Publications by authors named "Anna S Nam"

13 Publications

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Integrating genetic and non-genetic determinants of cancer evolution by single-cell multi-omics.

Nat Rev Genet 2021 01 17;22(1):3-18. Epub 2020 Aug 17.

New York Genome Center, New York, NY, USA.

Cancer represents an evolutionary process through which growing malignant populations genetically diversify, leading to tumour progression, relapse and resistance to therapy. In addition to genetic diversity, the cell-to-cell variation that fuels evolutionary selection also manifests in cellular states, epigenetic profiles, spatial distributions and interactions with the microenvironment. Therefore, the study of cancer requires the integration of multiple heritable dimensions at the resolution of the single cell - the atomic unit of somatic evolution. In this Review, we discuss emerging analytic and experimental technologies for single-cell multi-omics that enable the capture and integration of multiple data modalities to inform the study of cancer evolution. These data show that cancer results from a complex interplay between genetic and non-genetic determinants of somatic evolution.
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http://dx.doi.org/10.1038/s41576-020-0265-5DOI Listing
January 2021

DNA methylation disruption reshapes the hematopoietic differentiation landscape.

Nat Genet 2020 04 23;52(4):378-387. Epub 2020 Mar 23.

New York Genome Center, New York, NY, USA.

Mutations in genes involved in DNA methylation (DNAme; for example, TET2 and DNMT3A) are frequently observed in hematological malignancies and clonal hematopoiesis. Applying single-cell sequencing to murine hematopoietic stem and progenitor cells, we observed that these mutations disrupt hematopoietic differentiation, causing opposite shifts in the frequencies of erythroid versus myelomonocytic progenitors following Tet2 or Dnmt3a loss. Notably, these shifts trace back to transcriptional priming skews in uncommitted hematopoietic stem cells. To reconcile genome-wide DNAme changes with specific erythroid versus myelomonocytic skews, we provide evidence in support of differential sensitivity of transcription factors due to biases in CpG enrichment in their binding motif. Single-cell transcriptomes with targeted genotyping showed similar skews in transcriptional priming of DNMT3A-mutated human clonal hematopoiesis bone marrow progenitors. These data show that DNAme shapes the topography of hematopoietic differentiation, and support a model in which genome-wide methylation changes are transduced to differentiation skews through biases in CpG enrichment of the transcription factor binding motif.
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http://dx.doi.org/10.1038/s41588-020-0595-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216752PMC
April 2020

Somatic mutations and cell identity linked by Genotyping of Transcriptomes.

Nature 2019 07 3;571(7765):355-360. Epub 2019 Jul 3.

New York Genome Center, New York, NY, USA.

Defining the transcriptomic identity of malignant cells is challenging in the absence of surface markers that distinguish cancer clones from one another, or from admixed non-neoplastic cells. To address this challenge, here we developed Genotyping of Transcriptomes (GoT), a method to integrate genotyping with high-throughput droplet-based single-cell RNA sequencing. We apply GoT to profile 38,290 CD34 cells from patients with CALR-mutated myeloproliferative neoplasms to study how somatic mutations corrupt the complex process of human haematopoiesis. High-resolution mapping of malignant versus normal haematopoietic progenitors revealed an increasing fitness advantage with myeloid differentiation of cells with mutated CALR. We identified the unfolded protein response as a predominant outcome of CALR mutations, with a considerable dependency on cell identity, as well as upregulation of the NF-κB pathway specifically in uncommitted stem cells. We further extended the GoT toolkit to genotype multiple targets and loci that are distant from transcript ends. Together, these findings reveal that the transcriptional output of somatic mutations in myeloproliferative neoplasms is dependent on the native cell identity.
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http://dx.doi.org/10.1038/s41586-019-1367-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6782071PMC
July 2019

TARGET-seq Takes Aim at Cancer Evolution through Multi-omics Single-Cell Genotyping and Transcriptomics.

