Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 13 de 13
Filter
Add more filters










Publication year range
1.
J Microbiol Biol Educ ; 23(3)2022 Dec.
Article in English | MEDLINE | ID: mdl-36532223

ABSTRACT

Service-learning and undergraduate research experiences are high-impact practices that have become more common in the sciences, but the benefits of short-term experiences have not been thoroughly investigated. The purpose of this study was to compare within-semester gains for students in a short-term service-learning (SL) or short-term research project (RP) in terms of students' (i) motivation to learn biology, (ii) scientific literacy, (iii) perception of the relevance of biology to their lives, and (iv) learning gains associated with course learning outcomes. The impacts of brief service-learning and research project experiences were compared using direct and indirect assessments, including qualitative coding of open-ended response questions and quantitative analysis of exams and Likert-type items. We found few differences between students in the two projects regarding their changes in motivation (both slightly negative), scientific literacy (both gains), and their ability to connect biology to their lives (both gains). Emergent themes revealed that both projects influenced students' plans for future research and service-learning. Both projects helped students build relationships; however, RP students built relationships with classmates, while SL students built relationships with community members. The positive experiences highlight the need for engaging science students through service-learning in addition to research.

2.
Article in English | MEDLINE | ID: mdl-32431766

ABSTRACT

Creation of an inclusive environment requires a culture of equity, justice, value and respect for diverse backgrounds, and opportunities for students to engage with communities while addressing issues in science and society. These tasks are particularly challenging for institutions lacking a diverse population. Here, we demonstrate evidence of a successful model for creating an inclusive environment in an interinstitutional course between a large, public, historically black institution and a small, private, primarily white institution. Because many individuals from underrepresented minority groups tend to value communal goals of working together and helping their communities, we incorporated two high-impact practices of community-engaged learning and course-based undergraduate research experiences (CUREs) focused on health disparities research in neighboring communities. Although the research projects varied each semester, they were linked by their impact on and engagement with the community. Students practiced cultural competency skills in both small group projects within the class and engagement activities in the community. We measured the efficacy of CURE components (novel authentic research, scientific process skills, iteration, collaboration, and broader impact) through a combination of direct and indirect assessments, quantitative and qualitative analysis. More than simply scientific skills, students from both institutions developed lasting interest in working with diverse populations as well as respecting and valuing different backgrounds. This inclusive environment, combined with increased interest in research, suggests that this course could potentially serve as a model for interinstitutional collaborations in creating inclusive environments that support the future success of diverse students, eventually changing the STEM research culture.

3.
Blood ; 124(7): 1127-35, 2014 Aug 14.
Article in English | MEDLINE | ID: mdl-24994068

ABSTRACT

Acute myeloid leukemia (AML) often relapses following chemotherapy-induced remission and is generally chemo-resistant. Given the potential role for cancer stem cells in relapse, targeting of the leukemia-initiating cell (LIC) in AML may provide improved outcome following remission induction. However, due to overlap in their self-renewal program with normal hematopoietic stem cells (HSCs), therapeutic targeting of the LIC may have an adverse effect on long-term hematopoietic recovery. Here we used a mouse model of relapsed AML to explore whether the hypoxia-inducible factor (HIF)1α inhibitor echinomycin can be used to treat relapsed AML without affecting host HSCs. We show that echinomycin cured 40% to 60% of mice transplanted with relapsed AML. Bone marrow cells from the cured mice displayed normal composition of HSCs and their progenitors and were as competent as those isolated from nonleukemic mice in competitive repopulation assays. Importantly, in mice with complete remission, echinomycin appeared to completely eliminate LICs because no leukemia could be propagated in vivo following serial transplantation. Taken together, our data demonstrate that in a mouse model of relapsed AML, low-dose echinomycin selectively targets LICs and spares normal hematopoiesis.


