Pertz Lab

Homeostasis patterning

ERK activity dynamics in epithelial homeostasis (left) versus stem cell developmental patterning (right). Color-coded ERK activity dynamics are shown in segmented nuclei of breast epithelial MCF10A cells in which death has been induced by doxorubicin (left) or in H9 stem cells growing as a colony in pluripotency medium (right).

Human stem cells on a disc

E9 human embryonal stem cells cultivated on 1 mm wide geltrex disc in E8_flex medium. Stem cells express an ERK biosensor and a nuclear marker. Nuclei are color-coded with warm/cold colors indicating high/low ERK activity. Note a band of constant width of cells at the periphery of the colony that display high ERK activity, while the cells at the cell center display low ERK activity. Note the sharp boundary between the two zones of high and low ERK activity.

Interactive data visualisation for stem cell colonies

Segmentation, tracks, and single-cell signalling activity can all be interactively displayed in the Napari image viewer. This facilitates the exploration and combination of different data modalities to uncover new patterns within the data.

ERK/AKT activity waves during collective migration of breast cancer cells (+Alpelisib)

MCF10A cells on circular micropattern

Cells are confined on a micropattern over 4 days. The circle is coated with adhesive fibronectin, while the surrounding area is passivated with PLL-g-PEG.

Cell death-triggered ERK activity waves in an epithelial monolayer

A movie showing waves of ERK activity triggered by apoptotic events in a MDCK epithelial monolayer in vitro. These MDCK cells are a gift of Kazuhiro Aoki and have been engineered to express the FRET biosensor EKAREV-NLS (Ref: Hino et al, Dev Cell, 2020). The time lapse movie was acquired by Paolo A Gagliardi under gentle apoptosis induction with doxorubicin and shows FRET/CFP ratio (cold colors: low ERK activity; warm colors: high ERK activity).

ERK/AKT activity waves during collective migration of breast cancer cells

Image processing pipeline to analyse spatio-temporal dynamics in cell signalling

Our image quantification pipeline at Pertz Lab goes beyond population means & single-cell time series. An apoptotic cell in MDCK cells induces a wave of ERK activity. We can now detect such space-time correlations with ARCOS.

ERK dynamics visualized in a 3D epithelial acinus

Movie showing ERK activity of single cells in a stage 2 MCF10A acinus with a KTR biosensor.

• Top left: H2B - miRFP channel.

• Bottom left: H2B - miRFP channel with nuclear segmentation overlaid as wireframes.

• Top middle: ERK KTR - mTurquoise channel. Bottom middle: Nuclear segmentations are color-coded according to ERK activity. Dark/bright grey shades indicate low/high ERK activity respectively.

• Right: detrended and normalized ERK activity trajectory of the cell labeled 6. This 3D reconstruction was produced with LEVERJS.

realtime optogenetic control of Rac activity in a fibroblast

Real-time segmentation of fibroblasts allows us to grow the actin skeleton in a specified direction. The cells express an optogenetic construct to activate RAC. For segmentation we use a custom a pixel classifier that can be trained on live data from the microscope at the beginning of the experiment.

realtime control of cell migration using an optogenetic FGFR receptor

NIH3T3 cells are transfected with an optogenetic actuator for FGFR. During the experiment the cell is tracked using a nuclear marker (H2B), and the illumination region is automatically updated to always shine light above the nucleus, making the cell migrate in an upwards direction.

Realtime segmentation of epithelial cells

Using a nuclear marker and GPU accelerated image processing, these epithelial cells are segmented in realtime (~2FPS), and the resulting labels are displayed in Napari.