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Cervero, P.

Publications and source records attributed to Cervero, P..

4 recordsLinked to original sources

Drebrin forms a cortical hub that connects actin, microtubules, and clathrin for endocytic transport of β2 integrin

Using primary human macrophages, we analyze the molecular machinery that enables direct contact of microtubule +tips with podosomes, and its connection to clathrin-based endocytosis. We show that the podosome cap protein drebrin, together with its +tip-localized binding partner EB3, regulates podosome-microtubule contact. Importantly, drebrin depletion leads to reduced endocytosis, particularly of {beta}2 integrin at podosomes. This is based on drebri[n]s interaction with {beta}2 integrin, and its direct binding of clathrin heavy chain via a canonical clathrin box and a novel box, which we identify also in other mammalian proteins. Our data enable a model of the molecular machinery that regulates direct contact between podosomes and microtubule +tips. Moreover, we provide evidence for spatial selectivity in endocytosis of {beta} integrins, while also revealing a more general principle of endocytic trafficking regulation, through drebrin working as a multivalent, actin-based hub that links the clathrin system with microtubule-based transport.

cell biology↗

Phagocytic podosomes enable efficient uptake of Candida auris by primary human macrophages

The yeast Candida auris is an emerging pathogen of steadily increasing importance. Understanding the molecular mechanisms of C. auris uptake and intracellular processing by immune cells such as macrophages is thus critical for counteracting the spreading of respective infections. Here, we show that phagocytosis of C. auris cells by primary human macrophages involves the formation of dot-like F-actin-rich structures at C. auris-containing phagosomes that we characterize as phagocytic podosomes. We analyse the composition, architecture, and dynamics of these structures, showing that they constitute a specific and highly dynamic adaptation of the phagocytic actin network of macrophages. We also show that disruption of phagocytic podosomes is associated with reduced internalization of C. auris cells and delayed maturation of respective phagosomes. Our data provide novel insights into the uptake mechanism and cytoskeletal rearrangements upon internalization of Candida by immune cells, while also challenging the dogma of a generally uniform and continuous actin network within phagocytic cups. At the same time, we identify C. auris as the first pathophysiologically relevant target whose internalization involves the formation of phagocytic podosomes.

cell biology↗

Myo1e/f at the podosome base regulate podosome dynamics and promote macrophage migration

Cells of the monocyte lineage form specialized membrane-associated, actin-rich structures, called podosomes. Podosomes play important roles in cell adhesion and migration as well as the proteolytic degradation of the extracellular matrix. While podosomes are always closely associated with the plasma membrane, the structural components linking the podosome core, composed of branched actin, to the membrane are not fully understood. In this study we show that class I myosins, Myo1e and Myo1f, localize to a specific region of podosomes, underneath the podosome core and near the ventral plasma membrane, and that this localization is mainly mediated by the Myo1e/f TH2 domains. Respective knockdowns or knockouts of Myo1e/f lead to increased podosome size, altered turnover and lateral mobility, which is likely due to Myo1e/f regulating the attachment of core actin filaments to the plasma membrane. In addition, Myo1e/f double knockout macrophages were characterized by a reduction in 3D and 2D migration, even though these cells exhibited increased ability to degrade the extracellular matrix. Along with the other membrane-associated podosome components, such as the transmembrane proteins MT-MMP and CD44, and the GPI-anchored DNase X, Myo1e and Myo1f mark the membrane-proximal region of podosomes. We propose to label this region as the podosome "base", an additional substructure joining the current trifecta of the podosome cap, core, and ring.

cell biology↗

Cargo-specific recruitment in clathrin and dynamin-independent endocytosis

Spatially controlled, cargo-specific endocytosis is essential for development, tissue homeostasis, and cancer invasion and is often hijacked by viral infections 1. Unlike clathrin-mediated endocytosis, which exploits cargo-specific adaptors for selective protein internalization, the clathrin and dynamin-independent endocytic pathway (CLIC-GEEC, CG-pathway) has until now been considered a bulk internalization route for the fluid phase, glycosylated membrane proteins and lipids 2,3. Although the core molecular players of CG endocytosis have been recently defined, no cargo-specific adaptors are known and evidence of selective protein uptake into the pathway is lacking 3. Here, we identify the first cargo-specific adaptor for CG-endocytosis and demonstrate its clinical relevance in breast cancer progression. By combining unbiased molecular characterization and super-resolution imaging, we identified the actin-binding protein swiprosin-1 (EFHD2) as a cargo-specific adaptor regulating integrin internalization via the CG-pathway. Swiprosin-1 couples active Rab21-associated integrins with key components of the CG-endocytic machinery, IRSp53 and actin. Swiprosin-1 is critical for integrin endocytosis, but not for other CG-cargo and supports integrin-dependent cancer cell migration and invasion, with clinically relevant implications for breast cancer. Our results demonstrate a previously unknown cargo selectivity for the CG-pathway and opens the possibility to discover more adaptors regulating it.

cell biology↗