The functions and roles of sestrins in regulating human diseases

Sestrins (Sesns), highly conserved stress-inducible metabolic proteins, are known to protect organisms against various noxious stimuli including DNA damage, oxidative stress, starvation, endoplasmic reticulum (ER) stress, and hypoxia. Sesns regulate metabolism mainly through activation of the key energy sensor AMP-dependent protein kinase (AMPK) and inhibition of mammalian target of rapamycin complex 1 (mTORC1). Sesns also play pivotal roles in autophagy activation and apoptosis inhibition in normal cells, while conversely promoting apoptosis in cancer cells. The functions of Sesns in diseases such as metabolic disorders, neurodegenerative diseases, cardiovascular diseases, and cancer have been broadly investigated in the past decades. However, there is a limited number of reviews that have summarized the functions of Sesns in the pathophysiological processes of human diseases, especially musculoskeletal system diseases. One aim of this review is to discuss the biological functions of Sesns in the pathophysiological process and phenotype of diseases. More significantly, we include some new evidence about the musculoskeletal system. Another purpose is to explore whether Sesns could be potential biomarkers or targets in the future diagnostic and therapeutic process.

Posttreatment Strategy Against Hypoxia and Ischemia Based on Selective Targeting of Nonnuclear Estrogen Receptors with PaPE-1

Newly synthesized Pathway Preferential Estrogen-1 (PaPE-1) selectively activates membrane estrogen receptors (mERs), namely, mERα and mERβ, and has been shown to evoke neuroprotection; however, its effectiveness in protecting brain tissue against hypoxia and ischemia has not been verified in a posttreatment paradigm. This is the first study showing that a 6-h delayed posttreatment with PaPE-1 inhibited hypoxia/ischemia-induced neuronal death, as indicated by neutral red uptake in mouse primary cell cultures in vitro. The effect was accompanied by substantial decreases in neurotoxicity and neurodegeneration in terms of LDH release and Fluoro-Jade C staining of damaged cells, respectively. The mechanisms of the neuroprotective action of PaPE-1 also involved apoptosis inhibition demonstrated by normalization of both mitochondrial membrane potential and expression levels of apoptosis-related genes and proteins such as Fas, Fasl, Bcl2, FAS, FASL, BCL2, BAX, and GSK3β. Furthermore, PaPE-1-evoked neuroprotection was mediated through a reduction in ROS formation and restoration of cellular metabolic activity that had become dysregulated due to hypoxia and ischemia. These data provide evidence that targeting membrane non-GPER estrogen receptors with PaPE-1 is an effective therapy that protects brain neurons from hypoxic/ischemic damage, even when applied with a 6-h delay from injury onset.

Unravelling similarities and differences in the role of circular and linear PVT1 in cancer and human disease

The plasmacytoma variant translocation 1 (PVT1) is a long non-coding RNA gene involved in human disease, mainly in cancer onset/progression. Although widely analysed, its biological roles need to be further clarified. Notably, functional studies on PVT1 are complicated by the occurrence of multiple transcript variants, linear and circular, which generate technical issues in the experimental procedures used to evaluate its impact on human disease. Among the many PVT1 transcripts, the linear PVT1 (lncPVT1) and the circular hsa_circ_0001821 (circPVT1) are frequently reported to perform similar pathologic and pro-tumorigenic functions when overexpressed. The stimulation of cell proliferation, invasion and drug resistance, cell metabolism regulation, and apoptosis inhibition is controlled through multiple targets, including MYC, p21, STAT3, vimentin, cadherins, the PI3K/AKT, HK2, BCL2, and CASP3. However, some of this evidence may originate from an incorrect evaluation of these transcripts as two separate molecules, as they share the lncPVT1 exon-2 sequence. We here summarise lncPVT1/circPVT1 functions by mainly focusing on shared pathways, pointing out the potential bias that may exist when the biological role of each transcript is analysed. These considerations may improve the knowledge about lncPVT1/circPVT1 and their specific targets, which deserve further studies due to their diagnostic, prognostic, and therapeutic potential.

