Prohibitin protects proximal tubule epithelial cells against oxidative injury through mitochondrial pathways

Rosmarinic acid ameliorated oxidative stress, neuronal injuries, and mitochondrial dysfunctions mediated by polyglutamine and ɑ-synuclein in Caenorhabditis elegans models

Numerous natural antioxidants have been developed into agents for neurodegenerative diseases (NDs) treatment. Rosmarinic acid (RA), an excellent antioxidant, exhibits neuroprotective activity, but its anti-NDs efficacy remains puzzling. Here, Caenorhabditis elegans models were employed to systematically reveal RA-mediated mechanisms in delaying NDs from diverse facets, including oxidative stress, the homeostasis of neural and protein, and mitochondrial disorders. Firstly, RA significantly inhibited reactive oxygen species accumulation, reduced peroxide malonaldehyde production, and strengthened the antioxidant defense system via increasing superoxide dismutase activity. Besides, RA reduced neuronal loss and ameliorated polyglutamine and ɑ-synuclein-mediated dyskinesia in NDs models. Further, in combination with the data and molecular docking results, RA may bind specifically to Huntington protein and ɑ-synuclein to prevent toxic protein aggregation and thus enhance proteostasis. Finally, RA ameliorated mitochondrial dysfunction including increasing adenosine triphosphate and mitochondrial membrane potential levels and rescuing mitochondrial membrane proteins' expressions and mitochondrial structural abnormalities via regulating mitochondrial dynamics genes and improving the mitochondrial kinetic homeostasis. Thus, this study systematically revealed the RA-mediated neuroprotective mechanism and promoted RA as a promising nutritional intervention strategy to prevent NDs.

The Effect of Prohibitins on Mitochondrial Function during Octopus tankahkeei Spermiogenesis

Mitochondria are essential for spermiogenesis. Prohibitins (PHBs; prohibitin 1, PHB1 or PHB, and prohibitin 2, PHB2) are evolutionarily conserved and ubiquitously expressed mitochondrial proteins that act as scaffolds in the inner mitochondrial membrane. In this study, we analyzed the molecular structure and dynamic expression characteristics of Ot-PHBs, observed the colocalization of Ot-PHB1 with mitochondria and polyubiquitin, and studied the effect of phb1 knockdown on mitochondrial DNA (mtDNA) content, reactive oxygen species (ROS) levels, and apoptosis-related gene expression in spermatids. Our aim was to explore the effect of Ot-PHBs on mitochondrial function during the spermiogenesis of Octopus tankahkeei (O. tankahkeei), an economically important species in China. The predicted Ot-PHB1/PHB2 proteins contained an N-terminal transmembrane, a stomatin/prohibitin/flotillin/HflK/C (SPFH) domain (also known as the prohibitin domain), and a C-terminal coiled-coil domain. Ot-phb1/phb2 mRNA were widely expressed in the different tissues, with elevated expression in the testis. Further, Ot-PHB1 and Ot-PHB2 were highly colocalized, suggesting that they may function primarily as an Ot-PHB compiex in O. tankahkeei. Ot-PHB1 proteins were mainly expressed and localized in mitochondria during spermiogenesis, implying that their function may be localized to the mitochondria. In addition, Ot-PHB1 was colocalized with polyubiquitin during spermiogenesis, suggesting that it may be a polyubiquitin substrate that regulates mitochondrial ubiquitination during spermiogenesis to ensure mitochondrial quality. To further investigate the effect of Ot-PHBs on mitochondrial function, we knocked down Ot-phb1 and observed a decrease in mtDNA content, along with increases in ROS levels and the expressions of mitochondria-induced apoptosis-related genes bax, bcl2, and caspase-3 mRNA. These findings indicate that PHBs might influence mitochondrial function by maintaining mtDNA content and stabilizing ROS levels; in addition, PHBs might affect spermatocyte survival by regulating mitochondria-induced apoptosis during spermiogenesis in O. tankahkeei.

