Estudiantes actuales con becas activas
Beca F31 del NIH NRSA de Jessie Larios Valencia para un proyecto titulado "El papel de la desdiferenciación en el cáncer de mama de tipo basal" (patrocinador: Wenjun Guo, Cell Biology)
Beca F31 del NIH NRSA de Eric Sosa para un proyecto titulado "Definición de las funciones reguladoras de los genes de las variantes no codificantes en la patogénesis del autismo" (patrocinador: John Greally, Genetics)
Beca Tram Nguyen NIH NRSA F30 para un proyecto titulado "Función de recompensa en adolescentes con depresión y consumo de cannabis" (copatrocinadores: Vilma Gabbay y Benjamin Ely, PCI-Neuroscience & Psychiatry)
Beca F30 del NIH NRSA de Gabriel Bedard para un proyecto titulado "Diseño racional de terapias contra el cáncer que aprovechen la letalidad sintética del metabolismo de la metionina y las metiltransferasas de arginina" (patrocinador: Vern Schramm, BioquÃÂmica)
Beca Matanel Yheskel NIH NRSA F31 para un proyecto titulado "Consecuencias epigenéticas y transcripcionales de las mutaciones asociadas a la discapacidad intelectual en la histona lisina desmetilasa KDM5" (patrocinador: Julie Secombe, Genética)
Beca F30 del NIH NRSA de Andrea Bae para un proyecto titulado "El papel de las oscilaciones cerebrales en las redes del mesencéfalo y el prosencéfalo que respaldan la selección de estÃÂmulos en la vÃÂa de localización del sonido de las lechuzas" (patrocinador: José Luis Peña, Neurociencia)
Beca F30 del NIH NRSA de Jacob Stauber para un proyecto titulado "Comprensión de la dinámica de la evolución de las células madre de la hematopoyesis clonal del donante en el trasplante alogénico de células hematopoyéticas a nivel de célula única" (copatrocinadores: John Greally y Ulrich Steidl, Genética y BiologÃÂa Celular)
Beca Ian MacArthur NIH NRSA F30 para un proyecto titulado "Regulación epigenética de la biologÃÂa de las células madre neuronales por las dioxigenasas del ADN Tet" (patrocinador: Meelad Dawlaty, Genetics)
Beca F31 del NIH NRSA de Leti Nunez para un proyecto titulado "Determinación del efecto de la fosforilación de la proteÃÂna de unión al ARN en el destino del ARNm" (patrocinador: Robert Singer, AnatomÃÂa y BiologÃÂa Estructural)
Beca F30 del NIH NRSA de Chris Nishimura para un proyecto titulado "Disección mecanicista y focalización terapéutica de B7x en el cáncer" (patrocinador: XingXing Zang, MicrobiologÃÂa e InmunologÃÂa)
Beca F30 del NIH NRSA de John "Jack" Barbaro para un proyecto titulado "La metanfetamina y la terapia antirretroviral afectan las funciones de los macrófagos y la macroautofagia: implicaciones para la neuropatogénesis del VIH" (patrocinador: Joan Berman, PatologÃÂa)
Ryan Graff NIH NRSA F30 Fellowship for a project entitled "Platelet PI3Kβ regulation of metastasis" (Sponsor, Jonathan Backer and Anne Bresnick, Molecular Pharmacology)
Beca F31 del NIH NRSA de Henrietta Bains para un proyecto titulado "¿Cómo detecta mTOR los lÃÂpidos in vivo ?" (Patrocinador: Rajat Singh, BiologÃÂa molecular y del desarrollo)
Beca Julio Flores NIH NRSA F31 para un proyecto titulado "Regulación epigenética de células madre y desarrollo por la ADN dioxigenasa Te2" (Patrocinador, Meelad Dawlaty, Genetics)
Beca F30 del NIH NRSA de Daniel Borger para un proyecto titulado "Desarrollo de una nueva plataforma ex vivo para sustentar células hematopoyéticas y caracterizar el nicho de células madre" (patrocinador: Paul Frenette, biologÃÂa celular)
Beca NIH NRSA F30 de Ryan Malonis para un proyecto titulado "Descubrimiento y caracterización de anticuerpos monoclonales humanos dirigidos a múltiples alfavirus artritogénicos" (patrocinador: Jon Lai, BioquÃÂmica)
Beca F31 del NIH NRSA de Bianca Ulloa para un proyecto titulado "Descifrando el desarrollo de la autorrenovación y diferenciación de células madre y progenitoras hematopoyéticas" (Patrocinador: Teresa Bowman, BiologÃÂa del Desarrollo y Molecular)
Beca F31 del Instituto Nacional de Salud y Servicios Humanos de Estados Unidos (NIH) de Taylor Thompson para un proyecto titulado "Influencias de un disruptor endocrino en la regulación de la transcripción y la diferenciación celular" (patrocinador: John Greally, Genetics)
