Kevin Kelley

All Publications

• Maturation and circuit integration of transplanted human cortical organoids. Nature Revah, O., Gore, F., Kelley, K. W., Andersen, J., Sakai, N., Chen, X., Li, M. Y., Birey, F., Yang, X., Saw, N. L., Baker, S. W., Amin, N. D., Kulkarni, S., Mudipalli, R., Cui, B., Nishino, S., Grant, G. A., Knowles, J. K., Shamloo, M., Huguenard, J. R., Deisseroth, K., Pașca, S. P. 2022; 610 (7931): 319-326

  Abstract

  Self-organizing neural organoids represent a promising in vitro platform with which to model human development and disease1-5. However, organoids lack the connectivity that exists in vivo, which limits maturation and makes integration with other circuits that control behaviour impossible. Here we show that human stem cell-derived cortical organoids transplanted into the somatosensory cortex of newborn athymic rats develop mature cell types that integrate into sensory and motivation-related circuits. MRI reveals post-transplantation organoid growth across multiple stem cell lines and animals, whereas single-nucleus profiling shows progression of corticogenesis and the emergence of activity-dependent transcriptional programs. Indeed, transplanted cortical neurons display more complex morphological, synaptic and intrinsic membrane properties than their in vitro counterparts, which enables the discovery of defects in neurons derived from individuals with Timothy syndrome. Anatomical and functional tracings show that transplanted organoids receive thalamocortical and corticocortical inputs, and in vivo recordings of neural activity demonstrate that these inputs can produce sensory responses in human cells. Finally, cortical organoids extend axons throughout the rat brain and their optogenetic activation can drive reward-seeking behaviour. Thus, transplanted human cortical neurons mature and engage host circuits that control behaviour. We anticipate that this approach will be useful for detecting circuit-level phenotypes in patient-derived cells that cannot otherwise be uncovered.

  View details for DOI 10.1038/s41586-022-05277-w

  View details for PubMedID 36224417

• Human brain organogenesis: Toward a cellular understanding of development and disease. Cell Kelley, K. W., Pașca, S. P. 2021

  Abstract

  The construction of the human nervous system is a distinctly complex although highly regulated process. Human tissue inaccessibility has impeded a molecular understanding of the developmental specializations from which our unique cognitive capacities arise. A confluence of recent technological advances in genomics and stem cell-based tissue modeling is laying the foundation for a new understanding of human neural development and dysfunction in neuropsychiatric disease. Here, we review recent progress on uncovering the cellular and molecular principles of human brain organogenesis in vivo as well as using organoids and assembloids in vitro to model features of human evolution and disease.

  View details for DOI 10.1016/j.cell.2021.10.003

  View details for PubMedID 34774127

• Variation among intact tissue samples reveals the core transcriptional features of human CNS cell classes. Nature neuroscience Kelley, K. W., Nakao-Inoue, H., Molofsky, A. V., Oldham, M. C. 2018; 21 (9): 1171-1184

  Abstract

  It is widely assumed that cells must be physically isolated to study their molecular profiles. However, intact tissue samples naturally exhibit variation in cellular composition, which drives covariation of cell-class-specific molecular features. By analyzing transcriptional covariation in 7,221 intact CNS samples from 840 neurotypical individuals, representing billions of cells, we reveal the core transcriptional identities of major CNS cell classes in humans. By modeling intact CNS transcriptomes as a function of variation in cellular composition, we identify cell-class-specific transcriptional differences in Alzheimer's disease, among brain regions, and between species. Among these, we show that PMP2 is expressed by human but not mouse astrocytes and significantly increases mouse astrocyte size upon ectopic expression in vivo, causing them to more closely resemble their human counterparts. Our work is available as an online resource ( http://oldhamlab.ctec.ucsf.edu/ ) and provides a generalizable strategy for determining the core molecular features of cellular identity in intact biological systems.

