Biomedical subjects

Jennifer L Johnson

Publications and source records attributed to Jennifer L Johnson.

7 recordsLinked to original sources

PubMed2026

Synaptic Proteome Divergence in the Prefrontal Cortex of Tame and Aggressive Red Foxes (Vulpes vulpes).

The biological mechanisms behind aggressive and affiliative behaviors are difficult to pinpoint. In the Farm-Fox Experiment, conventional foxes were selectively bred since 1959 in two different directions, one for tame and another for aggressive response to humans. The distinct differences in social behavior of tame, aggressive, and conventional populations are genetically based and the three populations live in conditions that control for factors that could impact social reactions, such as environment and social experiences. Genomic and transcriptomic studies of genetic differences among the fox populations have highlighted genes involved in synaptic processes in the prefrontal cortex. To investigate how the synaptic mechanisms differ between the three fox populations, synaptosomes were isolated from prefrontal and premotor cortex extracts of sixteen female foxes. Tandem mass tags with liquid chromatography tandem mass spectrometry (LC-MS) were used to identify and quantify the relative abundance of the proteins. The results were sorted into protein groups and compared between populations using a limma analysis to determine proteins with differential expression (DE). In the tame versus aggressive comparison, 174 protein groups were found to be DE, while only five were found in the conventional versus aggressive comparison. Most DE protein groups had lower fold expression in the aggressive population compared to tame and aggressive populations. ADGRB2 was found to be the most DE protein group, with 11-fold higher expression in aggressive foxes than in tame foxes. ADGRB2 was previously shown to affect depression-like behavior in mice and is involved in the vascular endothelial growth factor signaling pathway, that is known to influence neurogenesis. Enrichment analyses on the DE protein groups found gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were enriched in the tame versus aggressive comparison, including multiple, highly enriched terms involving ribosome and translation. Local translation at synapses plays an important role in synaptic plasticity and, as a result, can profoundly influence behavior. This study highlighted potential mechanisms that could underly the behavioral differences between tame and aggressive foxes.

Journal Article↗

PubMed2003

Comparative analysis, gene organization and expression of canine TCTE1L.

The murine t-complex-associated testis-expressed 1-like gene (TCTE1L) of the dog was cloned, characterized, and compared to the human ortholog. The characterized region of cDNA includes 351 bp of coding sequence which encodes a protein of 116 amino acids. The canine gene, spanning about 8.5 kb sequence, consists of 5 exons, with the initiation and stop codons found in the first and last exons, respectively. The comparative analyses reveal the evolutionarily conserved exonic and intronic regions, as well as gene flanking sequences. A 2.1 kb transcript was ubiquitously expressed in all the tissues examined, and secondarily down-expressed in the retinas of two non-allelic forms of inherited retinal diseases.

Amino Acid Sequence↗

PubMed2002

JFC1 is transcriptionally activated by nuclear factor-kappaB and up-regulated by tumour necrosis factor alpha in prostate carcinoma cells.

The human promoter region of JFC1, a phosphatidylinositol 3,4,5-trisphosphate binding ATPase, was isolated by amplification of a 549 bp region upstream of the jfc1 gene by the use of a double-PCR system. By primer extension analysis we mapped the transcription initiation site at nucleotide -321 relative to the translation start site. Putative regulatory elements were identified in the jfc1 TATA-less promoter, including three consensus sites for nuclear factor-kappaB (NF-kappaB). We analysed the three putative NF-kappaB binding sites by gel retardation and supershift assays. Each of the putative NF-kappaB sites interacted specifically with recombinant NF-kappaB p50, and the complexes co-migrated with those formed by the NF-kappaB consensus sequence and p50. An antibody to p50 generated a supershifted complex for these NF-kappaB sites. These sites formed specific complexes with nuclear proteins from tumour necrosis factor alpha (TNFalpha)-treated WEHI 231 cells, which were supershifted with antibodies against p50 and p65. The jfc1 promoter was transcriptionally active in various cell lines, as determined by luciferase reporter assays following transfection with a jfc1 promoter luciferase vector. Co-transfection with NF-kappaB expression vectors or stimulation with TNFalpha resulted in significant transactivation of the jfc1 promoter construct, although transactivation of a mutated jfc1 promoter was negligible. The expression of a dominant negative IkappaB (inhibitor kappaB) decreased basal jfc1 promoter activity. The cell lines PC-3, LNCaP and DU-145, but not Epstein-Barr virus-transformed lymphocytes, showed a dramatic increase in the expression of JFC1 after treatment with TNFalpha, suggesting that transcriptional activation of JFC1 by the TNFalpha/NF-kappaB pathway is significant in prostate carcinoma cell lines.

Base Sequence↗

PubMed2002

The C2A domain of JFC1 binds to 3'-phosphorylated phosphoinositides and directs plasma membrane association in living cells.

