Vincent Groppi | University of Michigan (original) (raw)

Papers by Vincent Groppi

Development, 1991

TIMP (tissue inhibitor of metalloproteinase) is a glycoprotein inhibitor of metalloproteinases th... more TIMP (tissue inhibitor of metalloproteinase) is a glycoprotein inhibitor of metalloproteinases that we hypothesize to be involved in the tissue remodeling that occurs during each hair growth cycle. We examined this hypothesis by studying the expression of TIMP at selected times during a single hair cycle using T1MP– lacZ transgenic mice to localize TIMP gene activity in the hair follicle. TIMP gene induction was visualized by staining mouse back skin for β-galactosidase (β-gal) activity. Paraffin sections were analyzed for the localization of TIMP expression. TIMP gene activation appears in hair follicles only during the mid-anagen (the growing stage of the hair cycle) primarily in Henle’s layer of the inner root sheath. Some expression of TIMP is also seen in a few connective tissue cells, in the sebaceous gland and in cells at the proximity of the dermal papilla cells in catagen (regressing) and telogen (resting) follicles. These results are consistent with a role for TIMP in cycl...

Journal of Biological Chemistry, 1983

Extracts of a mutant 549 lymphoma cell line, termed K30a, hydrolyze cAMP and cGMP at rates much f... more Extracts of a mutant 549 lymphoma cell line, termed K30a, hydrolyze cAMP and cGMP at rates much faster than do wild type 549 extracts. This elevated phosphodiesterase activity, called K-PDE, elutes as a single peak of activity on DEAE-cellulose columns (Brothers,

Journal of Medicinal Chemistry, 2019

Journal of medicinal chemistry, Jan 27, 2017

Hearing loss is a major public health concern with no pharmaceutical intervention for hearing pro... more Hearing loss is a major public health concern with no pharmaceutical intervention for hearing protection or restoration. Using zebrafish neuromast hair cells, a robust model for mammalian auditory and vestibular hair cells, we identified a urea-thiophene carboxamide, 1 (ORC-001), as protective against aminoglycoside antibiotic (AGA)-induced hair cell death. The 50% protection (HC50) concentration conferred by 1 is 3.2 μM with protection against 200 μM neomycin approaching 100%. Compound 1 was sufficiently safe and drug-like to validate otoprotection in an in vivo rat hearing loss model. We explored the structure-activity relationship (SAR) of this compound series to improve otoprotective potency, improve pharmacokinetic properties and eliminate off-target activity. We present the optimization of 1 to yield 90 (ORC-13661). Compound 90 protects mechanosensory hair cells with HC50 of 120 nM and demonstrates 100% protection in the zebrafish assay and superior physiochemical, pharmacokin...

Molecular and Cellular Biology, 1988

Platelet-derived growth factor (PDGF), the calcium ionophore A23187, and the tumor promoter phorb... more Platelet-derived growth factor (PDGF), the calcium ionophore A23187, and the tumor promoter phorbol myristate acetate stimulated c-fos mRNA levels in control NIH 3T3 cells. However, NIH 3T3 cells transformed by EJ-ras DNA transfection, which have diminished PDGF-stimulated phospholipase C activity, showed a 95% reduction in PDGF-stimulated c-fos mRNA levels. The responses to A23187 and phorbol myristate acetate were also attenuated, but not as severely as the PDGF-mediated induction. The reduction in PDGF-stimulated c-fos induction did not appear to be a general result of cellular transformation, since src-transformed NIH 3T3 cells displayed a strong PDGF-stimulated c-fos induction. Despite the reduction in PDGF-stimulated c-fos induction, EJ-ras-transformed cells still responded mitogenically to PDGF. These data suggest that the magnitude of c-fos induction cannot be directly correlated with PDGF-stimulated mitogenesis in EJ-ras-transformed NIH 3T3 cells.

