@unpublished{21290, abstract = {Gene duplication underlies evolutionary innovation, yet many paralogues remain highly similar, raising questions about their functional divergence and physiological relevance. The spliceosomal Sm core protein SNRPB and its mammalian-specific paralogue SNRPN share over 90% sequence identity, but their distinct expression patterns - SNRPB being ubiquitous and SNRPN confined to the brain - suggest specialized functions. Why mammals have two different spliceosomes has remained obscure. Here, we generated isogenic human cell lines expressing ectopically either SNRPB or SNRPN exclusively and found that SNRPN stabilizes transcripts involved in energy metabolism and mitochondrial function, leading to increased mitochondrial abundance and oxygen consumption. Despite similar spliceosomal interactomes, SNRPN more strongly associates with the PRMT5 methylosome complex and exhibits dynamic arginine methylation in its C-terminal region that is sensitive to translation inhibition and amino acid availability. The SNRPN-dependent transcriptome responds to translation inhibition by stabilizing long, intron-rich genes involved in amino acid and energy metabolism. Our findings reveal a nutrient-sensitive, methylation-dependent mechanism that differentiates the two paralogues. This suggests that SNRPN functions as a metabolic-specialized spliceosomal subunit thereby providing tissue-specific adaptation of RNA processing in mammals.}, author = {Polat Haas, Feyza and Villalba Requena, Ana and Rusina, Polina and Gopalan, Anusha and Fritz, Hector and Akhmetkaliyev, Azamat and Ruehle, Frank and Einsiedel, Anna and Szczepinska, Anna and Kielisch, Fridolin and Chen, Jia-Xuan and Nguyen, Susanne and Schmidlin, Thierry and Hippenmeyer, Simon and Bailicata, M. Felicia and Keller Valsecchi, Claudia Isabelle}, booktitle = {bioRxiv}, title = {{The splicing paralogues SNRPB and SNRPN control differential metabolic states.}}, doi = {10.64898/2026.02.11.705284}, year = {2026}, } @unpublished{21962, abstract = {The generation of faithful cell-type diversity and correct projection neuron numbers is essential for cerebral cortex development. Corticogenesis is however susceptible to genetic interference of critical signaling pathways, including mutations in Mtor/Rptor that lead to microcephaly. How the loss of Rptor/mTORC1 function affects cortical developmental programs, at single cell level, is still unknown. Here, we utilized Mosaic Analysis with Double Markers (MADM) technology to probe Rptor gene function upon sparse single cell- or global tissue-wide ablation. We found that tissue-wide effects drive the etiology of cortical microcephaly upon loss of Rptor, rather than deficits in projection neuron genesis. Conversely, Rptor function is cell-autonomously required for postnatal projection neuron survival in a highly cell-type-specific manner. Collectively, our results suggest that the fine balance of precise cell-type-specific cell-autonomous Rptor/mTORC1 function in concert with non-cell-autonomous tissue-wide effects is essential for the development of a properly-sized cerebral cortex with accurate projection neuron diversity.}, author = {Villalba Requena, Ana and Beattie, Robert J and Pauler, Florian and Streicher, Carmen and Miranda, Osvaldo and Krausgruber, Thomas and Senekowitsch, Martin and Farlik, Matthias and Bock, Christoph and Rülicke, Thomas and Hippenmeyer, Simon}, booktitle = {bioRxiv}, title = {{Mtor/Rptor function globally prevents cortical microcephaly and cell-autonomously promotes postnatal neuron survival in cell type specific manner}}, doi = {10.64898/2026.05.01.722172}, year = {2026}, } @unpublished{21963, abstract = {The cerebral cortex consists of immense numbers of neuronal and glial cell-types derived from radial glial progenitor (RGP) cells. How RGPs generate appropriate quantities of distinct cortical cell-types to safeguard a brain of correct size, is not well understood. However, genetic aberration in human, including mutations in PTEN, lead to cortical malformation such as macrocephaly, albeit with unknown etiology. Here we utilized Mosaic Analysis with Double Markers (MADM)-based clonal analysis and single cell phenotyping to decipher the role of Pten in neurogenic and gliogenic RGP lineage progression during cortical ontogeny. While neurogenic RGP lineage progression and projection neuron production was moderately altered in the absence of Pten, cortical astrocyte production was drastically increased. Through genetic epistasis experiments we show that the loss of Pten uncouples astrocyte generation from essential growth factor signaling hubs, funneling into MAPK. Collectively, our results suggest that Pten regulates RGP lineage progression with distinct sequential functions in cortical projection neurogenesis and astrocyte production to ensure the emergence of a correctly-sized cerebral cortex.}, author = {Miranda, Osvaldo and Contreras, Ximena and Pauler, Florian and Davaatseren, Amarbayasgalan and Amberg, Nicole and Streicher, Carmen and Villalba Requena, Ana and Heger, Anna-Magdalena and Marie, Corentine and Hassan, Bassem A. and Rülicke, Thomas and Hippenmeyer, Simon}, booktitle = {bioRxiv}, title = {{Pten orchestrates neurogenic radial glia lineage progression and tunes neocortical astrocyte production}}, doi = {10.64898/2026.05.01.722191}, year = {2026}, } @article{22714, abstract = {Radial glial progenitors (RGPs) generate all projection neurons (PNs) in the cerebral cortex through incompletely understood processes. We combined Mosaic Analysis with Double Markers at embryonic stages (E)12.5 and E13.5 with early postnatal callosal tracing to dissect RGP lineage progression. We find that multipotent RGPs generate all extra-telencephalic (ET) and intra-telencephalic (IT) PNs via parallel sublineages that emerge simultaneously at neurogenesis onset. ET-PN production progresses exclusively via small, self-consuming lineages; IT-PN lineages feature RGPs generating large translaminar outputs. The early emergence of IT-PN–fated RGPs, coinciding with a switch to direct neurogenesis, contributes to the stereotyped population-level progression of the multipotent lineage. We also identify POU3F transcription factors as candidate regulators of IT-PN fate via noncanonical mitotic chromatin binding. The results support a model whereby IT- and ET-PNs arise from an early bifurcation and parallel specification within the multipotent RGP lineage.