Phosphatidylinositol 3-kinase products play a central role in the regulation of several intracellular pathways via adaptor proteins that share the ability to bind to 3'-phosphoinositides with high affinity and specificity. JFC1 is a C2 domain-containing protein involved in cellular trafficking that has been shown to bind 3'-phosphoinositides in vitro. In this work, we demonstrate that the C2A domain of JFC1 is the module responsible for its binding to the plasma membrane via 3'-phosphoinositides in vivo. We show that the C2A domain of JFC1 is the only domain present in this protein that localizes to the plasma membrane in living cells. Moreover, the C2A domain of JFC1 binds 3'-phosphoinositides in vitro with similar specificity as that described for full-length JFC1, suggesting that the domain mediates the specific membrane localization of the full-length protein. Furthermore, the C2A domain of JFC1 colocalized with the pleckstrin homology domain of Akt in vivo, and both the JFC1 C2A domain and the full-length JFC1 dissociated from the membrane in the presence of PI 3-kinase specific inhibitors. We also show that the association of the C2A domain to the membrane is modulated by calcium. From these results we analyze possible mechanisms for the role of JFC1 in cellular trafficking.

3T3 Cells↗

PubMed2002

Different RPGR exon ORF15 mutations in Canids provide insights into photoreceptor cell degeneration.

The canine disease, X-linked progressive retinal atrophy (XLPRA), is similar to human RP3, an X-linked form of retinitis pigmentosa, and maps to the same region in the X chromosome. Analysis of the physical map of the XLPRA and RP3 intervals shows a high degree of conservation in terms of genes and their order. We have found different mutations in exon ORF15 of the RPGR gene in two distinct mutant dog strains (XLPRA1, XLPRA2). Microdeletions resulting in a premature stop or a frameshift mutation result in very different retinal phenotypes, which are allele-specific and consistent for each mutation. The phenotype associated with the frameshift mutation in XLPRA2 is very severe and manifests during retinal development; the phenotype resulting from the XLPRA1 nonsense mutation is expressed only after normal photoreceptor morphogenesis. Splicing of RPGR mRNA transcripts in retina is complex, and either exon ORF15 or exon 19 can be a terminal exon. The retina-predominant transcript contains ORF15 as a terminal exon, and is expressed in normal and mutant retinas. The frameshift mutation dramatically alters the deduced amino acid sequence, and the protein aggregates in the endoplasmic reticulum of transfected cells. The cellular and molecular results in the two canine RPGR exon ORF15 mutations have implications for understanding the phenotypic variability found in human RP3 families that carry similar mutations.

Animals↗

PubMed2002

The hydrolysis of bimatoprost in corneal tissue generates a potent prostanoid FP receptor agonist.

Using human and bovine corneal tissue, we investigated the in vitro metabolism of bimatoprost (17-phenyl-18,19,20-trinor-prostaglandin F(2alpha) ethyl amide, Lumigan (Allergan, Inc, Irvine, CA). Enzymatic amidase activity, which converts bimatoprost to the corresponding prostaglandin carboxylic acid, was found to be present in corneal tissue from both species. Using HPLC and mass spectrometry for analyses, conversion of bimatoprost to 17-phenyl-18,19,20-trinor prostaglandin F(2alpha) continued for at least 24 hours after excision of the cornea, with a conversion rate of approximately 25 microg/24 hours. This hydrolysis product is identical to the free acid of latanoprost with the exception of a double, rather than a single, bond at the carbon 13-14 position. Assuming that this conversion also occurs in vivo at a similar rate, this hydrolysis product may account for the reduction of intraocular pressure occurring in patients treated with bimatoprost.

Amides↗

PubMedDate not supplied

Alternative field methods for measuring hearing protector performance.

In comparison with the mandatory noise reduction rating (NRR) testing of every hearing protector sold in the United States, real-world tests of hearing protector attenuation are scarce. This study evaluated data from three potential field-test methods as compared with the subject-fit data from Method B of ANSI S12.6-1997 for the E.A.R(R) Express trade mark Pod Plug trade mark. The new field-test methods were the FitCheck headphone (FCH) method, FitCheck in sound field (FCSF) method, and bone-conduction loudness balance (BCLB) method, all of which can be administered in small single-person audiometric booths such as are commonly found in industry. Twenty normal-hearing and audiometrically competent subjects naive to hearing protector use were tested with the laboratory and the three field-test methods in a repeated-measures design. Repeated-measures models with structured covariance matrices were used to analyze the data. Significant effects were found for method, frequency, and first-order frequency-by-gender and frequency-by-method interactions. These effects and interactions were expected given the different psychophysical tasks. The FCSF and BCLB methods provided attenuations that were not significantly different from those found with Method B. Although the attenuations measured for the FCH method were statistically different (greater) than the attenuations from the other methods, the differences were within the magnitude of acceptable test-retest audiometric variability. The results suggest that the FCH and FCSF methods were both feasible and reliable methods for field testing. The FCH method is limited to testing earplugs, and the FCSF requires additional equipment to outfit the test booth, but could be used for testing all types of protectors.

Adolescent↗