LPLUNC1 reduces glycolysis in nasopharyngeal carcinoma cells through the PHB1-p53/c-Myc axis

Cancer cells prefer glycolysis to support their proliferation. Our previous studies have shown that the long palate, lung, and nasal epithelial cell clone 1 (LPLUNC1) can upregulate prohibitin 1 (PHB1) expression to inhibit the proliferation of nasopharyngeal carcinoma (NPC) cells. Given that PHB1 is an important regulator of cell energy metabolism, we explored whether and how LPLUNC1 regulated glucose glycolysis in NPC cells. LPLUNC1 or PHB1 overexpression decreased glycolysis and increased oxidative phosphorylation (OXPHOS)-related protein expression in NPC cells, promoting phosphorylated PHB1 nuclear translocation through 14-3-3σ. LPLUNC1 overexpression also increased p53 but decreased c-Myc expression in NPC cells, which were crucial for the decrease in glycolysis and increase in OXPHOS-related protein expression induced by LPLUNC1 overexpression. Finally, we found that treatment with all-trans retinoic acid (ATRA) reduced the viability and clonogenicity of NPC cells, decreased glycolysis, and increased OXPHOS-related protein expression by enhancing LPLUNC1 expression in NPC cells. Therefore, the LPLUNC1-PHB1-p53/c-Myc axis decreased glycolysis in NPC cells, and ATRA upregulated LPLUNC1 expression, ATRA maybe a promising drug for the treatment of NPC.

Oxidative Stress and Mitochondrial Dysfunction in Chronic Kidney Disease

The kidney contains many mitochondria that generate ATP to provide energy for cellular processes. Oxidative stress injury can be caused by impaired mitochondria with excessive levels of reactive oxygen species. Accumulating evidence has indicated a relationship between oxidative stress and kidney diseases, and revealed new insights into mitochondria-targeted therapeutics for renal injury. Improving mitochondrial homeostasis, increasing mitochondrial biogenesis, and balancing mitochondrial turnover has the potential to protect renal function against oxidative stress. Although there are some reviews that addressed this issue, the articles summarizing the relationship between mitochondria-targeted effects and the risk factors of renal failure are still few. In this review, we integrate recent studies on oxidative stress and mitochondrial function in kidney diseases, especially chronic kidney disease. We organized the causes and risk factors of oxidative stress in the kidneys based in their mitochondria-targeted effects. This review also listed the possible candidates for clinical therapeutics of kidney diseases by modulating mitochondrial function.

IRF1/ZNF350/GPX4-mediated ferroptosis of renal tubular epithelial cells promote chronic renal allograft interstitial fibrosis

Renal interstitial fibrosis and tubular atrophy are essential pathological characteristics of chronic renal allograft dysfunction (CAD). Herein, we revealed that ferroptosis of renal tubular epithelial cells (RTECs) might contribute to renal tubular injury in CAD. Mechanistically, TNF-α induced ferroptosis by inhibiting GPX4 transcription through upregulating IRF1 in RTECs. IRF1 could bind with ZNF350 to form a transcription factor complex, which directly binds to the GPX4 promoter region to inhibit GPX4 transcription. Ferroptotic RTECs might secrete profibrotic factors, including PDGF-BB and IL-6, to activate neighboring fibroblasts to transform into myofibroblasts or induce EMT in adjacent RTECs. In conclusion, our results confirmed a novel role of ferroptosis in renal tubular injury and interstitial fibrosis, thereby providing insights into the pathogenesis of chronic renal allograft interstitial fibrosis during CAD.

Prohibitin Protects Pulmonary Microvascular Endothelial Cells Against Cigarette Smoke Extract-Induced Cell Apoptosis and Inflammation

Background

Prohibitin has been identified to play roles in cell survival and apoptosis. Here, this study aimed to clarify the role of prohibitin in cigarette smoke extract (CSE)-induced endothelial cell apoptosis.

Methods

The protein level of prohibitin was assessed by Western blot in lung tissues from emphysema and control mice. CSE-induced human pulmonary microvascular endothelial cells (hPMECs) were applied to mimic smoke-related cell apoptosis in vitro. Prohibitin was overexpressed in hPMECs with or without CSE. Mitochondrial function was analyzed by JC-1 staining and ATP assay kits. Oxidative stress was assessed by flow cytometry, fluorescence staining and immunocytochemistry. Apoptosis was analyzed by flow cytometry, Western blot and caspase-3 activity assays. In addition, the expression of inflammatory markers was assessed by Western blot and real-time polymerase chain reaction (PCR). The secretion of inflammatory cytokines was measured by ELISA.