Subject(s)
Echinomycin/pharmacology , Hematopoietic Stem Cells/drug effects , Leukemia, Myeloid/drug therapy , Neoplastic Stem Cells/drug effects , Acute Disease , Animals , Antibiotics, Antineoplastic/pharmacology , Bone Marrow Transplantation , Flow Cytometry , Hematopoietic Stem Cells/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/antagonists & inhibitors , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Leukemia, Myeloid/genetics , Leukemia, Myeloid/metabolism , Mice, Knockout , Neoplasm Recurrence, Local , Neoplastic Stem Cells/metabolism , RNA Interference , Remission Induction , Time Factors , Treatment Outcome
4.
Blood ; 122(23): 3778-83, 2013 Nov 28.
Article in English | MEDLINE | ID: mdl-24085765

ABSTRACT

The coexpression of the MLL partial tandem duplication (PTD) and the FLT3 internal tandem duplication (ITD) mutations associate with a poor outcome in cytogenetically normal acute myeloid leukemia (AML). In mice, a double knock-in (dKI) of Mll(PTD/wt) and Flt3(ITD/wt) mutations induces spontaneous AML with an increase in DNA methyltransferases (Dnmt1, 3a, and 3b) and global DNA methylation index, thereby recapitulating its human AML counterpart. We determined that a regulator of Dnmts, miR-29b, is downregulated in bone marrow of dKI AML mice. Bortezomib exerted a dose-dependent increase in miR-29b expression in AML blasts ex vivo, followed by decreased Dnmts, reduced proliferation, and increased apoptosis. In vivo, bortezomib was not active against dKI AML, yet liposomal-encapsulated bortezomib, as a single agent, reversed downregulation of miR-29b in vivo and induced a long-term (90-day) disease-free remission in 80% of dKI AML mice that exhibited high leukemic burden at the start of therapy, yet showed no signs of relapse at autopsy. Taken together, these data support that liposomal bortezomib, as a single agent, eradicates Mll(PTD/wt):Flt3(ITD/wt) AML in mouse and may represent a powerful and potentially curative approach to high-risk human disease.


Subject(s)
Histone-Lysine N-Methyltransferase/genetics , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/therapy , Myeloid-Lymphoid Leukemia Protein/genetics , fms-Like Tyrosine Kinase 3/genetics , Animals , Antineoplastic Agents/administration & dosage , Boronic Acids/administration & dosage , Bortezomib , DNA Methylation , Drug Carriers , Humans , Leukemia, Experimental/genetics , Leukemia, Experimental/metabolism , Leukemia, Experimental/therapy , Leukemia, Myeloid, Acute/metabolism , Liposomes , Mice , Mice, Mutant Strains , MicroRNAs/genetics , MicroRNAs/metabolism , Mutation , Proteasome Inhibitors/administration & dosage , Pyrazines/administration & dosage , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Tandem Repeat Sequences
5.
Blood ; 120(5): 1130-6, 2012 Aug 02.
Article in English | MEDLINE | ID: mdl-22674806

ABSTRACT

The MLL-partial tandem duplication (PTD) associates with high-risk cytogenetically normal acute myeloid leukemia (AML). Concurrent presence of FLT3-internal tandem duplication (ITD) is observed in 25% of patients with MLL-PTD AML. However, mice expressing either Mll-PTD or Flt3-ITD do not develop AML, suggesting that 2 mutations are necessary for the AML phenotype. Thus, we generated a mouse expressing both Mll-PTD and Flt3-ITD. Mll(PTD/WT):Flt3(ITD/WT) mice developed acute leukemia with 100% penetrance, at a median of 49 weeks. As in human MLL-PTD and/or the FLT3-ITD AML, mouse blasts exhibited normal cytogenetics, decreased Mll-WT-to-Mll-PTD ratio, loss of the Flt3-WT allele, and increased total Flt3. Highlighting the adverse impact of FLT3-ITD dosage on patient survival, mice with homozygous Flt3-ITD alleles, Mll(PTD/WT):Flt3(ITD/ITD), demonstrated a nearly 30-week reduction in latency to overt AML. Here we demonstrate, for the first time, that Mll-PTD contributes to leukemogenesis as a gain-of-function mutation and describe a novel murine model closely recapitulating human AML.


