Biology subjects

Mero, S.

Publications and source records attributed to Mero, S..

3 recordsLinked to original sources

bioRxiv2025

HPDL is critical in human cortical development via regulation of mitochondrial functional properties

Human brain development is highly regulated by several spatiotemporal processes, which disruption can result in severe neurological disorders. Emerging evidence highlights the pivotal role of mitochondrial function as one of these fundamental pathways involved in neurodevelopment. Our study investigates the role of 4-hydroxyphenylpyruvate dioxygenase-like (HPDL) protein in cortical neurogenesis and mitochondrial activity, since mutations in the HPDL gene are associated with SPG83, a childhood-onset form of hereditary spastic paraplegia characterized by corticospinal tract degeneration and cortical abnormalities. Starting from mutant neuroblastoma cells, we demonstrated that HPDL is essential to mitochondrial respiratory chain supercomplex assembly and cellular redox balance. Moreover, transcriptomic analyses revealed dysregulated pathways related to neurogenesis, implicating HPDL role in early cortical development. To further elucidate the role of HPDL, we generated cortical neurons and organoids from SPG83 patient-derived induced pluripotent stem cells. Mutant cells exhibited premature neurogenesis at early differentiation stages, likely leading to depletion of cortical progenitors, as evidenced by decreased proliferation, slight increase of apoptosis, and unbalanced cortical type composition at later stages. Furthermore, cortical organoids derived from SPG83 patients showed impaired growth, reminding microcephaly observed in severe cases. In addition, mitochondrial morpho-functional characterization in mutant neurons confirmed disruption of OxPhos chain functionality and increased ROS generation rate. Treatment of cortical cells with two antioxidant compounds, could partially revert premature neurogenesis. In conclusion, our findings reveal a critical role for HPDL in coordinating cortical progenitor proliferation, neurogenesis, and mitochondrial function. These insights shed light on a mechanistical understanding of SPG83 pathology and underscore the therapeutic potential of targeting oxidative stress in this and related neurological disorders.

neuroscience↗

bioRxiv2024

Decreasing ganglioside synthesis delays motor and cognitive symptom onset in Spg11 knockout mice

Biallelic variants in the SPG11 gene account for the most common form of autosomal recessive hereditary spastic paraplegia characterized by motor and cognitive impairment, with currently no therapeutic option. We previously observed in a Spg11 knockout mouse that neurodegeneration is associated with accumulation of gangliosides in lysosomes. To test whether a substrate reduction therapy could be a therapeutic option, we downregulated the key enzyme involved in ganglioside biosynthesis using an AAV-PHP.eB viral vector expressing a miRNA targeting St3gal5. Downregulation of St3gal5 in Spg11 knockout mice prevented the accumulation of gangliosides, delayed the onset of motor and cognitive symptoms, and prevented the upregulation of serum levels of neurofilament light chain, a biomarker widely used in neurodegenerative diseases. Importantly, similar results were observed upon treatment of Spg11 knockout mice with venglustat, a pharmacological inhibitor of glucosylceramide synthase expected to decrease ganglioside synthesis. Downregulation of St3gal5 or venglustat treatment of Spg11 knockout mice strongly decreased the formation of axonal spheroids, previously associated with impaired trafficking. Venglustat had similar effect on cultured human SPG11 neurons. In conclusion, this work identifies the first disease-modifying therapeutic strategy in SPG11, and provides data supporting its relevance for therapeutic testing in SPG11 patients.

neuroscience↗

bioRxiv2019

Real-time sampling of travelers shows intestinal colonization by multidrug-resistant bacteria to be a dynamic process with multiple transient acquisitions

BackgroundAntimicrobial resistance (AMR) is highly prevalent in low- and middle-income countries (LMIC). International travel contributes substantially to the global spread of intestinal multidrug-resistant gram-negative (MDR-GN) bacteria. Of the 100 million annual visitors to LMIC, 30-70% become colonized by MDR-GN bacteria. The phenomenon has been well documented, but since sampling has only been conducted after travelers return home, data on the actual colonization process are scarce. We aimed to characterize colonization dynamics by exploring stool samples abroad on a daily basis while visiting LMIC. MethodsA group of 20 European volunteers visiting Lao Peoples Democratic Republic for three weeks provided daily stool samples and filled in daily questionnaires. Acquisition of extended-spectrum beta-lactamase-producing gram-negative bacteria (ESBL-GN) was examined by selective stool cultures followed by whole-genome sequencing (WGS) of isolates. ResultsWhile colonization rates were 70% at the end of the study, daily sampling revealed that all participants had acquired ESBL-GN at some time point during their overseas stay, the colonization status varying day by day. WGS analysis ascribed the transient pattern of colonization to sequential acquisition of new strains, resulting in a loss of detectable colonization by the initial MDR-GN strains. All but one participant acquired multiple strains (n=2-7). Of the total of 83 unique strains identified (53 E. coli, 10 Klebsiella, 20 other ESBL-GN species), some were shared by as many as four subjects. ConclusionsThis is the first study to characterize in real time the dynamics of acquiring MDR-GN during travel. Our data show multiple transient colonization events indicative of constant microbial competition.

microbiology↗