1
|
Wang W, Ranjan A, Zhang W, Liang Q, MacMillan KS, Chapman K, Wang X, Chandrasekaran P, Williams NS, Rosenbaum DM, De Brabander JK. Novel orexin receptor agonists based on arene- or pyridine-fused 1,3-dihydro-2H-imidazole-2-imines. Bioorg Med Chem Lett 2024; 99:129624. [PMID: 38272190 DOI: 10.1016/j.bmcl.2024.129624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/15/2023] [Accepted: 01/18/2024] [Indexed: 01/27/2024]
Abstract
A structurally novel class of benzo- or pyrido-fused 1,3-dihydro-2H-imidazole-2-imines was designed and evaluated in an inositol phosphate accumulation assay for Gq signaling to measure agonistic activation of the orexin receptor type 2 (OX2R). These compounds were synthesized in 4-9 steps overall from readily available starting materials. Analogs that contain a stereogenic methyl or cyclopropyl substituent at the benzylic center, and a correctly configured alkyl ether, alkoxyalkyl ether, cyanoalkyl ether, or α-hydroxyacetamido substituted homobenzylic sidechain were identified as the most potent activators of OX2R coupled Gq signaling. Our results also indicate that agonistic activity was stereospecific at both the benzylic and homobenzylic stereogenic centra. We identified methoxyethoxy-substituted pyrido-fused dihydroimidazolimine analog 63c containing a stereogenic benzylic methyl group was the most potent agonist, registering a respectable EC50 of 339 nM and a maximal response (Emax) of 96 % in this assay. In vivo pharmacokinetic analysis indicated good brain exposure for several analogs. Our combined results provide important information towards a structurally novel class of orexin receptor agonists distinct from current chemotypes.
Collapse
Affiliation(s)
- Wentian Wang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Alok Ranjan
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Wei Zhang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Qiren Liang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Karen S MacMillan
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Karen Chapman
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA
| | - Xiaoyu Wang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Preethi Chandrasekaran
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA
| | - Noelle S Williams
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA.
| | - Jef K De Brabander
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA.
| |
Collapse
|
2
|
Kober DL, Caballero Van Dyke MC, Eitson JL, Boys IN, McDougal MB, Rosenbaum DM, Schoggins JW. Development of a mutant aerosolized ACE2 that neutralizes SARS-CoV-2 in vivo. bioRxiv 2023:2023.09.26.559550. [PMID: 37808801 PMCID: PMC10557691 DOI: 10.1101/2023.09.26.559550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The rapid evolution of SARS-CoV-2 variants highlights the need for new therapies to prevent disease spread. SARS-CoV-2, like SARS-CoV-1, uses the human cell surface protein angiotensin-converting enzyme 2 (ACE2) as its native receptor. Here, we design and characterize a mutant ACE2 that enables rapid affinity purification of a dimeric protein by altering the active site to prevent autoproteolytic digestion of a C-terminal His10 epitope tag. In cultured cells, mutant ACE2 competitively inhibits lentiviral vectors pseudotyped with spike from multiple SARS-CoV-2 variants, and infectious SARS-CoV-2. Moreover, the protein can be nebulized and retains virus-binding properties. We developed a system for delivery of aerosolized ACE2 to K18-hACE2 mice and demonstrate protection by our modified ACE2 when delivered as a prophylactic agent. These results show proof-of-concept for an aerosolized delivery method to evaluate anti-SARS-CoV-2 agents in vivo and suggest a new tool in the ongoing fight against SARS-CoV-2 and other ACE2-dependent viruses.
Collapse
Affiliation(s)
- Daniel L. Kober
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Jennifer L. Eitson
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ian N. Boys
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Matthew B. McDougal
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Daniel M. Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - John W. Schoggins
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| |
Collapse
|
3
|
Yin J, Kang Y, McGrath AP, Chapman K, Sjodt M, Kimura E, Okabe A, Koike T, Miyanohana Y, Shimizu Y, Rallabandi R, Lian P, Bai X, Flinspach M, De Brabander JK, Rosenbaum DM. Reply to: The G protein preference of orexin receptors is currently an unresolved issue. Nat Commun 2023; 14:3163. [PMID: 37264001 DOI: 10.1038/s41467-023-38765-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 05/15/2023] [Indexed: 06/03/2023] Open
Affiliation(s)
- Jie Yin
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA
- Chinese Institute for Brain Research, No. 26 Science Park Road, Zhongguancun Life Science Park, Changping District, Beijing, China
| | - Yanyong Kang
- Takeda Development Center Americas, Inc., 9625 Towne Centre Drive, San Diego, CA, 92121, USA
| | - Aaron P McGrath
- Takeda Development Center Americas, Inc., 9625 Towne Centre Drive, San Diego, CA, 92121, USA
| | - Karen Chapman
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA
| | - Megan Sjodt
- Takeda Development Center Americas, Inc., 9625 Towne Centre Drive, San Diego, CA, 92121, USA
| | - Eiji Kimura
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Atsutoshi Okabe
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Tatsuki Koike
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Yuhei Miyanohana
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Yuji Shimizu
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Rameshu Rallabandi
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Peng Lian
- BioHPC at the Lyda Hill Department of Bioinformatics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Xiaochen Bai
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA
| | - Mack Flinspach
- Takeda Development Center Americas, Inc., 9625 Towne Centre Drive, San Diego, CA, 92121, USA.
| | - Jef K De Brabander
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA.
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
4
|
Kumari P, Inoue A, Chapman K, Lian P, Rosenbaum DM. Molecular mechanism of fatty acid activation of FFAR1. Proc Natl Acad Sci U S A 2023; 120:e2219569120. [PMID: 37216523 PMCID: PMC10235965 DOI: 10.1073/pnas.2219569120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 04/03/2023] [Indexed: 05/24/2023] Open
Abstract
FFAR1 is a G-protein-coupled receptor (GPCR) that responds to circulating free fatty acids to enhance glucose-stimulated insulin secretion and release of incretin hormones. Due to the glucose-lowering effect of FFAR1 activation, potent agonists for this receptor have been developed for the treatment of diabetes. Previous structural and biochemical studies of FFAR1 showed multiple sites of ligand binding to the inactive state but left the mechanism of fatty acid interaction and receptor activation unknown. We used cryo-electron microscopy to elucidate structures of activated FFAR1 bound to a Gq mimetic, which were induced either by the endogenous FFA ligand docosahexaenoic acid or γ-linolenic acid and the agonist drug TAK-875. Our data identify the orthosteric pocket for fatty acids and show how both endogenous hormones and synthetic agonists induce changes in helical packing along the outside of the receptor that propagate to exposure of the G-protein-coupling site. These structures show how FFAR1 functions without the highly conserved "DRY" and "NPXXY" motifs of class A GPCRs and also illustrate how the orthosteric site of a receptor can be bypassed by membrane-embedded drugs to confer full activation of G protein signaling.
Collapse
Affiliation(s)
- Punita Kumari
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Asuka Inoue
- Department of Pharmaceutical Sciences, Tohoku University, Sendai980-8578, Japan
| | - Karen Chapman
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Peng Lian
- BioHPC at the Lyda Hill Department of Bioinformatics, The University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Daniel M. Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX75390
| |
Collapse
|
5
|
Sun Y, Ranjan A, Tisdale R, Ma SC, Park S, Haire M, Heu J, Morairty SR, Wang X, Rosenbaum DM, Williams NS, De Brabander JK, Kilduff TS. Evaluation of the efficacy of the hypocretin/orexin receptor agonists TAK-925 and ARN-776 in narcoleptic orexin/tTA; TetO-DTA mice. J Sleep Res 2023:e13839. [PMID: 36808670 DOI: 10.1111/jsr.13839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/29/2022] [Accepted: 01/16/2023] [Indexed: 02/22/2023]
Abstract
The sleep disorder narcolepsy, a hypocretin deficiency disorder thought to be due to degeneration of hypothalamic hypocretin/orexin neurons, is currently treated symptomatically. We evaluated the efficacy of two small molecule hypocretin/orexin receptor-2 (HCRTR2) agonists in narcoleptic male orexin/tTA; TetO-DTA mice. TAK-925 (1-10 mg/kg, s.c.) and ARN-776 (1-10 mg/kg, i.p.) were injected 15 min before dark onset in a repeated measures design. EEG, EMG, subcutaneous temperature (Tsc ) and activity were recorded by telemetry; recordings for the first 6 h of the dark period were scored for sleep/wake and cataplexy. At all doses tested, TAK-925 and ARN-776 caused continuous wakefulness and eliminated sleep for the first hour. Both TAK-925 and ARN-776 caused dose-related delays in NREM sleep onset. All doses of TAK-925 and all but the lowest dose of ARN-776 eliminated cataplexy during the first hour after treatment; the anti-cataplectic effect of TAK-925 persisted into the second hour for the highest dose. TAK-925 and ARN-776 also reduced the cumulative amount of cataplexy during the 6 h post-dosing period. The acute increase in wakefulness produced by both HCRTR2 agonists was characterised by increased spectral power in the gamma EEG band. Although neither compound provoked a NREM sleep rebound, both compounds affected NREM EEG during the second hour post-dosing. TAK-925 and ARN-776 also increased gross motor activity, running wheel activity, and Tsc , suggesting that the wake-promoting and sleep-suppressing activities of these compounds could be a consequence of hyperactivity. Nonetheless, the anti-cataplectic activity of TAK-925 and ARN-776 is encouraging for the development of HCRTR2 agonists.