}, author = {Varela Martínez, Irene and Villalba Requena, Ana and García-Marqués, Jorge and Aguilera, Alfonso and Castro, Diogo S. and Hippenmeyer, Simon and Nieto, Marta}, issn = {2375-2548}, journal = {Science Advances}, number = {32}, pages = {eadw5487}, publisher = {AAAS}, title = {{Early fate diversification of radial glial progenitors during corticogenesis}}, doi = {10.1126/sciadv.adw5487}, volume = {12}, year = {2026}, } @article{19718, abstract = {The cerebral cortex is arguably the most complex organ in humans. The cortical architecture is characterized by a remarkable diversity of neuronal and glial cell types that make up its neuronal circuits. Following a precise temporally ordered program, radial glia progenitor (RGP) cells generate all cortical excitatory projection neurons and glial cell-types. Cortical excitatory projection neurons are produced either directly or via intermediate progenitors, through indirect neurogenesis. How the extensive cortical cell-type diversity is generated during cortex development remains, however, a fundamental open question. How do RGPs quantitatively and qualitatively generate all the neocortical neurons? How does direct and indirect neurogenesis contribute to the establishment of neuronal and lineage heterogeneity? Whether RGPs represent a homogeneous and/or multipotent progenitor population, or if RGPs consist of heterogeneous groups is currently also not known. In this review, we will summarize the latest findings that contributed to a deeper insight into the above key questions.}, author = {Pipicelli, Fabrizia and Villalba Requena, Ana and Hippenmeyer, Simon}, issn = {0959-4388}, journal = {Current Opinion in Neurobiology}, publisher = {Elsevier}, title = {{How radial glia progenitor lineages generate cell-type diversity in the developing cerebral cortex}}, doi = {10.1016/j.conb.2025.103046}, volume = {93}, year = {2025}, } @unpublished{19717, abstract = {Radial glial progenitors (RGPs) generate all projection neurons (PNs) in the cerebral cortex through incompletely understood processes. Herein, we combine Mosaic Analysis with Double Markers (MADM)-based clonal analysis at embryonic days 12.5 and 13.5 with early postnatal callosal tracing to reveal a lineage progression that challenges the inside-outside model of cortical development and the conventional view of an invariable sequence of asymmetric neurogenic divisions. Our data demonstrate that early multipotent RGPs generate all extra-telencephalic (ET) and intra-telencephalic (IT) PNs across all layers through parallel sublineages and the random specification, during the earliest neurogenic divisions, of fate-restricted daughter RGPs. While the neuronal production of the parental multipotent RGPs consists of small ET-PN or IT-PN outputs, fate-restricted RGPs produce larger translaminar outputs spanning deep and upper layers of only IT-PNs, the predominant mammalian PN subtype. We further show that the emergence of IT-PN fate-restricted RGPs also leads to quantitatively and temporally stereotyped neurogenesis population-wise.}, author = {Varela-Martínez, I and Villalba Requena, Ana and Garcia-Marqués, J. and Hippenmeyer, Simon and Nieto, M.}, booktitle = {bioRxiv}, title = {{Early emergence of projection-subtype fate-restricted radial glial progenitors orchestrates neocortical neurogenesis}}, doi = {10.1101/2025.05.07.652665}, year = {2025}, } @article{12542, abstract = {In this issue of Neuron, Espinosa-Medina et al.1 present the TEMPO (Temporal Encoding and Manipulation in a Predefined Order) system, which enables the marking and genetic manipulation of sequentially generated cell lineages in vertebrate species in vivo.}, author = {Villalba Requena, Ana and Hippenmeyer, Simon}, issn = {1097-4199}, journal = {Neuron}, number = {3}, pages = {291--293}, publisher = {Elsevier}, title = {{Going back in time with TEMPO}}, doi = {10.1016/j.neuron.2023.01.006}, volume = {111}, year = {2023}, } @inbook{14757, abstract = {The cerebral cortex is comprised of a vast cell-type diversity sequentially generated by cortical progenitor cells. Faithful progenitor lineage progression requires the tight orchestration of distinct molecular and cellular mechanisms regulating proper progenitor proliferation behavior and differentiation. Correct execution of developmental programs involves a complex interplay of cell intrinsic and tissue-wide mechanisms. Many studies over the past decades have been able to determine a plethora of genes critically involved in cortical development. However, only a few made use of genetic paradigms with sparse and global gene deletion to probe cell-autonomous vs. tissue-wide contribution. In this chapter, we will elaborate on the importance of dissecting the cell-autonomous and tissue-wide mechanisms to gain a precise understanding of gene function during radial glial progenitor lineage progression.}, author = {Villalba Requena, Ana and Amberg, Nicole and Hippenmeyer, Simon}, booktitle = {Neocortical Neurogenesis in Development and Evolution}, editor = {Huttner, Wieland}, pages = {169--191}, publisher = {Wiley}, title = {{Interplay of Cell‐autonomous Gene Function and Tissue‐wide Mechanisms Regulating Radial Glial Progenitor Lineage Progression}}, doi = {10.1002/9781119860914.ch10}, year = {2023}, }