Selected Grantee Publications
Cell-Type Memory in a Single-Cell Eukaryote Requires the Continuous Presence of a Specific Transcription Regulator
Lee et al., PNAS. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10214202/
Investigators studied the fundamental question and underlying mechanism of how a eukaryotic cell type can be stably maintained through many rounds of DNA replication and cell division in a fungal species where two different cell types (i.e., white and opaque) arise from the same genome. Investigators found that destruction of Wor1, the primary transcription activator of the opaque state, led opaque cells to irreversibly lose their memory and switch to the white-cell state within about 1 hour. This study demonstrates that the continuous presence of Wor1 is needed to maintain the opaque cell state. Data also suggested that a threshold concentration of Wor1 is needed to maintain the opaque state, indicating the importance of the transcription factor in maintaining cell-type memory. Supported by ORIP (S10OD028511), NIAID, and NIGMS.
High-Resolution Genomes of Multiple Xiphophorus Species Provide New Insights into Microevolution, Hybrid Incompatibility, and Epistasis
Lu et al., Genome Research. 2023.
https://pubmed.ncbi.nlm.nih.gov/37147111/
Existing Xiphophorus genome assemblies are not at the chromosomal level and are prone to sequence gaps, hindering advancement of evolutionary, comparative, and translational biomedical studies. Investigators assembled high-quality chromosome-level genome assemblies for three distantly related Xiphophorus species. They found that expanded gene families and positively selected genes associated with live bearing. Positively selected gene families were enriched in nonpolymorphic transposable elements, suggesting that dispersal has accompanied the evolution of the genes, possibly by incorporating new regulatory elements. The investigators also characterized interspecific polymorphisms, structural variants, and polymorphic transposable element insertions and assessed their association to interspecies hybridization-induced gene expression dysregulation related to specific disease states in humans. Supported by ORIP (R24OD011120, R24OD031467, R24OD011198) and NCI.
Resolution of Structural Variation in Diverse Mouse Genomes Reveals Chromatin Remodeling due to Transposable Elements
Ferraj et al., Cell Genomics. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10203049/
Diverse inbred mouse strains are important biomedical research models, yet genome characterization of many strains is fundamentally lacking in comparison with humans. Here, investigators used long-read whole genome sequencing to assemble the genomes of 20 diverse inbred laboratory strains of mice. From whole-genome comparisons, they generated a sequence-resolved callset of 413,758 structural variants. These data are presented as a comprehensive resource that can be used for future genomic studies, aid in modeling and studying the effects of genetic variation, and enhance genotype-to-phenotype research. Supported by ORIP (R24OD021325), NCI, NIGMS, and NHGRI.
Topologically Associating Domain Boundaries Are Required for Normal Genome Function
Rajderkar et al., Communications Biology. 2023.
https://www.nature.com/articles/s42003-023-04819-w
Eukaryotic genomes fold into topologically associating domains (TADs), sub-megabase-scale chromatin segments characterized by high intra-domain chromatin contact frequency. Investigators selected eight independent TAD boundaries in the vicinity of genes active during embryonic development, individually deleted these boundaries from the mouse genome, and systematically examined the consequences on survival, genome organization, gene expression, and development. Results of the studies demonstrate the importance of TAD boundary sequences for in vivo genome function and reinforce the critical need to consider the potential pathogenicity of deletions affecting TAD boundaries in clinical genetics screening. Supported by ORIP (UM1OD023221), NIGMS, and NHGRI.
Identification of a Heterogeneous and Dynamic Ciliome during Embryonic Development and Cell Differentiation
Elliott et al., Development. 2023.
Ciliopathies are a class of diseases that arise when the structure or function of the cilium is compromised. To definitively determine the extent of heterogeneity within the ciliome, investigators compared the ciliomes of six distinct embryonic domains. The data comprehensively revealed that about 30% of the ciliome is differentially expressed across analyzed tissues in the developing embryo. Furthermore, upregulation of numerous ciliary genes correlated with osteogenic cell-fate decisions, suggesting that changes in the ciliome contribute to distinct functions of cell types in vertebrate species. Supported by ORIP (UM1OD023222), NIDCR, and NIGMS.
The Incompetence of Mosquitoes—Can Zika Virus Be Adapted to Infect Culex tarsalis Cells?
Gallichotte et al., mSphere . 2023.
Zika virus (ZIKV) is transmitted between humans by Aedes aegypti mosquitoes. However, the 2015 to 2017 outbreak raised questions regarding the role of Culex species mosquitoes in transmission. Investigators attempted to adapt ZIKV to C. tarsalis by serially passaging the virus on cocultured A. aegypti and C. tarsalis cells to identify viral determinants of species specificity. Next-generation sequencing of cocultured virus passages revealed variants of interest that were engineered into nine recombinant viruses. None of these viruses showed increased infection of Culex cells or mosquitoes. Thus, although ZIKV might infect Culex mosquitoes occasionally, Aedes mosquitoes likely drive transmission and human risk. Supported by ORIP (T32OD010437) and NIAID.