Collapse
Affiliation(s)
- Yu Sun
- Biosciences Division, SRI International, Menlo Park, California, USA
| | - Alok Ranjan
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ryan Tisdale
- Biosciences Division, SRI International, Menlo Park, California, USA
| | - Shun-Chieh Ma
- Biosciences Division, SRI International, Menlo Park, California, USA
| | - Sunmee Park
- Biosciences Division, SRI International, Menlo Park, California, USA
| | - Meghan Haire
- Biosciences Division, SRI International, Menlo Park, California, USA
| | - Jasmine Heu
- Biosciences Division, SRI International, Menlo Park, California, USA
| | | | - Xiaoyu Wang
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Daniel M Rosenbaum
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Noelle S Williams
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jef K De Brabander
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Thomas S Kilduff
- Biosciences Division, SRI International, Menlo Park, California, USA
| |
Collapse
|
6
|
Yin J, Kang Y, McGrath AP, Chapman K, Sjodt M, Kimura E, Okabe A, Koike T, Miyanohana Y, Shimizu Y, Rallabandi R, Lian P, Bai X, Flinspach M, De Brabander JK, Rosenbaum DM. Molecular mechanism of the wake-promoting agent TAK-925. Nat Commun 2022; 13:2902. [PMID: 35614071 PMCID: PMC9133036 DOI: 10.1038/s41467-022-30601-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/05/2022] [Indexed: 11/30/2022] Open
Abstract
The OX2 orexin receptor (OX2R) is a highly expressed G protein-coupled receptor (GPCR) in the brain that regulates wakefulness and circadian rhythms in humans. Antagonism of OX2R is a proven therapeutic strategy for insomnia drugs, and agonism of OX2R is a potentially powerful approach for narcolepsy type 1, which is characterized by the death of orexinergic neurons. Until recently, agonism of OX2R had been considered 'undruggable.' We harness cryo-electron microscopy of OX2R-G protein complexes to determine how the first clinically tested OX2R agonist TAK-925 can activate OX2R in a highly selective manner. Two structures of TAK-925-bound OX2R with either a Gq mimetic or Gi reveal that TAK-925 binds at the same site occupied by antagonists, yet interacts with the transmembrane helices to trigger activating microswitches. Our structural and mutagenesis data show that TAK-925's selectivity is mediated by subtle differences between OX1 and OX2 receptor subtypes at the orthosteric pocket. Finally, differences in the polarity of interactions at the G protein binding interfaces help to rationalize OX2R's coupling selectivity for Gq signaling. The mechanisms of TAK-925's binding, activation, and selectivity presented herein will aid in understanding the efficacy of small molecule OX2R agonists for narcolepsy and other circadian disorders.
Collapse
Affiliation(s)
- Jie Yin
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA
- Chinese Institute for Brain Research, No. 26 Science Park Road, Zhongguancun Life Science Park, Changping District, Beijing, China
| | - Yanyong Kang
- Takeda Development Center Americas, Inc, 9625 Towne Centre Drive, San Diego, CA, 92121, USA
| | - Aaron P McGrath
- Takeda Development Center Americas, Inc, 9625 Towne Centre Drive, San Diego, CA, 92121, USA
| | - Karen Chapman
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA
| | - Megan Sjodt
- Takeda Development Center Americas, Inc, 9625 Towne Centre Drive, San Diego, CA, 92121, USA
| | - Eiji Kimura
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Atsutoshi Okabe
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Tatsuki Koike
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Yuhei Miyanohana
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Yuji Shimizu
- Takeda Pharmaceutical Company Ltd., 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Rameshu Rallabandi
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Peng Lian
- BioHPC at the Lyda Hill Department of Bioinformatics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Xiaochen Bai
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA
| | - Mack Flinspach
- Takeda Development Center Americas, Inc, 9625 Towne Centre Drive, San Diego, CA, 92121, USA.
| | - Jef K De Brabander
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX, 75390, USA.
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
7
|
Ramesh K, Rosenbaum DM. Molecular basis for ligand modulation of the cannabinoid CB 1 receptor. Br J Pharmacol 2021; 179:3487-3495. [PMID: 34265078 DOI: 10.1111/bph.15627] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/02/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
The cannabinoid CB1 receptor is the most abundant G protein coupled receptor (GPCR) in the central nervous system, which mediates the functional response to endocannabinoids and Cannabis compounds. A variety of ligands for CB1 receptors have been developed as promising drug candidates for the treatment of neurological disorders. New high-resolution structures of CB1 receptor in different functional states have significantly improved our molecular understanding of CB1 ligand interactions, selectivity, receptor activation and allosteric modulation. These advances have paved the way for development of novel ligands for different therapeutic applications. In this review, we describe the structural determinants for modulation of CB1 receptors by different types of ligands, as well as the differences between CB1 and its homologous, the CB2 receptor.
Collapse
Affiliation(s)
- Karthik Ramesh
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| |
Collapse
|
8
|
Kober DL, Radhakrishnan A, Goldstein JL, Brown MS, Clark LD, Bai XC, Rosenbaum DM. Scap structures highlight key role for rotation of intertwined luminal loops in cholesterol sensing. Cell 2021; 184:3689-3701.e22. [PMID: 34139175 PMCID: PMC8277531 DOI: 10.1016/j.cell.2021.05.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/08/2021] [Accepted: 05/14/2021] [Indexed: 11/26/2022]
Abstract
The cholesterol-sensing protein Scap induces cholesterol synthesis by transporting membrane-bound transcription factors called sterol regulatory element-binding proteins (SREBPs) from the endoplasmic reticulum (ER) to the Golgi apparatus for proteolytic activation. Transport requires interaction between Scap's two ER luminal loops (L1 and L7), which flank an intramembrane sterol-sensing domain (SSD). Cholesterol inhibits Scap transport by binding to L1, which triggers Scap's binding to Insig, an ER retention protein. Here we used cryoelectron microscopy (cryo-EM) to elucidate two structures of full-length chicken Scap: (1) a wild-type free of Insigs and (2) mutant Scap bound to chicken Insig without cholesterol. Strikingly, L1 and L7 intertwine tightly to form a globular domain that acts as a luminal platform connecting the SSD to the rest of Scap. In the presence of Insig, this platform undergoes a large rotation accompanied by rearrangement of Scap's transmembrane helices. We postulate that this conformational change halts Scap transport of SREBPs and inhibits cholesterol synthesis.
Collapse
Affiliation(s)
- Daniel L Kober
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Molecular Genetics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Arun Radhakrishnan
- Department of Molecular Genetics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Joseph L Goldstein
- Department of Molecular Genetics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Michael S Brown
- Department of Molecular Genetics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lindsay D Clark
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xiao-Chen Bai
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| |
Collapse
|
9
|
Xiao P, Yan W, Gou L, Zhong YN, Kong L, Wu C, Wen X, Yuan Y, Cao S, Qu C, Yang X, Yang CC, Xia A, Hu Z, Zhang Q, He YH, Zhang DL, Zhang C, Hou GH, Liu H, Zhu L, Fu P, Yang S, Rosenbaum DM, Sun JP, Du Y, Zhang L, Yu X, Shao Z. Ligand recognition and allosteric regulation of DRD1-Gs signaling complexes. Cell 2021; 184:943-956.e18. [PMID: 33571432 PMCID: PMC11005940 DOI: 10.1016/j.cell.2021.01.028] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 12/01/2020] [Accepted: 01/15/2021] [Indexed: 02/08/2023]
Abstract
Dopamine receptors, including D1- and D2-like receptors, are important therapeutic targets in a variety of neurological syndromes, as well as cardiovascular and kidney diseases. Here, we present five cryoelectron microscopy (cryo-EM) structures of the dopamine D1 receptor (DRD1) coupled to Gs heterotrimer in complex with three catechol-based agonists, a non-catechol agonist, and a positive allosteric modulator for endogenous dopamine. These structures revealed that a polar interaction network is essential for catecholamine-like agonist recognition, whereas specific motifs in the extended binding pocket were responsible for discriminating D1- from D2-like receptors. Moreover, allosteric binding at a distinct inner surface pocket improved the activity of DRD1 by stabilizing endogenous dopamine interaction at the orthosteric site. DRD1-Gs interface revealed key features that serve as determinants for G protein coupling. Together, our study provides a structural understanding of the ligand recognition, allosteric regulation, and G protein coupling mechanisms of DRD1.
Collapse
Affiliation(s)
- Peng Xiao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China; Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Wei Yan
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Lu Gou
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Ya-Ni Zhong
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Liangliang Kong
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Chao Wu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xin Wen
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Yuan Yuan
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Sheng Cao
- School of Life and Health Sciences, Kobilka Institute of Innovative Drug Discovery, Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Changxiu Qu
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Xin Yang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Chuan-Cheng Yang
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Anjie Xia
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Zhenquan Hu
- Warshel Institute for Computational Biology, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Qianqian Zhang
- School of Pharmacy, Lanzhou University, Lanzhou 730000, China
| | - Yong-Hao He
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China; School of Pharmacy, Binzhou Medical University, Yantai, Shandong 264003, China
| | - Dao-Lai Zhang
- School of Pharmacy, Binzhou Medical University, Yantai, Shandong 264003, China
| | - Chao Zhang
- Biomedical Isotope Research Center, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Gui-Hua Hou
- Biomedical Isotope Research Center, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Huanxiang Liu
- School of Pharmacy, Lanzhou University, Lanzhou 730000, China
| | - Lizhe Zhu
- Warshel Institute for Computational Biology, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Ping Fu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Shengyong Yang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jin-Peng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China; Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing 100191, China.
| | - Yang Du
- School of Life and Health Sciences, Kobilka Institute of Innovative Drug Discovery, Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China.
| | - Lei Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xiao Yu
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China.
| | - Zhenhua Shao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
| |
Collapse
|
10
|
Abstract
The orexin receptors are peptide-sensing G protein-coupled receptors that are intimately linked with regulation of the sleep/wake cycle. We used a recently solved X-ray structure of the orexin receptor subtype 2 in computational docking calculations with the aim to identify additional ligands with unprecedented chemotypes. We found validated ligands with a high hit rate of 29% out of those tested, none of them showing selectivity with respect to the orexin receptor subtype 1. Furthermore, of the higher-affinity compounds examined, none showed any agonist activity. While novel chemical structures can thus be found, selectivity is a challenge owing to the largely identical binding pockets.
Collapse
Affiliation(s)
- Jakub Gunera
- Department of Pharmaceutical Chemistry, Philipps-University, Marburg, Hesse 35032, Germany
| | - Jillian G Baker
- Cell Signalling, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
| | - Niek van Hilten
- Department of Pharmaceutical Chemistry, Philipps-University, Marburg, Hesse 35032, Germany
| | - Daniel M Rosenbaum
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, Texas 75390-8816, United States
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps-University, Marburg, Hesse 35032, Germany
| |
Collapse
|
11
|
Yin J, Chen KYM, Clark MJ, Hijazi M, Kumari P, Bai XC, Sunahara RK, Barth P, Rosenbaum DM. Structure of a D2 dopamine receptor-G-protein complex in a lipid membrane. Nature 2020; 584:125-129. [PMID: 32528175 PMCID: PMC7415663 DOI: 10.1038/s41586-020-2379-5] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/08/2020] [Indexed: 12/28/2022]
Abstract
The D2 dopamine receptor (DRD2) is a therapeutic target for Parkinson’s disease1 and antipsychotic drugs2. DRD2 is activated by the endogenous neurotransmitter dopamine and synthetic agonist drugs such as bromocriptine3, leading to stimulation of Gi and inhibition of adenylyl cyclase. We used cryo-electron microscopy to elucidate the structure of an agonist-bound activated DRD2-Gi complex reconstituted into a phospholipid membrane. The extracellular ligand binding site of DRD2 is remodeled in response to agonist binding, with conformational changes in extracellular loop 2 (ECL2), transmembrane domain 5 (TM5), TM6, and TM7 propagating to opening of the intracellular Gi binding site. The DRD2-Gi structure represents the first experimental model of a GPCR-G protein complex embedded in a phospholipid bilayer, which serves as a benchmark to validate the interactions seen in previous detergent-bound structures. The structure also reveals interactions that are unique to the membrane-embedded complex, including helix 8 burial in the inner leaflet, ordered lysine and arginine sidechains in the membrane interfacial regions, and lipid anchoring of the G protein in the membrane. Our model of the activated DRD2 will help inform the design of subtype-selective DRD2 ligands for multiple human CNS disorders.
