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Polystyrene microplastics (mic-PS) have become harmful pollutants that attracted substantial attention about their potential toxicity. Hydrogen sulfide (H2S) is the third reported endogenous gas transmitter with protective functions on numerous physiologic responses. Nevertheless, the roles for mic-PS on skeletal systems in mammals and the protective effects of exogenous H2S are still indistinct. Here, the proliferation of MC3T3-E1 cell was analyzed by CCK8. Gene changes between the control and mic-PS treatment groups were analyzed by RNA-seq. The mRNA expression of bone morphogenetic protein 4 (Bmp4), alpha cardiac muscle 1 (Actc1), and myosin heavy polypeptide 6 (Myh6) was analyzed by QPCR. ROS level was analyzed by 2 ′ ,7 ′ -dichlorofluorescein (DCFH-DA). The mitochondrial membrane potential (MMP) was analyzed by Rh123. Our results indicated after exposure for 24 h, 100 mg/L mic-PS induced considerable cytotoxicity in the osteoblastic cells of mice. There were 147 differentially expressed genes (DEGs) including 103 downregulated genes and 44 upregulated genes in the mic-PS-treated group versus the control. The related signaling pathways were oxidative stress, energy metabolism, bone formation, and osteoblast differentiation. The results indicate that exogenous H2S may relieve mic-PS toxicity by altering Bmp4, Actc1, and Myh6 mRNA expressions associated with mitochondrial oxidative stress. Taken together, this study demonstrated that the bone toxicity effects of mic-PS along with exogenous H2S have protective function in mic-PS-mediated oxidative damage and mitochondrial dysfunction in osteoblastic cells of mice.

In the wake of the Coronavirus disease (COVID-19) pandemic, chest computed tomography (CT) has become an invaluable component in the rapid and accurate detection of COVID-19. CT scans traditionally require manual inspections from medical professionals, which is expensive and tedious. With advancements in machine learning, deep neural networks have been applied to classify CT scans for efficient diagnosis. However, three challenges hinder this application of deep learning: (1) Domain shift across CT platforms and human subjects impedes the performance of neural networks in different hospitals. (2) Unsupervised Domain Adaptation (UDA), the traditional method to overcome domain shift, typically requires access to both source and target data. This is not realistic in COVID-19 diagnosis due to the sensitivity of medical data. The privacy of patients must be protected. (3) Data imbalance may exist between easy/hard samples and between data classes which can overwhelm the training of deep networks, causing degenerate models. To overcome these challenges, we propose a Cross-Platform Privacy-Preserving COVID-19 diagnosis network (CP 3 Net) that integrates domain adaptation, self-supervised learning, imbalanced label learning, and rotation classifier training into one synergistic framework. We also create a new CT benchmark by combining real-world datasets from multiple medical platforms to facilitate the cross-domain evaluation of our method. Through extensive experiments, we demonstrate that CP 3 Net outperforms many popular UDA methods and achieves state-of-the-art results in diagnosing COVID-19 using CT scans. Nanyang Technological University This work is supported by NTU Presidential Postdoctoral Fellowship, ‘‘Adaptive Multimodal Learning for Robust Sensing and Recognition in Smart Cities’’ project fund, at Nanyang Technological University, Singapore.

The mechanisms by which lower limb ischemia/reperfusion induces acute kidney injury (AKI) remain largely uncharacterized. We hypothesized that tourniquet-induced lower limb ischemia/reperfusion (TILLIR) would inhibit mitochondrial function in the renal cortex. We used a murine model to show that TILLIR of the high thigh regions inflicted time-dependent AKI as determined by renal function and histology. This effect was associated with decreased activities of mitochondrial complexes I, II, V and citrate synthase in the kidney cortex. Moreover, TILLIR reduced mRNA levels of a master regulator of mitochondrial biogenesis PGC-1α, and its downstream genes NDUFS1 and ATP5o in the renal cortex. TILLIR also increased serum corticosterone concentrations. TILLIR did not significantly affect protein levels of the critical regulators of mitophagy PINK1 and PARK2, mitochondrial transport proteins Tom20 and Tom70, or heat-shock protein 27. TILLIR had no significant effect on mitochondrial oxidative stress as determined by mitochondrial ability to generate reactive oxygen species, protein carbonylation, or protein levels of MnSOD and peroxiredoxin1. However, TILLIR inhibited classic autophagic flux by increasing p62 protein abundance and preventing the conversion of LC3-I to LC3-II. TILLIR increased phosphorylation of cytosolic and mitochondrial ERK1/2 and mitochondrial AKT1, as well as mitochondrial SGK1 activity. In conclusion, lower limb ischemia/reperfusion induces distal AKI by inhibiting mitochondrial function through reducing mitochondrial biogenesis. This AKI occurs without significantly affecting PINK1-PARK2-mediated mitophagy or mitochondrial oxidative stress in the kidney cortex.