Leukocyte Tyrosine Kinase (Ltk) Is the Mendelian Determinant of the Axolotl Melanoid Color Variant
Kabangu et al., Genes. 2023.
https://www.mdpi.com/2073-4425/14/4/904
The diversity of color patterns among amphibians is largely explained by the differentiation of a few pigment cell types during development. Mexican axolotls have a variety of color phenotypes, from leucistic to highly melanistic. The melanoid axolotl is a Mendelian variant characterized by large numbers of melanophores, fewer xanthophores, and no iridophores. Studies of melanoid were influential in developing the single-origin hypothesis of pigment cell development, proposing that all three pigment cell types derive from a common progenitor cell, with pigment metabolites playing potential roles in directing the development of organelles that define different pigment cell types. Xanthine dehydrogenase (XDH) activity was identified as a mechanism for the permissive differentiation of melanophores at the expense of xanthophores and iridophores. The authors used bulked segregant RNA-Seq (including a region on chromosome 14q) to screen the axolotl genome for melanoid candidate genes and identify the associated locus. The region 14q contains gephyrin (Gphn), an enzyme that catalyzes the synthesis of the molybdenum cofactor that is required for XDH activity, and Ltk, a cell surface signaling receptor required for iridophore differentiation in zebrafish. Wild-type Ltk crispants present similar pigment phenotypes to melanoid, strongly implicating Ltk as the melanoid locus. The results support the idea of direct fate specification of pigment cells, as well as the single-origin hypothesis of pigment cell development. Supported by ORIP (P40OD019794, R24OD010435, R24OD021479).
Effect of the Snake Venom Component Crotamine on Lymphatic Endothelial Cell Responses and Lymph Transport
Si et al., Microcirculation. 2023.
https://onlinelibrary.wiley.com/doi/10.1111/micc.12775
The pathology of snake envenomation is closely tied to the severity of edema in the tissue surrounding the area of the bite. This study focused on one of the most abundant venom components in North American viper venom, crotamine, and the effects it has on the cells and function of the lymphatic system. The authors found that genes that encode targets of crotamine are highly present in lymphatic tissues and cells and that there is a differential distribution of those genes that correlates with phasic contractile activity. They found that crotamine potentiates calcium flux in human dermal lymphatic endothelial cells in response to stimulation with histamine and shear stress—but not alone—and that it alters the production of nitric oxide in response to shear, as well as changes the level of F-actin polymerization of those same cells. Crotamine alters lymphatic transport of large molecular weight tracers to local lymph nodes and is deposited within the node, mostly in the immediate subcapsular region. Results suggest that snake venom components may have an impact on the function of the lymphatic system and provide new targets for improved therapeutics to treat snakebites. Supported by ORIP (P40OD010960).
Longitudinal Characterization of Circulating Extracellular Vesicles and Small RNA During Simian Immunodeficiency Virus Infection and Antiretroviral Therapy
Huang et al., AIDS. 2023.
https://www.doi.org/10.1097/QAD.0000000000003487
Antiretroviral therapy is effective for controlling HIV infection but does not fully prevent early aging disorders or serious non-AIDS events among people with HIV. Using pigtail and rhesus macaques (sex not specified), researchers profiled extracellular vesicle small RNAs during different phases of simian immunodeficiency virus infection to explore the potential relationship between extracellular vesicle–associated small RNAs and the infection process. They reported that average particle counts correlated with infection, but the trend could not be explained fully by virions. These findings raise new questions about the distribution of extracellular vesicle RNAs in HIV latent infection. Supported by ORIP (U42OD013117), NIDA, NIMH, NIAID, NCI, and NINDS.
A Live Dengue Virus Vaccine Carrying a Chimeric Envelope Glycoprotein Elicits Dual DENV2–DENV4 Serotype-Specific Immunity
Young et al., Nature Communications. 2023.
https://pubmed.ncbi.nlm.nih.gov/36914616/
Dengue vaccine development is challenging because some virus-specific antibodies are protective, whereas others are implicated in enhanced viral replication and more severe disease. Current dengue tetravalent vaccines contain four live attenuated serotypes formulated to induce balanced protective immunity. To simplify live-virus vaccine design, investigators identified co-evolutionary constraints inherent in flavivirus virion assembly. They found that the chimeric virus replicated efficiently in vitro and in vivo and that a single inoculation induced type-specific neutralizing antibodies in male macaques. These findings can be applied to the development of bivalent live dengue vaccines that induce independent immunity to multiple serotypes. Supported by ORIP (P40OD012217) and NIAID.