Curriculum Vitae

Publications

2022

BAF (mSWI/SNF) complex regulates mediolateral cortical patterning in the developing forebrain.
Huong Nguyen, Godwin Sokpor, Arpan Parichha, Linh Pham, Nidhi Saikhedkar, Yuanbin Xie, Pauline Antonie Ulmke, Joachim Rosenbusch, Mehdi Pirouz, Rüdiger Behr, Anastassia Stoykova, Beate Brand-Saberi, Huu Phuc Nguyen, Jochen F. Staiger, Shubha Tole and Tran Tuoc.
Front. Cell Dev. Biol. 10:1011109. doi: 10.3389/fcell.2022.1011109, 2022.
abstract

Early forebrain patterning entails the correct regional designation of theneuroepithelium, and appropriate specification, generation, and distributionof neural cells during brain development. Specific signaling and transcriptionfactors are known to tightly regulate patterning of the dorsal telencephalon toafford proper structural/functional cortical arealization and morphogenesis.Nevertheless, whether and how changes of the chromatin structure link to thetranscriptional program(s) that control cortical patterning remains elusive. Here,we report that the BAF chromatin remodeling complex regulates thespatiotemporal patterning of the mouse dorsal telencephalon. To determinewhether and how the BAF complex regulates cortical patterning, weconditionally deleted the BAF complex scaffolding subunits BAF155 andBAF170 in the mouse dorsal telencephalic neuroepithelium. Morphologicaland cellular changes in the BAF mutant forebrain were examined usingimmunohistochemistry and in situ hybridization. RNA sequencing, Coimmunoprecipitation,and mass spectrometry were used to investigate themolecular basis of BAF complex involvement in forebrain patterning. We foundthat conditional ablation of BAF complex in the dorsal telencephalonneuroepithelium caused expansion of the cortical hem and medial cortexbeyond their developmental boundaries. Consequently, the hippocampalprimordium is not specified, the mediolateral cortical patterning iscompromised, and the cortical identity is disturbed in the absence of BAFcomplex. The BAF complex was found to interact with the cortical hemsuppressor LHX2. The BAF complex suppresses cortical hem fate to permitproper forebrain patterning. We provide evidence that BAF complex modulatesmediolateral cortical patterning possibly by interacting with the transcriptionfactor LHX2 to drive the LHX2-dependent transcriptional program essential fordorsal telencephalon patterning. Our data suggest a putative mechanisticsynergy between BAF chromatin remodeling complex and LHX2 inregulating forebrain patterning and ontogeny.

2021

H3 acetylation selectively promotes basal progenitor proliferation and neocortex expansion.
Cemil Kerimoglu, Linh Pham, Anton B. Tonchev, M. Sadman Sakib, Yuanbin Xie, Godwin Sokpor, Pauline Antonie Ulmke, Lalit Kaurani, Eman Abbas, Huong Nguyen, Joachim Rosenbusch, Alexandra Michurina, Vincenzo Capece, Meglena Angelova, Nenad Maricic, Beate Brand-Saberi, Miriam Esgleas, Mareike Albert, Radoslav Minkov, Emil Kovachev, Ulrike Teichmann, Rho H. Seong, Wieland B. Huttner, Huu Phuc Nguyen, Anastassia Stoykova, Jochen F. Staiger, Andre Fischer, Tran Tuoc.
Science Advances 2021; 7 : eabc6792, 2021.
abstract link

Increase in the size of human neocortex―acquired in evolution―accounts for the unique cognitive capacity ofhumans. This expansion reflects the evolutionarily enhanced proliferative ability of basal progenitors (BPs), includingthe basal radial glia and basal intermediate progenitors (bIPs) in mammalian cortex, which may have been acquiredthrough epigenetic alterations in BPs. However, how the epigenome in BPs differs across species is not known.Here, we report that histone H3 acetylation is a key epigenetic regulation in bIP amplification and cortical expansion.Through epigenetic profiling of sorted bIPs, we show that histone H3 lysine 9 acetylation (H3K9ac) is low inmurine bIPs and high in human bIPs. Elevated H3K9ac preferentially increases bIP proliferation, increasing the sizeand folding of the normally smooth mouse neocortex. H3K9ac drives bIP amplification by increasing expressionof the evolutionarily regulated gene, Trnp1, in developing cortex. Our findings demonstrate a previously unknownmechanism that controls cortical architecture.

