Important molecular mechanisms in ferroptosis.

Ferroptosis is a type of cell death that is caused by the oxidation of lipids and is dependent on the presence of iron. It was first characterized by Brent R. Stockwell in 2012, and since then, research in the field of ferroptosis has rapidly expanded. The process of ferroptosis-induced cell death is genetically, biochemically, and morphologically distinct from other forms of cellular death, such as apoptosis, necroptosis, and non-programmed cell death. Extensive research has been devoted to comprehending the intricate process of ferroptosis and the various factors that contribute to it. While the majority of these studies have focused on examining the effects of lipid metabolism and mitochondria on ferroptosis, recent findings have highlighted the significant involvement of signaling pathways and associated proteins, including Nrf2, P53, and YAP/TAZ, in this process. This review provides a concise summary of the crucial signaling pathways associated with ferroptosis based on relevant studies. It also elaborates on the drugs that have been employed in recent years to treat ferroptosis-related diseases by targeting the relevant signaling pathways. The established and potential therapeutic targets for ferroptosis-related diseases, such as cancer and ischemic heart disease, are systematically addressed.

Effect and mechanism of recombinant human fibroblast growth factor 18 on osteoporosis in OVX mice.

OBJECTIVES: This study aimed to investigate the effect and the mechanism of recombinant human fibroblast growth factor 18 (rhFGF18) on postmenopausal osteoporosis. METHODS: The effect of rhFGF18 on the proliferation and apoptosis of osteoblasts and the mechanism underlying such an effect was evaluated using an oxidative stress model of the MC3T3-E1 cell line. Furthermore, ovariectomy was performed on ICR mice to imitate estrogen-deficiency postmenopausal osteoporosis. Bone metabolism and bone morphological parameters in the ovariectomized (OVX) mice were evaluated. RESULTS: The results obtained from the cell model showed that FGF18 promoted MC3T3-E1 cell proliferation by activating the extracellular signal-regulated kinase (ERK) and p38 instead of c-Jun N-terminal kinase (JNK). FGF18 also prevented cells from damage inflicted by oxidative stress via inhibition of apoptosis. After FGF18 administration, the expression level of anti-apoptotic protein Bcl-2 in the mice was upregulated, whereas those of the pro-apoptotic proteins Bax and caspase-3 were downregulated. Administering FGF18 also improved bone metabolism and bone morphological parameters in OVX mice. CONCLUSIONS: FGF18 could effectively prevent bone loss in OVX mice by enhancing osteoblastogenesis and protecting osteoblasts from oxidative stress-induced apoptosis.

Mathematical Modeling and Inference of Epidermal Growth Factor-Induced Mitogen-Activated Protein Kinase Cell Signaling Pathways.

The mitogen-activated protein kinase (MAPK) pathway is an important intracellular signaling cascade that plays a key role in various cellular processes. Understanding the regulatory mechanisms of this pathway is essential for developing effective interventions and targeted therapies for related diseases. Recent advances in single-cell proteomic technologies have provided unprecedented opportunities to investigate the heterogeneity and noise within complex, multi-signaling networks across diverse cells and cell types. Mathematical modeling has become a powerful interdisciplinary tool that bridges mathematics and experimental biology, providing valuable insights into these intricate cellular processes. In addition, statistical methods have been developed to infer pathway topologies and estimate unknown parameters within dynamic models. This review presents a comprehensive analysis of how mathematical modeling of the MAPK pathway deepens our understanding of its regulatory mechanisms, enhances the prediction of system behavior, and informs experimental research, with a particular focus on recent advances in modeling and inference using single-cell proteomic data.

Can Plant Extracts Help Prevent Hair Loss or Promote Hair Growth? A Review Comparing Their Therapeutic Efficacies, Phytochemical Components, and Modulatory Targets.