  View details for DOI 10.1038/s41593-018-0216-z

  View details for PubMedID 30154505

  View details for PubMedCentralID PMC6192711

• Kir4.1-Dependent Astrocyte-Fast Motor Neuron Interactions Are Required for Peak Strength. Neuron Kelley, K. W., Ben Haim, L., Schirmer, L., Tyzack, G. E., Tolman, M., Miller, J. G., Tsai, H. H., Chang, S. M., Molofsky, A. V., Yang, Y., Patani, R., Lakatos, A., Ullian, E. M., Rowitch, D. H. 2018; 98 (2): 306-319.e7

  Abstract

  Diversified neurons are essential for sensorimotor function, but whether astrocytes become specialized to optimize circuit performance remains unclear. Large fast α-motor neurons (FαMNs) of spinal cord innervate fast-twitch muscles that generate peak strength. We report that ventral horn astrocytes express the inward-rectifying K+ channel Kir4.1 (a.k.a. Kcnj10) around MNs in a VGLUT1-dependent manner. Loss of astrocyte-encoded Kir4.1 selectively altered FαMN size and function and led to reduced peak strength. Overexpression of Kir4.1 in astrocytes was sufficient to increase MN size through activation of the PI3K/mTOR/pS6 pathway. Kir4.1 was downregulated cell autonomously in astrocytes derived from amyotrophic lateral sclerosis (ALS) patients with SOD1 mutation. However, astrocyte Kir4.1 was dispensable for FαMN survival even in the mutant SOD1 background. These findings show that astrocyte Kir4.1 is essential for maintenance of peak strength and suggest that Kir4.1 downregulation might uncouple symptoms of muscle weakness from MN cell death in diseases like ALS.

  View details for DOI 10.1016/j.neuron.2018.03.010

  View details for PubMedID 29606582

  View details for PubMedCentralID PMC5919779

• CLARIFYING THE MOLECULAR CONSEQUENCES OF ONCOGENIC MUTATIONS THROUGH MULTISCALE AND MULTIOMIC ANALYSIS OF INDIVIDUAL TUMORS Schupp, P., Shelton, S., Brody, D., Eliscu, R., Johnson, B., Mazor, T., Kelley, K., Potts, M., McDermott, M., Huang, E., Lim, D., Pieper, R., Berger, M., Costello, J., Phillips, J., Oldham, M. OXFORD UNIV PRESS INC. 2023

  View details for Web of Science ID 001115245400502

• Assembloid CRISPR screens reveal impact of disease genes in human neurodevelopment. Nature Meng, X., Yao, D., Imaizumi, K., Chen, X., Kelley, K. W., Reis, N., Thete, M. V., Arjun McKinney, A., Kulkarni, S., Panagiotakos, G., Bassik, M. C., Pașca, S. P. 2023

  Abstract

  The assembly of cortical circuits involves the generation and migration of interneurons from the ventral to the dorsal forebrain1-3, which has been challenging to study at inaccessible stages of late gestation and early postnatal human development4. Autism spectrum disorder and other neurodevelopmental disorders (NDDs) have been associated with abnormal cortical interneuron development5, but which of these NDD genes affect interneuron generation and migration, and how they mediate these effects remains unknown. We previously developed a platform to study interneuron development and migration in subpallial organoids and forebrain assembloids6. Here we integrate assembloids with CRISPR screening to investigate the involvement of 425 NDD genes in human interneuron development. The first screen aimed at interneuron generation revealed 13 candidate genes, including CSDE1 and SMAD4. We subsequently conducted an interneuron migration screen in more than 1,000 forebrain assembloids that identified 33 candidate genes, including cytoskeleton-related genes and the endoplasmic reticulum-related gene LNPK. We discovered that, during interneuron migration, the endoplasmic reticulum is displaced along the leading neuronal branch before nuclear translocation. LNPK deletion interfered with this endoplasmic reticulum displacement and resulted in abnormal migration. These results highlight the power of this CRISPR-assembloid platform to systematically map NDD genes onto human development and reveal disease mechanisms.

  View details for DOI 10.1038/s41586-023-06564-w

  View details for PubMedID 37758944

  View details for PubMedCentralID 4349583

• Scrutinizing disease states and regulation in human microglia. Nature genetics Kelley, K. W., Pașca, S. P. 2021

  View details for DOI 10.1038/s41588-021-00826-x

  View details for PubMedID 34083790

• Neurotoxic microglia promote TDP-43 proteinopathy in progranulin deficiency. Nature Zhang, J., Velmeshev, D., Hashimoto, K., Huang, Y. H., Hofmann, J. W., Shi, X., Chen, J., Leidal, A. M., Dishart, J. G., Cahill, M. K., Kelley, K. W., Liddelow, S. A., Seeley, W. W., Miller, B. L., Walther, T. C., Farese, R. V., Taylor, J. P., Ullian, E. M., Huang, B., Debnath, J., Wittmann, T., Kriegstein, A. R., Huang, E. J. 2020; 588 (7838): 459-465