Beca F31 del NIH NRSA de Michelle Gulfo para un proyecto titulado "Evaluación de la modulación dopaminérgica de un circuito asociativo dentro del giro dentado" (patrocinador: Pablo Castillo, Neurociencia)
Beca Hayden Hatch NIH NRSA F31 para un proyecto titulado "Regulación transcripcional, desarrollo neuronal y función del cuerpo en forma de hongo en un modelo de discapacidad intelectual de Drosophila" (Co-patrocinadores: Julie Secombe y Nicholas Baker, Neurociencia/Genética)
Estudiantes actuales con becas completadas
Beca Meera Trivedi NIH NRSA F31 para un proyecto titulado "Caracterización de nuevas regulaciones de mosaico dendrÃÂtico en C. elegans " (patrocinador: Hannes Buelow, Neurociencia)
Resúmenes de proyectos recientes
Eric Sosa - ABSTRACT: In this Predoctoral Fellowship proposal, I will be trained for a future as a physician-scientist with my own independent research program at the interface of genomics, computational
biology, and neuroscience. During my MD/PhD training, I will be co-mentored by two physician-scientists, Drs. John Greally (Medical Genomics) and Pablo Castillo (Neurology), addressing a question that is timely with
the imminent widespread use of whole genome sequencing (WGS) in clinical diagnostics – how do we interpret variants in the noncoding majority of the human genome when a patient presents with a medical problem? I will
focus on autism, as a condition that represents a substantial proportion of patients seen by medical genetics services, for which there is extensive WGS information from thousands of families. Despite this wealth of
research sequencing, only a small minority of individuals with autism receive a positive outcome of diagnostic exome or WGS. I propose that the currently limited diagnostic success rates are mostly due to our inability
to interpret pathogenic variants in the non-coding majority of the genome of these patients. By improving our insights into non-coding variants, we will be able to offer diagnostic information to many more families
seeking answers than currently. My strategy is to focus on de novo variants (DNVs) in offspring with autism born to unaffected parents. My hypothesis is that DNVs can be pathogenic when they occur in the cis-regulatory
regions of cell types mediating autism. The project is therefore based on a computational genomics foundation, using WGS and DNV calls from large datasets from thousands of families who have a member with autism. In
my preliminary data, I show that DNVs in individuals with autism are enriched at cis-regulatory loci in glial and neuronal cells in particular, and at genes known to be causative for autism. In my project, I will test
these associations more rigorously, and will define a high-confidence set of DNVs for functional testing. Two types of functional testing will be performed. One will test whether the DNVs alter molecular genomic properties,
including chromatin accessibility and gene expression. The second will test the physiological properties of the cells. To generate the appropriate cells for testing, I plan to use induced pluripotent stem cells (iPSCs)
that are in vitro differentiated to GABAergic neurons and astrocytes. By performing CRISPR-mediated genomic editing in the iPSCs, I can generate cells with the candidate pathogenic DNVs, and test whether they have effects
on cellular properties like dendritogenesis, synaptogenesis, and electrophysiology, increasing the confidence that these DNVs have pathogenic effects. I will have the privilege of getting training in sophisticated computational,
stem cell and neuroscience techniques, under the guidance of two leaders in their fields, as part of a comprehensive training plan that will equip me to become the independent physician-scientist I aspire to be in my
career.
Tram Nguyen - ABSTRACT: Adolescent depression and cannabis use are concurrent major public health concerns, and this comorbidity has been associated with long-term cognitive and behavioral consequences.