Collapse
Affiliation(s)
- Jie Yin
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kuang-Yui M Chen
- Institute of Bioengineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Mary J Clark
- Department of Pharmacology, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Mahdi Hijazi
- Institute of Bioengineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Punita Kumari
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiao-Chen Bai
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Roger K Sunahara
- Department of Pharmacology, University of California San Diego School of Medicine, La Jolla, CA, USA.
| | - Patrick Barth
- Institute of Bioengineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, USA.
| |
Collapse
|
12
|
Ali R, Clark LD, Zahm JA, Lemoff A, Ramesh K, Rosenbaum DM, Rosen MK. Improved strategy for isoleucine 1H/ 13C methyl labeling in Pichia pastoris. J Biomol NMR 2019; 73:687-697. [PMID: 31541396 PMCID: PMC6875547 DOI: 10.1007/s10858-019-00281-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 09/12/2019] [Indexed: 06/10/2023]
Abstract
Site specific methyl labeling combined with methyl TROSY offers a powerful NMR approach to study structure and dynamics of proteins and protein complexes of high molecular weight. Robust and cost-effective methods have been developed for site specific protein 1H/13C methyl labeling in an otherwise deuterated background in bacteria. However, bacterial systems are not suitable for expression and isotope labeling of many eukaryotic and membrane proteins. The yeast Pichia pastoris (P. pastoris) is a commonly used host for expression of eukaryotic proteins, and site-specific methyl labeling of perdeuterated eukaryotic proteins has recently been achieved with this system. However, the practical utility of methyl labeling and deuteration in P. pastoris is limited by high costs. Here, we describe an improved method for 1H/13C-labeling of the δ-methyl group of isoleucine residues in a perdeuterated background, which reduces the cost by ≥ 50% without compromising the efficiency of isotope enrichment. We have successfully implemented this method to label actin and a G-protein coupled receptor. Our approach will facilitate studies of the structure and dynamics of eukaryotic proteins by NMR spectroscopy.
Collapse
Affiliation(s)
- Rustam Ali
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Lindsay D Clark
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Jacob A Zahm
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 130 Longwood Avenue, Boston, MA, 02115, USA
| | - Andrew Lemoff
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Karthik Ramesh
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Michael K Rosen
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
13
|
Uchański T, Zögg T, Yin J, Yuan D, Wohlkönig A, Fischer B, Rosenbaum DM, Kobilka BK, Pardon E, Steyaert J. An improved yeast surface display platform for the screening of nanobody immune libraries. Sci Rep 2019; 9:382. [PMID: 30674983 PMCID: PMC6344588 DOI: 10.1038/s41598-018-37212-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/30/2018] [Indexed: 11/08/2022] Open
Abstract
Fusions to the C-terminal end of the Aga2p mating adhesion of Saccharomyces cerevisiae have been used in many studies for the selection of affinity reagents by yeast display followed by flow cytometric analysis. Here we present an improved yeast display system for the screening of Nanobody immune libraries where we fused the Nanobody to the N-terminal end of Aga2p to avoid steric hindrance between the fused Nanobody and the antigen. Moreover, the display level of a cloned Nanobody on the surface of an individual yeast cell can be monitored through a covalent fluorophore that is attached in a single enzymatic step to an orthogonal acyl carrier protein (ACP). Additionally, the displayed Nanobody can be easily released from the yeast surface and immobilised on solid surfaces for rapid analysis. To prove the generic nature of this novel Nanobody discovery platform, we conveniently selected Nanobodies against three different antigens, including two membrane proteins.
Collapse
Affiliation(s)
- Tomasz Uchański
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Thomas Zögg
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Jie Yin
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Daopeng Yuan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Alexandre Wohlkönig
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Baptiste Fischer
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Brian K Kobilka
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, 94305, USA
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium.
| |
Collapse
|
14
|
Clark L, Dikiy I, Rosenbaum DM, Gardner KH. On the use of Pichia pastoris for isotopic labeling of human GPCRs for NMR studies. J Biomol NMR 2018; 71:203-211. [PMID: 30121871 PMCID: PMC7282444 DOI: 10.1007/s10858-018-0204-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/09/2018] [Indexed: 05/21/2023]
Abstract
NMR studies of human integral membrane proteins provide unique opportunities to probe structure and dynamics at specific locations and on multiple timescales, often with significant implications for disease mechanism and drug development. Since membrane proteins such as G protein-coupled receptors (GPCRs) are highly dynamic and regulated by ligands or other perturbations, NMR methods are potentially well suited to answer basic functional questions (such as addressing the biophysical basis of ligand efficacy) as well as guiding applications (such as novel ligand design). However, such studies on eukaryotic membrane proteins have often been limited by the inability to incorporate optimal isotopic labels for NMR methods developed for large protein/lipid complexes, including methyl TROSY. We review the different expression systems for production of isotopically labeled membrane proteins and highlight the use of the yeast Pichia pastoris to achieve perdeuteration and 13C methyl probe incorporation within isoleucine sidechains. We further illustrate the use of this method for labeling of several biomedically significant GPCRs.
Collapse
Affiliation(s)
- Lindsay Clark
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-8816, USA
- Molecular Biophysics Graduate Program, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Igor Dikiy
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, NY, 10031, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-8816, USA.
- Molecular Biophysics Graduate Program, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Kevin H Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, NY, 10031, USA.
- Department of Chemistry and Biochemistry, City College of New York, New York, NY, 10031, USA.
- Biochemistry, Chemistry and Biology Ph.D. Programs, Graduate Center, City University of New York, New York, NY, 10016, USA.
| |
Collapse
|
15
|
Clark LD, Dikiy I, Chapman K, Rodstrom KE, Aramini J, LeVine MV, Khelashvili G, Rasmussen SG, Gardner KH, Rosenbaum DM. Ligand Modulation of Sidechain Dynamics in a Wild-Type Human GPCR. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
|
16
|
Clark LD, Dikiy I, Chapman K, Rödström KE, Aramini J, LeVine MV, Khelashvili G, Rasmussen SG, Gardner KH, Rosenbaum DM. Ligand modulation of sidechain dynamics in a wild-type human GPCR. eLife 2017; 6:28505. [PMID: 28984574 PMCID: PMC5650471 DOI: 10.7554/elife.28505] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 09/20/2017] [Indexed: 11/13/2022] Open
Abstract
GPCRs regulate all aspects of human physiology, and biophysical studies have deepened our understanding of GPCR conformational regulation by different ligands. Yet there is no experimental evidence for how sidechain dynamics control allosteric transitions between GPCR conformations. To address this deficit, we generated samples of a wild-type GPCR (A2AR) that are deuterated apart from 1H/13C NMR probes at isoleucine δ1 methyl groups, which facilitated 1H/13C methyl TROSY NMR measurements with opposing ligands. Our data indicate that low [Na+] is required to allow large agonist-induced structural changes in A2AR, and that patterns of sidechain dynamics substantially differ between agonist (NECA) and inverse agonist (ZM241385) bound receptors, with the inverse agonist suppressing fast ps-ns timescale motions at the G protein binding site. Our approach to GPCR NMR creates a framework for exploring how different regions of a receptor respond to different ligands or signaling proteins through modulation of fast ps-ns sidechain dynamics.
Collapse
Affiliation(s)
- Lindsay D Clark
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, United States.,Molecular Biophysics Graduate Program, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Igor Dikiy
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, United States
| | - Karen Chapman
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Karin Ej Rödström
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - James Aramini
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, United States
| | - Michael V LeVine
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, United States.,Institute for Computational Bioscience, Weill Cornell Medical College, New York, United States
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, United States.,Institute for Computational Bioscience, Weill Cornell Medical College, New York, United States
| | - Søren Gf Rasmussen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kevin H Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, United States.,Department of Chemistry and Biochemistry, City College of New York, New York, United States.,Biochemistry, Chemistry and Biology PhD Programs, Graduate Center, City University of New York, New York, United States
| | - Daniel M Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, United States.,Molecular Biophysics Graduate Program, The University of Texas Southwestern Medical Center, Dallas, United States
| |
Collapse
|
17
|
Zhou J, Li J, Rosenbaum DM, Zhuang J, Poon C, Qin P, Rivera K, Lepore J, Willette RN, Hu E, Barone FC. The prolyl 4-hydroxylase inhibitor GSK360A decreases post-stroke brain injury and sensory, motor, and cognitive behavioral deficits. PLoS One 2017; 12:e0184049. [PMID: 28880966 PMCID: PMC5589177 DOI: 10.1371/journal.pone.0184049] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/17/2017] [Indexed: 12/20/2022] Open
Abstract
There is interest in pharmacologic preconditioning for end-organ protection by targeting the HIF system. This can be accomplished by inhibition of prolyl 4-hydroxylase (PHD). GSK360A is an orally active PHD inhibitor that has been previously shown to protect the failing heart. We hypothesized that PHD inhibition can also protect the brain from injuries and resulting behavioral deficits that can occur as a result of surgery. Thus, our goal was to investigate the effect of pre-stroke surgery brain protection using a verified GSK360A PHD inhibition paradigm on post-stroke surgery outcomes. Vehicle or an established protective dose (30 mg/kg, p.o.) of GSK360A was administered to male Sprague-Dawley rats. Initially, GSK360A pharmacokinetics and organ distribution were determined, and then PHD-HIF pharmacodynamic markers were measured (i.e., to validate the pharmacological effects of the GSK360A administration regimen). Results obtained using this validated PHD dose-regimen indicated significant improvement by GSK360A (30mg/kg); administered at 18 and 5 hours prior to transient middle cerebral artery occlusion (stroke). GSK360A exposure and plasma, kidney and brain HIF-PHD pharmacodynamics endpoints (e.g., erythropoietin; EPO and Vascular Endothelial Growth Factor; VEGF) were measured. GSK360A provided rapid exposure in plasma (7734 ng/ml), kidney (45–52% of plasma level) and brain (1–4% of plasma level), and increased kidney EPO mRNA (80-fold) and brain VEGF mRNA (2-fold). We also observed that GSK360A increased plasma EPO (300-fold) and VEGF (2-fold). Further assessments indicated that GSK360A reduced post-stroke surgery neurological deficits (47–64%), cognitive dysfunction (60–75%) and brain infarction (30%) 4 weeks later. Thus, PHD inhibition using GSK360A pretreatment produced long-term post-stroke brain protection and improved behavioral functioning. These data support PHD inhibition, specifically by GSK360A, as a potential strategy for pre-surgical use to reduce brain injury and functional decline due to surgery-related cerebral injury.
