Ubiquitin carboxyl-terminal hydrolase L1, a novel deubiquitinating enzyme in the vasculature, attenuates NF-kappaB activation

UCHL1 deficiency upon HCMV infection induces vascular endothelial inflammatory injury mediated by mitochondrial iron overload

Human cytomeglovirus (HCMV) infection predisposes blood vessels to atherosclerosis (AS) and post-transplantation restenosis, but the underlying molecular basis remains elusive. Here, we found that HCMV infection activates AIM2 inflammasome and pyroptosis in vascular endothelial cells by inducing mitochondrial iron overload. Mechanistically, under normal conditions, ubiquitin carboxyl terminal hydrolase-L1 (UCHL1) was identified as a DUB enzyme that interacts with, deubiquitylates, and stabilizes ferredoxin reductase (FDXR), an important mitochondrial protein that regulates mitochondral iron homeostasis. However, HCMV infection induces the aberrantly elevated m6A modification and R-loops, the three-stranded DNA-DNA:RNA hybrid structures. The expression of UCHL1 was remarkably reduced by m6A modification-mediated mRNA decay and R-loop-dependent transcriptional termination after HCMV infection. Deficiency of UCHL1 causes ubiquitination and degradation of FDXR. Loss of FDXR induces the mitochondrial iron overload, which consequently leads to AIM2 inflammasome activation and endothelial injury. Moreover, both downregulation expression of UCHL1 and related inflammatory injury in vascular endothelium was observed in MCMV-infected mice. Notably, STM2457, a METTL3 specific inhibitor, restores the expression of UCHL1 upon HCMV infection, thereby inhibiting the inflammatory injury of vascular endothelial cells. Our findings delineate a novel mechnism involved in HCMV-induced inflammatory injury to vascular endothelium and implicate the role of METTL3 inhibitor as a potential therapeutic approach.

UCHL1 Regulates Radiation Lung Injury via Sphingosine Kinase-1

GADD45a is a gene we previously reported as a mediator of responses to acute lung injury. GADD45a-/- mice express decreased Akt and increased Akt ubiquitination due to the reduced expression of UCHL1 (ubiquitin c-terminal hydrolase L1), a deubiquitinating enzyme, while GADD45a-/- mice have increased their susceptibility to radiation-induced lung injury (RILI). Separately, we have reported a role for sphingolipids in RILI, evidenced by the increased RILI susceptibility of SphK1-/- (sphingosine kinase 1) mice. A mechanistic link between UCHL1 and sphingolipid signaling in RILI is suggested by the known polyubiquitination of SphK1. Thus, we hypothesized that the regulation of SphK1 ubiquitination by UCHL1 mediates RILI. Initially, human lung endothelial cells (EC) subjected to radiation demonstrated a significant upregulation of UCHL1 and SphK1. The ubiquitination of EC SphK1 after radiation was confirmed via the immunoprecipitation of SphK1 and Western blotting for ubiquitin. Further, EC transfected with siRNA specifically for UCHL1 or pretreated with LDN-5744, as a UCHL1 inhibitor, prior to radiation were noted to have decreased ubiquitinated SphK1 in both conditions. Further, the inhibition of UCHL1 attenuated sphingolipid-mediated EC barrier enhancement was measured by transendothelial electrical resistance. Finally, LDN pretreatment significantly augmented murine RILI severity. Our data support the fact that the regulation of SphK1 expression after radiation is mediated by UCHL1. The modulation of UCHL1 affecting sphingolipid signaling may represent a novel RILI therapeutic strategy.

BmCPV replication is suppressed by the activation of the NF-κB/autophagy pathway through the interaction of vsp21 translated by vcircRNA_000048 with ubiquitin carboxyl-terminal hydrolase

Bombyx mori cypovirus (BmCPV), a typical double-stranded RNA virus, was demonstrated to generate a viral circRNA, vcircRNA_000048, which encodes a vsp21 with 21 amino acid residues to suppress viral replication. However, the regulatory mechanism of vsp21 on virus infection remained unclear. This study discovered that vsp21 induces reactive oxygen species (ROS) generation, activates autophagy, and attenuates virus replication by inducing autophagy. Then we confirmed that the effect of vsp21-induced autophagy on viral replication was attributed to the activation of the NF-κB signaling pathway. Furthermore, we clarified that vsp21 interacted with ubiquitin carboxyl-terminal hydrolase (UCH) and that ubiquitination and degradation of phospho-IκB-α were enhanced by vsp21 via competitive binding to UCH. Finally, we validated that vsp21 activates the NF-κB/autophagy pathway to suppress viral replication by interacting with UCH. These findings provided new insights into regulating viral multiplication and reovirus-host interaction.

Ubiquitin C‑terminal hydrolase‑L1: A new cancer marker and therapeutic target with dual effects (Review)

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), a member of the lesser-known deubiquitinating enzyme family, has deubiquitinase and ubiquitin (Ub) ligase activity and the role of stabilizing Ub. UCH-L1 was first discovered in the brain and is associated with regulating cell differentiation, proliferation, transcriptional regulation and numerous other biological processes. UCH-L1 is predominantly expressed in the brain and serves a role in tumor promotion or inhibition. There is still controversy about the effect of UCH-L1 dysregulation in cancer and its mechanisms are unknown. Extensive research to investigate the mechanism of UCH-L1 in different types of cancer is key for the future treatment of UCH-L1-associated cancer. The present review details the molecular structure and function of UCH-L1. The role of UCH-L1 in different types of cancer is also summarized and how novel treatment targets provide a theoretical foundation in cancer research is discussed.

Ubiquitin C-terminal hydrolase L1 (UCHL1), a double-edged sword in mammalian oocyte maturation and spermatogenesis

BACKGROUND

Recent studies have shown that ubiquitin-mediated cell apoptosis can modulate protein interaction and involve in the progress of oocyte maturation and spermatogenesis. As one of the key regulators involved in ubiquitin signal, ubiquitin C-terminal hydrolase L1 (UCHL1) is considered a molecular marker associated with spermatogonia stem cells. However, the function of UCHL1 was wildly reported to regulate various bioecological processes, such as Parkinson's disease, lung cancer, breast cancer and colon cancer, how UCHL1 affects the mammalian reproductive system remains an open question.

METHODS

We identified papers through electronic searches of PubMed database from inception to July 2022.

RESULTS

Here, we summarize the important function of UCHL1 in controlling mammalian oocyte development, regulating spermatogenesis and inhibiting polyspermy, and we posit the balance of UCHL1 was essential to maintaining reproductive cellular and tissue homeostasis.

CONCLUSION

This study considers the 'double-edged sword' role of UCHL1 during gametogenesis and presents new insights into UCHL1 in germ cells.

UCHL1 Impairs Periodontal Ligament Stem Cell Osteogenesis in Periodontitis

Periodontitis comprises a series of inflammatory responses resulting in alveolar bone loss. The suppression of osteogenesis of periodontal ligament stem cells (PDLSCs) by inflammation is responsible for impaired alveolar bone regeneration, which remains an ongoing challenge for periodontitis therapy. Ubiquitin C-terminal hydrolase L1 (UCHL1) belongs to the family of deubiquitinating enzymes, which was found to play roles in inflammation previously. In this study, the upregulation of UCHL1 was identified in inflamed PDLSCs isolated from periodontitis patients and in healthy PDLSCs treated with tumor necrosis factor-α or interleukin-1β, and the higher expression level of UCHL1 was accompanied with the impaired osteogenesis of PDLSCs. Then UCHL1 was inhibited in PDLSCs using the lentivirus or inhibitor, and the osteogenesis of PDLSCs suppressed by inflammation was rescued by UCHL1 inhibition. Mechanistically, the negative effect of UCHL1 on the osteogenesis of PDLSCs was attributable to its negative regulation of mitophagy-dependent bone morphogenetic protein 2/Smad signaling pathway in periodontitis-associated inflammation. Furthermore, a ligature-induced murine periodontitis model was established, and the specific inhibitor of UCHL1 was administrated to periodontitis mice. The histological results showed increased active osteoblasts on alveolar bone surface and enhanced alveolar bone regeneration when UCHL1 was inhibited in periodontitis mice. Besides, the therapeutic effects of UCHL1 inhibition on ameliorating periodontitis were verified, as indicated by less bone loss and reduced inflammation. Altogether, our study proved UCHL1 to be a key negative regulator of the osteogenesis of PDLSCs in periodontitis and suggested that UCHL1 inhibition holds promise for alveolar bone regeneration in periodontitis treatment.

