Molecular Cloning and Functional Characterization of Goldfish Alpha 2 Adrenergic Receptors

Molecular Cloning and Functional Characterization of Goldfish Alpha 2 Adrenergic Receptors

This dissertation, "Molecular Cloning and Functional Characterization of Goldfish Alpha-2 Adrenergic Receptors" by Hoi-yan, Chan, 陳凱恩, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to ...

Author: HOI-YAN. CHAN

Publisher:

ISBN: 1374724823

Category:

Page:

View: 568

This dissertation, "Molecular Cloning and Functional Characterization of Goldfish Alpha-2 Adrenergic Receptors" by Hoi-yan, Chan, 陳凱恩, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled MOLECULAR CLONING AND FUNCTIONAL CHARACTERIZATION OF GOLDFISH ALPHA-2 ADRENERGIC RECEPTORS Submitted by Chan Hoi Yan for the degree of Master of Philosophy at The University of Hong Kong in September 2004 In mammals, adrenergic stimulation at the hypothalamic level through alpha-2 adrenergic receptors can induce growth hormone secretion from the pituitary. However, the alpha-2 receptor subtype(s) responsible for this stimulatory action has not been elucidated. In the goldfish, we have previously shown that alpha-2 activation at the pituitary level can suppress growth hormone release and that removal of alpha-2 inhibition can trigger a rebound of growth hormone secretion. These findings have prompted us to speculate that alpha-2 adrenergic receptors should be expressed in goldfish pituitary cells and be responsible for the growth hormone regulation by adrenergic input at the pituitary level. As a first step to study the alpha-2 receptor subtype(s) expressed in the goldfish pituitary, molecular cloning was performed to establish the structural identity of the goldfish alpha-2A, alpha-2B, and alpha-2C adrenergic receptors. By library screening and 3'/5' RACE, the complementary DNAs (cDNAs) for alpha-2A, alpha-2B, and alpha-2C adrenergic receptors with the sizes of 2.72 Kb, 2.86 Kb, and 1.72 Kb, respectively, have been isolated from the brain-pituitary axis of the goldfish. The open-reading frames of these cDNAs encode proteins of 383 to 505 amino acids in size with seven transmembrane domains typical of those of the G protein-coupled receptors. Sequence analysis also reveals that these goldfish alpha-2A, alpha-2B, and alpha-2C adrenergic receptors are structurally homologous to the corresponding receptor subtypes in mammals. By reverse transcription polymerase chain reaction (RT-PCR), the transcripts of alpha-2A and alpha-2B adrenergic receptors were identified in many tissues in the goldfish, including the heart, liver, gill, intestine, kidney, muscle, spleen, pituitary, and various brain segments. A similar expression pattern was also noted for alpha-2C adrenergic receptor, except that its mRNA was not detected in the intestine and its expression in the brain was restricted to the brain stem and spinal cord. To characterize the pharmacological and biochemical properties of these newly cloned receptors, functional expression of goldfish alpha-2A, alpha-2B, and alpha-2C adrenergic receptors was conducted in Chinese hamster ovary (CHO) cells. In this case, the receptor binding properties of these goldfish adrenergic receptors were tested using a radioreceptor binding approach. Although the order of affinity of the respective alpha-2A, alpha-2B, and alpha-2C adrenergic receptors is different from that reported in mammals, these receptors consistently exhibited a high affinity for ligands selective for alpha-2 but not for alpha-1 and beta adrenergic receptors. Furthermore, activation of these receptors by norepinephrine or the alpha-2 agonist + + clonidine could trigger rapid activation of the Na /H exchanger, an inhibition of 2+ cyclic AMP production and a decrease in intracellular Ca levels. These results, taken together, have confirmed that these newly cloned receptors are functional alpha-2 adrenergic receptors in the goldfish. The cDNAs for the goldfish alpha-2A, alpha-2B, and alpha-2C
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The alpha 1 Adrenergic Receptors

The alpha 1 Adrenergic Receptors

This is evidenced by the fact that the alpha-l adrenergic receptor plays a prominent functional role in most organs of the body and in the key systems responsible for survival of the organism and maintenance of optimum biological activity.

Author: Jr. Ruffolo

Publisher: Springer Science & Business Media

ISBN: 9781461245827

Category: Medical

Page: 544

View: 179

During the past decade, great strides have been made in our un derstanding of the biochemistry and pharmacology of the alpha-l adrenergic receptor. The alpha-l adrenergic receptor plays a key role in biological function. This is evidenced by the fact that the alpha-l adrenergic receptor plays a prominent functional role in most organs of the body and in the key systems responsible for survival of the organism and maintenance of optimum biological activity. This is most apparent in the cardiovascular system, in which alpha-l adrenergic receptors are the single most important receptor involved in the maintenance of blood pressure and circu latory function. It is appropriate, therefore, that recent findings related to the pharmacology and biochemistry of the alpha-l adrenergic receptor be compiled, since this subject has not been reviewed in detail in recent years. It is the purpose of this book to present a series of reviews of key experimental findings that shed new light on the alpha-l adrenergic receptor and the manner in which it functions. Classically, most receptors have been characterized based on structure-activity relationships obtained for selective agonists and antagonists interacting with the receptor. Although there are many newer and more sophisticated approaches to receptor char acterization, structure-activity relationships still provide impor tant information regarding the chemical requirements made by the receptor for its occupation by ligands and its subsequent acti vation by those ligands possessing intrinsic efficacy and, there fore, agonist activity.
Categories: Medical

Alpha 2 adrenergic Receptors

Alpha 2 adrenergic Receptors

Author: Stephen M. Lanier

Publisher:

ISBN: OCLC:1193359286

Category: Alpha adrenoceptors

Page: 195

View: 668

Categories: Alpha adrenoceptors

Adrenergic alpha Receptors Advances in Research and Application 2012 Edition

Adrenergic alpha Receptors   Advances in Research and Application  2012 Edition

Adrenergic alpha Receptors—Advances in Research and Application: 2012 Edition is a ScholarlyPaper™ that delivers timely, authoritative, and intensively focused information about Adrenergic alpha Receptors in a compact format.

Author:

Publisher: ScholarlyEditions

ISBN: 9781481632676

Category: Medical

Page: 23

View: 708

Adrenergic alpha Receptors—Advances in Research and Application: 2012 Edition is a ScholarlyPaper™ that delivers timely, authoritative, and intensively focused information about Adrenergic alpha Receptors in a compact format. The editors have built Adrenergic alpha Receptors—Advances in Research and Application: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Adrenergic alpha Receptors in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Adrenergic alpha Receptors—Advances in Research and Application: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Categories: Medical