A UCP1-IRES-Cre knock-in mouse enables specific brown adipocyte targeting without CNS off-target expression

Uncoupling protein 1 (UCP1) is predominantly expressed in brown adipocytes and plays a central role in thermogenesis and energy metabolism. BAC-transgenic UCP1-Cre mouse lines have been widely used to target thermogenic adipocytes, but ectopic Cre activity in the hypothalamus and peripheral organs has raised concerns regarding specificity. Here, we characterize a novel knock-in UCP1-IRES-Cre mouse model that drives Cre expression from the endogenous UCP1 promoter.

UCP1-IRES-Cre mice were crossed with Ai14 reporter mice to visualize Cre-dependent tdTomato expression across adipose depots, brain regions, and peripheral tissues and compared with UCP1 protein localization. Reporter expression in male and female UCP1-IRES-Cre mice closely mirrored endogenous UCP1 expression in brown and white adipose tissue depots, with substantially reduced ectopic activity compared with previously reported BAC-transgenic models. Very limited reporter signal was observed in the hypothalamus and peripheral organs, although robust reporter expression was detected in the choroid plexus despite absent UCP1 protein staining.

Surface image analysis in various adipose depots demonstrated generally broader reporter labeling than UCP1 immunoreactivity, consistent with transient or prior UCP1 promoter activation during development or adult life. Together, these findings demonstrate that the UCP1-IRES-Cre model faithfully recapitulates endogenous UCP1 expression while minimizing off-target Cre activity and provides a knock-in alternative for genetic targeting of thermogenic adipocytes. This work was in part supported by grants from the National Institutes of Health (2R01 DK092587-06, 4OT2 OD23864-01) to HM and R01 DK134469 to CME.

Joshua Meyer and Jaclyn Williams contributed equally to this work. Neurobiology of Nutrition & Metabolism, Pennington Biomedical Research Center, 70808, Baton Rouge, LA, USA Joshua Meyer, Jaclyn Williams & Heike Münzberg Matrix Biology Laboratory, Pennington Biomedical Research Center, 70808, Baton Rouge, LA, USA Gene Regulation and Metabolism Laboratory, Pennington Biomedical Research Center, 70808, Baton Rouge, LA, USA Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA, 70808, USA The authors declare no competing interests. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Below is the link to the electronic supplementary material. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.