Cranial Suture Regeneration Mitigates Skull and Neurocognitive Defects in Craniosynostosis.

Craniosynostosis results from premature fusion of the cranial suture(s), which contain mesenchymal stem cells (MSCs) that are crucial for calvarial expansion in coordination with brain growth. Infants with craniosynostosis have skull dysmorphology, increased intracranial pressure, and complications such as neurocognitive impairment that compromise quality of life. Animal models recapitulating these phenotypes are lacking, hampering development of urgently needed innovative therapies. Here, we show that Twist1+/- mice with craniosynostosis have increased intracranial pressure and neurocognitive behavioral abnormalities, recapitulating features of human Saethre-Chotzen syndrome. Using a biodegradable material combined with MSCs, we successfully regenerated a functional cranial suture that corrects skull deformity, normalizes intracranial pressure, and rescues neurocognitive behavior deficits. The regenerated suture creates a niche into which endogenous MSCs migrated, sustaining calvarial bone homeostasis and repair. MSC-based cranial suture regeneration offers a paradigm shift in treatment to reverse skull and neurocognitive abnormalities in this devastating disease.

Cerebral organoid and mouse models reveal a RAB39b-PI3K-mTOR pathway-dependent dysregulation of cortical development leading to macrocephaly/autism phenotypes.

Dysregulation of early neurodevelopment is implicated in macrocephaly/autism disorders. However, the mechanism underlying this dysregulation, particularly in human cells, remains poorly understood. Mutations in the small GTPase gene RAB39b are associated with X-linked macrocephaly, autism spectrum disorder (ASD), and intellectual disability. The in vivo roles of RAB39b in the brain remain unknown. We generated Rab39b knockout (KO) mice and found that they exhibited cortical neurogenesis impairment, macrocephaly, and hallmark ASD behaviors, which resembled patient phenotypes. We also produced mutant human cerebral organoids that were substantially enlarged due to the overproliferation and impaired differentiation of neural progenitor cells (NPCs), which resemble neurodevelopmental deficits in KO mice. Mechanistic studies reveal that RAB39b interacts with PI3K components and its deletion promotes PI3K-AKT-mTOR signaling in NPCs of mouse cortex and cerebral organoids. The mTOR activity is robustly enhanced in mutant outer radial glia cells (oRGs), a subtype of NPCs barely detectable in rodents but abundant in human brains. Inhibition of AKT signaling rescued enlarged organoid sizes and NPC overproliferation caused by RAB39b mutations. Therefore, RAB39b mutation promotes PI3K-AKT-mTOR activity and alters cortical neurogenesis, leading to macrocephaly and autistic-like behaviors. Our studies provide new insights into neurodevelopmental dysregulation and common pathways associated with ASD across species.

Sensory nerve regulates progenitor cells via FGF-SHH axis in tooth root morphogenesis.

Nerves play important roles in organ development and tissue homeostasis. Stem/progenitor cells differentiate into different cell lineages responsible for building the craniofacial organs. The mechanism by which nerves regulate stem/progenitor cell behavior in organ morphogenesis has not yet been comprehensively explored. Here, we use tooth root development in mouse as a model to investigate how sensory nerves regulate organogenesis. We show that sensory nerve fibers are enriched in the dental papilla at the initiation of tooth root development. Through single cell RNA-sequencing analysis of the trigeminal ganglion and developing molar, we reveal several signaling pathways that connect the sensory nerve with the developing molar, of which FGF signaling appears to be one of the important regulators. Fgfr2 is expressed in the progenitor cells during tooth root development. Loss of FGF signaling leads to shortened roots with compromised proliferation and differentiation of progenitor cells. Furthermore, Hh signaling is impaired in Gli1-CreER;Fgfr2fl/fl mice. Modulation of Hh signaling rescues the tooth root defects in these mice. Collectively, our findings elucidate the nerve-progenitor crosstalk and reveal the molecular mechanism of the FGF-SHH signaling cascade during tooth root morphogenesis.

