Hypoxia is amongst the most widespread and pressing problems in aquatic environments. Here we demonstrate that fish (Oryzias melastigma) exposed to hypoxia show reproductive impairments (retarded gonad development, decrease in sperm count and sperm motility) in F1 and F2 generations despite these progenies (and their germ cells) having never been exposed to hypoxia. We further show that the observed transgenerational reproductive impairments are associated with a differential methylation pattern of specific genes in sperm of both F0 and F2 coupled with relevant transcriptomic and proteomic alterations, which may impair spermatogenesis. The discovered transgenerational and epigenetic effects suggest that hypoxia might pose a dramatic and long-lasting threat to the sustainability of fish populations. Because the genes regulating spermatogenesis and epigenetic modifications are highly conserved among vertebrates, these results may also shed light on the potential transgenerational effects of hypoxia on other vertebrates, including humans.
Stanniocalcin-1 (STC1) is an endocrine hormone originally discovered in the corpuscles of Stannius, endocrine glands on kidneys of bony fishes, and also has been identified in mammals. The mammalian STC1 gene is widely expressed in various tissues and appears to be involved in diverse biological processes. There is growing evidence to suggest that altered patterns of gene expression have a role in human cancer development. Recently STC1 has been identified as a stimulator of mitochondrial respiration and has been hypothesized to be functionally related to the Warburg effect, of which hypoxia-inducible factor (HIF)-1 plays a key role in reprogramming tumor metabolism. This prompted us to examine the involvement of HIF-1 in the regulation of STC1 expression in tumor hypoxia. Our data reveal that hypoxia can stimulate STC1 gene expression in various human cancer cell lines, including those derived from colon carcinomas, nasopharyngeal cancer (CNE-2, HONE-1, HK-1), and ovarian cancer (CaOV3, OVCAR3, SKOV3). By far, the greatest response was observed in CNE-2 cells. In further studies on CNE-2 cells, desferrioxamine, cobalt chloride, and O2 depletion all increased HIF-1α protein and STC1 mRNA levels. Desferrioxamine treatment, when coupled with Fe replenishment, abolished these effects. RNA interference studies further confirmed that endogenous HIF-1α was a key factor in hypoxia-induced STC1 expression. The ability of vascular endothelial growth factor to stimulate STC1 expression in CNE-2 cells was comparatively low. Collectively, the present findings provide the first evidence of HIF-1 regulation of STC1 expression in human cancer cells. The studies have implications as to the role of STC1 in hypoxia induced adaptive responses in tumor cells.
p53 mediates DNA damage-induced cell-cycle arrest, apoptosis, or senescence, and it is controlled by Mdm2, which mainly ubiquitinates p53 in the nucleus and promotes p53 nuclear export and degradation. By searching for the kinases responsible for Mdm2 S163 phosphorylation under genotoxic stress, we identified S6K1 as a multifaceted regulator of Mdm2. DNA damage activates mTOR-S6K1 through p38a MAPK. The activated S6K1 forms a tighter complex with Mdm2, inhibits Mdm2-mediated p53 ubiquitination, and promotes p53 induction, in addition to phosphorylating Mdm2 on S163. Deactivation of mTOR-S6K1 signalling leads to Mdm2 nuclear translocation, which is facilitated by S163 phosphorylation, a reduction in p53 induction, and an alteration in p53-dependent cell death. These findings thus establish mTOR-S6K1 as a novel regulator of p53 in DNA damage response and likely in tumorigenesis. S6K1-Mdm2 interaction presents a route for cells to incorporate the metabolic/energy cues into DNA damage response and links the aging-controlling Mdm2-p53 and mTOR-S6K pathways.
Objectives Patients with colorectal cancer (CRC) may be susceptible to the coronavirus disease-2019 (COVID-19). However, anti-CRC/COVID-19 treatment options are currently unavailable. Since niacin is a vitamin with cytoprotective and anti-inflammatory functions, this study aimed to evaluate the possible functional roles and underlying mechanisms of action of niacin as an anti-COVID-19 and -CRC therapy. Interventions We used a series of network pharmacology-based and computational analyses to understand and characterize the binding capacity, biological functions, pharmacological targets and therapeutic mechanisms of niacin in CRC/COVID-19. Measurements and main results We revealed the clinical characteristics of CRC patients and COVID-19 patients, including predisposing genes, survival rate and prognosis. Moreover, the results of molecular docking analysis indicated that niacin exerted effective binding capacity in COVID-19. Further, we disclosed the targets, biological functions and signaling pathways of niacin in CRC/COVID-19. The analysis indicated that niacin could help in treating CRC/COVID-19 through cytoprotection, enhancement of immunologic functions, inhibition of inflammatory reactions and regulation of cellular microenvironment. Furthermore, five core pharmacological targets of niacin in CRC/COVID-19 were also identified, including BCL2L1, PTGS2, IL1B, IFNG and SERPINE1. Conclusions This study, for the first time, revealed the niacin-associated molecular functions and pharmacological targets for treating CRC/COVID-19, as COVID-19 remains a serious pandemic. But the findings were not validated in actual CRC patients infected with COVID-19, so further investigation is needed to confirm the potential use of niacin for treating CRC/COVID-19.