SUMMARYAging is an intricate process that is characterized by multiple hallmarks including stem cell exhaustion, genome instability, epigenome alteration, impaired proteostasis, and cellular senescence. While each of these traits is detrimental at the cellular level, it remains unclear how they are interconnected to cause systemic organ deterioration. Here we show that abrogating Brap, a BRCA1 associated protein important for neurogenesis, results in cellular senescence with persistent DNA double-strand breaks and elevation of histone H2A mono- and poly-ubiquitination (H2Aub). The high H2Aub initiates histone proteolysis, leading to both epigenetic alteration and proteasome overflow. These defects induce neuroinflammation, impair proteostasis, accelerate neurodegeneration, and substantially shorten lifespan in mice carrying Brap deletions in the brain. We further show H2Aub is also increased in human brain tissues of Alzheimer’s disease. These data together suggest that chromatin aberrations mediated by H2Aub act as a nexus of multiple aging hallmarks and promote tissue-wide degeneration.

As an important factor in the landscape experience, color has attracted more and more attention. This paper investigates and collects the color application of the ancient Shu cultural landscape in five sites where the development of ancient Shu culture is relatively mature. Based on the quantitative analysis of the data, it is concluded that there are some problems between landscape’s subject and carrier colors in hue, value and chroma. Meanwhile, the corresponding suggestions are also made.

Diabetic foot ulcer's impaired wound healing, which leads to the development of chronic non-healing wounds and ultimately amputation, is a major problem worldwide. Although recently endothelial progenitor cell-derived cell therapy has been used as a therapeutic intervention to treat diabetic wounds, thereby promoting neovascularization, the results, however, are not satisfactory. In this article, we have discussed the several steps that are involved in the neovascularization process, which might be impaired during diabetes. In addition, we have also discussed the reported possible interventions to correct these impairments. Thus, we have summarized neovascularization as a process with a coordinated sequence of multiple steps and thus, there is the need of a combined therapeutic approach to achieve better treatment outcomes.

SummaryRegulating cell proliferation and differentiation in CNS development requires both extraordinary complexity and precision. Neural progenitors receive graded overlapping signals from midline signaling centers, yet each makes a unique cell fate decision in a spatiotemporally restricted pattern. The Nde1-Lis1 complex regulates individualized cell fate decisions based on the geographical location with respect to the midline. While cells distant from the midline fail to self-renew in the Nde1-Lis1 double-mutant CNS, cells embedded in the signaling centers showed marked overproliferation. A direct interaction between Lis1 and Brap, a mitogen-activated protein kinase (MAPK) signaling threshold modulator, mediates this differential response to mitogenic signal gradients. Nde1-Lis1 deficiency resulted in a spatially dependent alteration of MAPK scaffold Ksr and hyperactivation of MAPK. Epistasis analyses supported synergistic Brap and Lis1 functions. These results suggest that a molecular complex composed of Nde1, Lis1, and Brap regulates the dynamic MAPK signaling threshold in a spatially dependent fashion.

