Aberrant activation of AKT disturbs the proliferation, survival and metabolic homeostasis of various human cancers. Thus, it is critical to understand the upstream signalling pathways governing AKT ...activation. Here, we report that AKT undergoes SETDB1-mediated lysine methylation to promote its activation, which is antagonized by the Jumonji-family demethylase KDM4B. Notably, compared with wild-type mice, mice harbouring non-methylated mutant Akt1 not only exhibited reduced body size but were also less prone to carcinogen-induced skin tumours, in part due to reduced AKT activation. Mechanistically, the interaction of phosphatidylinositol (3,4,5)-trisphosphate with AKT facilitates its interaction with SETDB1 for subsequent AKT methylation, which in turn sustains AKT phosphorylation. Pathologically, genetic alterations, including SETDB1 amplification, aberrantly promote AKT methylation to facilitate its activation and oncogenic functions. Thus, AKT methylation is an important step, synergizing with PI3K signalling to control AKT activation. This suggests that targeting SETDB1 signalling could be a potential therapeutic strategy for combatting hyperactive AKT-driven cancers.
In mammals, nonrenewable primordial follicles are activated in an orderly manner to maintain the longevity of reproductive life. Mammalian target of rapamycin (mTOR)-KIT ligand (KITL) signaling in ...pre-granulosa cells and phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-forkhead Box O3a (FOXO3a) signaling in oocytes are important for primordial follicle activation. The activation process is accompanied by the enhancement of energy metabolism, but the causal relationship is unclear. In the present study, the levels of glycolysis-related proteins GLUT4, HK1, PFKL, and PKM2 were significantly increased in granulosa cells but were decreased in oocytes during the mouse primordial-to-primary follicle transition. Both short-term pyruvate deprivation in vitro and acute fasting in vivo increased the glycolysis-related gene and protein levels, decreased AMPK activity, and increased mTOR activity in mouse ovaries. The downstream pathways Akt and FOXO3a were phosphorylated, resulting in mouse primordial follicle activation. The blockade of glycolysis by 2-deoxyglucose (2-DG), but not the blockade of the communication network between pre-granulosa cells and oocyte by KIT inhibitor ISCK03, decreased short-term pyruvate deprivation-promoted mTOR activity. Glycolysis was also increased in human granulosa cells during the primordial-to-primary follicle transition, and short-term pyruvate deprivation promoted the activation of human primordial follicles by increasing the glycolysis-related protein levels and mTOR activity in ovarian tissues. Taken together, the enhanced glycolysis in granulosa cells promotes the activation of primordial follicles through mTOR signaling. These findings provide new insight into the relationship between glycolytic disorders and POI/PCOS.
The majority of ovarian primordial follicles are preserved in a dormant state to maintain the female reproductive lifespan, and only a few primordial follicles are activated to enter the growing ...follicle pool in each wave. Recent studies have shown that primordial follicular activation depends on mammalian target of rapamycin complex 1 (mTORC1)‐KIT ligand (KITL) signaling in pre‐granulosa cells and its receptor (KIT)‐phosphoinositol 3 kinase (PI3K) signaling in oocytes. However, the upstream regulator of mTORC1 signaling is unclear. The results of the present study showed that the phosphorylated mitogen‐activated protein kinase3/1 (MAPK3/1) protein is expressed in some primordial follicles and all growing follicles. Culture of 3 days post‐parturition (dpp) ovaries with the MAPK3/1 signaling inhibitor U0126 significantly reduced the number of activated follicles and was accompanied by dramatically reduced granulosa cell proliferation and increased oocyte apoptosis. Western blot and immunofluorescence analyses showed that U0126 significantly decreased the phosphorylation levels of Tsc2, S6K1, and rpS6 and the expression of KITL, indicating that U0126 inhibits mTORC1‐KITL signaling. Furthermore, U0126 decreased the phosphorylation levels of Akt, resulting in a decreased number of oocytes with Foxo3 nuclear export. To further investigate MAPK3/1 signaling in primordial follicle activation, we used phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibitor bpV(HOpic) to promote primordial follicle activation. In this model, U0126 also inhibited the activation of primordial follicles and mTORC1 signaling. Thus, these results suggest that MAPK3/1 participates in primordial follicle activation through mTORC1‐KITL signaling.
Primordial follicular activation depends on mammalian target of rapamycin complex 1 (mTORC1)‐KIT ligand (KITL) signaling in pre‐granulosa cells and its receptor (KIT)‐phosphoinositol 3 kinase (PI3K) signaling in oocytes. Here, we have shown that MAPK3/1 signaling participates in the activation of primordial follicles through mTORC1 signaling and the expression of KITL in pre‐granulosa cells to activate the PI3K‐Akt pathway.