However, there has been sparse research in this area, as most neuroimaging studies in adolescent depression exclude cannabis users. We seek to address this gap based on converging evidence that: 1) Reward dysfunction
contributes to maintenance and progression of depression in adolescents; 2) Reward dysfunction is a heterogenous construct involving deficits in diverse cognitive processes, including reward anticipation, attainment,
and prediction error; 3) These deficits entail distinct neural mechanisms that can be studied by functional magnetic resonance imaging (fMRI); 4) The major psychoactive agent in cannabis, Δ9-tetrahydrocannabinol (THC),
exerts its effects through modulation of the cortico-striatal reward system; and 5) Cannabis use may result in temporary relief of mood and anxiety symptoms while inducing potentially deleterious long-term neural reward
alterations. We documented that anhedonia–a core symptom of depression reflecting reward deficits–was associated with worse depression outcomes, including chronicity and suicidality, in adolescents. Similarly, using
resting-state fMRI, we found that altered striatal intrinsic functional connectivity (iFC) with the prefrontal cortex was associated with anhedonia severity in depressed adolescents. Further, using the reward flanker
task (RFT), we found that adolescents with diverse mood and anxiety symptoms showed weaker striatal activation during reward anticipation than healthy controls, while stronger activation in the anterior cingulate cortex
predicted worse higher levels of anhedonia at two-year follow-up. We therefore propose a 2×2 cross-sectional study to test the overall hypothesis that comorbid cannabis use in adolescent depression is associated with
more severe neural reward deficits and clinical symptoms. Participants will comprise 30 depressed cannabis users, 30 depressed cannabis non-users, 30 non-depressed cannabis users, and 30 healthy controls, all ages 14-18
(Tanner stage ≥ 4) and psychotropic-medication-free. Using resting-state and RFT task fMRI, we predict that comorbid cannabis use and depression will be associated with more pronounced deficits in reward anticipation
(Aim 1) and alterations in cortico-striatal iFC (Aim 2) than depression alone. Further analyses (Exploratory Aims) will assess the relationships between cannabis use frequency and activation during reward anticipation,
cortico-striatal iFC, and symptom severity. Public Health Relevance: This proposal aims to address a critical and growing public health concern that to date has received minimal research attention while providing a
rigorous framework for predoctoral training in both clinical research and advanced neuroimaging techniques. Findings from this work will expand the limited understanding regarding the impact of cannabis on reward dysfunction
in youth, with potential to inform both clinical practice and government policies on cannabis use.
Gabriel Bedard - ABSTRACT: Methionine adenosyltransferase 2 alpha (MAT2A) and protein arginine methyltransferase 5 (PRMT5) are cancer targets that are synthetically lethal with MTAP deletions and have several
drug candidates in clinical trials targeting MTAP-/- cancers. MTAP is deleted in ~15% of human cancers and encodes the metabolic enzyme 5’-methylthioadenosine phosphorylase, the sole enzyme in humans responsible for
recycling of methylthioadenosine (MTA) to methionine. MAT2A synthesizes S-adenosyl methionine (SAM), the methyl donor substrate for methyltransferase reactions. PRMT5 utilizes SAM as a substrate and is inhibited by
MTA, and MTAP-/- cells in culture demonstrate elevated MTA levels. In vivo observations of glioblastoma tumors suggest however, that MTAP-/- does not always lead to increased tumoral MTA levels due to MTA efflux into
matrix MTAP-competent cells. Additionally, MTAP deletions are a rare (~2%) occurrence in colorectal cancers (CRCs), precluding MAT2A and PRMT5 inhibitors’ use for most CRCs. The Schramm laboratory has previously solved
the transition state (TS) structure of MTAP and synthesized a potent small molecule inhibitor methylthio-DADMe-immucillin-A (MTDIA) that recapitulates the in vitro effects of MTA accumulation within tissues. MTDIA has
been shown to inhibit tumor growth in several cancer models, including CRC, and is linked to a decrease in PRMT5 activity through elevation of MTA levels. We propose that MTDIA be used in combination with MAT2A inhibitor
AG-270, currently in Phase I clinical trials, to harness their synthetic lethality by targeting PRMT5. We will test the safety, target engagement, and anti-cancer efficacy of MTDIA in combination with AG-270 in ApcMin/+
and CRC patient-derived xenograft (PDX) mice. To determine mechanisms of anti-cancer effects, we will probe the upstream and downstream effects related to PRMT5 activity. We will perform tumor metabolomic quantification
of relevant metabolites and histone and protein-arginine methylation characterization using immunohistochemistry and proteomic techniques. We will also profile the gene expression changes using single-cell RNA sequencing
to determine how combination therapy alters tumor architecture and growth. Finally, we will solve the transition state structure of PRMT5 with the goal of laying the foundations for development of novel transition state
analogue inhibitors. This work will expand upon the use of MAT2A and PRMT5 inhibitors beyond the ~15% of MTAP-deleted cancers and provide avenues for MTDIA to be used in clinical trials.