Molecular and Cellular Biology, 1984

The inhibition of protein synthesis in exponentially growing S49 cells leads to a specific fivefo... more The inhibition of protein synthesis in exponentially growing S49 cells leads to a specific fivefold increase in histone mRNA in 30 min. The rate of transcription of histone mRNA, measured in intact or digitonin-permeabilized cells, is increased slightly, if at all, by cycloheximide inhibition of protein synthesis. Both approach-to-equilibrium labeling and pulse-chase experiments show that cycloheximide prolongs histone mRNA half-life from approximately 30 min to greater than 2 h. Histone mRNA made before the addition of cycloheximide becomes stable after the inhibition of protein synthesis, whereas removal of the inhibitor is followed by rapid degradation of histone mRNA. This suggests that the increased stability of histone mRNA during inhibition of protein synthesis results not from alteration of the structure of the mRNA, but from the loss of an activity in the cell which regulates histone mRNA turnover.

The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 27, 2005

Several lines of evidence suggest a link between the alpha7 neuronal nicotinic acetylcholine rece... more Several lines of evidence suggest a link between the alpha7 neuronal nicotinic acetylcholine receptor (nAChR) and brain disorders including schizophrenia, Alzheimer's disease, and traumatic brain injury. The present work describes a novel molecule, 1-(5-chloro-2,4-dimethoxy-phenyl)-3-(5-methyl-isoxazol-3-yl)-urea (PNU-120596), which acts as a powerful positive allosteric modulator of the alpha7 nAChR. Discovered in a high-throughput screen, PNU-120596 increased agonist-evoked calcium flux mediated by an engineered variant of the human alpha7 nAChR. Electrophysiology studies confirmed that PNU-120596 increased peak agonist-evoked currents mediated by wild-type receptors and also demonstrated a pronounced prolongation of the evoked response in the continued presence of agonist. In contrast, PNU-120596 produced no detectable change in currents mediated by alpha4beta2, alpha3beta4, and alpha9alpha10 nAChRs. PNU-120596 increased the channel mean open time of alpha7 nAChRs but had no ...

Advances in cyclic nucleotide research, 1981

Molecular pharmacology, 1974

... Rutgers Me(lical School, Piscataway, New Jersey 08854 (Received September 11, 1973) SUMMAItY ... more ... Rutgers Me(lical School, Piscataway, New Jersey 08854 (Received September 11, 1973) SUMMAItY BROWNING, EDWARD T., GROPPI, VINCENT E., JR., AND KON, CHRISTINE: Papaver-inc. a potent inhibitor of respiration in C-fl astrocytoma cells. Mol. Pharmacol. 10, ...

The Journal of pharmacology and experimental therapeutics, 1992

Cromakalim has been shown to have anti-ischemic properties, but it also produces profound hypoten... more Cromakalim has been shown to have anti-ischemic properties, but it also produces profound hypotension upon systemic administration. We hypothesized that U-89,232, a cromakalim analog, would reduce infarct size in an ischemia-reperfusion injury model without hemodynamic alteration. Twenty-four anesthetized, open chest New Zealand White rabbits were instrumented for occlusion of a marginal branch of the left coronary artery. All animals were subjected to coronary artery occlusion (30 min) and reperfusion (2 hr). Study animals received either cromakalim (20 micrograms/kg, i.v.) or U-89,232 (20 micrograms/kg, i.v.), which was given as a pretreatment 30 min before occlusion. Control animals (n = 10) received vehicle (10% dimethyl sulfoxide). At termination of the experiment, the necrotic area and the area at risk were determined with tetrazolium and India ink staining, and infarct size was calculated using planimetry. Treatment with cromakalim produced profound hypotension (greater than ...

Protein expression and purification, 2011

Nicotinic acetylcholine receptors (nAChRs) form ligand-gated ion channels that mediate fast signa... more Nicotinic acetylcholine receptors (nAChRs) form ligand-gated ion channels that mediate fast signal transmission at synapses. These receptors are members of a large family of pentameric ion channels that are of active medical interest. An expression system utilizing a chimerical construct of the N-terminal extracellular ligand binding domain of alpha7 type nAChR and the C-terminal transmembrane portion of 5HT3 type receptor resulted high level of expressions. Two ligand affinity chromatography purification methods for this receptor have been developed. One method relies on the covalent immobilization of a high affinity small molecule alpha7 nAChR agonist, (R)-5-(4-aminophenyl)-N-(quinuclidin-3-yl) furan-2-carboxamide, and the other uses mono biotinylated alpha-bungarotoxin, an antagonist, that forms a quasi-irreversible complex with alpha7 nAChR. Detergent solubilized alpha7/5HT(3) chimeric receptors were selectively retained on the affinity resins and could be eluted with free ligan...

