@phdthesis{13107,
  abstract     = {Within the human body, the brain exhibits the highest rate of energy consumption amongst all organs, with the majority of generated ATP being utilized to sustain neuronal activity. Therefore, the metabolism of the mature cerebral cortex is geared towards preserving metabolic homeostasis whilst generating significant amounts of energy. This requires a precise interplay between diverse metabolic pathways, spanning from a tissue-wide scale to the level of individual neurons. Disturbances to this delicate metabolic equilibrium, such as those resulting from maternal malnutrition
or mutations affecting metabolic enzymes, often result in neuropathological variants of neurodevelopment. For instance, mutations in SLC7A5, a transporter of metabolically essential large neutral amino acids (LNAAs), have been associated with autism and microcephaly. However, despite recent progress in the field, the extent of metabolic restructuring that occurs within the developing brain and the corresponding alterations in nutrient demands during various critical periods remain largely unknown. To investigate this, we performed metabolomic profiling of the murine cerebral cortex to characterize the metabolic state of the forebrain at different developmental stages. We found that the developing cortex undergoes substantial metabolic reprogramming, with specific sets of metabolites displaying stage-specific changes. According to our observations, we determined a distinct temporal period in postnatal development during which the cortex displays heightened reliance on LNAAs. Hence, using a conditional knock-out mouse model, we deleted Slc7a5 in neural cells, allowing us to monitor the impact of a perturbed neuronal metabolic state across multiple developmental stages of corticogenesis. We found that manipulating the levels of essential LNAAs in cortical neurons in vivo affects one particular perinatal developmental period critical for cortical network refinement. Abnormally low intracellular LNAA levels result in cell-autonomous alterations in neuronal lipid metabolism, excitability, and survival during this particular time window. Although most of the effects of Slc7a5 deletion on neuronal physiology are transient, derailment of these processes during this brief but crucial window leads to long-term circuit dysfunction in mice. In conclusion, out data indicate that the cerebral cortex undergoes significant metabolic reorganization during development. This process involves the intricate integration of multiple metabolic pathways to ensure optimal neuronal function throughout different developmental stages. Our findings offer a paradigm for understanding how neurons synchronize the expression of nutrient-related genes with their activity to allow proper brain maturation. Further, our results demonstrate that disruptions in these precisely calibrated metabolic processes during critical periods of brain development may result in neuropathological outcomes in mice and in humans.},
  author       = {Knaus, Lisa},
  issn         = {2663 - 337X},
  pages        = {147},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{The metabolism of the developing brain : How large neutral amino acids modulate perinatal neuronal excitability and survival}},
  doi          = {10.15479/at:ista:13107},
  year         = {2023},
}

@misc{13126,
  abstract     = {Mapping the complex and dense arrangement of cells and their connectivity in brain tissue demands nanoscale spatial resolution imaging. Super-resolution optical microscopy excels at visualizing specific molecules and individual cells but fails to provide tissue context. Here, we developed Comprehensive Analysis of Tissues across Scales (CATS), a technology to densely map brain tissue architecture from millimeter regional to nanometer synaptic scales in diverse chemically fixed brain preparations, including rodent and human. CATS uses fixation-compatible extracellular labeling and optical imaging, including stimulated emission depletion or expansion microscopy, to comprehensively delineate cellular structures. It enables three-dimensional reconstruction of single synapses and mapping of synaptic connectivity by identification and analysis of putative synaptic cleft regions. Applying CATS to the mouse hippocampal mossy fiber circuitry, we reconstructed and quantified the synaptic input and output structure of identified neurons. We furthermore demonstrate applicability to clinically derived human tissue samples, including formalin-fixed paraffin-embedded routine diagnostic specimens, for visualizing the cellular architecture of brain tissue in health and disease.},
  author       = {Danzl, Johann G},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Research data for the publication "Imaging brain tissue architecture across millimeter to nanometer scales"}},
  doi          = {10.15479/AT:ISTA:13126},
  year         = {2023},
}