WEE1 promotes endometriosis via the Wnt/β-catenin signaling pathway

Background Endometriosis, the presence of active endometrial tissue outside the lining membrane of the uterine cavity, is a common disease in women of childbearing age. The ectopic endometrium has some characteristics of tumor tissue, including invasive and migratory abilities. In addition, endometriosis is associated with inflammation and reduced cellular apoptosis. Methods Western blot analysis, qPCR, immunohistochemistry, immunofluorescence microscopy, Transwell assay, wound healing assay, and TUNEL staining. Results Interleukin-1β (IL-1β) induced WEE1 expression in endometrial stromal cells (ESCs), suggesting that WEE1 may be upregulated during the endometriosis-induced inflammatory response. Overexpression of WEE1 in cultured ESCs promoted ESC migration while inhibiting apoptosis, whereas WEE1 knockdown reduced ESC migration while promoting apoptosis. Inhibition of WEE1 attenuates fibrosis in ESCs and female C57BL/6 J mice. This pro-fibrotic effect of WEE1 was significantly decreased by treatment with the Wnt/β-catenin inhibitor XAV939, suggesting that WEE1 acts via the Wnt/β-catenin signaling pathway. Conclusion Our study demonstrates that WEE1 promotes ESC migration and fibrosis via the Wnt/β-catenin signaling pathway. Thus, WEE1 may serve as a potential therapeutic target for the treatment of endometriosis.

Transcriptional Profiling of Macrophages Reveals Distinct Parasite Stage-driven Signatures During Early Infection by Leishmania Donovani

Macrophages undergo swift changes in mRNA abundance upon pathogen invasion. Herein we describe early remodelling of the macrophage transcriptome during infection by amastigotes or promastigotes of Leishmania donovani. Approximately 10% - 16% of host mRNAs were differentially modulated in L. donovani-infected macrophages when compared to uninfected controls. This response was partially stage-specific as a third of changes in mRNA abundance were either exclusively driven by one of the parasite forms or significantly different between them. Gene ontology analyses identified categories associated with immune functions (e.g. antigen presentation and leukocyte activation) among significantly downregulated mRNAs while cytoprotective-related categories (e.g. DNA repair and apoptosis inhibition) were enriched in upregulated transcripts during amastigote infection. Interestingly a combination of upregulated (e.g. cellular response to IFNβ) and repressed (e.g. leukocyte activation, chemotaxis) immune-related transcripts were overrepresented in the promastigote-infected dataset. In addition, Ingenuity Pathway Analysis (IPA®) coupled specific mRNA subsets with a number of upstream transcriptional regulators predicted to be modulated in macrophages infected with L. donovani amastigotes (e.g. STAT1 inhibition) or promastigotes (e.g. NRF2, IRF3, and IRF7 activation). Overall, our results indicate that early parasite stage-driven transcriptional remodelling in macrophages contributes to orchestrate both protective and deleterious host cell responses during L. donovani infection.

Methylmercury Induced Apoptosis of Human Neuroblastoma Cells Through the ROS Mediated Caspase and PARP/AIF Dependent Pathways

Methylmercury (MeHg) is an environmental neurotoxic substance, which can be absorbed by the human body through the digestive tract, and easily cross the blood-brain barrier, causing irreversible damage to the human central nervous system. Reactive oxygen species (ROS) are involved in various ways of intracellular physiological or pathological processes including neuronal apoptosis. The current studies attempted to explore the role of ROS-mediated PARP/AIF apoptosis signal in the process of MeHg inducing human neuroblastoma cells (SH-SY5Y) death. Here, the present studies found that SH-SY5Y cells underwent apoptosis in response to MeHg, which was accompanied by increased the levels of ROS and calcium ion, and the activation of caspase cascades and poly ADP-ribose polymerase (PARP). The decrease in ROS levels significantly reduced the expression of these proteins and the rate of apoptosis. Inhibition of caspase pathway can reduce the rate of apoptosis, but can not prevent the occurrence of apoptosis. Furthermore, inhibition of PARP signaling can significantly reduce the apoptosis rate and the expression of caspase pathway related proteins. Collectively, these results indicated that ROS mediated activation of caspase pathway and PARP /AIF signaling pathway are involved in MeHg induced apoptosis, and there is a certain relationship between the two pathways.

