AI Article Synopsis

  • Cold exposure activates sympathetic nerves that increase fat cell (adipocyte) thermogenesis through a protein called uncoupling protein 1 (UCP1), which varies by sex and fat location.
  • Mammary gland duct cells in female mice influence UCP1 expression in subcutaneous white adipose tissue (scWAT) by releasing factors called 'mammokines.'
  • Research shows that these mammokines, particularly lipocalin 2, can limit UCP1 expression, resulting in lower fat oxidation and energy expenditure in females compared to males, highlighting sex-specific differences in fat metabolism.

Article Abstract

Sympathetic activation during cold exposure increases adipocyte thermogenesis via the expression of mitochondrial protein uncoupling protein 1 (UCP1). The propensity of adipocytes to express UCP1 is under a critical influence of the adipose microenvironment and varies between sexes and among various fat depots. Here we report that mammary gland ductal epithelial cells in the adipose niche regulate cold-induced adipocyte UCP1 expression in female mouse subcutaneous white adipose tissue (scWAT). Single-cell RNA sequencing shows that glandular luminal epithelium subtypes express transcripts that encode secretory factors controlling adipocyte UCP1 expression under cold conditions. We term these luminal epithelium secretory factors 'mammokines'. Using 3D visualization of whole-tissue immunofluorescence, we reveal sympathetic nerve-ductal contact points. We show that mammary ducts activated by sympathetic nerves limit adipocyte UCP1 expression via the mammokine lipocalin 2. In vivo and ex vivo ablation of mammary duct epithelium enhance the cold-induced adipocyte thermogenic gene programme in scWAT. Since the mammary duct network extends throughout most of the scWAT in female mice, females show markedly less scWAT UCP1 expression, fat oxidation, energy expenditure and subcutaneous fat mass loss compared with male mice, implicating sex-specific roles of mammokines in adipose thermogenesis. These results reveal a role of sympathetic nerve-activated glandular epithelium in adipocyte UCP1 expression and suggest that mammary duct luminal epithelium has an important role in controlling glandular adiposity.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10529063PMC
http://dx.doi.org/10.1038/s41586-023-06361-5DOI Listing

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