Novel pathophysiological roles of α-synuclein in age-related vascular endothelial dysfunction

Although α-synuclein (SNCA) is a well-known pathological molecule involved in synucleinopathy in neurons, its physiological roles remain largely unknown. We reported that serum SNCA levels have a close inverse correlation with blood pressure and age, which indicates the involvement of SNCA in age-related endothelial dysfunction. Therefore, this study aimed to elucidate the molecular functions of SNCA in the endothelium. We confirmed that SNCA was expressed in and secreted from endothelial cells (ECs). Exogenous treatment with recombinant SNCA (rSNCA) activated the Akt-eNOS axis and increased nitric oxide production in ECs. Treatment with rSNCA also suppressed TNF-α- and palmitic acid-induced NF-κB activation, leading to the suppression of VCAM-1 upregulation and restoration of eNOS downregulation in ECs. As for endogenous SNCA expression, replicative senescence resulted in the attenuation of SNCA expression in cultured ECs, similar to the effects of physiological aging on mice aortas. The siRNA-mediated silencing of SNCA consistently resulted in senescent phenotypes, such as eNOS downregulation, increased β-gal activity, decreased Sirt1 expression, and increased p53 expression, in ECs. Ex vivo assessment of endothelial functions using aortic rings revealed impaired endothelium-dependent acetylcholine-induced relaxation in SNCA knockout (KO) mice. Furthermore, SNCA KO mice, especially those on a high-fat diet, displayed elevated blood pressure compared with wild-type mice; this could be eNOS dysfunction-dependent because of the lower difference caused by L-NAME administration. These results indicate that exogenous and endogenous SNCA in ECs might physiologically maintain vascular integrity, and age-related endothelial dysfunction might be partially ascribed to loss-of-function of SNCA in ECs.

A proteomics analysis of neointima formation on decellularized vascular grafts reveals regenerative alterations in protein signature running head: Proteomics analysis of neointima formation

Background: Neointima formation contributes to vascular grafts stenosis and thrombosis. It is a complex reaction that plays a significant role in the performance of vascular grafts. Despite its critical implications, little is known about the mechanisms underlying neointima formation. This study compares neointima proteome in different stages and plasma samples.

Methods: Heterogenous acellular native arteries were implanted as abdominal aortic interposition grafts in a rabbit model. Grafts were harvested at 0.5, 1, 4, 6, 7, 14, 21, and 28 days post-surgery for histological and proteomic analysis of the neointima.

Results: Histological examination showed a transformed morphological pattern and components, including serum proteins, inflammatory cells, and regenerative cells. Proteomics analysis of the neointima showed distinct characteristics after 14 days of implantation compared to early implantation. Early changes in the neointima samples were proteins involved in acute inflammation and thrombosis, followed by the accumulation of extracellular matrix (ECM) proteins. A total of 110 proteins were found to be differentially expressed in later samples of neointima compared to early controls. The enriched pathways were mainly protein digestion and adsorption, focal adhesion, PI3K-Akt signaling pathway, and ECM-receptor interaction in the late stage. All distributions of proteins in the neointima are different compared to plasma.

Conclusion: The biological processes of neointima formation at different stages identified with proteome found developmental characteristics of vascular structure on a decellularized small vascular graft, and significant differences were identified by proteomics in the neointima of early-stage and late-stage after implantation. In the acute unstable phase, the loose and uniform neointima was mainly composed of plasma proteins and inflammatory cells. However, in the relatively stable later stage, the most notable results were an up-regulation of ECM components. The present study demonstrates an interaction between biological matter and vascular graft, provides insights into biological process changes of neointima and facilitates the construction of a functional bioengineered small vascular graft for future clinical applications.

Investigation of H2S Donor Treatment on Neutrophil Extracellular Traps in Experimental Colitis

Inflammatory bowel diseases (IBD) are chronic, immune-mediated disorders, which affect the gastrointestinal tract with intermittent ulceration. It is increasingly clear that neutrophil extracellular traps (NETs) seem to have a role in IBD; however, the associated pathogenesis is still not known. Furthermore, several conventional therapies are available against IBD, although these might have side effects. Our current study aimed to investigate the effects of hydrogen sulfide (H₂S) treatment on NETs formation and on the expression of inflammatory mediators in experimental rat colitis. To model IBD, 2,4,6-trinitrobenzenesulfonic acid (TNBS) was administered intracolonically (i.c.) to Wistar-Harlan male rats. Animals were treated (2 times/day) with H₂S donor Lawesson's reagent per os. Our results showed that H₂S treatment significantly decreased the extent of colonic lesions. Furthermore, the expression of members of NETs formation: peptidyl arginine deiminase 4 (PAD4), citrullinated histone H3 (citH3), myeloperoxidase (MPO) and inflammatory regulators, such as nuclear transcription factor-kappa B (NF-κB) and high-mobility group box 1 (HMGB1) were reduced in H₂S treated group compared to TNBS. Additionally, H₂S donor administration elevated the expression of ubiquitin C-terminal hydroxylase L1 (UCHL-1), a potential anti-inflammatory mediator. Taken together, our results showed that H₂S may exert anti-inflammatory effect through the inhibition of NETs formation, which suggests a new therapeutic approach against IBD.

The Known Unknowns: An Overview of the State of Blood-Based Protein Biomarkers of Mild Traumatic Brain Injury

Blood-based protein biomarkers have revolutionized several fields of medicine by enabling molecular level diagnosis, as well as monitoring disease progression and treatment efficacy. Traumatic brain injury (TBI) so far has benefitted only moderately from using protein biomarkers to improve injury outcome. Because of its complexity and dynamic nature, TBI, especially its most prevalent mild form (mild TBI; mTBI), presents unique challenges toward protein biomarker discovery and validation given that blood is frequently obtained and processed outside of the clinical laboratory (e.g., athletic fields, battlefield) under variable conditions. As it stands, the field of mTBI blood biomarkers faces a number of outstanding questions. Do elevated blood levels of currently used biomarkers-ubiquitin carboxy-terminal hydrolase L1, glial fibrillary acidic protein, neurofilament light chain, and tau/p-tau-truly mirror the extent of parenchymal damage? Do these different proteins represent distinct injury mechanisms? Is the blood-brain barrier a "brick wall"? What is the relationship between intra- versus extracranial values? Does prolonged elevation of blood levels reflect de novo release or extended protein half-lives? Does biological sex affect the pathobiological responses after mTBI and thus blood levels of protein biomarkers? At the practical level, it is unknown how pre-analytical variables-sample collection, preparation, handling, and stability-affect the quality and reliability of biomarker data. The ever-increasing sensitivity of assay systems and lack of quality control of samples, combined with the almost complete reliance on antibody-based assay platforms, represent important unsolved issues given that false-negative results can lead to false clinical decision making and adverse outcomes. This article serves as a commentary on the state of mTBI biomarkers and the landscape of significant challenges. We highlight and discusses several biological and methodological "known unknowns" and close with some practical recommendations.