Results

Prohibitin was downregulated in emphysema mouse tissues compared with control experiments. Consistently, CSE inhibited both the protein and RNA levels of prohibitin in hPMECs in a dose-dependent manner. Gain-of-function experiments indicated that CSE induced collapse of mitochondrial membrane potential (MMP) and loss of ATP, while prohibitin improved mitochondrial function. CSE induced robust ROS production and oxidative DNA damage, while prohibitin decreased this damage. Upregulation of prohibitin protected the apoptosis of hPMECs from CSE. Overexpression of prohibitin significantly reduced the levels of the main proinflammatory cytokines. Finally, prohibitin inhibited nuclear factor-kappa B (NF-κB) p65 accumulation and IκBα degradation induced by CSE.

Conclusion

The current findings suggest that CSE-mediated mitochondrial dysfunction, oxidative stress, cell apoptosis and inflammation in hPMECs were reduced by overexpression of prohibitin. We identified prohibitin as a novel regulator of endothelial cell apoptosis and survival in the context of CSE exposure.

Characterisation, expression and possible functions of prohibitin during spermatogenesis in the silver pomfret Pampus argenteus

Mitochondria play an important role in spermatogenesis, and some mitochondrial proteins are specifically related to this process. In this study we investigated the cytological characteristics of spermatogenic cells, including mitochondrial dynamics, during spermatogenesis in Pampus argenteus. In addition, we characterised the mitochondria-related protein prohibitin (PHB), which has been reported to play roles in mitochondrial dynamics and animal fertility. The full-length cDNA of the P. argenteus phb gene (Pa-phb) is 1687bp, including a 102-bp 5'-untranslated region (UTR), a 772-bp 3'-UTR and an 813-bp open reading frame encoding 271 amino acids. The predicted P. argenteus PHB protein (Pa-PHB) contains three functional domains (a transmembrane domain, an SPFH domain (the conserved region of stomatins, prohibitins, flotillins and HflK/C) and a coiled-coil domain) and exhibits high similarity with its homologue in other animals. The Pa-phb gene was widely expressed in all tissues examined, especially the liver and heart. We primarily focused on Pa-phb expression during spermatogenesis after observing the cytological features of male germ cells, and found that Pa-phb transcripts were detected throughout the course of development of male germ cells. Notably, we observed colocalised signals of Pa-PHB and mitochondria, which were distributed in the cytoplasm around the nucleus in spermatogonia, spermatocytes and early spermatids, tended to move to one side of the cell in middle spermatids and, finally, were colocalised in the sperm midpiece. These observations indicate that Pa-PHB is primarily localised in mitochondria during spermatogenesis, indicating that it has a role in mitochondria. Based on the results of this and previous studies regarding the essential roles of PHB in mitochondria and spermatogenesis in animals, we propose a functional model for PHB during spermatogenesis, including possible roles in the proliferation of spermatogonia and in the regulation of mitochondrial morphology and function in spermatogenic cells.

Involvement of miR-27a-3p in diabetic nephropathy via affecting renal fibrosis, mitochondrial dysfunction, and endoplasmic reticulum stress

Diabetic nephropathy (DN) is acknowledged as a serious chronic complication of diabetes mellitus. Nevertheless, its pathogenesis is complicated and unclear. Thus, in this study, the role of miR-27a-3p-prohibitin/TMBIM6 signaling axis in the progression of DN was elucidated. Type 2 diabetic db/db mice and high glucose (HG)-challenged HK-2 cells were used as in vivo and in vitro models. Our results showed that miR-27a-3p was upregulated and prohibitin or transmembrane BAX inhibitor motif containing 6 (TMBIM6) was downregulated in the kidney tissues of db/db mice and HG-treated HK-2 cells. Silencing miR-27a-3p enhanced the expression of prohibitin and TMBIM6 in the kidney tissues and HK-2 cells. Inhibition of miR-27a-3p improved functional injury, as evidenced by decreased blood glucose, urinary albumin, serum creatinine, and blood urea nitrogen levels. MiR-27a-3p silencing ameliorated renal fibrosis, reflected by reduced profibrogenic genes (e.g., transforming growth factor β1, fibronectin, collagen I and III, and α-smooth muscle actin). Furthermore, inhibition of miR-27a-3p relieved mitochondrial dysfunction in the kidney of db/db mice, including upregulation of mitochondrial membrane potential, complex I and III activities, adenosine triphosphate, and mitochondrial cytochrome C, as well as suppressing reactive oxygen species production. In addition, miR-27a-3p silencing attenuated endoplasmic reticulum (ER) stress, reflected by reduced expression of p-IRE1α, p-eIF2α, XBP1s, and CHOP. Mechanically, we identified prohibitin and TMBIM6 as direct targets of miR-27a-3p. Inhibition of miR-27a-3p protected HG-treated HK-2 cells from apoptosis, extracellular matrix accumulation, mitochondrial dysfunction, and ER stress by regulating prohibitin or TMBIM6. Taken together, we reveal that miR-27a-3p-prohibitin/TMBIM6 signaling axis regulates the progression of DN, which can be a potential therapeutic target.