Filamins are a family of actin-binding proteins responsible for diverse biological functions in the context of regulating actin dynamics and vesicle trafficking. Disruption of these proteins has been implicated in multiple human developmental disorders. To investigate the roles of different filamin isoforms, we focused on FlnA and FlnB interactions in the cartilage growth plate, since mutations in both molecules cause chondrodysplasias. Current studies show that FlnA and FlnB share a common function in stabilizing the actin cytoskeleton, they physically interact in the cytoplasm of chondrocytes, and loss of FlnA enhances FlnB expression of chondrocytes in the growth plate (and vice versa), suggesting compensation. Prolonged FlnB loss, however, promotes actin-stress fiber formation following plating onto an integrin activating substrate whereas FlnA inhibition leads to decreased actin formation. FlnA more strongly binds RhoA, although both filamins overlap with RhoA expression in the cell cytoplasm. FlnA promotes RhoA activation whereas FlnB indirectly inhibits this pathway. Moreover, FlnA loss leads to diminished expression of β1-integrin, whereas FlnB loss promotes integrin expression. Finally, fibronectin mediated integrin activation has been shown to activate RhoA and activated RhoA leads to stress fiber formation and cell spreading. Fibronectin stimulation in null FlnA cells impairs enhanced spreading whereas FlnB inhibited cells show enhanced spreading. While filamins serve a primary static function in stabilization of the actin cytoskeleton, these studies are the first to demonstrate a dynamic and antagonistic relationship between different filamin isoforms in the dynamic regulation of integrin expression, RhoGTPase activity and actin stress fiber remodeling.

Neuronal fate-restricted intermediate progenitors (IPs) are derived from the multipotent radial glia (RGs) and serve as the direct precursors for cerebral cortical neurons, but factors that control their neurogenic plasticity remain elusive. Here we report that IPs’ neuron production is enhanced by abrogating filamin function, leading to the generation of periventricular neurons independent of normal neocortical neurogenesis and neuronal migration. Loss of Flna in neural progenitor cells (NPCs) led RGs to undergo changes resembling epithelial-mesenchymal transition (EMT) along with exuberant angiogenesis that together changed the microenvironment and increased neurogenesis of IPs. We show that by collaborating with β-arrestin, Flna maintains the homeostatic signaling between the vasculature and NPCs, and loss of this function results in escalated Vegfa and Igf2 signaling, which exacerbates both EMT and angiogenesis to further potentiate IPs’ neurogenesis. These results suggest that the neurogenic potential of IPs may be boosted in vivo by manipulating Flna-mediated neurovascular communication. DOI: http://dx.doi.org/10.7554/eLife.17823.001

Genes disrupted in human microcephaly (meaning "small brain") define key regulators of neural progenitor proliferation and cell-fate specification. In comparison, genes mutated in human lissencephaly (lissos means smooth and cephalos means brain) highlight critical regulators of neuronal migration. Here, we report two families with extreme microcephaly and grossly simplified cortical gyral structure, a condition referred to as microlissencephaly, and show that they carry homozygous frameshift mutations in NDE1, which encodes a multidomain protein that localizes to the centrosome and mitotic spindle poles. Both human mutations in NDE1 truncate the C-terminal NDE1domains, which are essential for interactions with cytoplasmic dynein and thus for regulation of cytoskeletal dynamics in mitosis and for cell-cycle-dependent phosphorylation of NDE1 by Cdk1. We show that the patient NDE1 proteins are unstable, cannot bind cytoplasmic dynein, and do not localize properly to the centrosome. Additionally, we show that CDK1 phosphorylation at T246, which is within the C-terminal region disrupted by the mutations, is required for cell-cycle progression from the G2 to the M phase. The role of NDE1 in cell-cycle progression probably contributes to the profound neuronal proliferation defects evident in Nde1-null mice and patients with NDE1 mutations, demonstrating the essential role of NDE1 in human cerebral cortical neurogenesis.

Neurons in the cerebral cortex originate predominantly from asymmetrical divisions of polarized radial glial or neuroepithelial cells. Fate control of neural progenitors through regulating cell division asymmetry determines the final cortical neuronal number and organization. Haploinsufficiency of human LIS1 results in type I lissencephaly (smooth brain) with severely reduced surface area and laminar organization of the cerebral cortex. Here we show that LIS1 and its binding protein Nde1 (mNudE) regulate the fate of radial glial progenitors collaboratively. Mice with an allelic series of Lis1 and Nde1 double mutations displayed a striking dose-dependent size reduction and de-lamination of the cerebral cortex. The neocortex of the Lis1-Nde1 double mutant mice showed over 80% reduction in surface area and inverted neuronal layers. Dramatically increased neuronal differentiation at the onset of corticogenesis in the mutant led to overproduction and abnormal development of earliest-born preplate neurons and Cajal-Retzius cells at the expense of progenitors. While both Lis1 and Nde1 are known to regulate the mitotic spindle orientation, only a moderate alteration in mitotic cleavage orientation was detected in the Lis1-Nde1 double deficient progenitors. Instead, a striking change in the morphology of metaphase progenitors with reduced apical attachment to the ventricular surface and weakened lateral contacts to neighboring cells appear to hinder the accurate control of cell division asymmetry and underlie the dramatically increased neuronal differentiation. Our data suggest that maintaining the shape and cell-cell interactions of radial glial neuroepithelial progenitors by the Lis1-Nde1 complex is essential for their self renewal during the early phase of corticogenesis.

