Human p8 is a HMG-I/Y-like protein with DNA binding activity enhanced by phosphorylation

Microgravity triggers ferroptosis and accelerates senescence in the MG-63 cell model of osteoblastic cells

In space, cells sustain strong modifications of their mechanical environment. Mechanosensitive molecules at the cell membrane regulate mechanotransduction pathways that induce adaptive responses through the regulation of gene expression, post-translational modifications, protein interactions or intracellular trafficking, among others. In the current study, human osteoblastic cells were cultured on the ISS in microgravity and at 1 g in a centrifuge, as onboard controls. RNAseq analyses showed that microgravity inhibits cell proliferation and DNA repair, stimulates inflammatory pathways and induces ferroptosis and senescence, two pathways related to ageing. Morphological hallmarks of senescence, such as reduced nuclear size and changes in chromatin architecture, proliferation marker distribution, tubulin acetylation and lysosomal transport were identified by immunofluorescence microscopy, reinforcing the hypothesis of induction of cell senescence in microgravity during space flight. These processes could be attributed, at least in part, to the regulation of YAP1 and its downstream effectors NUPR1 and CKAP2L.

Anti-HERV-K Drugs and Vaccines, Possible Therapies against Tumors

The footprint of human endogenous retroviruses (HERV), specifically HERV-K, has been found in malignancies, such as melanoma, teratocarcinoma, osteosarcoma, breast cancer, lymphoma, and ovary and prostate cancers. HERV-K is characterized as the most biologically active HERV due to possession of open reading frames (ORF) for all Gag, Pol, and Env genes, which enables it to be more infective and obstructive towards specific cell lines and other exogenous viruses, respectively. Some factors might contribute to carcinogenicity and at least one of them has been recognized in various tumors, including overexpression/methylation of long interspersed nuclear element 1 (LINE-1), HERV-K Gag, and Env genes themselves plus their transcripts and protein products, and HERV-K reverse transcriptase (RT). Therapies effective for HERV-K-associated tumors mostly target invasive autoimmune responses or growth of tumors through suppression of HERV-K Gag or Env protein and RT. To design new therapeutic options, more studies are needed to better understand whether HERV-K and its products (Gag/Env transcripts and HERV-K proteins/RT) are the initiators of tumor formation or just the disorder’s developers. Accordingly, this review aims to present evidence that highlights the association between HERV-K and tumorigenicity and introduces some of the available or potential therapies against HERV-K-induced tumors.

Nupr1 deficiency downregulates HtrA1, enhances SMAD1 signaling, and suppresses age-related bone loss in male mice

Nuclear protein 1 (NUPR1) is a stress-induced protein activated by various stresses, such as inflammation and oxidative stress. We previously reported that Nupr1 deficiency increased bone volume by enhancing bone formation in 11-week-old mice. Analysis of differentially expressed genes between wild-type (WT) and Nupr1-knockout (Nupr1-KO) osteocytes revealed that high temperature requirement A 1 (HTRA1), a serine protease implicated in osteogenesis and transforming growth factor-β signaling was markedly downregulated in Nupr1-KO osteocytes. Nupr1 deficiency also markedly reduced HtrA1 expression, but enhanced SMAD1 signaling in in vitro-cultured primary osteoblasts. In contrast, Nupr1 overexpression enhanced HtrA1 expression in osteoblasts, suggesting that Nupr1 regulates HtrA1 expression, thereby suppressing osteoblastogenesis. Since HtrA1 is also involved in cellular senescence and age-related diseases, we analyzed aging-related bone loss in Nupr1-KO mice. Significant spine trabecular bone loss was noted in WT male and female mice during 6-19 months of age, whereas aging-related trabecular bone loss was attenuated, especially in Nupr1-KO male mice. Moreover, cellular senescence-related markers were upregulated in the osteocytes of 6-19-month-old WT male mice but markedly downregulated in the osteocytes of 19-month-old Nupr1-KO male mice. Oxidative stress-induced cellular senescence stimulated Nupr1 and HtrA1 expression in in vitro-cultured primary osteoblasts, and Nupr1 overexpression enhanced p16^ink4a expression in osteoblasts. Finally, NUPR1 expression in osteocytes isolated from the bones of patients with osteoarthritis was correlated with age. Collectively, these results indicate that Nupr1 regulates HtrA1-mediated osteoblast differentiation and senescence. Our findings unveil a novel Nupr1/HtrA1 axis, which may play pivotal roles in bone formation and age-related bone loss.

Intrinsically Disordered Chromatin Protein NUPR1 Binds to the Enzyme PADI4

The nuclear protein 1 (NUPR1) is an intrinsically disordered protein involved in stress-mediated cellular conditions. Its paralogue nuclear protein 1-like (NUPR1L) is p53-regulated, and its expression down-regulates that of the NUPR1 gene. Peptidyl-arginine deiminase 4 (PADI4) is an isoform of a family of enzymes catalyzing arginine to citrulline conversion; it is also involved in stress-mediated cellular conditions. We characterized the interaction between NUPR1 and PADI4 in vitro, in silico, and in cellulo. The interaction of NUPR1 and PADI4 occurred with a dissociation constant of 18 ± 6 μM. The binding region of NUPR1, mapped by NMR, was a hydrophobic polypeptide patch surrounding the key residue Ala33, as pinpointed by: (i) computational results; and, (ii) site-directed mutagenesis of residues of NUPR1. The association between PADI4 and wild-type NUPR1 was also assessed in cellulo by using proximity ligation assays (PLAs) and immunofluorescence (IF), and it occurred mainly in the nucleus. Moreover, binding between NUPR1L and PADI4 also occurred in vitro with an affinity similar to that of NUPR1. Molecular modelling provided information on the binding hot spot for PADI4. This is an example of a disordered partner of PADI4, whereas its other known interacting proteins are well-folded. Altogether, our results suggest that the NUPR1/PADI4 complex could have crucial functions in modulating DNA-repair, favoring metastasis, or facilitating citrullination of other proteins.

NUPR1 imparts oncogenic potential in bladder cancer

BACKGROUND

NUPR1, or p8, is a small chromatin protein that plays a central role in the resistance to treatment and progression of cancer. Nevertheless, the molecular mechanism of NUPR1 in bladder cancer (BLCA) remains unclear.

METHODS

We used online databases and immunohistochemistry (IHC) to explore the expression of NUPR1 in BLCA tissues and controls. Lentivirus-mediated small interfering ribonucleic acid (siRNA) was used to knockdown the expression of NUPR1 in two human BLCA cell lines. We used an in vivo experiment to investigate the effect of NUPR1 knockdown on the growth of BLCA. Moreover, an in silico analysis was conducted to assess the differential expression profile after NUPR1 interference. The CIBERSORT algorithm was utilized to evaluate the effects of tumor-infiltrating immune cells among BLCA patients.

RESULTS

The expression of NUPR1 in BLCA tissues was significantly higher than in the control. NUPR1 expression was also positively correlated with the stage of BLCA. After lentivirus-mediated interference, the expression of NUPR1 was significantly down-regulated in BLCA cell lines. The cell cycle was blocked in G1 phase and the cell proportion of S phase was decreased in both two cell lines. Moreover, in vivo experiment revealed that the tumor growth of BLCA can be delayed by inhibiting the expression of NUPR1. Both in silico analysis and functional experiments revealed that NUPR1 was correlated with epithelial-mesenchymal transition (EMT). We also revealed that macrophages were the most related immune cells associated with the expression of NUPR1 in BLCA.

CONCLUSIONS

This study suggests that NUPR1 plays a carcinogenic role in BLCA. NUPR1 lentivirus-mediated interference could interfere with cycle progression of the BLCA cell, resulting in cell cycle arrest in the G1-phase. The carcinogenic effect of NUPR1 in BLCA is likely achieved through EMT. NUPR1 is correlated with the M0-type macrophage markers CD68 and CD11b-integrin.