Subject(s)
Gene Duplication/physiology , Gene Knock-In Techniques , Leukemia, Myeloid, Acute/genetics , Myeloid-Lymphoid Leukemia Protein/genetics , fms-Like Tyrosine Kinase 3/genetics , Animals , Cell Transformation, Neoplastic/genetics , Disease Models, Animal , Histone-Lysine N-Methyltransferase , Humans , Leukemia, Myeloid, Acute/pathology , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Transgenic , Tandem Repeat Sequences/genetics
6.
Proc Natl Acad Sci U S A ; 108(7): 2885-90, 2011 Feb 15.
Article in English | MEDLINE | ID: mdl-21282648

ABSTRACT

Linker for activation of T cells (LAT) plays a central role in T-cell activation by nucleating signaling complexes that are critical for the propagation of T-cell signals from the plasma membrane to the cellular interior. The role of phosphorylation and palmitoylation in LAT function has been well studied, but not much is known about other strategies by which the cell modulates LAT activity. We have focused on LAT ubiquitylation and have mapped the sites on which LAT is ubiquitylated. To elucidate the biological role of this process, we substituted LAT lysines with arginines. This resulted in a dramatic decrease in overall LAT ubiquitylation. Ubiquitylation-resistant mutants of LAT were internalized at rates comparable to wild-type LAT in a mechanism that required Cbl family proteins. However, these mutants displayed a defect in protein turnover rates. T-cell signaling was elevated in cells reconstituted with LAT mutants resistant to ubiquitylation, indicating that inhibition of LAT ubiquitylation enhances T-cell potency. These results support LAT ubiquitylation as a molecular checkpoint for attenuation of T-cell signaling.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Lymphocyte Activation/physiology , Membrane Proteins/metabolism , Signal Transduction/immunology , T-Lymphocytes/physiology , Adaptor Proteins, Signal Transducing/genetics , Animals , Antibodies, Monoclonal , COS Cells , Chlorocebus aethiops , DNA Primers/genetics , Flow Cytometry , Fluorescence , Humans , Immunoblotting , Immunoprecipitation , Jurkat Cells , Membrane Proteins/genetics , Microscopy, Confocal , Mutation/genetics , Polymerase Chain Reaction , RNA Interference , RNA, Small Interfering/genetics , Transfection , Ubiquitination
7.
Immunol Rev ; 231(1): 148-59, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19754895

ABSTRACT

In the last few years, great progress has been made in understanding how stromal interacting molecule 1 (STIM1), a protein containing a calcium sensor that is located in the endoplasmic reticulum, and Orai1, a protein that forms a calcium channel in the plasma membrane, interact and give rise to store-operated calcium entry. Pharmacological depletion of calcium stores leads to the formation of clusters containing STIM and Orai that appear to be sites for calcium influx. Similar puncta are also produced in response to physiological stimuli in immune cells. In T cells engaged with antigen-presenting cells, clusters containing STIM and Orai accumulate at the immunological synapse. We recently discovered that in activated T cells, STIM1 and Orai1 also accumulate in cap-like structures opposite the immune synapse at the distal pole of the cell. Both caps and puncta are long-lived stable structures containing STIM1 and Orai1 in close proximity. The function of puncta as sites of calcium influx is clear. We speculate that the caps may provide a secondary site of calcium entry. Alternatively, they may serve as a source of preformed channel complexes that move to new immune synapses as T cells repeatedly engage antigen-presenting cells.


Subject(s)
Calcium Channels/metabolism , Membrane Proteins/metabolism , T-Lymphocytes/cytology , T-Lymphocytes/metabolism , Animals , Calcium/metabolism , Calcium Channels/chemistry , Humans , Membrane Proteins/chemistry , Protein Binding , Signal Transduction , T-Lymphocytes/chemistry , T-Lymphocytes/immunology
8.
Mol Biol Cell ; 19(7): 2802-17, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18448669

ABSTRACT

The proteins STIM1 and Orai1 are the long sought components of the store-operated channels required in T-cell activation. However, little is known about the interaction of these proteins in T-cells after engagement of the T-cell receptor. We found that T-cell receptor engagement caused STIM1 and Orai1 to colocalize in puncta near the site of stimulation and accumulate in a dense structure on the opposite side of the T-cell. FRET measurements showed a close interaction between STIM1 and Orai1 both in the puncta and in the dense cap-like structure. The formation of cap-like structures did not entail rearrangement of the entire endoplasmic reticulum. Cap formation depended on TCR engagement and tyrosine phosphorylation, but not on channel activity or Ca(2+) influx. These caps were very dynamic in T-cells activated by contact with superantigen pulsed B-cells and could move from the distal pole to an existing or a newly forming immunological synapse. One function of this cap may be to provide preassembled Ca(2+) channel components to existing and newly forming immunological synapses.


