Publications by authors named "Jerry C Chang"

20 Publications

  • Page 1 of 1

GSAP regulates lipid homeostasis and mitochondrial function associated with Alzheimer's disease.

J Exp Med 2021 Aug 22;218(8). Epub 2021 Jun 22.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY.

Biochemical, pathogenic, and human genetic data confirm that GSAP (γ-secretase activating protein), a selective γ-secretase modulatory protein, plays important roles in Alzheimer's disease (AD) and Down's syndrome. However, the molecular mechanism(s) underlying GSAP-dependent pathogenesis remains largely elusive. Here, through unbiased proteomics and single-nuclei RNAseq, we identified that GSAP regulates multiple biological pathways, including protein phosphorylation, trafficking, lipid metabolism, and mitochondrial function. We demonstrated that GSAP physically interacts with the Fe65-APP complex to regulate APP trafficking/partitioning. GSAP is enriched in the mitochondria-associated membrane (MAM) and regulates lipid homeostasis through the amyloidogenic processing of APP. GSAP deletion generates a lipid environment unfavorable for AD pathogenesis, leading to improved mitochondrial function and the rescue of cognitive deficits in an AD mouse model. Finally, we identified a novel GSAP single-nucleotide polymorphism that regulates its brain transcript level and is associated with an increased AD risk. Together, our findings indicate that GSAP impairs mitochondrial function through its MAM localization and that lowering GSAP expression reduces pathological effects associated with AD.
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http://dx.doi.org/10.1084/jem.20202446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8222926PMC
August 2021

Brain Permeable Tafamidis Amide Analogs for Stabilizing TTR and Reducing APP Cleavage.

ACS Med Chem Lett 2020 Oct 12;11(10):1973-1979. Epub 2020 Mar 12.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York 10065, United States.

Tafamidis, , a potent transthyretin kinetic stabilizer, weakly inhibits the γ-secretase enzyme . We have synthesized four amide derivatives of . These compounds reduce production of the Aβ peptide in N2a695 cells but do not inhibit the γ-secretase enzyme in cell-free assays. By performing fluorescence correlation spectroscopy, we have shown that TTR inhibits Aβ oligomerization and that addition of tafamidis or its amide derivative does not affect TTR's ability to inhibit Aβ oligomerization. The piperazine amide derivative of tafamidis () efficiently penetrates and accumulates in mouse brain and undergoes proteolysis under physiological conditions in mice to produce tafamidis.
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http://dx.doi.org/10.1021/acsmedchemlett.9b00688DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7549266PMC
October 2020

Presenilin 1 phosphorylation regulates amyloid-β degradation by microglia.

Mol Psychiatry 2020 Aug 13. Epub 2020 Aug 13.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY, 10065, USA.

Amyloid-β peptide (Aβ) accumulation in the brain is a hallmark of Alzheimer's Disease. An important mechanism of Aβ clearance in the brain is uptake and degradation by microglia. Presenilin 1 (PS1) is the catalytic subunit of γ-secretase, an enzyme complex responsible for the maturation of multiple substrates, such as Aβ. Although PS1 has been extensively studied in neurons, the role of PS1 in microglia is incompletely understood. Here we report that microglia containing phospho-deficient mutant PS1 display a slower kinetic response to micro injury in the brain in vivo and the inability to degrade Aβ oligomers due to a phagolysosome dysfunction. An Alzheimer's mouse model containing phospho-deficient PS1 show severe Aβ accumulation in microglia as well as the postsynaptic protein PSD95. Our results demonstrate a novel mechanism by which PS1 modulates microglial function and contributes to Alzheimer's -associated phenotypes.
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http://dx.doi.org/10.1038/s41380-020-0856-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7881060PMC
August 2020

GSAP modulates γ-secretase specificity by inducing conformational change in PS1.

