Forkhead box O (Foxo) transcription factors may be involved in the salutary effect of dietary restriction (DR). This study examined the role of Foxo3 in lifespan extension and cancer suppression in DR mice. Wild-type (WT) and Foxo3-knockout heterozygous ((+/-) ) and homozygous ((-/-) ) mice were subjected to a 30% DR regimen initiated at 12 weeks of age. Control mice were fed ad libitum (AL) throughout the study. In contrast to WT mice, DR did not significantly extend the lifespan of Foxo3(+/-) or Foxo3(-/-) mice. However, DR reduced the prevalence of tumors at death in WT, Foxo3(+/-) , and Foxo3(-/-) mice. These results indicate the necessity of Foxo3 for lifespan extension but not cancer suppression by DR. The findings in Foxo3(+/-) mice contrast with those in Foxo1(+/-) mice reported previously by our laboratory suggest differential regulation of cancer and lifespan by DR via Foxo1 and Foxo3.

The forkhead box O (FOXO) family has been extensively investigated in aging and metabolism, but its role in tissue-repair processes remains largely unknown. Herein, we clarify the molecular aspect of the FOXO family in skin wound healing. We demonstrated that Foxo1 and Foxo3a were both up-regulated during murine skin wound healing. Partial knockout of Foxo1 in Foxo1(+/-) mice throughout the body led to accelerated skin wound healing with enhanced keratinocyte migration, reduced granulation tissue formation, and decreased collagen density, accompanied by an attenuated inflammatory response, but we observed no wound phenotype in Foxo3a(-/-) mice. Fibroblast growth factor 2, adiponectin, and notch1 genes were significantly increased at wound sites in Foxo1(+/-) mice, along with markedly altered extracellular signal-regulated kinase 1/2 and AKT phosphorylation. Similarly, transient knockdown of Foxo1 at the wound site by local delivery of antisense oligodeoxynucleotides enhanced skin wound healing. The link between FOXO1 and scarring extends to patients, in particular keloid scars, where we see FOXO1 expression markedly increased in fibroblasts and inflammatory cells within the otherwise normal dermis. This occurs in the immediate vicinity of the keloid by comparison to the center of the mature keloid, indicating that FOXO1 is associated with the overgrowth of this fibrotic response into adjacent normal skin. Overall, our data indicate that molecular targeting of FOXO1 may improve the quality of healing and reduce pathological scarring.

Activated macrophages at wound sites release many cytokines which positively affect skin wound healing. However, the molecular mechanisms controlling cytokine secretion from macrophages have not been elucidated. In the present study, we performed an RT‐PCR analysis and found that 19 small GTPase Rab isoforms were expressed at skin wound sites, with six of them (i.e. Rab3B, Rab27B, Rab30, Rab33A, Rab37, and Rab40C) being upregulated during the inflammation and proliferation/migration phase of skin repair. We also found that gene expression of Rab37 in murine primary and RAW264.7 macrophages was significantly induced after stimulation with LPS. Overexpression of wild type and constitutively active Rab37 in RAW264.7 cells significantly increased TNF‐α secretion, whereas knockdown of Rab37 by siRNA significantly decreased it. We also identified 29 putative Rab37‐interacting proteins, including the membrane fusion regulating Munc13‐1, using liquid chromatography/linear ion trap mass spectrometry (LC‐MS/MS). Immunocytochemical analysis further revealed that TNF‐α‐containing vesicles were colocalized with both Rab37 and Munc13‐1 in activated macrophages. Knockdown of Munc13‐1 by siRNA significantly decreased TNF‐α secretion. Taken together, these findings demonstrate that Rab37 interacts with Munc13‐1 to control TNF‐α secretion from activated macrophages.

Knowledge of genes essential for the life-extending effect of dietary restriction (DR) in mammals is incomplete. In this study, we found that neuropeptide Y (Npy), which mediates physiological adaptations to energy deficits, is an essential link between DR and longevity in mice. The lifespan-prolonging effect of lifelong 30% DR was attenuated in Npy-null mice, as was the effect on the occurrence of spontaneous tumors and oxidative stress responses in comparison to wild-type mice. In contrast, the physiological processes activated during adaptation to DR, including inhibition of anabolic signaling molecules (insulin and insulin-like growth factor-1), modulation of adipokine and corticosterone levels, and preferential fatty acid oxidation, were unaffected by the absence of Npy. These results suggest a key role for Npy in mediating the effects of DR. We also provide evidence that most of the physiological adaptations to DR could be achieved in mice without Npy.

An orexigenic hormone, neuropeptide Y (NPY), plays a role not only in the hypothalamic regulation of appetite, but also in the peripheral regulation of lipid metabolism. However, the intracellular mechanisms triggered by NPY to regulate lipid metabolism are poorly understood. Here we report that NPY deficiency reduces white adipose tissue (WAT) mass and ameliorates the age‐related imbalance of adipose tissue metabolism in mice. Gene expression involved in adipogenesis/lipogenesis was found to decrease, whereas proteins involved in lipolysis increased in gonadal WAT (gWAT) of NPY‐knockout mice. These changes were associated with an activated SIRT1‐ and PPARγ‐mediated pathway. Moreover, the age‐related decrease of de novo lipogenesis in gWAT and thermogenesis in inguinal WAT was inhibited by NPY deficiency. Further analysis using 3T3‐L1 cells showed that NPY inhibited lipolysis through the Y1 receptor and enhanced lipogenesis following a reduction in cAMP response element‐binding protein (CREB) and SIRT1 protein expression. Therefore, NPY appears to act as a key regulator of adipose tissue metabolism via the CREB‐SIRT1 signaling pathway. Taken together, NPY deficiency reduces adiposity and ameliorates the agerelated imbalance of adipose tissue metabolism, suggesting that antagonism of NPY may be a promising target for drug development to prevent age‐related metabolic diseases.—Park, S., Fujishita, C., Komatsu, T., Kim, S. E., Chiba, T., Mori, R., Shimokawa, I., NPY antagonism reduces adiposity and attenuates age‐related imbalance of adipose tissue metabolism. FASEB J. 28, 5337–5348 (2014). www.fasebj.org