News from the Institute

Today, the German Research Foundation (DFG) announced the establishment of a new Research Unit (FOR 2625) on the mechanisms of lysosomal homeostasis.

The Unit is led by Thomas Braulke from the University Medical Center Hamburg-Eppendorf, with 13 research groups from Germany and one from The Netherlands taking part. From IBC2, Anja Bremm and Ivan Dikic are on board, bringing in their expertise in ubiqiuitin signaling and deciphering how ubiquitin regulates lysosome function.

Rahel de Bruyn from the Kaulich group is one of the winners of this years’ poster prize at the 8th Mildred Scheel Cancer Conference (MSCC) in Bonn. She was awarded for her outstanding work on the tumor suppressor RB1 which controls cell cycle entry.

If a cell is not ready for DNA replication, RB1 halts further progression of the cell cycle in G1 phase. Thereby, it prevents the replication of damaged DNA which may lead to detrimental mutations and cancer development, as seen in retinoblastoma patients who carry a mutated RB1 gene.

The endoplasmic reticulum (ER) is the cell’s largest and probably most versatile organelle. It consists of extended membrane structures, which are constantly remodeled to ensure functionality in all cellular states. Degradation of the ER is mediated by a specialized form of selective autophagy (ER-phagy), a process which is until now not very well understood.

An international team around Ivan Dikic has identified Reticulon 3 (the full-length form of RTN3) as a selective receptor which specifically triggers fragmentation of ER tubules and their delivery to lysosomes. The process requires the core autophagy machinery but is independent of FAM134B, the first ER-phagy receptor previously identified by Dikic’s group. FAM134B is responsible for targeting ER sheets rather than ER tubules.

This was the slogan of a public TEDx event in Zagreb, at which IBC2 director Ivan Dikic shared his thoughts about what can be learnt from bacteria. It was the largest Croatian TED event ever, full of enthusiasm, creativity and inspiration.

The 20 speakers came from many different areas of society, and all gave one major motivation message: boundaries can be broken if we just strive hard enough.

A team around Ivan Dikic and Mike Heilemann (Chemistry Department, Goethe University) gained unprecedented insight into the mechanism by which cells fight Salmonella infections. Upon intracellular invasion, bacteria are usually rapidly surrounded by a coat of ubiquitin, the function of which remained unclear until now.

Combining super-resolution microscopy with cell biological analysis, the researchers now discovered that distinct ubiquitin chains transform the bacterial surface into a molecular signalling platform. They were able to visualize the nanoscale distribution of different ubiquitin chains on the bacterial surface.