Collapse
MESH Headings
- Administration, Oral
- Animals
- Behavior, Animal/drug effects
- Brain/drug effects
- Brain/metabolism
- Brain/pathology
- Brain Injuries/blood
- Brain Injuries/drug therapy
- Brain Injuries/etiology
- Brain Injuries/physiopathology
- Cognition Disorders/drug therapy
- Cognition Disorders/etiology
- Erythropoietin/blood
- Erythropoietin/genetics
- Glycine/administration & dosage
- Glycine/analogs & derivatives
- Glycine/pharmacokinetics
- Glycine/pharmacology
- Glycine/therapeutic use
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Infarction, Middle Cerebral Artery/blood
- Infarction, Middle Cerebral Artery/complications
- Infarction, Middle Cerebral Artery/pathology
- Infarction, Middle Cerebral Artery/physiopathology
- Male
- Motor Activity/drug effects
- Organ Specificity/drug effects
- Prolyl Hydroxylases/metabolism
- Prolyl-Hydroxylase Inhibitors/administration & dosage
- Prolyl-Hydroxylase Inhibitors/pharmacology
- Prolyl-Hydroxylase Inhibitors/therapeutic use
- Quinolones/administration & dosage
- Quinolones/pharmacokinetics
- Quinolones/pharmacology
- Quinolones/therapeutic use
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Sprague-Dawley
- Sensation/drug effects
- Stroke/blood
- Stroke/complications
- Stroke/physiopathology
- Vascular Endothelial Growth Factor A/blood
- Vascular Endothelial Growth Factor A/genetics
Collapse
Affiliation(s)
- Jin Zhou
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
| | - Jie Li
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
| | - Daniel M. Rosenbaum
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
- Robert F. Furchgott Foundation, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
- Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
| | - Jian Zhuang
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
| | - Carrie Poon
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
| | - Pu Qin
- Cardiac Biology, Heart Failure Discovery Performance Unit, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania, United States of America
| | - Katrina Rivera
- Cardiac Biology, Heart Failure Discovery Performance Unit, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania, United States of America
| | - John Lepore
- Cardiac Biology, Heart Failure Discovery Performance Unit, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania, United States of America
| | - Robert N. Willette
- Cardiac Biology, Heart Failure Discovery Performance Unit, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania, United States of America
| | - Erding Hu
- Cardiac Biology, Heart Failure Discovery Performance Unit, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania, United States of America
| | - Frank C. Barone
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
- Robert F. Furchgott Foundation, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
- Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
- * E-mail:
| |
Collapse
|
18
|
Nath M, Wagshul ME, Ferbinteanu J, Rosenbaum DM, Selvan P, Anyanwu C, Li J, Barone FC. Abstract TMP97: Demyelination, Cognition and Imaging in a Translational Model of Rat Vascular Cognitive Impairment. Stroke 2017. [DOI: 10.1161/str.48.suppl_1.tmp97] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Small vessel disease and/or atherosclerosis produce microvascular and parenchymal inflammation in white matter and results in vascular cognitive impairment (VCI). We have performed bilateral carotid artery stenosis in hypertensive rats (SHR) to better understand disease pathology, targets for intervention and markers.
Hypothesis:
Complex cognitive deficits and diffuse fiber tract changes relevant to human VCI can be quantified and validated for future use.
Methodology:
We performed a series of behavioral assays to test declarative memory and executive functioning in stenosis compared to sham surgery SHR. Behavioral assays included T-maze decision making and alternation, novel object recognition (NOR) and active place avoidance (APA). MRI (DTI, DWI, Arterial Spin Labeling; ASL) and FDG-PET imaging was done in Corpus Callosum (CC). Histology-immunohistochemistry included measurements of microglia (Iba-1), astrocytes (GFAP) and Luxol fast blue (for myelin) in CC.
Results:
Stenosis resulted in consistent executive function decision making (T-maze) deficits (p<0.05) and impaired complex cognitive performance (APA). No significant differences occurred between sham and stenosis animals in NOR and T-maze alternation. DTI analysis indicated significant (p<0.05) changes in the CC of stenosis compared to sham SHR including: (1) decreased fractional anisotropy, (2) increased radial diffusivity, and (3) unchanged axial diffusivity. MRI ASL revealed significant (p<0.05) decreases in white matter perfusion. No significant changes were seen in FDG-PET. In summary, stenosis animals exhibited increased white matter glial cell inflammation related to demyelination and lost cognition. The inflammatory microglia phenotype was verified using TNFα plus Iba-1 double staining. CC changes were significantly (p<0.05) greater in the anterior, periventricular forebrain.
Conclusion:
We have successfully modeled the behavioral, imaging and histologic profile of human VCI in the rat. Currently pre/mature oligodendrocyte changes are being evaluated. This approach provides future opportunities to localize forebrain white matter changes using MR imaging parameters as markers for monitoring VCI demyelination/pathology and intervention.
Collapse
Affiliation(s)
- Manan Nath
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | - Mark E Wagshul
- Dept of Radiology, Dept of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY
| | | | | | | | | | - Jie Li
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | | |
Collapse
|
19
|
Abstract
The human orexin/hypocretin receptors (hOX1R and hOX2R) are G protein-coupled receptors (GPCRs) that mediate the diverse functions of the orexin/hypocretin neuropeptides. Orexins/hypocretins produced by neurons in the lateral hypothalamus stimulate their cognate GPCRs in multiple regions of the central nervous system to control sleep and arousal, circadian rhythms, metabolism, reward pathways, and other behaviors. Dysfunction of orexin/hypocretin signaling is associated with human disease, and the receptors are active targets in a number of therapeutic areas. To better understand the molecular mechanism of the orexin/hypocretin neuropeptides, high-resolution three-dimensional structures of hOX1R and hOX2R are critical. We have solved high-resolution crystal structures of both human orexin/hypocretin receptors bound to high-affinity antagonists. These atomic structures have elucidated how different small molecule antagonists bind with high potency and selectivity, and have also provided clues as to how the native ligands may associate with their receptors. The orexin/hypocretin receptor coordinates, now available to the broader academic and drug discovery community, will facilitate rational design of new therapeutics that modulate orexin/hypocretin signaling in humans.
Collapse
Affiliation(s)
- Jie Yin
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| |
Collapse
|
20
|
Shao Z, Yin J, Chapman K, Grzemska M, Clark L, Wang J, Rosenbaum DM. High-resolution crystal structure of the human CB1 cannabinoid receptor. Nature 2016; 540:602-606. [PMID: 27851727 PMCID: PMC5433929 DOI: 10.1038/nature20613] [Citation(s) in RCA: 289] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 11/08/2016] [Indexed: 12/21/2022]
Abstract
The human cannabinoid G-protein-coupled receptors (GPCRs) CB1 and CB2 mediate the functional responses to the endocannabinoids anandamide and 2-arachidonyl glycerol (2-AG) and to the widely consumed plant phytocannabinoid Δ9-tetrahydrocannabinol (THC). The cannabinoid receptors have been the targets of intensive drug discovery efforts, because modulation of these receptors has therapeutic potential to control pain, epilepsy, obesity, and other disorders. Although much progress in understanding the biophysical properties of GPCRs has recently been made, investigations of the molecular mechanisms of the cannabinoids and their receptors have lacked high-resolution structural data. Here we report the use of GPCR engineering and lipidic cubic phase crystallization to determine the structure of the human CB1 receptor bound to the inhibitor taranabant at 2.6-Å resolution. We found that the extracellular surface of CB1, including the highly conserved membrane-proximal N-terminal region, is distinct from those of other lipid-activated GPCRs, forming a critical part of the ligand-binding pocket. Docking studies further demonstrate how this same pocket may accommodate the cannabinoid agonist THC. Our CB1 structure provides an atomic framework for studying cannabinoid receptor function and will aid the design and optimization of therapeutic modulators of the endocannabinoid system.
Collapse
Affiliation(s)
- Zhenhua Shao
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Jie Yin
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Karen Chapman
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Magdalena Grzemska
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Lindsay Clark
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Junmei Wang
- Green Center for Systems Biology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Daniel M. Rosenbaum
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| |
Collapse
|
21
|
Abstract
Global and focal ischemias induce a variety of gene families, including immediate early genes, cytokines, neurotransmitter receptors, and heat-shock proteins. The Janus-like effects of several of these gene prod ucts promote neuronal survival and degeneration. Therefore, determining the molecular pathways respon sible for the differential regulation of these genes is of paramount importance. The discovery of apoptosis as a mediator of delayed neuronal death has led to the identification of a number of other genes involved in postischemic brain damage. Future neuroprotective therapies for cerebral ischemia may be directed at preventing alterations in gene expression. NEUROSCIENTIST 5:238-253, 1999
Collapse
Affiliation(s)
- Sean I. Savitz
- Department of Neurology, Neuroscience, Albert Einstein
College of Medicine Bronx, New York
| | - Daniel M. Rosenbaum
- Department of Neurology, Neuroscience and Ophthalmology
Albert Einstein College of Medicine Bronx, New York
| |
Collapse
|
22
|
Zhang Y, Lee KM, Kinch LN, Clark L, Grishin NV, Rosenbaum DM, Brown MS, Goldstein JL, Radhakrishnan A. Direct Demonstration That Loop1 of Scap Binds to Loop7: A CRUCIAL EVENT IN CHOLESTEROL HOMEOSTASIS. J Biol Chem 2016; 291:12888-12896. [PMID: 27068746 DOI: 10.1074/jbc.m116.729798] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 11/06/2022] Open
Abstract
Cholesterol homeostasis is mediated by Scap, a polytopic endoplasmic reticulum (ER) protein that transports sterol regulatory element-binding proteins from the ER to Golgi, where they are processed to forms that activate cholesterol synthesis. Scap has eight transmembrane helices and two large luminal loops, designated Loop1 and Loop7. We earlier provided indirect evidence that Loop1 binds to Loop7, allowing Scap to bind COPII proteins for transport in coated vesicles. When ER cholesterol rises, it binds to Loop1. We hypothesized that this causes dissociation from Loop7, abrogating COPII binding. Here we demonstrate direct binding of the two loops when expressed as isolated fragments or as a fusion protein. Expressed alone, Loop1 remained intracellular and membrane-bound. When Loop7 was co-expressed, it bound to Loop1, and the soluble complex was secreted. A Loop1-Loop7 fusion protein was also secreted, and the two loops remained bound when the linker between them was cleaved by a protease. Point mutations that disrupt the Loop1-Loop7 interaction prevented secretion of the Loop1-Loop7 fusion protein. These data provide direct documentation of intramolecular Loop1-Loop7 binding, a central event in cholesterol homeostasis.