The role of NUPR1 in response to stress and cancer development

Stress contributes to the development of many human diseases, including cancer. Based on the source of stress, it can be divided into external stress, such as environmental carcinogens, chemicals, and radiation, and internal stress, like endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Nuclear Protein 1 (NUPR1, p8 or Com-1) is a small, highly basic transcriptional regulator that participates in regulating a variety of cellular processes including DNA repair, ER stress, oxidative stress response, cell cycle, autophagy, apoptosis, ferroptosis and chromatin remodeling. A large number of studies have reported that NUPR1 expression can be stimulated rapidly in response to various stresses. Thus, NUPR1 is also known as a stress-response gene. Since the role of NUPR1 in breast cancer was identified in 1999, an increasing number of studies sought to reveal its function in cancer. High expression of NUPR1 has been identified in oral squamous cell carcinoma, breast cancer, lung cancer, multiple myeloma, liver cancer and renal cancer. In this review, we summarize current studies of NUPR1 in response to multiple external stressors and internal stressors, and its role in mediating stressors to cause different cell signaling responses. In addition, this review discusses the function of NUPR1 in carcinogenesis, tumorigenesis, metastasis, and cancer therapy. Thus, this review gives a comprehensive insight into the role of NUPR1 in mediating signals from stress to different cell responses, and this process plays a role in the development of cancer.

Design of Inhibitors of the Intrinsically Disordered Protein NUPR1: Balance between Drug Affinity and Target Function

Intrinsically disordered proteins (IDPs) are emerging as attractive drug targets by virtue of their physiological ubiquity and their prevalence in various diseases, including cancer. NUPR1 is an IDP that localizes throughout the whole cell, and is involved in the development and progression of several tumors. We have previously repurposed trifluoperazine (TFP) as a drug targeting NUPR1 and, by using a ligand-based approach, designed the drug ZZW-115 starting from the TFP scaffold. Such derivative compound hinders the development of pancreatic ductal adenocarcinoma (PDAC) in mice, by hampering nuclear translocation of NUPR1. Aiming to further improve the activity of ZZW-115, here we have used an indirect drug design approach to modify its chemical features, by changing the substituent attached to the piperazine ring. As a result, we have synthesized a series of compounds based on the same chemical scaffold. Isothermal titration calorimetry (ITC) showed that, with the exception of the compound preserving the same chemical moiety at the end of the alkyl chain as ZZW-115, an increase of the length by a single methylene group (i.e., ethyl to propyl) significantly decreased the affinity towards NUPR1 measured in vitro, whereas maintaining the same length of the alkyl chain and adding heterocycles favored the binding affinity. However, small improvements of the compound affinity towards NUPR1, as measured by ITC, did not result in a corresponding improvement in their inhibitory properties and in cellulo functions, as proved by measuring three different biological effects: hindrance of the nuclear translocation of the protein, sensitization of cells against DNA damage mediated by NUPR1, and prevention of cancer cell growth. Our findings suggest that a delicate compromise between favoring ligand affinity and controlling protein function may be required to successfully design drugs against NUPR1, and likely other IDPs.

Crowding Effects on the Structure and Dynamics of the Intrinsically Disordered Nuclear Chromatin Protein NUPR1

The intracellular environment is crowded with macromolecules, including sugars, proteins and nucleic acids. In the cytoplasm, crowding effects are capable of excluding up to 40% of the volume available to any macromolecule when compared to dilute conditions. NUPR1 is an intrinsically disordered protein (IDP) involved in cell-cycle regulation, stress-cell response, apoptosis processes, DNA binding and repair, chromatin remodeling and transcription. Simulations of molecular crowding predict that IDPs can adopt compact states, as well as more extended conformations under crowding conditions. In this work, we analyzed the conformation and dynamics of NUPR1 in the presence of two synthetic polymers, Ficoll-70 and Dextran-40, which mimic crowding effects in the cells, at two different concentrations (50 and 150 mg/ml). The study was carried out by using a multi-spectroscopic approach, including: site-directed spin labelling electron paramagnetic resonance spectroscopy (SDSL-EPR), nuclear magnetic resonance spectroscopy (NMR), circular dichroism (CD), small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). SDSL-EPR spectra of two spin-labelled mutants indicate that there was binding with the crowders and that the local dynamics of the C and N termini of NUPR1 were partially affected by the crowders. However, the overall disordered nature of NUPR1 did not change substantially in the presence of the crowders, as shown by circular dichroism CD and NMR, and further confirmed by EPR. The changes in the dynamics of the paramagnetic probes appear to be related to preferred local conformations and thus crowding agents partially affect some specific regions, further pinpointing that NUPR1 flexibility has a key physiological role in its activity.

Intrinsically disordered protein NUPR1 binds to the armadillo-repeat domain of Plakophilin 1

Plakophilin 1 (PKP1), a member of the armadillo repeat family of proteins, is a scaffold component of desmosomes, which are key structural components for cell-cell adhesion. However, PKP1 can be also found in the nucleus of several cells. NUPR1 is an intrinsically disordered protein (IDP) that localizes throughout the whole cell, and intervenes in the development and progression of several cancers. In this work, we studied the binding between PKP1 and NUPR1 by using several in vitro biophysical techniques and in cellulo approaches. The interaction occurred with an affinity in the low micromolar range (~10 μM), and involved the participation of at least one of the tryptophan residues of PKP1 (as shown by fluorescence and molecular docking). The binding region of NUPR1, mapped by NMR and molecular modelling, was a polypeptide patch at the 30s region of its sequence. The association between PKP1 and NUPR1 also occurred in cellulo and was localized in the nucleus, as tested by protein ligation assays (PLAs). We hypothesize that NUPR1 plays an active role in carcinogenesis modulating the function of PKP1.

Cannabinoids in Medicine: Cancer, Immunity, and Microbial Diseases

Recently, there has been a growing interest in the medical applications of Cannabis plants. They owe their unique properties to a group of secondary metabolites known as phytocannabinoids, which are specific for this genus. Phytocannabinoids, and cannabinoids generally, can interact with cannabinoid receptors being part of the endocannabinoid system present in animals. Over the years a growing body of scientific evidence has been gathered, suggesting that these compounds have therapeutic potential. In this article, we review the classification of cannabinoids, the molecular mechanisms of their interaction with animal cells as well as their potential application in the treatment of human diseases. Specifically, we focus on the research concerning the anticancer potential of cannabinoids in preclinical studies, their possible use in cancer treatment and palliative medicine, as well as their influence on the immune system. We also discuss their potential as therapeutic agents in infectious, autoimmune, and gastrointestinal inflammatory diseases. We postulate that the currently ongoing and future clinical trials should be accompanied by research focused on the cellular and molecular response to cannabinoids and Cannabis extracts, which will ultimately allow us to fully understand the mechanism, potency, and safety profile of cannabinoids as single agents and as complementary drugs.

Targeting NUPR1 for Cancer Treatment: A Risky Endeavor

NUPR1 is a transcription factor that has attracted great attention because of its various roles in cancer. Several studies were carried out to determine its molecular targets and mechanism of action to develop novel therapies against cancer. Here, we shed light on the role of NUPR1 in different types of cancer. NUPR1 regulates a complex network of pathways that may be affected by its silencing, which can cause varying effects. Its role in some types of cancer has been reported but remains incompletely understood, whereas its roles in other types of cancers have not been reported yet. Therefore, targeting NUPR1 for cancer treatment remains challenging and risky.