Circulating levels of mitochondrial uncoupling protein 2, but not prohibitin, are lower in humans with type 2 diabetes and correlate with brachial artery flow-mediated dilation

BACKGROUND

Excessive reactive oxygen species from endothelial mitochondria in type 2 diabetes individuals (T2DM) may occur through multiple related mechanisms, including production of mitochondrial reactive oxygen species (mtROS), inner mitochondrial membrane (Δψ_m) hyperpolarization, changes in mitochondrial mass and membrane composition, and fission of the mitochondrial networks. Inner mitochondrial membrane proteins uncoupling protein-2 (UCP2) and prohibitin (PHB) can favorably impact mtROS and mitochondrial membrane potential (Δψ_m). Circulating levels of UCP2 and PHB could potentially serve as biomarker surrogates for vascular health in patients with and without T2DM.

METHODS

Plasma samples and data from a total of 107 individuals with (N = 52) and without T2DM (N = 55) were included in this study. Brachial artery flow mediated dilation (FMD) was measured by ultrasound. ELISA was performed to measure serum concentrations of PHB1 and UCP2. Mitochondrial membrane potential was measured from isolated leukocytes using JC-1 dye.

RESULTS

Serum UCP2 levels were significantly lower in T2DM subjects compared to control subjects (3.01 ± 0.34 vs. 4.11 ± 0.41 ng/mL, P = 0.04). There were no significant differences in levels of serum PHB. UCP2 levels significantly and positively correlated with FMDmm (r = 0.30, P = 0.03) in T2DM subjects only and remained significant after multivariable adjustment. Within T2DM subjects, serum PHB levels were significantly and negatively correlated with UCP2 levels (ρ = - 0.35, P = 0.03).

CONCLUSION

Circulating UCP2 levels are lower in T2DM patients and correlate with endothelium-dependent vasodilation in conduit vessels. UCP2 could be biomarker surrogate for overall vascular health in patients with T2DM and merits additional investigation.

Crosstalk Between Connexin32 and Mitochondrial Apoptotic Signaling Pathway Plays a Pivotal Role in Renal Ischemia Reperfusion-Induced Acute Kidney Injury

Aims: Perioperative acute kidney injury (AKI) resulting from renal ischemia reperfusion (IR) is not conducive to the postoperative surgical recovery. Our previous study demonstrated that reactive oxygen species (ROS) transmitted by gap junction (GJ) composed of connexin32 (Cx32) contributed to AKI. However, the precise underlying pathophysiologic mechanisms were largely unknown. This study focuses on the underlying mechanisms related to ROS transmitted by Cx32 responsible for AKI aggravation. Results: In a set of in vivo studies, renal IR was found to cause severe impairment in renal tissues with massive ROS generation, which occurred contemporaneously with activation of NF-κB/p53/p53 upregulated modulator of apoptosis (PUMA)-mediated mitochondrial apoptosis pathways. Cx32 deficiency alleviated renal IR-induced AKI, and simultaneously attenuated ROS generation and distribution in renal tissues, which further inhibited NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathways. Correspondingly, in a set of in vitro studies, hypoxia reoxygenation (HR)-induced cellular injury, and cell apoptosis in both human kidney tubular epithelial cells (HK-2s) and rat kidney tubular epithelial cells (NRK52Es) were significantly attenuated by Cx32 inhibitors or Cx32 gene knockdown. More importantly, Cx32 inhibition not only decreased ROS generation and distribution in human or rat kidney tubular epithelial cells but also inhibited its downstream NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathway activation. Innovation and Conclusion: This is the first identification of the underlying mechanisms of IR-induced renal injury integrally which demonstrates the critical role played by Cx32 in IR-induced AKI. Moreover, GJ composed of Cx32 manipulates ROS generation and distribution between neighboring cells, and alters activation of NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathways. Both inhibiting Cx32 function and scavenging ROS effectively reduce mitochondrial apoptosis and subsequently attenuate AKI, providing effective strategies for kidney protection.