Ian MacArthur - ABSTRACT: The ten-eleven translocation family (TET1/2/3) of enzymes are epigenetic regulators of gene expression that are highly expressed in neural stem cells (NSCs) and during mammalian
nervous system development. TET enzymes are dioxygenases that promote active and passive DNA demethylation by converting 5-methylcytosine (5mC) into 5-hydroxymethycytosine (5hmC) and higher-order oxidized derivatives.
In addition to its role as a demethylation intermediate, 5hmC can function as a stable epigenetic mark and is highly enriched and dynamic in the developing nervous system. TET enzymes and 5hmC dysregulation have been
implicated in human neurodevelopmental syndromes, intellectual disability, craniofacial abnormalities, and neurodegeneration. These observations suggest a critical role for TET enzymes in the developing nervous system
and has led to interest in their roles in the biology of NSCs. However, the functions of TET enzymes in NSCs and neurodevelopment remain poorly understood. Preliminary data from our lab demonstrates that Tet tripleknockout
NSCs (T123–/–) derived from embryonic stem cells exhibit severe defects in self-renewal, multipotency, and expression of neurodevelopmental genes. We therefore hypothesize that TET enzymes have essential functions in
epigenetic regulation of gene expression programs critical for NSC maintenance and multipotency and in embryonic neurodevelopment. To test this hypothesis, we have derived embryonic forebrain NSC lines containing floxed
alleles of Tet1/2/3 and a tamoxifen-inducible Cre recombinase transgene expressed from the constitutive Rosa26 locus (T123F/F; +/R26-CreER) for conditional, combined deletion of all three Tet genes. We have also established
a colony of Tet1/2/3 triple-floxed mice expressing a tamoxifen-inducible Cre recombinase transgene under control of the neural-specific Nestin promoter (T123F/F; +/Nestin-CreERT2). Using these models, we will (1) define
the role of TET enzymes in the maintenance and multipotency of NSCs , (2) establish the requirement of TETs in embryonic neurodevelopment, and (3) identify TET-mediated epigenetic and transcriptional regulatory mechanisms
in NSCs. Findings from these studies will define novel roles played by TET enzymes in NSC biology and neurodevelopment, provide insights into how dysregulation of TETs contribute to human neurodevelopmental disorders,
and identify novel targets for therapy.
Chris Nishimura - ABSTRACT: Immune checkpoints are proteins that regulate the body’s immune system via inhibition of immune cells. In diseases such as cancer, these same pathways may be commandeered in
order to inappropriately inhibit immune responses. One approach to overcome this excessive inhibition and restore normal immune function is to physically block these inhibitory proteins using monoclonal antibodies (mAbs),
a strategy known as immune checkpoint blockade. Our lab discovered the protein B7x (VTCN1/B7S1/B7-H4), an immune checkpoint whose regulation and mechanism of action are still being elucidated. B7x is expressed on a
wide variety of cancers and is associated with poor clinical outcomes. It has been shown to inhibit effector T cell functions such as cytokine production and proliferation, and promotes T cell exhaustion; it has also
been associated with tumor infiltration of immunosuppressive cell populations such as myeloid derived suppressor cells (MDSCs). Intriguingly, it is not typically co-expressed with the well-studied immune checkpoint
PD-L1, and blocking B7x using anti-B7x mAbs improves anti-tumor responses and survival in mouse models. This suggests that B7x holds a non-overlapping but key role in cancer immune evasion. For these reasons I hypothesize
that B7x mediates immune evasion through inhibiting effector cell functions while simultaneously promoting immunosuppressive cells and is therefore a promising target for cancer immunotherapy. Thus, we propose the following
two aims: 1) Examine the mechanisms that regulate B7x expression and its role on MDSCs; and 2) Develop and characterize a new anti-B7x immunotherapy. In aim 1 I will examine the how hypoxia and other tumor microenvironment-associated
cytokines regulate B7x expression. In addition, I will explore how B7x affects the immunosuppressive MDSC cell population generation and survival. In aim 2 I will test the anti-tumor efficacy of newly generated anti-B7x
mAb-based immune checkpoint blockade in vivo using metastasis and spontaneous models of lung cancer. We will also characterize how this new immunotherapy alters T cell phenotypes using flow cytometry and single-cell
RNA sequencing. Finally, we will explore if combining our anti-B7x mAb with anti-TIM3 and anti-PD1 mAbs confers superior anti-tumor efficacy than anti-B7x monotherapy in vivo. Together, these studies will allow us to
broadly explore the role of B7x in tumorigenesis and therapeutic potential of anti-B7x immunotherapy, and combined with a personalized training plan and supportive research environment at Einstein, cultivate the skills
required of a physician-scientist.