There is a growing interest in the role of timing of daily behaviors in improving health. However, little is known about the optimal timing of physical activity to maximize health benefits. We ...perform a cohort study of 92,139 UK Biobank participants with valid accelerometer data and all-cause and cause-specific mortality outcomes, comprising over 7 years of median follow-up (638,825 person-years). Moderate-to-vigorous intensity physical activity (MVPA) at any time of day is associated with lower risks for all-cause, cardiovascular disease, and cancer mortality. In addition, compared with morning group (>50% of daily MVPA during 05:00-11:00), midday-afternoon (11:00-17:00) and mixed MVPA timing groups, but not evening group (17:00-24:00), have lower risks of all-cause and cardiovascular disease mortality. These protective associations are more pronounced among the elderly, males, less physically active participants, or those with preexisting cardiovascular diseases. Here, we show that MVPA timing may have the potential to improve public health.
3-phosphoinositide-dependent protein kinase-1 (PDK1) acts as a master kinase of protein kinase A, G, and C family (AGC) kinase to predominantly govern cell survival, proliferation, and metabolic ...homeostasis. Although the regulations to PDK1 downstream substrates such as protein kinase B (AKT) and ribosomal protein S6 kinase beta (S6K) have been well established, the upstream regulators of PDK1, especially its degrader, has not been defined yet.
A clustered regularly interspaced short palindromic repeats (CRISPR)-based E3 ligase screening approach was employed to identify the E3 ubiquitin ligase for degrading PDK1. Western blotting, immunoprecipitation assays and immunofluorescence (IF) staining were performed to detect the interaction or location of PDK1 with speckle-type POZ protein (SPOP). Immunohistochemistry (IHC) staining was used to study the expression of PDK1 and SPOP in prostate cancer tissues. In vivo and in vitro ubiquitination assays were performed to measure the ubiquitination conjugation of PDK1 by SPOP. In vitro kinase assays and mass spectrometry approach were carried out to identify casein kinase 1 (CK1) and glycogen synthase kinase 3 (GSK3)-mediated PDK1 phosphorylation. The biological effects of PDK1 mutations and correlation with SPOP mutations were performed with colony formation, soft agar assays and in vivo xenograft mouse models.
We identified that PDK1 underwent SPOP-mediated ubiquitination and subsequent proteasome-dependent degradation. Specifically, SPOP directly bound PDK1 by the consensus degron in a CK1/GSK3β-mediated phosphorylation dependent manner. Pathologically, prostate cancer patients associated mutations of SPOP impaired PDK1 degradation and thus activated the AKT kinase, resulting in tumor malignancies. Meanwhile, mutations that occurred around or within the PDK1 degron, by either blocking SPOP to bind the degron or inhibiting CK1 or GSK3β-mediated PDK1 phosphorylation, could markedly evade SPOP-mediated PDK1 degradation, and played potently oncogenic roles via activating the AKT kinase.
Our results not only reveal a physiological regulation of PDK1 by E3 ligase SPOP, but also highlight the oncogenic roles of loss-of-function mutations of SPOP or gain-of-function mutations of PDK1 in tumorigenesis through activating the AKT kinase.
Copper plays pivotal roles in metabolic homoeostasis, but its potential role in human tumorigenesis is not well defined. Here, it is revealed that copper activates the phosphoinositide 3‐kinase ...(PI3K)‐protein kinase B (PKB, also termed AKT) oncogenic signaling pathway to facilitate tumorigenesis. Mechanistically, copper binds 3‐phosphoinositide dependent protein kinase 1 (PDK1), in turn promotes PDK1 binding and subsequently activates its downstream substrate AKT to facilitate tumorigenesis. Blocking the copper transporter 1 (CTR1)‐copper axis by either depleting CTR1 or through the use of copper chelators diminishes the AKT signaling and reduces tumorigenesis. In support of an oncogenic role for CTR1, the authors find that CTR1 is abnormally elevated in breast cancer, and is subjected by NEDD4 like E3 ubiquitin protein ligase (Nedd4l)‐mediated negative regulation through ubiquitination and subsequent degradation. Accordingly, Nedd4l displays a tumor suppressive function by suppressing the CTR1‐AKT signaling. Thus, the findings identify a novel regulatory crosstalk between the Nedd4l‐CTR1‐copper axis and the PDK1‐AKT oncogenic signaling, and highlight the therapeutic relevance of targeting the CTR1‐copper node for the treatment of hyperactive AKT‐driven cancers.
Besides playing pivotal roles in metabolic homoeostasis, copper also binds PDK1 to activate its downstream AKT kinase, which in turn facilitates tumorigenesis. Meanwhile, the copper transporter 1 (CTR1) is negatively regulated by Nedd4l‐mediated ubiquitination and subsequent degradation, indicating a novel regulatory crosstalk between the Nedd4l‐CTR1‐copper axis and the PDK1‐AKT oncogenic signaling to govern tumorigenesis.
