© 2000 by The Society for Integrative and Comparative Biology
A Tribute to Erika M. Plisetskaya: New Insights on the Function and Evolution of Gastroenteropancreatic Hormones. Introduction to the Symposium1
1 Department of Zoology and Regulatory Biosciences Center, North Dakota State University, Fargo, North Dakota 58105
2 Department of Biochemistry and Molecular Biology, University of New Hampshire, Durham, New Hampshire 03824
 |
INTRODUCTION |
|---|
TOP
 INTRODUCTION CONTRIBUTIONS OF ERIKA M....OVERVIEW OF THE SYMPOSIUMReferences |
|---|
Since the discovery of the first hormone, secretin, from the gastrointestinal tract by Bayliss and Starling in 1902
, our knowledge of chemical mediators produced by the gastroenteropancreatic (GEP) system has grown considerably. The emergence of each new experimental approach ushered in a wave of new information. The latest developments in molecular biological approaches have and will continue to provide many important insights into hormone biology. Today, we know that the GEP cell feature of amine precursor uptake and decarboxylation (APUD) is shared by many other cell types (Norris, 1997); in fact, hormones secreted by the GEP also are secreted by cells of the nervous system, leading to the notion of a "brain-gut" distribution of hormones that makes the distinction between the endocrine system and nervous system no longer tenable (Thorndyke and Falkmer, 1985). We also now know that many GEP/neural hormones exist in a variety of molecular forms, sometimes co-localized with other factors, that modulate a vast array of functions in target cells that may be either distant or near to the site of secretion (see Holmgren, 1989). It is indeed interesting that the GEP system, the system that gave us the term "hormone" (Starling, 1905), now forces us to re-examine what a hormone is. This symposium was designed to advance such a re-examination by bringing together GEP researchers whose recent work has provided new information on several critical issues that face hormone biology; among this information includes insights into the following topics: 1) origins of hormones, 2) hormone biosynthesis—from gene to bioactive peptide, 3) hormone structure-function relationships, and 4) ligand-receptor interactions. The comparative approaches employed by the participants uniquely posture this symposium to provide an integrated, up-to-date view about the evolution of the GEP system in animals.
|
CONTRIBUTIONS OF ERIKA M. PLISETSKAYA TO THE FIELD OF GASTROENTEROPANCREATIC PHYSIOLOGY |
|---|
|
TOP
INTRODUCTIONCONTRIBUTIONS OF ERIKA M....OVERVIEW OF THE SYMPOSIUMReferences |
|---|
This symposium was held in honor of Dr. Erika M. Plisetskaya. Dr. Plisetskaya's research, recounted in over 160 papers, laid the framework for much of our current understanding about the evolution of GEP hormones and of metabolic/growth control systems. Dr. Plisetskaya's scientific career has spanned over 40 years. The first twenty-five of these years she spent as a scientist working in the Soviet Union of Socialist Republics. In 1979, she immigrated to the United States. During her career, she had the opportunity of collaborating and interacting with two outstanding comparative endocrinologists, Dr. Leo Leibson in Russia and Dr. Aubrey Gorbman in the United States. During the past seventeen years while in the USA, Dr. Plisetskaya's research activity has nearly doubled (Fig. 1).
|
Dr. Plisetskaya has made significant contributions to our understanding of the GEP system through the use of comparative and integrative approaches. These contributions occurred, in part, because she focused on evolutionarily important groups of animals that had either not been studied or studied very little in respect to the metabolic role of pancreatic hormones belonging to insulin, glucagon, somatostatin and pancreatic peptide superfamilies. Her experimental models have included bivalve molluscs, slugs, lancelet, hagfish, lampreys, numerous groups of teleost fish, including scorpion fish, several species of salmonids and catfish, frogs, turtles, chicken, and mammals (rats). As examples, she worked on lampreys in the early sixties, molluscs and lancelet in the early seventies, and teleosts in the early eighties.
