Brown adipose tissue (BAT) is highly metabolically active tissue that dissipates energy via UCP1 as heat, and BAT mass is correlated negatively with obesity. The presence of BAT/BAT-like tissue in humans renders BAT as an attractive target against obesity and insulin resistance. Here, we identify Aifm2, a NADH oxidoreductase domain containing flavoprotein, as a lipid droplet (LD)-associated protein highly enriched in BAT. Aifm2 is induced by cold as well as by diet. Upon cold or b-adrenergic stimulation, Aifm2 associates with the outer side of the mitochondrial inner membrane. As a unique BAT-specific first mammalian NDE (external NADH dehydrogenase)like enzyme, Aifm2 oxidizes NADH to maintain high cytosolic NAD levels in supporting robust glycolysis and to transfer electrons to the electron transport chain (ETC) for fueling thermogenesis. Aifm2 in BAT and subcutaneous white adipose tissue (WAT) promotes oxygen consumption, uncoupled respiration, and heat production during cold-and diet-induced thermogenesis. Aifm2, thus, can ameliorate dietinduced obesity and insulin resistance.

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Brain and Reproductive Organ Expressed (BRE), or BRCC45, is a death receptor-associated antiapoptotic protein, which is also involved in DNA-damage repair, and K63-specific deubiquitination. BRE overexpression attenuates both death receptor- and stress-induced apoptosis, promotes experimental tumor growth, and is associated with human hepatocellular and esophageal carcinoma. How BRE mediates its antiapoptotic function is unknown. Here we report based on the use of a mouse Lewis lung carcinoma cell line D122 that BRE has an essential role in maintaining the cellular protein level of XIAP, which is the most potent endogenous inhibitor of the caspases functioning in both extrinsic and intrinsic apoptosis. shRNA-mediated exhaustive depletion of BRE sensitized D122 cells to apoptosis induced not only by etopoxide, but also by TNF-α even in the absence of cycloheximide, which blocks the synthesis of antiapoptotic proteins by TNF-α-activated NF-κB pathway. In BRE-depleted cells, protein level of XIAP was downregulated, but not the levels of other antiapoptotic proteins, cIAP-1, 2, and cFLIP, regulated by the same NF-κB pathway. Reconstitution of BRE restored XIAP levels and increased resistance to apoptosis. XIAP mRNA level was also reduced in the BRE-depleted cells, but the level of reduction was less profound than that of the protein level. However, BRE could not delay protein turnover of XIAP. Depletion of BRE also increased tumor cell apoptosis, and decreased both local and metastatic tumor growth. Taken together, these findings indicate that BRE and its XIAP-sustaining mechanism could represent novel targets for anti-cancer therapy.

Brown adipose tissue is a metabolically beneficial organ capable of dissipating chemical energy into heat, thereby increasing energy expenditure. Here, we identify Dot1l, the only known H3K79 methyltransferase, as an interacting partner of Zc3h10 that transcriptionally activates the Ucp1 promoter and other BAT genes. Through a direct interaction, Dot1l is recruited by Zc3h10 to the promoter regions of thermogenic genes to function as a coactivator by methylating H3K79. We also show that Dot1l is induced during brown fat cell differentiation and by cold exposure and that Dot1l and its H3K79 methyltransferase activity is required for thermogenic gene program. Furthermore, we demonstrate that Dot1l ablation in mice using Ucp1-Cre prevents activation of Ucp1 and other target genes to reduce thermogenic capacity and energy expenditure, promoting adiposity. Hence, Dot1l plays a critical role in the thermogenic program and may present as a future target for obesity therapeutics.

Reprogramming of cancer cells into induced pluripotent stem cells (iPSCs) opens up the possibility of converting malignant cells into any cell type, including those best suited to be developed as cancer vaccines. Mouse models are needed to evaluate and optimize the therapeutic efficacy of such novel cancer vaccines. However, only human cancer cell lines have been reported as being reprogrammed into iPSCs. Here, we report a proof-of-principle study which shows that mouse cancer cells can be reprogrammed into iPSCs that are capable of subsequent differentiation. Four canonical reprogramming transcription factors, Oct3/4, Sox2, Klf4, and c-Myc, were introduced by plasmid transfection into mouse Lewis lung carcinoma D122 harboring Nanog-GFP reporter. Green fluorescent cells were found clustered into embryonic stem cell (ESC)-like colonies expressing ESC markers, Oct4 and SSEA-1. Bisulfite genomic sequencing analyses of these cells revealed hypomethylation of the Nanog promoter. The expression of a host of pluripotency genes by these reprogrammed cells at levels similar to those of ESCs was confirmed by quantitative real-time PCR. Functional pluripotency of the reprogrammed cells was demonstrated by their ability to form embryoid bodies and differentiate into neuronal progenitors on retinoic acid treatment. This study indicates the feasibility of developing iPSC-based experimental cancer vaccines for immunotherapy in mouse models.