Growth arrest and DNA damage-inducible proteins (GADD45) in psoriasis

The interplay between T cells, dendritic cells and keratinocytes is crucial for the development and maintenance of inflammation in psoriasis. GADD45 proteins mediate DNA repair in different cells including keratinocytes. In the immune system, GADD45a and GADD45b regulate the function and activation of both T lymphocytes and dendritic cells and GADD45a links DNA repair and epigenetic regulation through its demethylase activity. Here, we analyzed the expression of GADD45a and GADD45b in the skin, dendritic cells and circulating T cells in a cohort of psoriasis patients and their regulation by inflammatory signals. Thirty patients (17 male/13 female) with plaque psoriasis and 15 controls subjects (7 male/8 female), were enrolled. Psoriasis patients exhibited a lower expression of GADD45a at the epidermis but a higher expression in dermal infiltrating T cells in lesional skin. The expression of GADD45a and GADD45b was also higher in peripheral T cells from psoriasis patients, although no differences were observed in p38 activation. The expression and methylation state of the GADD45a target UCHL1 were evaluated, revealing a hypermethylation of its promoter in lesional skin compared to controls. Furthermore, reduced levels of GADD45a correlated with a lower expression UCHL1 in lesional skin. We propose that the demethylase function of GADD45a may account for its pleiotropic effects, and the complex and heterogeneous pattern of expression observed in psoriatic disease.

Long-term inhibition of UCHL1 decreases hypertension and retinopathy in spontaneously hypertensive rats

OBJECTIVE

To investigate the role of the deubiquitinase ubiquitin C-terminal hydrolase L1 (UCHL1) in hypertension and retinopathy in the spontaneously hypertensive rat (SHR).

METHODS

Wistar-Kyoto (WKY) rats and SHRs were administered the UCHL1 inhibitor LDN57444 (20 μg/kg/day) for 4 months. Pathological changes were detected with hematoxylin and eosin, immunofluorescence, and dihydroethidium staining. The mRNA and protein expression of UCHL1 were examined by real-time PCR and immunoblotting analysis.

RESULTS

At 6 months of age, SHRs showed significantly increased mRNA and protein levels of UCHL1 in the retina compared with WKY rats. Moreover, SHRs exhibited significantly increased central retinal thickness, inflammation, and reactive oxygen species production compared with WKY rats, and these effects were markedly attenuated by systemic administration of the UCHL1 inhibitor LDN57444. The beneficial effects of LDN57444 were possibly associated with reduced blood pressure and the inactivation of several signaling pathways.

CONCLUSION

UCHL1 is involved in hypertension and retinopathy in SHRs, suggesting that UCHL1 may be used as a potential therapeutic target for treating hypertensive retinopathy.

UCHL1, a deubiquitinating enzyme, regulates lung endothelial cell permeability in vitro and in vivo

Increasing evidence suggests an important role for deubiquitinating enzymes (DUBs) in modulating a variety of biological functions and diseases. We previously identified the upregulation of the DUB ubiquitin carboxyl terminal hydrolase 1 (UCHL1) in murine ventilator-induced lung injury (VILI). However, the role of UCHL1 in modulating vascular permeability, a cardinal feature of acute lung injury (ALI) in general, remains unclear. We investigated the role of UCHL1 in pulmonary endothelial cell (EC) barrier function in vitro and in vivo and examined the effects of UCHL1 on VE-cadherin and claudin-5 regulation, important adherens and tight junctional components, respectively. Measurements of transendothelial electrical resistance confirmed decreased barrier enhancement induced by hepatocyte growth factor (HGF) and increased thrombin-induced permeability in both UCHL1-silenced ECs and in ECs pretreated with LDN-57444 (LDN), a pharmacological UCHL1 inhibitor. In addition, UCHL1 knockdown (siRNA) was associated with decreased expression of VE-cadherin and claudin-5, whereas silencing of the transcription factor FoxO1 restored claudin-5 levels. Finally, UCHL1 inhibition in vivo via LDN was associated with increased VILI in a murine model. These findings support a prominent functional role of UCHL1 in regulating lung vascular permeability via alterations in adherens and tight junctions and implicate UCHL1 as an important mediator of ALI.

Ubiquitin carboxy-terminal hydrolase L1 - physiology and pathology

Ubiquitin C-terminal hydrolase 1 (UCHL1) is an enzyme unique for its multiple activity - both ligase and hydrolase. UCHL1 was first identified as an abundant protein found in the brain and testes, however its expression is not limited to the neuronal compartment. UCHL1 is also highly expressed in carcinomas of various tissue origins, including those from brain, lung, breast, kidney, colon, prostate, pancreas and mesenchymal tissues. Loss-of-function studies and an inhibitor for UCHL1 confirmed the importance of UCHL1 for cancer therapy. So far biological significance of UCHL1 was described in the following processes: spermatogenesis, oncogenesis, angiogenesis, cell proliferation and differentiation in skeletal muscle, inflammation, tissue injury, neuronal injury and neurodegeneration.

The Interplay between Antiviral Signalling and Carcinogenesis in Human Papillomavirus Infections

Human papillomaviruses (HPV) are the causative agents of the most common sexually transmitted infection worldwide. While infection is generally asymptomatic and can be cleared by the host immune system, when persistence occurs, HPV can become a risk factor for malignant transformation. Progression to cancer is actually an unintended consequence of the complex HPV life cycle. Different antiviral defence mechanisms recognize HPV early in infection, leading to the activation of the innate immune response. However, the virus has evolved several specific strategies to efficiently evade the antiviral immune signalling. Here, we review and discuss the interplay between HPV and the host cell innate immunity. We further highlight the evasion strategies developed by different HPV to escape this cellular response and focus on the correlation with HPV-induced persistence and tumorigenesis.

UCH-L1 mitigates neurotoxicity induced by ZnO particles via stabilizing the inhibitor of NF-kappa B signaling, IκB-α

Our study determined the toxic effects of zinc oxide (ZnO) particles with different diameters on dopaminergic (DA) neurons, the role of ubiquitin C-terminal hydrolase L1 (UCH-L1) for ZnO particles-induced neurotoxicity, and corresponding molecular mechanisms. We constructed an in vitro cell injury model for DA neurons to analyze the cytotoxicity of ZnO particles using SH-SY5Y cells. Following cell viability assays and flow cytometry, we found that the cytotoxicity of ZnO particles was affected by particle size, time, and dose of exposure. For example, the toxicity of ZnO particles with 50 nm or 100 nm diameter was stronger than that of ZnO particles with 1000 nm diameter. Furthermore, ZnO particles exposure resulted in a significant decrease in UCH-L1 expression in SH-SY5Y; whereas UCH-L1 overexpression led to a significant increase in cell viability and a sharp decrease in ROS level. Western blotting and adenovirus transfection found that exposure to ZnO particles with different diameters all activate the NF-κB signaling in SH-SY5Y cells; whereas UCH-L1 over-expression resulted in increased levels of IκBα, an endogenous inhibitor of NF-κB signaling pathway. ZnO particles with different diameters all induced cytotoxicity in DA neurons, which may be related to the free Zn²⁺ in the suspension. Regarding the neurotoxic effect of ZnO particles, UCH-L1 protects against and/or alleviates neuronal damage, possibly by deubiquitination of the endogenous inhibitor, IκBα, which leads to activation of NF-κB signaling. Therefore, one possible mechanism for ZnO particle-induced neurotoxicity may be mediated via the down-regulation of UCH-L1 expression in DA cells.