Collapse
Affiliation(s)
| | | | - Lisa N Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | | | - Nick V Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Biophysics, and; Biochemistry and
| | | | | | | | | |
Collapse
|
23
|
Yin J, Babaoglu K, Brautigam CA, Clark L, Shao Z, Scheuermann TH, Harrell CM, Gotter AL, Roecker AJ, Winrow CJ, Renger JJ, Coleman PJ, Rosenbaum DM. Structure and ligand-binding mechanism of the human OX1 and OX2 orexin receptors. Nat Struct Mol Biol 2016; 23:293-9. [PMID: 26950369 DOI: 10.1038/nsmb.3183] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 02/02/2016] [Indexed: 01/10/2023]
Abstract
The orexin (also known as hypocretin) G protein-coupled receptors (GPCRs) regulate sleep and other behavioral functions in mammals, and are therapeutic targets for sleep and wake disorders. The human receptors hOX1R and hOX2R, which are 64% identical in sequence, have overlapping but distinct physiological functions and potential therapeutic profiles. We determined structures of hOX1R bound to the OX1R-selective antagonist SB-674042 and the dual antagonist suvorexant at 2.8-Å and 2.75-Å resolution, respectively, and used molecular modeling to illuminate mechanisms of antagonist subtype selectivity between hOX1R and hOX2R. The hOX1R structures also reveal a conserved amphipathic α-helix, in the extracellular N-terminal region, that interacts with orexin-A and is essential for high-potency neuropeptide activation at both receptors. The orexin-receptor crystal structures are valuable tools for the design and development of selective orexin-receptor antagonists and agonists.
Collapse
Affiliation(s)
- Jie Yin
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kerim Babaoglu
- Department of Structural Chemistry, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - Chad A Brautigam
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Lindsay Clark
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Zhenhua Shao
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Thomas H Scheuermann
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Charles M Harrell
- Department of Neuroscience, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - Anthony L Gotter
- Department of Neuroscience, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - Anthony J Roecker
- Department of Medicinal Chemistry, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - Christopher J Winrow
- Department of Neuroscience, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - John J Renger
- Department of Neuroscience, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - Paul J Coleman
- Department of Medicinal Chemistry, Merck Research Laboratories, West Point, Pennsylvania, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| |
Collapse
|
24
|
Clark L, Zahm JA, Ali R, Kukula M, Bian L, Patrie SM, Gardner KH, Rosen MK, Rosenbaum DM. Erratum to: Methyl labeling and TROSY NMR spectroscopy of proteins expressed in the eukaryote Pichia pastoris. J Biomol NMR 2016; 64:267. [PMID: 26894386 PMCID: PMC5407190 DOI: 10.1007/s10858-016-0016-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Lindsay Clark
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jacob A Zahm
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Rustam Ali
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Maciej Kukula
- Shimadzu Center for Advanced Analytical Chemistry, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Liangqiao Bian
- Shimadzu Center for Advanced Analytical Chemistry, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Steven M Patrie
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Kevin H Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, NY, 10031, USA
| | - Michael K Rosen
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
25
|
Clark L, Zahm JA, Ali R, Kukula M, Bian L, Patrie SM, Gardner KH, Rosen MK, Rosenbaum DM. Methyl labeling and TROSY NMR spectroscopy of proteins expressed in the eukaryote Pichia pastoris. J Biomol NMR 2015; 62:239-45. [PMID: 26025061 PMCID: PMC4496254 DOI: 10.1007/s10858-015-9939-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/27/2015] [Indexed: 05/03/2023]
Abstract
(13)C Methyl TROSY NMR spectroscopy has emerged as a powerful method for studying the dynamics of large systems such as macromolecular assemblies and membrane proteins. Specific (13)C labeling of aliphatic methyl groups and perdeuteration has been limited primarily to proteins expressed in E. coli, preventing studies of many eukaryotic proteins of physiological and biomedical significance. We demonstrate the feasibility of efficient (13)C isoleucine δ1-methyl labeling in a deuterated background in an established eukaryotic expression host, Pichia pastoris, and show that this method can be used to label the eukaryotic protein actin, which cannot be expressed in bacteria. This approach will enable NMR studies of previously intractable targets.
Collapse
Affiliation(s)
- Lindsay Clark
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas TX 75390 USA
| | - Jacob A. Zahm
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas TX 75390 USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Rustam Ali
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas TX 75390 USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Maciej Kukula
- Shimadzu Center for Advanced Analytical Chemistry, University of Texas at Arlington, Arlington TX 76019 USA
| | - Liangqiao Bian
- Shimadzu Center for Advanced Analytical Chemistry, University of Texas at Arlington, Arlington TX 76019 USA
| | - Steven M. Patrie
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas TX 75390 USA
| | - Kevin H. Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, NY 10031
| | - Michael K. Rosen
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas TX 75390 USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Daniel M. Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas TX 75390 USA
- Corresponding Author
| |
Collapse
|
26
|
Rosenbaum DM, Zhou J, Zhang H, Li J, Zhuang J, Poon C, Poon C, Barone FC. Abstract T P205: Thrombopoietin Reduces Brain Injury and Cognitive Impairment in Rodent Cerebrovascular Disease Models. Stroke 2014. [DOI: 10.1161/str.45.suppl_1.tp205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives:
Thrombopoietin (TPO) reduces brain injury and sensory-motor deficits following stroke in the rat. TPO brain protection is mediated by vascular protection. TPO reduces stroke-induced inflammatory cytokines, matrix metalloproteinase’s and blood brain barrier injury. Here we demonstrate that TPO protects the brain and reduces vascular cognitive impairment in: [1] rat embolic stroke (+/- tissue plasminogen activator; tPA), [2] mouse suture-focal stroke, and [3] mouse chronic carotid stenosis-induced forebrain hypoperfusion.
Methods:
Rats (Wistar) underwent embolic middle cerebral artery occlusion (MCAO). Vehicle, tPA (10 mg/kg, iv), TPO (0.1 μg/kg, iv) or TPO plus tPA were administered 2 hours post-stroke. Mice (C57Bl/6) underwent suture-MCAO or carotid artery stenosis-induced forebrain hypoperfusion and then received Vehicle or TPO (0.3 or 0.1 μg/kg, iv) at 1 hr or 1 day after surgery. Neurological deficits, complex learning and hemispheric infarct size were measured for 1-21 days post-surgery.
Results:
In rat embolic stroke, tPA or TPO plus tPA improved stroke-induced neurological deficits significantly. Significant post-stroke-induced deficits in APA cognitive performance were improved 87.2±16.4% by TPO or 69.4±9.7% by TPO plus tPA, but not by tPA alone. In mouse suture-focal stroke, brain infarcts were reduced by 64.5±7.7% and neurological deficits were reduced by 90.3±6.4%. In mouse carotid artery stenosis-induced forebrain hypoperfusion a single administration of TPO 1 day after surgery improved APA performance 84.8+3.1% 3 weeks later (all p<0.01).
Conclusions:
We have demonstrated TPO long-term protection and safety with and without tPA. TPO exhibits protection in mouse suture-focal and in mouse forebrain hypoperfusion-induced complex learning deficits. These data present multiple model and species work that supports the potential “multiple use” of TPO in the future.
Collapse
Affiliation(s)
| | - Jin Zhou
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | - Haiyan Zhang
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | - Jie Li
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | - Jiang Zhuang
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | - Carrie Poon
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | - Carrie Poon
- Neurology, SUNY Downstate Med Cntr, Brooklyn, NY
| | | |
Collapse
|
27
|
Bender KW, Rosenbaum DM, Vanderbeld B, Ubaid M, Snedden WA. The Arabidopsis calmodulin-like protein, CML39, functions during early seedling establishment. Plant J 2013; 76:634-47. [PMID: 24033804 DOI: 10.1111/tpj.12323] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/26/2013] [Accepted: 09/02/2013] [Indexed: 05/10/2023]
Abstract
During Ca(2+) signal transduction, Ca(2+)-binding proteins known as Ca(2+) sensors function to decode stimulus-specific Ca(2+) signals into downstream responses. Plants possess extended families of unique Ca(2+) sensors termed calmodulin-like proteins (CMLs) whose cellular roles are not well understood. CML39 encodes a predicted Ca(2+) sensor whose expression is strongly increased in response to diverse external stimuli. In the present study, we explored the biochemical properties of recombinant CML39, and used a reverse genetics approach to investigate its physiological role. Our data indicate that Ca(2+) binding by CML39 induces a conformational change in the protein that results in an increase in exposed-surface hydrophobicity, a property that is consistent with its predicted function as a Ca(2+) sensor. Loss-of-function cml39 mutants resemble wild-type plants under normal growth conditions but exhibit persistent arrest at the seedling stage if grown in the absence of sucrose or other metabolizable carbon sources. Under short-day conditions, cml39 mutants display increased sucrose-induced hypocotyl elongation. When grown in the dark, cml39 mutants show impaired hypocotyl elongation in the absence of sucrose. Promoter-reporter data indicate that CML39 expression is prominent in the apical hook in dark-grown seedlings. Collectively, our data suggest that CML39 functions in Arabidopsis as a Ca(2+) sensor that plays an important role in the transduction of light signals that promote seedling establishment.
