The Roles and Regulation of Protein Phase Separation in Immune Responses and Aging

Life originates from the assembly of disordered matter into organized structures. Understanding how simple biological components self-assemble into complex living systems is one of the most fascinating and fundamental questions in biology. Over the last decade, through my work at ETH Zürich, Harvard University, and the University of Cambridge, my research focused on elucidating the principles of how biological matter, particularly proteins, self-assemble into macromolecular structures, specifically via protein phase separation and aggregation.

Protein phase separation and aggregation consist in the segregation and concentration of proteins into distinct compartments, known as protein condensates, which may exhibit liquid-like, gel-like, or solid properties. These condensates are essential for cellular organization and regulate a wide array of cellular processes, including DNA replication and repair, cellular metabolism, stress responses, and immune functions. However, aberrant phase separation is also a hallmark of widespread human conditions, such as aging-related neurodegenerative diseases like Alzheimer’s or Parkinson’s, infectious and autoimmune diseases, and cancer. Thus, understanding phase separation is crucial for both advancing fundamental biology and developing novel therapeutic strategies.

My overarching goal is to understand how protein phase separation contributes to regulating physiological and pathological processes, elucidating fundamental questions such as:

• Functions: What are the physiological functions of protein phase separation?

• Mechanisms: Which molecular mechanisms control this process? How does it become pathological?

• Therapeutic Interventions: How can we modulate protein phase separation to target diseases?

Specifically, the goal of my Ambizione project is to study these key questions in two biomedically relevant areas: immune responses and aging. This project builds on my recent work on cytokine phase separation and protein aggregation in cellular stress response (Cereghetti et al., Nature Cell Biology, 2021; Cereghetti et al. Dev. Cell, 2024; Diaz-Barreiro*, Cereghetti*, et al., Cell Reports, 2024) and is structured into two specific aims:

1.Cytokines: Unravel the role and regulation of cytokine phase separation in immune responses and aging

2.Antimicrobial Peptides (AMPs): Investigate the mechanisms and roles of phase-separating AMPs

To achieve these aims, my multidisciplinary research plan employs cell biological and biochemical approaches I mastered during my PhD at ETH Zürich, combined with the computational and high-throughput droplet-based microfluidic technologies I developed during my Postdoc at the University of Cambridge, to investigate protein phase separation from the molecular to the cellular level.

In summary, understanding the processes underlying protein phase separation and aggregation has wide-ranging implications across multiple fields. By investigating protein condensates in the context of immune responses and aging, this Ambizione project will not only provide essential insights into fundamental biology, but also open new avenues for therapeutic interventions targeting aberrant phase separation. This vibrant and rapidly growing field provides the ideal conditions for a young independent group to produce excellent science and contribute to breakthrough discoveries, thereby catalyzing my personal career development.