Fadime Aydin Kose

Different p97/VCP complexes function in retrotranslocation step of mammalian Er-associated degradation (ERAD)

Studies in yeast indicate that three specialized endoplasmic reticulum-associated degradation (ERAD) pathways, namely ERAD-L, -M, or -C, dispose substrates with structural lesions in the lumenal, transmembrane, or cytosolic domains, respectively. The ubiquitin ligase (E3) Hrd1p and its cooperating partners are required for ERAD-L and -M pathways, whereas Doa10p complex is required for the ERAD-C pathway. We investigated these pathways in mammalian cells by assessing the requirements of the mammalian ERAD E3s, gp78 and Hrd1, in degradation of four substrates each with different type of structural lesions: CD3δ, Z-variant α1-antitrypsin, tyrosinase (C89R) and mutant cystic fibrosis transmembrane conductance regulator (CFTRΔF508). We demonstrated that tyrosinase (C89R) is a substrate for Hrd1 while all others are gp78 substrates. Knockdown of Hrd1 diminished gp78 substrate levels, but silencing of gp78 had no effect on Hrd1s substrate, suggesting that the functional interaction between Hrd1 and gp78 is unidirectional. Furthermore, while Ufd1 is dispensable for gp78-mediated ERAD, it is essential for Hrd1-mediated ERAD. Interestingly, Npl4 was found to be a key component for both pathways. These results suggest that the Hrd1-mediated ERAD requires a well-established retrotranslocation machinery, the p97/VCP-Ufd1-Npl4 complex, whereas the gp78 pathway needs only p97/VCP and Npl4. In addition, the three distinct ERAD pathways described in yeast may not be strictly conserved in mammalian cells as gp78 can function on three substrates with different structural lesions.

A unique IBMPFD-related P97/VCP mutation with differential binding pattern and subcellular localization.

p97/VCP is a hexameric AAA type ATPase that functions in a variety of cellular processes such as endoplasmic reticulum associated degradation (ERAD), organelle biogenesis, autophagy and cell-cycle regulation. Inclusion body myopathy associated with Paget disease of the bone and frontotemporal dementia (IBMPFD) is an autosomal dominant disorder which has been attributed to mutations in p97/VCP. Several missense mutations affecting twelve different amino acids have been identified in IBMPFD patients and some of them were suggested to be involved in the observed pathology. Here, we analyzed the effect of all twelve p97/VCP variants on ERAD substrates and their cofactor binding abilities. While all mutants cause ERAD substrate accumulation, P137L mutant p97/VCP differs from other IBMPFD mutants by having a unique solubility profile and subcellular localization. Intriguingly, although almost all mutants exhibit enhanced p47 and Ufd1-Npl4 binding, the P137L mutation completely abolishes p97/VCP interactions with Ufd1, Npl4 and p47, while retaining its gp78 binding. While recombinant R155C mutant protein consistently interacts with both Ufd1 and VIM of gp78, P137L mutant protein lost binding ability to Ufd1 but not to VIM in vitro. The differential impairments in p97/VCP interactions with its functional partners and function should help our understanding of the molecular pathogenesis of IBMPFD.

Oxidative and Nitrosative Stress Markers in Patients on Hemodialysis and Peritoneal Dialysis

Aim: The aim of this study was to evaluate the effects of hemodialysis (HD) and peritoneal dialysis (PD) treatments on oxidative and nitrosative stress markers comparatively. Methods: Twenty HD and 20 PD patients as well as 20 healthy individuals were included in this study. Plasma advanced oxidation protein products, myeloperoxidase, thiol group and 3-nitrotyrosine (3-NT) levels were measured in all subjects. Results: Plasma advanced oxidation protein products and myeloperoxidase levels were elevated by HD and PD treatments when compared to the control group. Conversely, plasma thiol group levels were decreased in HD and PD patients. 3-NT levels were increased by HD treatment only. Conclusions: The elevated plasma 3-NT levels in pre-HD and post-HD patients suggest that those patients have a considerably increased risk for nitrosative tissue injury. However, similar 3-NT levels of the control and PD groups support the advantage of PD therapy in terms of nitrosative tissue injury.

Antioxidant properties evaluation of topical astaxanthin formulations as anti-aging products

The reactive oxygen species lead to skin aging via oxidative damage that are induced by UV radiation. Therefore, topical formulations which have antioxidant effect could reduce aging level. Astaxanthin is an antioxidant substance.

Efficient synthesis and first regioselective C-6 direct arylation of imidazo[2,1- c ][1,2,4]triazine scaffold and their evaluation in H 2 O 2 -induced oxidative stress

Oxidative stress and apoptosis are both associated with various acute and chronic disorders. Thus, the aim of the present study is to synthesize imidazo[2,1-c][1,2,4]triazines derivatives and to evaluate their effects in H2O2-induced oxidative stress in human neuroblastoma cell line (SH-SY5Y cells). The effects of the compounds on cell viability were measured by MTT assay and the changes in stress and apoptosis-related proteins were investigated by PathScan® Stress and Apoptosis Signaling Antibody Array kit and Western Blot technique. In particular, four compounds were found to protect SH-SY5Y cells from H2O2-induced toxicity by increasing Bcl-2/Bax ratio, regulating PI3-K/Akt cascade and inhibiting the ERK pathway.

Synthesis, biological evaluation, and docking studies of some 5-chloro-2(3H)-benzoxazolone Mannich bases derivatives as cholinesterase inhibitors

A series of N‐substituted‐5‐chloro‐2(3H)‐benzoxazolone derivatives were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory, and antioxidant activities. The structures of the title compounds were confirmed by spectral and elemental analyses. The cholinesterase (ChE) inhibitory activity studies were carried out using Ellmans colorimetric method. The free radical scavenging activity was also determined by in vitro ABTS (2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid)) assay. The biological activity results revealed that all of the title compounds displayed higher AChE inhibitory activity than the reference compound, rivastigmine, and were selective for AChE. Among the tested compounds, compound 7 exhibited the highest inhibition against AChE (IC50 = 7.53 ± 0.17 μM), while compound 11 was found to be the most active compound against BuChE (IC50 = 17.50 ± 0.29 μM). The molecular docking study of compound 7 showed that this compound can interact with the catalytic active site (CAS) of AChE and also has potential metal chelating ability and a proper log P value. On the other hand, compound 2 bearing a methyl substituent at the ortho position on the phenyl ring showed better radical scavenging activity (IC50 = 1.04 ± 0.04 mM) than Trolox (IC50 = 1.50 ± 0.05 mM).

Synthesis, biological activity screening and molecular modeling study of acylaminoacetamide derivatives

In this study, non-rigid analogs of thalidomide have been designed in order to develop potentially active, more effective and safer lead molecules for disorders caused or contributed by inflammation. Five different series of acylaminoacetamide compounds were synthesized, and the biological inhibitory potency of the title compounds has been determined by evaluating their effects on COX-2 isoenzyme expression and PGE2 production in A549 (human lung adenocarcinoma) cell lines. Among the studied series, N-[2-(isopropylamino)-2-oxoethyl]isonicotinamide is the most active inhibitory compound on COX-2 isoenzyme expression, and N-[2-oxo-2-(pyrolydine-1-yl)etyl]isonicotinamide is the most active inhibitory compound on the biosynthesis of PGE2. Molecular docking studies and molecular dynamics simulations were also applied to investigate non-covalent interactions of the most active compounds inside the active side of the crystal structure of murine cyclooxygenase 2 (mCOX-2) isoenzyme.