Canonical Wnt signaling regulates soft palate development by mediating ciliary homeostasis.

Craniofacial morphogenesis requires complex interactions involving different tissues, signaling pathways, secreted factors and organelles. The details of these interactions remain elusive. In this study, we have analyzed the molecular mechanisms and homeostatic cellular activities governing soft palate development to improve regenerative strategies for individuals with cleft palate. We have identified canonical Wnt signaling as a key signaling pathway primarily active in cranial neural crest (CNC)-derived mesenchymal cells surrounding soft palatal myogenic cells. Using Osr2-Cre;ß-cateninfl/fl mice, we show that Wnt signaling is indispensable for mesenchymal cell proliferation and subsequently for myogenesis through mediating ciliogenesis. Specifically, we have identified that Wnt signaling directly regulates expression of the ciliary gene Ttll3. Impaired ciliary disassembly leads to differentiation defects in mesenchymal cells and indirectly disrupts myogenesis through decreased expression of Dlk1, a mesenchymal cell-derived pro-myogenesis factor. Moreover, we show that siRNA-mediated reduction of Ttll3 expression partly rescues mesenchymal cell proliferation and myogenesis in the palatal explant cultures from Osr2-Cre;ß-cateninfl/fl embryos. This study highlights the role of Wnt signaling in palatogenesis through the control of ciliary homeostasis, which establishes a new mechanism for Wnt-regulated craniofacial morphogenesis.

Embryonic requirements for Tcf12 in the development of the mouse coronal suture.

A major feature of Saethre-Chotzen syndrome is coronal craniosynostosis, the fusion of the frontal and parietal bones at the coronal suture. It is caused by heterozygous loss-of-function mutations in either of the bHLH transcription factors TWIST1 and TCF12. Although compound heterozygous Tcf12; Twist1 mice display severe coronal synostosis, the individual role of Tcf12 had remained unexplored. Here, we show that Tcf12 controls several key processes in calvarial development, including the rate of frontal and parietal bone growth, and the boundary between sutural and osteogenic cells. Genetic analysis supports an embryonic requirement for Tcf12 in suture formation, as combined deletion of Tcf12 in embryonic neural crest and mesoderm, but not in postnatal suture mesenchyme, disrupts the coronal suture. We also detected asymmetric distribution of mesenchymal cells on opposing sides of the wild-type frontal and parietal bones, which prefigures later bone overlap at the sutures. In Tcf12 mutants, reduced asymmetry is associated with bones meeting end-on-end, possibly contributing to synostosis. Our results support embryonic requirements of Tcf12 in proper formation of the overlapping coronal suture.

Single-cell transcriptomic signatures and gene regulatory networks modulated by Wls in mammalian midline facial formation and clefts.

Formation of highly unique and complex facial structures is controlled by genetic programs that are responsible for the precise coordination of three-dimensional tissue morphogenesis. However, the underlying mechanisms governing these processes remain poorly understood. We combined mouse genetic and genomic approaches to define the mechanisms underlying normal and defective midfacial morphogenesis. Conditional inactivation of the Wnt secretion protein Wls in Pax3-expressing lineage cells disrupted frontonasal primordial patterning, cell survival and directional outgrowth, resulting in altered facial structures, including midfacial hypoplasia and midline facial clefts. Single-cell RNA sequencing revealed unique transcriptomic atlases of mesenchymal subpopulations in the midfacial primordia, which are disrupted in the conditional Wls mutants. Differentially expressed genes and cis-regulatory sequence analyses uncovered that Wls modulates and integrates a core gene regulatory network, consisting of key midfacial regulatory transcription factors (including Msx1, Pax3 and Pax7) and their downstream targets (including Wnt, Shh, Tgfß and retinoic acid signaling components), in a mesenchymal subpopulation of the medial nasal prominences that is responsible for midline facial formation and fusion. These results reveal fundamental mechanisms underlying mammalian midfacial morphogenesis and related defects at single-cell resolution.

Bioinspired In-Sensor Multimodal Fusion for Enhanced Spatial and Spatiotemporal Association.

