Biology subjects

Engle, S.

Publications and source records attributed to Engle, S..

3 recordsLinked to original sources

bioRxiv2022

Ablation of SAMD1 in Mice Causes Failure of Angiogenesis, Embryonic Lethality

Pathological retention of LDL in the intima is involved in atherosclerosis, although the retention mechanisms are not well-understood. Previously, we reported Sterile Alpha Motif Domain Containing 1 (SAMD1), a protein secreted by intimal smooth muscle cells in atherosclerotic lesions, appears to bind LDL in extracellular matrix around intimal cells. Fab-fragment inhibitors of apparently irreversible SAMD1/LDL binding reduced LDL retention in carotid injury models, but did not have a significant effect on early spontaneous lesion development. Our histology of mouse atherosclerosis models revealed extensive SAMD1 expression, possibly related to cell phenotype modulation and antigen presentation. Although the normal function of SAMD1 is unknown, it may have multiple epigenetic roles. For this report, we generated SAMD1-/-, SAMD1-/+, and SAMD1-/+ apoE-/- mice to further explore SAMD1s role in atherosclerosis. SAMD1 was found in tissues throughout the SAMD1+/+ and SAMD1-/+ embryos. Homozygous loss of SAMD1 was embryonic lethal: at embryonic day 14, organs were partially developed and/or degraded; heads and brains were malformed; no blood vessels were observed; red blood cells were scattered and pooled, primarily near the embryo surface; and cell death was occurring. Development appeared normal in heterozygous SAMD1 embryos, but postnatal genotyping showed a reduced ability to thrive. Growth of atherosclerotic lesions in SAMD1-/+ apoE-/- after 35 weeks was not significantly less than in mice SAMD1+/+ apoE-/- mice.

developmental biology↗

bioRxiv2021

CellMap: Characterizing the types and composition of iPSC-derived cells from RNA-seq data

Induced pluripotent stem cell (iPSC) derived cell types are increasingly employed as in vitro model systems for drug discovery. For these studies to be meaningful, it is important to understand the reproducibility of the iPSC-derived cultures and their similarity to equivalent endogenous cell types. Single-cell and single-nucleus RNA sequencing (RNA-seq) are useful to gain such understanding, but they are expensive and time consuming, while bulk RNA-seq data can be generated quicker and at lower cost. In silico cell type decomposition is an efficient, inexpensive, and convenient alternative that can leverage bulk RNA-seq to derive more fine-grained information about these cultures. We developed CellMap, a computational tool that derives cell type profiles from publicly available single-cell and single-nucleus datasets to infer cell types in bulk RNA-seq data from iPSC-derived cell lines.

bioinformatics↗

bioRxiv2021

An N-terminal Fusion Allele to Study Melanin Concentrating Hormone Receptor 1

Cilia on neurons play critical roles in both the development and function of the central nervous system (CNS). While it remains challenging to elucidate the precise roles for neuronal cilia, it is clear that a subset of G-protein-coupled receptors (GPCRs) preferentially localize to the cilia membrane. Further, ciliary GPCR signaling has been implicated in regulating a variety of behaviors. Melanin concentrating hormone receptor 1 (MCHR1), is a GPCR expressed centrally in rodents known to be enriched in cilia. Here we have used MCHR1 as a model ciliary GPCR to develop a strategy to fluorescently tag receptors expressed from the endogenous locus in vivo. Using CRISPR/Cas9, we inserted the coding sequence of the fluorescent protein mCherry into the N-terminus of Mchr1. Analysis of the fusion protein (mCherryMCHR1) revealed its localization to neuronal cilia in the CNS, across multiple developmental time points and in various regions of the adult brain. Our approach simultaneously produced fortuitous in/dels altering the Mchr1 start codon resulting in a new MCHR1 knockout line. Functional studies using electrophysiology show a significant alteration of synaptic strength in MCHR1 knockout mice. A reduction in strength is also detected in mice homozygous for the mCherry insertion, suggesting that while the strategy is useful for monitoring the receptor, activity could be altered. However, both lines should aid in studies of MCHR1 function and contribute to our understanding of MCHR1 signaling in the brain. Additionally, this approach could be expanded to aid in the study of other ciliary GPCRs.

neuroscience↗