroid features, prevented progressive weight loss at later stages, reverted the lipodystrophic phenotype, and extended lifespan. Thus, we disclose that modulation of ghrelin signaling may give rise to new treatment targets and translational approaches that may improve outcomes and the health quality of HGPS patients and natural aging pathologies.

physiology↗