  Abstract

  Aberrant aggregation of the RNA-binding protein TDP-43 in neurons is a hallmark of frontotemporal lobar degeneration caused by haploinsufficiency in the gene encoding progranulin1,2. However, the mechanism leading to TDP-43 proteinopathy remains unclear. Here we use single-nucleus RNA sequencing to show that progranulin deficiency promotes microglial transition from a homeostatic to a disease-specific state that causes endolysosomal dysfunction and neurodegeneration in mice. These defects persist even when Grn-/- microglia are cultured ex vivo. In addition, single-nucleus RNA sequencing reveals selective loss of excitatory neurons at disease end-stage, which is characterized by prominent nuclear and cytoplasmic TDP-43 granules and nuclear pore defects. Remarkably, conditioned media from Grn-/- microglia are sufficient to promote TDP-43 granule formation, nuclear pore defects and cell death in excitatory neurons via the complement activation pathway. Consistent with these results, deletion of the genes encoding C1qa and C3 mitigates microglial toxicity and rescues TDP-43 proteinopathy and neurodegeneration. These results uncover previously unappreciated contributions of chronic microglial toxicity to TDP-43 proteinopathy during neurodegeneration.

  View details for DOI 10.1038/s41586-020-2709-7

  View details for PubMedID 32866962

  View details for PubMedCentralID PMC7746606

• Generation of Functional Human 3D Cortico-Motor Assembloids. Cell Andersen, J. n., Revah, O. n., Miura, Y. n., Thom, N. n., Amin, N. D., Kelley, K. W., Singh, M. n., Chen, X. n., Thete, M. V., Walczak, E. M., Vogel, H. n., Fan, H. C., Paşca, S. P. 2020

  Abstract

  Neurons in the cerebral cortex connect through descending pathways to hindbrain and spinal cord to activate muscle and generate movement. Although components of this pathway have been previously generated and studied in vitro, the assembly of this multi-synaptic circuit has not yet been achieved with human cells. Here, we derive organoids resembling the cerebral cortex or the hindbrain/spinal cord and assemble them with human skeletal muscle spheroids to generate 3D cortico-motor assembloids. Using rabies tracing, calcium imaging, and patch-clamp recordings, we show that corticofugal neurons project and connect with spinal spheroids, while spinal-derived motor neurons connect with muscle. Glutamate uncaging or optogenetic stimulation of cortical spheroids triggers robust contraction of 3D muscle, and assembloids are morphologically and functionally intact for up to 10 weeks post-fusion. Together, this system highlights the remarkable self-assembly capacity of 3D cultures to form functional circuits that could be used to understand development and disease.

  View details for DOI 10.1016/j.cell.2020.11.017

  View details for PubMedID 33333020

• Does Adult Neurogenesis Persist in the Human Hippocampus? Cell stem cell Paredes, M. F., Sorrells, S. F., Cebrian-Silla, A., Sandoval, K., Qi, D., Kelley, K. W., James, D., Mayer, S., Chang, J., Auguste, K. I., Chang, E. F., Gutierrez Martin, A. J., Kriegstein, A. R., Mathern, G. W., Oldham, M. C., Huang, E. J., Garcia-Verdugo, J. M., Yang, Z., Alvarez-Buylla, A. 2018; 23 (6): 780-781

  View details for DOI 10.1016/j.stem.2018.11.006

  View details for PubMedID 30526879

  View details for PubMedCentralID PMC6800191

• Oligodendrocyte-encoded Kir4.1 function is required for axonal integrity. eLife Schirmer, L., Möbius, W., Zhao, C., Cruz-Herranz, A., Ben Haim, L., Cordano, C., Shiow, L. R., Kelley, K. W., Sadowski, B., Timmons, G., Pröbstel, A. K., Wright, J. N., Sin, J. H., Devereux, M., Morrison, D. E., Chang, S. M., Sabeur, K., Green, A. J., Nave, K. A., Franklin, R. J., Rowitch, D. H. 2018; 7

  Abstract

  Glial support is critical for normal axon function and can become dysregulated in white matter (WM) disease. In humans, loss-of-function mutations of KCNJ10, which encodes the inward-rectifying potassium channel KIR4.1, causes seizures and progressive neurological decline. We investigated Kir4.1 functions in oligodendrocytes (OLs) during development, adulthood and after WM injury. We observed that Kir4.1 channels localized to perinodal areas and the inner myelin tongue, suggesting roles in juxta-axonal K+ removal. Conditional knockout (cKO) of OL-Kcnj10 resulted in late onset mitochondrial damage and axonal degeneration. This was accompanied by neuronal loss and neuro-axonal dysfunction in adult OL-Kcnj10 cKO mice as shown by delayed visual evoked potentials, inner retinal thinning and progressive motor deficits. Axon pathologies in OL-Kcnj10 cKO were exacerbated after WM injury in the spinal cord. Our findings point towards a critical role of OL-Kir4.1 for long-term maintenance of axonal function and integrity during adulthood and after WM injury.