This narrative review aims to examine the therapeutic potential and mechanism of action of plant extracts in preventing and treating alopecia (baldness). We searched and selected research papers on plant extracts related to hair loss, hair growth, or hair regrowth, and comprehensively compared the therapeutic efficacies, phytochemical components, and modulatory targets of plant extracts. These studies showed that various plant extracts increased the survival and proliferation of dermal papilla cells in vitro, enhanced cell proliferation and hair growth in hair follicles ex vivo, and promoted hair growth or regrowth in animal models in vivo. The hair growth-promoting efficacy of several plant extracts was verified in clinical trials. Some phenolic compounds, terpenes and terpenoids, sulfur-containing compounds, and fatty acids were identified as active compounds contained in plant extracts. The pharmacological effects of plant extracts and their active compounds were associated with the promotion of cell survival, cell proliferation, or cell cycle progression, and the upregulation of several growth factors, such as IGF-1, VEGF, HGF, and KGF (FGF-7), leading to the induction and extension of the anagen phase in the hair cycle. Those effects were also associated with the alleviation of oxidative stress, inflammatory response, cellular senescence, or apoptosis, and the downregulation of male hormones and their receptors, preventing the entry into the telogen phase in the hair cycle. Several active plant extracts and phytochemicals stimulated the signaling pathways mediated by protein kinase B (PKB, also called AKT), extracellular signal-regulated kinases (ERK), Wingless and Int-1 (WNT), or sonic hedgehog (SHH), while suppressing other cell signaling pathways mediated by transforming growth factor (TGF)-ß or bone morphogenetic protein (BMP). Thus, well-selected plant extracts and their active compounds can have beneficial effects on hair health. It is proposed that the discovery of phytochemicals targeting the aforementioned cellular events and cell signaling pathways will facilitate the development of new targeted therapies for alopecia.

Melatonin-Assisted Cisplatin Suppresses Urinary Bladder Cancer Cell Proliferation and Growth through Inhibiting PrPC-Regulated Cell Stress and Cell Proliferation Signaling.

This study investigated whether melatonin (Mel) would promote cisplatin to suppress the proliferation and growth of bladder cancer (BC) cells by inhibiting cellular prion protein (PrPC)-mediated cell stress and cell proliferation signaling. An immunohistochemical staining of tissue arrays from BC patients demonstrated that the PrPC expression was significantly upregulated from stage I to III BC (p < 0.0001). The BC cellline of T24 was categorized into G1 (T24), G2 (T24 + Mel/100 µM), G3 (T24+cisplatin/6 µM), G4 (PrPC overexpression in T24 (i.e., PrPC-OE-T24)), G5 (PrPC-OE-T24+Mel), and G6 (PrPC-OE-T24+cisplatin). When compared with a human uroepithelial cell line (SV-HUC-1), the cellular viability/wound healing ability/migration rate were significantly increased in T24 cells (G1) and further significantly increased in PrPC-OE-T24 cells (G4); and they were suppressed in Mel (G2/G5) or cisplatin (G3/G6) treatment (all p < 0.0001). Additionally, the protein expressions of cell proliferation (PI3K/p-Akt/p-m-TOR/MMP-9/PrPC), cell cycle/mitochondrial functional integrity (cyclin-D1/clyclin-E1/ckd2/ckd4/mitochondrial-cytochrome-C/PINK1), and cell stress (RAS/c-RAF/p-MEK1/2, p-ERK1/2) markers showed a similar pattern of cell viability among the groups (all p < 0.001). After the BC cell line of UMUC3 was implanted into nude mouse backs, by day 28 mthe BC weight/volume and the cellular levels of PrPC/MMP-2/MMP-9 were significantly, gradually reduced from groups one to four (all p < 0.0001). The protein expressions of cell proliferation (PI3K/p-Akt/p-m-TOR/MMP-9/PrPC), cell cycle/mitophagy (cyclin-D1/clyclin-E1/ckd2/ckd4/PINK1), and cell stress (RAS/c-RAF/p-MEK1,2/p-ERK1,2) signaling were significantly, progressively reduced from groups one to four, whereas the protein expressions of apoptotic (Mit-Bax/cleaved-caspase-3/cleaved-PARP) and oxidative stress/mitochondrial damaged (NOX-1/NOX-2/cytosolic-cytochrome-C/p-DRP1) markers expressed an opposite pattern of cell proliferation signaling among the groups (all p < 0.0001). Mel-cisplatin suppressed BC cell growth/proliferation via inhibiting the PrPC in upregulating the cell proliferation/cell stress/cell cycle signaling.