Proc Natl Acad Sci U S A 2019 03 8;116(13):6385-6390. Epub 2019 Mar 8.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065;

The mechanism by which γ-secretase activating protein (GSAP) regulates γ-secretase activity has not yet been elucidated. Here, we show that knockout of GSAP in cultured cells directly reduces γ-secretase activity for Aβ production, but not for Notch1 cleavage, suggesting that GSAP may induce a conformational change contributing to the specificity of γ-secretase. Furthermore, using an active-site-directed photoprobe with double cross-linking moieties, we demonstrate that GSAP modifies the orientation and/or distance of the PS1 N-terminal fragment and the PS1 C-terminal fragment, a region containing the active site of γ-secretase. This work offers insight into how GSAP regulates γ-secretase specificity.
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http://dx.doi.org/10.1073/pnas.1820160116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6442608PMC
March 2019

δ-COP modulates Aβ peptide formation via retrograde trafficking of APP.

Proc Natl Acad Sci U S A 2016 May 25;113(19):5412-7. Epub 2016 Apr 25.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065

The components involved in cellular trafficking and protein recycling machinery that have been associated with increased Alzheimer's disease (AD) risk belong to the late secretory compartments for the most part. Here, we hypothesize that these late unavoidable events might be the consequence of earlier complications occurring while amyloid precursor protein (APP) is trafficking through the early secretory pathway. We investigated the relevance to AD of coat protein complex I (COPI)-dependent trafficking, an early step in Golgi-to-endoplasmic reticulum (ER) retrograde transport and one of the very first trafficking steps. Using a complex set of imaging technologies, including inverse fluorescence recovery after photobleaching (iFRAP) and photoactivatable probes, coupled to biochemical experiments, we show that COPI subunit δ (δ-COP) affects the biology of APP, including its subcellular localization and cell surface expression, its trafficking, and its metabolism. These findings demonstrate the crucial role of δ-COP in APP metabolism and, consequently, the generation of amyloid-β (Aβ) peptide, providing previously nondescribed mechanistic explanations of the underlying events.
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http://dx.doi.org/10.1073/pnas.1604156113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868462PMC
May 2016

Single-quantum-dot tracking reveals altered membrane dynamics of an attention-deficit/hyperactivity-disorder-derived dopamine transporter coding variant.

ACS Chem Neurosci 2015 Apr 16;6(4):526-34. Epub 2015 Mar 16.

◆Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

The presynaptic, cocaine- and amphetamine-sensitive dopamine (DA) transporter (DAT, SLC6A3) controls the intensity and duration of synaptic dopamine signals by rapid clearance of DA back into presynaptic nerve terminals. Abnormalities in DAT-mediated DA clearance have been linked to a variety of neuropsychiatric disorders, including addiction, autism, and attention deficit/hyperactivity disorder (ADHD). Membrane trafficking of DAT appears to be an important, albeit incompletely understood, post-translational regulatory mechanism; its dysregulation has been recently proposed as a potential risk determinant of these disorders. In this study, we demonstrate a link between an ADHD-associated DAT mutation (Arg615Cys, R615C) and variation on DAT transporter cell surface dynamics, a combination only previously studied with ensemble biochemical and optical approaches that featured limited spatiotemporal resolution. Here, we utilize high-affinity, DAT-specific antagonist-conjugated quantum dot (QD) probes to establish the dynamic mobility of wild-type and mutant DATs at the plasma membrane of living cells. Single DAT-QD complex trajectory analysis revealed that the DAT 615C variant exhibited increased membrane mobility relative to DAT 615R, with diffusion rates comparable to those observed after lipid raft disruption. This phenomenon was accompanied by a loss of transporter mobilization triggered by amphetamine, a common component of ADHD medications. Together, our data provides the first dynamic imaging of single DAT proteins, providing new insights into the relationship between surface dynamics and trafficking of both wild-type and disease-associated transporters. Our approach should be generalizable to future studies that explore the possibilities of perturbed surface DAT dynamics that may arise as a consequence of genetic alterations, regulatory changes, and drug use that contribute to the etiology or treatment of neuropsychiatric disorders.
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http://dx.doi.org/10.1021/cn500202cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5530757PMC
April 2015

The convergence of endosomal and autophagosomal pathways: implications for APP-CTF degradation.

