Elucidation of the composition and function of the protein corona in matrix vesicles (MVs): a new mechanism for controlling biomineralization?

• Grant number: 24/17743-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: March 01, 2025
• End date: February 29, 2028
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Pietro Ciancaglini
• Grantee: Larwsk Hayann Gonçalves da Silva
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 19/08568-2 - Investigation of the extracellular vesicles (VEs) role in the initiation, propagation, regeneration, and modeling of biological mineralization, AP.TEM

Abstract

Osteocompetent cells, such as hypertrophic chondrocytes, osteoblasts and odontoblasts, release a special class of extracellular vesicles called matrix vesicles (MVs) that are involved in the deposition of apatite minerals at the sites of bone and tooth calcification. During the formation of physiological and pathological calcifications, MVs are believed to be released by outward budding of the apical microvilli of osteocompetent cells, bind to collagen fibrils and initiate biomineralization by virtue of their biochemical machinery. The process of MV synthesis and release is still under debate. Currently, several studies demonstrate the similarity of proteins arranged in the lipid bilayer of MVs with those found in microvilli of the parental cells that gave rise to MVs. However, a recent study comparing the proteome of MV and apical microvilli isolated from osteoblast cell lines demonstrated that several of the MV proteins do not originate from microvilli. The same study suggests that after their release, proteins derived from the extracellular space (ECS) can adsorb and form a peripheral protein crown on the surface of MV, as occurs with nanoparticles in contact with the body environment. The biological role of this protein crown is still unknown. Thus, the complexity of the bone mineralization process and its regulatory processes lead to the main question of this project: What is the role of these proteins superficially adsorbed on MV? Would they be responsible for the selective binding of these vesicles to collagen fibrils? Do they have any impact on the cell-cell communication process? And how do they behave in ectopic (pathological) mineralization processes?The development of this postdoctoral project aims to elucidate the questions formulated above by studying the role of the protein crown present in MV. To this end, the lipid composition and physicochemical and biological properties of this highly complex and metabolically active vesicular structure will be characterized. The aim is to identify the ECS proteins that adsorb onto MVs released by (1) osteoblasts (MC3T3-E1 cell line), (2) mature osteoblasts isolated from calvaria, and (3) mouse long bones. In addition, we will investigate whether the proteins adsorbed post-release onto the ECS have biological functions that modulate the ability of vesicles to bind to collagen fibrils and initiate biomineralization. The development of the project will provide deep insights into a novel and unexplored aspect of MVs: their ability to function as collagen-anchored mineralization nanoreactors modulated by ECS proteins. This proposal has potential for biotechnological application, as it will also allow the development of diagnostic and therapeutic approaches for pathologies related to bone tissue and is an important complementary line of the Thematic Project (2019/08568-2), currently funded by FAPESP.