Collapse
Affiliation(s)
- Kyle W Bender
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada
| | | | | | | | | |
Collapse
|
28
|
Zhou J, Zhuang J, Li J, Ooi E, Bloom J, Poon C, Lax D, Rosenbaum DM, Barone FC. Long-term post-stroke changes include myelin loss, specific deficits in sensory and motor behaviors and complex cognitive impairment detected using active place avoidance. PLoS One 2013; 8:e57503. [PMID: 23505432 PMCID: PMC3591420 DOI: 10.1371/journal.pone.0057503] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 01/22/2013] [Indexed: 12/14/2022] Open
Abstract
Persistent neurobehavioral deficits and brain changes need validation for brain restoration. Two hours middle cerebral artery occlusion (tMCAO) or sham surgery was performed in male Sprague-Dawley rats. Neurobehavioral and cognitive deficits were measured over 10 weeks included: (1) sensory, motor, beam balance, reflex/abnormal responses, hindlimb placement, forepaw foot fault and cylinder placement tests, and (2) complex active place avoidance learning (APA) and simple passive avoidance retention (PA). Electroretinogram (ERG), hemispheric loss (infarction), hippocampus CA1 neuronal loss and myelin (Luxol Fast Blue) staining in several fiber tracts were also measured. In comparison to Sham surgery, tMCAO surgery produced significant deficits in all behavioral tests except reflex/abnormal responses. Acute, short lived deficits following tMCAO were observed for forelimb foot fault and forelimb cylinder placement. Persistent, sustained deficits for the whole 10 weeks were exhibited for motor (p<0.001), sensory (p<0.001), beam balance performance (p<0.01) and hindlimb placement behavior (p<0.01). tMCAO produced much greater and prolonged cognitive deficits in APA learning (maximum on last trial of 604±83% change, p<0.05) but only a small, comparative effect on PA retention. Hemispheric loss/atrophy was measured 10 weeks after tMCAO and cross-validated by two methods (e.g., almost identical % ischemic hemispheric loss of 33.4±3.5% for H&E and of 34.2±3.5% for TTC staining). No visual dysfunction by ERG and no hippocampus neuronal loss were detected after tMCAO. Fiber tract damage measured by Luxol Fast Blue myelin staining intensity was significant (p<0.01) in the external capsule and striatum but not in corpus callosum and anterior commissure. In summary, persistent neurobehavioral deficits were validated as important endpoints for stroke restorative research in the future. Fiber myelin loss appears to contribute to these long term behavioral dysfunctions and can be important for cognitive behavioral control necessary for complex APA learning.
Collapse
Affiliation(s)
- Jin Zhou
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America.
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Berger JS, McGinn AP, Howard BV, Kuller L, Manson JE, Otvos J, Curb JD, Eaton CB, Kaplan RC, Lynch JK, Rosenbaum DM, Wassertheil-Smoller S. Lipid and lipoprotein biomarkers and the risk of ischemic stroke in postmenopausal women. Stroke 2012; 43:958-66. [PMID: 22308251 DOI: 10.1161/strokeaha.111.641324] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Few studies simultaneously investigated lipids and lipoprotein biomarkers as predictors of ischemic stroke. The value of these biomarkers as independent predictors of ischemic stroke remains controversial. METHODS We conducted a prospective nested case-control study among postmenopausal women from the Women's Health Initiative Observational Study to assess the relationship between fasting lipids (total cholesterol, low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], and triglycerides), lipoproteins (LDL, HDL, and very low-density lipoprotein [VLDL] particle number and size, intermediate-density lipoprotein [IDL] particle number, and lipoprotein (a)), and risk of ischemic stroke. Among women free of stroke at baseline, 774 ischemic stroke patients were matched according to age and race to control subjects, using a 1:1 ratio. RESULTS In bivariate analysis, baseline triglycerides (P<0.001), IDL particles (P<0.01), LDL particles (P<0.01), VLDL triglyceride (P<0.001), VLDL particles (P<0.01), VLDL size (P<0.001), LDL size (P=0.03), and total/HDL cholesterol ratio (P<0.01) were significantly higher among women with incident ischemic stroke, whereas levels of HDL-C (P<0.01) and HDL size (P<0.01) were lower. No significant baseline difference for total cholesterol (P=0.15), LDL-C (P=0.47), and lipoprotein (a) (P=0.11) was observed. In multivariable analysis, triglycerides (odds ratio for the highest versus lowest quartile, 1.56; 95% confidence interval, 1.13-2.17; P for trend=0.02), VLDL size (odds ratio, 1.59; 95% confidence interval, 1.10-2.28; P for trend=0.03), and IDL particle number (odds ratio, 1.46; 95% confidence interval, 1.04-2.04; P for trend=0.02) were significantly associated with ischemic stroke. CONCLUSIONS Among a panel of lipid and lipoprotein biomarkers, baseline triglycerides, VLDL size, and IDL particle number were significantly associated with incident ischemic stroke in postmenopausal women.
Collapse
Affiliation(s)
- Jeffrey S Berger
- FAHA, New York University School of Medicine, 530 First Ave, Skirball 9R, New York, NY 10016, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Malhotra S, Naggar I, Stewart M, Rosenbaum DM. Neurogenic pathway mediated remote preconditioning protects the brain from transient focal ischemic injury. Brain Res 2011; 1386:184-90. [DOI: 10.1016/j.brainres.2011.02.032] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 02/07/2011] [Accepted: 02/14/2011] [Indexed: 01/24/2023]
|
31
|
Rasmussen SGF, Choi HJ, Fung JJ, Pardon E, Casarosa P, Chae PS, Devree BT, Rosenbaum DM, Thian FS, Kobilka TS, Schnapp A, Konetzki I, Sunahara RK, Gellman SH, Pautsch A, Steyaert J, Weis WI, Kobilka BK. Structure of a nanobody-stabilized active state of the β(2) adrenoceptor. Nature 2011; 469:175-80. [PMID: 21228869 PMCID: PMC3058308 DOI: 10.1038/nature09648] [Citation(s) in RCA: 1301] [Impact Index Per Article: 100.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 11/01/2010] [Indexed: 11/16/2022]
Abstract
G protein coupled receptors (GPCRs) exhibit a spectrum of functional behaviors in response to natural and synthetic ligands. Recent crystal structures provide insights into inactive states of several GPCRs. Efforts to obtain an agonist-bound active-state GPCR structure have proven difficult due to the inherent instability of this state in the absence of a G protein. We generated a camelid antibody fragment (nanobody) to the human β2 adrenergic receptor (β2AR) that exhibits G protein-like behavior, and obtained an agonist-bound, active-state crystal structure of the receptor-nanobody complex. Comparison with the inactive β2AR structure reveals subtle changes in the binding pocket; however, these small changes are associated with an 11Å outward movement of the cytoplasmic end of transmembrane segment 6, and rearrangements of transmembrane segments 5 and 7 that are remarkably similar to those observed in opsin, an active form of rhodopsin. This structure provides insights into the process of agonist binding and activation.
Collapse
Affiliation(s)
- Søren G F Rasmussen
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, California 94305, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Rosenbaum DM, Zhang C, Lyons JA, Holl R, Aragao D, Arlow DH, Rasmussen SGF, Choi HJ, Devree BT, Sunahara RK, Chae PS, Gellman SH, Dror RO, Shaw DE, Weis WI, Caffrey M, Gmeiner P, Kobilka BK. Structure and function of an irreversible agonist-β(2) adrenoceptor complex. Nature 2011; 469:236-40. [PMID: 21228876 PMCID: PMC3074335 DOI: 10.1038/nature09665] [Citation(s) in RCA: 612] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 11/11/2010] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are eukaryotic integral membrane proteins that modulate biological function by initiating cellular signaling in response to chemically diverse agonists. Despite recent progress in the structural biology of GPCRs1, the molecular basis for agonist binding and allosteric modulation of these proteins is poorly understood. Structural knowledge of agonist-bound states is essential for deciphering the mechanism of receptor activation, and for structure-guided design and optimization of ligands. However, the crystallization of agonist-bound GPCRs has been hampered by modest affinities and rapid off-rates of available agonists. Using the inactive structure of the human β2 adrenergic receptor (β2AR) as a guide, we designed a β2AR agonist that can be covalently tethered to a specific site on the receptor through a disulfide bond. The covalent β2AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound β2AR-T4L fusion protein in lipid bilayers through the use of the lipidic mesophase method2, and determined its structure at 3.5 Å resolution. A comparison to the inactive structure and an antibody-stabilized active structure (companion paper3) shows how binding events at both the extracellular and intracellular surfaces are required to stabilize an active conformation of the receptor. The structures are in agreement with long-timescale (up to 30 μs) molecular dynamics simulations showing that an agonist-bound active conformation spontaneously relaxes to an inactive-like conformation in the absence of a G protein or stabilizing antibody.
Collapse
Affiliation(s)
- Daniel M Rosenbaum
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, California 94305, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Rosenbaum DM, Degterev A, David J, Rosenbaum PS, Roth S, Grotta JC, Cuny GD, Yuan J, Savitz SI. Necroptosis, a novel form of caspase-independent cell death, contributes to neuronal damage in a retinal ischemia-reperfusion injury model. J Neurosci Res 2010; 88:1569-76. [PMID: 20025059 DOI: 10.1002/jnr.22314] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
UNLABELLED Necroptosis is programmed necrosis triggered by death receptor signaling. We investigated whether necroptosis contributes to neuronal damage and functional impairment in a model of retinal ischemia. METHODS Sprague-Dawley rats were subjected to raised intra-ocular pressure for 45 min and received intravitreal injections of the specific necroptosis inhibitor, Nec-1, its inactive analogue (Nec-1i) or vehicle. Seven days after ischemia, ERGs were performed and then the eyes were enucleated for histological analysis. In other animals, retinas were subjected to propodium iodide, TUNEL staining or Western Blotting and probed with anti-LC-3 antibody. RESULTS Retinal ischemia resulted in selective neuronal degeneration of the inner layers. Pretreatment with Nec-1 led to significant preservation in thickness and histoarchitecture of the inner retina and functional improvement compared with vehicle-treated controls. Pretreatment with Nec-1i did not provide histological or functional protection. Post-treatment with Nec-1 also significantly attenuated the ERG b-wave reduction compared with ischemic vehicle controls. Nec-1 had no effect on the number of caspase or TUNEL-labelled cells in the ischemic retina but did inhibit the induction of LC-3 II and reduced the number of PI-labelled cells after ischemia. CONCLUSION Necroptosis is an important mode of neuronal cell death and involves autophagy in a model of retinal ischemia.
Collapse
Affiliation(s)
- Daniel M Rosenbaum
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Barone FC, Rosenbaum DM, Zhou J, Crystal H. Vascular cognitive impairment: dementia biology and translational animal models. Curr Opin Investig Drugs 2009; 10:624-637. [PMID: 19579168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Relationships between cardiovascular risk and disease, and dementia have been identified, and the term vascular cognitive impairment (VCI) is used to describe individuals with significant cognitive impairments produced by cerebrovascular disease (CVD). VCI is the second most prevalent form of dementia and is composed of a heterogeneous pathology. Risk factors for VCI are similar to those of the most prevalent form of dementia, Alzheimer's disease (AD). In addition, recent data suggest that VCI can contribute significantly to the progression of AD, and AD can contribute to VCI. Translational animal models of VCI are necessary to further understand CVD mechanisms contributing to impaired cognition. This review describes animal models of cerebrovascular insufficiency (ie, chronic hypoperfusion and hypertension) that produce experimental VCI, including their relationships to human VCI and, when appropriate, to AD. The use of these models is expected to help discover biomarkers and disease mechanism-linked targets for diagnostic and therapeutic purposes, thus facilitating early identification and intervention in VCI.