Multimodal perception can capture more precise and comprehensive information compared with unimodal approaches. However, current sensory systems typically merge multimodal signals at computing terminals following parallel processing and transmission, which results in the potential loss of spatial association information and requires time stamps to maintain temporal coherence for time-series data. Here we demonstrate bioinspired in-sensor multimodal fusion, which effectively enhances comprehensive perception and reduces the level of data transfer between sensory terminal and computation units. By adopting floating gate phototransistors with reconfigurable photoresponse plasticity, we realize the agile spatial and spatiotemporal fusion under nonvolatile and volatile photoresponse modes. To realize an optimal spatial estimation, we integrate spatial information from visual-tactile signals. For dynamic events, we capture and fuse in real time spatiotemporal information from visual-audio signals, realizing a dance-music synchronization recognition task without a time-stamping process. This in-sensor multimodal fusion approach provides the potential to simplify the multimodal integration system, extending the in-sensor computing paradigm.

Generation of tamoxifen-inducible Tfap2b-CreERT2 mice using CRISPR-Cas9.

Tfap2b, a pivotal transcription factor, plays critical roles within neural crest cells and their derived lineage. To unravel the intricate lineage dynamics and contribution of these Tfap2b+ cells during craniofacial development, we established a Tfap2b-CreERT2 knock-in transgenic mouse line using the CRISPR-Cas9-mediated homologous direct repair. By breeding with tdTomato reporter mice and initiating Cre activity through tamoxifen induction at distinct developmental time points, we show the Tfap2b lineage within the key neural crest-derived domains, such as the facial mesenchyme, midbrain, cerebellum, spinal cord, and limbs. Notably, the migratory neurons stemming from the dorsal root ganglia are visible subsequent to Cre activity initiated at E8.5. Intriguingly, Tfap2b+ cells, serving as the progenitors for limb development, show activity predominantly commencing at E10.5. Across the mouse craniofacial landscape, Tfap2b exhibits a widespread presence throughout the facial organs. Here we validate its role as a marker of progenitors in tooth development and have confirmed that this process initiates from E12.5. Our study not only validates the Tfap2b-CreERT2 transgenic line, but also provides a powerful tool for lineage tracing and genetic targeting of Tfap2b-expressing cells and their progenitor in a temporally and spatially regulated manner during the intricate process of development and organogenesis.

Exploring caspase functions in mouse models.

Caspases are enzymes with protease activity. Despite being known for more than three decades, caspase investigation still yields surprising and fascinating information. Initially associated with cell death and inflammation, their functions have gradually been revealed to extend beyond, targeting pathways such as cell proliferation, migration, and differentiation. These processes are also associated with disease mechanisms, positioning caspases as potential targets for numerous pathologies including inflammatory, neurological, metabolic, or oncological conditions. While in vitro studies play a crucial role in elucidating molecular pathways, they lack the context of the body's complexity. Therefore, laboratory animals are an indispensable part of successfully understanding and applying caspase networks. This paper aims to summarize and discuss recent knowledge, understanding, and challenges in caspase knock-out mice.

Ror2-mediated non-canonical Wnt signaling regulates Cdc42 and cell proliferation during tooth root development.

The control of size and shape is an important part of regulatory process during organogenesis. Tooth formation is a highly complex process that fine-tunes the size and shape of the tooth, which are crucial for its physiological functions. Each tooth consists of a crown and one or more roots. Despite comprehensive knowledge of the mechanism that regulates early tooth crown development, we have limited understanding of the mechanism regulating root patterning and size during development. Here, we show that Ror2-mediated non-canonical Wnt signaling in the dental mesenchyme plays a crucial role in cell proliferation, and thereby regulates root development size in mouse molars. Furthermore, Cdc42 acts as a potential downstream mediator of Ror2 signaling in root formation. Importantly, activation of Cdc42 can restore cell proliferation and partially rescue the root development size defects in Ror2 mutant mice. Collectively, our findings provide novel insights into the function of Ror2-mediated non-canonical Wnt signaling in regulating tooth morphogenesis, and suggest potential avenues for dental tissue engineering.

