José González-Martínez

The atypical cyclin-dependent kinase subfamily (CDK14–18) encompasses five related proteins with unclear function, and for which individual depletion has not demonstrated sustained therapeutic relevance. We report here that CDK16 and CDK18 compensate each other and liver cancer cells are sensitive to the concomitant inactivation of both kinases, resulting in persistent defects in DNA repair and subsequent cell death. These effects are linked to a role of CDK16/18 in regulating nucleocytoplasmatic transport through phosphorylation of nuclear pore complex components, including NUP35. Genetic ablation of Cdk16 and Cdk18 in established liver tumors driven by MYC and beta-catenin oncogenes triggers DNA damage in cancer cells without affecting adjacent normal tissue, ultimately leading to tumor regression. Collectively, these findings provide a rationale for the development of CDK16–18 inhibitors—likely targeting multiple subfamily members due to their structural similarity—as a strategy against aggressive cancers, such as hepatocellular carcinoma, where effective treatment options remain limited.

Commonly expressed at developmental transitions, microRNAs operate as fine-tuners of gene expression to facilitate cell fate acquisition and lineage segregation. Nevertheless, how they might regulate the earliest developmental transitions in early mammalian embryogenesis remains obscure. Here, in a strictly in vivo approach based on genetically engineered mouse models and single-cell RNA sequencing, we identify microRNA-203 (miR-203) as a critical regulator of timely progression in preimplantation mouse embryos. Genetically engineered mouse models including a generated embryonic reporter (early embryo reporter) transgenic mouse carrying murine endogenous retrovirus-L (MERVL)–Tomato and SRY-box 2 (Sox2)–green fluorescent protein transgenes show that loss of miR-203 slows down early preimplantation development leading to the accumulation of embryos with high expression of totipotency-associated markers, including MERVL endogenous retroviral elements. A combination of single-cell transcriptional studies and epigenetic analyses identified histone acetylases including the central coactivator and histone acetyltransferase EP300 as critical miR-203 targets in the control of cell specification in early embryos. These data suggest that miR-203 carves the epigenetic rewiring required for early developmental transitions, allowing a timely and correctly paced development, at least partially by fine-tuning EP300 levels.

Brain development requires correct tissue patterning and production of appropriate cell types. Transcription factors play essential roles in these processes, regulating the expression of target genes responsible for the specific features of neuronal subtypes. Cell adhesion molecules are key components of developmental processes that control cell sorting, migration, neurite outgrowth/guidance and synaptogenesis. To date, the link between transcription factors and cell adhesion molecules has been considered unidirectional. Here, we demonstrate that ectopic expression of Dbx1 leads to spatiotemporally restricted increased expression of Pcdh8 and cell aggregation, together with changes in neuronal identity. Surprisingly, ectopic Pcdh8 expression also induces Dbx1 expression, as well as a complete reorganisation of apico-basal polarity and dorso-ventral patterning via Notch signalling. Altogether, our work therefore points to cell adhesion molecules as unexpected, yet important, players in the regulation of cell identity and, in particular, Pcdh8 through its bidirectional interaction with the Dbx1 transcription factor.

Advancing next-generation bioelectronic interfaces requires devices that are soft, miniaturized, and seamlessly integrated with biological tissues. However, conventional fabrication methods, primarily based on UV photolithography, struggle to meet these needs, relying on hazardous chemicals, labor-intensive processes, and planar, layer-by-layer construction. To overcome these limits, we introduce dynamically autofocused 3D pulsed laser micromachining (d-3DPLM) using a nanosecond pulsed near-infrared laser. This approach enables rapid, cost-effective structuring of diverse materials, including thin films, metal foils, and bulk metal blocks, supporting monolithic, multilayer bioelectronics with complex 3D architectures such as microneedles and deployable elements. d-3DPLM achieves high-resolution ablation and patterning for conformable and functional device geometries. Demonstrated applications include electro-haptic patches, in vitro multielectrode diagnostic arrays, and wireless contact lenses for red light therapy. By broadening the design and manufacturing landscape for bioelectronic systems, this versatile method paves the way for improved performance, unique functionality, and enhanced integration with living tissue.

The human cerebellum has undergone significant evolutionary expansion compared to other species, contributing to both motor and cognitive skills. However, the mechanisms underlying this process remain largely unknown as interrogating human cerebellar development alongside other species has to date been unfeasible. To address this, we developed a minimally guided cerebellar organoid protocol that combines unguided neural induction with precise temporal calibration of posteriorizing morphogens. This approach effectively overrides default telencephalic fate in cerebral organoids and induces stable cerebellar identities. Cerebellar organoids derived from both human and mouse ESCs exhibit species-specific size differences at comparable developmental stages and show robust induction of cerebellar master regulators and progenitor cell types. This model provides a powerful tool for investigating the mechanisms underlying cerebellar development in the context of both evolution and disease.

