Biomedical subjects

Thomas F Vogt

Publications and source records attributed to Thomas F Vogt.

7 recordsLinked to original sources

PubMed2005

Inhibition of retinal and choroidal neovascularization by a novel KDR kinase inhibitor.

PURPOSE: Inhibition of vascular endothelial growth factor (VEGF) signaling has shown great promise for the treatment of ocular neovascular disease. Current anti-VEGF therapies in late-stage development, while efficacious, require dosing by frequent intravitreal injections that are inconvenient to patients. VEGF signaling inhibitors that demonstrate more convenient dosing regimens could lead to the improved treatment of neovascular diseases such as wet age related macular degeneration (AMD) and proliferative diabetic retinopathy (PDR). Here we describe the assessment of a KDR (VEGFR2) kinase inhibitor in two well-established models of ocular neovascularization following oral administration. METHODS: A novel KDR kinase inhibitor was dosed by oral gavage for 12 days at 0, 10, 30, or 100 mg/kg in an adult male Brown Norway rat laser induced choroidal neovascularization (CNV) model. The areas of CNV lesions were quantitated by fluorescence image analysis of FITC-dextran perfused animals. The kinase inhibitor was also assessed in a rat oxygen induced retinopathy (OIR) model in which neonatal rats were placed in an oxygen chamber that delivered alternating 24 h cycles of 50% and 10% oxygen for 14 days. After 14 days of oxygen treatment, the animals were returned to room air and dosed orally for 7 days with 0, 10, or 30 mg/kg kinase inhibitor. The extent of retinal neovascularization was assessed by counting pre-retinal neovascular nuclei on histological sections. RESULTS: At doses of 100 mg/kg, the KDR kinase inhibitor resulted in a 98% reduction in lesion size in the rat CNV model. 30 mg/kg doses of the inhibitor showed a 70% and 80% reduction in lesion size in the laser CNV and OIR models, respectively. CONCLUSIONS: Oral dosing of the described KDR kinase inhibitor effectively inhibits neovascularization in two well-established animal models of ocular neovascularization. These data suggest that compounds of this class may prove to be useful for the treatment of a variety of ocular neovascular diseases using a convenient oral dosing regimen.

Administration, Oral↗

PubMed2004

Pleiotrophin is an important regulator of the renin-angiotensin system in mouse aorta.

To better understand the phenotype of pleiotrophin (PTN the protein, Ptn the gene) genetically deficient mice (Ptn -/-), we compared the transcriptional profiles of aortae obtained from Ptn -/- and wild type (WT, Ptn +/+) mice using a 14,400 gene microarray chip (Affymetrix) and confirmed the analysis of relevant genes by real time RT-PCR. We found striking alterations in expression levels of different genes of the renin-angiotensin system of Ptn -/- mice relative to WT (Ptn +/+) mice. The mRNA levels of the angiotensin converting enzyme (ACE) were significantly decreased in Ptn -/- mice whereas the mRNA levels of the angiotensin II type 1 (AT1) and angiotensin II type 2 (AT2) receptors were significantly increased in Ptn -/- mice when they were compared with mRNA levels in WT (Ptn +/+) mice aortae. These data demonstrate for the first time that the levels of expression of the Ptn gene markedly influence expression levels of the genes encoding the key proteins of the renin-angiotensin system in mouse aorta and suggest the tentative conclusion that levels of Ptn gene expression have the potential to critically regulate the downstream activities of angiotensin II, through the regulation of its synthesis by ACE and its receptor mediated functions through regulation of both the AT1 and AT2 receptors.

Animals↗

PubMed2004

Pleiotrophin is a major regulator of the catecholamine biosynthesis pathway in mouse aorta.

To better understand the phenotype of pleiotrophin (PTN the protein, Ptn the gene) genetically deficient mice (Ptn -/-), we compared the transcriptional profiles of aortae obtained from Ptn -/- and wild type (WT, Ptn +/+) mice using a 14,400 gene microarray chip (Affymetrix) and confirmed the analysis of relevant genes by real time RT-PCR. We identified a dramatic upregulation of expression of tyrosine hydroxylase (TH), DOPA decarboxylase, and dopamine beta-hydroxylase in aortae of Ptn -/- mice in comparison with WT (Ptn +/+) mice. In contrast, transcripts of phenylethanolamine-N-methyltransferase, the enzyme catalyzing the conversion of norepinephrine into epinephrine, were not detected in aortae in either mouse strain. These findings suggest that Ptn gene expression has a critical role in determining the levels of expression of the enzymes of catecholamine biosynthesis in aorta and through this mechanism, PTN may regulate levels of endogenous catecholamine synthesis and potentially the vascular tone of aorta.