Autophagy 2014 Apr 16;10(4):694-6. Epub 2014 Jan 16.

Laboratory of Molecular and Cellular Neuroscience; Rockefeller University; New York, NY USA.

We have reported previously that autophagy is responsible for amyloid precursor protein-C-terminal fragment (APP-CTF) degradation and therefore Aβ clearance. To elucidate the underlying mechanism, using LC3 affinity purification and mass spectrometry analysis, immunoprecipitation (IP), as well as live imaging analysis, we identified and demonstrated that the adaptor-related protein complex 2 (AP2) and PICALM (phosphatidylinositol binding clathrin assembly protein) are in a complex with LC3 and APP-CTF. Taken together, this new set of data suggests that the AP2-PICALM complex functions as an autophagic cargo receptor for the recognition and shipment of APP-CTF from the endocytic pathway to the LC3-dependent autophagic degradation pathway. Interestingly this AP2-LC3 connection seems to be involved in chemically-induced APP-CTF clearance as we observed using the small compound SMER28. The effect observed following SMER28 was significantly reduced after silencing AP2. While more work is required to elucidate the detailed molecular mechanisms involved, our actual data suggest that there is some level of specificity in the steps mentioned above.
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http://dx.doi.org/10.4161/auto.27802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4091156PMC
April 2014

Adaptor complex AP2/PICALM, through interaction with LC3, targets Alzheimer's APP-CTF for terminal degradation via autophagy.

Proc Natl Acad Sci U S A 2013 Oct 25;110(42):17071-6. Epub 2013 Sep 25.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065.

The hallmarks of Alzheimer's disease (AD) are the aggregates of amyloid-β (Aβ) peptides and tau protein. Autophagy is a major cellular pathway leading to the removal of aggregated proteins. We have reported recently that autophagy was responsible for amyloid precursor protein cleaved C-terminal fragment (APP-CTF) degradation and amyloid β clearance in an Atg5-dependent manner. Here we aimed to elucidate the molecular mechanism by which autophagy mediates the degradation of APP-CTF and the clearance of amyloid β. Through affinity purification followed by mass spectrum analysis, we identified adaptor protein (AP) 2 together with phosphatidylinositol clathrin assembly lymphoid-myeloid leukemia (PICALM) as binding proteins of microtubule-associated protein 1 light chain 3 (LC3). Further analysis showed that AP2 regulated the cellular levels of APP-CTF. Knockdown of AP2 reduced autophagy-mediated APP-CTF degradation. Immunoprecipitation and live imaging analysis demonstrated that AP2 and PICALM cross-link LC3 with APP-CTF. These data suggest that the AP-2/PICALM complex functions as an autophagic cargo receptor for the recognition and shipment of APP-CTF from the endocytic pathway to the LC3-marked autophagic degradation pathway. This molecular mechanism linking AP2/PICALM and AD is consistent with genetic evidence indicating a role for PICALM as a risk factor for AD.
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http://dx.doi.org/10.1073/pnas.1315110110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3801056PMC
October 2013

A Bright Light to Reveal Mobility: Single Quantum Dot Tracking Reveals Membrane Dynamics and Cellular Mechanisms.

J Phys Chem Lett 2013 Aug;4(17):2858-2866

Department of Chemistry, Vanderbilt University, Nashville, TN 37235.

This perspective describes recent progress in single quantum dot techniques, with an emphasis on their applications in exploring membrane dynamics and cellular mechanisms. In these cases, conventional population measurements, such as fluorescence recovery after photobleaching, yield only a mean value on an ensemble or bulk collection of molecules, where the behavior of individual proteins and vehicles is missing. In recent years, the single quantum dot imaging approach has been introduced as a sub-category of single molecule fluorescent techniques to reveal single protein/vehicle dynamics in real-time. One of the major advantages of using single quantum dots is the high signal-to-noise ratio originating from their unique photophysical properties such as extraordinarily high molar extinction coefficients and large effective Stokes shifts. In addition to a brief overview on the principle of single quantum dot imaging techniques, we highlight recent discoveries and discuss future directions in the field.
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http://dx.doi.org/10.1021/jz401071gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5473254PMC
August 2013

Quantum dot-based single-molecule microscopy for the study of protein dynamics.

