Biology subjects

Chiacchiaretta, M.

Publications and source records attributed to Chiacchiaretta, M..

5 recordsLinked to original sources

bioRxiv2025

Mycobacterium tuberculosis diversity and macrophage heterogeneity dictate phagosomal acidification

Therapies counteracting pathogen-induced immune modulation of the host responses represent a promising improvement for tuberculosis treatments. Despite the documented role of host immune heterogeneity and bacterial genotypic background in determining infection outcomes, their interplay remains largely uncharacterized. We investigate the Mycobacterium tuberculosis (MTB)-human macrophage interaction considering both macrophage phenotypic variability and MTB genetic diversity. Using single-cell techniques, we show how diverse MTB lineages fine-tune phagosome acidification differently based on macrophage phenotype (M1, M2), revealing very heterogeneous host-pathogen interactions. Our findings underscore the multiplicity of outcomes due to the combinatorial interplay between MTB lineages and macrophage phenotypes, which may have implications in proper design for host-directed therapies. IMPORTANCEThe intricate interplay among host, pathogen, and environmental factors significantly contributes to susceptibility and clinical presentation of tuberculosis. These multifaceted mechanisms are often overlooked in tuberculosis studies, hindering our comprehensive understanding of infection progression and impeding the development of effective host-directed therapies which offer benefits such as reduced drug resistance emergence and heightened host compatibility. Contrary to the prevailing hypothesis, the results observed in this study demonstrate the nuanced response of different M. tuberculosis lineages within distinct macrophage phenotypes in terms of phagosome acidification. The findings of our investigation delineate a crucial yet under-characterized aspect of tuberculosis pathogenesis, emphasizing how the interactions between different M. tuberculosis lineages and macrophage phenotypes could significantly influence the efficacy of host-directed therapies, particularly those targeting phagolysosomal maturation. More broadly, recognizing the impact of both M. tuberculosis and macrophage heterogeneity is paramount in the development of effective strategies to combat tuberculosis.

microbiology↗

bioRxiv2025

REST/NRSF phosphorylation by CaMKIV regulates its transcriptional repressor activity and half-life

REST is a repressor of a large cluster of neural genes that homeostatically regulates neural activity. However, whether REST can be regulated by Ca2+ and Ca2+-activated kinases is unknown. We investigated Ca2+/calmodulin-dependent protein kinases (CaMKs) as upstream regulators of REST fate and activity. We show that REST is phosphorylated by CaMKIV at Ser-322 site located within the linker between the 5th-6th Zn-finger domains. Phosphomimic REST mutant in Serine-322 decreased REST repressor activity and caused its transition from nucleus to cytosol, followed by degradation. Molecular dynamics simulations of the phosphomimic N-terminal REST and the DNA RE1 sequence revealed a sharp decrease in the stability of the REST-RE1 binding interface. Moreover, the homeostatic effects of CaMKIV on the amplitude of excitatory synaptic currents were inhibited by the genetic deletion of REST. The results demonstrate that CaMKIV phosphorylation has a crucial role in the homeostatic regulation of REST levels and repressor activity. TeaserCaMKIV phosphorylation homeostatically regulates the repressor activity of REST on neural genes and its half-life.

neuroscience↗

bioRxiv2024

Astrocytic metabolic control of orexinergic activity in the lateral hypothalamus regulates sleep and wake architecture

Neuronal activity undergoes significant changes during vigilance states, accompanied by an accommodation of energy demands. While the astrocyte-neuron lactate shuttle has shown that lactate is the primary energy substrate for sustaining neuronal activity in multiple brain regions, its role in regulating sleep/wake architecture is not fully understood. We manipulated the cell-specific expression of monocarboxylate transporters (MCTs), the major lactate transporters, to examine the involvement of astrocytic lactate supply in maintaining consolidated wakefulness. Our results demonstrate that reduced expression of MCT4 in astrocytes disrupts lactate supply to orexin neurons in the lateral hypothalamus (LH), impairing wakefulness stability. We also show that MCT2-mediated lactate uptake is necessary for maintaining tonic firing of orexinergic neurons and stabilizing wakefulness. Our findings provide both in vivo and in vitro evidence supporting the critical role of astrocyte-to-orexinergic neuron lactate shuttle in regulating proper sleep/wake stability-- a crucial step for maintaining physiological functions and overall well-being.

neuroscience↗

bioRxiv2020

The enhancement of activity rescues the establishment of Mecp2 null neuronal phenotypes

Mecp2 deficiency, the gene responsible for Rett syndrome (RTT), affects brain maturation by impairing neuronal activity, transcription and morphology. These three elements are physiologically linked in a feed-forward cycle where neuronal activity modulates transcription and morphology to further increase network maturity. We hypothesized that the reduced activity displayed by maturing Mecp2 null neurons during development could perturb such cycle, sustaining an improper transcriptional program that, ultimately, impairs neuronal maturation. Accordingly, we show that by enhancing activity within an early time window, Ampakine redirects, in vitro, the development of null neuronal networks towards more physiological routes. Similarly, the administration of the drug to newborn null offspring delays the progression of symptoms, significantly prolonging life span. Our data highlights the role of altered neuronal activity during the establishment of Mecp2 null networks and the importance of such early defects to the typically poor maturity of RTT brain functions in adulthood. We propose the existence of an "early molecular phase" of Rett syndrome, a detailed description of which might disclose relevant targets for new rescue treatments.

neuroscience↗

bioRxiv2017

Automated detection of Mycobacterial growth on 96-well plates for rapid and accurate Tuberculosis drug susceptibility testing

M. tuberculosis grows slowly and is challenging to work with experimentally compared with many other bacteria. Although microtitre plates have the potential to enable high-throughput phenotypic testing of M. tuberculosis, they can be difficult to read and interpret. Here we present a software package, the Automated Mycobacterial Growth Detection Algorithm (AMyGDA), that measures how much M. tuberculosis is growing in each well of a 96-well microtitre plate. The plate used here has serial dilutions of 14 anti-tuberculosis drugs, thereby permitting the minimum inhibitory concentrations (MICs) to be elucidated. The two participating laboratories each inoculated ten 96-well plates with the standard H37Rv reference strain and, after two weeks incubation, measured the MICs for all 14 drugs on each plate and took a photograph. By analysing the images, we demonstrate that AMyGDA is reproducible, and that the MICs measured are comparable to those measured by a laboratory scientist. AMyGDA software will be used by the Comprehensive Resistance Prediction for Tuberculosis: an International Consortium (CRyPTIC) to measure the drug susceptibility profile of a large number (> 30,000) of samples of M. tuberculosis from patients over the next few years.

microbiology↗