The Paralogue of the Intrinsically Disordered Nuclear Protein 1 Has a Nuclear Localization Sequence that Binds to Human Importin α3

Numerous carrier proteins intervene in protein transport from the cytoplasm to the nucleus in eukaryotic cells. One of those is importin α, with several human isoforms; among them, importin α3 (Impα3) features a particularly high flexibility. The protein NUPR1L is an intrinsically disordered protein (IDP), evolved as a paralogue of nuclear protein 1 (NUPR1), which is involved in chromatin remodeling and DNA repair. It is predicted that NUPR1L has a nuclear localization sequence (NLS) from residues Arg51 to Gln74, in order to allow for nuclear translocation. We studied in this work the ability of intact NUPR1L to bind Impα3 and its depleted species, ∆Impα3, without the importin binding domain (IBB), using fluorescence, isothermal titration calorimetry (ITC), circular dichroism (CD), nuclear magnetic resonance (NMR), and molecular docking techniques. Furthermore, the binding of the peptide matching the isolated NLS region of NUPR1L (NLS-NUPR1L) was also studied using the same methods. Our results show that NUPR1L was bound to Imp α3 with a low micromolar affinity (~5 μM). Furthermore, a similar affinity value was observed for the binding of NLS-NUPR1L. These findings indicate that the NLS region, which was unfolded in isolation in solution, was essentially responsible for the binding of NUPR1L to both importin species. This result was also confirmed by our in silico modeling. The binding reaction of NLS-NUPR1L to ∆Impα3 showed a larger affinity (i.e., lower dissociation constant) compared with that of Impα3, confirming that the IBB could act as an auto-inhibition region of Impα3. Taken together, our findings pinpoint the theoretical predictions of the NLS region in NUPR1L and, more importantly, suggest that this IDP relies on an importin for its nuclear translocation.

A Phosphorylation-Induced Switch in the Nuclear Localization Sequence of the Intrinsically Disordered NUPR1 Hampers Binding to Importin

Several carrier proteins are involved in protein transport from the cytoplasm to the nucleus in eukaryotic cells. One of those is importin α, of which there are several human isoforms; among them, importin α3 (Impα3) has a high flexibility. The protein NUPR1, a nuclear protein involved in the cell-stress response and cell cycle regulation, is an intrinsically disordered protein (IDP) that has a nuclear localization sequence (NLS) to allow for nuclear translocation. NUPR1 does localize through the whole cell. In this work, we studied the affinity of the isolated wild-type NLS region (residues 54–74) of NUPR1 towards Impα3 and several mutants of the NLS region by using several biophysical techniques and molecular docking approaches. The NLS region of NUPR1 interacted with Impα3, opening the way to model the nuclear translocation of disordered proteins. All the isolated NLS peptides were disordered. They bound to Impα3 with low micromolar affinity (1.7–27 μM). Binding was hampered by removal of either Lys65 or Lys69 residues, indicating that positive charges were important; furthermore, binding decreased when Thr68 was phosphorylated. The peptide phosphorylated at Thr68, as well as four phospho-mimetic peptides (all containing the Thr68Glu mutation), showed the presence of a sequential NN(i,i + 1) nuclear Overhauser effect (NOE) in the 2D-¹H-NMR (two-dimensional–proton NMR) spectra, indicating the presence of turn-like conformations. Thus, the phosphorylation of Thr68 modulates the binding of NUPR1 to Impα3 by a conformational, entropy-driven switch from a random-coil conformation to a turn-like structure.

Nuclear protein 1 imparts oncogenic potential and chemotherapeutic resistance in cancer

Nuclear protein 1 (NUPR1) also known as p8 and candidate of metastasis 1 (COM1) functions as a transcriptional regulator, and plays a role in cell cycle, DNA damage response, apoptosis, autophagy, and chromatin remodeling in response to various cellular stressors. Since it was first suggested to contribute to cancer development and progression in 1999, a number of studies have sought to reveal its function. However, NUPR1 and its biological relevance in cancer have proven difficult to pinpoint. Based on evidence of NUPR1 expression in cancers, its function extends from carcinogenesis and tumorigenesis to metastasis and chemotherapeutic resistance. A tumor suppressive function of NUPR1 has also been documented in multiple cancers. By and large, literature involving NUPR1 and cancer is confined to pancreatic and breast cancers, yet significant progress has been made with respect to NUPR1 expression and its function in lung, colorectal, blood, and prostate cancers, among others. Recent evidence strongly supports the notion that NUPR1 is key in chemotherapeutic resistance by mediating both anti-apoptotic activity and autophagy when challenged with anti-cancer compounds. Therefore, it is of significant importance to understand the broad range of molecular functions directed by NUPR1. In this review, NUPR1 expression and its role in breast, lung, and colorectal cancer development and progression will be addressed.

Targeting intrinsically disordered proteins involved in cancer

Intrinsically disordered proteins (IDPs) do not have a well-defined structure under physiological conditions, but they have key roles in cell signaling and regulation, and they are frequently related to the development of diseases, such as cancer and other malignancies. This has converted IDPs in attractive therapeutic targets; however, targeting IDPs is challenging because of their dynamic nature. In the last years, different experimental and computational approaches, as well as the combination of both, have been explored to identify molecules to target either the hot-spots or the allosteric sites of IDPs. In this review, we summarize recent developments in successful targeting of IDPs, all of which are involved in different cancer types. The strategies used to develop and design (or in one particular example, to repurpose) small molecules targeting IDPs are, in a global sense, similar to those used in well-folded proteins: (1) screening of chemically diverse or target-oriented compound libraries; or (2) study of the interfaces involved in recognition of their natural partners, and design of molecular candidates capable of binding to such binding interface. We describe the outcomes of using these approaches in targeting IDPs involved in cancer, in the view to providing insight, to target IDPs in general. In a broad sense, the designed small molecules seem to target the most hydrophobic regions of the IDPs, hampering macromolecule (DNA or protein)-IDP interactions; furthermore, in most of the molecule-IDP complexes described so far, the protein remains disordered.

Targeting the Stress-Induced Protein NUPR1 to Treat Pancreatic Adenocarcinoma

Cancer cells activate stress-response mechanisms to adapt themselves to a variety of stressful conditions. Among these protective mechanisms, those controlled by the stress-induced nuclear protein 1 (NUPR1 ) belong to the most conserved ones. NUPR1 is an 82-residue-long, monomeric, basic and intrinsically disordered protein (IDP), which was found to be invariably overexpressed in some, if not all, cancer tissues. Remarkably, we and others have previously showed that genetic inactivation of the Nupr1 gene antagonizes the growth of pancreatic cancer as well as several other tumors. With the use of a multidisciplinary strategy by combining biophysical, biochemical, bioinformatic, and biological approaches, a trifluoperazine-derived compound, named ZZW-115, has been identified as an inhibitor of the NUPR1 functions. The anticancer activity of the ZZW-115 was first validated on a large panel of cancer cells. Furthermore, ZZW-115 produced a dose-dependent tumor regression of the tumor size in xenografted mice. Mechanistically, we have demonstrated that NUPR1 binds to several importins. Because ZZW-115 binds NUPR1 through the region around the amino acid Thr68, which is located into the nuclear location signal (NLS) region of the protein, we demonstrated that treatment with ZZW-115 inhibits completely the translocation of NUPR1 from the cytoplasm to the nucleus by competing with importins.