Methods Mol Biol 2013 ;1026:71-84

Department of Chemistry, Vanderbilt University, Nashville, TN, USA.

Real-time microscopic visualization of single molecules in living cells provides a molecular perspective of cellular dynamics, which is difficult to be observed by conventional ensemble techniques. Among various classes of fluorescent tags used in single-molecule tracking, quantum dots are particularly useful due to their unique photophysical properties. This chapter provides an overview of single quantum dot tracking for protein dynamic studies. First, we review the fundamental diffraction limit of conventional optical systems and recent developments in single-molecule detection beyond the diffraction barrier. Second, we describe methods to prepare water-soluble quantum dots for biological labeling and single-molecule microscopy experimental design. Third, we provide detailed methods to perform quantum dot-based single-molecule microscopy. This technical section covers three protocols including (1) imaging system calibration using spin-coated single quantum dots, (2) single quantum dot labeling in living cells, and (3) tracking algorithms for single-molecule analysis.
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http://dx.doi.org/10.1007/978-1-62703-468-5_6DOI Listing
January 2014

Single quantum dot imaging in living cells.

Methods Mol Biol 2013 ;991:149-62

Department of Chemistry, Vanderbilt University, Nashville, TN, USA.

Direct visualization of biological processes at single-molecule level provides a detailed perspective which conventional bulk measurements are hard to achieve. Among various classes of fluorescent tags used in single-molecule tracking, quantum dots are particularly useful due to their unique photophysical properties. In this chapter, we describe the principles, methodologies, and experimental protocols for qdot-based single-molecule imaging. The first half provides an overview of fluorescent microscopy and advances in single-molecule tracking using quantum dots. The remainder of this chapter describes methods to carry out qdot-based single-molecule experiments. Detailed protocols including qdot labeling, microscopy setup, and single-molecule analysis using appropriate computational programs are given.
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http://dx.doi.org/10.1007/978-1-62703-336-7_15DOI Listing
September 2013

Visualization of lipid raft membrane compartmentalization in living RN46A neuronal cells using single quantum dot tracking.

ACS Chem Neurosci 2012 Oct 1;3(10):737-43. Epub 2012 Aug 1.

Department of Chemistry and Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, USA.

Lipid rafts are cholesterol-enriched subdomains in the plasma membrane that have been reported to act as a platform to facilitate neuronal signaling; however, they are suspected to have a very short lifetime, up to only a few seconds, which calls into question their roles in biological signaling. To better understand their diffusion dynamics and membrane compartmentalization, we labeled lipid raft constituent ganglioside GM1 with single quantum dots through the connection of cholera toxin B subunit, a protein that binds specifically to GM1. Diffusion measurements revealed that single quantum dot-labeled GM1 ganglioside complexes undergo slow, confined lateral diffusion with a diffusion coefficient of ∼7.87 × 10(-2) μm(2)/s and a confinement domain about 200 nm in size. Further analysis of their trajectories showed lateral confinement persisting on the order of tens of seconds, comparable to the time scales of the majority of cellular signaling and biological reactions. Hence, our results provide further evidence in support of the putative function of lipid rafts as signaling platforms.
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http://dx.doi.org/10.1021/cn3000845DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3474263PMC
October 2012

Labeling of neuronal receptors and transporters with quantum dots.

Wiley Interdiscip Rev Nanomed Nanobiotechnol 2012 Nov-Dec;4(6):605-19. Epub 2012 Aug 9.

Department of Chemistry, Vanderbilt University, Nashville, TN, USA.