USP20 (Ubiquitin-Specific Protease 20) Inhibits TNF (Tumor Necrosis Factor)-Triggered Smooth Muscle Cell Inflammation and Attenuates Atherosclerosis

Objective- Signaling that activates NFκB (nuclear factor κB) in smooth muscle cells (SMCs) is integral to atherosclerosis and involves reversible ubiquitination that activates proteins downstream of proatherogenic receptors. Deubiquitination of these proteins is mediated by USP20 (ubiquitin-specific protease 20), among other deubiquitinases. We sought to determine whether USP20 activity in SMCs decreases atherosclerosis. Approach and Results- To address this question, we used male Ldlr^-/- mice without (control) or with SMC-specific expression of murine USP20 (SMC-USP20-transgenic) or its dominant-negative (DN; C154S/H643Q) mutant (SMC-DN-USP20-transgenic). Before the appearance of intimal macrophages, NFκB activation in aortic medial SMCs was greater in SMC-DN-USP20-transgenic than in control mice. After 16 weeks on a Western diet, SMC-DN-USP20-transgenic mice had 46% greater brachiocephalic artery atheroma area than control mice. Congruently, aortic atherosclerosis assessed en face was 21% greater than control in SMC-DN-USP20-transgenic mice and 13% less than control in SMC-USP20-transgenic mice. In response to TNF (tumor necrosis factor), SMCs from SMC-DN-USP20-transgenic mice showed ≈3-fold greater NFκB activation than control SMCs. Silencing USP20 in SMCs with siRNA (small interfering RNA) augmented NFκB activation by ≈50% in response to either TNF or IL-1β (interleukin-1β). Coimmunoprecipitation experiments revealed that USP20 associates with several components of the TNFR1 (TNF receptor-1) signaling pathway, including RIPK1 (receptor-interacting protein kinase 1), a critical checkpoint in TNF-induced NFκB activation and inflammation. TNF evoked ≈2-fold more RIPK1 ubiquitination in SMC-DN-USP20-transgenic than in control SMCs, and RIPK1 was deubiquitinated by purified USP20 in vitro. Conclusions- USP20 attenuates TNF- and IL-1β-evoked atherogenic signaling in SMCs, by deubiquitinating RIPK1, among other signaling intermediates.

Earliest Mechanisms of Dopaminergic Neurons Sufferance in a Novel Slow Progressing Ex Vivo Model of Parkinson Disease in Rat Organotypic Cultures of Substantia Nigra

The current treatments of Parkinson disease (PD) are ineffective mainly due to the poor understanding of the early events causing the decline of dopaminergic neurons (DOPAn). To overcome this problem, slow progressively degenerating models of PD allowing the study of the pre-clinical phase are crucial. We recreated in a short ex vivo time scale (96 h) all the features of human PD (needing dozens of years) by challenging organotypic culture of rat substantia nigra with low doses of rotenone. Thus, taking advantage of the existent knowledge, the model was used to perform a time-dependent comparative study of the principal possible causative molecular mechanisms undergoing DOPAn demise. Alteration in the redox state and inflammation started at 3 h, preceding the reduction in DOPAn number (pre-diagnosis phase). The number of DOPAn declined to levels compatible with diagnosis only at 12 h. The decline was accompanied by a persistent inflammation and redox imbalance. Significant microglia activation, apoptosis, a reduction in dopamine vesicle transporters, and the ubiquitination of misfolded protein clearance pathways were late (96 h, consequential) events. The work suggests inflammation and redox imbalance as simultaneous early mechanisms undergoing DOPAn sufferance, to be targeted for a causative treatment aimed to stop/delay PD.

Ubiquitin Carboxyl Terminal Hydrolase L1 Attenuates TNF-α-Mediated Vascular Smooth Muscle Cell Migration Through Suppression of NF-κB Activation

Ubiquitin carboxyl terminal hydrolase L1 (UCH-L1) is one of the deubiquitinating enzymes in the ubiquitin-proteasome system. It has been shown that UCH-L1 could markedly decrease neointima formation through suppressing vascular smooth muscle cell (VSMC) proliferation in the balloon-injured rat carotid. However, whether UCH-L1 plays roles in VSMC migration remains to be determined. In this study, the primary VSMCs were isolated from aortic media of rats and TNF-α to was used to induce VSMC migration. Using a modified Boyden chamber and wound healing assay, it was found that TNF-α can dose and time-dependently induce VSMC migration with a maximal effect at 10 ng/mL. Moreover, UCH-L1 expression increased gradually with the prolonged induction time at 10 ng/mL of TNF-α. UCH-L1 content in VSMC was then modulated by recombinant adenoviruses expressing UCH-L1 or RNA interference to evaluate its roles in cell migration. The results showed that over-expression of UCH-L1 attenuated VSMC migration, while knockdown of it enhanced cell migration significantly no matter whether TNF-α treatment or not. Finally, the effect of UCH-L1 on NF-κB activation was demonstrated by NF-κB nuclear translocation and DNA binding activity, and the levels of IL-6 and IL-8 in cell culture media were examined by ELISA. It was showed that UCH-L1 over-expression inhibited NF-κB activation and decrease IL-6 and IL-8 levels, while knockdown of it enhanced NF-κB activation and increase IL-6 and IL-8 levels during TNF-α treatment. These data suggest that UCH-L1 can inhibit TNF-α-induced VSMCs migration, and this kind of effect may partially due to its suppression role in NF-κB activation.

The deubiquitinating enzyme UCHL1 negatively regulates the immunosuppressive capacity and survival of multipotent mesenchymal stromal cells

It is known that proinflammatory cytokines empower multipotent mesenchymal stromal cells (MSCs) the immunosuppressive capacity to treat various inflammatory diseases. Nevertheless, how the proinflammatory cytokines modulate the immunosuppressive capacity of MSCs is poorly understood. In the present study, we identified that the deubiquitinating enzyme ubiquitin C-terminal hydrolase 1 (UCHL1) was upregulated in MSCs upon stimulation of proinflammatory cytokines IFN-γ plus TNF-α. Interestingly, through intervening UCHL1 by shRNA knockdown or its inhibitor LDN57444 or overexpression, we found that UCHL1 played a critical role in suppressing cytokines-induced inducible nitric oxide synthase expression in murine MSCs and indoleamine 2,3-dioxygenase expression in human MSCs, thereby restrained their immunosuppressive capacity. This effect of UCHL1 was attributed to the negative role in regulating NF-κB and STAT1 signaling, as exhibited by promoting NF-κB and STAT1 activation upon inhibition of UCHL1. Besides, inhibition of UCHL1 suppressed cytokines-induced MSC apoptosis via upregulation of Bcl-2. As a consequence, UCHL1-inhibited MSCs effectively alleviated concanavalin A-induced inflammatory liver injury. Therefore, our study demonstrates a novel role of UCHL1 in regulating the immunosuppressive capacity and survival of MSCs, which further affects their immunotherapy for inflammatory diseases.

Ubiquitin carboxyl-terminal hydrolases: involvement in cancer progression and clinical implications

Protein ubiquitination and deubiquitination participate in a number of biological processes, including cell growth, differentiation, transcriptional regulation, and oncogenesis. Ubiquitin C-terminal hydrolases (UCHs), a subfamily of deubiquitinating enzymes (DUBs), includes four members: UCH-L1/PGP9.5 (protein gene product 9.5), UCH-L3, UCHL5/UCH37, and BRCA1-associated protein-1 (BAP1). Recently, more attention has been paid to the relationship between the UCH family and malignancies, which play different roles in the progression of different tumors. It remains controversial whether UCHL1 is a tumor promoter or suppressor. UCHL3 and UCH37 are considered to be tumor promoters, while BAP1 is considered to be a tumor suppressor. Studies have showed that UCH enzymes influence several signaling pathways that play crucial roles in oncogenesis, tumor invasion, and migration. In addition, UCH families are associated with tumor cell sensitivity to therapeutic modalities. Here, we reviewed the roles of UCH enzymes in the development of tumors, highlighting the potential consideration of UCH enzymes as new interesting targets for the development of anticancer drugs.

