Publications

* joint first author # joint corresponding author

Most Recent Publications
Ferenc Molnár, Szabolcs Horvát, Ana R. Ribeiro Gomes, Jorge Martinez Armas, Botond Molnár, Robert F Hevner, Kenneth Knoblauch, Henry Kennedy, Zoltan Toroczkai
Predictability of cortico-cortical connections in the mammalian brain.
Network Neuroscience, 8(1) 138-157 (2024)
Open Access DOI
Despite a five order of magnitude range in size, the brains of mammals share many anatomical and functional characteristics that translate into cortical network commonalities. Here we develop a machine learning framework to quantify the degree of predictability of the weighted interareal cortical matrix. Partial network connectivity data were obtained with retrograde tract-tracing experiments generated with a consistent methodology, supplemented by projection length measurements in a nonhuman primate (macaque) and a rodent (mouse). We show that there is a significant level of predictability embedded in the interareal cortical networks of both species. At the binary level, links are predictable with an area under the ROC curve of at least 0.8 for the macaque. Weighted medium and strong links are predictable with an 85%-90% accuracy (mouse) and 70%-80% (macaque), whereas weak links are not predictable in either species. These observations reinforce earlier observations that the formation and evolution of the cortical network at the mesoscale is, to a large extent, rule based. Using the methodology presented here, we performed imputations on all area pairs, generating samples for the complete interareal network in both species. These are necessary for comparative studies of the connectome with minimal bias, both within and across species. Revealed by tract-tracing datasets, communication between the functional areas of the cortex operates via a complex, dense, and weighted network of physical connections with little apparent regularity. Although there are studies showing the existence of nonrandom topological features, their extent has not been clear. Employing a machine learning-based approach, which efficiently extracts structural models from such datasets, here we show that there is a significant amount of regularity embedded in the mammalian connectome. This regularity allows predicting interareal connections and their weights with good accuracy and can be used to infer properties of experimentally untested connections. The structural models are well learned even with small training sets, without overfitting, suggesting the existence of a low-dimensional, universal mechanism for mesoscale cortical network formation and evolution.


Paula Cubillos, Nora Ditzer, Annika Kolodziejczyk, Gustav Schwenk, Janine Hoffmann, Theresa M Schütze, Razvan Derihaci, Cahit Birdir, Johannes Em Köllner, Andreas Petzold, Mihail Sarov, Ulrich Martin, Katherine S. Long, Pauline Wimberger, Mareike Albert
The growth factor EPIREGULIN promotes basal progenitor cell proliferation in the developing neocortex.
EMBO J, Art. No. doi: 10.1038/s44318-024-00068-7 (2024)
Open Access DOI
Neocortex expansion during evolution is linked to higher numbers of neurons, which are thought to result from increased proliferative capacity and neurogenic potential of basal progenitor cells during development. Here, we show that EREG, encoding the growth factor EPIREGULIN, is expressed in the human developing neocortex and in gorilla cerebral organoids, but not in the mouse neocortex. Addition of EPIREGULIN to the mouse neocortex increases proliferation of basal progenitor cells, whereas EREG ablation in human cortical organoids reduces proliferation in the subventricular zone. Treatment of cortical organoids with EPIREGULIN promotes a further increase in proliferation of gorilla but not of human basal progenitor cells. EPIREGULIN competes with the epidermal growth factor (EGF) to promote proliferation, and inhibition of the EGF receptor abrogates the EPIREGULIN-mediated increase in basal progenitor cells. Finally, we identify putative cis-regulatory elements that may contribute to the observed inter-species differences in EREG expression. Our findings suggest that species-specific regulation of EPIREGULIN expression may contribute to the increased neocortex size of primates by providing a tunable pro-proliferative signal to basal progenitor cells in the subventricular zone.


Adrian Pascal Nievergelt#, Dennis R Diener, Aliona Bogdanova, Thomas Brown, Gaia Pigino#
Protocol for precision editing of endogenous Chlamydomonas reinhardtii genes with CRISPR-Cas.
STAR Protoc, 5(1) Art. No. 102774 (2024)
Open Access DOI
CRISPR-Cas genome engineering in the unicellular green algal model Chlamydomonas reinhardtii has until recently suffered from low integration efficiencies despite traditional genetics being well established. Here, we present a protocol for efficient homology-directed knockin mutagenesis in all commonly used strains of Chlamydomonas. We describe steps for scarless integration of fusion tags and sequence modifications of almost all proteins without the need for a preceding mutant line. We further empower this genetic-editing approach by efficient crossing and highly robust screening protocols. For complete details on the use and execution of this protocol, please refer to Nievergelt et al. (2023).1.


