Biology subjects

Caldarelli, A.

Publications and source records attributed to Caldarelli, A..

4 recordsLinked to original sources

bioRxiv2026

Isogenic cortical organoids enable precision targeting of APP variant-specific pathways in Alzheimer's disease

Alzheimers disease (AD) lacks disease-modifying therapies, in part due to the limitations of existing disease models, which have struggled to capture the early pathogenic events leading to neuronal degeneration. Unfortunately, recent therapies targeting hallmarks of AD have proven inefficient in humans, and it is thus necessary to identify alternative targets. Here, by generating an isogenic panel of hiPSC-derived cortical organoids carrying familial AD-associated APP variants or the protective A673T variant, we identified distinct, actionable pathogenic pathways specific to each variant. Proteomic analyses revealed variant-specific molecular disruptions: A673V organoids show impairments in proteostasis and cholesterol metabolism, whereas KM670/671NL organoids exhibit mitochondrial bioenergetic defects. These signatures overlapped with dysregulated proteins in post-mortem AD brains, demonstrating the reliability of our in vitro model. Importantly, targeted interventions restored neuronal survival in a variant-specific manner: overexpression of the master regulator of lysosomal biogenesis, TFEB, rescued A673V neurons, while ferroptosis inhibition selectively protected KM670/671NL neurons. Overall, our results indicate that differential treatments can be tailored based on distinct genetic backgrounds, supporting the development of precision medicine approaches in AD.

neuroscience↗

bioRxiv2025

Altered lysosomal biology impairs motor neuron survival via TFEB dysregulation in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a devastating motor neuron disease, caused by recessive mutations or deletions of the SMN1 gene, representing the leading genetic cause of infant mortality. Available therapies, aimed at increasing SMN protein levels, can only partially halt motor neuron (MN) degeneration in a select number of patients, reinforcing the need for combinatorial treatments to improve clinical outcomes. We previously showed that mTORC1 overactivation and impaired autophagosome clearance in SMA MNs lead to the accumulation of protein aggregates, contributing to MN degeneration. However, the mechanistic link between SMN protein deficiency and autophagy-lysosomal dysfunction remained unknown. Here, using patient iPSC-derived MNs along with isogenic and healthy controls, we show that SMA MNs exhibit reduced lysosome numbers and impaired functionality. Furthermore, the master regulator of lysosomal biogenesis and autophagy, TFEB, is downregulated, and its nuclear translocation compromised upon SMN deficiency. We further propose the upregulation of the mTORC1 positive modulator TPT1 as contributor to TFEB dysregulation. Notably, TFEB overexpression ameliorates protein aggregate accumulation in SMA MNs and enhances MN survival both in vitro and in a zebrafish SMA model. Our findings identify lysosomal dysfunction as a key player in SMA pathology and highlight TFEB activation as a potential therapeutic strategy for SMA treatment. One Sentence SummaryTFEB activation restores lysosomal function and improves motor neuron survival in SMA, highlighting its potential as a therapeutic target.

neuroscience↗

bioRxiv2024

Synchronous 3D patterning of diverse CNS progenitors generates motor neurons of broad axial identity

In vitro human organoid models have become transformative tools for studying organogenesis, enabling the generation of spinal cord organoids (SCOs) that mimic aspects of spinal cord biology. However, current models do not produce spinal motor neurons (spMNs) with a wide range of axial identities along spinal cord segments within a single structure, limiting their utility in understanding human neural axial specification and the selective vulnerability of spMN subpopulations in motor neuron diseases. Here, we present a novel approach to enhance spMN axial heterogeneity in an advanced SCO model derived from neural stem cells (NSCs) and retinoic acid (RA)-primed neuromesodermal progenitors (NMPs). RA priming guided NMP differentiation into caudal neural progenitors, generating SCOs enriched in spMNs with posterior axial identities. To further diversify spMN populations, we optimized differentiation by synchronously patterning NSCs with RA-primed NMPs. Incorporating an endothelial-like network and skeletal muscle cells enhanced the organoids physiological complexity and neural maturation and organoid cell viability. This comprehensive approach, termed CASCO, provides a robust platform to study human spMN specification and model neurodegenerative diseases.

neuroscience↗

bioRxiv2022

Telomerase-independent maintenance of telomere length in a vertebrate

Telomere shortening places a key limitation on cell proliferation1. In all vertebrates explored to date, this limitation is overcome by telomerase-dependent telomere extension. Failure to maintain telomere length results in premature ageing and functional impairments in highly replicative cell populations as telomeres erode2. Alternative lengthening of telomeres (ALT), a telomerase-independent mechanism, compensates for telomere loss in a subset of human cancer cell lines 2. Here, we demonstrate that the highly regenerative newt Pleurodeles waltl lacks telomerase activity, contains telomeres distinct from all known vertebrates in both sequence and structure, and deploys ALT for physiological telomere maintenance. This constitutes the first report of telomerase-independent resolution of the end-replication problem at the whole-organism level within Chordata. One-Sentence SummaryP. waltl telomere biology is distinct amongst vertebrates and uses ALT at the whole-organism level.

molecular biology↗