The ability to efficiently visualize protein targets in cells is a fundamental goal in biological research. Recently, quantum dots (QDots) have emerged as a powerful class of fluorescent probes for labeling membrane proteins in living cells because of breakthrough advances in QDot surface chemistry and biofunctionalization strategies. This review discusses the increasing use of QDots for fluorescence imaging of neuronal receptors and transporters. The readers are briefly introduced to QDot structure, photophysical properties, and common synthetic routes toward the generation of water-soluble QDots. The following section highlights several reports of QDot application that seek to unravel molecular aspects of neuronal receptor and transporter regulation and trafficking. This article is closed with a prospectus of the future of derivatized QDots in neurobiological and pharmacological research.
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http://dx.doi.org/10.1002/wnan.1186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753009PMC
March 2013

Visualization of the cocaine-sensitive dopamine transporter with ligand-conjugated quantum dots.

ACS Chem Neurosci 2011 Jul 26;2(7):370-8. Epub 2011 Apr 26.

Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.

The presynaptic dopamine (DA) transporter is responsible for DA inactivation following release and is a major target for the psychostimulants cocaine and amphetamine. Dysfunction and/or polymorphisms in human DAT (SLC6A3) have been associated with schizophrenia, bipolar disorder, Parkinson's disease, and attention-deficit hyperactivity disorder (ADHD). Despite the clinical importance of DAT, many uncertainties remain regarding the transporter's regulation, in part due to the poor spatiotemporal resolution of conventional methodologies and the relative lack of efficient DAT-specific fluorescent probes. We developed a quantum dot-based labeling approach that uses a DAT-specific, biotinylated ligand, 2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane (IDT444), that can be bound by streptavidin-conjugated quantum dots. Flow cytometry and confocal microscopy were used to detect DAT in stably and transiently transfected mammalian cells. IDT444 is useful for quantum-dot-based fluorescent assays to monitor DAT expression, function, and plasma membrane trafficking in living cells as evidenced by the visualization of acute, protein-kinase-C (PKC)-dependent DAT internalization.
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http://dx.doi.org/10.1021/cn200032rDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369746PMC
July 2011

Single molecule analysis of serotonin transporter regulation using antagonist-conjugated quantum dots reveals restricted, p38 MAPK-dependent mobilization underlying uptake activation.

J Neurosci 2012 Jun;32(26):8919-29

Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, USA.

The presynaptic serotonin (5-HT) transporter (SERT) is targeted by widely prescribed antidepressant medications. Altered SERT expression or regulation has been implicated in multiple neuropsychiatric disorders, including anxiety, depression and autism. Here, we implement a generalizable strategy that exploits antagonist-conjugated quantum dots (Qdots) to monitor, for the first time, single SERT proteins on the surface of serotonergic cells. We document two pools of SERT proteins defined by lateral mobility, one that exhibits relatively free diffusion, and a second, localized to cholesterol and GM1 ganglioside-enriched microdomains, that displays restricted mobility. Receptor-linked signaling pathways that enhance SERT activity mobilize transporters that, nonetheless, remain confined to membrane microdomains. Mobilization of transporters arises from a p38 MAPK-dependent untethering of the SERT C terminus from the juxtamembrane actin cytoskeleton. Our studies establish the utility of ligand-conjugated Qdots for analysis of the behavior of single membrane proteins and reveal a physical basis for signaling-mediated SERT regulation.
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http://dx.doi.org/10.1523/JNEUROSCI.0048-12.2012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3426861PMC
June 2012

A fluorescence displacement assay for antidepressant drug discovery based on ligand-conjugated quantum dots.

J Am Chem Soc 2011 Nov 17;133(44):17528-31. Epub 2011 Oct 17.

Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States.

The serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) protein plays a central role in terminating 5-HT neurotransmission and is the most important therapeutic target for the treatment of major depression and anxiety disorders. We report an innovative, versatile, and target-selective quantum dot (QD) labeling approach for SERT in single Xenopus oocytes that can be adopted as a drug-screening platform. Our labeling approach employs a custom-made, QD-tagged indoleamine derivative ligand, IDT318, that is structurally similar to 5-HT and accesses the primary binding site with enhanced human SERT selectivity. Incubating QD-labeled oocytes with paroxetine (Paxil), a high-affinity SERT-specific inhibitor, showed a concentration- and time-dependent decrease in QD fluorescence, demonstrating the utility of our approach for the identification of SERT modulators. Furthermore, with the development of ligands aimed at other pharmacologically relevant targets, our approach may potentially form the basis for a multitarget drug discovery platform.
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http://dx.doi.org/10.1021/ja204301gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235909PMC
November 2011

Real-time quantum dot tracking of single proteins.