Maja Illig✳︎, Kevin Jahnke✳︎, Lukas P Weise✳︎, Marlene Scheffold, Ulrike Mersdorf, Hauke Drechsler, Yixin Zhang, Stefan Diez#, Jan Kierfeld#, Kerstin Göpfrich#
Triggered contraction of self-assembled micron-scale DNA nanotube rings.
Nat Commun, 15(1) Art. No. 2307 (2024)
Open Access DOI
Contractile rings are formed from cytoskeletal filaments during cell division. Ring formation is induced by specific crosslinkers, while contraction is typically associated with motor protein activity. Here, we engineer DNA nanotubes and peptide-functionalized starPEG constructs as synthetic crosslinkers to mimic this process. The crosslinker induces bundling of ten to hundred DNA nanotubes into closed micron-scale rings in a one-pot self-assembly process yielding several thousand rings per microliter. Molecular dynamics simulations reproduce the detailed architectural properties of the DNA rings observed in electron microscopy. Theory and simulations predict DNA ring contraction - without motor proteins - providing mechanistic insights into the parameter space relevant for efficient nanotube sliding. In agreement between simulation and experiment, we obtain ring contraction to less than half of the initial ring diameter. DNA-based contractile rings hold promise for an artificial division machinery or contractile muscle-like materials.


Mukesh Kumar, Canan Has, Khanh Lam-Kamath, Sophie Ayciriex, Deepshe Dewett, Mina Bashir, Clara Poupault, Kai Schuhmann, Henrik Thomas, Oskar Knittelfelder, Bharath Kumar Raghuraman, R Ahrends, Jens Rister#, Andrej Shevchenko#
Lipidome Unsaturation Affects the Morphology and Proteome of the Drosophila Eye.
J Proteome Res, Art. No. doi: 10.1021/acs.jproteome.3c00570 (2024)
Open Access DOI
Organisms respond to dietary and environmental challenges by altering the molecular composition of their glycerolipids and glycerophospholipids (GPLs), which may favorably adjust the physicochemical properties of lipid membranes. However, how lipidome changes affect the membrane proteome and, eventually, the physiology of specific organs is an open question. We addressed this issue in Drosophila melanogaster, which is not able to synthesize sterols and polyunsaturated fatty acids but can acquire them from food. We developed a series of semisynthetic foods to manipulate the length and unsaturation of fatty acid moieties in GPLs and singled out proteins whose abundance is specifically affected by membrane lipid unsaturation in the Drosophila eye. Unexpectedly, we identified a group of proteins that have muscle-related functions and increased their abundances under unsaturated eye lipidome conditions. In contrast, the abundance of two stress response proteins, Turandot A and Smg5, is decreased by lipid unsaturation. Our findings could guide the genetic dissection of homeostatic mechanisms that maintain visual function when the eye is exposed to environmental and dietary challenges.


Joshua Mills, L Johanna Gebhard, Florence Schubotz, Anna Shevchenko, Daan R Speth, Yan Liao, Iain G Duggin, Anita Marchfelder, Susanne Erdmann
Extracellular vesicle formation in Euryarchaeota is driven by a small GTPase.
Proc Natl Acad Sci U.S.A., 121(10) Art. No. e2311321121 (2024)
Open Access DOI
Since their discovery, extracellular vesicles (EVs) have changed our view on how organisms interact with their extracellular world. EVs are able to traffic a diverse array of molecules across different species and even domains, facilitating numerous functions. In this study, we investigate EV production in Euryarchaeota, using the model organism Haloferax volcanii. We uncover that EVs enclose RNA, with specific transcripts preferentially enriched, including those with regulatory potential, and conclude that EVs can act as an RNA communication system between haloarchaea. We demonstrate the key role of an EV-associated small GTPase for EV formation in H. volcanii that is also present across other diverse evolutionary branches of Archaea. We propose the name, ArvA, for the identified family of archaeal vesiculating GTPases. Additionally, we show that two genes in the same operon with arvA (arvB and arvC) are also involved in EV formation. Both, arvB and arvC, are closely associated with arvA in the majority of other archaea encoding ArvA. Our work demonstrates that small GTPases involved in membrane deformation and vesiculation, ubiquitous in Eukaryotes, are also present in Archaea and are widely distributed across diverse archaeal phyla.