@article{13267,
  abstract     = {Three-dimensional (3D) reconstruction of living brain tissue down to an individual synapse level would create opportunities for decoding the dynamics and structure–function relationships of the brain’s complex and dense information processing network; however, this has been hindered by insufficient 3D resolution, inadequate signal-to-noise ratio and prohibitive light burden in optical imaging, whereas electron microscopy is inherently static. Here we solved these challenges by developing an integrated optical/machine-learning technology, LIONESS (live information-optimized nanoscopy enabling saturated segmentation). This leverages optical modifications to stimulated emission depletion microscopy in comprehensively, extracellularly labeled tissue and previous information on sample structure via machine learning to simultaneously achieve isotropic super-resolution, high signal-to-noise ratio and compatibility with living tissue. This allows dense deep-learning-based instance segmentation and 3D reconstruction at a synapse level, incorporating molecular, activity and morphodynamic information. LIONESS opens up avenues for studying the dynamic functional (nano-)architecture of living brain tissue.},
  author       = {Velicky, Philipp and Miguel Villalba, Eder and Michalska, Julia M and Lyudchik, Julia and Wei, Donglai and Lin, Zudi and Watson, Jake and Troidl, Jakob and Beyer, Johanna and Ben Simon, Yoav and Sommer, Christoph M and Jahr, Wiebke and Cenameri, Alban and Broichhagen, Johannes and Grant, Seth G.N. and Jonas, Peter M and Novarino, Gaia and Pfister, Hanspeter and Bickel, Bernd and Danzl, Johann G},
  issn         = {1548-7105},
  journal      = {Nature Methods},
  pages        = {1256--1265},
  publisher    = {Springer Nature},
  title        = {{Dense 4D nanoscale reconstruction of living brain tissue}},
  doi          = {10.1038/s41592-023-01936-6},
  volume       = {20},
  year         = {2023},
}

@article{14257,
  abstract     = {Mapping the complex and dense arrangement of cells and their connectivity in brain tissue demands nanoscale spatial resolution imaging. Super-resolution optical microscopy excels at visualizing specific molecules and individual cells but fails to provide tissue context. Here we developed Comprehensive Analysis of Tissues across Scales (CATS), a technology to densely map brain tissue architecture from millimeter regional to nanometer synaptic scales in diverse chemically fixed brain preparations, including rodent and human. CATS uses fixation-compatible extracellular labeling and optical imaging, including stimulated emission depletion or expansion microscopy, to comprehensively delineate cellular structures. It enables three-dimensional reconstruction of single synapses and mapping of synaptic connectivity by identification and analysis of putative synaptic cleft regions. Applying CATS to the mouse hippocampal mossy fiber circuitry, we reconstructed and quantified the synaptic input and output structure of identified neurons. We furthermore demonstrate applicability to clinically derived human tissue samples, including formalin-fixed paraffin-embedded routine diagnostic specimens, for visualizing the cellular architecture of brain tissue in health and disease.},
  author       = {Michalska, Julia M and Lyudchik, Julia and Velicky, Philipp and Korinkova, Hana and Watson, Jake and Cenameri, Alban and Sommer, Christoph M and Amberg, Nicole and Venturino, Alessandro and Roessler, Karl and Czech, Thomas and Höftberger, Romana and Siegert, Sandra and Novarino, Gaia and Jonas, Peter M and Danzl, Johann G},
  issn         = {1546-1696},
  journal      = {Nature Biotechnology},
  publisher    = {Springer Nature},
  title        = {{Imaging brain tissue architecture across millimeter to nanometer scales}},
  doi          = {10.1038/s41587-023-01911-8},
  year         = {2023},
}

@article{12802,
  abstract     = {Little is known about the critical metabolic changes that neural cells have to undergo during development and how temporary shifts in this program can influence brain circuitries and behavior. Inspired by the discovery that mutations in SLC7A5, a transporter of metabolically essential large neutral amino acids (LNAAs), lead to autism, we employed metabolomic profiling to study the metabolic states of the cerebral cortex across different developmental stages. We found that the forebrain undergoes significant metabolic remodeling throughout development, with certain groups of metabolites showing stage-specific changes, but what are the consequences of perturbing this metabolic program? By manipulating Slc7a5 expression in neural cells, we found that the metabolism of LNAAs and lipids are interconnected in the cortex. Deletion of Slc7a5 in neurons affects the postnatal metabolic state, leading to a shift in lipid metabolism. Additionally, it causes stage- and cell-type-specific alterations in neuronal activity patterns, resulting in a long-term circuit dysfunction.},
  author       = {Knaus, Lisa and Basilico, Bernadette and Malzl, Daniel and Gerykova Bujalkova, Maria and Smogavec, Mateja and Schwarz, Lena A. and Gorkiewicz, Sarah and Amberg, Nicole and Pauler, Florian and Knittl-Frank, Christian and Tassinari, Marianna and Maulide, Nuno and Rülicke, Thomas and Menche, Jörg and Hippenmeyer, Simon and Novarino, Gaia},
  issn         = {0092-8674},
  journal      = {Cell},
  keywords     = {General Biochemistry, Genetics and Molecular Biology},
  number       = {9},
  pages        = {1950--1967.e25},
  publisher    = {Elsevier},
  title        = {{Large neutral amino acid levels tune perinatal neuronal excitability and survival}},
  doi          = {10.1016/j.cell.2023.02.037},
  volume       = {186},
  year         = {2023},
}

