2024/04/19 by Fabian Ruperti, Monika Dzieciątkowska, M. Sabrina Pankey +4 · 1 voice
Biochemistry, Genetics and Molecular Biology · Immunology and Microbiology · Engineering · #Marine Sponges and Natural Products #Invertebrate Immune Response Mechanisms #Marine Biology and Environmental Chemistry
paper · pdf · doi:10.1101/2024.04.19.590289
openalex publication_date 2024/04/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
Abstract The discovery that sponges (Porifera) can fully regenerate from aggregates of dissociated cells launched them as one of the earliest experimental models for cell adhesion and allorecognition studies in animals. This process depends on an extracellular glycoprotein complex called the Aggregation Factor (AF). However, our understanding of how animal adhesion and allorecognition mechanisms first evolved is complicated by the fact that the known components of the AF are thought to be unique to sponges. We used label-free quantitative proteomics to identify additional AF components and interacting proteins in the classical model Clathria prolifera and compare them to proteins involved in cell interactions in Bilateria. Our results confirm MAFp3/p4 as the primary components of the AF, but implicate related proteins with calx-beta and wreath domains as additional components. Using AlphaFold, we unveiled close structural similarities of AF components to distant homologs in other animals, previously masked by the stark decay of sequence similarity. The wreath domain, believed to be unique to the AF, was predicted to contain a central beta-sandwich of the same organization as the vWFD domain in extracellular, gel-forming gly-coproteins in other animals. Additionally, we co-purified candidate AF-interacting proteins that share a conserved C-terminus, containing divergent Ig-like and Fn3 domains, a combination also known from IgCAMs. One of these, MAFAP1, may function to link the AF to the surface of cells. Our results highlight the existence of an ancient toolkit of conserved protein domains regulating cell-cell and cell-ECM interactions in all animals, and likely reflect a common origin of cell-adhesion and allorecognition.