Commonly expressed at developmental transitions, microRNAs operate as fine tuners of gene expression to facilitate cell fate acquisition and lineage segregation. Nevertheless, how they might regulate the earliest developmental transitions in early mammalian embryogenesis remains obscure. Here, in a strictly in vivo approach based on novel genetically-engineered mouse models and single-cell RNA sequencing, we identify miR-203 as a critical regulator of timing and cell fate restriction within the totipotency to pluripotency transition in mouse embryos. Genetically engineered mouse models show that loss of miR-203 slows down developmental timing during preimplantation leading to the accumulation of embryos with high expression of totipotency-associated markers, including MERVL endogenous retroviral elements. A new embryonic reporter (eE-Reporter) transgenic mouse carrying MERVL-Tomato and Sox2-GFP transgenes showed that lack of miR-203 leads to sustained expression of MERVL and reduced Sox2 expression in preimplantation developmental stages. A combination of single-cell transcriptional studies and epigenetic analyses identified the central coactivator and histone acetyltransferase P300 as a major miR-203 target at the totipotency to pluripotency transition in vivo. By fine tuning P300 levels, miR-203 carves the epigenetic rewiring process needed for this developmental transition, allowing a timely and correctly paced development.

SUMMARY: Brain development requires correct tissue patterning and production of appropriate cell types. Transcription factors (TFs) play essential roles in these processes, regulating the expression of target genes responsible for neuronal subtypes specific features. Cell adhesion molecules are key components of developmental processes that control cell sorting, migration, neurite outgrowth/guidance and synaptogenesis. To date, the link between TFs and cell adhesion molecules is considered to be unidirectional. Here, we demonstrate that ectopic expression of Dbx1 leads to spatio-temporally restricted increased expression of Pcdh8 and cell aggregation, together with changes in neuronal identity. Surprisingly, Pcdh8 overexpression also induces Dbx1 expression as well as a complete reorganisation of apico-basal polarity and dorso-ventral patterning via Notch signalling. Altogether, our work therefore points to cell adhesion molecules as unexpected, yet important, players in the regulation of cell identity and, in particular, Pcdh8 through its bidirectional interaction with the Dbx1 transcription factor.

The AKT-mTOR pathway is a central regulator of cell growth and metabolism. Upon sustained mTOR activity, AKT activity is attenuated by a feedback loop that restrains upstream signaling. However, how cells control the signals that limit AKT activity is not fully understood. Here, we show that MASTL/Greatwall, a cell cycle kinase that supports mitosis by phosphorylating the PP2A/B55 inhibitors ENSA/ARPP19, inhibits PI3K-AKT activity by sustaining mTORC1- and S6K1-dependent phosphorylation of IRS1 and GRB10. Genetic depletion of MASTL results in an inefficient feedback loop and AKT hyperactivity. These defects are rescued by the expression of phosphomimetic ENSA/ARPP19 or inhibition of PP2A/B55 phosphatases. MASTL is directly phosphorylated by mTORC1, thereby limiting the PP2A/B55-dependent dephosphorylation of IRS1 and GRB10 downstream of mTORC1. Downregulation of MASTL results in increased glucose uptake in vitro and increased glucose tolerance in adult mice, suggesting the relevance of the MASTL-PP2A/B55 kinase-phosphatase module in controlling AKT and maintaining metabolic homeostasis.

Alteration of centrosome function and dynamics results in major defects during chromosome segregation and is associated with primary autosomal microcephaly (MCPH). Despite the knowledge accumulated in the last few years, why some centrosomal defects specifically affect neural progenitors is not clear. We describe here that the centrosomal kinase PLK1 controls centrosome asymmetry and cell fate in neural progenitors during development. Gain- or loss-of-function mutations in Plk1, as well as deficiencies in the MCPH genes Cdk5rap2 (MCPH3) and Cep135 (MCPH8), lead to abnormal asymmetry in the centrosomes carrying the mother and daughter centriole in neural progenitors. However, whereas loss of MCPH proteins leads to increased centrosome asymmetry and microcephaly, deficient PLK1 activity results in reduced asymmetry and increased expansion of neural progenitors and cortical growth during mid-gestation. The combination of PLK1 and MCPH mutations results in increased microcephaly accompanied by more aggressive centrosomal and mitotic abnormalities. In addition to highlighting the delicate balance in the level and activity of centrosomal regulators, these data suggest that human PLK1, which maps to 16p12.1, may contribute to the neurodevelopmental defects associated with 16p11.2–p12.2 microdeletions and microduplications in children with developmental delay and dysmorphic features.