Dynamics of the intrinsically disordered protein NUPR1 in isolation and in its fuzzy complexes with DNA and prothymosin α

Intrinsically disordered proteins (IDPs) explore diverse conformations in their free states and, a few of them, also in their molecular complexes. This functional plasticity is essential for the function of IDPs, although their dynamics in both free and bound states is poorly understood. NUPR1 is a protumoral multifunctional IDP, activated during the acute phases of pancreatitis. It interacts with DNA and other IDPs, such as prothymosin α (ProTα), with dissociation constants of ~0.5 μM, and a 1:1 stoichiometry. We studied the structure and picosecond-to-nanosecond (ps-ns) dynamics by using both NMR and SAXS in: (i) isolated NUPR1; (ii) the NUPR1/ProTα complex; and (iii) the NUPR1/double stranded (ds) GGGCGCGCCC complex. Our SAXS findings show that NUPR1 remained disordered when bound to either partner, adopting a worm-like conformation; the fuzziness of bound NUPR1 was also pinpointed by NMR. Residues with the largest values of the relaxation rates (R₁, R_1ρ, R₂ and η_xy), in the free and bound species, were mainly clustered around the 30s region of the sequence, which agree with one of the protein hot-spots already identified by site-directed mutagenesis. Not only residues in this region had larger relaxation rates, but they also moved slower than the rest of the molecule, as indicated by the reduced spectral density approach (RSDA). Upon binding, the energy landscape of NUPR1 was not funneled down to a specific, well-folded conformation, but rather its backbone flexibility was kept, with distinct motions occurring at the hot-spot region.

Induction of nuclear protein-1 by thyroid hormone enhances platelet-derived growth factor A mediated angiogenesis in liver cancer

Background & Aims: Hepatocellular carcinoma (HCC) is among the leading causes of cancer deaths worldwide. Many studies indicate that disruption of cellular thyroid hormone signaling promotes HCC progression. However, the mechanisms underlying the regulation of genes downstream of thyroid hormone actions in HCC have remained elusive. In the current study, we identified NUPR1 (nuclear protein-1), a stress-induced protein that overexpresses in various neoplasia, is upregulated by triiodothyronine/thyroid hormone receptor (T₃/TR) signaling and aimed to elucidate its role in angiogenesis in cancer progression.

Methods: Quantitative reverse transcription-PCR, luciferase promoter and chromatin immunoprecipitation assays were performed to identify the NUPR1 regulatory mechanism by T₃/TR. In vitro and In vivo vascular formations were performed to detect the angiogenic function of NUPR1. Human angiogenesis arrays were performed to identify the downstream angiogenic pathway. The sorafenib resistant ability of TR/NUPR1 was further examined in vitro and in vivo. Clinical relevance of TR, NUPR1 and platelet-derived growth factor A (PDGFA) were investigate in HCC samples using qRT-PCR and western blot.

Results: Our experiments disclosed positive regulation of NUPR1 expression by T₃/TR through direct binding to the -2066 to -1910 region of the NUPR1 promoter. Elevated NUPR1 and TR expression link to poor survival in clinical HCC specimens. An analysis of clinicopathological parameters showed that expression of NUPR1 is associated with vascular invasion and pathology stage. Functional studies revealed that NUPR1 induced endothelial cell angiogenesis in vitro and in vivo. Using a human angiogenesis array, we identified PDGFA as a target of NUPR1 in the downstream angiogenic pathway. NUPR1 induced transcription of PDGFA through direct binding to the corresponding promoter region, and inhibition of the PDGFA signaling pathway impaired angiogenesis in human umbilical vein endothelial cells (HUVECs). Notably, the angiogenic effects of NUPR1/PDGFA were mediated by the MEK/ERK signaling pathway. TR/NUPR1 expression increased cell viability and resistance to sorafenib treatment. Moreover NUPR1 expression was positively correlated with TRα, TRβ, and PDGFA expression.

Conclusions: We propose that the T₃/TR/NUPR1/PDGFA/MEK/ERK axis has a vital role in hepatocarcinogenesis and suggest NUPR1 as a potential therapeutic target in HCC.

Ligand-based design identifies a potent NUPR1 inhibitor exerting anticancer activity via necroptosis

Intrinsically disordered proteins (IDPs) are emerging as attractive drug targets by virtue of their prevalence in various diseases including cancer. Drug development targeting IDPs is challenging because they have dynamical structure features and conventional drug design is not applicable. NUPR1 is an IDP playing an important role in pancreatic cancer. We previously reported that Trifluoperazine (TFP), an antipsychotic agent, was capable of binding to NUPR1 and inhibiting tumors growth. Unfortunately, TFP showed strong central nervous system side-effects. In this work, we undertook a multidisciplinary approach to optimize TFP, based on the synergy of computer modeling, chemical synthesis, and a variety of biophysical, biochemical and biological evaluations. A family of TFP-derived compounds was produced and the most active one, named ZZW-115, showed a dose-dependent tumor regression with no neurological effects and induced cell death mainly by necroptosis. This study opens a new perspective for drug development against IDPs, demonstrating the possibility of successful ligand-based drug design for such challenging targets.

Inactivation of NUPR1 promotes cell death by coupling ER-stress responses with necrosis

It was already described that genetic inhibition of NUPR1 induces tumor growth arrest. In this paper we studied the metabolism changes after NUPR1 downregulation in pancreatic cancer cells, which results in a significant decrease of OXPHOS activity with a concomitant lower ATP production which precedes the necrotic cell death. We demonstrated that NUPR1 downregulation induces a mitochondrial failure with a loss of the mitochondrial membrane potential, a strong increase in ROS production and a concomitant relocalization of mitochondria to the vicinity of the endoplasmic reticulum (ER). In addition, the transcriptomic analysis of NUPR1-deficient cells shows a decrease in the expression of some ER stress response-associated genes. Indeed, in ER stressors-treated cells with thapsigargin, brefeldin A or tunicamycin, a greater increase in necrosis and decrease of ATP content was observed in NUPR1-defficent cells. Finally, in vivo experiments, using acute pancreatitis which induces ER stress as well as NUPR1 activation, we observed that NUPR1 expression protects acinar cells from necrosis in mice. Importantly, we also report that the cell death observed after knocking-down NUPR1 expression is completely reversed by incubation with Necrostatin-1, but not by inhibiting caspase activity with Z-VAD-FMK. Altogether, these data enable us to describe a model in which inactivation of NUPR1 in pancreatic cancer cells results in an ER stress that induces a mitochondrial malfunction, a deficient ATP production and, as consequence, the cell death mediated by a programmed necrosis.

The chromatin nuclear protein NUPR1L is intrinsically disordered and binds to the same proteins as its paralogue

NUPR1 is a protumoral multifunctional intrinsically disordered protein (IDP), which is activated during the acute phases of pancreatitis. It interacts with other IDPs such as prothymosin α, as well as with folded proteins such as the C-terminal region of RING1-B (C-RING1B) of the Polycomb complex; in all those interactions, residues around Ala33 and Thr68 (the ‘hot-spot’ region) of NUPR1 intervene. Its paralogue, NUPR1L, is also expressed in response to DNA damage, it is p53-regulated, and its expression down-regulates that of the NUPR1 gene. In this work, we characterized the conformational preferences of isolated NUPR1L and its possible interactions with the same molecular partners of NUPR1. Our results show that NUPR1L was an oligomeric IDP from pH 2.0 to 12.0, as judged by steady-state fluorescence, circular dichroism (CD), dynamic light scattering, 1D 1H-NMR (nuclear magnetic resonance), and as indicated by structural modelling. However, in contrast with NUPR1, there was evidence of local helical- or turn-like structures; these structures were not rigid, as judged by the lack of sigmoidal behaviour in the chemical and thermal denaturation curves obtained by CD and fluorescence. Interestingly enough, NUPR1L interacted with prothymosin α and C-RING1B, and with a similar affinity to that of NUPR1 (in the low micromolar range). Moreover, NUPR1L hetero-associated with NUPR1 with an affinity of 0.4 µM and interacted with the ‘hot-spot’ region of NUPR1. Thus, we suggest that the regulation of NUPR1 gene by NUPR1L does not only happen at the DNA level, but it could also involve direct interactions with NUPR1 natural partners.

p8 deficiency leads to elevated pancreatic beta cell mass but does not contribute to insulin resistance in mice fed with high-fat diet

BACKGROUND

p8 was initially described as being overexpressed in acute pancreatitis and encoding a ubiquitous stress protein. Analysis of insulin sensitivity and glucose tolerance in p8-knockout and haplodeficient mice revealed counterintuitive results. Thus, we determined glycemic control of p8 in mice fed with standard (SD) and high-fat diet (HFD).