The Decrease of Uch-L1 Activity Is a Common Mechanism Responsible for Aβ 42 Accumulation in Alzheimer's and Vascular Disease

Alzheimer’s disease (AD) is a multifactorial pathology causing common brain spectrum disorders in affected patients. These mixed neurological disorders not only include structural AD brain changes but also cerebrovascular lesions. The main aim of the present issue is to find the factors shared by the two pathologies. The decrease of ubiquitin C-terminal hydrolase L1 (Uch-L1), a major neuronal enzyme involved in the elimination of misfolded proteins, was observed in ischemic injury as well as in AD, but its role in the pathogenesis of AD is far to be clear. In this study we demonstrated that Uch-L1 inhibition induces BACE1 up-regulation and increases neuronal and apoptotic cell death in control as well as in transgenic AD mouse model subjected to Bengal Rose, a light-sensitive dye inducing that induces a cortical infarction through photo-activation. Under the same conditions we also found a significant activation of NF-κB. Thus, the restoration of Uch-L1 was able to completely prevent both the increase in BACE1 protein levels and the amount of cell death. Our data suggest that the Uch-L1-mediated BACE1 up-regulation could be an important mechanism responsible for Aβ peptides accumulation in vascular injury and indicate that the modulation of the activity of this enzyme could provide new therapeutic strategies in AD.

UCHL1 Regulates Melanogenesis through Controlling MITF Stability in Human Melanocytes

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is involved in many signaling pathways via the ubiquitin-proteasome system. UCHL1 is expressed in the human skin and serves as a neuronal marker; however, its functions in melanogenesis remain unknown. Here, we investigated the role of UCHL1 in melanogenesis and elucidated the underlying mechanism using human melanocytes. UCHL1 downregulation by small interfering RNA resulted in upregulation of microphthalmia-associated transcription factor (MITF), tyrosinase, dopachrome tautomerase, tyrosinase-related protein-1, and melanin. In contrast, overexpression of UCHL1 in melanocytes via adenovirus transfection led to downregulation of tyrosinase, dopachrome tautomerase, and tyrosinase-related protein-1 and decreased melanin contents. Furthermore, UCHL1 reduced the protein, but not mRNA, levels of MITF, the upstream regulator of tyrosinase, dopachrome tautomerase, and tyrosinase-related protein-1. Inhibition of de novo protein synthesis and treatment of normal human primary epidermal melanocytes with proteasome inhibitor MG132 revealed that UCHL1 negatively regulates the stability of MITF by binding to the ubiquitinated protein. Finally, overexpression of MITF via an adenovirus restored the level of melanogenesis reduced by UCHL1. Collectively, our findings indicate a role of UCHL1 in regulating skin pigmentation. Suppression of MITF activity by UCHL1 via protein degradation might aid in the development of new therapeutic approaches for melanoma or dyspigmentation disorders.

A molecular hypothesis to explain direct and inverse co-morbidities between Alzheimer's Disease, Glioblastoma and Lung cancer

Epidemiological studies indicate that patients suffering from Alzheimer’s disease have a lower risk of developing lung cancer, and suggest a higher risk of developing glioblastoma. Here we explore the molecular scenarios that might underlie direct and inverse co-morbidities between these diseases. Transcriptomic meta-analyses reveal significant numbers of genes with inverse patterns of expression in Alzheimer’s disease and lung cancer, and with similar patterns of expression in Alzheimer’s disease and glioblastoma. These observations support the existence of molecular substrates that could at least partially account for these direct and inverse co-morbidity relationships. A functional analysis of the sets of deregulated genes points to the immune system, up-regulated in both Alzheimer’s disease and glioblastoma, as a potential link between these two diseases. Mitochondrial metabolism is regulated oppositely in Alzheimer’s disease and lung cancer, indicating that it may be involved in the inverse co-morbidity between these diseases. Finally, oxidative phosphorylation is a good candidate to play a dual role by decreasing or increasing the risk of lung cancer and glioblastoma in Alzheimer’s disease.

Overexpression of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) in serum of children after thermal injury

PURPOSE

The study aims to determinate concentrations of ubiquitin C-terminal hydrolase 1 (UCHL1), which hydrolyzes amino acids from ubiquitin and cleave di-ubiquitins, in serum of children after thermal injury.

PATIENTS/METHODS

42 children scalded by hot water, managed at the Department of Pediatric Surgery, with burns in 4-20% TBSA were included into the study (age 9 months up to 14 years, mean age 2.5±1 years). Blood plasma UCHL1 concentration was assessed in 2-6h, 12-16h, 3d, 5d, and 7d after injury using surface plasmon resonance imaging biosensor. 18 healthy subjects admitted for planned surgeries served as controls.

RESULTS

The UCHL1 concentration in the blood plasma of patients with thermal injuries reached its peak 12-16h after thermal injury and slowly decreased over time, and still did not reach the normal range on the 7th day after thermal injury. Mean concentrations of UCHL1 after thermal injury were above the range measured in controls (0.12ng/ml): 2-6h after injury - 5.59ng/dl, 12-16h after injury - 9.16ng/dl, 3 days after injury - 6.94ng/dl, 5 days after 5.41ng/dl, 7 days after injury - 4.09ng/dl.

CONCLUSIONS

We observed sudden increase in the concentration of UCHL1 2-16h after thermal injury with the slow decrease in the UCHL1 concentration over the time. UCHL1 concentration was proportional to the severity of the burn. Further studies are needed to determine the mechanisms by which UCHL1 contributes to metabolic response following thermal injury.

Current status of fluid biomarkers in mild traumatic brain injury

Mild traumatic brain injury (mTBI) affects millions of people annually and is difficult to diagnose. Mild injury is insensitive to conventional imaging techniques and diagnoses are often made using subjective criteria such as self-reported symptoms. Many people who sustain a mTBI develop persistent post-concussive symptoms. Athletes and military personnel are at great risk for repeat injury which can result in second impact syndrome or chronic traumatic encephalopathy. An objective and quantifiable measure, such as a serum biomarker, is needed to aid in mTBI diagnosis, prognosis, return to play/duty assessments, and would further elucidate mTBI pathophysiology. The majority of TBI biomarker research focuses on severe TBI with few studies specific to mild injury. Most studies use a hypothesis-driven approach, screening biofluids for markers known to be associated with TBI pathophysiology. This approach has yielded limited success in identifying markers that can be used clinically, additional candidate biomarkers are needed. Innovative and unbiased methods such as proteomics, microRNA arrays, urinary screens, autoantibody identification and phage display would complement more traditional approaches to aid in the discovery of novel mTBI biomarkers.

Vascular Proteomics Reveal Novel Proteins Involved in SMC Phenotypic Change: OLR1 as a SMC Receptor Regulating Proliferation and Inflammatory Response

Neointimal hyperplasia of vascular smooth muscle cells (VSMC) plays a critical role in atherosclerotic plaque formation and in-stent restenosis, but the underlying mechanisms are still incompletely understood. We performed a proteomics study to identify novel signaling molecules organizing the VSMC hyperplasia. The differential proteomics analysis in a balloon-induced injury model of rat carotid artery revealed that the expressions of 44 proteins are changed within 3 days post injury. The combination of cellular function assays and a protein network analysis further demonstrated that 27 out of 44 proteins constitute key signaling networks orchestrating the phenotypic change of VSMC from contractile to epithelial-like synthetic. Among the list of proteins, the in vivo validation specifically revealed that six proteins (Rab15, ITR, OLR1, PDHβ, PTPε) are positive regulators for VSMC hyperplasia. In particular, the OLR1 played dual roles in the VSMC hyperplasia by directly mediating oxidized LDL-induced monocyte adhesion via NF-κB activation and by assisting the PDGF-induced proliferation/migration. Importantly, OLR1 and PDGFRβ were associated in close proximity in the plasma membrane. Thus, this study elicits the protein network organizing the phenotypic change of VSMC in the vascular injury diseases such as atherosclerosis and discovers OLR1 as a novel molecular link between the proliferative and inflammatory responses of VSMCs.

