Mol Metab.: co-auth.: B. Thorens

Mol Metab. 2021 Jul 26;101311. doi: 10.1016/j.molmet.2021.101311. Online ahead of print.

Ablation of glucokinase-expressing tanycytes impacts energy balance and increases adiposity in mice

Antoine Rohrbach 1Emilie Caron 2Rafik Dali 3Maxime Brunner 4Roxane Pasquettaz 5Irina Kolotuev 6Federico Santoni 4Bernard Thorens 5Fanny Langlet 7


Objectives: Glucokinase (GCK) is critical for glucosensing. In rats, GCK is expressed in hypothalamic tanycytes and appears to play an essential role in feeding behavior. In this study, we investigated the distribution of GCK-expressing tanycytes in mice and their role in the regulation of energy balance.

Methods: In situ hybridization, reporter gene assay, and immunohistochemistry were used to assess GCK expression along the third ventricle in mice. To evaluate the impact of GCK-expressing tanycytes on arcuate neuron function and mouse physiology, Gck deletion along the ventricle was achieved using loxP/Cre recombinase technology in adult mice.

Results: GCK expression was low along the third ventricle but detectable in tanycytes facing the ventromedial arcuate nucleus from bregma -1.5 to -2.2. Gck deletion induced the death of this tanycyte subgroup through the activation of the BAD signaling pathway. The ablation of GCK-expressing tanycytes affected different aspects of energy balance, leading to an increase in adiposity in mice. This phenotype was systematically associated with a defect in NPY neuron function. In contrast, the regulation of glucose homeostasis was mostly preserved, except for glucoprivic responses.

Conclusions: This study describes an additional role for GCK in tanycyte biology and highlights the impact of tanycyte loss on the regulation of energy balance.

Keywords: Apoptosis; Energy Balance; Glucokinase; Glucose homeostasis; Hypothalamus; Tanycytes.