Collapse
Affiliation(s)
- Frank C Barone
- SUNY Downstate Medical Center, School of Medicine, Department of Neurology, 450 Clarkson Avenue, Box 1213, Brooklyn, NY 11225, USA.
| | | | | | | |
Collapse
|
35
|
Dreixler JC, Hemmert JW, Shenoy SK, Shen Y, Lee HT, Shaikh AR, Rosenbaum DM, Roth S. The role of Akt/protein kinase B subtypes in retinal ischemic preconditioning. Exp Eye Res 2008; 88:512-21. [PMID: 19084003 DOI: 10.1016/j.exer.2008.11.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 09/26/2008] [Accepted: 11/04/2008] [Indexed: 01/26/2023]
Abstract
Potent endogenous protection from ischemia can be induced in the retina by ischemic preconditioning (IPC). Protein kinase B/Akt is a cellular survival factor. We hypothesized that Akt was integral to IPC based upon differential effects of Akt subtypes. Rats were subjected to retinal ischemia after IPC or IPC-mimicking by the opening of mitochondrial KATP (mKATP) channels. The effects of blocking Akt using wortmannin, API-2, or small interfering RNA (siRNA) were examined. Electroretinography assessed functional recovery after ischemia, and TUNEL examined retinal ganglion cell apoptosis. We studied the relationship between Akt activation and known initiators of IPC, including adenosine receptor stimulation and the opening of mKATP channels. The PI-3 kinase inhibitor wortmannin 1 or 4 mg/kg (i.p.), the specific Akt inhibitor API-2, 5-500 microM in the vitreous, or intravitreal siRNA directed against Akt2 or -3, but not Akt1, significantly attenuated the neuroprotective effect of IPC. Interfering RNA against any of the three Akt subtypes significantly but time-dependently attenuated mKATP channel opening to mimic IPC. Adenosine A1 receptor blockade (DPCPX), A2a blockade (CSC), or the mKATP channel blocker 5-hydroxydecanoic acid significantly attenuated Akt activation after IPC. Interfering RNA directed against Akt subtypes prevented the ameliorative effect of IPC on post-ischemic apoptosis. All three Akt subtypes are involved in functional retinal neuroprotection by IPC or IPC-mimicking. Akt is downstream of adenosine A1 and A2a receptors and mKATP channel opening. The results indicate the presence in the retina of robust and redundant endogenous neuroprotection based upon subtypes of Akt.
Collapse
Affiliation(s)
- John C Dreixler
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Berger S, Savitz SI, Nijhawan S, Singh M, David J, Rosenbaum PS, Rosenbaum DM. Deleterious role of TNF-alpha in retinal ischemia-reperfusion injury. Invest Ophthalmol Vis Sci 2008; 49:3605-10. [PMID: 18660426 DOI: 10.1167/iovs.07-0817] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
PURPOSE Tumor necrosis factor (TNF)-alpha is a mediator of neuronal cell death and survival in ischemia-reperfusion injury. This study was conducted to further elucidate the role of TNF-alpha and its receptor in an in vivo model of retinal ischemia-reperfusion injury by investigating its effects on retinal histopathology and function. METHODS Retinal ischemia-reperfusion injury was performed on p55 and p75 knockout (KO) mice and Sprague-Dawley rats using the high intraocular pressure METHOD The temporal expression of TNF-alpha was ascertained with immunohistochemical staining. Separate rats received intravitreal recombinant TNF-alpha or neutralizing antibody before or after ischemia. TUNEL labeling was performed to assess for cell death, and electroretinography was performed to assess function. RESULTS TNF-alpha expression peaked at 12 to 24 hours after ischemia-reperfusion injury. TUNEL staining was diminished after intravitreal TNF-alpha antibody. Both transgenic KOs demonstrated significantly less functional impairment. Rats receiving recombinant TNF-alpha 48 hours after ischemia showed exaggerated functional impairment. Animals treated with TNF-alpha antibody before ischemia displayed significant functional improvement. CONCLUSIONS TNF-alpha plays a largely deleterious role in ischemia-reperfusion injury in an in vivo model of retinal injury. Direct neutralization of this cytokine partially preserves retinal function. The diverse characteristics of TNF-alpha are attributed in part to the timing of its expression after injury. TNF-alpha receptor expression and function, along with combination treatments targeting death receptor-mediated apoptosis, should be further explored to develop neuroprotective therapeutic strategies for acute retinal ischemic disorders.
Collapse
Affiliation(s)
- Samuel Berger
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York11203, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
McGinn AP, Kaplan RC, Verghese J, Rosenbaum DM, Psaty BM, Baird AE, Lynch JK, Wolf PA, Kooperberg C, Larson JC, Wassertheil-Smoller S. Walking Speed and Risk of Incident Ischemic Stroke Among Postmenopausal Women. Stroke 2008; 39:1233-9. [DOI: 10.1161/strokeaha.107.500850] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Aileen P. McGinn
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Robert C. Kaplan
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Joe Verghese
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Daniel M. Rosenbaum
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Bruce M. Psaty
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Alison E. Baird
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - John K. Lynch
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Philip A. Wolf
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Charles Kooperberg
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Joseph C. Larson
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| | - Sylvia Wassertheil-Smoller
- From the Departments of Epidemiology and Population Health (R.C.K., A.P.M., S.W.S.) and Neurology (J.V., D.M.R.), Albert Einstein College of Medicine, Bronx NY; Fred Hutchinson Cancer Research Center (C.K., J.C.L.), Seattle, Wash; Departments of Epidemiology, Medicine and Health Services (B.M.P.), Cardiovascular Health Research Unit, University of Washington, Seattle; National Institute of Neurological Disorders and Stroke, Stroke Neuroscience Unit (A.E.B.) and Neuroepidemiology Branch (J.K.L.),
| |
Collapse
|
38
|
Rosenbaum DM, Cherezov V, Hanson MA, Rasmussen SGF, Thian FS, Kobilka TS, Choi HJ, Yao XJ, Weis WI, Stevens RC, Kobilka BK. GPCR engineering yields high-resolution structural insights into beta2-adrenergic receptor function. Science 2007; 318:1266-73. [PMID: 17962519 DOI: 10.1126/science.1150609] [Citation(s) in RCA: 1085] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The beta2-adrenergic receptor (beta2AR) is a well-studied prototype for heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) that respond to diffusible hormones and neurotransmitters. To overcome the structural flexibility of the beta2AR and to facilitate its crystallization, we engineered a beta2AR fusion protein in which T4 lysozyme (T4L) replaces most of the third intracellular loop of the GPCR ("beta2AR-T4L") and showed that this protein retains near-native pharmacologic properties. Analysis of adrenergic receptor ligand-binding mutants within the context of the reported high-resolution structure of beta2AR-T4L provides insights into inverse-agonist binding and the structural changes required to accommodate catecholamine agonists. Amino acids known to regulate receptor function are linked through packing interactions and a network of hydrogen bonds, suggesting a conformational pathway from the ligand-binding pocket to regions that interact with G proteins.
Collapse
Affiliation(s)
- Daniel M Rosenbaum
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Cherezov V, Rosenbaum DM, Hanson MA, Rasmussen SGF, Thian FS, Kobilka TS, Choi HJ, Kuhn P, Weis WI, Kobilka BK, Stevens RC. High-resolution crystal structure of an engineered human beta2-adrenergic G protein-coupled receptor. Science 2007; 318:1258-65. [PMID: 17962520 DOI: 10.1126/science.1150577] [Citation(s) in RCA: 2537] [Impact Index Per Article: 149.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors constitute the largest family of eukaryotic signal transduction proteins that communicate across the membrane. We report the crystal structure of a human beta2-adrenergic receptor-T4 lysozyme fusion protein bound to the partial inverse agonist carazolol at 2.4 angstrom resolution. The structure provides a high-resolution view of a human G protein-coupled receptor bound to a diffusible ligand. Ligand-binding site accessibility is enabled by the second extracellular loop, which is held out of the binding cavity by a pair of closely spaced disulfide bridges and a short helical segment within the loop. Cholesterol, a necessary component for crystallization, mediates an intriguing parallel association of receptor molecules in the crystal lattice. Although the location of carazolol in the beta2-adrenergic receptor is very similar to that of retinal in rhodopsin, structural differences in the ligand-binding site and other regions highlight the challenges in using rhodopsin as a template model for this large receptor family.
Collapse
Affiliation(s)
- Vadim Cherezov
- Department of Molecular Biology, Scripps Research Institute, La Jolla, CA 92037, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Rasmussen SGF, Choi HJ, Rosenbaum DM, Kobilka TS, Thian FS, Edwards PC, Burghammer M, Ratnala VRP, Sanishvili R, Fischetti RF, Schertler GFX, Weis WI, Kobilka BK. Crystal structure of the human β2 adrenergic G-protein-coupled receptor. Nature 2007; 450:383-7. [PMID: 17952055 DOI: 10.1038/nature06325] [Citation(s) in RCA: 1415] [Impact Index Per Article: 83.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Accepted: 09/28/2007] [Indexed: 11/10/2022]
|
41
|
Abstract
Caveolins (Cav), the principal structural proteins of the caveolar domains, have been implicated in the pathogenesis of ischemic injury. Indeed, changes in caveolin expression and localization have been reported in renal and myocardial ischemia. Genetic ablation of the Cav-1 gene in mice was further shown to increase the extent of ischemic injury in a model of hindlimb ischemia. However, the role of Cav-1 in the pathogenesis of cerebral ischemia remains unknown. Immunoblot and immunofluorescence analyses of rat brains subjected to middle cerebral artery occlusion revealed marked increases in endothelial Cav-1 and Cav-2 protein levels. To directly assess the functional role of caveolins in the pathogenesis of cerebral ischemic injury, we next investigated the effects of cerebral ischemia in caveolin knockout (KO) mice. Interestingly, Cav-1 KO mice showed a marked increase of cerebral volume of infarction, as compared with wild-type and Cav-2 KO mice. Immunofluorescence analyses showed an increased number of proliferating endothelial cells in wild-type ischemic brains, as compared with Cav-1 KO ischemic brains. Immunoblot analyses of wild-type ischemic brains showed an increase in endothelial nitric oxide synthase protein levels. Conversely, the protein levels of endothelial nitric oxide synthase remained unchanged in Cav-1 KO ischemic brains. TUNEL analysis also showed increased apoptotic cell death in Cav-1 KO ischemic brains, as compared with wild-type ischemic brains. Our findings indicate cerebral ischemia induces a marked increase in endothelial Cav-1 and Cav-2 protein levels. Importantly, genetic ablation of the Cav-1 gene in mice results in increased cerebral volume of infarction. Mechanistically, Cav-1 KO ischemic brains showed impaired angiogenesis and increased apoptotic cell death.