Abstract
With rapid urbanization in China, an increasing number of urban dwellers are migrating to rural areas, becoming “new villagers”. This phenomenon provides both opportunities and challenges ...for rural revitalization. This study aims to examine the community integration dilemmas of these new villagers from the perspective of social space production theory. Through oral history investigations, in-depth interviews and participant observations, this qualitative study explores the integration predicaments of new villagers across four dimensions—living space, production space, cultural space, and social space. The findings indicate that the integration dilemmas arise from disparities between new villagers and native villagers in status, cultural identity, values, and customs. New villagers face risks of exclusion in obtaining living space, cultural conflicts in production activities, value clashes with traditional rural culture, and social closure from existing rural networks. To better integrate new villagers into local communities, fostering cultural communication, shaping common values, and restructuring rural space are essential, providing insights for rural talent retention policies. This research offers implications for rural talent revitalization mechanisms in the context of urban–rural migration in China.
Porcine spermatozoa are stored in the oviductal isthmus after natural mating, and the number of spermatozoa is increased in the oviductal ampulla when the mature cumulus-oocyte complexes (COCs) are ...transferred into the ampulla. However, the mechanism is unclear. Herein, natriuretic peptide type C (NPPC) was mainly expressed in porcine ampullary epithelial cells, whereas its cognate receptor natriuretic peptide receptor 2 (NPR2) was located on the neck and the midpiece of porcine spermatozoa. NPPC increased sperm motility and intracellular Ca
levels, and induced sperm release from oviduct isthmic cell aggregates. These actions of NPPC were blocked by the cyclic guanosine monophosphate (cGMP)-sensitive cyclic nucleotide-gated (CNG) channel inhibitor
-Diltiazem. Moreover, porcine COCs acquired the ability to promote NPPC expression in the ampullary epithelial cells when the immature COCs were induced to maturation by epidermal growth factor (EGF). Simultaneously, transforming growth factor-β ligand 1 (TGFB1) levels were dramatically increased in the cumulus cells of the mature COCs. The addition of TGFB1 promoted NPPC expression in the ampullary epithelial cells, and the mature COC-induced NPPC was blocked by the transforming growth factor-β type 1 receptor (TGFBR1) inhibitor SD208. Taken together, the mature COCs promote NPPC expression in the ampullae via TGF-β signaling, and NPPC is required for the release of porcine spermatozoa from the oviduct isthmic cells.
MicroRNAs (miRNAs) control the expression of approximately 60% of protein-coding genes and regulate cell metabolism, proliferation, differentiation, and apoptosis. Notably, aberrant expression of ...miRNAs contributes to several diseases including cancer. Accumulating evidence indicates that miRNAs play important roles in EMT, genesis of cancer stem cells, cancer metabolism and carcinogenesis. Aberrant expression of miRNAs triggers tumor initiation, progression and poor prognosis of cancer patients. Accordingly, oncogenic miRNAs have emerged as diagnostic biomarkers and targets for novel anti-cancer drug discovery. However, the mechanisms of miRNAs contriving tumorigenesis are not completely understood. This review aims to clarify the identification of tumorspecific miRNAs, verification of oncogenic miRNA signatures, and dynamic study of oncogenic miRNAs in cancer initiation and development. Despite sound progress in miRNA-mediated anticancer therapy, several barriers like drug stability, immunogenicity, off-target effects and toxicities still remain. We hope our review could stimulate the further study of miRNAs in cancer research field, which may lead to new insights into the mechanisms of carcinogenesis and create new avenues for targeted cancer therapy.
Set8 is critically involved in transcription regulation, cell cycle progression and genomic stability. Emerging evidence has revealed that E3 ubiquitin ligases such as CRL4
cdt2
and SCF
Skp2
regulate ...Set8 protein abundance. However, it is unclear whether other E3 ligase(s) could govern Set8 level for proper cell cycle progression in response to genotoxic stress such as UV irradiation. Recently, we report that the SCF
β-TRCP
complex regulates Set8 protein stability by targeting it for ubiquitination and subsequent degradation. Notably, Set8 interacts with the SCF
β-TRCP
E3 ligase complex. We further revealed a critical role of CKI in SCF
β-TRCP
-mediated degradation of Set8. Mechanistically, CKI-mediated phosphorylation of Set8 at the S253 site promotes its destruction by SCF
β-TRCP
. Importantly, SCF
β-TRCP
-dependent Set8 destruction also contributes to the tight control of cell proliferation and cell cycle progression, in response to UV irradiation. Here, we summarize our new findings regarding the crucial role of β-TRCP in CKI-mediated Set8 degradation, which could provide new evidence to support that dysregulation of a tight regulatory network of Set8 could lead to aberrant cell cycle process.
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