RT Journal Article
SR Electronic
T1 Catabolism of lysosome-related organelles in color-changing spiders supports intracellular turnover of pigments
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.02.22.432296
DO 10.1101/2021.02.22.432296
A1 Florent Figon
A1 Ilse Hurbain
A1 Xavier Heiligenstein
A1 Sylvain Trépout
A1 Kadda Medjoubi
A1 Andrea Somogyi
A1 Cédric Delevoye
A1 Graça Raposo
A1 Jérôme Casas
YR 2021
UL http://biorxiv.org/content/early/2021/02/22/2021.02.22.432296.abstract
AB Pigment organelles of vertebrates belong to the lysosome-related organelle (LRO) family, of which melanin-producing melanosomes are the prototypes. While their anabolism has been extensively unraveled through the study of melanosomes in skin melanocytes, their catabolism remains poorly known. Here, we tap into the unique ability of crab spiders to reversibly change body coloration to examine the catabolism of their pigment organelles. By combining ultrastructural and metal analyses on high-pressure frozen integuments, we first assess whether pigment organelles of crab spiders belong to the LRO family and, second, how their catabolism is intracellularly processed. Using scanning-transmission electron microscopy, electron tomography and nanoscale Synchrotron-based scanning X-ray fluorescence, we show that pigment organelles possess ultrastructural and chemical hallmarks of LROs, including intraluminal vesicles and metal deposits, similar to melanosomes. Monitoring ultrastructural changes during bleaching suggests that the catabolism of pigment organelles involves the degradation and removal of their intraluminal content, possibly through lysosomal mechanisms. In contrast to skin melanosomes, anabolism and catabolism of pigments proceed within the same cell without requiring either cell death or secretion/phagocytosis. Our work hence provides support for the hypothesis that the endolysosomal system is fully functionalized for within-cell turnover of pigments, leading to functional maintenance under adverse conditions and phenotypic plasticity. First formulated for eye melanosomes in the context of human vision, the hypothesis of intracellular turnover of pigments gets unprecedented strong support from pigment organelles of spiders.Competing Interest StatementThe authors have declared no competing interest.