Multiple proliferation signaling pathways are modulated by octacalcium phosphate in osteoblasts.

Octacalcium phosphate (OCP), a type of bioactive ceramics, may be associated with dentine, tooth apatite, and especially bone generation, and promotes wound healing after fracture. Recently, commercial bone grafting products containing a large amount of OCP material have been released because OCP can be synthesized in large quantities. It is reported to increase cell proliferation, but the interaction between OCP and cell signaling pathways is still unclear. In this study, first, we demonstrated OCP mediated cell signaling pathways with only purified OCP materials. OCP regulated P38, JNK (c-Jun N-terminal kinase), Src, and AKT (protein kinase B) signaling pathways. OCP crystals appeared in the characteristic ribbon shape but varied by several tens of micrometers in size. The X-ray diffraction pattern was the same as previously reported. We studied two concentrations of OCP (10 mg/ml and 20 mg/ml) to understand whether the effect of OCP on cell signaling pathways is dose dependent. We confirmed that OCP treatment affected cell proliferation and alkaline phosphatase and disrupted Src phosphorylation but did not change the total protein level. P38 phosphorylation was activated with OCP treatment and inhibited by SB203580, but P38 total protein level did not change. OCP inhibited JNK phosphorylation signaling, whereas PD98509 inhibited JNK phosphorylation with or without OCP. Interestingly, the AKT total level decreased after OCP treatment, but AKT phosphorylation increased considerably. Our results demonstrate that OCP materials modulate cell signaling pathways and increase cell proliferation.

Aclonifen induces bovine mammary gland epithelial cell death by disrupting calcium homeostasis and inducing ROS production.

Herbicides play key roles in agriculture. Aclonifen is a diphenyl ether herbicide that is widely used for sunflower, potato, corn, and wheat crops. Since it has a long half-life, it is considered persistent and can easily accumulate in the environment. Therefore, livestock and humans are at risk of exposure to aclonifen. Importantly, aclonifen is toxic to several mammals such as rats, mice, and dogs. However, the toxicity of aclonifen in cattle remains unclear. Therefore, we sought to investigate its toxicity in cattle using bovine mammary gland epithelial cells (MAC-T). We found that aclonifen induces sub-G1 phase arrest and represses MAC-T proliferation. In addition, aclonifen caused mitochondrial dysfunction, as evidenced by excessive ROS production and loss of mitochondrial membrane potential. Furthermore, cytosolic and mitochondrial calcium homeostases were disrupted after aclonifen treatment. Moreover, aclonifen treatment caused alterations in the PI3K/AKT and MAPK signaling pathways, which are involved in the regulation of cell survival and death. In conclusion, aclonifen causes MAC-T cell death through mitochondrial dysfunction and the collapse of calcium homeostasis.

Pendimethalin exposure induces bovine mammary epithelial cell death through excessive ROS production and alterations in the PI3K and MAPK signaling pathways.

Herbicides are chemicals that have been established to have adverse impacts. However, they are still widely used in agriculture. Pendimethalin (PDM) is an herbicide that is widely used in many countries to control annual grasses. The possibility of livestock being exposed to PDM is relatively high, considering the half-life of PDM and its residues in water, soil and crops. However, the toxicity of PDM in cattle, especially in the mammary glands, has not been reported. Therefore, we investigated whether PDM has toxic effects in the mammary epithelial cells (MAC-T) of cattle. MAC-T cells were treated with various doses (0, 2.5, 5 and 10 µM) of PDM. We found that PDM affected cell viability and cell proliferation and causes cell cycle arrest. Furthermore, PDM triggered cell apoptosis, induced excessive ROS production and mitochondrial membrane potential (MMP) loss, and disrupted calcium homeostasis. In addition, PDM altered the activation of proteins associated with the endoplasmic reticulum (ER) stress response and modified PI3K and MAPK signaling cascades. In conclusion, our current study unveiled the mechanism of PDM in MAC-T cells and we suggest that PDM might be harmful to the mammary gland system of cattle, possibly affecting milk production.

Flavones: Six Selected Flavones and Their Related Signaling Pathways That Induce Apoptosis in Cancer.

