AGE

, Volume 35, Issue 5, pp 1881–1897

Neuronal overexpression of insulin receptor substrate 2 leads to increased fat mass, insulin resistance, and glucose intolerance during aging

  • J. Zemva
  • M. Udelhoven
  • L. Moll
  • S. Freude
  • O. Stöhr
  • H. S. Brönneke
  • R. B. Drake
  • W. Krone
  • M. Schubert
Article

DOI: 10.1007/s11357-012-9491-x

Cite this article as:
Zemva, J., Udelhoven, M., Moll, L. et al. AGE (2013) 35: 1881. doi:10.1007/s11357-012-9491-x

Abstract

The insulin receptor substrates (IRS) are adapter proteins mediating insulin's and IGF1's intracellular effects. Recent data suggest that IRS2 in the central nervous system (CNS) is involved in regulating fuel metabolism as well as memory formation. The present study aims to specifically define the role of chronically increased IRS2-mediated signal transduction in the CNS. We generated transgenic mice overexpressing IRS2 specifically in neurons (nIRS2tg) and analyzed these in respect to energy metabolism, learning, and memory. Western blot (WB) analysis of nIRS2tg brain lysates revealed increased IRS2 downstream signaling. Histopathological investigation of nIRS2tg mice proved unaltered brain development and structure. Interestingly, nIRS2tg mice showed decreased voluntary locomotoric activity during dark phase accompanied with decreased energy expenditure (EE) leading to increased fat mass. Accordingly, nIRS2tg mice develop insulin resistance and glucose intolerance during aging. Exploratory behavior, motor function as well as food and water intake were unchanged in nIRS2tg mice. Surprisingly, increased IRS2-mediated signals did not change spatial working memory in the T-maze task. Since FoxO1 is a key mediator of IRS2-transmitted signals, we additionally generated mice expressing a dominant negative mutant of FoxO1 (FoxO1DN) specifically in neurons. This mutant mimics the effect of increased IRS2 signaling on FoxO-mediated transcription. Interestingly, the phenotype observed in nIRS2tg mice was not present in FoxO1DN mice. Therefore, increased neuronal IRS2 signaling causes decreased locomotoric activity in the presence of unaltered exploratory behavior and motor coordination that might lead to increased fat mass, insulin resistance, and glucose intolerance during aging independent of FoxO1-mediated transcription.

Keywords

IRS2BrainMiceInsulin resistanceDiabetesLocomotoric activity

Supplementary material

11357_2012_9491_Fig10_ESM.jpg (42 kb)
Suppl. Fig. 1

Phenotype of WT, nIRS2tg and homozygous (homo) nIRS2tg mice at the age of 60 weeks. Transgenic mice appear to have increased abdominal fat mass during aging. The phenotype was more pronounced in homozygous compared to heterozygous mice (JPEG 41 kb)

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11357_2012_9491_Fig11_ESM.jpg (45 kb)
Suppl. Fig. 2

Exploratory behavior and motor coordination of male nIRS2tg mice and respective controls. a Open field test. b Elevated O-Maze test. c Rotarod test, accel: latency to fall [s] at constantly increasing rounds per minute (rpm). Data are expressed as means ± SEM, n = 6 per group, *p < 0.05 (Student's t test), age: 40 weeks (JPEG 45 kb)

11357_2012_9491_MOESM2_ESM.tif (729 kb)
High Resolution Image(TIFF 728 kb)
11357_2012_9491_Fig12_ESM.jpg (7 kb)
Suppl. Fig. 3

Spatial memory and hippocampal function of male nIRS2tg mice and respective controls. a Enclosed T-maze test. Data represent means ± SEM, n = 6 per group, *p < 0.05 (Student's t test), age: 20 and 100 weeks (JPEG 7 kb)

11357_2012_9491_MOESM3_ESM.tif (131 kb)
High Resolution Image(TIFF 130 kb)

Copyright information

© American Aging Association 2012

Authors and Affiliations

  • J. Zemva
    • 1
    • 2
  • M. Udelhoven
    • 1
    • 2
  • L. Moll
    • 1
    • 2
    • 4
  • S. Freude
    • 1
    • 2
  • O. Stöhr
    • 1
    • 2
  • H. S. Brönneke
    • 3
  • R. B. Drake
    • 1
    • 2
  • W. Krone
    • 1
    • 2
    • 3
  • M. Schubert
    • 1
    • 2
    • 3
  1. 1.Center for Endocrinology, Diabetes and Preventive Medicine (CEDP)University of CologneCologneGermany
  2. 2.Center for Molecular Medicine Cologne (CMMC)University of CologneCologneGermany
  3. 3.Cologne Cluster of Excellence in Cellular Stress Responses in Aging-associated Diseases (CECAD)University of CologneCologneGermany
  4. 4.Biochemistry and Molecular Biology, Institute for Molecular Research Israel—Canada (IMRIC)School of Medicine of the Hebrew University of JerusalemJerusalemIsrael