  View details for DOI 10.7554/eLife.36428

  View details for PubMedID 30204081

  View details for PubMedCentralID PMC6167053

• Astrocyte-derived interleukin-33 promotes microglial synapse engulfment and neural circuit development SCIENCE Vainchtein, I. D., Chin, G., Cho, F. S., Kelley, K. W., Miller, J. G., Chien, E. C., Liddelow, S. A., Nguyen, P. T., Nakao-Inoue, H., Dorman, L. C., Akil, O., Joshita, S., Barres, B. A., Paz, J. T., Molofsky, A. B., Molofsky, A. V. 2018; 359 (6381): 1269–73

  Abstract

  Neuronal synapse formation and remodeling are essential to central nervous system (CNS) development and are dysfunctional in neurodevelopmental diseases. Innate immune signals regulate tissue remodeling in the periphery, but how this affects CNS synapses is largely unknown. Here, we show that the interleukin-1 family cytokine interleukin-33 (IL-33) is produced by developing astrocytes and is developmentally required for normal synapse numbers and neural circuit function in the spinal cord and thalamus. We find that IL-33 signals primarily to microglia under physiologic conditions, that it promotes microglial synapse engulfment, and that it can drive microglial-dependent synapse depletion in vivo. These data reveal a cytokine-mediated mechanism required to maintain synapse homeostasis during CNS development.

  View details for PubMedID 29420261

• Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults NATURE Sorrells, S. F., Paredes, M. F., Ebrian-Silla, A. C., Sandoval, K., Qi, D., Kelley, K. W., James, D., Mayer, S., Chang, J., Auguste, K. I., Hang, E. C., Gutierrez, A. J., Kriegstein, A. R., Mathern, G. W., Oldham, M. C., Huang, E. J., Manuel Garcia-Verdugo, J., Yang, Z., Alvarez-Buylla, A. 2018; 555 (7696): 377-+

  Abstract

  New neurons continue to be generated in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus. This process has been linked to learning and memory, stress and exercise, and is thought to be altered in neurological disease. In humans, some studies have suggested that hundreds of new neurons are added to the adult dentate gyrus every day, whereas other studies find many fewer putative new neurons. Despite these discrepancies, it is generally believed that the adult human hippocampus continues to generate new neurons. Here we show that a defined population of progenitor cells does not coalesce in the subgranular zone during human fetal or postnatal development. We also find that the number of proliferating progenitors and young neurons in the dentate gyrus declines sharply during the first year of life and only a few isolated young neurons are observed by 7 and 13 years of age. In adult patients with epilepsy and healthy adults (18-77 years; n = 17 post-mortem samples from controls; n = 12 surgical resection samples from patients with epilepsy), young neurons were not detected in the dentate gyrus. In the monkey (Macaca mulatta) hippocampus, proliferation of neurons in the subgranular zone was found in early postnatal life, but this diminished during juvenile development as neurogenesis decreased. We conclude that recruitment of young neurons to the primate hippocampus decreases rapidly during the first years of life, and that neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans. The early decline in hippocampal neurogenesis raises questions about how the function of the dentate gyrus differs between humans and other species in which adult hippocampal neurogenesis is preserved.

  View details for DOI 10.1038/nature25975

  View details for Web of Science ID 000427477100038

  View details for PubMedID 29513649

  View details for PubMedCentralID PMC6179355

• Secretagogin is Expressed by Developing Neocortical GABAergic Neurons in Humans but not Mice and Increases Neurite Arbor Size and Complexity. Cerebral cortex (New York, N.Y. : 1991) Raju, C. S., Spatazza, J., Stanco, A., Larimer, P., Sorrells, S. F., Kelley, K. W., Nicholas, C. R., Paredes, M. F., Lui, J. H., Hasenstaub, A. R., Kriegstein, A. R., Alvarez-Buylla, A., Rubenstein, J. L., Oldham, M. C. 2017: 1-13