Subject(s)
Calcium Channels/chemistry , Calcium Signaling , Membrane Proteins/metabolism , Neoplasm Proteins/metabolism , T-Lymphocytes/metabolism , B-Lymphocytes/metabolism , Calcium/chemistry , Calcium/metabolism , Calcium Channels/metabolism , Cell Membrane/metabolism , Humans , Immunological Synapses/metabolism , Jurkat Cells , Lymphocyte Activation , Microscopy, Fluorescence , Models, Biological , ORAI1 Protein , Phosphorylation , Stromal Interaction Molecule 1
9.
J Biol Chem ; 283(26): 18323-30, 2008 Jun 27.
Article in English | MEDLINE | ID: mdl-18450757

ABSTRACT

Upon antigen recognition, T-cell receptor (TCR/CD3) and other signaling molecules become enriched in a specialized contact site between the T cell and antigen-presenting cell, i.e. the immunological synapse (IS). Enrichment occurs via mechanisms that include polarized secretion from recycling endosomes, but the Rabs and RabGAPs that regulate this are unknown. EPI64C (TBC1D10C) is an uncharacterized candidate RabGAP we identified by mass spectrometry as abundant in human peripheral blood T cells that is preferentially expressed in hematopoietic cells. EPI64C is a Rab35-GAP based both on in vitro Rab35-specific GAP activity and findings in transfection assays. EPI64C and Rab35 dominant negative (DN) constructs each impaired transferrin export from a recycling pathway in Jurkat T-cells and induced large vacuoles marked by transferrin receptor, TCR, and SNAREs implicated in TCR-polarized secretion. Rab35 localized to the plasma membrane and to intracellular vesicles where it substantially colocalized with TfR and with TCR. Rab35 was strongly recruited to the IS. Conjugate formation was impaired by transfection with Rab35-DN or EPI64C and by EPI64C knock down. TCR enrichment at the IS was impaired by Rab35-DN. Thus, EPI64C and Rab35 regulate a recycling pathway in T cells and contribute to IS formation, most likely by participating in TCR transport to the IS.


Subject(s)
GTPase-Activating Proteins/chemistry , Gene Expression Regulation , Synapses/metabolism , T-Lymphocytes/metabolism , rab GTP-Binding Proteins/physiology , Endosomes/metabolism , Humans , Immune System , Jurkat Cells , Microscopy, Confocal , Models, Biological , RNA Interference , Signal Transduction , Transfection , rab GTP-Binding Proteins/chemistry
10.
Traffic ; 7(9): 1143-62, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16919152

ABSTRACT

T-cell antigen receptor engagement causes the rapid assembly of signaling complexes. The adapter protein SLP-76, detected as SLP-yellow fluorescent protein, initially clustered with the TCR and other proteins, then translocated medially on microtubules. As shown by total internal reflection fluorescence microscopy and the inhibition of SLP-76 movement at 16 degrees C, this movement required endocytosis. Immunoelectron microscopy showed SLP-76 staining of smooth pits and tubules. Cholesterol depletion decreased the movement of SLP-76 clusters, as did coexpression of the ubiquitin-interacting motif domain from eps15. These data are consistent with the internalization of SLP-76 via a lipid raft-dependent pathway that requires interaction of the endocytic machinery with ubiquitinylated proteins. The endocytosed SLP-76 clusters contained phosphorylated SLP-76 and phosphorylated LAT. The raft-associated, transmembrane protein LAT likely targets SLP-76 to endocytic vesicles. The endocytosis of active SLP-76 and LAT complexes suggests a possible mechanism for downregulation of signaling complexes induced by TCR activation.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Cholesterol/physiology , Endocytosis/physiology , Phosphoproteins/metabolism , Receptors, Antigen, T-Cell/physiology , Signal Transduction/physiology , Humans
11.
J Cell Biol ; 168(6): 965-74, 2005 Mar 14.
Article in English | MEDLINE | ID: mdl-15767464