Mol Cell 2019 03;73(6):1092-1094

Division of Hematology and Medical Oncology, Department of Medicine and Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA; New York Genome Center, New York, NY, USA; Institute for Computational Biomedicine, Weill Cornell Medicine, New York, NY, USA. Electronic address:

In this issue of Molecular Cell, Rodriguez-Meira et al. (2019) present TARGET-seq, an elegant single-cell method that genotypes somatic mutations and captures whole transcriptomes in the same tumor cells, thus paving the way to directly link somatic mutations with resulting transcriptional phenotypes in clonally diverse cancer populations.
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http://dx.doi.org/10.1016/j.molcel.2019.03.009DOI Listing
March 2019

Surf4 (Erv29p) binds amino-terminal tripeptide motifs of soluble cargo proteins with different affinities, enabling prioritization of their exit from the endoplasmic reticulum.

PLoS Biol 2018 08 7;16(8):e2005140. Epub 2018 Aug 7.

Matrix Biochemistry Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America.

Some secreted proteins that assemble into large complexes, such as extracellular matrices or hormones and enzymes in storage granules, must be kept at subaggregation concentrations during intracellular trafficking. We show surfeit locus protein 4 (Surf4) is the cargo receptor that establishes different steady-state concentrations for a variety of soluble cargo proteins within the endoplasmic reticulum (ER) through interaction with the amino-terminal tripeptides exposed after removal of leader sequences. We call this motif the ER-Exit by Soluble Cargo using Amino-terminal Peptide-Encoding motif (ER-ESCAPE motif). Proteins that most readily aggregate in the ER lumen (e.g., dentin sialophosphoprotein [DSPP] and amelogenin, X-linked [AMELX]) have strong ER-ESCAPE motifs to inhibit aggregate formation, while less susceptible cargo exhibits weaker motifs. Specific changes in a single amino acid of the tripeptide result in aggregate formation and failure to efficiently traffic cargo out of the ER. A logical subset of 8,000 possible tripeptides starting a model soluble cargo protein (growth hormone) established a continuum of steady-state ER concentrations ranging from low (i.e., high affinity for receptor) to the highest concentrations associated with bulk flow-limited trafficking observed for nonbinding motifs. Human cells lacking Surf4 no longer preferentially trafficked cargo expressing strong ER-ESCAPE motifs. Reexpression of Surf4 or expression of yeast's ortholog, ER-derived vesicles protein 29 (Erv29p), rescued enhanced ER trafficking in Surf4-null cells. Hence our work describes a new way of preferentially exporting soluble cargo out of the ER that maintains proteins below the concentrations at which they form damaging aggregates.
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http://dx.doi.org/10.1371/journal.pbio.2005140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6097701PMC
August 2018

Assessment of the Utility of Cytology and Flow Cytometry of Cerebrospinal Fluid Samples in Clinical Practice.

Acta Cytol 2018 6;62(2):130-136. Epub 2018 Mar 6.

Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, USA.

Objectives: We sought to assess the utility and limitations of both flow cytometry (FC) and cytology for the analysis of cerebrospinal fluid (CSF) in a practical clinical setting.

Methods: A total of 393 consecutive CSF samples from 171 patients submitted for both cytomorphologic and FC assessments were analyzed.

Results: Both FC and cytology findings were negative for malignancy in 315/393 samples (80%), and either positive (POS) or suspicious/atypical (SUSP/AT) in 7% of samples. This resulted in high agreement between FC and cytology (87%). Minor discrepancies were present in 4% of the cases. In 28 samples, an abnormal population was detected by FC but not by cytology.

Conclusions: FC and cytology are important complementary methods for analyzing CSF samples. In cases where cytology is SUSP/AT and FC is inconclusive or negative, additional specimens should be submitted for immunostaining, cytogenetics, and/or molecular studies.
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http://dx.doi.org/10.1159/000487070DOI Listing
April 2018

An intrasinusoidal extracavitary variant of primary effusion lymphoma.

Blood 2017 08;130(6):836

Weill Cornell Medicine.

