Search

Your search keyword '"Martínez, Allyson K."' showing total 12 results
Start Over Author "Martínez, Allyson K."
12 results on '"Martínez, Allyson K."'

8. Nicotine Promotes Cholangiocarcinoma Growth in Xenograft Mice

Author

Martínez, Allyson K., primary, Jensen, Kendal, additional, Hall, Chad, additional, O'Brien, April, additional, Ehrlich, Laurent, additional, White, Tori, additional, Meng, Fanyin, additional, Zhou, Tianhao, additional, Greene, John, additional, Bernuzzi, Francesca, additional, Invernizzi, Pietro, additional, Dostal, David E., additional, Lairmore, Terry, additional, Alpini, Gianfranco, additional, and Glaser, Shannon S., additional

Published
2017
Full Text
View/download PDF

9. Activation of the renin-angiotensin system stimulates biliary hyperplasia during cholestasis induced by extrahepatic bile duct ligation

Author

Afroze, Syeda H., primary, Munshi, Md Kamruzzaman, additional, Martínez, Allyson K., additional, Uddin, Mohammad, additional, Gergely, Maté, additional, Szynkarski, Claudia, additional, Guerrier, Micheleine, additional, Nizamutdinov, Damir, additional, Dostal, David, additional, and Glaser, Shannon, additional

Published
2015
Full Text
View/download PDF

11. Structural basis for the tryptophan sensitivity of TnaC-mediated ribosome stalling

Author

van der Stel, Anne-Xander, Gordon, Emily R., Sengupta, Arnab, Martínez, Allyson K., Klepacki, Dorota, Perry, Thomas N., Herrero del Valle, Alba, Vázquez-Laslop, Nora, Sachs, Matthew S., Cruz-Vera, Luis R., and Innis, C. Axel

Subjects
Models, Molecular, Protein Conformation, alpha-Helical, Binding Sites, Escherichia coli Proteins, Science, Cryoelectron Microscopy, Tryptophan, Gene Expression Regulation, Bacterial, Peptide Chain Termination, Translational, RNA, Transfer, Amino Acyl, Ribosome, Article, Amino Acid Substitution, Mutation, Operon, Escherichia coli, Protein Conformation, beta-Strand, Protein Interaction Domains and Motifs, Peptide Chain Initiation, Translational, Ribosomes, Peptide Termination Factors, Protein Binding
Abstract

Free L-tryptophan (L-Trp) stalls ribosomes engaged in the synthesis of TnaC, a leader peptide controlling the expression of the Escherichia coli tryptophanase operon. Despite extensive characterization, the molecular mechanism underlying the recognition and response to L-Trp by the TnaC-ribosome complex remains unknown. Here, we use a combined biochemical and structural approach to characterize a TnaC variant (R23F) with greatly enhanced sensitivity for L-Trp. We show that the TnaC–ribosome complex captures a single L-Trp molecule to undergo termination arrest and that nascent TnaC prevents the catalytic GGQ loop of release factor 2 from adopting an active conformation at the peptidyl transferase center. Importantly, the L-Trp binding site is not altered by the R23F mutation, suggesting that the relative rates of L-Trp binding and peptidyl-tRNA cleavage determine the tryptophan sensitivity of each variant. Thus, our study reveals a strategy whereby a nascent peptide assists the ribosome in detecting a small metabolite., Bacteria adjust the expression of some of their metabolic enzymes through metabolite-sensing ribosome nascent chain complexes. Here the authors present a cryo-EM structure of an E. coli ribosome stalled during translation of the TnaC leader peptide and propose a model for L-Trp dependent ribosome stalling where L-Trp competes with release factor 2 for binding to the TnaC-ribosome complex.

Full Text
View/download PDF

12. Activation of the renin-angiotensin system stimulates biliary hyperplasia during cholestasis induced by extrahepatic bile duct ligation.

Author

Afroze SH, Munshi MK, Martínez AK, Uddin M, Gergely M, Szynkarski C, Guerrier M, Nizamutdinov D, Dostal D, and Glaser S

Subjects
Angiotensin II Type 1 Receptor Blockers pharmacology, Animals, Bile Ducts, Extrahepatic pathology, Cell Line, Cholestasis, Extrahepatic genetics, Cholestasis, Extrahepatic pathology, Cholestasis, Extrahepatic prevention & control, Disease Models, Animal, Fibrosis, Gene Expression Regulation, Hyperplasia, Ligation, Losartan pharmacology, Male, Rats, Inbred F344, Renin-Angiotensin System genetics, Signal Transduction drug effects, Angiotensin II pharmacology, Bile Ducts, Extrahepatic drug effects, Bile Ducts, Extrahepatic surgery, Cell Proliferation drug effects, Cholestasis, Extrahepatic etiology, Cholestasis, Extrahepatic metabolism, Renin-Angiotensin System drug effects
Abstract

Cholangiocyte proliferation is regulated in a coordinated fashion by many neuroendocrine factors through autocrine and paracrine mechanisms. The renin-angiotensin system (RAS) is known to play a role in the activation of hepatic stellate cells and blocking the RAS attenuates hepatic fibrosis. We investigated the role of the RAS during extrahepatic cholestasis induced by bile duct ligation (BDL). In this study, we used normal and BDL rats that were treated with control, angiotensin II (ANG II), or losartan for 2 wk. In vitro studies were performed in a primary rat cholangiocyte cell line (NRIC). The expression of renin, angiotensin-converting enzyme, angiotensinogen, and angiotensin receptor type 1 was evaluated by immunohistochemistry (IHC), real-time PCR, and FACs and found to be increased in BDL compared with normal rat. The levels of ANG II were evaluated by ELISA and found to be increased in serum and conditioned media of cholangiocytes from BDL compared with normal rats. Treatment with ANG II increased biliary mass and proliferation in both normal and BDL rats. Losartan attenuated BDL-induced biliary proliferation. In vitro, ANG II stimulated NRIC proliferation via increased intracellular cAMP levels and activation of the PKA/ERK/CREB intracellular signaling pathway. ANG II stimulated a significant increase in Sirius red staining and IHC for fibronectin that was blocked by angiotensin receptor blockade. In vitro, ANG II stimulated the gene expression of collagen 1A1, fibronectin 1, and IL-6. These results indicate that cholangiocytes express a local RAS and that ANG II plays an important role in regulating biliary proliferation and fibrosis during extraheptic cholestasis., (Copyright © 2015 the American Physiological Society.)

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results