Molecular Profiling Reveals Involvement of ESCO2 in Intermediate Progenitor Cell Maintenance in the Developing Mouse Cortex.
Pauline Antonie Ulmke, M Sadman Sakib, Peter Ditte, Godwin Sokpor, Cemil Kerimoglu, Linh Pham, Yuanbin Xie, Xiaoyi Mao, Joachim Rosenbusch, Ulrike Teichmann, Huu Phuc Nguyen, Andre Fischer, Gregor Eichele, Jochen F Staiger, Tran Tuoc.
Stem Cell Reports 2021 Apr 13;16(4):968-984, 2021.
abstract link

Post-transcriptional regulation by the exosome complex is required for cell survival and forebrain development via repression of P53 signaling.
Pauline Antonie Ulmke, Yuanbin Xie, Godwin Sokpor, Linh Pham, Orr Shomroni, Tea Berulava, Joachim Rosenbusch, Uttiya Basu, Andre Fischer, Huu Phuc Nguyen, Jochen F. Staiger, Tran Tuoc.
Development 2021 148: dev188276 doi: 10.1242/dev.188276, 2021.
abstract link

Fine-tuned gene expression is crucial for neurodevelopment. The gene expression program is tightly controlled at different levels, including RNA decay. N6-methyladenosine (m6A) methylation-mediated degradation of RNA is essential for brain development. However, m6A methylation impacts not only RNA stability, but also other RNA metabolism processes. How RNA decay contributes to brain development is largely unknown. Here, we show that Exosc10, a RNA exonuclease subunit of the RNA exosome complex, is indispensable for forebrain development. We report that cortical cells undergo overt apoptosis, culminating in cortical agenesis upon conditional deletion of Exosc10 in mouse cortex. Mechanistically, Exosc10 directly binds and degrades transcripts of the P53 signaling-related genes, such as Aen and Bbc3. Overall, our findings suggest a crucial role for Exosc10 in suppressing the P53 pathway, in which the rapid turnover of the apoptosis effectors Aen and Bbc3 mRNAs is essential for cell survival and normal cortical histogenesis.

2019

Structural brain anomalies in patients with FOXG1 syndrome and in Foxg1+/− mice.
Pringsheim M,, Mitter D, Schröder S, Warthemann R, Plümacher K, Kluger G, Baethmann M, Bast T, Braun S, Büttel HM, Conover E, Courage C, Datta AN, Eger A, Grebe TA, Hasse‐Wittmer A, Heruth M, Höft K, Kaindl AM, Karch S, Kautzky T, Korenke GC, Kruse B, Lutz RE, Omran H, Patzer S, Philippi H, Ramsey K, Rating T, Rieß A, Schimmel M, Westman R, Zech FM, Zirn B, Ulmke PA, Sokpor G, Tuoc T, Leha A, Staudt M, Brockmann K.
Ann Clin Transl Neurol. https://doi.org/10.1002/acn3.735, 2019.
abstract link

Objective
FOXG1 syndrome is a rare neurodevelopmental disorder associated with heterozygous FOXG1 variants or chromosomal microaberrations in 14q12. The study aimed at assessing the scope of structural cerebral anomalies revealed by neuroimaging to delineate the genotype and neuroimaging phenotype associations.