ABSTRACT

Intermediate filaments (IFs) are fibrous polymers encoded by a large family of differentially expressed genes that provide crucial structural support in the cytoplasm and nucleus in higher eukaryotes. The mechanisms involved in bringing together approximately 16 elongated coiled-coil dimers to form an IF are poorly defined. Available evidence suggests that tetramer subunits play a key role during IF assembly and regulation. Through molecular modeling and site-directed mutagenesis, we document a hitherto unnoticed hydrophobic stripe exposed at the surface of coiled-coil keratin heterodimers that contributes to the extraordinary stability of heterotetramers. The inability of K16 to form urea-stable tetramers in vitro correlates with an increase in its turnover rate in vivo. The data presented support a specific conformation for the assembly competent IF tetramer, provide a molecular basis for their differential stability in vitro, and point to the physiological relevance associated with this property in vivo.


Subject(s)
Hydrophobic and Hydrophilic Interactions , Keratins/chemistry , Keratins/metabolism , Amino Acid Sequence , Amino Acid Substitution , Animals , Cells, Cultured , Chromatography, Ion Exchange , Consensus Sequence , Cross-Linking Reagents/pharmacology , Dimerization , Electrophoresis, Agar Gel , Electrophoresis, Polyacrylamide Gel , Escherichia coli/genetics , Humans , Keratinocytes , Keratins/genetics , Keratins/ultrastructure , Mice , Models, Molecular , Molecular Sequence Data , Mutagenesis, Site-Directed , Precipitin Tests , Protein Conformation , Protein Structure, Tertiary , Recombinant Proteins/analysis , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid
13.
J Invest Dermatol ; 119(5): 1137-49, 2002 Nov.
Article in English | MEDLINE | ID: mdl-12445204

ABSTRACT

The morphogenesis of skin epithelia and adult hair follicle cycling both require integrated signaling between the epithelium and underlying mesenchyme. Because of their unique regulation, keratin intermediate filaments represent useful markers for the analysis of determination and differentiation processes in complex epithelia, such as the skin. In this study, we analyzed the distribution of mouse type I keratin 16 during skin morphogenesis, in the adult hair cycle, and in challenged epidermis. In mature hair follicles, we find keratin 16 along with its type II keratin partner keratin 6 in the companion layer of the outer root sheath during anagen and in the club hair sheath during catagen and telogen. During embryonic development, the distribution of keratin 16 is uncoupled from its presumed polymerization partner, keratin 6. Keratin 16 initially localizes within early hair germs, but rapidly shifts to a subset of cells at the interface of basal and suprabasal cells above and around the hair germ. The presence of keratin 16 at the transition between mitotically active and differentiating cells is recapitulated in primary keratinocytes cultured in vitro and in phorbol 12-myristate 13-acetate-treated back skin in vivo. We propose that keratin 16 marks cells in an intermediate state of cellular properties in which keratinocytes retain the flexibility required for activities such as cell migration and even mitosis but are resilient enough to provide the structural integrity required of the early suprabasal layers in the context of development, adult hair cycling, and wound repair.


Subject(s)
Epithelial Cells/cytology , Epithelial Cells/physiology , Hair Follicle/cytology , Hair Follicle/physiology , Keratins/genetics , Age Factors , Animals , Cell Differentiation/physiology , Cells, Cultured , Cloning, Molecular , DNA, Complementary , Gene Expression Regulation, Developmental/physiology , Hair Follicle/embryology , Mice , Mice, Inbred Strains , Serine/genetics , Sweat Glands/cytology , Sweat Glands/embryology , Sweat Glands/physiology , Wound Healing/physiology
SELECTION OF CITATIONS
SEARCH DETAIL
...