Biology subjects

Jacobson, A.

Publications and source records attributed to Jacobson, A..

24 records · Page 2Linked to original sources

bioRxiv2020

Acoustogenetic Control of CAR T Cells via Focused Ultrasound

Optogenetics can control specific molecular events in living systems, but the penetration depth of light is typically limited at hundreds of micrometers. Focused ultrasound (FUS), on the other hand, can deliver energy safely and noninvasively into tissues at depths of centimeters. Here we have developed an acoustogenetic approach using short-pulsed FUS to remotely and directly control the genetics and cellular functions of engineered mammalian cells for therapeutic purposes. We applied this acoustogenetic approach to control chimeric antigen receptor (CAR) T cells with high spatiotemporal precision, aiming to mitigate the potentially lethal "on-target off-tumor" effects of CAR T cell therapy. We first verified the controllability of our acoustogenetic CAR T cells in recognizing and killing tumor cells in vitro, and then applied this approach in vivo to suppress tumor growth of both lymphoma and prostate cancers. The results indicate that FUS-based acoustogenetics can allow the noninvasive and remote activation, without any exogenous cofactor, of different types of CAR T cells for cancer therapeutics.

bioengineering↗

bioRxiv2019

Nonsense suppression position effect implicates poly(A)-binding protein in the regulation of translation termination

Readthrough of translation termination codons, also known as nonsense suppression, is a relatively inefficient process mediated by ribosomal A site recognition and insertion of near-cognate tRNAs. Multiple factors influence readthrough efficiency, including nonsense codon specificity and context. To determine whether nonsense codon position in a gene influences the extent of readthrough, we generated a series of LUC nonsense alleles and quantitated both readthrough and termination efficiencies at each nonsense codon in yeast cells lacking nonsense-mediated mRNA decay (NMD) activity. Readthrough efficiency for premature termination codons (PTCs) manifested a marked dependence on PTC proximity to the mRNA 3-end, decreasing progressively across the LUC ORF but increasing with 3-UTR lengthening. These effects were eliminated, and translation termination efficiency decreased considerably, in cells harboring pab1 mutations. Our results support a critical role for poly(A)-binding protein in the regulation of translation termination and suggest that inefficient termination is the trigger for NMD.

molecular biology↗

bioRxiv2019

MicroRNA miR-7 regulates synthesis and secretion of insulin-like peptides

The insulin/IGF pathway is essential for linking nutritional status to growth and metabolism. MicroRNAs (miRNAs) are short RNAs that are players in the regulation of this process. The miRNA miR-7 shows highly conserved expression in insulin-producing cells across the animal kingdom, however, its conserved functions in regulation of insulin-like peptides (ILPs) remains unknown. Using Drosophila as a model, we demonstrate that miR-7 limits ILP availability by inhibiting its production and secretion. Increasing miR-7 alters body growth and metabolism in an ILP-dependent manner, elevating circulating sugars and total body triglycerides, while decreasing animal growth. These effects are not due to direct targeting of ILP mRNA, but instead arise through alternate targets that affect the function of ILP-producing cells. The Drosophila F-actin capping protein, CPA, is a direct target of miR-7, and knockdown of CPA in IPCs phenocopies the effects of miR-7 on ILP secretion. This regulation of CPA is conserved in mammals, with the mouse ortholog Capza1 also targeted by miR-7 in {beta}-islet cells. Taken together, these results support a role for miR-7 regulation of an actin capping protein in insulin regulation, and highlight a conserved mechanism of action for an evolutionarily ancient microRNA.\n\nDisclosure StatementPA, JB, AJ and RWC have nothing to declare. JJC is an employee of Sg2, LLC, a healthcare consulting company.

physiology↗

bioRxiv2019

Gut-innervating nociceptor neurons protect against enteric infection by modulating the microbiota and Peyer’s patch microfold cells

Gut-innervating nociceptor sensory neurons respond to noxious/tissue-damaging stimuli by initiating protective responses and releasing mediators that regulate tissue inflammation, gastrointestinal secretion, and motility. The role of nociceptors in host defense against enteric pathogens is unclear. Here, we found that gut-extrinsic nociceptor neurons are critical in protecting the host against Salmonella typhimurium (STm) infection. Nociceptors responded to STm by releasing the neuropeptide calcitonin gene-related peptide (CGRP). Targeted depletion of Nav1.8 and TRPV1 neurons from gut-extrinsic dorsal root ganglia and vagal ganglia increased STm colonization, invasion, and dissemination. Nociceptors regulated the gut microbiota at homeostasis, specifically segmented filamentous bacteria (SFB) levels in the ileum, which protected against STm by colonization resistance. Nociceptors also regulated the density of microfold epithelial cells in the Peyers patch via CGRP to limit points of entry for STm invasion into host tissues. Understanding how host sensory neurons crosstalk with pathogenic bacteria may impact treatments for enteric infections.\n\nHIGHLIGHTSO_LINav1.8 and TRPV1 nociceptors defend against Salmonella typhimurium (STm) infection\nC_LIO_LINociceptors shape the gut microbiota and SFB levels which resist pathogen colonization\nC_LIO_LINociceptors suppress Peyers patch microfold cell density to limit pathogen invasion\nC_LIO_LINeurons sense STm and release CGRP to modulate microfold cells and host defense\nC_LI

immunology↗

bioRxiv2018

General decapping activators target different subsets of inefficiently translated mRNAs

The Dcp1-Dcp2 decapping enzyme and the decapping activators Pat1, Dhh1, and Lsm1 regulate mRNA decapping, but their mechanistic integration is unknown. We analyzed the gene expression consequences of deleting PAT1, LSM1, or DHH1, or the DCP2 C-terminal domain, and found that: i) the Dcp2 C-terminal domain is an effector of both negative and positive regulation; ii) rather than being global activators of decapping, Pat1, Lsm1, and Dhh1 directly target specific subsets of yeast mRNAs and loss of the functions of each of these factors has substantial indirect consequences for genome-wide mRNA expression; and iii) transcripts targeted by Pat1, Lsm1, and Dhh1 exhibit only partial overlap, are generally translated inefficiently, and, as expected, are targeted to decapping-dependent decay. Our results define the roles of Pat1, Lsm1, and Dhh1 in decapping of general mRNAs and suggest that these factors may monitor mRNA translation and target unique features of individual mRNAs.

molecular biology↗

bioRxiv2018

A new in vitro assay measuring direct interaction of nonsense suppressors with the eukaryotic protein synthesis machinery

Nonsense suppressors (NonSups) induce \"readthrough\", i.e., the selection of near cognate tRNAs at premature termination codons and insertion of the corresponding amino acid into nascent polypeptide. Prior readthrough measurements utilized contexts in which NonSups can promote readthrough directly, by binding to one or more of the components of the protein synthesis machinery, or indirectly, by several other mechanisms. Here we utilize a new, highly-purified in vitro assay to measure exclusively direct nonsense suppressor-induced readthrough. Of 16 NonSups tested, 12 display direct readthrough, with results suggesting that such NonSups act by at least two different mechanisms. In preliminary work we demonstrate the potential of single molecule fluorescence energy transfer measurements to elucidate mechanisms of NonSup-induced direct readthrough, which will aid efforts to identify NonSups having improved clinical efficacy.\n\nTable of Contents artwork\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC=\"FIGDIR/small/330506_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (18K):\norg.highwire.dtl.DTLVardef@a548dborg.highwire.dtl.DTLVardef@15237bcorg.highwire.dtl.DTLVardef@c93d3forg.highwire.dtl.DTLVardef@1d40e2c_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