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The aim of the present study was to investigate whether resveratrol could reduce nigral iron levels to prevent the degeneration of dopaminergic neurons in the substantia nigra (SN) of C57BL/6 mice induced by rotenone. Parkinson’s disease (PD) is an age-related neurodegenerative disorder; elevated iron levels in the SN participate in neuronal death in PD. Resveratrol is a kind of polyphenolic compounds and possess antioxidant, anticancer, and anti-inflammatory biological functions. Although many research groups have investigated the neuroprotective effects of resveratrol against PD, the precise mechanisms underlying its beneficial effects on dopaminergic neuron are poorly defined. In this study, rotenone-treated mice were used to examine neuroprotective roles of resveratrol in PD. Sixty-four adult C57BL/6 mice were divided into four groups: vehicle control mice, rotenone mice, resveratrol-treated rotenone mice, resveratrol mice. In the present study, we found that chronic administration of rotenone significantly induced motor coordination impairment and increased iron levels and dopaminergic neuron loss in SN in mice. Resveratrol administration significantly protected mice from rotenone-induced motor coordination impairment, elevated iron levels, and dopaminergic neuronal loss. Our results show that resveratrol can elicit neuroprotective effects on rotenone-induced parkinsonism through reducing nigral iron levels.

The present study aimed to evaluate alterations in the levels of iron, divalent metal transporter 1 (DMT1) with the iron-responsive element (IRE), transferrin receptor 1 (TfR1), ferroportin 1 (FPN1), and iron regulatory protein 1 (IRP1) in the temporal cortex of human brains with Parkinson disease (PD).

Background: We recently reported elevated cerebrospinal fluid (CSF) levels of soluble tumor necrosis factor (TNF) receptors and TNF- converting enzyme (TACE) activity in subjects with Alzheimers disease (AD) in a Caucasian population. The TNF receptor-mediated signaling pathway contributes to the production of A and the subsequent cytotoxicity that is observed in AD brains. However, whether the plasma levels of soluble TNF receptors (sTNFRs) are changed is still unclear in AD patients of Han descent. Methods: In the present study, we analyzed the plasma sTNFR levels using commercially available immunoassay kits in 76 AD patients and 40 age- and sex-matched control subjects of Northern Han Chinese descent. Furthermore, the TACE activity was measured using a solution-based assay containing a fluorescently labeled TACE substrate. Results: AD patients exhibited higher levels of both sTNFR and TACE activity in their plasma compared with age- and sex-matched control subjects. The levels of sTNFR1 strongly correlated with the levels of sTNFR2 (rs =0.526, P<0.001). In addition, the levels of sTNFR1 were significantly correlated with TACE activity (rs = 0.308, P<0.01). Conclusion: These results suggest that sTNFRs and TACE activity might serve as potential peripheral diagnostic candidate biomarkers in AD.

The regulatory (R) domain of the cystic fibrosis transmembrane conductance regulator (CFTR) contains consensus phosphorylation sites for cAMP-dependent protein kinase (PKA) that are the basis for physiological regulation of the CFTR chloride channel. A short peptide segment in the R domain with a net negative charge of B9 (amino acids 817–838, NEG2) and predicted helical tendency is shown to play a critical role in CFTR chloride channel function. Deletion of NEG2 from CFTR completely eliminates the PKA dependence of channel activity. Exogenous NEG2 peptide interacts with CFTR to exert both stimulatory and inhibitory effects on the channel function. The NEG2 peptide with sequence scrambled to remove helical tendencies also inhibits channel function, but does not stimulate. Similar results are found for a NEG2 peptide whose helical structure is disrupted by a proline residue. When six of the negatively charged carboxylic acid residues are replaced by their cognate amides, reducing net negative charge to B3, but increasing helical propensity as assessed by circular dichroism, the peptide stimulates CFTR channel function, but does not inhibit. We speculate that the NEG2 region interacts with other cytosolic domains of CFTR to control opening and closing transitions of the chloride channel.

The R domain of cystic fibrosis transmembrane conductance regulator (CFTR), when phosphorylated, undergoes conformational change, and the chloride channel opens. We investigated the contribution of R domain conformation, apart from the changes induced by phosphorylation, to channel opening, by testing the effect of the peptidyl-prolyl isomerase, cyclophilin A, on the CFTR channel. When it was applied after the channel had been opened by PKA phosphorylation, cyclophilin A increased the open probability of wild-type CFTR (from Po=0.197±0.010 to Po=0.436±0.029) by increasing the number of channel openings, not open time. Three highly conserved proline residues in the R domain, at positions 740, 750, and 759, were considered as candidate targets for cyclophilin A. Mutations of these prolines to alanines (P3A mutant) resulted in a channel unresponsive to cyclophilin A but with pore properties similar to the wild type, under strict control of PKA and ATP, but with significantly increased open probability (Po=0.577±0.090) compared to wild-type CFTR, again due to an increase in the number of channel openings and not open time. Mutation of each of the proline residues separately and in pairs demonstrated that all three proline mutations are required for maximal Po. When P3A was expressed in 293 HEK cells and tested by SPQ assay, chloride efflux was significantly increased compared to cells transfected with wild-type CFTR. Thus, treatments favoring the trans-peptidyl conformation about conserved proline residues in the R domain of CFTR affect openings of CFTR, above and beyond the effect of PKA phosphorylation.

The cystic fibrosis transmembrane conductance regulator (CFTR) constitutes a linear conductance chloride channel, which is regulated by cAMP-dependent protein kinase phosphorylation at multiple sites located in the intracellular regulatory (R) domain. Studies in a lipid bilayer system, reported here, provide evidence for the control of CFTR chloride channel by its R domain. The exogenous R domain protein (encoded by exon 13 plus 85 base pairs of exon 14) interacted specifically with the CFTR molecule and inhibited the chloride conductance in a phosphorylation-dependent manner. Only the unphosphorylated R domain protein blocked the CFTR channel. Such functional interaction suggests that the putative gating particle of the CFTR chloride channel resides in the R domain.

For a cystic fibrosis transmembrane conductance regulator (CFTR) channel to enter its open state, serine residues in the R domain must be phosphorylated by cAMP-dependent protein kinase, and intracellular ATP must bind to the nucleotide-binding folds and subsequently be hydrolyzed. CFTR with its R domain partially removed, ΔR(708–835)-CFTR, forms a chloride channel that opens independently of protein kinase A phosphorylation, with open probability approximately one-third that of the wild type CFTR channel. Deletion of this portion of the R domain from CFTR alters the response of the channel to 5′-adenylylimidodiphosphate, pyrophosphate, and vanadate, compounds that prolong burst duration of the wild type CFTR channel but fail to do so in the ΔR-CFTR. In addition, the addition of exogenous unphosphorylated R domain protein, which blocks the wild type CFTR channel, has no effect on the ΔR-CFTR channel. However, when the exogenous R domain is phosphorylated, significant stimulation of the ΔR-CFTR channel results;Poincreases from 0.10 to 0.22. These data are consistent with a model for CFTR function in which the R domain in the unphosphorylated state interacts with the first nucleotide binding fold to inhibit either binding or hydrolysis of ATP or transduction of the effect to open the pore, but when the R domain is phosphorylated, it undergoes conformational change and interacts at a separate site in the first nucleotide binding fold to stimulate either binding or hydrolysis of ATP or transduction of the effect to open the pore.