Collapse
Affiliation(s)
- Jean-François Jasmin
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | | | | | | | | | | |
Collapse
|
42
|
Savitz SI, Dhallu MS, Malhotra S, Mammis A, Ocava LC, Rosenbaum PS, Rosenbaum DM. EDG receptors as a potential therapeutic target in retinal ischemia-reperfusion injury. Brain Res 2006; 1118:168-75. [PMID: 17026968 DOI: 10.1016/j.brainres.2006.05.060] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 05/17/2006] [Accepted: 05/19/2006] [Indexed: 11/21/2022]
Abstract
LPA (lysophosphatidic acid) specific endothelial differentiation gene (EDG) receptors have been implicated in various anti-apoptotic pathways. Ischemia of the brain and retina causes neuronal apoptosis, which raises the possibility that EDG receptors participate in anti-apoptotic signaling in ischemic injury. We examined the expression of EDG receptors in a model of retinal ischemia-reperfusion injury and also tested LXR-1035, a novel analogue of LPA, in the rat following global retinal ischemic injury. Rats were subjected to 45 or 60 min of raised intraocular pressure. Animals were sacrificed at 24 h post-ischemia and retinal tissue was stained for EDG receptors. In separate experiments, animals were randomized to receive LXR or saline vehicle by intravitreal injection 24 h prior to ischemia. The degree of retinal damage was assessed morphologically by measuring the thickness of the inner retinal layers as well as functionally by electroretinography (ERG). We found that the normal retina has a baseline expression of the LPA receptors, EDG-2 and EDG-4, which are significantly upregulated in the inner layers in response to ischemia. Animals pretreated with LXR-1035 had dose-dependent, significant reductions in histopathologic damage and significant improvement in functional deficits compared with corresponding vehicle-controls, after 45 and 60 min of ischemia. These results suggest that LPA receptor signaling may play an important role in neuroprotection in retinal ischemia-reperfusion injury.
Collapse
Affiliation(s)
- Sean I Savitz
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, USA.
| | | | | | | | | | | | | |
Collapse
|
43
|
Phillips KJ, Rosenbaum DM, Liu DR. Binding and Stability Determinants of the PPARγ Nuclear Receptor−Coactivator Interface As Revealed by Shotgun Alanine Scanning and in Vivo Selection. J Am Chem Soc 2006; 128:11298-306. [PMID: 16925449 DOI: 10.1021/ja0635985] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We modified an existing selection for protein-protein interactions based on the fragment complementation of the enzyme DHFR. Using shotgun alanine scanning in conjunction with this selection, we analyzed the interaction of the nuclear receptor PPARgamma with two peptides derived from nuclear receptor coactivators SRC1 and TRAP220. A large binding epitope stretching between and including the charge clamp residues K301 and E471 of PPARgamma was identified as necessary for PPARgamma-coactivator interaction. To decouple protein stability from the propensity to form a receptor-coactivator interface, libraries of PPARgamma variants generated by shotgun scanning were further processed using a high-throughput screen measuring their in vivo stabilities. Our findings demonstrate that many of the residues that make up the binding epitope of PPARgamma are also crucial for the stability of the PPARgamma.
Collapse
Affiliation(s)
- Kevin J Phillips
- Department of Chemistry and Chemical Biology, Howard Hughes Medical Institute, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
| | | | | |
Collapse
|
44
|
Malhotra S, Savitz SI, Ocava L, Rosenbaum DM. Ischemic preconditioning is mediated by erythropoietin through PI-3 kinase signaling in an animal model of transient ischemic attack. J Neurosci Res 2006; 83:19-27. [PMID: 16307446 DOI: 10.1002/jnr.20705] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ischemic preconditioning (IP) protects the brain from subsequent, prolonged, and lethal ischemia in experimental studies. Erythropoietin (EPO) participates in the brain's intrinsic response to injury and may play a role in preconditioning. By using a middle cerebral artery occlusion (MCAo) model of transient ischemic attack (TIA), we sought to determine whether EPO is required for IP in the protective response against focal ischemic stroke. Rats underwent three 10-min MCA occlusions or sham surgery. Three days later, animals underwent 2 hr of MCAo and 22 hr of reperfusion. Experimental TIAs reduced infarct volumes by 55% (P < 0.05), inhibited DNA fragmentation, and improved neurological outcome by 50% (P < 0.05) after ischemic stroke. EPO and its receptor were up-regulated by IP in the ipsilateral hemisphere by 24 hr after IP, before ischemic stroke and soluble EPO receptor attenuated neuroprotection by IP (88% reduction, P < 0.05). Pretreatment with the PI-3 kinase inhibitor wortmannin abolished the protective effect of IP against ischemic injury (P < 0.05). IP may be mediated in part by EPO through a PI-3 kinase pathway.
Collapse
Affiliation(s)
- Samit Malhotra
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, USA
| | | | | | | |
Collapse
|
45
|
Abstract
Thrombolytic and antithrombotic agents form the cornerstone of stroke treatment and prevention. Recombinant tissue plasminogen activator improves outcome in patients treated within 3 hours of stroke onset. Emerging trials are directed to extend the therapeutic window and identify agents that could provide better safety profiles. Large, randomized trials have also highlighted the effectiveness and safety of early and continuous antiplatelet therapy in reducing atherothrombotic stroke recurrence. Aspirin has become the antiplatelet treatment standard against which several other antiplatelet agents have been shown to be more effective. The prevention of cardioembolic stroke is best accomplished with oral anticoagulation, barring any contraindications.
Collapse
Affiliation(s)
- Lenore C Ocava
- Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | | | | |
Collapse
|
46
|
Abstract
Increasing experimental evidence suggests that cell transplantation can enhance recovery from stroke in animal models of focal cerebral ischemia. Clinical trials have been investigating the effects of a human immortalized neuronal cell line and porcine fetal neurons in stroke victims with persistent and stable deficits. Preclinical studies are focusing on the effects of human stem cells from various sources including brain, bone marrow, umbilical cord, and adipose tissue. This review presents an overview of preclinical and clinical studies on cell therapy for stroke. We emphasize the current, limited knowledge about the biology of implant sources and discuss special conditions in stroke that will impact the potential success of neurotransplantation in clinical trials.
Collapse
Affiliation(s)
- Sean I Savitz
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
| | | | | | | | | |
Collapse
|
47
|
Giorgi FS, Malhotra S, Hasson H, Velísková J, Rosenbaum DM, Moshé SL. Effects of Status Epilepticus Early in Life on Susceptibility to Ischemic Injury in Adulthood. Epilepsia 2005; 46:490-8. [PMID: 15816942 DOI: 10.1111/j.0013-9580.2005.42304.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE Status epilepticus (SE) commonly occurs in children, whereas ischemic stroke is the most frequent neurologic insult in adults. The purpose of this study was to determine the effect of SE induced in immature (15 days old; PN15) male rats, on susceptibility to subsequent transient focal cerebral ischemia induced in adulthood. METHODS SE was induced by flurothyl ether (FE) or kainic acid (KA). Rats that did not develop seizures after FE or KA served as controls. Five weeks later, the now-adult rats were subjected to middle cerebral artery occlusion (MCAo) for 1 or 2 h by using the intraluminal filament technique. The extent of the infarct volume was evaluated 24 h later. RESULTS In rats submitted to 1-h-long FE-SE, the volume of infarction was significantly reduced compared with that in rats exposed to FE without SE. Longer duration of FE-SE was acutely lethal. KA-SE induced prolonged behavioral SE (156 +/- 17.5 min). In these rats, the volume of infarction was significantly larger compared with that in rats that did not show any electrographic seizures after KA administration. Comparison of FE and KA groups revealed that differences in the size of infarction were confined into cortical areas served by the MCA. Neither type of SE induced any obvious histologic changes in these neocortical regions before stroke induction. CONCLUSIONS Early in life, SE can influence the outcome of a subsequent focal ischemic insult in adulthood. The extent of the infarct is related to the duration and cause of SE. Prolonged SE induced by KA worsens the outcome, whereas FE-SE has a neuroprotective effect.
Collapse
Affiliation(s)
- Filippo S Giorgi
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, USA.
| | | | | | | | | | | |
Collapse
|
48
|
Abstract
Erythropoietin (EPO) has been viewed traditionally as a hematopoietic cytokine. Emerging evidence now exists supporting a physiologic role for EPO within the nervous system. EPO is expressed in the developing central nervous system and is capable of regulating the production of neuronal progenitor cells. There are numerous preclinical studies demonstrating a neuroprotective potential for EPO in a variety of disorders of both the central and peripheral nervous systems. A small pilot study in patients with acute ischemic stroke has recently been completed and the results are encouraging. Its mechanism of action is multifactorial but probably related to its ability to act as an antiapoptotic agent. Its widespread use clinically for the treatment of anemias has given us the experience and knowledge of its safety and pharmacokinetics. EPO is thus an ideal compound to study for the potential treatment of a variety of neurologic disorders.
Collapse
Affiliation(s)
- Samit Malhotra
- Department of Neurology, Albert Einstein College of Medicine, 1410 Pelham Parkway South, KC-303, Bronx, NY 10461, USA.
| | | | | |
Collapse
|
49
|
Abstract
On the basis of the distance-dependence of DNA-templated reductive amination reactions and of recent findings of D. Lynn and co-workers, we developed DNA-templated polymerizations of synthetic peptide nucleic acid (PNA) aldehydes. The coupling reactions proceed in a highly efficient and sequence-specific manner, even in the presence of mixtures of PNA aldehydes of different sequence. Synthetic peptide nucleic acid polymers containing as many as 40 PNA units (representing 10 consecutive coupling reactions) were formed efficiently. The ease of preparing PNAs containing tailor-made functional groups together with these findings raises the possibility of evolving synthetic sequence-defined polymers by iterated cycles of translation, selection, PCR amplification, and diversification previously available only to biological macromolecules.
Collapse
Affiliation(s)
- Daniel M Rosenbaum
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | | |
Collapse
|
50
|
Abstract
Cell transplantation is an experimental approach to restore brain function in neurodegenerative disorders such as Parkinson's and Huntington's disease. Transplantation also represents a possible strategy to repair the brain after a stroke. Various cell types are under investigation in experimental stroke studies. This review discusses the different graft sources and presents preliminary data on the transplantation of neural progenitor cells after stroke in rats. Following transplantation, progenitor cells proliferated and differentiated into all the different brain cell types, including neurons, and they repopulated the ischemic infarct. These results suggest that cell transplantation may serve as a future restorative therapy for stroke and other neurologic disorders such as Parkinson's disease, Alzheimer's disease, trauma, and multiple sclerosis.
Collapse
Affiliation(s)
- Sean L Savitz
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | | | | | | |
Collapse
|