Despite the widespread observations on the osteogenic effects of magnesium ion (Mg2+), the diverse roles of Mg2+ during bone healing have not been systematically dissected. Here, we reveal a previously unknown, biphasic mode of action of Mg2+ in bone repair. During the early inflammation phase, Mg2+ contributes to an upregulated expression of transient receptor potential cation channel member 7 (TRPM7), and a TRPM7-dependent influx of Mg2+ in the monocyte-macrophage lineage, resulting in the cleavage and nuclear accumulation of TRPM7-cleaved kinase fragments (M7CKs). This then triggers the phosphorylation of Histone H3 at serine 10, in a TRPM7-dependent manner at the promoters of inflammatory cytokines, leading to the formation of a pro-osteogenic immune microenvironment. In the later remodeling phase, however, the continued exposure of Mg2+ not only lead to the over-activation of NF-κB signaling in macrophages and increased number of osteoclastic-like cells but also decelerates bone maturation through the suppression of hydroxyapatite precipitation. Thus, the negative effects of Mg2+ on osteogenesis can override the initial pro-osteogenic benefits of Mg2+. Taken together, this study establishes a paradigm shift in the understanding of the diverse and multifaceted roles of Mg2+ in bone healing.
DNA damage triggers Atm-and/or Atr-dependent signaling pathways to control cell cycle progression, apoptosis, and DNA repair. However, how Atm and Atr are activated is not fully understood. One of the downstream targets of Atm is non-receptor tyrosine kinase c-Abl, which is phosphorylated and activated by Atm. The current view is that c-Abl relays pro-apoptotic signals from Atm to p73 and p53. Here we show that c-Abl deficiency resulted in a broad spectrum of defects in cell response to genotoxic stress, including activation of Chk1 and Chk2, activation of p53, nuclear foci formation, apoptosis, and DNA repair, suggesting that c-Abl might also act upstream of the DNA damage-activated signaling cascades in addition to its role in p73 and p53 regulation. Indeed, we found that c-Abl is required for proper activation of both Atm and Atr. c-Abl is bound to the chromatin and shows enhanced interaction with Atm and Atr in response to DNA damage. c-Abl can phosphorylate Atr on Y291 and Y310 and this phosphorylation appears to have a positive role in Atr activation under genotoxic stress. These findings suggest that Atm-mediated c-Abl activation in cell response to double-stranded DNA breaks might facilitate the activation of both Atm and Atr to regulate their downstream cellular events. Cell Death and Differentiation (2011) 18, 5-15; doi:10.1038/cdd.2010; published online 27 August 2010 DNA damage can be caused by exogenous or endogenous factors such as ionizing radiation (IR), chemotherapeutic drugs, and stalled replication forks. 1 It is believed that various DNA lesions are eventually converted to double-stranded breaks (DSBs) and/or single-stranded DNA (ssDNA or SSBs), where sensors, mediators, transducers, and effectors assemble to form nuclear foci, which function as centers of signal propagation. At the core of the signaling network are PI-3 kinase-like kinases (PIKKs), including Atm, Atr and DNA-PKcs. 2 Atm is mainly activated by DSBs, whereas Atr responds to various DNA lesions. 3 Atm and Atr are recruited to the nuclear foci by the MRN (Mre11-Rad50-NBS) complex and ATRIP, respectively, 4,5 where they phosphorylate proteins such as p53, Chk1, Chk2, and H2AX, to activate cell cycle checkpoints and/or induce apoptosis. 6 Phosphorylation of Chk1 and Chk2 by Atr and Atm is facilitated by a group of nuclear foci proteins called mediators, for example, Brca1, TopBP1, and 53BP1. Furthermore, the nuclear foci also function as repair centers. 7 DSB repair is believed to involve an Atm to Atr switch. 8,9 Atm is first recruited to DSBs and ssDNA is later generated by resection of the DNA ends, where Atr can be assembled and activated. Thus, there exists a complex functional interaction between these two PIKKs. 10 Although several proteins have been reported to activate Atm or Atr, 11,12 the initial activation of Atm/Atr and the regulation of their activities in the process of DNA repair are poorly understood. 13,14 The c-Abl proto-oncogene encodes a non-receptor tyrosine kinase that is essential for perinatal survival in ...
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