Ryan Graff - ABSTRACT: Metastasis is the primary cause of morbidity and mortality among patients with solid tumors. Platelets interact with tumor cells upon their entry into the vasculature and promote
the metastatic spread of these cells by several mechanisms. Circulating tumor cells (CTCs) directly bind to and activate platelets resulting in the formation of platelet-fibrin complexes that envelope circulating tumor
cells and protect them from immune clearance. Adhesion to tumor cells also induces the release of platelet cytokines and other soluble factors that promote epithelial-mesenchymal transition in the tumor cells. Finally,
platelets promote the adhesion of CTCs to the endothelium, assisting in their extravasation at distant metastatic sites. Platelet activation, adhesion, and in vivo thrombus formation require the activity of the Class
IA PI 3-kinase PI3K. This isoform of PI3K produces the majority of PI(3,4,5)P3 in platelets, suggesting that PI3K has a unique role in classical platelet activation. However, the role of PI3K in platelet-mediated
cancer metastasis has yet to be defined. We propose that PI3K is required for platelet activation upon interaction with tumor cells. Aim 1 will test the role of platelet PI3K in platelet-stimulated tumor cell Matrigel
invasion, transendothelial migration, epithelial-mesenchymal transition, cell stemness, NFB activation, and platelet TGF secretion. We will also use RNAseq and antibody arrays to more broadly examine the role of PI3K
in platelet chemokine/cytokine release and in transcriptional responses by tumor cells. We will use both platelets from mice expressing mutant PI3K and human platelets pre-treated with the irreversible pan-PI3K inhibitor
wortmannin. Aim 2 will directly evaluate the role of platelet PI3K in cancer metastasis in wild type and whole-animal or platelet-specific mutant PI3K mice. Murine mammary carcinoma cells will be injected intravenously
to analyze in vivo tumor cell-platelet complex formation as well as tumor cell interactions with macrophages and other leukocytes. We will also test the role of PI3K in tumor cell-induced thrombocytopenia and experimental
metastasis. Isoform selective PI3K inhibitors were originally developed to be used as anti-thrombotic agents, as they prevent thrombotic occlusion of injured arteries without increasing bleeding. More recently these
inhibitors have also been explored as anti-cancer agents in the treatment of PTEN-deficient cancers. This proposal seeks to understand the potential for a broader application of these agents in cancer patients to inhibit
platelet activity and prevent metastasis in a variety of cancer types.
Henrietta Bains - ABSTRACT: Alterations in lipid metabolism determine metabolic disease and mortality in the aging population. Despite our understanding of regulation of lipid metabolism, how organisms
sense lipid remains unknown. It is conceivable that sensing of lipid will inform downstream decisions taken by the cell that modulate metabolism, proteostasis, stress response, and growth—each of which are dysregulated
with age. The mechanistic target of rapamycin (mTOR), is a serine/threonine kinase and amino acid sensor, that drives growth and proliferation. More recently, mTOR in cultured cells has been shown to be activated by
cholesterol and phosphatidic acid (PA) in absence of amino acids. Whether mTOR senses lipid in whole organisms is unclear. mTOR exists as two major complexes—mTORC1 and mTORC2. Activation of mTORC1 occurs at the lysosomal
surface in presence of amino acids and requires key regulatory proteins that stimulate its activity. By contrast, mTORC2 responds to growth factors to regulate cytoskeletal organization. Hyperactivation of mTORC1 (hereafter,
mTOR for simplicity) drives aging and age-related diseases in part by disrupting autophagy and promoting growth. Indeed, suppressing mTOR has been shown to increase lifespan in multiple organisms. However, how mTORC1
is hyperactivated with age remains unknown. It has been shown that there are quantitative and qualitative changes in membrane lipids with age including changes in lysosomal membrane lipids—the major site of mTOR activation.