METHODS

p8-/- and wild type (p8+/+) mice were used for analysis of glucagon (immunohistochemistry), insulin levels (ELISA) and beta cell mass. Hyperinsulinemic- euglycemic glucose clamp technique, i.p. glucose tolerance test (ipGTT), i.p. insulin tolerance test (ipITT) and metabolic chamber analysis were performed in SD (4% fat) and HFD (55% fat) groups.

RESULTS

p8-/- mice showed no differences in glucagon or insulin content but higher insulin secretion from pancreatic islets upon glucose stimulation. p8 deficiency resulted in elevated beta cell mass but was not associated with increased insulin resistance in ipGTT or ipITT. Glucose clamp tests also revealed no evidence of association of p8 deficiency with insulin resistance. Metabolic chamber analysis showed equal energy expenditure in p8-/- mice and wild type animals.

CONCLUSION

p8 depletion may contribute to glucose metabolism via stress-induced insulin production and elevated beta cell mass. Nevertheless, p8 knockout showed no impact on insulin resistance in SD and HFD-fed mice.

The current state and future perspectives of cannabinoids in cancer biology

To date, cannabinoids have been allowed in the palliative medicine due to their analgesic and antiemetic effects, but increasing number of preclinical studies indicates their anticancer properties. Cannabinoids exhibit their action by a modulation of the signaling pathways crucial in the control of cell proliferation and survival. Many in vitro and in vivo experiments have shown that cannabinoids inhibit proliferation of cancer cells, stimulate autophagy and apoptosis, and have also a potential to inhibit angiogenesis and metastasis. In this review, we present an actual state of knowledge regarding molecular mechanisms of cannabinoids' anticancer action, but we discuss also aspects that are still not fully understood such as the role of the endocannabinoid system in a carcinogenesis, the impact of cannabinoids on the immune system in the context of cancer development, or the cases of a stimulation of cancer cells' proliferation by cannabinoids. The review includes also a summary of currently ongoing clinical trials evaluating the safety and efficacy of cannabinoids as anticancer agents.

Intrinsically disordered chromatin protein NUPR1 binds to the C-terminal region of Polycomb RING1B

Intrinsically disordered proteins (IDPs) are ubiquitous in eukaryotes, and they are often associated with diseases in humans. The protein NUPR1 is a multifunctional IDP involved in chromatin remodeling and in the development and progression of pancreatic cancer; however, the details of such functions are unknown. Polycomb proteins are involved in specific transcriptional cascades and gene silencing. One of the proteins of the Polycomb complex is the Ring finger protein 1 (RING1). RING1 is related to aggressive tumor features in multiple cancer types. In this work we characterized the interaction between NUPR1 and the paralogue RING1B in vitro, in silico, and in cellulo. The interaction occurred through the C-terminal region of RING1B (C-RING1B), with an affinity in the low micromolar range (∼10 μM). The binding region of NUPR1, mapped by NMR, was a hydrophobic polypeptide patch at the 30s region of its sequence, as pinpointed by computational results and site-directed mutagenesis at Ala33. The association between C-RING1B and wild-type NUPR1 also occurred in cellulo as tested by protein ligation assays; this interaction is inhibited by trifluoperazine, a drug known to hamper binding of wild-type NUPR1 with other proteins. Furthermore, the Thr68Gln and Ala33Gln/Thr68Gln mutants had a reduction in the binding toward C-RING1B as shown by in vitro, in silico, and in cellulo studies. This is an example of a well-folded partner of NUPR1, because its other interacting proteins are also unfolded. We hypothesize that NUPR1 plays an active role in chromatin remodeling and carcinogenesis, together with Polycomb proteins.

Nupr1 Modulates Methamphetamine-Induced Dopaminergic Neuronal Apoptosis and Autophagy through CHOP-Trib3-Mediated Endoplasmic Reticulum Stress Signaling Pathway

Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH exposure causes detrimental effects on multiple organ systems, primarily the nervous system, especially dopaminergic pathways, in both laboratory animals and humans. In this study, we hypothesized that Nuclear protein 1 (Nupr1/com1/p8) is involved in METH-induced neuronal apoptosis and autophagy through endoplasmic reticulum (ER) stress signaling pathway. To test this hypothesis, we measured the expression levels of Nupr1, ER stress protein markers CHOP and Trib3, apoptosis-related protein markers cleaved-caspase3 and PARP, as well as autophagy-related protein markers LC3 and Beclin-1 in brain tissues of adult male Sprague-Dawley (SD) rats, rat primary cultured neurons and the rat adrenal pheochromocytoma cells (PC12 cells) after METH exposure. We also determined the effects of METH exposure on the expression of these proteins after silencing Nupr1, CHOP, or Trib3 expression with synthetic small hairpin RNA (shRNA) or siRNA in vitro, and after silencing Nupr1 in the striatum of rats by injecting lentivirus containing shRNA sequence targeting Nupr1 gene to rat striatum. The results showed that METH exposure increased Nupr1 expression that was accompanied with increased expression of ER stress protein markers CHOP and Trib3, and also led to apoptosis and autophagy in rat primary neurons and in PC12 cells after 24 h exposure (3.0 mM), and in the prefrontal cortex and striatum of rats after repeated intraperitoneal injections (15 mg/kg × 8 injections at 12 h intervals). Silencing of Nupr1 expression partly reduced METH-induced apoptosis and autophagy in vitro and in vivo. These results suggest that Nupr1 plays an essential role in METH-caused neuronal apoptosis and autophagy at relatively higher doses and may be a potential therapeutic target in high-dose METH-induced neurotoxicity.

Identification of a Drug Targeting an Intrinsically Disordered Protein Involved in Pancreatic Adenocarcinoma

Intrinsically disordered proteins (IDPs) are prevalent in eukaryotes, performing signaling and regulatory functions. Often associated with human diseases, they constitute drug-development targets. NUPR1 is a multifunctional IDP, over-expressed and involved in pancreatic ductal adenocarcinoma (PDAC) development. By screening 1120 FDA-approved compounds, fifteen candidates were selected, and their interactions with NUPR1 were characterized by experimental and simulation techniques. The protein remained disordered upon binding to all fifteen candidates. These compounds were tested in PDAC-derived cell-based assays, and all induced cell-growth arrest and senescence, reduced cell migration, and decreased chemoresistance, mimicking NUPR1-deficiency. The most effective compound completely arrested tumor development in vivo on xenografted PDAC-derived cells in mice. Besides reporting the discovery of a compound targeting an intact IDP and specifically active against PDAC, our study proves the possibility to target the ‘fuzzy’ interface of a protein that remains disordered upon binding to its natural biological partners or to selected drugs.