  Abstract

  The neocortex of primates, including humans, contains more abundant and diverse inhibitory neurons compared with rodents, but the molecular foundations of these observations are unknown. Through integrative gene coexpression analysis, we determined a consensus transcriptional profile of GABAergic neurons in mid-gestation human neocortex. By comparing this profile to genes expressed in GABAergic neurons purified from neonatal mouse neocortex, we identified conserved and distinct aspects of gene expression in these cells between the species. We show here that the calcium-binding protein secretagogin (SCGN) is robustly expressed by neocortical GABAergic neurons derived from caudal ganglionic eminences (CGE) and lateral ganglionic eminences during human but not mouse brain development. Through electrophysiological and morphometric analyses, we examined the effects of SCGN expression on GABAergic neuron function and form. Forced expression of SCGN in CGE-derived mouse GABAergic neurons significantly increased total neurite length and arbor complexity following transplantation into mouse neocortex, revealing a molecular pathway that contributes to morphological differences in these cells between rodents and primates.

  View details for DOI 10.1093/cercor/bhx101

  View details for PubMedID 28449024

• Progranulin Deficiency Promotes Circuit-Specific Synaptic Pruning by Microglia via Complement Activation CELL Lui, H., Zhang, J., Makinson, S. R., Cahill, M. K., Kelley, K. W., Huang, H., Shang, Y., Oldham, M. C., Martens, L. H., Gao, F., Coppola, G., Sloan, S. A., Hsieh, C. L., Kim, C. C., Bigio, E. H., Weintraub, S., Mesulam, M., Rademakers, R., Mackenzie, I. R., Seeley, W. W., Karydas, A., Miller, B. L., Borroni, B., Ghidoni, R., Farese, R. V., Paz, J. T., Barres, B. A., Huang, E. J. 2016; 165 (4): 921-935

  Abstract

  Microglia maintain homeostasis in the brain, but whether aberrant microglial activation can cause neurodegeneration remains controversial. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive upregulation of lysosomal and innate immunity genes, increased complement production, and enhanced synaptic pruning in microglia. During aging, Grn(-/-) mice show profound microglia infiltration and preferential elimination of inhibitory synapses in the ventral thalamus, which lead to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors. Remarkably, deleting C1qa gene significantly reduces synaptic pruning by Grn(-/-) microglia and mitigates neurodegeneration, behavioral phenotypes, and premature mortality in Grn(-/-) mice. Together, our results uncover a previously unrecognized role of progranulin in suppressing aberrant microglia activation during aging. These results represent an important conceptual advance that complement activation and microglia-mediated synaptic pruning are major drivers, rather than consequences, of neurodegeneration caused by progranulin deficiency.

  View details for DOI 10.1016/j.cell.2016.04.001

  View details for Web of Science ID 000375800300019

  View details for PubMedID 27114033

  View details for PubMedCentralID PMC4860138

• Astrocytes: The Final Frontier…. Neuron Kelley, K. W., Rowitch, D. H. 2016; 89 (1): 1-2

  Abstract

  In this issue of Neuron, Zhang et al. (2016) develop a novel approach to generate populations of human astrocytes to uncover their uniquely human traits.

  View details for DOI 10.1016/j.neuron.2015.12.030

  View details for PubMedID 26748083

• Transcriptional architecture of the human brain. Nature neuroscience Kelley, K. W., Oldham, M. C. 2015; 18 (12): 1699-701

  View details for DOI 10.1038/nn.4178

  View details for PubMedID 26605877

• Distinct and separable roles for EZH2 in neurogenic astroglia. eLife Hwang, W. W., Salinas, R. D., Siu, J. J., Kelley, K. W., Delgado, R. N., Paredes, M. F., Alvarez-Buylla, A., Oldham, M. C., Lim, D. A. 2014; 3: e02439

  Abstract

  The epigenetic mechanisms that enable specialized astrocytes to retain neurogenic competence throughout adult life are still poorly understood. Here we show that astrocytes that serve as neural stem cells (NSCs) in the adult mouse subventricular zone (SVZ) express the histone methyltransferase EZH2. This Polycomb repressive factor is required for neurogenesis independent of its role in SVZ NSC proliferation, as Ink4a/Arf-deficiency in Ezh2-deleted SVZ NSCs rescues cell proliferation, but neurogenesis remains defective. Olig2 is a direct target of EZH2, and repression of this bHLH transcription factor is critical for neuronal differentiation. Furthermore, Ezh2 prevents the inappropriate activation of genes associated with non-SVZ neuronal subtypes. In the human brain, SVZ cells including local astroglia also express EZH2, correlating with postnatal neurogenesis. Thus, EZH2 is an epigenetic regulator that distinguishes neurogenic SVZ astrocytes, orchestrating distinct and separable aspects of adult stem cell biology, which has important implications for regenerative medicine and oncogenesis.DOI: http://dx.doi.org/10.7554/eLife.02439.001.