Exosomes from Human Umbilical Cord Mesenchymal Stem Cells Reduce Damage from Oxidative Stress and the Epithelial-Mesenchymal Transition in Renal Epithelial Cells Exposed to Oxalate and Calcium Oxalate Monohydrate

Objective

To investigate whether exosomes from human umbilical cord mesenchymal stem cells (hUC-MSCs) can protect against the toxic effects of oxalate and calcium oxalate monohydrate (COM) crystals in human proximal tubular epithelial (HK-2) cells.

Methods

Exosomes were isolated from hUC-MSCs, purified by ultracentrifugation, and verified by examination of cell morphology using transmission electron microscopy and the presence of specific biomarkers. HK-2 cells received 1 of 4 treatments: control (cells alone), hUC-MSC exosomes, oxalate+COM, or oxalate+COM and hUC-MSC exosomes. Cell viability was determined using the MTT assay. Oxidative stress was determined by measuring LDH activity and the levels of H₂O₂, malondialdehyde (MDA), and reactive oxygen species (ROS). Expressions of N-cadherin, TGF-β, and ZO-1 were determined by immunofluorescence. Expressions of epithelial markers, mesenchymal markers, and related signaling pathway proteins were determined by western blotting.

Results

After 48 h, cells in the oxalate+COM group lost their adhesion, appeared long, spindle-shaped, and scattered, and the number of cells had significantly decreased. The oxalate+COM treatment also upregulated TGF-β and mesenchymal markers, downregulated epithelial markers, increased the levels of LDH, H₂O₂, MDA, and ROS, decreased cell viability, and increased cell migration. The isolated exosomes had double-layer membranes, had hollow, circular, or elliptical shapes, had diameters mostly between 30 and 100 nm, and expressed CD9, CD63, and Alix. Treatment of HK-2 cells with hUC-MSC exosomes reversed or partly reversed all the effects of oxalate+COM.

Conclusions

Exosomes from hUC-MSCs alleviate the oxidative injury and the epithelial-mesenchymal transformation of HK-2 cells that is induced by oxalate+COM.

A differential expression of uncoupling protein-2 associates with renal damage in stroke-resistant spontaneously hypertensive rat/stroke-prone spontaneously hypertensive rat-derived stroke congenic lines

OBJECTIVES

Uncoupling protein-2 (UCP2), a mitochondrial anion transporter involved in mitochondrial uncoupling, limiting reactive oxygen species formation, is significantly downregulated in kidneys of high-salt-fed stroke-prone spontaneously hypertensive rat (SHRSP), where it associates with increased renal damage occurrence.

METHODS

We aimed at establishing whether UCP2 differential expression associates with renal damage in two stroke-resistant spontaneously hypertensive rat (SHRSR)/SHRSP-derived stroke congenic lines. For this purpose, SHRSR, SHRSP, and two reciprocal stroke congenic lines carrying the (D1Rat134-Mt1pa) segment of chromosome 1 were fed with Japanese style diet for 8 weeks. At 4, 6, and 8 weeks of Japanese diet, kidneys were removed and analyzed for UCP2 gene and protein expression [UCP2 maps within (D1Rat134-Mt1pa)]; nuclear factor kappa-light-chain-enhancer of activated B cells protein expression; oxidized total protein levels; mitochondrial function; gene expression of cubulin, megalin, and nephrin. At 6 and 8 weeks of Japanese diet, histological damage and percentage of high molecular weight urinary proteins excretion were assessed.

RESULTS

Introgression of UCP2 in the SHRSP configuration within the SHRSR genome led to UCP2 downregulation upon Japanese diet, as compared with the SHRSR, with significantly reduced ATP levels, increased rate of inflammation, oxidative stress, renal damage, and excretion of high molecular weight proteins. The opposite phenomena were observed in the reciprocal congenic line, compared with the SHRSP. In vitro, high-NaCl medium led to UCP2 downregulation, increased apoptosis/necrosis, and reduced viability in primary renal proximal tubular epithelial cells isolated from SHRSP. Exposure of the SHRSP/proximal tubular epithelial cells to recombinant UCP2 rescued the high-salt-dependent deleterious effects.