LIS1 and nuclear distribution gene E (NudE) are partner proteins in a conserved pathway regulating the function of dynein and microtubules. Here, we present data that cytoplasmic LEK1 (cytLEK1), a large protein containing a spectrin repeat and multiple leucine zippers, is a component of this pathway through its direct interaction with NudE, as determined by a yeast two-hybrid screen. We identified the binding domains in each molecule, and coimmunoprecipitation and colocalization studies confirmed the specificity of the interaction between cytLEK1 and NudE. Confocal deconvolution analysis revealed that cytLEK1 exhibits colocalization with endogenous NudE and with the known NudE binding partners, LIS1 and dynein. By localizing the NudE-binding domain of cytLEK1 to a small domain within the molecule, we were able to disrupt cytLEK1 function by using a dominant negative approach in addition to LEK1 knockdown and, thus, examine the role of the cytLEK1–NudE interaction in cells. Consistent with a defect in the LIS1 pathway, disruption of cytLEK1 function resulted in alteration of microtubule organization and cellular shape. The microtubule network of cells became tightly focused around the nucleus and resulted in a rounded cell shape. Additionally, cells exhibited a severe inability to repolymerize their microtubule networks after nocodazole challenge. Taken together, our studies revealed that cytLEK1 is essential for cellular functions regulated by the LIS1 pathway.

Ablation of the LIS1-interacting protein Nde1 (formerly mNudE) in mouse produces a small brain (microcephaly), with the most dramatic reduction affecting the cerebral cortex. While cortical lamination is mostly preserved, the mutant cortex has fewer neurons and very thin superficial cortical layers (II to IV). BrdU birthdating revealed retarded and modestly disorganized neuronal migration; however, more dramatic defects on mitotic progression, mitotic orientation, and mitotic chromosome localization in cortical progenitors were observed in Nde1 mutant embryos. The small cerebral cortex seems to reflect both reduced progenitor cell division and altered neuronal cell fates. In vitro analysis demonstrated that Nde1 is essential for centrosome duplication and mitotic spindle assembly. Our data show that mitotic spindle function and orientation are essential for normal development of mammalian cerebral cortex.

The doublecortin-like domains (DCX), which typically occur in tandem, are novel microtubule-binding modules. DCX tandems are found in doublecortin, a 360-residue protein expressed in migrating neurons; the doublecortin-like kinase (DCLK); the product of the RP1 gene that is responsible for a form of inherited blindness; and several other proteins. Mutations in the gene encoding doublecortin cause lissencephaly in males and the 'double-cortex syndrome' in females. We here report a solution structure of the N-terminal DCX domain of human doublecortin and a 1.5 A resolution crystal structure of the equivalent domain from human DCLK. Both show a stable, ubiquitin-like tertiary fold with distinct structural similarities to GTPase-binding domains. We also show that the C-terminal DCX domains of both proteins are only partially folded. In functional assays, the N-terminal DCX domain of doublecortin binds only to assembled microtubules, whereas the C-terminal domain binds to both microtubules and unpolymerized tubulin.

Mutations in the X-linked gene Filamin A (FLNA) lead to the human neurological disorder, periventricular heterotopia (PH). Although PH is characterized by a failure in neuronal migration into the cerebral cortex with consequent formation of nodules in the ventricular and subventricular zones, many neurons appear to migrate normally, even in males, suggesting compensatory mechanisms. Here we characterize expression patterns for FlnA and a highly homologous protein Filamin B (FlnB) within the nervous system, in order to better understand their potential roles in cortical development. FlnA mRNA was widely expressed in all cortical layers while FlnB mRNA was most highly expressed in the ventricular and subventricular zones during development. In adulthood, widespread but reduced expression of FlnA and FlnB persisted throughout the cerebral cortex. FlnA and FlnB proteins were highly expressed in both the leading processes and somata of migratory neurons during corticogenesis. Postnatally, FlnA immunoreactivity was largely localized to the cell body with FlnB in the soma and neuropil during neuronal differentiation. In adulthood, diminished expression of both proteins localized to the cell soma and nucleus. Moreover, the putative FLNB homodimerization domain strongly interacted with itself or the corresponding homologous region of FLNA by yeast two-hybrid interaction, the two proteins co-localized within neuronal precursors by immunocytochemistry and the existence of FLNA-FLNB heterodimers could be detected by co-immunoprecipitation. These results suggest that FLNA and FLNB may form both homodimers and heterodimers and that their interaction could potentially compensate for the loss of FLNA function during cortical development within PH individuals.

