Biology subjects

RACHIDI, N.

Publications and source records attributed to RACHIDI, N..

3 recordsLinked to original sources

bioRxiv2026

Dynamic phosphoproteomics and proteomics uncover Leishmania donovani-driven ferritin hijacking, contributing to the control of iron homeostasis and iron-related oxidative stress

Leishmania donovani, the causative agent of visceral leishmaniasis, survives within the parasitophorous vacuole (PV) of mammalian macrophages by extensively rewiring host cellular pathways. Although transcriptional and proteomic changes in infected macrophages have been characterized, the impact on the host phosphoproteome, a pivotal, reversible regulator of signalling, remains largely unexplored. To address this gap, we combined time-resolved quantitative phosphoproteomics and proteomics to map the dynamic response of murine macrophages to L. donovani infection. Early after infection, the parasite rapidly attenuates the macrophage signaling cascades normally triggered by phagocytosis. Between 24 h and 48 h post-infection we observed a progressive de-phosphorylation of proteins involved in innate immunity, apoptosis and other stress-responsive pathways, consistent with a partial shutdown of multiple host kinases. From 24 h onward, a global decline in protein abundance was also detected, most notably within lysosomal network. Strikingly, only five host proteins were consistently up-regulated, suggesting their importance for parasite survival. Ferritin light chain (Ftl1) displayed the largest increase. Immunofluorescence and transmission-electron microscopy revealed that Ftl1 accumulates within the parasitophorous vacuole, colocalizes with the ferritin receptor Ncoa4, and yet fails to undergo degradation, indicating that Leishmania co-opts ferritin as its own intracellular iron-storage compartment. Ferritin is not confined to the PV; it is also internalized by the parasite. Within L. donovani, ferritin accumulates not only in the cytoplasm but also in the nucleus, where it may function both as an iron-storage depot and as an iron buffer that protects the parasite from oxidative damage. Finally, we demonstrate that Leishmania donovani pre-conditions its host macrophage for the iron-rich environments of the liver and spleen by driving the assembly of ferritin particles enriched in ferritin-light chain. This contrasts with L. amazonensis, which, residing in the iron-poor skin, induces ferritin predominated by ferritin-heavy chain (Fth1). Knock-down of Ftl1 did not decrease parasite survival because macrophages compensated for its loss by up-regulating Hspb1, which encodes a protein that limits lipid peroxidation by inhibiting the Fenton reaction. Although this response protects the host cell, it also diminishes iron import, imposing a metabolic cost on Leishmania. Hspb1 represents only one example; additional, as yet unidentified, compensatory pathways are likely activated by the parasite to mitigate the loss of ferritin-light chain. Collectively, our data uncover a previously unknown strategy whereby L. donovani hijacks host ferritin trafficking to create a protected iron reservoir, thereby preventing ferroptosis. This mechanism sets Leishmania, a eukaryotic intracellular parasite, apart from the canonical iron-acquisition tactics employed by bacteria and fungi.

microbiology↗

bioRxiv2025

Characterization of the dual functions of Leishmania CK1.2 in both the parasite and the macrophage using integrated proteomics and spatial mapping

Leishmania CK1.2 (L-CK1.2) is a serine/threonine protein kinase essential for the survival of the protozoan parasite Leishmania, the causative agent of Leishmaniasis. This study investigates the dynamic localization pattern of L-CK1.2 and the broad spectrum of its interacting partners within the parasite. Using proteomic analysis and confocal microscopy, we identified 230 L-CK1.2-associated proteins across the parasite life stages, promastigotes (in the insect vector), and amastigotes, (in the phagolysosomes of host macrophages). This analysis revealed the ubiquitous presence of L-CK1.2 in various cellular structures, including the cytoskeleton, basal body, and flagellum. Using an in vitro system, sixty-four host L-CK1.2-associated proteins, involved in critical host biological processes such as immune response, apoptosis, and purine biosynthesis, were shown to interact with L-CK1.2. These processes are known to be regulated by Leishmania during infection. The study highlights the dual function of L-CK1.2, in the parasite (cis) and within the host cell (trans), positioning this kinase as a key player in host-pathogen interactions. This work provides a comprehensive map of L-CK1.2 interactions and suggest its potential importance in regulating intracellular Leishmania survival, providing potential therapeutic targets for Leishmaniasis. Furthermore, given the evolutionary conservation of CK1.2 across other parasitic organisms, our findings may have broader implications for understanding and managing parasitic infections.

microbiology↗

bioRxiv2020

The low complexity regions in the C-terminus are essential for the subcellular localisation of Leishmania casein kinase 1 but not for its activity

Casein Kinase 1 (CK1) family members are serine/threonine protein kinases ubiquitously expressed in eukaryotic organisms. They are involved in a wide range of important cellular processes, such as membrane trafficking, or vesicular transport in organisms from yeast to humans. Due to its broad spectrum of action, CK1 activity and expression is tightly regulated by a number of mechanisms, including subcellular sequestration. Defects in CK1 regulation, localisation or the introduction of mutations in the CK1 coding sequence are often associated with important diseases such as cancer. Increasing evidence suggest that the manipulation of host cell CK1 signalling pathways by intracellular pathogens, either by exploiting the host CK1 or by exporting the CK1 of the pathogen into the host cell may play an important role in infectious diseases. Leishmania CK1.2 is essential for parasite survival and released into the host cell, playing an important role in host pathogen interactions. Although Leishmania CK1.2 has dual role in the parasite and in the host cell, nothing is known about its parasitic localisation and organelle-specific functions. In this study, we show that CK1.2 is a ubiquitous kinase, which is present in the cytoplasm, associated to the cytoskeleton and localised to various organelles, indicating potential roles in kinetoplast and nuclear segregation, as well as ribosomal processing and motility. Furthermore, using truncated mutants, we show for the first time that the two low complexity regions (LCR) present in the C-terminus of CK1.2 are essential for the subcellular localisation of CK1.2 but not for its kinase activity, whereas the deletion of the N-terminus leads to a dramatic decrease in CK1.2 abundance. In conclusion, our data on the localisation and regulation of Leishmania CK1.2 contribute to increase the knowledge on this essential kinase and get insights into its role in the parasite.

cell biology↗