HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 286/3/R498    most recent 00509.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Hoehn, K. L. Articles by Florant, G. L. Search for Related Content PubMed PubMed Citation Articles by Hoehn, K. L. Articles by Florant, G. L.

APPETITE, OBESITY AND METABOLISM

Seasonal, tissue-specific regulation of Akt/protein kinase B and glycogen synthase in hibernators

Departments of ²Biology and of ¹Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870

Submitted 3 September 2003 ; accepted in final form 24 November 2003

Yellow-bellied marmots (Marmota flaviventris) exhibit a circannual cycle of hyperphagia and nutrient storage in the summer followed by hibernation in the winter. This annual cycle of body mass gain and loss is primarily due to large-scale accumulation of lipid in the summer, which is then mobilized and oxidized for energy during winter. The rapid and predictable change in body mass makes these animals ideal for studies investigating the molecular basis for body weight regulation. In the study described herein, we monitored seasonal changes in the protein levels and activity of a central regulator of anabolic metabolism, the serine-threonine kinase Akt-protein kinase B (Akt/PKB), during the months accompanying maximal weight gain and entry into hibernation (June-November). Interestingly, under fasting conditions, Akt/PKB demonstrated a tissue-specific seasonal activation. Specifically, although Akt/PKB levels did not change, the activity of Akt/PKB (isoforms 1/ and 2/) in white adipose tissue (WAT) increased significantly in July. Moreover, glycogen synthase, which lies downstream of Akt/PKB on a linear pathway linking the enzyme to the stimulation of glycogen synthesis, demonstrated a similar pattern of seasonal activation. By contrast, Akt/PKB activity in skeletal muscle peaked much later (i.e., September). These data suggest the existence of a novel, tissue-specific mechanism regulating Akt/PKB activation during periods of marked anabolism.

insulin; metabolism; hibernation

This article has been cited by other articles:

				Y. L. Ma, X. Zhu, P. M. Rivera, O. Toien, B. M. Barnes, J. C. LaManna, M. A. Smith, and K. L. Drew Absence of cellular stress in brain after hypoxia induced by arousal from hibernation in Arctic ground squirrels Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2005; 289(5): R1297 - R1306. [Abstract] [Full Text] [PDF]

				C. C. Fleck and H. V. Carey Modulation of apoptotic pathways in intestinal mucosa during hibernation Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2005; 289(2): R586 - R595. [Abstract] [Full Text] [PDF]