CONCLUSION

A differential UCP2 expression associates with different degree of renal damage upon Japanese diet in two SHRSR/SHRSP-derived stroke congenic lines through modulation of mitochondrial function, inflammation, and oxidative stress.

Prohibitin: a potential therapeutic target in tyrosine kinase signaling

Prohibitin is a pleiotropic protein that has roles in fundamental cellular processes, such as cellular proliferation and mitochondrial housekeeping, and in cell- or tissue-specific functions, such as adipogenesis and immune cell functions. The different functions of prohibitin are mediated by its cell compartment-specific attributes, which include acting as an adaptor molecule in membrane signaling, a scaffolding protein in mitochondria, and a transcriptional co-regulator in the nucleus. However, the precise relationship between its distinct cellular localization and diverse functions remain largely unknown. Accumulating evidence suggests that the phosphorylation of prohibitin plays a role in a number of cell signaling pathways and in intracellular trafficking. Herein, we discuss the known and potential importance of the site-specific phosphorylation of prohibitin in regulating these features. We will discuss this in the context of new evidence from tissue-specific transgenic mouse models of prohibitin, including a mutant prohibitin lacking a crucial tyrosine phosphorylation site. We conclude with the opinion that prohibitin can be used as a potential target for tyrosine kinase signal transduction-targeting therapy, including in insulin, growth factors, and immune signaling pathways.

Retinoic acid receptors α and γ are involved in antioxidative protection in renal tubular epithelial cells injury induced by hypoxia/reoxygenation

Renal interstitial fibrosis (RIF) is a common outcome in various chronic kidney diseases. Injury to renal tubular epithelial cell (RTEC) is major link in RIF. Hypoxia is one of the common factors for RTEC damage. Retinoic acid receptors (RARs), RARα, RARβ and RARγ, are evolutionary conserved and pleiotropic proteins that have been involved in various cellular functions, including proliferation, differentiation, apoptosis, and transcription. Recently, we discovered that aberrant expression of RARs was involved in the development of RIF in rats. Here, we investigated the role of RARs in the hypoxia/reoxygenation (HR) damage model in RTEC with virus-based delivery vectors to knockdown or overexpress RARs. Relevant indicators were detected. Our results showed that HR inhibited RARα and RARγ expressions in a time-dependent manner in RTECs; however, the expression of RARβ was not changed obviously. RARα and RARγ overexpression could protect cells from oxidative stress-induced injury by inhibiting HR-induced intracellular superoxide anion (O2-) generation, cell viability and mitochondria membrane potential (MMP) decrease and transforming growth factor β1 (TGF-β1) expression and promoting endogenous antioxidant defense components, superoxide dismutase (SOD) and glutathione (GSH). Meanwhile, inhibition of RARα and RARγ expressions by small interference RNAs (siRNA) resulted in a less resistance of RTEC to HR as shown in increased O2- production and TGF-β1 expression and decreased cell viability, MMP, SOD and GSH levels. These data indicates that RARα and RARγ act as positive regulators to offset oxidative damage and profibrosis cytokine accumulation and therefore has an antioxidative effect.

Molecular characterization and function of the Prohibitin2 gene in Litopenaeus vannamei responses to Vibrio alginolyticus

Prohibitin2 (PHB2), a potential tumor suppressor protein, plays important roles in inhibition of cell cycle progression, transcriptional regulation, apoptosis and the mitochondrial respiratory chain. To explore its potential roles in crustaceans' immune responses we have identified and characterized LvPHB2, a 891 bp gene encoding a 297 amino acids protein in the shrimp Litopenaeus vannamei. Expression analyses showed that LvPHB2 is expressed in all examined tissues, and largely present in cytoplasm, correlating with its known anti-oxidation function in mitochondria. Luciferase reporter assays showed that over-expression of LvPHB2 could activate the p53 pathway, indicating that it might participate in apoptosis regulation. Quantitative real-time PCR revealed that infection with Vibrio alginolyticus induces its up-regulation in hepatopancreas. Moreover, RNAi knock-down of LvPHB2 in vivo raises mortality rates of L. vannamei infected by V. alginolyticus, and affects expression of STAT3, Caspase3 and p53 genes. We found significantly higher reactive oxygen species production, DNA damage and apoptosis rates in LvPHB2-silenced shrimp challenged with V. alginolyticus than in controls injected with a Green Fluorescent Protein-silencing construct. Our results suggest that LvPHB2 plays a vital role in shrimp responses to V. alginolyticus infection through its participation in regulation of oxidants and apoptosis.