Identification and validation of E3 ubiquitin ligase XIAP as a novel substrate of deubiquitinase USP7 (HAUSP) - Implication towards oncogenesis

The induction of apoptosis upon USP7 (HAUSP) inhibition is established in cancers that contain a wild-type p53 (p53Wt) through the USP7-Mdm2-p53 axis, but no clear explanation has yet been reported for the same to occur in cancers containing mutant 53 (p53Mut) or even p53 null (p53Null) systems. Instead of this USP7-Mdm2-p53 axis USP7 also works through an alternative new pathway identified in this study. Here in this study, we observed that the magnitude of apoptosis induction in response to USP7 inhibition was remarkably similar between cancer cells showing p53Null or p53Mut and those with p53Wt. Through a proteomics-based approach, we were able to identify XIAP as a novel interacting partner for USP7. XIAP is a potent and well-characterized member of the inhibitor of apoptosis proteins (IAPs), which function through caspase inhibition. We successfully identified USP7 as a positive regulator of XIAP at post-translational but not at its transcriptional level. Using molecular modelling coupled with domain deletion studies, we show that the first three Ubl domains in association with the catalytic domain of USP7 interact with the BIR2 and the linker region between BIR2 and BIR3 domains of XIAP. Modulation of expression and catalytic activity of USP7 in multiple type of cancer cell lines showed that USP7 stabilizes XIAP through its deubiquitinase activity. We have also observed that USP7 sensitizes cells against chemotherapeutic drugs through stabilization of XIAP. Thus, USP7 promotes tumorigenesis in multiple cancers, via stabilization of XIAP that results in apoptosis inhibition in caspase dependent pathway. Moreover, we observed that combinatorial inhibition of USP7 and XIAP can induce cellular apoptosis in a higher magnitude than their individual inhibition. Additionally, our results indicates that nanoformulated P5091 and P22077 showed higher potency for killing C6 cells in comparison to normal drugs. To the best of our knowledge, this is the first report on identification and validation of XIAP, a crucial E3 ubiquitin ligase, as a novel substrate of the deubiquitinase USP7 and they together involve in empowerment of the tumorigenic potential of cancer cells.

Mesenchymal stem cell-derived extracellular vesicles prevent the development of osteoarthritis via the circHIPK3/miR-124-3p/MYH9 axis

Background Extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) may play a vital role in a variety of biological processes, including cartilage regeneration. However, few studies reported their potential in the development of osteoarthritis (OA) previously. In this study, we explored the biological roles and underlying mechanism of MSCs-EVs in OA. Results Co-culture experiments revealed that MSCs-EVs could promote the expression of collagen type II alpha 1 chain (COL2A1), SRY-box transcription factor 9 (SOX9) and Aggrecan while negatively regulate the expression of chondrocyte hypertrophy markers matrix metallopeptidase 13 (MMP-13) and RUNX family transcription factor 2 (Runx2) in mouse chondrocytes in the OA model. Besides, the results of cell experiments indicated that MSCs-EVs could notably weaken the suppression of chondrocyte proliferation, migration and the promotion of chondrocyte apoptosis via interleukin1β (IL-1β) induction. In addition, MSCs-circHIPK3-EVs (EVs derived from MSCs overexpressing circHIPK3) considerably improved IL-1β-induced chondrocyte injury. Mechanistically, we elucidated that circHIPK3 could directly bind to miR-124-3p and subsequently elevate the expression of the target gene MYH9. Conclusion The findings in our study demonstrated that EVs-circHIPK3 participated in MSCs-EVs-mediated chondrocyte proliferation and migration induction and in chondrocyte apoptosis inhibition via the miR-124-3p/MYH9 axis. This offers a promising novel cell-free therapy for treating OA. Graphic abstract

Polysaccharides with Antitumor Effect in Breast Cancer: A Systematic Review of Non-Clinical Studies

Purpose: To review the effects of polysaccharides and their proposed mechanisms of action in breast cancer experimental models. Data sources, selection, and extraction: Articles were selected by using PubMed, ScienceDirect, Scopus, and Medline, assessed from 1 May 2019 to 1 July 2020. The systematic review was registered in the International Prospective Register of Systematic Reviews (Prospero) under the number CRD42020169103. Results: Most of the studies explore algae polysaccharides (43.2%), followed by mushrooms (13.5%), plants (13.5%), fruits (10.8%), fungus (2.7%), bacteria, (2.7%), and sea animals (2.7%). A total of 8.1% investigated only in vitro models, 62.1% evaluated only in vivo models, and 29.7% evaluated in vitro and in vivo models. The mechanism of action involves apoptosis, inhibition of cellular proliferation, angiogenesis, and antimetastatic effects through multiple pathways. Conclusions: Findings included here support further investigations on the anti-tumor effect of polysaccharides. Some polysaccharides, such as fucoidan and β-glucans, deserve detailed and structured studies aiming at translational research on breast tumors, since they are already used in the clinical practice of other proposals of human health.