Cancer is a horrific disease that, to date, has no cure. It is caused by various factors and takes many lives. Apoptosis is a programmed cell death mechanism and if it does not function correctly in cancer cells, it can lead to severe disease. There are various signaling pathways for regulating apoptosis in cancer cells. Flavonoids are non-artificial natural bioactive compounds that are gaining attention as being capable of for inducing apoptosis in cancer cells. Among these, in this study, we focus on flavones. Flavones are a subclass of the numerous available flavonoids and possess several bioactive functions. Some of the most reported and well-known critical flavones, namely apigenin, acacetin, baicalein, luteolin, tangeretin, and wogonin, are discussed in depth in this review. Our main aim is to investigate the effects of the selected flavones on apoptosis and cell signaling pathways that contribute to death due to various types of cancers.

[Therapeutic effect of Baimai Ointment on peripheral sensitization of chronic inflammatory pain in mice].

Chronic inflammatory pain is mainly manifested by peripheral sensitization. Baimai Ointment(BMO), a classical Tibetan medicine for external use, has good clinical efficacy in the treatment of chronic inflammatory pain, while its pharmacodynamics and mechanism for relieving peripheral sensitization remain unclear. This study established an animal model of chronic inflammatory pain induced by complete Freund's adjuvant to explore the mechanism of BMO in the treatment of chronic inflammatory pain by behavioral test, side effect assessment, network analysis, and experimental verification. The pharmacodynamics experiment showed that BMO increased the thresholds of mechanical pain sensitivity and thermal radiation pain sensitivity of chronic inflammatory pain mice in a dose-dependent manner, and had inhibitory effect on foot swelling, inflammatory mediator, and the expression of transient receptor potential vanilloid-1(TRPV1) and transient receptor potential A1(TRPA1). The results of body weight monitoring, pain sensitivity threshold detection in normal mice, rotarod performance test, and forced swimming test showed that BMO had no obvious toxic or side effect. The network analysis of 51 candidate active molecules selected according to the efficacy of BMO, content of main components, and ADME parameters showed that the inhibitory effect of BMO on chronic inflammatory pain was associated with the core regulatory elements of tumor necrosis factor(TNF) and T cell receptor signaling pathways. BMO down-regulated the protein levels of mitogen-activated protein kinase 14(MAPK14), MAPK1, and prostaglandin-endoperoxide synthase 2(PTGS2), and up-regulated the phosphorylation le-vel of glycogen synthase kinase 3 beta(GSK3 B) in the plantar tissue of mice. In conclusion, BMO can effectively relieve peripheral sensitization of chronic inflammatory pain without inducing tolerance and obvious toxic and side effects. The relevant mechanism may be related to the regulation of BMO on core regulatory elements of TNF and T cell receptor signaling pathways in surrounding tissues.

Cancer chemopreventive role of fisetin: Regulation of cell signaling pathways in different cancers.

It is becoming progressively more understandable that pharmaceutical targeting of drug-resistant cancers is challenging because of intra- and inter-tumor heterogeneity. Interestingly, naturally derived bioactive compounds have unique ability to modulate wide-ranging deregulated oncogenic cell signaling pathways. In this review, we have focused on the available evidence related to regulation of PI3K/AKT/mTOR, Wnt/ß-catenin, NF-κB and TRAIL/TRAIL-R by fisetin in different cancers. Fisetin has also been shown to inhibit the metastatic spread of cancer cells in tumor-bearing mice. We have also summarized how fisetin regulated autophagy in different cancers. In addition, this review also covers fisetin-mediated regulation of VEGF/VEGFR, EGFR, necroptosis and Hippo pathway. Fisetin has entered into clinical trials particularly in context of COVID19-associated inflammations. Furthermore, fisetin mediated effects are also being tested in clinical trials with reference to osteoarthritis and senescence. These developments will surely pave the way for full-fledge and well-designed clinical trials of fisetin in different cancers. However, we still have to comprehensively analyze and fully unlock pharmacological potential of fisetin against different oncogenic signaling cascades and non-coding RNAs. Fisetin has remarkable potential as chemopreventive agent and future studies must converge on the identification of additional regulatory roles of fisetin for inhibition and prevention of cancers.

