1. Nicotinamide phosphoribosyl transferase in mammary gland epithelial cells is required for nicotinamide mononucleotide production in mouse milk.
- Author
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Hattori K, Kobayashi K, Azuma-Suzuki R, Iwasa K, Higashi S, Hamaguchi T, Saito Y, Morifuji M, and Nabeshima YI
- Subjects
- Animals, Female, Mice, Cytokines metabolism, NAD metabolism, Mice, Inbred C57BL, Nicotinamide Phosphoribosyltransferase metabolism, Nicotinamide Phosphoribosyltransferase genetics, Nicotinamide Mononucleotide metabolism, Mammary Glands, Animal metabolism, Mice, Knockout, Epithelial Cells metabolism, Milk metabolism, Lactation metabolism
- Abstract
Tissue-specific deficiency of nicotinamide phosphoribosyl transferase (NAMPT), the rate-limiting enzyme of the nicotinamide adenine dinucleotide (NAD
+ )-salvage pathway, causes a decrease of NAD+ in the tissue, resulting in functional abnormalities. The NAD+ -salvage pathway is drastically activated in the mammary gland during lactation, but the significance of this has not been established. To investigate the impact of NAD+ perturbation in the mammary gland, we generated two new lines of mammary gland epithelial-cell-specific Nampt-knockout mice (MGKO). LC-MS/MS analyses confirmed that the levels of NAD+ and its precursor nicotinamide mononucleotide (NMN) were significantly increased in lactating mammary glands. We found that murine milk contained a remarkably high level of NMN. MGKO exhibited a significant decrease in tissue NAD+ and milk NMN levels in the mammary gland during lactation periods. Despite the decline in NAD+ levels, the mammary glands of MGKO appeared to develop normally. Transcriptome analysis revealed that the gene profiles of MGKO were indistinguishable from those of their wild-type counterparts, except for Nampt. Although the NMN levels in milk from MGKO were decreased, the metabolomic profile of milk was otherwise unaltered. The mammary gland also contains adipocytes, but adipocyte-specific deficiency of Nampt did not affect mammary gland NAD+ metabolism or mammary gland development. These results demonstrate that the NAD+ -salvage pathway is activated in mammary epithelial cells during lactation and suggest that this activation is required for production of milk NMN rather than mammary gland development. Our MGKO mice could be a suitable model for exploring the potential roles of NMN in milk., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Yo-ichi Nabeshima reports financial support was provided by Meiji Holdings Co Ltd. Kouya Hattori, Rika Azuma-Suzuki, Seiichiro Higashi, Takashige Hamaguchi, Yoshie Saito, Masashi Morifuji reports a relationship with Meiji Holdings Co Ltd that includes: employment. The Department of Aging Science and Medicine is endowed by Meiji Holdings Co., Ltd. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
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