Arid1a regulates cell cycle exit of transit-amplifying cells by inhibiting the Aurka-Cdk1 axis in mouse incisor.

Stem cells self-renew or give rise to transit-amplifying cells (TACs) that differentiate into specific functional cell types. The fate determination of stem cells to TACs and their transition to fully differentiated progeny is precisely regulated to maintain tissue homeostasis. Arid1a, a core component of the switch/sucrose nonfermentable complex, performs epigenetic regulation of stage- and tissue-specific genes that is indispensable for stem cell homeostasis and differentiation. However, the functional mechanism of Arid1a in the fate commitment of mesenchymal stem cells (MSCs) and their progeny is not clear. Using the continuously growing adult mouse incisor model, we show that Arid1a maintains tissue homeostasis through limiting proliferation, promoting cell cycle exit and differentiation of TACs by inhibiting the Aurka-Cdk1 axis. Loss of Arid1a overactivates the Aurka-Cdk1 axis, leading to expansion of the mitotic TAC population but compromising their differentiation ability. Furthermore, the defective homeostasis after loss of Arid1a ultimately leads to reduction of the MSC population. These findings reveal the functional significance of Arid1a in regulating the fate of TACs and their interaction with MSCs to maintain tissue homeostasis.

Lhx6 regulates canonical Wnt signaling to control the fate of mesenchymal progenitor cells during mouse molar root patterning.

Mammalian tooth crown formation has long served as a model for investigating how patterning and morphogenesis are orchestrated during development. However, the mechanism underlying root patterning and morphogenesis remains poorly understood. In this study, we find that Lhx6 labels a subpopulation of root progenitor cells in the apical dental mesenchyme, which is closely associated with furcation development. Loss of Lhx6 leads to furcation and root number defects, indicating that Lhx6 is a key root patterning regulator. Among the multiple cellular events regulated by Lhx6 is the odontoblast fate commitment of progenitor cells, which it controls in a cell-autonomous manner. Specifically, Lhx6 loss leads to elevated expression of the Wnt antagonist Sfrp2 and down-regulation of Wnt signaling in the furcation region, while overactivation of Wnt signaling in Lhx6+ progenitor cells partially restore the furcation defects in Lhx6-/- mice. Collectively, our findings have important implications for understanding organ morphogenesis and future strategies for tooth root regeneration.

A Self-Rectifying Synaptic Memristor Array with Ultrahigh Weight Potentiation Linearity for a Self-Organizing-Map Neural Network.

Two-terminal self-rectifying (SR)-synaptic memristors are preeminent candidates for high-density and efficient neuromorphic computing, especially for future three-dimensional integrated systems, which can self-suppress the sneak path current in crossbar arrays. However, SR-synaptic memristors face the critical challenges of nonlinear weight potentiation and steep depression, hindering their application in conventional artificial neural networks (ANNs). Here, a SR-synaptic memristor (Pt/NiOx/WO3-x:Ti/W) and cross-point array with sneak path current suppression features and ultrahigh-weight potentiation linearity up to 0.9997 are introduced. The image contrast enhancement and background filtering are demonstrated on the basis of the device array. Moreover, an unsupervised self-organizing map (SOM) neural network is first developed for orientation recognition with high recognition accuracy (0.98) and training efficiency and high resilience toward both noises and steep synaptic depression. These results solve the challenges of SR memristors in the conventional ANN, extending the possibilities of large-scale oxide SR-synaptic arrays for high-density, efficient, and accurate neuromorphic computing.

FaceBase 3: analytical tools and FAIR resources for craniofacial and dental research.