Methods
We compiled 34 patients with a heterozygous (likely) pathogenic FOXG1 variant. Qualitative assessment of cerebral anomalies was performed by standardized re‐analysis of all 34 MRI data sets. Statistical analysis of genetic, clinical and neuroimaging data were performed. We quantified clinical and neuroimaging phenotypes using severity scores. Telencephalic phenotypes of adult Foxg1+/− mice were examined using immunohistological stainings followed by quantitative evaluation of structural anomalies.

Results
Characteristic neuroimaging features included corpus callosum anomalies (82%), thickening of the fornix (74%), simplified gyral pattern (56%), enlargement of inner CSF spaces (44%), hypoplasia of basal ganglia (38%), and hypoplasia of frontal lobes (29%). We observed a marked, filiform thinning of the rostrum as recurrent highly typical pattern of corpus callosum anomaly in combination with distinct thickening of the fornix as a characteristic feature. Thickening of the fornices was not reported previously in FOXG1 syndrome. Simplified gyral pattern occurred significantly more frequently in patients with early truncating variants. Higher clinical severity scores were significantly associated with higher neuroimaging severity scores. Modeling of Foxg1 heterozygosity in mouse brain recapitulated the associated abnormal cerebral morphology phenotypes, including the striking enlargement of the fornix.

Interpretation
Combination of specific corpus callosum anomalies with simplified gyral pattern and hyperplasia of the fornices is highly characteristic for FOXG1 syndrome.

2018

Chromatin remodeling BAF155 subunit regulates the genesis of basal progenitors in developing cortex .
Narayanan R, Pham L, Kerimoglu C, Watanabe T, Hernandez RC, Sokpor G, Ulmke PA, Kiszka KA, Tonchev AB, Rosenbusch J, Seong RH, Teichmann U, Frahm J, Fischer F, Bonn S, Stoykova A, Staiger JF, Tuoc T.
iScience (Cell Press), DOI: https://doi.org/10.1016/j.isci.2018.05.014, 2018.
abstract link

The abundance of basal progenitors (BPs) - basal radial glia progenitors (bRGs) and basal intermediate progenitors (bIPs), in primate brain has been correlated to the high degree of cortical folding. Here we examined the role of BAF155, a subunit of the chromatin remodeling BAF complex, in generation of cortical progenitor heterogeneity. The conditional deletion of BAF155 led to diminished bIP pool and increased number of bRGs, due to delamination of apical RGs. We found that BAF155 is required for normal activity of neurogenic transcription factor PAX6, thus controlling expression of genes that are involved in bIP specification, cell-cell interaction and establishment of adherens junction. In PAX6-dependent manner, BAF155 regulates the expression of the CDC42 effector protein CEP4, thereby controlling progenitor delamination. Furthermore, BAF155-dependent chromatin remodeling seems to exert a specific role in the genesis of BPs through regulation of human RG-specific genes (such as Foxn4) that possibly acquired evolutionary significance.

2012

Unique functional properties of somatostatin-expressing GABAergic neurons in mouse barrel cortex.
Gentet LJ, Kremer Y, Taniguchi H, Huang ZJ, Staiger J, Petersen CCH.
Nat Neurosci 15:607-612, 2012.
abstract link

Neocortical GABAergic neurons have diverse molecular, structural and electrophysiological features, but the functional correlates of this diversity are largely unknown. We found unique membrane potential dynamics of somatostatin-expressing (SOM) neurons in layer 2/3 of the primary somatosensory barrel cortex of awake behaving mice. SOM neurons were spontaneously active during periods of quiet wakefulness. However, SOM neurons hyperpolarized and reduced action potential firing in response to both passive and active whisker sensing, in contrast with all other recorded types of nearby neurons, which were excited by sensory input. Optogenetic inhibition of SOM neurons increased burst firing in nearby excitatory neurons. We hypothesize that the spontaneous activity of SOM neurons during quiet wakefulness provides a tonic inhibition to the distal dendrites of excitatory pyramidal neurons. Conversely, the inhibition of SOM cells during active cortical processing likely enhances distal dendritic excitability, which may be important for top-down computations and sensorimotor integration.