Molecular characterization of the evolution of phagosomes

Abstract

First large-scale comparative proteomics/phosphoproteomics study characterizing some of the key steps that contributed to the remodeling of phagosomes that occurred during evolution. Comparison of profiling analyses of isolated phagosomes from three distant organisms (Dictyostelium, Drosophila, and mouse) revealed a protein core that defines a potential ‘ancient' phagosome and a set of 50 proteins that emerged while adaptive immunity was already well established.Gene duplication events of mouse phagosome paralogs occurred mostly in Bilateria and Euteleostomi, coinciding with the emergence of innate and adaptive immunity, and thus, provided the functional innovations needed for the establishment of these two crucial evolutionary steps of the immune system.Phosphoproteomics of isolated phagosomes from the same three distant species indicate that the phagosome phosphoproteome has been extensively modified during evolution. Still, some phosphosites have been maintained for >1.2 billion years, and thus, highlight their particular significance in the regulation of key phagosomal functions.

The Protein Tyrosine Phosphatase SHP-1 Regulates Phagolysosome Biogenesis

“…SHP-1 has previously been shown to associate with phagosomes, raising the possibility that it participates in the biogenesis of phagolysosomes (21,22). To investigate a potential role for SHP-1 in this process, we first performed confocal immunofluorescence experiments to visualize SHP-1 redistribution in murine BMM upon phagocytosis of serum-opsonized zymosan particles (27)(28)(29).…”

“…2D). To determine whether known SHP-1 substrates were differentially phosphorylated and recruited to phagosomes in the absence of SHP-1, we focused on Dok-1 (p62 Dok ), a major SHP-1 substrate (32) present in the phagosome proteome (22). Western blot analyses revealed that Dok-1 levels in phagosome lysates increased progressively over time, independently of the presence of SHP-1 (Fig.…”

“…In macrophages, SHP-1 participates in the regulation of various processes, including proinflammatory and innate immune responses (17)(18)(19)(20). SHP-1 has previously been shown to associate with phagosomes (21,22), thereby suggesting a role in the biogenesis of phagolysosomes. In this study, we present evidence that SHP-1 plays a role in phagosome maturation and that it is required for acidification of this organelle.…”

High‐resolution quantitative proteome analysis reveals substantial differences between phagosomes of RAW 264.7 and bone marrow derived macrophages

“…One of the main functions of macrophages is phagocytosis, which is the active uptake of large particles (> 0.5 μm) by cells 3. Phagocytosis is an important cellular mechanism for almost all eukaryotes, highly conserved from amoeba to human 4, in mammals, it is a key part of the innate immune response against invading microorganisms. Moreover, macrophages phagocytose apoptotic cells and cell debris to recycle cellular building blocks during homeostasis and development 5, 6.…”

“…In recent years, the cell line has also been used extensively in proteomics experiments including a large‐scale proteome 10, phagosome proteomics 4, 8, 11, responses to cytokines 12, 13, and identification of DNA receptors 14.…”