Therefore, Dr. Plisetskaya and the field of GEP hormones evolved, grew and expanded together. In 1975, she published a book entitled, Hormonal Regulation of Carbohydrate Metabolism in Lower Vertebrates, which thoroughly covered the field from its very beginning and for the next 50 years. Times have changed, and the field of GEP hormones and peptides has exploded. Dr. Plisetskaya feels that she would not be able to cover the same field for the last 25 years in a single book because of all the new knowledge that has become available (see the Sower et al. paper from this symposium). She has tried to compensate and has written more narrowly focused reviews. As an example, one of her most memorable recent reviews in this field was entitled "Glucagon and Glucagon-like peptides in Fishes" (Plisetskaya and Mommsen, 1996).
Dr. Plisetskaya has always been very much interested in hormonal regulation of metabolism and mechanisms of hormonal action. She prides herself not with her own significant achievements, but on being a catalyst for creating networks of scientists in the field, mostly including younger scientists. With the invaluable help of Dr. J. R. Kimmel and H. G. Pollack, in 1984–1986, she was the first to isolate and sequence six major pancreatic hormones of salmon and three major islet hormones from lamprey. Antisera have been raised against each of these peptides and species-specific RIAs established and validated. During a very short time period, from 1990 to 1995, her antisera were requested and made available for radioimmunoassays as well as immunocytochemical, physiological and metabolic studies conducted by 35 research groups around the world, including groups from the U.S., Canada, Japan and in some 10 European Countries—the United Kingdom, Spain, Portugal, Netherlands, Switzerland, Germany, Belgium, Norway, Italy and France. Moreover, responding to requests, her laboratory assayed pancreatic hormones in fish plasma samples for 17 research projects in the U.S., Canada, Russia, Brazil and four European countries—Germany, France, Norway and Sweden. Many of her collaborations have lasted for many years, and a number of them are still active and continue to develop as is evident from this Symposium.
Dr. Plisetskaya's scientific accomplishments and contributions have world-wide acclaim. It has been a great honor and privilege for each of us to have known her as a friend and a valued colleague and collaborator.
|
OVERVIEW OF THE SYMPOSIUM |
|---|
|
TOP
INTRODUCTIONCONTRIBUTIONS OF ERIKA M....OVERVIEW OF THE SYMPOSIUMReferences |
|---|
The constraints of a single-day symposium necessarily limited the number of papers. In the end, we choose to include topics that represented the full breadth of research interests of the honoree, Dr. Erika M. Plisetskaya. Collated in this symposium are reviews concerning the signaling systems of insulin/insulin-like growth factors, glucagon/glucagon-like peptides, somatostatins, gastrin/cholecystokinin (CCK), neuropeptide Y (NPY), and several other GEP factors. Information is provided about the structure, function, and evolution of the hormones themselves as well as of their cognate receptors.
The first paper by Sower et al. provides a perspective on research of GEP hormones in invertebrates and vertebrates by examining publication trends between 1980 and 1997. The next paper by Youson traces the study of the enteropancreatic system in the earliest extant vertebrates, the agnathans (hagfish and lamprey). Emphasis is placed on the nature and development of the agnathan endocrine pancreas as well as on differences in the distribution of cell types and in the primary structure of peptides produced in agnathan pancreata.
The following four papers summarize the current understanding about the evolution and function of the insulin/insulin-like growth factor (IGF) family of peptides. The paper by Conlon provides an updated view of the molecular evolution of insulins. He advances the notion that the conformation of insulin in the crystal structure is an inactive one and that specific epitopes are important for maintaining the receptor-binding conformation—a notion that is supported by the observed conservation of critical amino acids among the primary structures of insulins of a wide array of vertebrates, from hagfish to birds. The paper by Chan and Steiner reviews the structure and function of the insulin/IGF family in vertebrates and invertebrates. Studies to date suggest that insulin-like peptides in invertebrates function primarily as mitogenic agents which promote tissue growth and development; whereas, in vertebrates, the mitogenic action has been subsumed by IGF-I and IGF-II, while insulin acquired a metabolic regulatory role. The paper by Planas et al. reviews the structural and functional characteristics of insulin and IGF receptors. Although all gnathostomes, from fish to mammals, possess specific receptors for insulin and IGF-I, qualitative differences in functional aspects of these receptors can account for variations in the biological activity of insulin and IGF-I. The paper by Wright et al. reveals how the anatomically discrete islet organ of certain teleost fish, called the Brockmann body, can be used as a model system to study various aspect of islet function, including regulation of insulin gene expression.
