TRAP1: A Metabolic Hub Linking Aging Pathophysiology to Mitochondrial S-Nitrosylation

Nitrosative stress in Parkinson's disease

Parkinson’s Disease (PD) is a neurodegenerative disorder characterized, in part, by the loss of dopaminergic neurons within the nigral-striatal pathway. Multiple lines of evidence support a role for reactive nitrogen species (RNS) in degeneration of this pathway, specifically nitric oxide (NO). This review will focus on how RNS leads to loss of dopaminergic neurons in PD and whether RNS accumulation represents a central signal in the degenerative cascade. Herein, we provide an overview of how RNS accumulates in PD by considering the various cellular sources of RNS including nNOS, iNOS, nitrate, and nitrite reduction and describe evidence that these sources are upregulating RNS in PD. We document that over 1/3 of the proteins that deposit in Lewy Bodies, are post-translationally modified (S-nitrosylated) by RNS and provide a broad description of how this elicits deleterious effects in neurons. In doing so, we identify specific proteins that are modified by RNS in neurons which are implicated in PD pathogenesis, with an emphasis on exacerbation of synucleinopathy. How nitration of alpha-synuclein (aSyn) leads to aSyn misfolding and toxicity in PD models is outlined. Furthermore, we delineate how RNS modulates known PD-related phenotypes including axo-dendritic-, mitochondrial-, and dopamine-dysfunctions. Finally, we discuss successful outcomes of therapeutics that target S-nitrosylation of proteins in Parkinson’s Disease related clinical trials. In conclusion, we argue that targeting RNS may be of therapeutic benefit for people in early clinical stages of PD.

TRAP1 in Oxidative Stress and Neurodegeneration

Tumor necrosis factor receptor-associated protein 1 (TRAP1), also known as heat shock protein 75 (HSP75), is a member of the heat shock protein 90 (HSP90) chaperone family that resides mainly in the mitochondria. As a mitochondrial molecular chaperone, TRAP1 supports protein folding and contributes to the maintenance of mitochondrial integrity even under cellular stress. TRAP1 is a cellular regulator of mitochondrial bioenergetics, redox homeostasis, oxidative stress-induced cell death, apoptosis, and unfolded protein response (UPR) in the endoplasmic reticulum (ER). TRAP1 has attracted increasing interest as a therapeutical target, with a special focus on the design of TRAP1 specific inhibitors. Although TRAP1 was extensively studied in the oncology field, its role in central nervous system cells, under physiological and pathological conditions, remains largely unknown. In this review, we will start by summarizing the biology of TRAP1, including its structure and related pathways. Thereafter, we will continue by debating the role of TRAP1 in the maintenance of redox homeostasis and protection against oxidative stress and apoptosis. The role of TRAP1 in neurodegenerative disorders will also be discussed. Finally, we will review the potential of TRAP1 inhibitors as neuroprotective drugs.

TRAP1 Shows Clinical Significance in the Early Diagnosis of Small Cell Lung Cancer

Purpose

To explore the clinical significance of tumor necrosis factor receptor-associated protein (TRAP1), mitotic arrest deficient 2 (mad2) and anti-nuclear mitotic spindle apparatus antibody (MSA) in the diagnosis of small cell lung cancer (SCLC).

Patients and Methods

Serum concentrations of TRAP1 and MSA were determined by enzyme-linked immunosorbent assay (ELISA), including SCLC group (Num.=86), non-small cell lung cancer (NSCLC) group (Num.=105), pulmonary nodules (PN) group (Num.=94), and 60 healthy subjects as control group (Num.=60). Whereas fluorescence quantitative PCR (qt-PCR) method was used to detect the expression of mad2.

Results

The expression of TRAP1 was low in SCLC and NSCLC compared with the other two groups, and was the lowest in SCLC, which was negatively correlated with the occurrence of the disease (P<0.05); the sensitivity and specificity of TRAP1 for SCLC were 75.29%, 93.33%, and the area under SCLC curve was 0.903; compared with the other three groups, the level of MSA was the highest in the SCLC, and the results were significantly different (P<0.05), while the area under the SCLC curve was 0.856, and the sensitivity and specificity were 62.78% and 95.24%, respectively. Mad2 is overexpressed in SCLC, but not in PN. The area under the SCLC curve is 0.835, and the sensitivity and specificity are 56.98% and 92.38%; TRAP1 levels are negatively correlated with SCLC tumor stage, the level of TRAP1 was significantly lower in stage III–IV than in stage I–II (P<0.05); combined analysis of TRAP1 and MAD2 and MSA showed that the sensitivity and specificity for SCLS were 95.35% and 99.05%, respectively.

Conclusion

TRAP1 is of great value in the early diagnosis of SCLC as well as differential diagnosis with NSCLC. TRAP1 combined with MAD2 and MSA improved the sensitivity and specificity and provided a new idea for the clinical diagnosis of SCLC.

Exploiting S-nitrosylation for cancer therapy: facts and perspectives

S-nitrosylation, the post-translational modification of cysteines by nitric oxide, has been implicated in several cellular processes and tissue homeostasis. As a result, alterations in the mechanisms controlling the levels of S-nitrosylated proteins have been found in pathological states. In the last few years, a role in cancer has been proposed, supported by the evidence that various oncoproteins undergo gain- or loss-of-function modifications upon S-nitrosylation. Here, we aim at providing insight into the current knowledge about the role of S-nitrosylation in different aspects of cancer biology and report the main anticancer strategies based on: (i) reducing S-nitrosylation-mediated oncogenic effects, (ii) boosting S-nitrosylation to stimulate cell death, (iii) exploiting S-nitrosylation through synthetic lethality.