Cx43 promotes exocytosis of damaged lysosomes through actin remodelling

Domingues, Neuza; Catarino, Steve; Cristovao, Beatriz; Rodrigues, Lisa; Filomena, Carvalho; Sarmento, Maria J.; Zuzarte, Mónica; Almeida, Jani-Sofia; Fernandes, Fábio; Rodrigues-Santos, Paulo; Santos, Nuno C.; Korolchuk, Viktor I.; Gonçalves, Teresa; Milošević, Ira; Raimundo, Nuno; Girão, Henrique

doi:10.21203/rs.3.rs-2277227/v1

Cited by 1 publication

(5 citation statements)

References 95 publications

(77 reference statements)

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“…Here, we found that Cx43 is recruited to the expanding phagosome and promotes hyphal fold, possibly by anchoring Arp2. These findings are in accordance with our recent work showing that Cx43 is recruited to damaged lysosomes and promotes exocytosis through the remodeling of actin cytoskeleton ( 44 ). In this process, we found that Cx43 effect on actin rearrangement is dependent on Arp2 activity ( 44 ).…”

Section: Discussionsupporting

confidence: 94%

“…These findings are in accordance with our recent work showing that Cx43 is recruited to damaged lysosomes and promotes exocytosis through the remodeling of actin cytoskeleton ( 44 ). In this process, we found that Cx43 effect on actin rearrangement is dependent on Arp2 activity ( 44 ). Additionally, supporting our hypothesis, components from this actin nucleator protein were also identified in our STRING analysis, namely, actin-related protein 2/3 complex subunit 5 (ARCP5), a component of the Arp2/3 complex, and actin-related protein 2 (ACTR2), an ATP-binding component of the Arp2/3 complex, promoter of branched actin networks.…”

Section: Discussionsupporting

confidence: 94%

“…Given the importance of actin filaments in hyphal folding ( 31 ) and the recent reports associating Cx43 to changes in actin cytoskeleton architecture and intracellular trafficking ( 41 – 43 ), we hypothesized that Cx43 plays a role during C. albicans infection. To address this issue, we started by evaluating the recruitment of Cx43 to C. albicans containing phagosomes by confocal microscopy.…”

Section: Resultsmentioning

confidence: 99%

“…As mentioned earlier, nucleation of actin filaments is pivotal to promoting hyphal folding ( 31 ). Furthermore, it was previously reported that Cx43 ( 44 ) and its GJA1-20k isoform ( 42 ) modulate actin polymerization and stabilize filamentous actin. To decipher in more detail the mechanism whereby Cx43 promotes hyphal folding, we next investigated the presence of Cx43 in the actin rings surrounding the hypha.…”

Section: Resultsmentioning

confidence: 99%

“…This process leads to transient immobilization of organelles, repair of cortical damage, and the formation of actin-rich protrusions during cell spreading, cell migration, and wound healing ( 50 ). Thus, given the existing evidence associating cytosolic Ca 2+ increase with actin reorganization ( 43 , 51 ), it is plausible that the local increase of Ca 2+ released from damaged phagolysosomes can indeed impact the local actin polymerization necessary for hyphal folding.…”

Section: Discussionmentioning

confidence: 99%

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Cx43-mediated hyphal folding counteracts phagosome integrity loss during fungal infection

Cristovao,

Rodrigues,

Catarino

et al. 2023

Microbiol Spectr

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Phagolysosomes are crucial organelles during the elimination of pathogens by host cells. The maintenance of their membrane integrity is vital during stressful conditions, such as during Candida albicans infection. As the fungal hyphae grow, the phagolysosome membrane expands to ensure that the growing fungus remains entrapped. Additionally, actin structures surrounding the hyphae-containing phagosome were recently described to damage and constrain these pathogens inside the host vacuoles by inducing their folding. However, the molecular mechanism involved in the phagosome membrane adaptation during this extreme expansion process is still unclear. The main goal of this study was to unveil the interplay between phagosomal membrane integrity and folding capacity of C. albicans -infected macrophages. We show that components of the repair machinery are gradually recruited to the expanding phagolysosomal membrane and that their inhibition diminishes macrophage folding capacity. Through an analysis of an RNAseq data set of C. albicans- infected macrophages, we identified Cx43, a gap junction protein, as a putative player involved in the interplay between lysosomal homeostasis and actin-related processes. Our findings further reveal that Cx43 is recruited to expand phagosomes and potentiates the hyphal folding capacity of macrophages, promoting their survival. Additionally, we reveal that Cx43 can act as an anchor for complexes involved in Arp2-mediated actin nucleation during the assembly of actin rings around hyphae-containing phagosomes. Overall, this work brings new insights on the mechanisms by which macrophages cope with C. albicans infection ascribing to Cx43 a new noncanonical regulatory role in phagosome dynamics during pathogen phagocytosis. IMPORTANCE Invasive candidiasis is a life-threatening fungal infection that can become increasingly resistant to treatment. Thus, strategies to improve immune system efficiency, such as the macrophage response during the clearance of the fungal infection, are crucial to ameliorate the current therapies. Engulfed Candida albicans , one of the most common Candida species, is able to quickly transit from yeast-to-hypha form, which can elicit a phagosomal membrane injury and ultimately lead to macrophage death. Here, we extend the understanding of phagosome membrane homeostasis during the hypha expansion and folding process. We found that loss of phagosomal membrane integrity decreases the capacity of macrophages to fold the hyphae. Furthermore, through a bioinformatic analysis, we reveal a new window of opportunities to disclose the mechanisms underlying the hyphal constraining process. We identified Cx43 as a new weapon in the armamentarium to tackle infection by potentiating hyphal folding and promoting macrophage survival.

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Section: Discussionsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 94%