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http://dx.doi.org/10.1182/blood-2017-04-780593DOI Listing
August 2017

Cytologic diagnosis of adrenal oncocytic pheochromocytoma in a lung cancer patient: Report of a case and review of the literature.

Cytojournal 2015 25;12. Epub 2015 Mar 25.

Address: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York-Presbyterian Hospital, New York, USA.

Adrenal oncocytic pheochromocytoma is an extremely rare type of pheochromocytoma. To the best of our knowledge, we present the first cytological diagnosis of this variant via fine-needle aspiration in an 81-year-old male patient who was found to have an adrenal mass while undergoing workup of the recently diagnosed lung adenocarcinoma. We describe the cytomorphologic findings in our case and provide a review of the reported cases of adrenal oncocytic pheochromocytoma - all of which appear to be benign, nonfunctional, occur in adults, and have similar morphologic features. The pathologist should be aware of this uncommon diagnostic entity and its potential diagnostic pitfalls.
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http://dx.doi.org/10.4103/1742-6413.153959DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4382977PMC
April 2015

Efficient trafficking of acidic proteins out of the endoplasmic reticulum involves a conserved amino terminal IleProVal (IPV)-like tripeptide motif.

Connect Tissue Res 2014 Aug;55 Suppl 1:138-41

Matrix Biochemistry Section, CSDB, NIDCR, NIH , Bethesda, MD , USA.

Most of the proposed extracellular biomineralization processes include the secretion of proteins that interact with mineral ions and/or mineral surfaces. Typically these proteins are acidic or have acidic domains that interact with multivalent cations in the extracellular environment. We propose that most acidic, Ca(2+)-binding proteins challenge the cell's mechanisms for trafficking through the endoplasmic reticulum (ER) lumen due to lumenal mM calcium that cause them to form large aggregates. We have recently shown that >95% of the DSPP mutations that cause non-syndromic genetic dentin diseases start their dominant negative affects by failing to rapidly exit the ER likely by forming complexes that cannot be normally trafficked to the Golgi. The complexes of mutant DSPP then capture more (severe disease) or less (mild disease) of the DSPP translated from the normal allele. After searching genomic databases as well as the published literature, we found the IleProVal (IPV)-like motif at the predicted amino terminus of many acidic proteins made in the mineralizing as well as non-mineralizing tissues of many species including vertebrates, echinoderms, mollusks, and yeast. While we often focused on acidic proteins reported associated with mineralizing structures, proteins associated with hormones and their storage/secretion, digestion, blood functions, as well as milk and other secreted fluids started with variations of the motif. Our hypothesis is that the IPV-like motif interacts with a highly conserved cargo receptor in the ER that efficiently traffics the acidic proteins out of the organelle before they can form harmful aggregates in the Ca(2+)-rich lumen.
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http://dx.doi.org/10.3109/03008207.2014.923852DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4153534PMC
August 2014

Interleukin-6 expands homeostatic space for peripheral T cells.

Cytokine 2013 Nov 26;64(2):532-40. Epub 2013 Aug 26.

Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA.

T cell homeostasis and survival is dependent on interleukin-7 (IL-7). Immune activation, however, downregulates IL-7 receptor expression on T cells so that T cell survival during activation must be maintained independently of IL-7. The pro-inflammatory cytokine IL-6 shares common signaling pathways with IL-7 and can promote T cell survival in vitro. But whether IL-6 promotes T cell survival and homeostasis in vivo is not clear. Notably, IL-6 overexpression results in massive plasmacytosis and autoimmunity so that an IL-6 effect on in vivo T cell survival has remained untested. To overcome this limitation, here we generated IL-6 transgenic mice on an immunoglobulin heavy chain (IgH) deficient background which rendered them B cell deficient. Notably, such IgH(KO)IL6(Tg) mice were free of any signs of inflammation or autoimmunity and remained healthy throughout the course of analysis. In these mice, we found that IL-6 overexpression significantly increased peripheral T cell numbers, but importantly without increasing thymopoiesis. Moreover, IL-6 signaled T cells maintained their naïve phenotype and did not express activation/memory markers, suggesting that increased T cell numbers were due to increased T cell survival and not because of expansion of activated T cells. Mechanistically, we found that IL-6 signaling induced expression of pro-survival factors Mcl-1 and Pim-1/-2 but not Bcl-2. Thus, IL-6 is a T cell homeostatic cytokine that expands T cell space and can maintain the naïve T cell pool.
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http://dx.doi.org/10.1016/j.cyto.2013.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3806195PMC
November 2013