Methods Mol Biol 2011 ;726:51-62

Department of Chemistry, Vanderbilt University, Nashville, TN, USA.

We describe a single quantum dot tracking method that can be used to monitor individual proteins in the membrane of living cells. Unlike conventional fluorescent dyes, quantum dots (fluorescent semiconductor nanocrystals) have high quantum yields, narrow emission wavelengths, and excellent photostability, making them ideal probes in single-molecule detection. This technique has been applied to study the dynamics of various membrane proteins including glycine receptors, nerve growth factors, kinesin motors, and γ-aminobutyric acid receptors. In this chapter, a basic introduction and experimental setup for single quantum dot labeling of a target protein is given. In addition, data acquisition and analysis of time-lapse single quantum dot imaging with sample protocols are provided.
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http://dx.doi.org/10.1007/978-1-61779-052-2_4DOI Listing
June 2011

Biocompatible quantum dots for biological applications.

Chem Biol 2011 Jan;18(1):10-24

Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA.

Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-tunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots.
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http://dx.doi.org/10.1016/j.chembiol.2010.11.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3752999PMC
January 2011

The protease-mediated nucleus shuttles of subnanometer gold quantum dots for real-time monitoring of apoptotic cell death.

J Am Chem Soc 2010 Jun;132(24):8309-15

Center for Nanomedicine Research, National Health Research Institutes, 35 Keyan Road Zhunan, Miaoli, Taiwan.

Subnanometer photoluminescent gold quantum dots (GQDs) are functionalized with a peptide moiety that contains both nuclear export signal (NES) and nuclear localization signal (NLS) sequences. By taking advantage of its small size and great photostability, the functionalized GQDs are used to mimic the actions of nucleus shuttle proteins, especially of those activated during cell apoptotic death, to work as protease-mediated cytoplasm-nucleus shuttles for dynamic monitoring of apoptosis. The resulting construct demonstrates activation of the nuclear pore complex (NPC) of cells, for bidirectional transport between nucleus and cytoplasm. A caspase-3 recognition sequence (DEVD), placed within the NLS/NES peptide, serves as a proteolytic site for activated caspase-3. Upon the induction of apoptosis, the activated caspase-3 cleaves the functional peptide on GQDs resulting in changes of subcellular distribution of GQDs. Such changes can be quantified as a function of time, by the ratios of GQDs photoluminescence in nucleus to that in cytoplasm. As such, the NES-linker-DEVD-linker-NLS peptide enables the GQDs to function as molecular probes for the real-time monitoring of cellular apoptosis.
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http://dx.doi.org/10.1021/ja100561kDOI Listing
June 2010

Controlling the reactivity of ampiphilic quantum dots in biological assays through hydrophobic assembly of custom PEG derivatives.

Bioconjug Chem 2008 Jul 5;19(7):1404-13. Epub 2008 Jun 5.

Department of Chemistry, Vanderbilt University, Station B, 351822, Nashville, Tennessee, 37235-1822, USA.

Modifications of the quantum dot (QD) surface are routinely performed via covalent biomolecule attachment, and poly(ethylene glycol) (PEG) derivatization has previously been shown to limit nonspecific cellular interactions of QD probes. Attempts to functionalize ampiphilic QDs (AMP-QDs) with custom PEG derivatives having a hydrophobic terminus resulted in self-assembly of these PEG ligands to the AMP-QD surface in the absence of covalent coupling reagents. We demonstrate, via electrophoretic characterization techniques, that these self-assembled PEG-QDs exhibit improved passivation in biological environments and are less susceptible to unwanted protein adsorption to the QD surface. We highlight the artifactual fluorescent response protein adsorption can cause in biological assays, and discuss considerations for improved small molecule presentation to facilitate specific QD interactions.
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http://dx.doi.org/10.1021/bc800104nDOI Listing
July 2008
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