Matias, C. V. | bioRxiv Science

bioRxiv2025

Depot-Specific Roles for C/EBPα in White Adipose Tissue Development and Metabolism

Rates of obesity and its associated metabolic comorbidities continue to rise in the developed world. It is well established that in obesity, the distribution and not just amount of excess white adipose tissue (WAT) correlates with a persons risk for comorbidities such as coronary artery disease and type 2 diabetes. Thus, understanding the specific mechanisms that drive WAT development in specific adipose depots could elucidate novel mechanisms of metabolic disease. SNPs near the gene CEBPA have been associated with multiple cardiometabolic traits by human genome-wide association studies, including waist-to-hip ratio, suggesting that CEBPA regulates WAT distribution. CEBPA encodes a well characterized transcription factor (C/EBP) that is long recognized as a master regulator of adipocyte differentiation, yet depot-specific roles for C/EBP have not been previously described. To further investigate this genetic link, we generated mice with adipocyte-specific Cebpa knockout (Cebpa_ASKO) and found that these mice are almost entirely lacking gonadal WAT (gWAT) despite the inguinal WAT (iWAT) being present in near normal amounts. Despite developing, Cebpa_ASKO iWAT contains fewer and larger adipocytes, and fails to expand when challenged with high fat diet. RNA-seq and functional studies demonstrate evidence of altered lipid metabolism and adipocyte function in Cebpa_ASKO iWAT. Finally, Cebpa_ASKO mice have multiple other metabolic phenotypes, including lipid-laden BAT, increased hepatic triglycerides, and increased plasma cholesterol, all of which worsen with prolonged high fat diet feeding. Taken together, these data highlight depot-specific roles for C/EBP in adipose tissue development, as well as the importance of adipocyte C/EBP in maintaining metabolic homeostasis.

physiology↗

bioRxiv2024

ADAMTS7 Promotes Smooth Muscle Cell Foam Cell Expansion in Atherosclerosis

Human genetic studies have repeatedly associated ADAMTS7 with atherosclerotic cardiovascular disease. Subsequent investigations in mice demonstrated that ADAMTS7 is proatherogenic and induced in response to vascular injury. However, the cell-specific mechanisms governing ADAMTS7 proatherogenicity remain unclear. To determine which vascular cell types express ADAMTS7, we interrogated single-cell RNA sequencing of human carotid atherosclerosis and found ADAMTS7 expression in smooth muscle cells (SMCs), endothelial cells (ECs), and fibroblasts. We subsequently created SMC- and EC-specific Adamts7 conditional knockout and transgenic mice. Conditional knockout of Adamts7 in either cell type does not reduce atherosclerosis, whereas transgenic induction in either cell type increases atherosclerosis. In SMC transgenic mice, this increase coincides with an expansion of lipid-laden SMC foam cells and a decrease in fibrous cap formation. RNA-sequencing in Adamts7 overexpressing SMCs revealed an upregulation of lipid genes typically assigned to macrophages. Mechanistically, ADAMTS7 increases SMC oxLDL uptake through CD36, whose expression is upregulated by PU.1. ATAC-seq and motif analysis revealed increased chromatin accessibility at AP-1 enriched regions, consistent with AP-1 dependent remodeling of PU.1-regulated lipid-handling loci. In summary, ADAMTS7 promotes atherosclerosis by driving SMC foam cell formation through an AP-1/PU.1/CD36 regulatory axis.

pathology↗