Pim1 permits generation and survival of CD4+ T cells in the absence of γc cytokine receptor signaling.

Eur J Immunol 2013 Sep 21;43(9):2283-94. Epub 2013 Jun 21.

Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Division of Graduate Medical Sciences, Boston University School of Medicine, Boston, MA, USA.

γ-Chain (γc) cytokine receptor signaling is required for the development of all lymphocytes. Why γc signaling plays such an essential role is not fully understood, but induction of the serine/threonine kinase Pim1 is considered a major downstream event of γc as Pim1 prevents apoptosis and increases metabolic activity. Consequently, we asked whether Pim1 overexpression would suffice to restore lymphocyte development in γc-deficient mice. By analyzing Pim1-transgenic γc-deficient mice (Pim1(Tg) γc(KO) ), we show that Pim1 promoted T-cell development and survival in the absence of γc. Interestingly, such effects were largely limited to CD4(+) lineage αβ T cells as CD4(+) T-cell numbers improved to near normal levels but CD8(+) T cells remained severely lymphopenic. Notably, Pim1 over-expression failed to promote development and survival of any T-lineage cells other than αβ T cells, as we observed complete lack of γδ, NKT, FoxP3(+) T regulatory cells and TCR-β(+) CD8αα IELs in Pim1(Tg) γc(KO) mice. Collectively, these results uncover distinct requirements for γc signaling between CD4(+) αβ T cells and all other T-lineage cells, and they identify Pim1 as a novel effector molecule sufficient to drive CD4(+) αβ T-cell development and survival in the absence of γc cytokine receptor signaling.
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http://dx.doi.org/10.1002/eji.201242686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7394666PMC
September 2013

Redox transformations of bis(2,2'-bipyridine)(1-methyl-1-pyridin-2-yl-ethylamine)ruthenium(II).

Inorg Chem 2008 Jun 7;47(12):5314-23. Epub 2008 May 7.

Department of Chemistry, Davidson College, Davidson, North Carolina 28035, USA.

The amineruthenium(II) complex Ru(bpy)2(mpea)2+ has been prepared by the direct reaction of 1-methyl-1-pyridin-2-yl-ethylamine (mpea) with Ru(bpy)2Cl2 in ethanol/water and isolated as the hexafluorophosphate salt. Electrochemical analysis of this complex shows that it undergoes sequential one-electron oxidations to an amidoruthenium(III) intermediate (E degrees' = 1.086 V vs NHE) and then to an amidoruthenium(IV) (E degrees' = 0.928 V) or imidoruthenium(IV) (E degrees' = 1.083 V) complex, depending upon the solution pH (pKa = 2.62 for the amidoruthenium(IV) species). At higher potentials ( Epa = 1.5 V in 1.0 M H2SO4), the amido- or imidoruthenium(IV) species is irreversibly oxidized to the corresponding nitrosoruthenium(II) complex. The mechanism for this transformation appears, on the basis of b3lyp/cpcm/cep-31g(d) computations, to proceed through an imidoruthenium(V) intermediate, which is rapidly attacked by water to yield a Ru(II)-bound hydroxylamine radical, which is readily oxidized and deprotonated to produce the nitrosoruthenium(II) complex. The nitrosoruthenium(II) complex is quantitatively reduced to the original [Ru(bpy)2(mpea)]2+ complex at relatively negative potentials ( Epc = -0.2 V in 1.0 M H2SO4).
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http://dx.doi.org/10.1021/ic800483gDOI Listing
June 2008