Whether changes in lysosomal membrane lipids are mechanistically linked to mTOR hyperactivation remain unknown. Our preliminary data show that subjecting mice to an oral gavage of corn oil causes activation of mTOR
and its translocation to distinct cholesterol-rich microdomains (CRMs)/lipid rafts in lysosome membranes. Our preliminary data also show that immunoprecipitating mTOR from lysosome membranes from livers of oil-gavaged
mice reveal its binding to diacylglycerol. These data suggest that mTOR is a sensor of diacylglycerol, a membrane lipid. Since mTOR senses nutrients at lysosome membranes, I hypothesize that mTOR senses lipid at lysosomal
membranes, and that age-related changes in lysosomal membrane lipid composition lead to mTOR hyperactivation. To test our hypothesis, we present the following specific aims: Aim 1: To determine how mTOR senses lipid
at the lysosome surface. In Aim 1, diverse approaches will be used to characterize lipid-driven mTOR activation at lysosome membranes. By pulling down mTOR from lysosome membranes for lipidomic and proteomic analyses,
I will identify lipid species that bind to mTOR and its interacting partners. I will use an siRNA screen in vitro to silence each of the interacting partners, which will identify novel regulators of lipid-driven mTOR
signaling. Aim 2: To determine the mechanism of mTOR hyperactivation with age. In Aim 2, I will characterize the changes in lipid composition of lysosome membrane CRMs and expansion of lysosome CRMs with age. I will
determine whether alterations in membrane lipid composition with age correlate with increased mTOR activity. I will then determine whether inactivating the synthesis of specific membrane lipids, e.g., PA and DG, by
shRNAs against relevant biosynthetic enzymes in liver will dampen age-related mTOR hyperactivation. I will also determine whether targeting key interacting partners of mTOR in liver will dampen age-related hyperactivation
of mTOR signaling and reverse deleterious mTOR-dependent outcomes, i.e., blockage of autophagy and proteostasis failure.
Julio Flores- ABSTRACT: The Ten-eleven translocation (Tet1/2/3) family of enzymes are epigenetic regulators of gene expression important for stem cell biology and embryonic development. Tet enzymes are
dioxygenases that promote DNA demethylation by converting 5-methylcytosine (5mC) into 5-hydroxymethycytosine (5hmC) and higher oxidized derivatives. In addition to this enzymatic activity, Tet enzymes can bind chromatin
modifying complexes, to regulate genes in a presumably catalytic-independent manner. Tet2 is a key member of this family. It is highly expressed in embryonic stem cells (ESCs) and controls gene expression programs necessary
for stem cell lineage specification. Tet2 is also frequently mutated in hematological malignancies and has been implicated in neurodegenerative diseases. While the catalytic functions of Tet2 have been well studied,
its non-catalytic roles remain poorly defined. In this proposal, we seek to establish the significance of the catalytic dependent and independent functions of Tet2 in ESC gene regulation and lineage commitment. We hypothesize
that Tet2, in addition to regulating genes through its DNA demethylase activity, can also modulate genes in a non-catalytic fashion by recruiting histone modifiers to the chromatin, and this dual mode of gene regulation
is essential for proper ESC differentiation along the neural and hematopoietic lineages. To test this hypothesis, I have generated Tet2 catalytic mutant (Tet2m/m) and knock-out (Tet2–/–) ESCs, which I will use as a
platform to: (1) identify the catalytic and non-catalytic direct target genes of Tet2 in ESCs by integrating changes in gene expression with Tet2 genomic occupancy, (2) establish Tet2-mediated activating and repressing
mechanisms of gene regulation involving interactions with histone modifiers OGT and HDAC2, and finally (3) define the biological significance of Tet2 enzymatic and non-enzymatic functions in ESC differentiation and
lineage commitment along the neural and hematopoietic lineages. Findings from these experiments will elucidate novel epigenetic mechanisms of gene regulation in ESCs involving Tet2 catalytic and non-catalytic functions.
They will enhance our understanding of stem cell biology and development and can have implications in hematological malignancies where Tet2 is affected.