Aims We hypothesized that the structure and function of the mature valves is largely dependent upon how these tissues are built during development, and defects in how the valves are built can lead to the pathological progression of a disease phenotype. Thus, we sought to uncover potential developmental origins and mechanistic underpinnings causal to myxomatous mitral valve disease. We focus on how filamin-A, a cytoskeletal binding protein with strong links to human myxomatous valve disease, can function as a regulatory interface to control proper mitral valve development. Methods and results Filamin-A-deficient mice exhibit abnormally enlarged mitral valves during foetal life, which progresses to a myxomatous phenotype by 2 months of age. Through expression studies, in silico modelling, 3D morphometry, biochemical studies, and 3D matrix assays, we demonstrate that the inception of the valve disease occurs during foetal life and can be attributed, in part, to a deficiency of interstitial cells to efficiently organize the extracellular matrix (ECM). This ECM organization during foetal valve gestation is due, in part, to molecular interactions between filamin-A, serotonin, and the cross-linking enzyme, transglutaminase-2 (TG2). Pharmacological and genetic perturbations that inhibit serotonin-TG2-filamin-A interactions lead to impaired ECM remodelling and engender progression to a myxomatous valve phenotype. Conclusions These findings illustrate a molecular mechanism by which valve interstitial cells, through a serotonin, TG, and filamin-A pathway, regulate matrix organization during foetal valve development. Additionally, these data indicate that disrupting key regulatory interactions during valve development can set the stage for the generation of postnatal myxomatous valve disease.

A bang-sensitive enhancer trap line was isolated in a behavioral screen. The flies show a weak bang-sensitive paralysis, recovering after about 7 s. The P element insert is localized at 93131-2 on the salivary chromosomes, the site of the (Na + ,K + )ATPase a subunit gene. Molecular characterization demonstrates that the transposon is inserted into the first intron of this gene. This insertion leads to normal-sized transcripts, but reduced levels of expression. This change is also reflected in lower amounts of a normal-sized a subunit protein. Mutant flies show a much greater sensitivity to ouabain, likewise indicating, on a functional level, a reduction in Na + pump activity. Furthermore, the bang-sensitive behavior can also be mimicked by injecting sublethal doses of ouabain into wild-type flies. The molecular and functional evidence indicates that the insertion has produced a hypomorphic mutation of the (Na + ,K + )ATPase α subunit gene, opening the way to future studies of the regulation of the Na + pump.