[Research progress of effect of berberine in treatment of ulcerative colitis based on cell signaling pathway].

Berberine is the main extract of Coptis chinensis, and its anti-inflammatory, antioxidant, antibacterial and immunomodulatory effects have been confirmed by modern studies. Ulcerative colitis(UC) is a chronic, idiopathic inflammatory bowel disease with unknown etiology. Its causes involve genetics, intestinal microecology and mucosal immune system disorders. In this paper, literatures on relevant pathways and mechanism of berberine on ulcerative colitis in recent years were consulted and summarized to provide me-thods and ideas for developing berberine in the treatment of UC and exploring the mechanisms. The results showed that berberine protects the intestinal mucosal barrier, restores the body's normal immune response, and improves oxidative stress by regulating multiple signaling pathways, such as JAK-STAT, NK-κB, PI3 K-AKT, MAPK, Nrf2, ERS, and MLCK-MLC, so as to treat UC.

Transcriptomic insight into salinomycin mechanisms in breast cancer cell lines: synergistic effects with dasatinib and induction of estrogen receptor ß.

BACKGROUND: Tumors are heterogeneous in nature, composed of different cell populations with various mutations and/or phenotypes. Using a single drug to encounter cancer progression is generally ineffective. To improve the treatment outcome, multiple drugs of distinctive mechanisms but complementary anticancer activities (combination therapy) are often used to enhance antitumor efficacy and minimize the risk of acquiring drug resistance. We report here the synergistic effects of salinomycin (a polyether antibiotic) and dasatinib (a Src kinase inhibitor). METHODS: Functionally, both drugs induce cell cycle arrest, intracellular reactive oxygen species (iROS) production, and apoptosis. We rationalized that an overlapping of the drug activities should offer an enhanced anticancer effect, either through vertical inhibition of the Src-STAT3 axis or horizontal suppression of multiple pathways. We determined the toxicity induced by the drug combination and studied the kinetics of iROS production by fluorescence imaging and flow cytometry. Using genomic and proteomic techniques, including RNA-sequencing (RNA-seq), reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and Western Blot, we subsequently identified the responsible pathways that contributed to the synergistic effects of the drug combination. RESULTS: Compared to either drug alone, the drug combination showed enhanced potency against MDA-MB-468, MDA-MB-231, and MCF-7 human breast cancer (BC) cell lines and tumor spheroids. The drug combination induces both iROS generation and apoptosis in a time-dependent manner, following a 2-step kinetic profile. RNA-seq data revealed that the drug combination exhibited synergism through horizontal suppression of multiple pathways, possibly through a promotion of cell cycle arrest at the G1/S phase via the estrogen-mediated S-phase entry pathway, and partially via the BRCA1 and DNA damage response pathway. CONCLUSION: Transcriptomic analyses revealed for the first time, that the estrogen-mediated S-phase entry pathway partially contributed to the synergistic effect of the drug combination. More importantly, our studies led to the discoveries of new potential therapeutic targets, such as E2F2, as well as a novel drug-induced targeting of estrogen receptor ß (ESR2) approach for triple-negative breast cancer treatment, currently lacking of targeted therapies.

Ivermectin-induced programmed cell death and disruption of mitochondrial membrane potential in bovine mammary gland epithelial cells.

Ivermectin (IVM) is a commercially well-known antiparasitic agent derived from the natural fermentation product avermectin. Originally used as a veterinary drug, IVM has been studied for its pharmacokinetic advantages, such as anticancer, antimigration, and antiproliferative effects, using several cell types. In the present study, we verified that IVM suppressed bovine mammary gland epithelial cell proliferation and induced the arrest of the cell cycle from the sub-G1 to the G2/M phase in these cells. Due to IVM treatment, the homeostasis of calcium ions, which play a crucial role in intracellular metabolism, deteriorated, leading to the loss of the mitochondrial membrane potential (MMP). To underpin these results, further studies using inhibitors of Ca2+ signaling were performed; combination treatment with IVM and these factors, including 2-APB, BAPTA-AM, or ruthenium red, inhibited the IVM-induced MMP disruption. Furthermore, following IVM treatment, the relationships among various cell signaling mediators were altered, and the balance between diverse cellular processes associated with cell survival or death was disturbed. In conclusion, we assessed the anti-survival effects of IVM on mammary gland epithelial cells; IVM may impede normal lactation in dairy cows.

