Author Archives: chrhe74

Astroglial Resting Calcium Controls the Scale of Calcium Signals

Astroglia can encode their activity by the generation of Ca2+ signals, which then trigger or modify various functions of the cell. The signalling pathways that generate Ca2+ signals have been explored in detail. However, what controls their amplitude and waveform remains poorly understood. Using an array of optical methods in vitro and in vivo, we, i.e., Claire King, Kirsten Bohmbach and further colleagues have explored how the resting Ca2+ concentration controls these signals. We consistently find that peak and amplitude of Ca2+ signals display an opposite dependence on the resting Ca2+: a previously unrecognized basic rule underlying Ca2+ signalling in astroglial. The study has been published in Cell Report.

King CM, Bohmbach K, Minge D, Delekate A, Zheng K, Reynolds J, Rakers C, Zeug A, Petzold GC, Rusakov DA, Henneberger C (2020) Local Resting Ca2+ Controls the Scale of Astroglial Ca2+ Signals. Cell Rep. 30(10):3466-3477 (link, open access)

Astroglial gap junctions and potassium buffering

Astrocytes form networks in which individual astrocytes are coupled to their neighbors via gap junctions. These networks are thought to help buffering rises of extracellular potassium and thereby to control neuronal excitability. Björn Breithausen, a PhD student in our lab, and colleagues have tested if acute pharmacological blockade of gap junctions impairs potassium buffering. In contrast to our expectations, we found that blockade of gap junctions only affected very local and very large extracellular potassium increases, which are usually only found in brain diseases. The study was published in GLIA.

Breithausen B, Kautzmann S, Boehlen A, Steinhäuser C, Henneberger C (2020) Limited contribution of astroglial gap junction coupling to buffering of extracellular K+ in CA1 stratum radiatum. Glia. 68(5):918-931 (link, open access)

Two PhD studentships available

We are hiring! Two PhD studentships are currently available in the labs of Susanne Schoch, Dirk Dietrich and our own.  The aim is to develop new optical sensors for the NMDA receptor co-agonists D-serine and glycine and to visualize their signaling with already established and newly designed sensors. We will then dissect to what extent and by what mechanisms neurons and astrocytes provide NMDA receptors with either co-agonist in the rodent hippocampus and how they thereby shape synaptic plasticity. Please see here for the full text of the job advertisement.

Please have a look at one of our recent papers to get an idea of what the project is roughly about:

Zhang WH, Herde MK, Mitchell JA, Whitfield JH, Wulff AB, Vongsouthi V, Sanchez-Romero I, Gulakova PE, Minge D, Breithausen B, Schoch S, Janovjak H, Jackson CJ, Henneberger C (2018) Monitoring hippocampal glycine with the computationally designed optical sensor GlyFS. Nat. Chem. Biol. (link).

Bonn Brain3 Meeting 2019 – registration open

BonnBrain3 logog

The registration for next year’s Bonn Brain3 meeting is open!

This time we are taking part in the organization of the meeting and are happy to have brought together an impressive line-up of speakers. The meeting features Talks & Poster Sessions, Short Talks & Lightning Talks by Junior Scientists, Poster Prizes for Postdocs and PhD Students, a Neuroscience Art Competition and a Young Investigator Research Session.

Please click here for the poster or go to the Bonn Brain3 website.

Novel optical tool to visualize glycine signalling

GlyFS illustrationTogether with the lab of Colin Jackson at the Australian National University in Canberra, we have been able to design, characterize and use the novel optical glycine sensor GlyFS.  Using this sensor we could directly show that the levels of the inhibitory neurotransmitter and NMDA receptor co-agonists glycine decrease with postnatal age, increase in response to plasticity-inducing neuronal stimuli and display gradients between synaptic and extrasynaptic locations in the hippocampus.

The full paper can be found here.

Welcome to the lab

This is to welcome two new colleagues to the lab. Petr Unichenko is joining as a postdoctoral research fellow and Katharina Hill as a medical student.

Congratulations and bye-bye

Steffi's defenseCongratulations to Steffi for the glorious finish of her PhD thesis today. The final verdict after her defense, which for some reason included a short discussion of the sturgeon habenula, was a fully-deserved summa cum laude. Great!

Unfortunately for us, Steffi will also move on in a few days and leave the very cool ivory tower of science to work with Bayer.

Heparan sulfates and astrocytes

Just before the end 2016 we received the very welcome news that our study on the role of heparan sulfates got accepted for publication. Together with the lab of Alexander Dityatev we uncovered that heparan sulfates are required for the integrity of the axon initial segment of CA1 pyramidal cells. Their lack leads to reduced pyramidal cell excitability, reduced synaptic plasticity, altered theta oscillations in vivo and impaired context discrimination (link). The end of the year also saw the publication of a few other collaboration projects including the effect of dopamine on the Ca2+ signalling of hippocampal astrocytes (link) and the coupling properties of thalamic astrocytes (link) among others.

Please also see our selected Publications for more details.

New lab members and new lab picture

This is to welcome two new PhD students to the lab. Catia Domingos will be primarily working on molecular signals that acutely modify astrocyte morphology whereas Alberto Pauletti will look into the relationship between astrocyte morphology and astrocyte gap junction coupling.

And here is the group this autumn …