The FaceBase Consortium was established by the National Institute of Dental and Craniofacial Research in 2009 as a 'big data' resource for the craniofacial research community. Over the past decade, researchers have deposited hundreds of annotated and curated datasets on both normal and disordered craniofacial development in FaceBase, all freely available to the research community on the FaceBase Hub website. The Hub has developed numerous visualization and analysis tools designed to promote integration of multidisciplinary data while remaining dedicated to the FAIR principles of data management (findability, accessibility, interoperability and reusability) and providing a faceted search infrastructure for locating desired data efficiently. Summaries of the datasets generated by the FaceBase projects from 2014 to 2019 are provided here. FaceBase 3 now welcomes contributions of data on craniofacial and dental development in humans, model organisms and cell lines. Collectively, the FaceBase Consortium, along with other NIH-supported data resources, provide a continuously growing, dynamic and current resource for the scientific community while improving data reproducibility and fulfilling data sharing requirements.

Electrochemical Production of Glycolate Fuelled By Polyethylene Terephthalate Plastics with Improved Techno-Economics.

Electrochemical valorization of polyethylene terephthalate (PET) waste streams into commodity chemicals offers a potentially sustainable route for creating a circular plastic economy. However, PET wastes upcycling into valuable C2 product remains a huge challenge by the lack of an electrocatalyst that can steer the oxidation economically and selectively. Here, it is reported a catalyst comprising Pt nanoparticles hybridized with γ-NiOOH nanosheets supported on Ni foam (Pt/γ-NiOOH/NF) that favors electrochemical transformation of real-word PET hydrolysate into glycolate with high Faradaic efficiency (> 90%) and selectivity (> 90%) across wide reactant (ethylene glycol, EG) concentration ranges under a marginal applied voltage of 0.55 V, which can be paired with cathodic hydrogen production. Computational studies combined with experimental characterizations elucidate that the Pt/γ-NiOOH interface with substantial charge accumulation gives rise to an optimized adsorption energy of EG and a decreased energy barrier of potential determining step. A techno-economic analysis demonstrates that, with the nearly same amount of resource investment, the electroreforming strategy towards glycolate production can raise revenue by up to 2.2 times relative to conventional chemical process. This work may thus serve as a framework for PET wastes valorization process with net-zero carbon footprint and high economic viability.

Carrier Modulation in 2D Transistors by Inserting Interfacial Dielectric Layer for Area-Efficient Computation.

2D materials with atomic thickness display strong gate controllability and emerge as promising materials to build area-efficient electronic circuits. However, achieving the effective and nondestructive modulation of carrier density/type in 2D materials is still challenging because the introduction of dopants will greatly degrade the carrier transport via Coulomb scattering. Here, a strategy to control the polarity of tungsten diselenide (WSe2 ) field-effect transistors (FETs) via introducing hexagonal boron nitride (h-BN) as the interfacial dielectric layer is devised. By modulating the h-BN thickness, the carrier type of WSe2 FETs has been switched from hole to electron. The ultrathin body of WSe2 , combined with the effective polarity control, together contribute to the versatile single-transistor logic gates, including NOR, AND, and XNOR gates, and the operation of only two transistors as a half adder in logic circuits. Compared with the use of 12 transistors based on static Si CMOS technology, the transistor number of the half adder is reduced by 83.3%. The unique carrier modulation approach has general applicability toward 2D logic gates and circuits for the improvement of area efficiency in logic computation.

Reversing neural circuit and behavior deficit in mice exposed to maternal inflammation by Zika virus.

Zika virus (ZIKV) infection during pregnancy is linked to various developmental brain disorders. Infants who are asymptomatic at birth might have postnatal neurocognitive complications. However, animal models recapitulating these neurocognitive phenotypes are lacking, and the circuit mechanism underlying behavioral abnormalities is unknown. Here, we show that ZIKV infection during mouse pregnancy induces maternal immune activation (MIA) and leads to autistic-like behaviors including repetitive self-grooming and impaired social memory in offspring. In the medial prefrontal cortex (mPFC), ZIKV-affected offspring mice exhibit excitation and inhibition imbalance and increased cortical activity. This could be explained by dysregulation of inhibitory neurons and synapses, and elevated neural activity input from mPFC-projecting ventral hippocampus (vHIP) neurons. We find structure alterations in the synaptic connections and pattern of vHIP innervation of mPFC neurons, leading to hyperconnectivity of the vHIP-mPFC pathway. Decreasing the activity of mPFC-projecting vHIP neurons with a chemogenetic strategy rescues social memory deficits in ZIKV offspring mice. Our studies reveal a hyperconnectivity of vHIP to mPFC projection driving social memory deficits in mice exposed to maternal inflammation by ZIKV.