The Identification of Anthocyanins from Padus racemosa and Its Protective Effects on H2 O2 -Induced INS-1 Cells Damage and STZ-Induced Diabetes Mice.

Oxidative damage in cells induced by reactive oxygen species (ROS) is a main factor in diabetes mellitus diseases progression. The composition of anthocyanins from Padus racemosa (APR) and the protective effects of APR on H2 O2 -induced rat insulinoma (INS-1) cells damage and streptozocin (STZ)-induced diabetes mice were investigated in this study. The main components of APR were cyanidin-cyanidin glucosyl-rutinoside, cyanidin-cyanidin xylosyl-rutinoside, cyanidin-xylosyl-glucoside and cyanidin-rutinoside, which were determined by liquid chromatography-mass spectrometry (LC/MS). APR could scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical and superoxide radical in vitro. ROS level was decreased and the cell viability was increased in INS-1 cells after treated with APR. Cell apoptosis induced by H2 O2 in INS-1 cells was decreased after incubation with APR. APR could decrease the phosphorylation of p38 and the nuclear translocation of p65, which indicated that APR could inhibit the activation of p38 Mitogen-activated protein kinase (MAPK) and Nuclear factor kappa B (NF-κB) cell signaling pathways. Meanwhile, APR could effectively reduce the blood glucose and blood lipid in STZ-induced diabetic mice. These results suggested that APR might be a potential agent for diabetes mellitus diseases treatment.

Regulation mechanism of silkworm pupa oil PUFAs on cholesterol metabolism in hepatic cell L-02.

BACKGROUND: Silkworm pupa oil polyunsaturated fatty acid (SPO PUFA) has been confirmed to have a cholesterol-lowering function. METHODS AND RESULTS: The effect of SPO PUFA and its main component, α-linolenic acid (ALA), on the metabolism of cholesterol and its regulation was investigated. The model of lipid denatured cells were constructed to carry out lipid accumulation, cholesterol metabolism and transformation. Real-time PCR and western blots were also used to analyze the expression levels of related genes and proteins to investigate the cholesterol efflux regulation mechanism. The data indicated that SPO PUFA and ALA dose-dependently decreased intracellular total cholesterol (TC) and enhanced total bile acid (TBA). They could also promote cholesterol removal by enhancing bile acid secretion and by upregulating genes LXRα, PPARγ, ABCA1, ABCG1, and CYP7A1, which were regulated by LXRα/PPARγ-ABCA1/ABCG1-CYP7A1 nuclear receptor signal pathways. CONCLUSIONS: This study is of great significance in maintaining the balance of cholesterol and lipid metabolism, and in reducing the risk of steatohepatitis. © 2019 Society of Chemical Industry.

Purification of recombinant human fibroblast growth factor 13 in E. coli and its molecular mechanism of mitogenesis.

Fibroblast growth factor (FGF) 13, a member of the FGF11 subfamily, is a kind of intracrine protein similar to other family members including FGF11, FGF12, and FGF14. Unlike classical FGF, FGF13 exerts its bioactivities independent of fibroblast growth factor receptors (FGFRs). However, the effect of exogenous administration of FGF13 still remains further investigated. In the present study, we established an Escherichia coli expression system for the large-scale production of FGF13 and then obtained two isoform proteins including recombinant human FGF13A (rhFGF13A) and rhFGF13B with a purity greater than 90% by column chromatography, respectively. Otherwise, soluble analysis indicated that both rhFGF13A and rhFGF13B expressed in E. coli BL21 (DE3) pLysS were soluble. Furthermore, cellular-based experiments demonstrated that rhFGF13A, rather than rhFGF13B, could promote the proliferation of NIH3T3 cells in the presence of heparin. Mechanistically, the mitogenic effect of FGF13 was mediated by activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), but not p38. Moreover, blockage of FGFRs also significantly attenuated the mitogenic effects of rhFGF13A, implying that FGFRs are still related to FGF13. Thus, our research shows that exogenous FGF13 can act as secreted FGF to participate in cell signal transmission and heparin is still required as an ancillary cofactor for the mitogenic effects of FGF13, which may help people to discover more potential functions of FGF13 in cell life activities.