Infection with Plasmodium berghei ookinetes alters protein expression in the brain of Anopheles albimanus mosquitoes

Background

The behaviour of Anopheles spp. mosquitoes, vectors for Plasmodium parasites, plays a crucial role in the propagation of malaria to humans. Consequently, it is important to understand how the behaviour of these mosquitoes is influenced by the interaction between the brain and immunological status. The nervous system is intimately linked to the immune and endocrine systems. There is evidence that the malaria parasite alters the function of these systems upon infecting the mosquito. Although there is a complex molecular interplay between the Plasmodium parasite and Anopheles mosquito, little is known about the neuronal alteration triggered by the parasite invasion. The aim of this study was to analyse the modification of the proteomic profile in the An. albimanus brain during the early phase of the Plasmodium berghei invasion.

Results

At 24 hours of the P. berghei invasion, the mosquito brain showed an increase in the concentration of proteins involved in the cellular metabolic pathway, such as ATP synthase complex alpha and beta, malate dehydrogenase, alanine transaminase, enolase and vacuolar ATP synthase. There was also a rise in the levels of proteins with neuronal function, such as calreticulin, mitofilin and creatine kinase. Concomitantly, the parasite invasion repressed the expression of synapse-associated proteins, including enolyl CoA hydratase, HSP70 and ribosomal S60 proteins.

Conclusions

Identification of upregulated and downregulated protein expression in the mosquito brain 24 hours after Plasmodium invaded the insect midgut paves the way to better understanding the regulation of the neuro-endocrine-immune system in an insect model during parasite infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1830-9) contains supplementary material, which is available to authorized users.

A novel prohibitin-binding compound induces the mitochondrial apoptotic pathway through NOXA and BIM upregulation

We previously described diaryl trifluorothiazoline compound 1a (hereafter referred to as fluorizoline) as a first-in-class small molecule that induces p53-independent apoptosis in a wide range of tumor cell lines. Fluorizoline directly binds to prohibitin 1 and 2 (PHBs), two proteins involved in the regulation of several cellular processes, including apoptosis. Here we demonstrate that fluorizoline-induced apoptosis is mediated by PHBs, as cells depleted of these proteins are highly resistant to fluorizoline treatment. In addition, BAX and BAK are necessary for fluorizoline-induced cytotoxic effects, thereby proving that apoptosis occurs through the intrinsic pathway. Expression analysis revealed that fluorizoline induced the upregulation of Noxa and Bim mRNA levels, which was not observed in PHB-depleted MEFs. Finally, Noxa^−/−/Bim^−/− MEFs and NOXA-downregulated HeLa cells were resistant to fluorizoline-induced apoptosis. All together, these findings show that fluorizoline requires PHBs to execute the mitochondrial apoptotic pathway.

Mitochondrial Dysfunction Contributes to Hypertensive Target Organ Damage: Lessons from an Animal Model of Human Disease

Mechanisms underlying hypertensive target organ damage (TOD) are not completely understood. The pathophysiological role of mitochondrial oxidative stress, resulting from mitochondrial dysfunction, in development of TOD is unclear. The stroke-prone spontaneously hypertensive rat (SHRSP) is a suitable model of human hypertension and of its vascular consequences. Pathogenesis of TOD in SHRSP is multifactorial, being determined by high blood pressure levels, high salt/low potassium diet, and genetic factors. Accumulating evidence points to a key role of mitochondrial dysfunction in increased susceptibility to TOD development of SHRSP. Mitochondrial abnormalities were described in both heart and brain of SHRSP. Pharmacological compounds able to protect mitochondrial function exerted a significant protective effect on TOD development, independently of blood pressure levels. Through our research efforts, we discovered that two genes encoding mitochondrial proteins, one (Ndufc2) involved in OXPHOS complex I assembly and activity and the second one (UCP2) involved in clearance of mitochondrial ROS, are responsible, when dysregulated, for vascular damage in SHRSP. The suitability of SHRSP as a model of human disease represents a promising background for future translation of the experimental findings to human hypertension. Novel therapeutic strategies toward mitochondrial molecular targets may become a valuable tool for prevention and treatment of TOD in human hypertension.