The death effector domain-containing DEDD forms a complex with Akt and Hsp90, and supports their stability

Autophagy induction regulates aquaporin 3-mediated skin fibroblasts aging

BACKGROUND

Long- and short-term ultraviolet (UV) exposure have distinct biological effects on human fibroblasts.

OBJECTIVES

This study aimed to elucidate the underlying mechanisms of the biological effects of UV exposure on human skin fibroblasts.

METHOD

We subjected human skin fibroblast cells with or without AQP3, DEDD, or Beclin1 manipulation to UVA treatment and evaluated autophagy and senescence/aging in them.

RESULTS

Short-term UVA irradiation induced autophagy and upregulated AQP3 but not senescence, whereas long-term UVA irradiation inhibited autophagy, AQP3, and senescence/aging in vitro and in vivo. Silencing AQP3 abolished short-term UVA irradiation-induced autophagy and led to cellular senescence, whereas AQP3 overexpression partially rescued the senescence and autophagy inhibition induced by long-term UVA exposure in vitro. Mechanistically, the transcription factor JUN was found to bind to the AQP3 promoter to activate its transcription following short-term UVA exposure. Subsequently, AQP3 interacted with DEDD to induce its ubiquitination-mediated degradation and promote autophagy, and bound to Beclin1 to directly activate autophagy. Finally, autophagy induced by AQP3 overexpression robustly prevented UVA-induced senescence/aging in vitro and in vivo.

CONCLUSIONS

Thus, our study indicates that AQP3 controls skin fibroblasts photoaging by regulating autophagy and represents a potential target for future interventions against skin aging.

Low DEDD expression in breast cancer cells indicates higher sensitivity to the Bcl-2-specific inhibitor ABT-199

As a proapoptotic death effect domain (DED)-containing protein, DED-containing DNA-binding protein (DEDD) has been demonstrated to inhibit tumor growth, invasion and metastasis in our previous studies. Here, we demonstrated that knockdown of DEDD in MCF-7 cells resulted in characteristic drug resistance to doxorubicin and paclitaxel, and overexpression of DEDD in MDA-MB-231 cells increased their sensitivity to doxorubicin and paclitaxel. The expression levels of DEDD were positively correlated with Bcl-2 in breast cancer cell lines as well as in human breast cancer tissue. Knockdown of DEDD downregulated the transcriptional activity of the bcl-2 gene and shortened the time for Bcl-2 degradation. DEDD interacts with and stabilizes Bcl-2, and breast cancer cells with low DEDD expression were more sensitive to treatment with a BH3 mimetic, ABT-199, than were those with high DEDD expression. In total, our findings highlight a new strategy for treating breast cancer with no/low DEDD expression by targeting Bcl-2 with the BH3 mimetic ABT-199.

MCL1 and DEDD Promote Urothelial Carcinoma Progression

Focal amplification of chromosome 1q23.3 in patients with advanced primary or relapsed urothelial carcinomas is associated with poor survival. We interrogated chromosome 1q23.3 and the nearby focal amplicon 1q21.3, as both are associated with increased lymph node disease in patients with urothelial carcinoma. Specifically, we assessed whether the oncogene MCL1 that resides in 1q21.3 and the genes that reside in the 1q23.3 amplicon were required for the proliferation or survival of urothelial carcinoma. We observed that suppressing MCL1 or the death effector domain-containing protein (DEDD) in the cells that harbor amplifications of 1q21.3 or 1q23.3, respectively, inhibited cell proliferation. We also found that overexpression of MCL1 or DEDD increased anchorage independence growth in vitro and increased experimental metastasis in vivo in the nonamplified urothelial carcinoma cell line, RT112. The expression of MCL1 confers resistance to a range of apoptosis inducers, while the expression of DEDD led to resistance to TNFα-induced apoptosis. These observations identify MCL1 and DEDD as genes that contribute to aggressive urothelial carcinoma. IMPLICATIONS: These studies identify MCL1 and DEDD as genes that contribute to aggressive urothelial carcinomas.

The decidua-the maternal bed embracing the embryo-maintains the pregnancy

The decidua has been known as maternal uterine tissue, which plays essential roles in protecting the embryo from being attacked by maternal immune cells and provides nutritional support for the developing embryo prior to placenta formation. However, there are questions that still remain to be answered: (1) How does the decidua supply nutrition and provide a physical scaffold for the growing embryo, before placental vascular connection is established? (2) How is the balance between preventing an anti-embryo immune response and protecting both embryo and mother from infections established? To understand basic personas in decidual tissues, we review the structure of the decidua composed of terminally differentiated uterine stromal cells, blood vessels, and a number of repertoire of uterine local immune cells, including the well-known uterine natural killer (uNK) cells and recently discovered innate lymphoid cells (ILCs). Decidual macrophages and uterine dendritic cells (DCs) are supposed to modulate adaptive immunity via balancing cytokines and promoting generation of regulatory T (Treg) cells. During decidualization, vascular and tissue remodeling in the uterus provide nutritional and physical support for the developing embryo. Secretion of various cytokines and chemokines from both the embryo and the decidual cells activates multiple signaling network between the mother and the embryo upon implantation. Defects in the decidual development during early pregnancy result in loss of pregnancy or complications in later gestational stage.