The paper by Mojsov points out that glucagon-like peptide-1 (GLP-1) stimulates insulin release and inhibits nutrient absorption in mammals, but increases glucose levels in fish by activating glycogenolysis and gluconeogenesis. The basis of the differences in glucose homeostatic mechanisms between mammals and fish may lie, at least in part, with differences in the GLP-1 receptor. The paper by Mommsen examines further the disparate actions of GLP-1 in fish and mammals and raises the possibility that differences in the transduction components of the signaling systems also may be important to understanding the functional disparity. For example, in mammalian ß-cells, GLP-1 receptors activate the adenylyl cyclase/cAMP system, while in fish hepatocytes, a primary target of GLP-1 action, adenylyl cyclase/cAMP plays a subordinate role.
Somatostatins, gastrin/CCK, and NPY are discussed in the last three papers. The paper by Sheridan et al. reviews the multi-functional nature of the somatostatin family. The multiple actions arise from an elaborate, multi-faceted signaling system consisting of numerous somatostatin signaling molecules, several receptors subtypes, and a wide array of cellular effector pathways. The paper by Vigna discusses the structure, function, and evolution of gastrin and CCK and the structure and evolution of their receptors. Current evidence suggests that CCK evolved early in chordate evolution and that gastrin-like peptides arose from an ancestral CCK about the time that tetrapods diverged from fish. The paper by Silverstein and Plisetskaya examines the role of NPY on the regulation of food intake. NPY expression increases in fasting salmon in concert with decreasing plasma insulin levels. Intracerebroventricular injection of NPY into catfish directly stimulates food intake.
|
ACKNOWLEDGMENTS |
|---|
The organizers are grateful to our home institutions for the support we received for the organization of this symposium. In particular, the assistance of Sheila Kath and Trisha Tank at NDSU was invaluable during all stages of the project. We also would like to thank The Society for Integrative and Comparative Biology (SICB) for extending staff and financial support to our effort. The symposium was sponsored by The US National Committee for The International Union of Biological Sciences as well as by the Divisions of Comparative Endocrinology and Comparative Physiology and Biochemistry, SICB. A special acknowledgment also goes to Merck Research Laboratories and to NSF (IBN 9809909), the financial support of which made this symposium a reality.
|
FOOTNOTES |
|---|
1 From the symposium A Tribute to Erika M. Plisetskaya: New Insights on the Function and Evolution of Gastroenteropancreatic Hormones presented at the Annual Meeting of the Society for Integrative and Comparative Biology, 6–10 January 1999, at Denver, Colorado.
2 E-mail: msherida{at}plains.nodak.edu
3 E-mail: sasower{at}christa.unh.edu
|
REFERENCES |
|---|
|
TOP
INTRODUCTIONCONTRIBUTIONS OF ERIKA M....OVERVIEW OF THE SYMPOSIUMReferences |
|---|
Bayliss, W.M., and E.H. Starling. 1902. Mechanisms of pancreatic secretion. J. Physiol., 28:325-353.
Holmgren, S. 1989. The comparative physiology of regulatory peptides.. Chapman and Hall., London/New York.
Norris, D.O. 1997. Vertebrate endocrinology. 3rd ed. Academic Press, New York.
Plisetskaya, E.M., and T.P. Mommsen. 1996. Glucagon and glucagon-like peptide in fishes. In K.W. Jeon (ed.)International review of cytology, Vol. 168, A survey of cell biology, pp. 187-257.
Starling, E.H. 1905. The chemical correlation of the functions of the body. Lancet, 1:340-341.
Thorndyke, M.C., and S. Falkmer. 1985. Evolution of the gastro-entero-pancreatic endocrine systems in lower vertebrates. In R.E. Foreman, A. Gorbman, J.M. Dodd, R. Olson (eds.)Evolutionary biology of primitive fishes, pp. 379-400Plenum Press, New York.
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||