Current Understanding of the Regulatory Mechanism of Tooth Root Development and Future Perspectives.

Background: The purpose of this review article is to understand tooth root development and its regulation through evolution and epigenetics as well as future implications involving root regeneration and tissue engineering. Types of Studies Reviewed: we performed a comprehensive PubMed search to review all published studies related to the molecular regulation of tooth root development and regeneration until August 2022. Articles selected include original research studies and reviews. Results: Epigenetic regulation strongly influences dental tooth root patterning and development. One study highlights how genes such as Ezh2 and Arid1a are crucial components in the development of tooth root furcation patterning. Another study shows that loss of Arid1a ultimately leads to shortened root morphology. Furthermore, researchers are utilizing information about root development and stem cells to find alternative treatments in replacing missing teeth through a stem cell-mediated bioengineered tooth root (bio-root). Practical Implications: Dentistry values preserving natural tooth morphology. Presently, implants are the best treatment for replacing missing teeth, but alternative future treatments might include tissue engineering/bio-root regeneration to restore our dentition.

Defect-Assisted Anchoring of Pt Single Atoms on MoS2 Nanosheets Produces High-Performance Catalyst for Industrial Hydrogen Evolution Reaction.

Pt-based catalysts are currently the most efficient electrocatalysts for the hydrogen evolution reaction (HER), but the scarcity and high cost of Pt limit industrial applications. Downsizing Pt nanoparticles (NPs) to single atoms (SAs) can expose more active sites and increase atomic utilization, thus decreasing the cost. Here, a solar-irradiation strategy is used to prepare hybrid SA-Pt/MoS2 nanosheets (NSs) that demonstrate excellent HER activity (the overpotential at a current density of 10 mA cm-2 (η10 ) of 44 mV, and Tafel slope of 34.83 mV dec-1 in acidic media; η10 of 123 mV, and Tafel slope of 76.71 mV dec-1 in alkaline media). Defects and deformations introduced by thermal pretreatment of the hydrothermal MoS2 NSs promote anchoring and stability of Pt SAs. The fabrication of Pt SAs and NPs is easily controlled using different Pt-precursor concentrations. Moreover, SA-Pt/MoS2 produced under natural sunlight exhibits high HER performance (η10 of 55 mV, and Tafel slope of 43.54 mV dec-1 ), which indicates its viability for mass production. Theoretical simulations show that Pt improves the absorption of H atoms and the charge-transfer kinetics of MoS2 , which significantly enhance HER activity. A simple, inexpensive strategy for preparing SA-Pt/MoS2 hybrid catalysts for industrial HER is provided.

Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics.

Stretchable electronics find widespread uses in a variety of applications such as wearable electronics, on-skin electronics, soft robotics and bioelectronics. Stretchable electronic devices conventionally built with elastomeric thin films show a lack of permeability, which not only impedes wearing comfort and creates skin inflammation over long-term wearing but also limits the design form factors of device integration in the vertical direction. Here, we report a stretchable conductor that is fabricated by simply coating or printing liquid metal onto an electrospun elastomeric fibre mat. We call this stretchable conductor a liquid-metal fibre mat. Liquid metal hanging among the elastomeric fibres self-organizes into a laterally mesh-like and vertically buckled structure, which offers simultaneously high permeability, stretchability, conductivity and electrical stability. Furthermore, the liquid-metal fibre mat shows good biocompatibility and smart adaptiveness to omnidirectional stretching over 1,800% strain. We demonstrate the use of a liquid-metal fibre mat as a building block to realize highly permeable, multifunctional monolithic stretchable electronics.