Gene pathway development in human epicardial adipose tissue during early life

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Abstract

Studies in rodents and newborn humans demonstrate the influence of brown adipose tissue (BAT) in temperature control and energy balance and a critical role in the regulation of body weight. Here, we obtained samples of epicardial adipose tissue (EAT) from neonates, infants, and children in order to evaluate changes in their transcriptional landscape by applying a systems biology approach. Surprisingly, these analyses revealed that the transition to infancy is a critical stage for changes in the morphology of EAT and is reflected in unique gene expression patterns of a substantial proportion of thermogenic gene transcripts (~10%). Our results also indicated that the pattern of gene expression represents a distinct developmental stage, even after the rebound in abundance of thermogenic genes in later childhood. Using weighted gene coexpression network analyses, we found precise anthropometric-specific correlations with changes in gene expression and the decline of thermogenic capacity within EAT. In addition, these results indicate a sequential order of transcriptional events affecting cellular pathways, which could potentially explain the variation in the amount, or activity, of BAT in adulthood. Together, these results provide a resource to elucidate gene regulatory mechanisms underlying the progressive development of BAT during early life.

Authors

Shalini Ojha, Hernan P. Fainberg, Victoria Wilson, Giuseppe Pelella, Marcos Castellanos, Sean T. May, Attilio A. Lotto, Harold Sacks, Michael E. Symonds, Helen Budge

Epidermal CYLD inactivation sensitizes mice to the development of sebaceous and basaloid skin tumors

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Abstract

The deubiquitinase-encoding gene Cyld displays a dominant genetic linkage to a wide spectrum of skin-appendage tumors, which could be collectively designated as CYLD mutant–syndrome (CYLD^m-syndrome). Despite recent advances, little is understood about the molecular mechanisms responsible for this painful and difficult-to-treat skin disease. Here, we generated a conditional mouse model with epidermis-targeted expression of a catalytically deficient CYLD^m through K14-Cre–mediated deletion of exon 9 (hereafter refer to Cyld^EΔ9/Δ9). Cyld^EΔ9/Δ9 mice were born alive but developed hair and sebaceous gland abnormalities and dental defects at 100% and 60% penetrance, respectively. Upon topical challenge with DMBA/TPA, these animals primarily developed sebaceous and basaloid tumors resembling human CYLD^m-syndrome as opposed to papilloma, which is most commonly induced in WT mice by this treatment. Molecular analysis revealed that TRAF6-K63-Ubiquitination (K63-Ub), c-Myc-K63-Ub, and phospho-c–Myc (S62) were markedly elevated in Cyld^EΔ9/Δ9 skin. Topical treatment with a pharmacological c-Myc inhibitor induced sebaceous and basal cell apoptosis in Cyld^EΔ9/Δ9 skin. Consistently, c-Myc activation was readily detected in human cylindroma and sebaceous adenoma. Taken together, our findings demonstrate that Cyld^EΔ9/Δ9 mice represent a disease-relevant animal model and identify TRAF6 and c-Myc as potential therapeutic targets for CYLD^m-syndrome.

Authors

Yingai Jane Jin, Sally Wang, Joshua Cho, M. Angelica Selim, Tim Wright, George Mosialos, Jennifer Y. Zhang

Restoration of lymphatic function rescues obesity in Prox1-haploinsufficient mice

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Abstract

Prox1 heterozygous mice have a defective lymphatic vasculature and develop late-onset obesity. Chyle abnormally leaks from those vessels, accumulates in the surrounding tissues, and causes an increase in adipose tissue. We characterized the lymphatics of Prox1^+/– mice to determine whether the extent of obesity correlated with the severity of lymphatic defects. The lymphatic vasculature in Prox1^+/– mice exhibited reduced tracer clearance from the ear skin, dysfunctional perfusion of the lower legs, and reduced tracer uptake into the deep lymphatic collectors during mechanostimulation prior to the onset of obesity. Ear lymphatic vessels and leg collectors in Prox1^+/– mice were disorganized and irregular, further confirming that defective lymphatic vessels are associated with obesity in Prox1^+/– mice. We now provide conclusive in vivo evidence that demonstrates that leaky lymphatics mediate obesity in Prox1^+/– mice, as restoration of lymphatic vasculature function was sufficient to rescue the obesity features in Prox1^+/– mice. Finally, depth-lipomic profiling of lymph contents showed that free fatty acids induce adipogenesis in vitro.

Authors

Noelia Escobedo, Steven T. Proulx, Sinem Karaman, Miriam E. Dillard, Nicole Johnson, Michael Detmar, Guillermo Oliver