The Journal of cell biology, 1981

Cholera toxin catalyzes transfer of radiolabel from [32P]NAD+ to several peptides in particulate ... more Cholera toxin catalyzes transfer of radiolabel from [32P]NAD+ to several peptides in particulate preparations of human foreskin fibroblasts. Resolution of these peptides by two-dimensional gel electrophoresis allowed identification of two peptides of Mr = 42,000 and 52,000 as peptide subunits of a regulatory component of adenylate cyclase. The radiolabeling of another group of peptides (Mr = 50,000 to 65,000) suggested that cholera toxin could catalyze ADP-ribosylation of cytoskeletal proteins. This suggestion was confirmed by showing that incubation with cholera toxin and [32P]NAD+ caused radiolabeling of purified microtubule and intermediate filament proteins.

Journal of Pharmacology and Experimental Therapeutics, 2004

Human nicotinic acetylcholine receptor (nAChR) ␣7 subunits were stably and heterologously express... more Human nicotinic acetylcholine receptor (nAChR) ␣7 subunits were stably and heterologously expressed in native nAChR-null SH-EP1 human epithelial cells. Immunofluorescence staining shows ␣7 subunit protein expression in virtually every transfected cell. Microautoradiographic analysis identifies 125 Ilabeled ␣-bungarotoxin (I-Bgt) binding sites corresponding to human ␣7 (h␣7)-nAChRs on the surface of most cells. I-Bgt binds to h␣7-nAChRs in membrane fractions with a typical apparent K D value of ϳ5 nM and B max value of ϳ1 pmol/mg membrane protein, and 62% of these sites are expressed on the cell surface. Function of heterologously expressed h␣7-nAChRs is evident as rapid, transient inward current responses to (Ϫ)-nicotine. Nicotine treatment of transfected cells produces dose-and time-dependent increases (up to ϳ100%) in numbers of I-Bgt binding sites. Epibatidine is a useful ligand for

The Journal of Membrane Biology, 1994

We describe the activation of a K + current and inhibition of a C1-current by a cyanoguanidine ac... more We describe the activation of a K + current and inhibition of a C1-current by a cyanoguanidine activator of ATP-sensitive K + channels (KATP) in the smooth muscle cell line A10. The efficacy of U83757, an analogue of pinacidil, as an activator of KAT P was confirmed in single channel experiments on isolated ventricular myocytes. The effects of U83757 were examined in the clonal smooth muscle cell line A10 using voltage-sensitive dyes and digital fluorescent imaging techniques. Exposure of A10 cells to U83757 (10 nM to 1 ~tM) produced a rapid membrane hyperpolarization as monitored by the membrane potential-sensitive dye bis-oxonol ([diBAC4(3)], 5 ~tM). The U83757induced hyperpolarization was antagonized by glyburide and tetrapropylammonium (TPrA) but not by tetraethlylammonium (TEA) or charybdotoxin (ChTX). The molecular basis of the observed hyperpolarization was studied in whole-cell, voltage-clamp experiments. Exposure of voltage-clamped cells to U83757 (300 nM to 300 ~tM) produced a hyperpolarizing shift in the zero current potential; however, the hyperpolarizing shift in reversal potential was associated with either an increase or decrease in membrane conductance. In solutions where E K =-82 mV and Ecl = 0 mV, the reversal potential of the U83757-sensitive current was approximately-70 mV in those experiments where an increase in membrane conductance was observed. In experiments in which a decrease in conductance was observed, the reversal potential of the U83757-sensitive current was approximately 0 mV, suggesting that U83757 might be acting as a C1-channel blocker as well as a K +chan-Correspondence to: DJ. Nelson nel opener. In experiments in which C1-current activation was specifically brought about by cellular swelling and performed in solutions where C1-was the major permeant ion, U83757 (300 nM tO 300 gM) produced a dose-dependent current inhibition. Taken together these results (i) demonstrate the presence of a K+-selective current which is sensitive to KAy P channel openers in A10 cells and (ii) indicate that the hyperpolarizing effects of K + channel openers in vascular smooth muscle may be due to both the inhibition of C1currents as well as the activation of a K+-selective current.