Cytosolic Acidification Is the First Transduction Signal of Lactoferrin-induced Regulated Cell Death Pathway.

In yeast, we reported the critical role of K+-efflux for the progress of the regulated cell death (RCD) induced by human lactoferrin (hLf), an antimicrobial protein of the innate immune system that blocks Pma1p H+-ATPase. In the present study, the K+ channel Tok1p was identified as the K+ channel-mediating K+-efflux, as indicated by the protective effect of extracellular K+ (30 mM), K+-channel blockers, and the greater hLf-resistance of TOK1-disrupted strains. K+-depletion was necessary but not sufficient to induce RCD as inferred from the effects of valinomycin, NH4Cl or nigericin which released a percentage of K+ similar to that released by lactoferrin without affecting cell viability. Cytosolic pH of hLf-treated cells decreased transiently (0.3 pH units) and its inhibition prevented the RCD process, indicating that cytosolic acidification was a necessary and sufficient triggering signal. The blocking effect of lactoferrin on Pma1p H+-ATPase caused a transitory decrease of cytosolic pH, and the subsequent membrane depolarization activated the voltage-gated K+ channel, Tok1p, allowing an electrogenic K+-efflux. These ionic events, cytosolic accumulation of H+ followed by K+-efflux, constituted the initiating signals of this mitochondria-mediated cell death. These findings suggest, for the first time, the existence of an ionic signaling pathway in RCD.

Structure, clustering and functional insights of repeats configurations in the upstream promoter region of the human coding genes.

BACKGROUND: Repetitive DNA sequences (Repeats) are significant regions in the human genome that have a specific genomic distribution, structure, and several binding sites for genome architecture and function. In consequence, the possible configurations of Repeats in specific and dynamic regions like the gene promoters could define footprints for molecular mechanisms, pathways, and cell function beyond their density in the genome. Here we explored the distribution of Repeats in the upstream promoter region of the human coding genes with the aim to identify specific configurations, clusters and functional meaning of those elements. Our method includes structural descriptions, hierarchical clustering, pathway association, and functional enrichment analysis. RESULTS: We report here several configurations of Repeats in the upstream promoter region (UPR), which define 2729 patterns for the 80% of the human coding genes. There are 47 types of Repeats in these configurations, where the most frequent were Alu, Low_complexity, MIR, Simple_repeat, LINE/L2, LINE/L1, hAT-Charlie, and ERV1. The distribution, length, and the high frequency of Repeats in the UPR defines several patterns and clusters, where the minimum frequency of configuration among Repeats was higher than 0.7. We found those clusters associated with cellular pathways and ontologies; thus, it was plausible to determine groups of Repeats to specific functional insights, for example, pathways for Genetic Information Processing or Metabolism shows particular groups of Repeats with specific configurations. CONCLUSION: Based on these findings, we propose that specific configurations of repetitive elements describe frequent patterns in the upstream promoter for sets of human coding genes, which those correlated to specific and essential cell pathways and functions.

Emerging Role of MicroRNAs in mTOR Signaling.

Mechanistic target of rapamycin (mTOR) is a conserved serine/threonine kinase that plays a critical role in the control of cellular growth and metabolism. Hyperactivation of mTOR pathway is common in human cancers, driving uncontrolled proliferation. MicroRNA (miRNA) is a class of short noncoding RNAs that regulate the expression of a wide variety of genes. Deregulation of miRNAs is a hallmark of cancer. Recent studies have revealed interplays between miRNAs and the mTOR pathway during cancer development. Such interactions appear to provide a fine-tuning of various cellular functions and contribute qualitatively to the behavior of cancer. Here we provide an overview of current knowledge regarding the reciprocal relationship between miRNAs and mTOR pathway: regulation of mTOR signaling by miRNAs and control of miRNA biogenesis by mTOR. Further research in this area may prove important for the diagnosis and therapy of human cancer.