Biology subjects

Alatza, A.

Publications and source records attributed to Alatza, A..

4 recordsLinked to original sources

bioRxiv2026

Metformin promotes broad neuroprotection and proteostatic resilience via rngo/DDI2 stabilisation

Alzheimers disease (AD) is one of the most common age-related causes of death, with limited effective disease-modifying treatments. Although metformin shows promise as a disease-modifying agent for AD, its molecular mechanism--specifically how it confers neuroprotection despite potentially increasing amyloid-beta (A{beta}) load--remains obscure. Here, we demonstrate that metformin functions as a pharmacological activator of the ubiquitin-binding protease rngo/DDI2. Through a genetic screen in Drosophila, we identified rngo/DDI2 as a potent suppressor of A{beta} toxicity. We provide in silico and genetic evidence that metformin interacts with the conserved D257 residue of the rngo/DDI2 RVP domain, inducing homodimerisation and subsequent protein stabilisation. This activation boosts proteasome activity in the presence of A{beta} preferentially clearing highly abundant proteins to preserve proteostasis. Crucially, this intervention is broadly effective; rngo/DDI2 upregulation robustly suppresses toxicity in models of TDP-43 and C9orf72-repeat expansion pathology, indicating a generalised mechanism of neuroprotection. Supported by human iPSC data and evidence of DDI2 depletion in AD patient brains, our results identify rngo/DDI2 as a conserved regulator of neuronal resilience. We propose that directly targeting DDI2 stabilisation represents a novel, broadly applicable therapeutic strategy to counteract proteotoxic stress across a broad spectrum of neurodegenerative diseases.

neuroscience↗

bioRxiv2024

Age and amyloidβ-dependent initiation of neurofibrillary tau tangles: an improved mouse model of Alzheimers disease without mutations in MAPT.

The lack of models in which ageing and amyloid-{beta} (A{beta}) initiate neurofibrillary tau tangles, independent of MAPT mutations, limits mechanistic insights into Alzheimers disease. Here, we characterise NLFTaum/h, a novel mouse model that recapitulates the gradual transition from A{beta} accumulation to tau pathology by 24 months. We show that combined effects of ageing, A{beta}, and human tau expression promote tau pathology. However, either A{beta} plaques or human tau alone can initiate tau pathology, but only in even older mice. This may be exacerbated by increased neuronal vulnerability across all genotypes with age. Moreover, multi-omic analyses reveal that human tau can induce early alterations in mitochondrial and synaptic pathways, priming this latent vulnerability preceding tau pathology. Together, this suggests that ageing and other interacting triggers accelerate the onset of tau pathology. This opens possibilities for translatable testing of improved therapies for Alzheimers disease, breaking the link between A{beta} and tau pathologies.

neuroscience↗

bioRxiv2024

Mutations in PSEN1 predispose inflammation in an astrocyte model of familial Alzheimer's disease through disrupted regulated intramembrane proteolysis

Mutations in PSEN1 cause familial Alzheimers disease with almost complete penetrance. Age at onset is highly variable between different PSEN1 mutations and even within families with the same mutation. Current research into late onset Alzheimers disease implicates inflammation in both disease onset and progression. PSEN1 is the catalytic subunit of {gamma}-secretase, responsible for regulated intramembrane proteolysis of numerous substrates that include cytokine receptors. For this reason, we tested the hypothesis that mutations in PSEN1 impact inflammatory responses in astrocytes, thereby contributing to disease progression. Here, using iPSC-astrocytes, we show that PSEN1 is upregulated in response to inflammatory stimuli, and this upregulation is disrupted by pathological PSEN1 mutations. Using transcriptomic analyses, we demonstrate that PSEN1 mutant astrocytes have an augmented inflammatory profile in their basal state, concomitant with an upregulation of genes coding for regulated intramembrane proteolytic and robust activation of JAK-STAT signalling. Using JAK-STAT2 as an example signalling pathway, we show altered phosphorylation cascades in PSEN1 mutant astrocytes, reinforcing the notion of altered cytokine signalling cascades. Finally, we use small molecule modulators of {gamma}-secretase to confirm a role for PSEN1/{gamma}-secretase in regulating the astrocytic response to inflammatory stimuli. Together, these data suggest that mutations in PSEN1 enhance cytokine signalling via impaired regulated intramembrane proteolysis, thereby predisposing astrocytic inflammatory profiles. These findings support a two-hit contribution of PSEN1 mutations to fAD pathogenesis, not only impacting APP and A{beta} processing but also altering the cellular response to inflammation.

neuroscience↗

bioRxiv2021

Macrophage migration inhibitory factor is a valid drug target at the intersection of herpes simplex virus 1 replication and Alzheimer's disease-relevant cellular pathology

The viral life cycle usurps host cellular factors, redirecting them from physiological functions to viral needs thereby revealing their "moonlighting" functions, disturbing cellular proteostasis, and increasing risk of specific, virus-associated protein misfolding diseases (PMD). Identifying such virus-repurposed host proteins therefore allow study of fundamental cellular events leading to associated "sporadic" PMD. Here, we identified a small molecule with unprecedented activity against neurotropic herpes simplex virus 1 (HSV-1) modulating an allosteric site of Macrophage Migration Inhibitory Factor (MIF). The compound efficiently reduced HSV-1-mediated tau phosphorylation or aggregation in vitro and in vivo, even without HSV-1 infection. The lead compound specifically interacted with an oxidized conformer of MIF (oxMIF) from either recombinant MIF or post-mortem brain homogenates of patients with Alzheimers disease (AD). OxMIF thus participates in a host-viral interface connecting HSV-1 infection, and possibly other external stressors, with tau cellular pathology characteristic for PMD, including Alzheimes disease.

microbiology↗