Membrane trafficking lab @ UiO

– The Schink lab –

Schink Lab Research

Research Overview

The Schink Lab investigates how cells establish, maintain, and remodel membrane trafficking systems to preserve cellular organization while adapting to changing conditions. We focus on how phosphoinositide lipids and small GTPases regulate vesicle identity transitions, nutrient uptake, membrane recycling, and host-pathogen interactions.

Membrane trafficking is a dynamic, self-organizing system in which vesicles constantly form, mature, and fuse, while maintaining distinct organelle identities. Vesicles must accurately acquire molecular identity codes — specific combinations of phosphoinositide lipids and Rab GTPases — to ensure correct targeting, cargo delivery, and organelle function. Disruptions in these systems contribute to cancer progression, infectious disease, and neurodegeneration.

We combine advanced live-cell imaging, CRISPR-based gene editing, mechanobiology, phosphoinositide manipulation, quantitative modeling, and computational image analysis to dissect how robust membrane identity is established and maintained.

Research Areas

Membrane Identity Transitions and Vesicle Robustness

Every vesicle formation event requires erasing the identity of its donor membrane and establishing a new one. We study how vesicles undergo these identity transitions while preventing formation of rogue or hybrid vesicles that would disrupt intracellular organization.

Our work shows that newly formed macropinosomes initially inherit plasma membrane identity markers (Rab8, PtdIns4P), but rapidly transition into endosomal identity states (Rab5, PtdIns3P), driven by activation of the class III PI3-kinase VPS34. Failure to activate VPS34 leads to identity collapse and vesicle disassembly.

Using endogenously tagged CRISPR reporter cell lines, live-cell 3D microscopy, and mathematical modeling, we track these transitions in real time and define how phosphoinositide dynamics serve as early instructive signals for identity conversion.

Lipid Signaling Control of Vesicle Maturation

Phosphoinositides act as master regulators of vesicle fate by recruiting protein effectors that control maturation, sorting, and cargo selection.

  • Phafin2 integrates early phosphoinositide signals to coordinate actin remodeling, vesicle closure, and maturation.
  • WDFY2 localizes to phosphoinositide-rich tubules, directing cargo recycling and modulating invasive behavior through SNARE interactions.
  • The Phafin2-JIP4 complex coordinates membrane tubulation and cytoskeletal remodeling to regulate recycling pathways.

These mechanisms allow cells to fine-tune cargo traffic and maintain membrane homeostasis across multiple organelles.

Mechanobiology of Vesicle Formation

Membrane trafficking is tightly controlled by physical forces, including membrane tension, cortical stiffness, and actin cytoskeleton remodeling. We apply micropatterning approaches to precisely control cell shape and define spatial zones permissive for macropinosome formation.

Through combined use of membrane tension sensors, phosphoinositide reporters, and optogenetic actin regulators, we dissect how physical membrane properties intersect with lipid signaling to control vesicle initiation and maturation.

Nutrient Scavenging via Macropinocytosis in Cancer

In nutrient-poor tumor microenvironments, cancer cells activate macropinocytosis to scavenge extracellular proteins as alternative nutrient sources. This process is especially prominent in KRAS-driven pancreatic cancer, where amino acid supply via macropinocytosis supports anabolic growth under metabolic stress.

Using pancreatic cancer-derived organoids, we investigate:

  • How phosphoinositide identity transitions stabilize macropinosome formation.
  • How nutrient sensing pathways (mTORC1/2) integrate metabolic signals to modulate macropinocytic activity.
  • How trafficking flexibility allows cells to dynamically adapt between feeding and invasive states depending on microenvironmental cues.

Interplay Between Nutrient Scavenging and Invasive Migration (“Drink-or-Drive” Model)

Cancer cells continuously balance nutrient acquisition and invasive migration depending on metabolic demands and environmental constraints. Both processes rely on actin-driven remodeling, but serve distinct adaptive roles.

  • Under nutrient-limiting conditions, cells activate macropinocytosis (“Drink”) to scavenge extracellular proteins and support metabolism.
  • If sufficient nutrients are available, cells prioritize growth locally.
  • When local nutrient acquisition becomes insufficient, cells switch to invasive migration (“Drive”) to explore new nutrient-rich environments.

This sequential model explains how cancer cells dynamically regulate feeding versus invasion, allowing flexible adaptation to fluctuating conditions within the tumor microenvironment.

Membrane Recycling and Tubular Sorting Domains

After internalization, vesicles must efficiently sort and recycle cargo. Tubular recycling domains serve as hubs where lipid identity, curvature sensing, and cytoskeletal remodeling integrate:

  • Phafin2-JIP4 tubules extract membrane from macropinosomes to recycle membrane components.
  • WDFY2-positive tubules couple lipid binding with SNARE-dependent cargo sorting, regulating recycling of matrix metalloproteinases and controlling invasive potential.

We employ CRISPR-based genetic screens and quantitative imaging to identify additional regulators of recycling fidelity and trafficking robustness.

Host-Pathogen Interactions and Vesicle Identity Hijacking

Pathogens exploit vesicle identity transitions to establish replicative niches:

  • Viruses (Ebola, poxviruses) hijack macropinocytosis and manipulate identity transitions to avoid degradation.
  • Bacteria (Salmonella) remodel host phosphoinositide metabolism to stabilize replication compartments.

We employ Virus-Like Particle (VLP) systems and bacterial invasion models to dissect host-pathogen interactions under controlled experimental conditions. These studies reveal both infection mechanisms and fundamental principles of host trafficking regulation.

Autophagy as a Membrane Remodeling System

Autophagy uses related membrane remodeling mechanisms to engulf damaged proteins and organelles. In collaborative work, we study how the ATPase DFCP1 regulates membrane constriction at phosphoinositide-rich omegasomes, driving autophagosome biogenesis.

These systems highlight shared membrane remodeling principles across endocytosis, macropinocytosis, and autophagy.

Our Experimental Approach

We integrate:

  • CRISPR/Cas9 genome editing for endogenous tagging and gene manipulation
  • Live-cell and super-resolution microscopy (light-sheet, diSPIM, SIM, DNA-PAINT)
  • Micropatterning & mechanobiology to probe membrane-cytoskeleton interactions
  • Optogenetic manipulation of lipid signaling and actin remodeling
  • High-content imaging combined with machine-learning vesicle classification
  • Functional CRISPR-based genetic screens
  • Organoid models and 3D matrix invasion assays

Translational Perspectives

By dissecting membrane trafficking at molecular and systems levels, we aim to:

  • Identify vulnerabilities in nutrient-scavenging tumors
  • Define regulators of metastatic adaptation
  • Elucidate pathogen entry mechanisms for antiviral and antimicrobial targeting
  • Explore trafficking failures involved in degenerative diseases