High-risk human papillomavirus targets crossroads in immune signaling

Persistent infections with a high-risk type human papillomavirus (hrHPV) can progress to cancer. High-risk HPVs infect keratinocytes (KCs) and successfully suppress host immunity for up to two years despite the fact that KCs are well equipped to detect and initiate immune responses to invading pathogens. Viral persistence is achieved by active interference with KCs innate and adaptive immune mechanisms. To this end hrHPV utilizes proteins encoded by its viral genome, as well as exploits cellular proteins to interfere with signaling of innate and adaptive immune pathways. This results in impairment of interferon and pro-inflammatory cytokine production and subsequent immune cell attraction, as well as resistance to incoming signals from the immune system. Furthermore, hrHPV avoids the killing of infected cells by interfering with antigen presentation to antigen-specific cytotoxic T lymphocytes. Thus, hrHPV has evolved multiple mechanisms to avoid detection and clearance by both the innate and adaptive immune system, the molecular mechanisms of which will be dealt with in detail in this review.

Ubiquitin carboxyl-terminal esterase L1 promotes proliferation of human choroidal and retinal endothelial cells

PURPOSE

We aimed: (1) to establish endothelial expression of ubiquitin carboxyl-terminal esterase L1 (UCHL1) in human choroid and retina and; (2) to investigate a role for UCHL1 in basic processes involved in intraocular neovascularization.

DESIGN

Controlled translational experimental study.

METHODS

Ethanol-fixed human choroid and retina (n = 3 eyes) were indirectly immunostained with rabbit anti-human UCHL1 antibody. Endothelial proliferation and migration assays were performed using cultured human choroidal and retinal endothelial cells (n = 6 isolates/assay). Cells were transfected with UCHL1-targeted or non-targeted small interfering (si)RNA and a commercially available transfection system, and used 48 hours later in experiments. Cell proliferation was evaluated using an assay in which cellular DNA was fluorescently tagged for quantification by microplate reader. Cell migration was examined in an assay that involved counting the number of endothelial cells moving across a perforated membrane. Transcript silencing was verified by Western blot for all assays.

RESULTS

Immunohistochemistry confirmed expression of UCHL1 by endothelium in human choroid and retina in vivo. UCHL1-specific knockdown resulted in significantly less proliferation (p < 0.0001) for 3 human choroidal endothelial isolates and 3 human retinal endothelial isolates, and significantly less migration (p ≤ 0.016) for 2 of 3 human choroidal endothelial isolates and 1 of 3 human retinal endothelial isolates.

CONCLUSIONS

Our results suggest that UCHL1 may be involved in choroidal and retinal endothelial proliferation in most persons, and endothelial migration in some persons. UCHL1 may be a suitable target for a new treatment of intraocular neovascularisation.

CD40-mediated amplification of local immunity by epithelial cells is impaired by HPV

The interaction between the transmembrane glycoprotein surface receptor CD40 expressed by skin epithelial cells (ECs) and its T-cell–expressed ligand CD154 was suggested to exacerbate inflammatory skin diseases. However, the full spectrum of CD40-mediated effects by ECs underlying this observation is unknown. Therefore, changes in gene expression after CD40 ligation of ECs were studied by microarrays. CD40-mediated activation for 2 hours stimulated the expression of a coordinated network of immune-involved genes strongly interconnected by IL8 and TNF, whereas after 24 hours anti-proliferative and anti-apoptotic genes were upregulated. CD40 ligation was associated with the production of chemokines and the attraction of lymphocytes and myeloid cells from peripheral blood mononuclear cells (PBMCs). Thus, CD40-mediated activation of ECs resulted in a highly coordinated response of genes required for the local development and sustainment of adaptive immune responses. The importance of this process was confirmed by a study on the effects of human papilloma virus (HPV) infection to the EC's response to CD40 ligation. HPV infection clearly attenuated the magnitude of the response to CD40 ligation and the EC's capacity to attract PBMCs. The fact that HPV attenuates CD40 signaling in ECs indicates the importance of the CD40-CD154 immune pathway in boosting cellular immunity within epithelia.

The proteomic response in glioblastoma in young patients

Increasing age is an important prognostic variable in glioblastoma (GBM). We have defined the proteomic response in GBM samples from 7 young patients (mean age 36 years) compared to peritumoural-control samples from 10 young patients (mean age 32 years). 2-Dimensional-gel-electrophoresis, image analysis, and protein identification (LC/MS) were performed. 68 proteins were significantly altered in young GBM samples with 29 proteins upregulated and 39 proteins downregulated. Over 50 proteins are described as altered in GBM for the first time. In a parallel analysis in old GBM (mean age 67 years), an excellent correlation could be demonstrated between the proteomic profile in young GBM and that in old GBM patients (r² = 0.95) with only 5 proteins altered significantly (p < 0.01). The proteomic response in young GBM patients highlighted alterations in protein–protein interactions in the immunoproteosome, NFkB signalling, and mitochondrial function and the same systems participated in the responses in old GBM patients.

Ubiquitin carboxyl terminal hydrolyase L1-suppressed autophagic degradation of p21WAF1/Cip1 as a novel feedback mechanism in the control of cardiac fibroblast proliferation

Aims

Deubiquitinating enzymes (DUBs) appear to be critical regulators of a multitude of processes such as proliferation, apoptosis, differentiation, and inflammation; however, the potential roles of DUBs in the heart remain to be determined. This study was aimed to explore the role of a DUB, ubiquitin carboxyl terminal hydrolyase L1 (UCH-L1) in maladaptive cardiac remodeling and dysfunction.

Methods and Results

Maladaptive cardiac remodeling and dysfunction were induced in mice by transverse aortic constriction (TAC). UCH-L1 expression was transiently increased and then declined near to the basal level while impairment of cardiac function proceeded. The upregulation of UCH-L1 was observed in cardiac myocytes and fibroblasts. In primary culture of cardiac fibroblasts, UCH-L1 was upregulated by platelet-derived growth factor (PDGF)-BB and PDGF-DD. Adenoviral overexpession of UCH-L1 inhibited the PDGF-induced cardiac fibroblast proliferation without affecting the activation of mitogen activated protein kinases (MAPKs), Akt, and signal transducers and activators of transcription 3 (STAT3). Further signaling dissection revealed that PDGF-BB posttranscriptional upregulated p21^WAF1/Cip1 protein expression, which was inhibited by rapamycin, an activator of autophagy via suppressing mammalian target of rapamycin (mTOR), rather than MG132, a proteasome inhibitor. Overexpression of UCH-L1 enhanced PDGF-BB-induced mTOR phosphorylation and upregulation of p21^WAF1/Cip1 protein expression while suppressed autophagic flux in cardiac fibroblasts.

Conclusion

UCH-L1 facilitates PDGF-BB-induced suppression of autophagic degradation of p21^WAF1/Cip1 proteins in cardiac fibroblasts, which may serve as a novel negative feedback mechanism in the control of cardiac fibroblast proliferation contributing to cardiac fibrosis and dysfunction.

SUMO and Parkinson's disease

Parkinson's disease (PD) is one of the most common degenerative disorders of the central nervous system that produces motor and non-motor symptoms. The majority of cases are idiopathic and characterized by the presence of Lewy bodies containing fibrillar α-synuclein. Small ubiquitin-related modifier (SUMO) immunoreactivity was observed among others in cases with PD. Key disease-associated proteins are SUMO-modified, linking this posttranslational modification to neurodegeneration. SUMOylation and SUMO-mediated mechanisms have been intensively studied in recent years, revealing nuclear and extranuclear functions for SUMO in a variety of cellular processes, including the regulation of transcriptional activity, modulation of signal transduction pathways, and response to cellular stress. This points to a role for SUMO more than just an antagonist to ubiquitin and proteasomal degradation. The identification of risk and age-at-onset gene loci was a breakthrough in PD and promoted the understanding of molecular mechanisms in the pathology. PD has been increasingly linked with mitochondrial dysfunction and impaired mitochondrial quality control. Interestingly, SUMO is involved in many of these processes and up-regulated in response to cellular stress, further emphasizing the importance of SUMOylation in physiology and disease.

