13 research outputs found

    Acyl-Protein Thioesterase 2 Catalizes the Deacylation of Peripheral Membrane-Associated GAP-43

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    An acylation/deacylation cycle is necessary to maintain the steady-state subcellular distribution and biological activity of S-acylated peripheral proteins. Despite the progress that has been made in identifying and characterizing palmitoyltransferases (PATs), much less is known about the thioesterases involved in protein deacylation. In this work, we investigated the deacylation of growth-associated protein-43 (GAP-43), a dually acylated protein at cysteine residues 3 and 4. Using fluorescent fusion constructs, we measured in vivo the rate of deacylation of GAP-43 and its single acylated mutants in Chinese hamster ovary (CHO)-K1 and human HeLa cells. Biochemical and live cell imaging experiments demonstrated that single acylated mutants were completely deacylated with similar kinetic in both cell types. By RT-PCR we observed that acyl-protein thioesterase 1 (APT-1), the only bona fide thioesterase shown to mediate deacylation in vivo, is expressed in HeLa cells, but not in CHO-K1 cells. However, APT-1 overexpression neither increased the deacylation rate of single acylated GAP-43 nor affected the steady-state subcellular distribution of dually acylated GAP-43 both in CHO-K1 and HeLa cells, indicating that GAP-43 deacylation is not mediated by APT-1. Accordingly, we performed a bioinformatic search to identify putative candidates with acyl-protein thioesterase activity. Among several candidates, we found that APT-2 is expressed both in CHO-K1 and HeLa cells and its overexpression increased the deacylation rate of single acylated GAP-43 and affected the steady-state localization of diacylated GAP-43 and H-Ras. Thus, the results demonstrate that APT-2 is the protein thioesterase involved in the acylation/deacylation cycle operating in GAP-43 subcellular distribution

    Interspecies Chemical Signals Released into the Environment May Create Xenohormetic, Hormetic and Cytostatic Selective Forces that Drive the Ecosystemic Evolution of Longevity Regulation Mechanisms

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    Various organisms (i.e., bacteria, fungi, plants and animals) within an ecosystem can synthesize and release into the environment certain longevity-extending small molecules. Here we hypothesize that these interspecies chemical signals can create xenohormetic, hormetic and cytostatic selective forces driving the ecosystemic evolution of longevity regulation mechanisms. In our hypothesis, following their release into the environment by one species of the organisms composing an ecosystem, such small molecules can activate anti-aging processes and/or inhibit pro-aging processes in other species within the ecosystem. The organisms that possess the most effective (as compared to their counterparts of the same species) mechanisms for sensing the chemical signals produced and released by other species and for responding to such signals by undergoing certain hormetic and/or cytostatic life-extending changes to their metabolism and physiology are expected to live longer then their counterparts within the ecosystem. Thus, the ability of a species of the organisms composing an ecosystem to undergo life-extending metabolic or physiological changes in response to hormetic or cytostatic chemical compounds released to the ecosystem by other species: 1) increases its chances of survival; 2) creates selective forces aimed at maintaining such ability; and 3) enables the evolution of longevity regulation mechanisms

    Increased expression of cellular retinol-binding protein 1 in laryngeal squamous cell carcinoma

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    PURPOSE: To investigate the genomic alterations in larynx carcinomas (LaCa) tissues and its prognostics values in predicting survival. METHODS: To analyse the aberrations in the genome of LaCa patients, we used array comparative genomic hybridization in 19 human laryngeal tumour samples. DNA samples were also subjected to detect human papillomavirus (HPV) sequences by polymerase chain reaction (PCR). Copy number gain was confirmed by real-time PCR. The cellular retinol-binding protein 1 (CRBP-1) gene expression was also confirmed by immunohistochemistry assay on LaCa tissues. To identify prognostic feature, CRBP-1 gene gain was correlated to patient survival. RESULTS: The most common gains were detected for CRBP-1 and EGFR genes, while DNA lost in RAF-1 gene. Immunohistochemistry assay was revealed strong expression of CRBP1 protein in those cases with CRBP-1 gene gain. The CRBP-1 gene gain and its expression correlated significantly with survival (P = 0.003). Cox regression analysis indicated that CRBP-1 expression level was a factor of survival (P = 0.008). HPV sequences were detected in 42% of the samples, and did not show any relationship with specific gene alterations. CONCLUSION: Our data shows that CRBP-1 gene gain can be determined by immunohistochemistry on routinely processed tissue specimens, and could support as a potential novel marker for long-term survival in laryngeal squamous cell carcinoma
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