Knockdown of NUPR1 inhibits the proliferation of glioblastoma cells via ERK1/2, p38 MAPK and caspase-3

Nuclear protein-1 (NUPR1), located on chromosome 16p11.2, is a stress response factor that plays an important role in the growth and migration of human malignant tumor cells. However, the role of NUPR1 in glioblastoma remains poorly understood. The expression level of NUPR1 was detected by quantitative real-time PCR and immunohistochemistry (IHC). Wound healing, MTT, cell counting and BrdU assays were used to analyze the migration and proliferation of glioblastoma cells after down-regulating NUPR1 expression using a lentiviral vector. FACS analysis and a signaling antibody array kit were used to detect the mechanism by which NUPR1 modulates cell cycle and apoptosis activities in glioblastoma cells. We confirmed that NUPR1 was up-regulated in glioblastoma tissues compared to NB tissues. Down-regulation of NUPR1 suppressed cell migration and proliferation, arrested the cell cycle in the G0/G1 phase and promoted apoptosis in U251 and U87 cells in vitro. Furthermore, the expression levels of phosphorylated ERK1/2, p38 MAPK and cleaved caspase-3 were decreased upon silencing NUPR1 expression in U251 and U87 cells. In summary, NUPR1 plays an important role in the growth and migration of human glioblastoma cells. Knockdown of NUPR1 suppressed glioblastoma cell growth by arresting the cell cycle and inducing cell apoptosis via decreases in the expression of ERK1/2, p38 MAPK and caspase-3.

Determinants of the pKa values of ionizable residues in an intrinsically disordered protein

Intrinsically disordered proteins (IDPs) are prevalent in eukaryotes; in humans, they are often associated with diseases. The protein NUPR1 is a multifunctional IDP involved in the development and progression of pancreatic cancer; therefore, it constitutes a target for drug design. In an effort to contribute to the understanding of the conformational features of NUPR1 and to provide clues on amino acid interactions in disordered states of proteins, we measured the pKa values of all its acidic groups (aspartic and glutamic residues, and backbone C terminus) by using NMR spectroscopy at low (100 mM) and high (500 mM) NaCl concentration. At low ionic strength, the pKa values were similar to those reported for random-coil models, except for Glu18 and Asp19, suggesting electrostatic interactions around these residues. Molecular modelling and simulation indicate an additional, significant role of nearby proline residues in determining the polypeptide conformational features and water accessibility in the region around Glu18, modulating the titration properties of these amino acids. In the other acidic residues of NUPR1, the small deviations of pKa values (compared to those expected for a random-coil) are likely due to electrostatic interactions with charged adjacent residues, which should be reduced at high NaCl concentrations. In fact, at high ionic strength, the pKa values of the aspartic residues were similar to those in a random coil, but there were still small differences for those of glutamic acids, probably due to hydrogen-bond formation. The overall findings suggest that local interactions and hydrophobic effects play a major role in determining the electrostatic features of NUPR1, whereas long-range charge contributions appear to be of lesser importance.

Anticancer mechanisms of cannabinoids

In addition to the well-known palliative effects of cannabinoids on some cancer-associated symptoms, a large body of evidence shows that these molecules can decrease tumour growth in animal models of cancer. They do so by modulating key cell signalling pathways involved in the control of cancer cell proliferation and survival. In addition, cannabinoids inhibit angiogenesis and decrease metastasis in various tumour types in laboratory animals. In this review, we discuss the current understanding of cannabinoids as antitumour agents, focusing on recent discoveries about their molecular mechanisms of action, including resistance mechanisms and opportunities for their use in combination therapy. Those observations have already contributed to the foundation for the development of the first clinical studies that will analyze the safety and potential clinical benefit of cannabinoids as anticancer agents.

Macrophage cell death and transcriptional response are actively triggered by the fungal virulence factor Cbp1 during H. capsulatum infection

Microbial pathogens induce or inhibit death of host cells during infection, with significant consequences for virulence and disease progression. Death of an infected host cell can either facilitate release and dissemination of intracellular pathogens or promote pathogen clearance. Histoplasma capsulatum is an intracellular fungal pathogen that replicates robustly within macrophages and triggers macrophage lysis by unknown means. To identify H. capsulatum effectors of macrophage lysis, we performed a genetic screen and discovered three mutants that grew to wild-type levels within macrophages but failed to elicit host-cell death. Each mutant was defective in production of the previously identified secreted protein Cbp1 (calcium-binding protein 1), whose role in intracellular growth had not been fully investigated. We found that Cbp1 was dispensable for high levels of intracellular growth but required to elicit a unique transcriptional signature in macrophages, including genes whose induction was previously associated with endoplasmic reticulum stress and host-cell death. Additionally, Cbp1 was required for activation of cell-death caspases-3/7, and macrophage death during H. capsulatum infection was dependent on the pro-apoptotic proteins Bax and Bak. Taken together, these findings strongly suggest that the ability of Cbp1 to actively program host-cell death is an essential step in H. capsulatum pathogenesis.

Functional Characterization of Nupr1L, A Novel p53-Regulated Isoform of the High-Mobility Group (HMG)-Related Protumoral Protein Nupr1

We have previously demonstrated a crucial role of nuclear protein 1 (NUPR1) in tumor development and progression. In this work, we report the functional characterization of a novel Nupr1-like isoform (NUPR1L) and its functional interaction with the protumoral factor NUPR1. Through the use of primary sequence analysis, threading, and homology-based molecular modeling, as well as expression and immunolocalization, studies reveal that NUPR1L displays properties, which are similar to member of the HMG-like family of chromatin regulators, including its ability to translocate to the cell nucleus and bind to DNA. Analysis of the NUPR1L promoter showed the presence of two p53-response elements at positions -37 and -7, respectively. Experiments using reporter assays combined with site-directed mutagenesis and using cells with controllable p53 expression demonstrate that both of these sequences are responsible for the regulation of NUPR1L expression by p53. Congruently, NUPR1L gene expression is activated in response to DNA damage induced by oxaliplatin treatment or cell cycle arrest induced by serum starvation, two well-validated methods to achieve p53 activation. Interestingly, expression of NUPR1L downregulates the expression of NUPR1, its closely related protumoral isoform, by a mechanism that involves the inhibition of its promoter activity. At the cellular level, overexpression of NUPR1L induces G1 cell cycle arrest and a decrease in their cell viability, an effect that is mediated, at least in part, by downregulating NUPR1 expression. Combined, these experiments constitute the first functional characterization of NUPR1L as a new p53-induced gene, which negatively regulates the protumoral factor NUPR1.

Identification of a mitochondrial defect gene signature reveals NUPR1 as a key regulator of liver cancer progression

Many cancer cells require more glycolytic adenosine triphosphate production due to a mitochondrial respiratory defect. However, the roles of mitochondrial defects in cancer development and progression remain unclear. To address the role of transcriptomic regulation by mitochondrial defects in liver cancer cells, we performed gene expression profiling for three different cell models of mitochondrial defects: cells with chemical respiratory inhibition (rotenone, thenoyltrifluoroacetone, antimycin A, and oligomycin), cells with mitochondrial DNA depletion (Rho0), and liver cancer cells harboring mitochondrial defects (SNU354 and SNU423). By comparing gene expression in the three models, we identified 10 common mitochondrial defect-related genes that may be responsible for retrograde signaling from cancer cell mitochondria to the intracellular transcriptome. The concomitant expression of the 10 common mitochondrial defect genes is significantly associated with poor prognostic outcomes in liver cancers, suggesting their functional and clinical relevance. Among the common mitochondrial defect genes, we found that nuclear protein 1 (NUPR1) is one of the key transcription regulators. Knockdown of NUPR1 suppressed liver cancer cell invasion, which was mediated in a Ca(2+) signaling-dependent manner. In addition, by performing an NUPR1-centric network analysis and promoter binding assay, granulin was identified as a key downstream effector of NUPR1. We also report association of the NUPR1-granulin pathway with mitochondrial defect-derived glycolytic activation in human liver cancer.

CONCLUSION

Mitochondrial respiratory defects and subsequent retrograde signaling, particularly the NUPR1-granulin pathway, play pivotal roles in liver cancer progression.