Altered ubiquitin-proteasome signaling in right ventricular hypertrophy and failure

Alterations in the ubiquitin-proteasome system (UPS) have been described in left ventricular hypertrophy and failure, although results have been inconsistent. The role of the UPS in right ventricular (RV) hypertrophy (RVH) and RV failure (RVF) is unknown. Given the greater percent increase in RV mass associated with RV afterload stress, as present in many congenital heart lesions, we hypothesized that alterations in the UPS could play an important role in RVH/RVF. UPS expression and activity were measured in the RV from mice with RVH/RVF secondary to pulmonary artery constriction (PAC). Epoxomicin and MG132 were used to inhibit the proteasome, and overexpression of the 11S PA28α subunit was used to activate the proteasome. PAC mice developed RVH (109.3% increase in RV weight to body weight), RV dilation with septal shift, RV dysfunction, and clinical RVF. Proteasomal function (26S β₅ chymotrypsin-like activity) was decreased 26% (P < 0.05). Protein expression of 19S subunit Rpt5 (P < 0.05), UCHL1 deubiquitinase (P < 0.0001), and Smurf1 E3 ubiquitin ligase (P < 0.01) were increased, as were polyubiquitinated proteins (P < 0.05) and free-ubiquitins (P = 0.05). Pro-apoptotic Bax was increased (P < 0.0001), whereas anti-apoptotic Bcl-2 decreased (P < 0.05), resulting in a sixfold increase in the Bax/Bcl-2 ratio. Proteasomal inhibition did not accelerate RVF. However, proteasome enhancement by cardiac-specific proteasome overexpression partially improved survival. Proteasome activity is decreased in RVH/RVF, associated with upregulation of key UPS regulators and pro-apoptotic signaling. Enhancement of proteasome function partially attenuates RVF, suggesting that UPS dysfunction contributes to RVF.

Human papillomavirus (HPV) upregulates the cellular deubiquitinase UCHL1 to suppress the keratinocyte's innate immune response

Persistent infection of basal keratinocytes with high-risk human papillomavirus (hrHPV) may cause cancer. Keratinocytes are equipped with different pattern recognition receptors (PRRs) but hrHPV has developed ways to dampen their signals resulting in minimal inflammation and evasion of host immunity for sustained periods of time. To understand the mechanisms underlying hrHPV's capacity to evade immunity, we studied PRR signaling in non, newly, and persistently hrHPV-infected keratinocytes. We found that active infection with hrHPV hampered the relay of signals downstream of the PRRs to the nucleus, thereby affecting the production of type-I interferon and pro-inflammatory cytokines and chemokines. This suppression was shown to depend on hrHPV-induced expression of the cellular protein ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) in keratinocytes. UCHL1 accomplished this by inhibiting tumor necrosis factor receptor-associated factor 3 (TRAF3) K63 poly-ubiquitination which lead to lower levels of TRAF3 bound to TANK-binding kinase 1 and a reduced phosphorylation of interferon regulatory factor 3. Furthermore, UCHL1 mediated the degradation of the NF-kappa-B essential modulator with as result the suppression of p65 phosphorylation and canonical NF-κB signaling. We conclude that hrHPV exploits the cellular protein UCHL1 to evade host innate immunity by suppressing PRR-induced keratinocyte-mediated production of interferons, cytokines and chemokines, which normally results in the attraction and activation of an adaptive immune response. This identifies UCHL1 as a negative regulator of PRR-induced immune responses and consequently its virus-increased expression as a strategy for hrHPV to persist.

Circulating brain microvascular endothelial cells (cBMECs) as potential biomarkers of the blood-brain barrier disorders caused by microbial and non-microbial factors

Despite aggressive research, central nervous system (CNS) disorders, including blood-brain barrier (BBB) injury caused by microbial infection, stroke, abused drugs [e.g., methamphetamine (METH) and nicotine], and other pathogenic insults, remain the world's leading cause of disabilities. In our previous work, we found that dysfunction of brain microvascular endothelial cells (BMECs), which are a major component of the BBB, could be caused by nicotine, meningitic pathogens and microbial factors, including HIV-1 virulence factors gp41 and gp120. One of the most challenging issues in this area is that there are no available cell-based biomarkers in peripheral blood for BBB disorders caused by microbial and non-microbial insults. To identify such cellular biomarkers for BBB injuries, our studies have shown that mice treated with nicotine, METH and gp120 resulted in increased blood levels of CD146+(endothelial marker)/S100B+ (brain marker) circulating BMECs (cBMECs) and CD133+[progenitor cell (PC) marker]/CD146+ endothelial PCs (EPCs), along with enhanced Evans blue and albumin extravasation into the brain. Nicotine and gp120 were able to significantly increase the serum levels of ubiquitin C-terminal hydrolase 1 (UCHL1) (a new BBB marker) as well as S100B in mice, which are correlated with the changes in cBMECs and EPCs. Nicotine- and meningitic E. coli K1-induced enhancement of cBMEC levels, leukocyte migration across the BBB and albumin extravasation into the brain were significantly reduced in alpha7 nAChR knockout mice, suggesting that this inflammatory regulator plays an important role in CNS inflammation and BBB disorders caused by microbial and non-microbial factors. These results demonstrated that cBMECs as well as EPCs may be used as potential cell-based biomarkers for indexing of BBB injury.

Emerging molecular targets for brain repair after stroke

The field of neuroprotection generated consistent preclinical findings of mechanisms of cell death but these failed to be translated into clinics. The approaches that combine the modulation of the inhibitory environment together with the promotion of intrinsic axonal outgrowth needs further work before combined therapeutic strategies will be transferable to clinic trials. It is likely that only when some answers have been found to these issues will our therapeutic efforts meet our expectations. Stroke is a clinically heterogeneous disease and combinatorial treatments require much greater work in pharmacological and toxicological testing. Advances in genetics and results of the Whole Human Genome Project (HGP) provided new unknown information in relation to stroke. Genetic factors are not the only determinants of responses to some diseases. It was recognized early on that "epigenetic" factors were major players in the aetiology and progression of many diseases like stroke. The major players are microRNAs that represent the best-characterized subclass of noncoding RNAs. Epigenetic mechanisms convert environmental conditions and physiological stresses into long-term changes in gene expression and translation. Epigenetics in stroke are in their infancy but offer great promise for better understanding of stroke pathology and the potential viability of new strategies for its treatment.

Proteomic analysis revealed nitrogen-mediated metabolic, developmental, and hormonal regulation of maize (Zea mays L.) ear growth

Optimal nitrogen (N) supply is critical for achieving high grain yield of maize. It is well established that N deficiency significantly reduces grain yield and N oversupply reduces N use efficiency without significant yield increase. However, the underlying proteomic mechanism remains poorly understood. The present field study showed that N deficiency significantly reduced ear size and dry matter accumulation in the cob and grain, directly resulting in a significant decrease in grain yield. The N content, biomass accumulation, and proteomic variations were further analysed in young ears at the silking stage under different N regimes. N deficiency significantly reduced N content and biomass accumulation in young ears of maize plants. Proteomic analysis identified 47 proteins with significant differential accumulation in young ears under different N treatments. Eighteen proteins also responded to other abiotic and biotic stresses, suggesting that N nutritional imbalance triggered a general stress response. Importantly, 24 proteins are involved in regulation of hormonal metabolism and functions, ear development, and C/N metabolism in young ears, indicating profound impacts of N nutrition on ear growth and grain yield at the proteomic level.

Mammalian target of rapamycin complex 2 regulates inflammatory response to stress

OBJECTIVE AND DESIGN

To explore the role of mammalian target of rapamycin 2 (mTORC2) in the activation of inflammatory and oxidative responses in rodent models of acute injury and metabolic stress.