Daniel Borger- RESUMEN: Los métodos de cultivo actuales reducen la capacidad de las células madre hematopoyéticas (CMH) de injertarse con éxito en un huésped. Las tecnologÃÂas emergentes de edición genética, como CRISPR/Cas9, requieren tiempo en cultivo para permitir la corrección de los alelos causantes de enfermedades. Por lo tanto, existe la necesidad de desarrollar nuevos métodos de cultivo de CMH. El cocultivo de CMH con células de nicho de la médula ósea, como las células madre mesenquimales (CMM), es una posible solución a los problemas en el cultivo de CMH, ya que estas células proporcionan factores que respaldan a las CMH in vivo. Sin embargo, las CMM no se pueden mantener en cultivo durante perÃÂodos prolongados de tiempo y pierden con bastante rapidez la expresión de los factores de nicho. A través de una selección de factores de transcripción candidatos, nuestro laboratorio identificó 5 factores que, cuando se transducen juntos, restauran la expresión del factor de nicho y permiten un cultivo prolongado. Estos factores son el factor similar a Kruppel 7 ( Klf7 ), el factor estimulante de osteoclastos ( Ostf1 ), la proteÃÂna de unión a X-box ( XBP1 ), el factor regulador del interferón 3 ( Irf3 ) y el Irf7, que colectivamente denominamos factores KOXII. Las MSC transducidas con KOXII pudieron expandir las HSC funcionales tanto murinas como humanas en una medida mucho mayor que las MSC transducidas de forma simulada. Por lo tanto, estas células pueden ser útiles para expandir las HSC ex vivo para la corrección genética. Sin embargo, existen barreras regulatorias para la aplicación de células murinas en la terapéutica humana. El trabajo propuesto aquàse centrará en parte en el desarrollo y la caracterización de las MSC humanas transducidas con KOXII. Después de generar estas células, determinaré si los factores KOXII afectan la expresión de factores de nicho en las MSC humanas. También utilizaré la citometrÃÂa de flujo y el xenotrasplante de células madre para determinar si las MSC transducidas con KOXII son más eficaces para impulsar la expansión de las HSC que las MSC no modificadas. Por último, utilizando la edición genética basada en CRISPR/Cas9 de células madre hematopoyéticas derivadas de pacientes con anemia falciforme como modelo, determinaré si el cocultivo de células de pacientes con células madre hematopoyéticas transducidas con KOXII puede mejorar la eficiencia de la edición genética o aumentar el rendimiento de células editadas adecuadamente en comparación con los métodos de cultivo de células madre hematopoyéticas estándar actuales. En paralelo, utilizaré células madre hematopoyéticas murinas transducidas con KOXII para examinar más de cerca la señalización de nicho por parte de las células madre hematopoyéticas. Como estas células se pueden cultivar en cantidades relativamente grandes, son ideales para estudios proteómicos. En colaboración con el laboratorio de Jeroen Krijgsveld, examinaré el secretoma de estas células para identificar proteÃÂnas cuya secreción esté regulada positivamente por los factores KOXII. Utilizando ensayos tanto in vitro como in vivo, evaluaré el efecto de estos factores en el mantenimiento y la proliferación de las células madre hematopoyéticas, con el objetivo de identificar proteÃÂnas secretadas con funciones previamente no apreciadas en las interacciones de nicho entre células madre hematopoyéticas y células madre hematopoyéticas.
Ryan Malonis - ABSTRACT: Alphaviruses are enveloped, positive sense single-stranded RNA viruses, which include several important human pathogens. Arthritogenic alphaviruses are globally distributed, mosquito-transmitted
viruses that cause human rheumatic disease and include chikungunya virus (CHIKV) and Mayaro virus (MAYV). Symptomatic infection is characterized by fever, rash, myalgia, as well as both acute and chronic polyarthralgia
that can persist for months to years after infection. More severe manifestations of alphaviral disease – including hemorrhage, encephalopathy and mortality – have been reported. These viruses cause endemic disease as
well as large, sporadic epidemics worldwide. Currently, there are no approved vaccines or anti-viral therapies for the prevention or treatment of alphavirus infection; therefore, the development of new therapeutic strategies
targeting one or multiple arthritogenic alphaviruses is of substantial interest. A number of potently neutralizing CHIKV monoclonal antibodies (mAbs) have been described, but currently the only broadly neutralizing
alphavirus mAbs that have been reported are murine. Thus, the extent to which the human antibody response elicits broadly-neutralizing mAbs following alphavirus infection, and which epitope(s) such mAbs may target,
remains unknown. To address this question, this proposal seeks to expand our knowledge of the neutralizing antibody response to alphaviruses by systematically investigating cross-reactive antibodies from CHIKV-infected
patients. Towards this end, we have used single B cell sorting to isolate a large panel of MAYV-reactive mAbs from CHIKV patients in the convalescent phase. We will study the reactivity and neutralization profiles of
these mAbs against related arthitogenic alphaviruses (Aim 1). We will then biochemically determine the requirements of neutralization (Aim 2) and elucidate the mechanism of mAb inhibition (Aim 3). These studies will
contribute to our fundamental understanding of how the adaptive immune system combats infection by arthritogenic alphaviruses and may aid the development of novel mAb-based treatments and vaccines.