From cell senescence to age-related diseases: differential mechanisms of action of senescence-associated secretory phenotypes

Cellular senescence is a process by which cells enter a state of permanent cell cycle arrest. It is commonly believed to underlie organismal aging and age-associated diseases. However, the mechanism by which cellular senescence contributes to aging and age-associated pathologies remains unclear. Recent studies showed that senescent cells exert detrimental effects on the tissue microenvironment, generating pathological facilitators or aggravators. The most significant environmental effector resulting from senescent cells is the senescence-associated secretory phenotype (SASP), which is constituted by a strikingly increased expression and secretion of diverse pro-inflammatory cytokines. Careful investigation into the components of SASPs and their mechanism of action, may improve our understanding of the pathological backgrounds of age-associated diseases. In this review, we focus on the differential expression of SASP-related genes, in addition to SASP components, during the progress of senescence. We also provide a perspective on the possible action mechanisms of SASP components, and potential contributions of SASP-expressing senescent cells, to age-associated pathologies.

Endocannabinoids and Cancer

A large body of evidence shows that cannabinoids, in addition to their well-known palliative effects on some cancer-associated symptoms, can reduce tumour growth in animal models of cancer. They do so by modulating key cell signalling pathways involved in the control of cancer cell proliferation and survival. In addition, cannabinoids inhibit angiogenesis and cell proliferation in different types of tumours in laboratory animals. By contrast, little is known about the biological role of the endocannabinoid system in cancer physio-pathology, and several studies suggest that it may be over-activated in cancer. In this review, we discuss our current understanding of cannabinoids as antitumour agents, focusing on recent advances in the molecular mechanisms of action, including resistance mechanisms and opportunities for combination therapy approaches.

P8 deficiency increases cellular ROS and induces HO-1

The gene p8 encodes for a small cytoprotective protein with no apparent enzymatic activity being proposed to act as co-transcription factor whose expression is increased during inflammation. Recent data from astrocytes demonstrates that p8 suppression leads to induction of heme oxygenase 1 (HO-1). Here, we assessed the cross-talk between p8 and HO-1 in mouse embryonic fibroblasts (MEF) observing an increased expression of HO-1 in p8-deficient (p8(-/-)) MEFs in non-treated and treated conditions. This effect was independent of the cell cycle. Our findings revealed that generation of reactive oxygen species (ROS) was higher in p8(-/-) MEFs. Mitochondria and NADPH oxidases were not the origin of ROS. This observation was not restricted to MEF as suppression of p8 gene transcription in MiaPaCa-2 cells also led to increased intracellular ROS. Additionally, p8 deficiency did not affect the Rac1 dependant NADPH oxidase complex. Our data shows that p8 deficiency increases ROS and subsequently the expression of anti-oxidative enzymes, such as HO-1, suggesting an involvement in the anti-oxidative defense. Moreover, we suggest that the severity of AP observed in p8(-/-) mice is induced by an impaired anti oxidative capacity of the pancreas, which is caused by increased generation of ROS.

RAD9 deficiency enhances radiation induced bystander DNA damage and transcriptomal response

BACKGROUND

Radiation induced bystander effects are an important component of the overall response of cells to irradiation and are associated with human health risks. The mechanism responsible includes intra-cellular and inter-cellular signaling by which the bystander response is propagated. However, details of the signaling mechanism are not well defined.

METHODS

We measured the bystander response of Mrad9+/+ and Mrad9-/- mouse embryonic stem cells, as well as human H1299 cells with inherent or RNA interference-mediated reduced RAD9 levels after exposure to 1 Gy α particles, by scoring chromosomal aberrations and micronuclei formation, respectively. In addition, we used microarray gene expression analyses to profile the transcriptome of directly irradiated and bystander H1299 cells.

RESULTS

We demonstrated that Mrad9 null enhances chromatid aberration frequency induced by radiation in bystander mouse embryonic stem cells. In addition, we found that H1299 cells with reduced RAD9 protein levels showed a higher frequency of radiation induced bystander micronuclei formation, compared with parental cells containing inherent levels of RAD9. The enhanced bystander response in human cells was associated with a unique transcriptomic profile. In unirradiated cells, RAD9 reduction broadly affected stress response pathways at the mRNA level; there was reduction in transcript levels corresponding to genes encoding multiple members of the UVA-MAPK and p38MAPK families, such as STAT1 and PARP1, suggesting that these signaling mechanisms may not function optimally when RAD9 is reduced. Using network analysis, we found that differential activation of the SP1 and NUPR1 transcriptional regulators was predicted in directly irradiated and bystander H1299 cells. Transcription factor prediction analysis also implied that HIF1α (Hypoxia induced factor 1 alpha) activation by protein stabilization in irradiated cells could be a negative predictor of the bystander response, suggesting that local hypoxic stress experienced by cells directly exposed to radiation may influence whether or not they will elicit a bystander response in neighboring cells.

Evidence supporting the existence of a NUPR1-like family of helix-loop-helix chromatin proteins related to, yet distinct from, AT hook-containing HMG proteins

NUPR1, a small chromatin protein, plays a critical role in cancer development, progression, and resistance to therapy. Here, using a combination of structural bioinformatics and molecular modeling methods, we report several novel findings that enhance our understanding of the biochemical function of this protein. We find that NUPR1 has been conserved throughout evolution, and over time it has undergone duplications and transpositions to form other transcriptional regulators. Using threading, homology-based molecular modeling, molecular mechanics calculations, and molecular dynamics simulations, we generated structural models for four of these proteins: NUPR1a, NUPR1b, NUPR2, and the NUPR-like domain of GTF2-I. Comparative analyses of these models combined with extensive linear motif identification reveal that these four proteins, though similar in their propensities for folding, differ in size, surface changes, and sites amenable for posttranslational modification. Lastly, taking NUPR1a as the paradigm for this family, we built models of a NUPR–DNA complex. Additional structural comparisons revealed that NUPR1 defines a new family of small-groove-binding proteins that share structural features with, yet are distinct from, helix-loop-helix AT-hook-containing HMG proteins. These models and inferences should lead to a better understanding of the function of this group of chromatin proteins, which play a critical role in the development of human malignant diseases.

Expression and roles of As-NUPR1 protein from Artemia sinica during embryo development and in response to salinity stress

As-NUPR1, a stress-related protein, plays an important role in post-diapause during embryonic development in the brine shrimp Artemia sinica. In the present study, successful expression of As-NUPR1 from the cDNA sequence isolated from A. sinica was demonstrated using a prokaryotic expression system. The recombinant protein consisted of 132 amino acids with a molecular weight of 15 kDa, and a predicted isoelectric point of 7.17. As-NUPR1 polyclonal antibodies were prepared by immunization of Balb/c mice with purified recombinant As-NUPR1 protein as an antigen, and immunological studies were carried out. Expression of As-NUPR1 during different developmental stages of the embryo and in response to salinity stress was analyzed in A. sinica using Western blots. The experimental results showed that the expression of As-NUPR1 is widely distributed at different developmental stages in A. sinica, and there was no tissue or organ specificity. Expression of As-NUPR1 decreased gradually during the diapause termination stage of embryo development, after which there was a general increase in expression after breaking the shell. In addition, As-NUPR1 expression was highly upregulated under conditions of high salinity. These results suggest that the As-NUPR1 protein is a stress-related protein that plays a role in protecting embryos from high salt damage in different embryonic developmental stages, especially during the post-diapause period.

Nupr1 deletion protects against glucose intolerance by increasing beta cell mass

AIMS/HYPOTHESIS

The stress-activated nuclear protein transcription regulator 1 (NUPR1) is induced in response to glucose and TNF-α, both of which are elevated in type 2 diabetes, and Nupr1 has been implicated in cell proliferation and apoptosis cascades. We used Nupr1(-/-) mice to study the role of Nupr1 in glucose homeostasis under normal conditions and following maintenance on a high-fat diet (HFD).