MATERIAL

The impact of nephrilin, an inhibitor of mTORC2 complex, was assessed in three CD-1 mouse models of acute xenobiotic stress and in a hypertensive Dahl rat model of metabolic stress.

METHODS

Animals received daily subcutaneous bolus injections of saline or 4 mg/kg nephrilin. Tissues were assayed by ELISA, gene arrays and immunohistochemical staining.

RESULTS

Nephrilin significantly inhibited elevations in plasma tumor necrosis factor-alpha, kidney substance P, and CX3CR1, and urinary lipocalin-2 [urinary neutrophil gelatinase-associated lipocalin (uNGAL)] in models of acute xenobiotic stress. UCHL1 gene expression levels dropped and plasma HMGB1 levels rose in the rhabdomyolysis model. Both effects were reversed by nephrilin. The inhibitor also blocked diet-induced elevations of uNGAL and albumin-creatinine ratio (UACR) as well as kidney tissue phosphorylation of PKC-beta-2-T641 and p66shc-S36, and reduced dark ring-like staining of nuclei by anti-phos-p66shc-S36 antibody in frozen sections of diseased kidneys from hypertensive Dahl rats fed an 8 % NaCl diet for 4 weeks.

CONCLUSIONS

Taken together, our results suggest a role for mTORC2 in the inflammatory-oxidative responses to stress.

Attenuation of early atherogenesis in low-density lipoprotein receptor-deficient mice by proteasome inhibition

OBJECTIVE

Low and nontoxic proteasome inhibition has anti-inflammatory, antiproliferative, and antioxidative effects on vascular cells in vitro and in vivo. We hypothesized that low-dose inhibition of the proteasome could provide antiatherogenic protection. The present study investigated the effect of low-dose proteasome inhibition on early lesion formation in low-density lipoprotein receptor-deficient mice fed a Western-type diet.

METHODS AND RESULTS

Male low-density lipoprotein receptor-deficient mice, 10 weeks old, were fed a Western-type diet for 6 weeks with intraperitoneal injections of bortezomib or solvent. Bortezomib was injected at a dose of 50 μg/kg body weight. Cholesterol plasma levels were not affected by bortezomib treatment. En face Oil Red O staining of aortae and aortic root cryosections demonstrated significant reduction of atherosclerotic lesion coverage in bortezomib-treated animals. Bortezomib significantly reduced vascular cellular adhesion molecule-1 expression and macrophage infiltration as shown by histological analysis. Bortezomib treatment resulted in a significant reduction of superoxide content, lipid peroxidation and protein oxidation products, serum levels of monocyte chemoattractant protein-1, and interleukin-6. Gene expression microarray analysis showed that expressional changes induced by Western-type diet were attenuated by treatment with low-dose bortezomib.

CONCLUSIONS

Low-dose proteasome inhibition exerts antioxidative and anti-inflammatory effects and attenuates development of atherosclerotic lesions in low-density lipoprotein receptor-deficient mice.

A pro-inflammatory role of deubiquitinating enzyme cylindromatosis (CYLD) in vascular smooth muscle cells

CYLD, a deubiquitinating enzyme (DUB), is a critical regulator of diverse cellular processes, ranging from proliferation and differentiation to inflammatory responses, via regulating multiple key signaling cascades such as nuclear factor kappa B (NF-κB) pathway. CYLD has been shown to inhibit vascular lesion formation presumably through suppressing NF-κB activity in vascular cells. However, herein we report a novel role of CYLD in mediating pro-inflammatory responses in vascular smooth muscle cells (VSMCs) via a mechanism independent of NF-κB activity. Adenoviral knockdown of Cyld inhibited basal and the tumor necrosis factor alpha (TNFα)-induced mRNA expression of pro-inflammatory cytokines including monocyte chemotactic protein-1 (Mcp-1), intercellular adhesion molecule (Icam-1) and interleukin-6 (Il-6) in rat adult aortic SMCs (RASMCs). The CYLD deficiency led to increases in the basal NF-κB transcriptional activity in RASMCs; however, did not affect the TNFα-induced NF-κB activity. Intriguingly, the TNFα-induced IκB phosphorylation was enhanced in the CYLD deficient RASMCs. While knocking down of Cyld decreased slightly the basal expression levels of IκBα and IκBβ proteins, it did not alter the kinetics of TNFα-induced IκB protein degradation in RASMCs. These results indicate that CYLD suppresses the basal NF-κB activity and TNFα-induced IκB kinase activation without affecting TNFα-induced NF-κB activity in VSMCs. In addition, knocking down of Cyld suppressed TNFα-induced activation of mitogen activated protein kinases (MAPKs) including extracellular signal-activated kinases (ERK), c-Jun N-terminal kinase (JNK), and p38 in RASMCs. TNFα-induced RASMC migration and monocyte adhesion to RASMCs were inhibited by the Cyld knockdown. Finally, immunochemical staining revealed a dramatic augment of CYLD expression in the injured coronary artery with neointimal hyperplasia. Taken together, our results uncover an unexpected role of CYLD in promoting inflammatory responses in VSMCs via a mechanism involving MAPK activation but independent of NF-κB activity, contributing to the pathogenesis of vascular disease.

Control of BACE1 degradation and APP processing by ubiquitin carboxyl-terminal hydrolase L1

Deposition of amyloid β protein (Aβ) in the brain is the hallmark of Alzheimer's disease (AD) pathogenesis. Beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the β-secretase in vivo essential for generation of Aβ. Previously we demonstrated that BACE1 is ubiquitinated and the degradation of BACE1 is mediated by the ubiquitin-proteasome pathway (UPP). However the mechanism underlying regulation of BACE1 degradation by UPP remains elusive. Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme highly specific to neuron, catalyzing the hydrolysis of ubiquitin conjugates from ubiquitinated substrates. UCHL1 regulates ubiquitin-dependent protein degradation. However, whether UCHL1 is particularly involved in the proteasomal degradation of BACE1 and what is the role of UCHL1 in AD pathogenesis remain elusive. To investigate the effect of UCHL1 on BACE1 degradation, HUCH cells, a UCHL1 stably over-expressed HEK293 cell line, was established. We found that inhibition of UCHL1 significantly increased BACE1 protein level in a time-dependent manner. Half life of BACE1 was reduced in HUCH cells compared with HEK. Over-expression of UCHL1 decreased APP C-terminal fragment C99 and Aβ levels in HUCH cells. Moreover, disruption of Uchl1 gene significantly elevated levels of endogenous BACE1, C99 and Aβ in the Uchl1-null gad mice. These results demonstrated that UCHL1 accelerates BACE1 degradation and affects APP processing and Aβ production. This study suggests that potentiation of UCHL1 might be able to reduce the level of BACE1 and Aβ in brain, which makes it a novel target for AD drug development.

The ubiquitin-proteasome system and cardiovascular disease

Over the past decade, the role of the ubiquitin-proteasome system (UPS) has been the subject of numerous studies to elucidate its role in cardiovascular physiology and pathophysiology. There have been many advances in this field including the use of proteomics to achieve a better understanding of how the cardiac proteasome is regulated. Moreover, improved methods for the assessment of UPS function and the development of genetic models to study the role of the UPS have led to the realization that often the function of this system deviates from the norm in many cardiovascular pathologies. Hence, dysfunction has been described in atherosclerosis, familial cardiac proteinopathies, idiopathic dilated cardiomyopathies, and myocardial ischemia. This has led to numerous studies of the ubiquitin protein (E3) ligases and their roles in cardiac physiology and pathophysiology. This has also led to the controversial proposition of treating atherosclerosis, cardiac hypertrophy, and myocardial ischemia with proteasome inhibitors. Furthering our knowledge of this system may help in the development of new UPS-based therapeutic modalities for mitigation of cardiovascular disease.