Oral supplementations with L-glutamine or L-alanyl-L-glutamine do not change metabolic alterations induced by long-term high-fat diet in the B6.129F2/J mouse model of insulin resistance

In this work, we aimed to investigate the effects of long-term supplementations with L-glutamine or L-alanyl-L-glutamine in the high-fat diet (HFD)-fed B6.129SF2/J mouse model over insulin sensitivity response and signaling, oxidative stress markers, metabolism and HSP70 expression. Mice were fed in a standard low-fat diet (STA) or a HFD for 20 weeks. In the 21th week, mice from the HFD group were allocated in five groups and supplemented for additional 8 weeks with different amino acids: HFD control group (HFD-Con), HFD + dipeptide L-alanyl-L-glutamine group (HFD-Dip), HFD + L-alanine group (HFD-Ala), HFD + L-glutamine group (HFD-Gln), or the HFD + L-alanine + L-glutamine (in their free forms) group (HFD-Ala + Gln). HFD induced higher body weight, fat pad, fasted glucose, and total cholesterol in comparison with STA group. Amino acid supplementations did not induce any modifications in these parameters. Although insulin tolerance tests indicated insulin resistance in all HFD groups, amino acid supplementations did not improve insulin sensitivity in the present model. There were also no significant differences in the immunocontents of insulin receptor, Akt, and Toll-like receptor-4. Notably, total 70 kDa heat shock protein (HSP72 + HSP73) contents in the liver was markedly increased in HFD-Con group as compared to STA group, which might suggest that insulin resistance is only in the beginning. Apparently, B6.129SF2/J mice are more resistant to the harmful effects of HFD through a mechanism that may include gut adaptation, reducing the absorption of nutrients, including amino acids, which may explain the lack of improvements in our intervention.

DEDD interacts with PI3KC3 to activate autophagy and attenuate epithelial-mesenchymal transition in human breast cancer

Epithelial-to-mesenchymal transition (EMT), a crucial developmental program, contributes to cancer invasion and metastasis. In this study, we show that death-effector domain-containing DNA-binding protein (DEDD) attenuates EMT and acts as an endogenous suppressor of tumor growth and metastasis. We found that expression levels of DEDD were conversely correlated with poor prognosis in patients with breast and colon cancer. Both in vitro and in vivo, overexpression of DEDD attenuated the invasive phenotype of highly metastatic cells, whereas silencing of DEDD promoted the invasion of nonmetastatic cells. Via direct interaction with the class III PI-3-kinase (PI3KC3)/Beclin1, DEDD activated autophagy and induced the degradation of Snail and Twist, two master regulators of EMT. The DEDD-PI3KC3 interaction led to stabilization of PI3KC3, which further contributed to autophagy and the degradation of Snail and Twist. Together, our findings highlight a novel mechanism in which the intracellular signaling protein DEDD functions as an endogenous tumor suppressor. DEDD expression therefore may represent a prognostic marker and potential therapeutic target for the prevention and treatment of cancer metastasis.

Developmental regulation of decidual cell polyploidy at the site of implantation

Polyploidy has been reported in several animal cells, as well as within humans; however the mechanism of developmental regulation of this process remains poorly understood. Polyploidy occurs in normal biologic processes as well as in pathologic states. Decidual polyploid cells are terminally differentiated cells with a critical role in continued uterine development during embryo implantation and growth. Here we review the mechanisms involved in polyploidy cell formation in normal developmental processes, with focus on known regulatory aspects in decidual cells.

Death effector domain-containing protein (DEDD) is required for uterine decidualization during early pregnancy in mice

During intrauterine life, the mammalian embryo survives via its physical connection to the mother. The uterine decidua, which differentiates from stromal cells after implantation in a process known as decidualization, plays essential roles in supporting embryonic growth before establishment of the placenta. Here we show that female mice lacking death effector domain-containing protein (DEDD) are infertile owing to unsuccessful decidualization. In uteri of Dedd-/- mice, development of the decidual zone and the surrounding edema after embryonic implantation was defective. This was subsequently accompanied by disintegration of implantation site structure, leading to embryonic death before placentation. Polyploidization, a hallmark of mature decidual cells, was attenuated in DEDD-deficient cells during decidualization. Such inefficient decidualization appeared to be caused by decreased Akt levels, since polyploidization was restored in DEDD-deficient decidual cells by overexpression of Akt. In addition, we showed that DEDD associates with and stabilizes cyclin D3, an important element in polyploidization, and that overexpression of cyclin D3 in DEDD-deficient cells improved polyploidization. These results indicate that DEDD is indispensable for the establishment of an adequate uterine environment to support early pregnancy in mice.