METHODS

Glucose homeostasis in vivo was determined by measuring glucose tolerance, insulin sensitivity and insulin secretion. Islet number, morphology and beta cell area were assessed by immunofluorescence and morphometric analysis, and islet cell proliferation was quantified by analysis of BrdU incorporation. Islet gene expression was measured by gene arrays and quantitative RT-PCR, and gene promoter activities were monitored by measuring luciferase activity.

RESULTS

Nupr1(-/-) mice had increased beta cell mass as a consequence of enhanced islet cell proliferation. Nupr1-dependent suppression of beta cell Ccna2 and Tcf19 promoter activities was identified as a mechanism through which Nupr1 may regulate beta cell cycle progression. Nupr1(-/-) mice maintained on a normal diet were mildly insulin resistant, but were normoglycaemic with normal glucose tolerance because of compensatory increases in basal and glucose-induced insulin secretion. Nupr1 deletion was protective against HFD-induced obesity, insulin resistance and glucose intolerance.

CONCLUSIONS/INTERPRETATION

Inhibition of NUPR1 expression or activity has the potential to protect against the metabolic defects associated with obesity and type 2 diabetes.

Deciphering the binding between Nupr1 and MSL1 and their DNA-repairing activity

The stress protein Nupr1 is a highly basic, multifunctional, intrinsically disordered protein (IDP). MSL1 is a histone acetyl transferase-associated protein, known to intervene in the dosage compensation complex (DCC). In this work, we show that both Nupr1 and MSL1 proteins were recruited and formed a complex into the nucleus in response to DNA-damage, which was essential for cell survival in reply to cisplatin damage. We studied the interaction of Nupr1 and MSL1, and their binding affinities to DNA by spectroscopic and biophysical methods. The MSL1 bound to Nupr1, with a moderate affinity (2.8 µM) in an entropically-driven process. MSL1 did not bind to non-damaged DNA, but it bound to chemically-damaged-DNA with a moderate affinity (1.2 µM) also in an entropically-driven process. The Nupr1 protein bound to chemically-damaged-DNA with a slightly larger affinity (0.4 µM), but in an enthalpically-driven process. Nupr1 showed different interacting regions in the formed complexes with Nupr1 or DNA; however, they were always disordered (“fuzzy”), as shown by NMR. These results underline a stochastic description of the functionality of the Nupr1 and its other interacting partners.

Biotic acts of antibiotics

Biological functions of antibiotics are not limited to killing. The most likely function of antibiotics in natural microbial ecosystems is signaling. Does this signaling function of antibiotics also extend to the eukaryotic – in particular mammalian – cells? In this review, the host modulating properties of three classes of antibiotics (macrolides, tetracyclines, and β-lactams) will be briefly discussed. Antibiotics can be effective in treatment of a broad spectrum of diseases and pathological conditions other than those of infectious etiology and, in this capacity, may find widespread applications beyond the intended antimicrobial use. This use, however, should not compromise the primary function antibiotics are used for. The biological background for this inter-kingdom signaling is also discussed.

pH-dependent solution structure and activity of a reduced form of the host-defense peptide myticin C (Myt C) from the mussel Mytilus galloprovincialis

Myticin C (Myt C) is a highly variable host-defense peptide (HDP) associated to the immune response in the mediterranean mussel (Mytilus galloprovincialis), which has shown to be active across species due to its strong antiviral activity against a fish rhabdovirus found in fish cells overexpressing this HDP. However, the potential antimicrobial properties of any synthetic analogue of Myt C has not yet been analysed. Thus, in this work we have synthesised the sequence of the mature peptide of Myt C variant c and analysed the structure activity relationships of its reduced (non-oxidized) form (red-MytCc). In contrast to results previously reported for oxidized isoforms of mussel myticins, red-MytCc was not active against bacteria at physiological pH and showed a moderate antiviral activity against the viral haemorrhagic septicaemia (VHS) rhabdovirus. However, its chemotactic properties remained active. Structure/function studies in neutral and acid environments by means of infrared spectroscopy indicated that the structure of red-MytCc is pH dependent, with acid media increasing its alpha-helical content. Furthermore, red-MytCc was able to efficiently aggregate artificial phospholipid membranes at low pH, as well as to inhibit the Escherichia coli growth, suggesting that this activity is attributable to its more structured form in an acidic environment. All together, these results highlight the dynamic and environmentally sensitive behavior of red-Myt C in solution, and provide important insights into Myt C structure/activity relationships and the requirements to exert its antimicrobial/immunomodulatory activities. On the other hand, the pH-dependent direct antimicrobial activity of Myt C suggests that this HDP may be a suitable template for the development of antimicrobial agents that would function selectively in specific pH environments, which are sorely needed in this "antibiotic-resistance era".

Localization, developmental regulation and stress induction of p8-L1 and p8-L2 in zebrafish

The transcription cofactor, p8, has a basic helix-loop-helix motif and is involved in several metabolic processes. It has previously been reported that p8 plays an important role in stress response in zebrafish. We expanded on these studies to further investigate the roles of two p8-like cDNAs found in zerbrafish, p8-L1 and p8-L2. Zebrafish p8-L1 and p8-L2 cDNAs consist of 742 bp and 813 bp, respectively. Both have the same open reading frame despite different genomic structures and encode a 76 amino acid polypeptide with conserved a Phospho_p8 domain. These two cDNA’s were abundant in different tissues in the zebrafish: p8-L1 was high in intestine and muscle tissue and in low abundance in the backbone, whereas the highest amount of p8-L2 was found in the backbone, similar to p8. During embryogenesis, both p8-L1 and p8-L2 were abundant at the cleavage stage and decreased gradually in abundance from blastula to pharyngula stage. However, p8-L1 abundance increased during hatching as observed in p8. Quantitative real-time PCR assay suggested that p8-L1 and p8-L2 were both up-regulated significantly under osmotic pressure and pH value challenges, suggesting an important role of p8-L1 and p8-L2 genes in stress response.

Molecular characterization and expression of As-nurp1 gene from Artemia sinica during development and in response to salinity and temperature stress

Nuclear protein 1 (NURP1) is a stress-related protein and closely related to diapause in the development of Artemia. In the present paper, the full-length 568-bp cDNA sequence of the nurp1 homolog of Artemia sinica (As-nurp1) was isolated by RACE technology for the first time. The putative As-nurp1 protein consists of 66 amino acids with a basic helix-loop-helix (bHLH) motif and a bipartite nuclear localization signal (NLS). Multiple sequence alignments revealed that the putative As-nurp1 protein sequence was relatively conserved across species, especially in the bHLH domain. The expression of As-nurp1 is widely distributed during A. sinica development. This is followed by a dramatic downregulation after diapause and is newly upregulated from the larval nauplius stage. Furthermore, As-nurp1 transcripts are highly upregulated under conditions of high salinity and low temperature. These findings suggest that As-nurp1 is stress-related and may act as a protective factor in embryonic development.

Towards the use of cannabinoids as antitumour agents

Various reports have shown that cannabinoids (the active components of marijuana and their derivatives) can reduce tumour growth and progression in animal models of cancer, in addition to their well-known palliative effects on some cancer-associated symptoms. This Opinion article discusses our current understanding of cannabinoids as antitumour agents, focusing on recent insights into the molecular mechanisms of action, including emerging resistance mechanisms and opportunities for combination therapy approaches. Such knowledge is required for the optimization of preclinical cannabinoid-based therapies and for the preliminary clinical testing that is currently underway.