Bianca Ulloa - RESUMEN: Las células madre y progenitoras hematopoyéticas (HSPCs) se caracterizan por su capacidad de autorrenovación y diferenciación multipotente. Como tal, dan lugar a todos los tipos de células sanguÃÂneas maduras (por ejemplo, mieloides, linfoides y eritroides) para mantener la hematopoyesis de por vida. Su capacidad regenerativa hace que las HSPC sean valiosas para las terapias de reemplazo celular en pacientes con enfermedades hematológicas, incluidas aquellas que son secundarias a la quimioterapia y la radioterapia. La comprensión de las propiedades de autorrenovación y multipotencia de las HSPC permite el desarrollo de métodos para mejorar y maximizar su potencial terapéutico. Al estudiar los orÃÂgenes embrionarios de las capacidades de autorrenovación y diferenciación de las HSPC, pretendemos avanzar en lo que se conoce sobre estas caracterÃÂsticas definitorias de las células madre. Además de las HSPC, durante la embriogénesis se producen otros progenitores multilinaje. Estos son limitados en su producción de autorrenovación y diferenciación y en su mayorÃÂa se consideran de naturaleza transitoria. Estas poblaciones progenitoras comparten muchas caracterÃÂsticas de las células madre, lo que confunde los estudios de las propiedades de las HSPC dentro de sus entornos embrionarios nativos. Varios estudios en modelos murinos y de pez cebra sugieren que estos progenitores embrionarios, y no las HSPC, son la población dominante que genera células sanguÃÂneas maduras en el embrión. Si las HSPC no son necesarias para mantener el embrión, ¿cuál es su función durante el desarrollo? Para responder a esta pregunta, proponemos utilizar el pez cebra para determinar cuándo y dónde durante el desarrollo las HSPC se auto-renuevan y contribuyen a la producción de células sanguÃÂneas maduras en los linajes mieloides, linfoides y eritroides. Utilizaremos nuevos ensayos de regeneración y trasplante (Objetivo 1) para estudiar experimentos de autorrenovación y rastreo de linaje (Objetivo 2) para investigar la diferenciación de las HSPC. Comprender cómo se establecen y mantienen estas propiedades es fundamental para aprovechar las células madre para la medicina regenerativa.
Taylor Thompson - ABSTRACT: One major group of environmental toxicant that affect humans negatively are endocrine disrupting chemicals (EDCs). These chemicals interfere with the body’s natural hormone regulation
leading to a range of human diseases. Our research focuses on the EDC tributyltin (TBT), a chemical frequently used as a pesticide and plastic stabilizer. TBT has major adipogenic effects when exposed in utero or in
adult multipotent stem cells. Previously published data have demonstrated that TBT exposure promotes differentiation of mesenchymal stem cells (MSCs) into adipogenesis, and also increases their lipid content, representing
both numerical and qualitative effects on adipocytes. Mechanistically, TBT has been found to bind to the ligand-binding domain of the peroxisome proliferator-activated receptor gamma (PPARg) transcription factor (TF),
which is known to form a heterodimer with the RXR TF when activated, promoting a transcriptional reprogramming of MSCs to commit them to adipogenesis. MSCs can differentiate into a number of lineages, including muscle,
bone, cartilage and fibrocystic cells. When a cell undergoes transcriptional reprogramming, the sites at which the TFs bind change, reflected by alterations of the distributions of loci of open chromatin. In this project,
we propose to differentiate MSCs to both adipocytes and myocytes, initially using the cell culture conditions known to promote specific differentiation of MSCs. We will map the loci of open chromatin and test gene expression
in these samples, allowing us to identify TFs mediating these differentiation pathways by searching for motif enrichment corresponding to known TF binding sites. With this information available, we can then use the
same approaches to test how TBT causes transcriptional reprogramming, which should reveal whether the process is identical or involves a different set of TFs. Finally, we will apply the new CellTagging approach to test
cells at multiple stages of differentiation to myocytes to test whether TBT exposure affects only undifferentiated MSCs, or can also cause transdifferentiation of cells already developing in the myogenic lineage. These
new insights into the mechanism of action of TBT will be valuable in understanding how EDCs have their disease- causing effects. We will also get insights from TBT into how we a small molecule can mediate ‘epigenetic
therapy’, influencing transcriptional reprogramming but in a way that is targeted to specific genomic locations. Under the mentorship of Drs. John Greally and Paul Frenette, I will accomplish these goals while developing
new skills in developmental biology and genetics. Additionally I will gain valuable experiences in presenting, networking, and manuscript writing, all of which are essential as I train to become and independent investigator
and physician-scientist.