@article{11160,
  abstract     = {Mutations in the chromodomain helicase DNA-binding 8 (CHD8) gene are a frequent cause of autism spectrum disorder (ASD). While its phenotypic spectrum often encompasses macrocephaly, implicating cortical abnormalities, how CHD8 haploinsufficiency affects neurodevelopmental is unclear. Here, employing human cerebral organoids, we find that CHD8 haploinsufficiency disrupted neurodevelopmental trajectories with an accelerated and delayed generation of, respectively, inhibitory and excitatory neurons that yields, at days 60 and 120, symmetrically opposite expansions in their proportions. This imbalance is consistent with an enlargement of cerebral organoids as an in vitro correlate of patients’ macrocephaly. Through an isogenic design of patient-specific mutations and mosaic organoids, we define genotype-phenotype relationships and uncover their cell-autonomous nature. Our results define cell-type-specific CHD8-dependent molecular defects related to an abnormal program of proliferation and alternative splicing. By identifying cell-type-specific effects of CHD8 mutations, our study uncovers reproducible developmental alterations that may be employed for neurodevelopmental disease modeling.},
  author       = {Villa, Carlo Emanuele and Cheroni, Cristina and Dotter, Christoph and López-Tóbon, Alejandro and Oliveira, Bárbara and Sacco, Roberto and Yahya, Aysan Çerağ and Morandell, Jasmin and Gabriele, Michele and Tavakoli, Mojtaba and Lyudchik, Julia and Sommer, Christoph M and Gabitto, Mariano and Danzl, Johann G and Testa, Giuseppe and Novarino, Gaia},
  issn         = {2211-1247},
  journal      = {Cell Reports},
  keywords     = {General Biochemistry, Genetics and Molecular Biology},
  number       = {1},
  publisher    = {Elsevier},
  title        = {{CHD8 haploinsufficiency links autism to transient alterations in excitatory and inhibitory trajectories}},
  doi          = {10.1016/j.celrep.2022.110615},
  volume       = {39},
  year         = {2022},
}

@phdthesis{12364,
  abstract     = {Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders characterized by behavioral symptoms such as problems in social communication and interaction, as
well as repetitive, restricted behaviors and interests. These disorders show a high degree
of heritability and hundreds of risk genes have been identifed using high throughput
sequencing technologies. This genetic heterogeneity has hampered eforts in understanding
the pathogenesis of ASD but at the same time given rise to the concept of convergent
mechanisms. Previous studies have identifed that risk genes for ASD broadly converge
onto specifc functional categories with transcriptional regulation being one of the biggest
groups. In this thesis, I focus on this subgroup of genes and investigate the gene regulatory
consequences of some of them in the context of neurodevelopment.
First, we showed that mutations in the ASD and intellectual disability risk gene Setd5 lead
to perturbations of gene regulatory programs in early cell fate specifcation. In addition,
adult animals display abnormal learning behavior which is mirrored at the transcriptional
level by altered activity dependent regulation of postsynaptic gene expression. Lastly,
we link the regulatory function of Setd5 to its interaction with the Paf1 and the NCoR
complex.
Second, by modeling the heterozygous loss of the top ASD gene CHD8 in human cerebral
organoids we demonstrate profound changes in the developmental trajectories of both
inhibitory and excitatory neurons using single cell RNA-sequencing. While the former
were generated earlier in CHD8+/- organoids, the generation of the latter was shifted to
later times in favor of a prolonged progenitor expansion phase and ultimately increased
organoid size.
Finally, by modeling heterozygous mutations for four ASD associated chromatin modifers,
ASH1L, KDM6B, KMT5B, and SETD5 in human cortical spheroids we show evidence of
regulatory convergence across three of those genes. We observe a shift from dorsal cortical
excitatory neuron fates towards partially ventralized cell types resembling cells from the
lateral ganglionic eminence. As this project is still ongoing at the time of writing, future
experiments will aim at elucidating the regulatory mechanisms underlying this shift with
the aim of linking these three ASD risk genes through biological convergence.},
  author       = {Dotter, Christoph},
  issn         = {2663-337X},
  pages        = {152},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Transcriptional consequences of mutations in genes associated with Autism Spectrum Disorder}},
  doi          = {10.15479/at:ista:12094},
  year         = {2022},
}