Michaela Wilsch-Bräuninger#, Jula Peters, Wieland Huttner#
High-resolution 3D ultrastructural analysis of developing mouse neocortex reveals long slender processes of endothelial cells that enter neural cells.
Front Cell Dev Biol, 12 Art. No. 1344734 (2024)
Open Access DOI
The development of the neocortex involves an interplay between neural cells and the vasculature. However, little is known about this interplay at the ultrastructural level. To gain a 3D insight into the ultrastructure of the developing neocortex, we have analyzed the embryonic mouse neocortex by serial block-face scanning electron microscopy (SBF-SEM). In this study, we report a first set of findings that focus on the interaction of blood vessels, notably endothelial tip cells (ETCs), and the neural cells in this tissue. A key observation was that the processes of ETCs, located either in the ventricular zone (VZ) or subventricular zone (SVZ)/intermediate zone (IZ), can enter, traverse the cytoplasm, and even exit via deep plasma membrane invaginations of the host cells, including apical progenitors (APs), basal progenitors (BPs), and newborn neurons. More than half of the ETC processes were found to enter the neural cells. Striking examples of this ETC process "invasion" were (i) protrusions of apical progenitors or newborn basal progenitors into the ventricular lumen that contained an ETC process inside and (ii) ETC process-containing protrusions of neurons that penetrated other neurons. Our observations reveal a - so far unknown - complexity of the ETC-neural cell interaction.


Katarzyna P Adamala#, Marileen Dogterom#, Yuval Elani#, Petra Schwille#, Masahiro Takinoue#, T-Y Dora Tang#
Present and future of synthetic cell development.
Nat Rev Mol Cell Biol, 25(3) 162-167 (2024)
DOI


Mengfei Gao, Dishi Wang, Michaela Wilsch-Bräuninger, Weihua Leng, Jonathan Schulte, Nina Morgner, Dietmar Appelhans, T-Y Dora Tang
Cell Free Expression in Proteinosomes Prepared from Native Protein-PNIPAAm Conjugates.
Macromol Biosci, 24(3) Art. No. e2300464 (2024)
Open Access DOI
Towards the goal of building synthetic cells from the bottom-up, the establishment of micrometer-sized compartments that contain and support cell free transcription and translation that couple cellular structure to function is of critical importance. Proteinosomes, formed from crosslinked cationized protein-polymer conjugates offer a promising solution to membrane-bound compartmentalization with an open, semi-permeable membrane. Critically, to date, there has been no demonstration of cell free transcription and translation within water-in-water proteinosomes. Herein, a novel approach to generate proteinosomes that can support cell free transcription and translation is presented. This approach generates proteinosomes directly from native protein-polymer (BSA-PNIPAAm) conjugates. These native proteinosomes offer an excellent alternative as a synthetic cell chassis to other membrane bound compartments. Significantly, the native proteinosomes are stable under high salt conditions that enables the ability to support cell free transcription and translation and offer enhanced protein expression compared to proteinosomes prepared from traditional methodologies. Furthermore, the integration of native proteinosomes into higher order synthetic cellular architectures with membrane free compartments such as liposomes is demonstrated. The integration of bioinspired architectural elements with the central dogma is an essential building block for realizing minimal synthetic cells and is key for exploiting artificial cells in real-world applications.


Cedric Landerer, Jonas Pöhls, Agnes Toth-Petroczy
Fitness effects of phenotypic mutations at proteome-scale reveal optimality of translation machinery.
Mol Biol Evol, Art. No. doi: 10.1093/molbev/msae048 (2024)
Open Access DOI
Errors in protein translation can lead to non-genetic, phenotypic mutations, including amino acid misincorporations. While phenotypic mutations can increase protein diversity, the systematic characterization of their proteome-wide frequencies and their evolutionary impact has been lacking. Here, we developed a mechanistic model of translation errors to investigate how selection acts on protein populations produced by amino acid misincorporations. We fitted the model to empirical observations of misincorporations obtained from over a hundred mass spectrometry datasets of E. coli and S. cerevisiae. We found that on average 20-23% of proteins synthesized in the cell are expected to harbour at least one amino acid misincorporation, and that deleterious misincorporations are less likely to occur. Combining misincorporation probabilities and the estimated fitness effects of amino acid substitutions in a population genetics framework, we found 74% of mistranslation events in E. coli and 94% in S. cerevisiae to be neutral. We further show that the set of available synonymous tRNAs is subject to evolutionary pressure, as the presence of missing tRNAs would increase codon-anticodon cross-reactivity and misincorporation error rates. Overall, we find that the translation machinery is likely optimal in E. coli and S. cerevisiae and that both local solutions at the level of codons and a global solution such as the tRNA pool can mitigate the impact of translation errors. We provide a framework to study the evolutionary impact of codon specific translation errors and a method for their proteome-wide detection across organisms and conditions.

Silke Thüm

Head Librarian

Silke Thüm

Head Librarian
thuem@mpi-cbg.de
+49 351 210-2625