Animals↗

PubMed2004

The knockout mouse project.

Mouse knockout technology provides a powerful means of elucidating gene function in vivo, and a publicly available genome-wide collection of mouse knockouts would be significantly enabling for biomedical discovery. To date, published knockouts exist for only about 10% of mouse genes. Furthermore, many of these are limited in utility because they have not been made or phenotyped in standardized ways, and many are not freely available to researchers. It is time to harness new technologies and efficiencies of production to mount a high-throughput international effort to produce and phenotype knockouts for all mouse genes, and place these resources into the public domain.

Alleles↗

PubMed2003

Molecular genetic analysis of the glycosyltransferase Fringe in Drosophila.

Fringe proteins are beta1,3-N-acetylglucosaminyltransferases that modulate signaling through Notch receptors by modifying O-linked fucose on epidermal growth factor domains. Fringe is highly conserved, and comparison among 18 different Fringe proteins from 11 different species identifies a core set of 84 amino acids that are identical among all Fringes. Fringe is only distantly related to other glycosyltransferases, but analysis of the predicted Drosophila proteome identifies a set of four sequence motifs shared among Fringe and other putative beta1,3-glycosyltransferases. To gain functional insight into these conserved sequences, we genetically and molecularly characterized 14 point mutations in Drosophila fringe. Most nonsense mutations act as recessive antimorphs, raising the possibility that Fringe may function as a dimer. Missense mutations identify two distinct motifs that are conserved among beta1,3-glycosyltransferases, and that can be modeled onto key motifs in the crystallographic structures of bovine beta1,4-galactosyltransferase 1 and human glucuronyltransferase I. Other missense mutations map to amino acids that are conserved among Fringe proteins, but not among other glycosyltransferases, and thus may identify structural motifs that are required for unique aspects of Fringe activity.

Amino Acid Sequence↗

PubMed2002

Mutations in Mcoln3 associated with deafness and pigmentation defects in varitint-waddler (Va) mice.

Deafness in spontaneously occurring mouse mutants is often associated with defects in cochlea sensory hair cells, opening an avenue to systematically identify genes critical for hair cell structure and function. The classical semidominant mouse mutant varitint-waddler (Va) exhibits early-onset hearing loss, vestibular defects, pigmentation abnormalities, and perinatal lethality. A second allele, Va(J), which arose in a cross segregating for Va, shows a less severe phenotype. By using a positional cloning strategy, we identify two additional members of the mucolipin gene family (Mcoln2 and Mcoln3) in the 350-kb Va(J) minimal interval and provide evidence for Mcoln3 as the gene mutated in varitint-waddler. Mcoln3 encodes a putative six-transmembrane-domain protein with sequence and motif similarities to the family of nonselective transient-receptor-potential (TRP) ion channels. In the Va allele an Ala419Pro substitution occurs in the fifth transmembrane domain of Mcoln3, and in Va(J), a second sequence alteration (Ile362Thr) occurring in cis partially rescues the Va allele. Mcoln3 localizes to cytoplasmic compartments of hair cells and plasma membrane of stereocilia. Hair cell defects are apparent by embryonic day 17.5, assigning Mcoln3 an essential role during early hair cell maturation. Our data suggest that Mcoln3 is involved in ion homeostasis and acts cell-autonomously. Hence, we identify a molecular link between hair cell physiology and melanocyte function. Last, MCOLN2 and MCOLN3 are candidate genes for hereditary and/or sporadic forms of neurosensory disorders in humans.

Amino Acid Sequence↗

PubMed2002

Clock regulatory elements control cyclic expression of Lunatic fringe during somitogenesis.

Somitogenesis requires a segmentation clock and Notch signaling. Lunatic fringe (Lfng) expression in the presomitic mesoderm (PSM) cycles in the posterior PSM, is refined in the segmenting somite to the rostral compartment, and is required for segmentation. We identify distinct cis-acting regulatory elements for each aspect of Lfng expression. Fringe clock element 1 (FCE1) represents a conserved 110 bp region that is necessary to direct cyclic Lfng RNA expression in the posterior PSM. Mutational analysis of E boxes within FCE1 indicates a potential interplay of positive and negative transcriptional regulation by cyclically expressed bHLH proteins. A separable Lfng regulatory region directs expression to the prospective rostral aspect of the condensing somite. These independent Lfng regulatory cassettes advance a molecular framework for deciphering somite segmentation.

5' Flanking Region↗