Unexpected effects of the MIP-CreER transgene and tamoxifen on β-cell growth in C57Bl6/J male mice.
Transgenic mouse models have been fundamental in the discovery of factors that regulate β-cell development, mass, and function. Several groups have recently shown that some of these models display previously uncharacterized phenotypes due to the transgenic system itself. These include impaired islet function and increased β-cell mass due to the presence of a human growth hormone (hGH) minigene as well as impaired β-cell proliferation in response to tamoxifen (TM) administration. We aimed to determine how these systems impact β-cell mass and proliferation during high fat diet (HFD). To this end, we utilized C57Bl6/J male MIP-CreERmice, which are known to express hGH, or wild-type (WT) mice treated with vehicle corn oil or TM In the absence of TM, MIP-CreERmice fed a chow diet have increased β-cell mass due to hypertrophy, whereas replication is unchanged. Similarly, after 1 week on HFD, MIP-CreERmice have increased β-cell mass compared to WT, and this is due to hypertrophy rather than increased proliferation. To assess the impact of TM on β-cell proliferation and mass, WT mice were treated with vehicle corn oil or TM and then fed a chow diet or HFD for 3 days. We observed that TM-treated mice have improved glucose homeostasis on chow diet but impaired β-cell proliferation in response to 3 days HFD feeding. These results unveil additional complications associated with commonly used pancreas-specific mouse models.
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee.
Bethany A
BA
Carboneau
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.
Thao D V
TD
Le
Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
Jennifer C
JC
Dunn
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, Tennessee Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee maureen.gannon@vanderbilt.edu.
Maureen
M
Gannon
Human growth hormone; tamoxifen; β‐cell mass; β‐cell proliferation
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