  View details for DOI 10.7554/eLife.02439

  View details for PubMedID 24867641

  View details for PubMedCentralID PMC4032491

• Astrocyte-encoded positional cues maintain sensorimotor circuit integrity. Nature Molofsky, A. V., Kelley, K. W., Tsai, H. H., Redmond, S. A., Chang, S. M., Madireddy, L., Chan, J. R., Baranzini, S. E., Ullian, E. M., Rowitch, D. H. 2014; 509 (7499): 189-94

  Abstract

  Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help to refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded semaphorin 3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a leads to dysregulated α-motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α- but not of adjacent γ-motor neurons. In addition, a subset of TrkA(+) sensory afferents projects to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement.

  View details for DOI 10.1038/nature13161

  View details for PubMedID 24776795

  View details for PubMedCentralID PMC4057936

• Expression profiling of Aldh1l1-precursors in the developing spinal cord reveals glial lineage-specific genes and direct Sox9-Nfe2l1 interactions. Glia Molofsky, A. V., Glasgow, S. M., Chaboub, L. S., Tsai, H. H., Murnen, A. T., Kelley, K. W., Fancy, S. P., Yuen, T. J., Madireddy, L., Baranzini, S., Deneen, B., Rowitch, D. H., Oldham, M. C. 2013; 61 (9): 1518-32

  Abstract

  Developmental regulation of gliogenesis in the mammalian CNS is incompletely understood, in part due to a limited repertoire of lineage-specific genes. We used Aldh1l1-GFP as a marker for gliogenic radial glia and later-stage precursors of developing astrocytes and performed gene expression profiling of these cells. We then used this dataset to identify candidate transcription factors that may serve as glial markers or regulators of glial fate. Our analysis generated a database of developmental stage-related markers of Aldh1l1+ cells between murine embryonic day 13.5-18.5. Using these data we identify the bZIP transcription factor Nfe2l1 and demonstrate that it promotes glial fate under direct Sox9 regulatory control. Thus, this dataset represents a resource for identifying novel regulators of glial development.

  View details for DOI 10.1002/glia.22538

  View details for PubMedID 23840004

  View details for PubMedCentralID PMC3909648

• Polymorph-specific kinetics and thermodynamics of β-amyloid fibril growth. Journal of the American Chemical Society Qiang, W., Kelley, K., Tycko, R. 2013; 135 (18): 6860-71

  Abstract

  Amyloid fibrils formed by the 40-residue β-amyloid peptide (Aβ(1-40)) are highly polymorphic, with molecular structures that depend on the details of growth conditions. Underlying differences in physical properties are not well understood. Here, we investigate differences in growth kinetics and thermodynamic stabilities of two Aβ(1-40) fibril polymorphs for which detailed structural models are available from solid-state nuclear magnetic resonance (NMR) studies. Rates of seeded fibril elongation in the presence of excess soluble Aβ(1-40) and shrinkage in the absence of soluble Aβ(1-40) are determined with atomic force microscopy (AFM). From these rates, we derive polymorph-specific values for the soluble Aβ(1-40) concentration at quasi-equilibrium, from which relative stabilities can be derived. The AFM results are supported by direct measurements by ultraviolet absorbance, using a novel dialysis system to establish quasi-equilibrium. At 24 °C, the two polymorphs have significantly different elongation and shrinkage kinetics but similar thermodynamic stabilities. At 37 °C, differences in kinetics are reduced, and thermodynamic stabilities are increased significantly. Fibril length distributions in AFM images provide support for an intermittent growth model, in which fibrils switch randomly between an "on" state (capable of elongation) and an "off" state (incapable of elongation). We also monitor interconversion between polymorphs at 24 °C by solid-state NMR, showing that the two-fold symmetric "agitated" (A) polymorph is more stable than the three-fold symmetric "quiescent" (Q) polymorph. Finally, we show that the two polymorphs have significantly different rates of fragmentation in the presence of shear forces, a difference that helps explain the observed predominance of the A structure when fibrils are grown in agitated solutions.

  View details for DOI 10.1021/ja311963f

  View details for PubMedID 23627695

  View details for PubMedCentralID PMC3686096