Lis1-Nde1 integrates cerebral cortical neurogenesis with neuronal migration by stabilizing the basal-lateral surface of radial glial cells., Radial glial cells (RGCs) are distinctive neural stem cells with an extraordinary slender bipolar morphology and dual functions as precursors and migration scaffolds for cortical neurons. Here we show a novel mechanism by which the Lis1-Nde1 complex maintains RGC functions through stabilizing the dystrophin/dystroglycan glycoprotein complex (DGC). A direct interaction between Nde1 and utrophin/dystrophin allows for the assembly of a multi-protein complex that links the cytoskeleton to the extracellular matrix of RGCs to stabilize their lateral membrane, cell-cell adhesion, and radial morphology. Lis1-Nde1 mutations destabilized the DGC and resulted in deformed, disjointed RGCs and disrupted basal lamina. Besides impaired RGC self-renewal and neuronal migration arrests, Lis1-Nde1 deficiencies also led to neuronal over-migration. Additional to phenotypic resemblances of Lis1-Nde1 with DGC, strong synergistic interactions were found between Nde1 and dystroglycan in RGCs. As functional insufficiencies of LIS1, NDE1, and dystroglycan all cause lissencephaly syndromes, our data demonstrated that a three-dimensional regulation of RGC's cytoarchitecture by the Lis1-Nde1-DGC complex determines the number and spatial organization of cortical neurons as well as the size and shape of the cerebral cortex., Author Summary The processes of neurogenesis and neuronal migration within the developing cerebral cortex must be tightly orchestrated to enable ordered generation and transportation of neurons to designated cortical layers. The mechanism by which these two processes are integrated remains elusive. Radial glial cells, the major neural stem cells in the developing brain, serve both as progenitors and migration scaffolds for cortical neurons as they migrate. The cortical developmental disease lissencephaly (smooth brain) is a result of defects in neurogenesis and neuronal migration, and is associated with the protein LIS1 and its binding partner NDE1. In this study, we show that several key players in human cerebral cortical development, including LIS1, NDE1, dystrophin, and dystroglycan, form a molecular complex to regulate cortical neurogenesis and neuronal migration in a mouse model. This multi-protein complex is active on the basal-lateral surface of radial glial cells, which is known to provide guidance to migrating neurons. When we depleted NDE1 in mice, dystrophin and dystroglycan were lost from the membrane and radial glial cells were deformed, indicating the importance of the multi-protein complex for proper cell morphology. This effect on morphology resulted in a loss of normal migration and cortical phenotypes similar to lissencephaly. Our findings suggest that genes that regulate the structure and function of the basal-lateral membrane of radial glial cells may integrate the dual functions of these cells and determine the size, shape, and function of the cerebral cortex.

Mutations in the human Filamin A ( FLNA ) gene disrupt neuronal migration to the cerebral cortex and cause cardiovascular defects. Complete loss of Flna in mice results in embryonic lethality with severe cardiac structural defects involving ventricles, atria, and outflow tracts, as well as widespread aberrant vascular patterning. Despite these widespread developmental defects, migration and motility of many cell types does not appear to be affected. Instead, Flna-null embryos display abnormal epithelial and endothelial organization and aberrant adherens junctions in developing blood vessels, heart, brain, and other tissues. Essential roles for FLNA in intercellular junctions provide a mechanism for the diverse developmental defects seen in patients with FLNA mutations.

Cells in mechanically challenged environments must cope with high amplitude forces to maintain cell viability and tissue homeostasis. Currently, force-induced cell death and the identity of mechanoprotective factors are not defined. We examined death in cultured periodontal fibroblasts, connective tissue cells that are exposed to heavy applied forces in vivo. Static tensile forces (0.48 piconewtons/microm2 cell area) were applied through magnetite beads coated with collagen or bovine serum albumin. There was a time-dependent increase of the percentage of propidium iodide-permeable cells in force-loaded cultures incubated with collagen but not bovine serum albumin beads, indicating a role for integrins. Cells exhibited reduced mitochondrial membrane potential, increased caspase-3 activation, nuclear condensation, terminal deoxynucleotidyl transferase nick end labeling staining, and detachment from the culture dish. The caspase-3 inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde reduced detachment 3-fold. There was a rapid (

Neuronal migration, like the migration of many cell types, requires an extensive rearrangement of cell shape, mediated by changes in the cytoskeleton. The genetic analysis of human brain malformations has identified several biochemical players in this process, including doublecortin (DCX) and LIS1, mutations of which cause a profound migratory disturbance known as lissencephaly ('smooth brain') in humans. Studies in mice have identified additional molecules such as Cdk5, P35, Reelin, Disabled and members of the LDL superfamily of receptors. Understanding the cell biology of these molecules has been a challenge, and it is not known whether they function in related biochemical pathways or in very distinct processes. The last year has seen rapid advances in the biochemical analysis of several such molecules. This analysis has revealed roles for some of these molecules in cytoskeletal regulation and has shown an unexpected conservation of the genetic pathways that regulate neuronal migration in humans and nuclear movement in simple eukaryotic organisms.

LIS1, a microtubule-associated protein, is required for neuronal migration, but the precise mechanism of LIS1 function is unknown. We identified a LIS1 interacting protein encoded by a mouse homolog of NUDE, a nuclear distribution gene in A. nidulans and a multicopy suppressor of the LIS1 homolog, NUDF. mNudE is located in the centrosome or microtubule organizing center (MTOC), and interacts with six different centrosomal proteins. Overexpression of mNudE dissociates γ-tubulin from the centrosome and disrupts microtubule organization. Missense mutations that disrupt LIS1 function block LIS1-mNudE binding. Moreover, misexpression of the LIS1 binding domain of mNudE in Xenopus embryos disrupts the architecture and lamination of the CNS. Thus, LIS1-mNudE interactions may regulate neuronal migration through dynamic reorganization of the MTOC.