@article{9429,
  abstract     = {De novo loss of function mutations in the ubiquitin ligase-encoding gene Cullin3 lead to autism spectrum disorder (ASD). In mouse, constitutive haploinsufficiency leads to motor coordination deficits as well as ASD-relevant social and cognitive impairments. However, induction of Cul3 haploinsufficiency later in life does not lead to ASD-relevant behaviors, pointing to an important role of Cul3 during a critical developmental window. Here we show that Cul3 is essential to regulate neuronal migration and, therefore, constitutive Cul3 heterozygous mutant mice display cortical lamination abnormalities. At the molecular level, we found that Cul3 controls neuronal migration by tightly regulating the amount of Plastin3 (Pls3), a previously unrecognized player of neural migration. Furthermore, we found that Pls3 cell-autonomously regulates cell migration by regulating actin cytoskeleton organization, and its levels are inversely proportional to neural migration speed. Finally, we provide evidence that cellular phenotypes associated with autism-linked gene haploinsufficiency can be rescued by transcriptional activation of the intact allele in vitro, offering a proof of concept for a potential therapeutic approach for ASDs.},
  author       = {Morandell, Jasmin and Schwarz, Lena A and Basilico, Bernadette and Tasciyan, Saren and Dimchev, Georgi A and Nicolas, Armel and Sommer, Christoph M and Kreuzinger, Caroline and Dotter, Christoph and Knaus, Lisa and Dobler, Zoe and Cacci, Emanuele and Schur, Florian KM and Danzl, Johann G and Novarino, Gaia},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  keywords     = {General Biochemistry, Genetics and Molecular Biology},
  number       = {1},
  publisher    = {Springer Nature},
  title        = {{Cul3 regulates cytoskeleton protein homeostasis and cell migration during a critical window of brain development}},
  doi          = {10.1038/s41467-021-23123-x},
  volume       = {12},
  year         = {2021},
}

@article{10281,
  abstract     = {Mutations affecting mTOR or RAS signaling underlie defined syndromes (the so-called mTORopathies and RASopathies) with high risk for Autism Spectrum Disorder (ASD). These syndromes show a broad variety of somatic phenotypes including cancers, skin abnormalities, heart disease and facial dysmorphisms. Less well studied are the neuropsychiatric symptoms such as ASD. Here, we assess the relevance of these signalopathies in ASD reviewing genetic, human cell model, rodent studies and clinical trials. We conclude that signalopathies have an increased liability for ASD and that, in particular, ASD individuals with dysmorphic features and intellectual disability (ID) have a higher chance for disruptive mutations in RAS- and mTOR-related genes. Studies on rodent and human cell models confirm aberrant neuronal development as the underlying pathology. Human studies further suggest that multiple hits are necessary to induce the respective phenotypes. Recent clinical trials do only report improvements for comorbid conditions such as epilepsy or cancer but not for behavioral aspects. Animal models show that treatment during early development can rescue behavioral phenotypes. Taken together, we suggest investigating the differential roles of mTOR and RAS signaling in both human and rodent models, and to test drug treatment both during and after neuronal development in the available model systems},
  author       = {Vasic, Verica and Jones, Mattson S.O. and Haslinger, Denise and Knaus, Lisa and Schmeisser, Michael J. and Novarino, Gaia and Chiocchetti, Andreas G.},
  issn         = {2073-4425},
  journal      = {Genes},
  number       = {11},
  publisher    = {MDPI},
  title        = {{Translating the role of mtor-and ras-associated signalopathies in autism spectrum disorder: Models, mechanisms and treatment}},
  doi          = {10.3390/genes12111746},
  volume       = {12},
  year         = {2021},
}

@article{7957,
  abstract     = {Neurodevelopmental disorders (NDDs) are a class of disorders affecting brain development and function and are characterized by wide genetic and clinical variability. In this review, we discuss the multiple factors that influence the clinical presentation of NDDs, with particular attention to gene vulnerability, mutational load, and the two-hit model. Despite the complex architecture of
mutational events associated with NDDs, the various proteins involved appear to converge on common pathways, such as synaptic plasticity/function, chromatin remodelers and the mammalian target of rapamycin (mTOR) pathway. A thorough understanding of the mechanisms behind these pathways will hopefully lead to the identification of candidates that could be targeted for treatment approaches.},
  author       = {Parenti, Ilaria and Garcia Rabaneda, Luis E and Schön, Hanna and Novarino, Gaia},
  issn         = {1878108X},
  journal      = {Trends in Neurosciences},
  number       = {8},
  pages        = {608--621},
  publisher    = {Elsevier},
  title        = {{Neurodevelopmental disorders: From genetics to functional pathways}},
  doi          = {10.1016/j.tins.2020.05.004},
  volume       = {43},
  year         = {2020},
}