How mitotic cell fate is regulated in the developing mammalian CNS is an important but largely unanswered question. Recently reporting in Neuron, Godin et al. showed that Huntingtin, the protein mutated in Huntington's disease, is required for both cerebral cortical neurogenesis and mitotic spindle function in neural progenitors.

Long-range, directed migration is particularly dramatic in the cerebral cortex, where postmitotic neurons generated deep in the brain migrate to form layers with distinct form and function. In the X-linked dominant human disorder periventricular heterotopia (PH), many neurons fail to migrate and persist as nodules lining the ventricular surface. Females with PH present with epilepsy and other signs, including patent ductus arteriosus and coagulopathy, while hemizygous males die embryonically. We have identified the PH gene as filamin 1 ( FLN1 ), which encodes an actin-cross-linking phosphoprotein that transduces ligand–receptor binding into actin reorganization, and which is required for locomotion of many cell types. FLN1 shows previously unrecognized, high-level expression in the developing cortex, is required for neuronal migration to the cortex, and is essential for embryogenesis.

The inv(16) chromosomal aberration is found in 10% of the cases with AML. The resultant CBFB-MYH11 fusion gene that plays a key-role in the leukemia development, but for full transformation, additional genetic hits are necessary. We report that the MYH11 gene overlaps with the NDE1 gene. At their 3 prime ends the genes overlap at the genomic, transcript as well as coding level and as a consequence, the inv(16) disrupts NDE1 in addition to CBFB and MYH11 in 90% of CBFB-MYH11 positive cases. To determine the relevance of Nde1 function in hematopoiesis leukemia development, hematopoiesis was studied in Nde1-/− and Nde1+/− mutant mice. A significant percentage of the Nde1 null mutant mice developed a myeloproliferative (MPD) phenotype at 6–12 months of age. This phenotype was observed in 6 out of 15 (40%) Nde1−/− mice, 2 out of 15 (13%) Nde1+/− mice and none of 4 wild type mice. All mice with the MPD phenotype exhibited a profound splenomegaly with spleen sizes ranging from 5 to 20-fold larger than normal wild type controls. Histopathological analysis demonstrated hypercellular bone marrow, effacement of normal splenic architecture with expansion of a myeloid cells, and infiltration of proliferating myeloid cells in various organs . A 10-fold increase in Gr1+/Mac1+ double positive mature myeloid cells in the spleen was confirmed by flow-cytometric analysis. Peripheral blood analyses showed that the white blood cell counts were slightly elevated in Nde1 mutant mice that had not yet developed a MPD phenotype compared to wild type mice. A somewhat higher white blood cell count was observed in Nde1 mutant mice with MPD phenotype. In the Nde1 mutant mice with or without splenomegaly we did not observe an increase in the number of B- and T-cells as measured by flowcytometer using various lymphoid cell surface markers. Based on these data we conclude that loss of Nde1 function and Nde1 haploinsufficiency results in the onset of a MPD phenotype. Earlier studies showed that Nde1 is a centrosomal protein. To test whether Nde1 is involved in spindle pole formation and chromosome segregation, we analyzed the mitotic behaviour of mouse embryo fibroblasts (MEFs). From passage 3 to passage 10, aneuploid metaphases increased much more rapidly in Nde1−/− MEFs than in the wild type controls. In addition, a broader spectrum of abnormal chromosome numbers was seen in Nde1−/− MEFs. Thus, Nde1 deficiency results in chromosomal instability. To study whether the numerical chromosome abnormalities were associated with aberrant spindle formation we stained Nde1−/− MEFs with a monoclonal antibody against tubulin. Multipolar spindles and misassembled spindles were more frequently observed in Nde1−/− MEFs compared to wild type cells. We conclude that the abnormal chromosomal segregation of Nde1−/− MEFs is associated with defective mitotic spindle structure. Since Nde1 is disrupted in the majority of inv(16) positive AML patients and the disruption in mice resulted in genetic instability and the onset of myeloproliferative disease, we suggest that the disruption of Nde1 in inv(16)+ AML may serve as additional genetic defect that contributes to leukemogenesis.