Abl depletion via autophagy mediates the beneficial effects of quercetin against Alzheimer pathology across species

Alzheimer's disease is the most common age-associated neurodegenerative disorder and the most frequent form of dementia in our society. Aging is a complex biological process concurrently shaped by genetic, dietary and environmental factors and natural compounds are emerging for their beneficial effects against age-related disorders. Besides their antioxidant activity often described in simple model organisms, the molecular mechanisms underlying the beneficial effects of different dietary compounds remain however largely unknown. In the present study, we exploit the nematode Caenorhabditis elegans as a widely established model for aging studies, to test the effects of different natural compounds in vivo and focused on mechanistic aspects of one of them, quercetin, using complementary systems and assays. We show that quercetin has evolutionarily conserved beneficial effects against Alzheimer's disease (AD) pathology: it prevents Amyloid beta (A beta)-induced detrimental effects in different C. elegans AD models and it reduces A beta-secretion in mammalian cells. Mechanistically, we found that the beneficial effects of quercetin are mediated by autophagy-dependent reduced expression of Abl tyrosine kinase. In turn, autophagy is required upon Abl suppression to mediate quercetin's protective effects against A beta toxicity. Our data support the power of C. elegans as an in vivo model to investigate therapeutic options for AD

Rhinella schneideri mucous gland transcriptome

Bibliotecas de produtos naturais são fontes de moléculas com ações farmacológicas, com diversas aplicações biotecnológicas. Estes compostos apresentam alta especificidade para o alvo, resultante de longo processo de seleção natural, sendo interessantes como ferramentas de estudo e princípios ativos. Porém, apesar da riqueza de estruturas presentes em tais secreções, as dificuldades em obter moléculas puras em grandes quantidades, o alto custo e o tempo de purificação, tornam-se barreiras para seu uso. Assim, cada vez mais, as técnicas ômicas são usadas como uma alternativa para produção destas toxinas obtidas em maior escala. A transcriptômica, técnica que consiste na produção de biblioteca de cDNA a partir do RNA obtido da de organismo, tecido ou célula de interesse, é altamente relevante, já que identifica o material proteico que é realmente transcrito a partir do RNA obtido em determinado tempo e situação. Sapos ainda são animais pouco estudados, quando comparados a outros animais peçonhentos e venenosos, e um dos fatores responsáveis por isso é o baixo rendimento na purificação de toxinas de seu veneno. A fim de se identificar componentes presentes nas secreções do sapo R. schneideri, foi, primeiramente, realizada extração de RNA poli A+ das secreções recém obtidas das glândulas mucosas e das secreções armazenadas por 2 anos no laboratório. A secreção armazenada há dois anos revelou qualidade e quantidade mais apropriadas para o estudo e foi, portanto, usada como material de partida para a construção do transcriptoma por metodologia tradicional. Este transcriptoma resultou em 6 clones com boa qualidade, sendo que um deles, Rs02, apresentou similaridade com a região do pró peptídeo da odorranaina. Uma vez que este transcriptoma não revelou resultados satisfatórios devido à sua baixa eficiência e visando maximizar o conhecimento sobre a secreção, um novo transcriptoma foi construído usando sequenciamento de nova geração, com sequenciador Illumina e RNA total extraído do tegumento contendo glândulas mucosas de um espécime como material de partida. O novo transcriptoma resultou em aproximadamente 131 milhões de reads brutos. Os reads foram filtrados de modo que apenas aqueles com boa qualidade (Q>20) fossem submetidos à montagem de novo. Esta etapa resultou em aproximadamente 130 milhões de reads, com média de 68 pb. Os reads foram então agrupados em contigs usando o programa SOAPdenovo2-Trans e submetidos a diversas abordagens de anotação funcional. Foram encontrados cDNAs codificantes de diversos peptídeos e proteínas com potencial aplicação biotecnológica. Além da abordagem ômica, ensaios de caracterização bioquímica, como atividade enzimática, cromatografia e eletroforese, auxiliaram a detecção de protease sem relatos prévios em secreções de sapo, uma fosfolipase A2, bem como lectina e galectina. Adicionalmente, através do transcriptoma foram identificadas cobatoxinas, mucinas e ficolinas. Portanto, este trabalho foi pioneiro no entendimento molecular do veneno da glândula mucosa de R. schneideri por métodos de vanguarda e análises bioquímicas.Natural products libraries are known as medicine molecules sources once these molecules have a high target specificity inherited from the long natural evolutionary process. Thereby, animal, plant and microorganisms\' secretions are very important to biotechnological applications. However, despite the large number of molecules that can be found in these secretions, the difficulty on obtainment enough purification yield, high cost and long purification time, besides the small secretion amount provided by the studied organism, are factors that make this kind of study even harsher. These are the reasons why omic studies are becoming an alternative to produce these toxins in a larger scale, which allow new researches. Transcriptome is a technique that consists on the production of cDNA libraries from the secretion or gland RNA, using the transcriptase reverse enzyme, which results in a holistic poison understanding. Toads are animals that are still not widely studied, if we compare them with other venomous animals, mainly because of the insufficient purification yield. Thus, the mucous gland transcriptome from Rhinella schneideri poison, a toad that is widely found in Brazilian territory, has a great relevance on the elucidation and possibility to use several kind of molecules, especially because this gland produces unknown molecules. Thereof, aiming to unravel this poison molecules, we first compared the RNA yield from fresh and two years stored mucous gland secretion. The stored secretion has shown more suitable RNA, which was used to construct a Sanger sequencing transcriptome. It resulted in 6 clones and one of them had a good hit with odorranain pro-peptide region. In order to increase the knowledge about the secretion, we turned to Next Generation Sequencing transcriptome using Illumina technologies and one specimen integument as raw material. The new transcriptome resulted in approximately 131 million raw reads. These reads were filtered so that only those with good quality (Q>20) were used to perform the assembling. The latter step resulted in approximately 130 million reads with 68 bp average length. The reads were grouped into contigs using the assembler. Then, the resulting contigs were submitted to different functional annotation approaches. We unraveled cDNAs encoding peptides and protein with biotechnological application. Besides the omic approach, assays for biochemical characterization including chromatography, electrophoresis and proteolytic assays complemented the identification of a protease for the first time in toad secretions, phospholipase A2, as much as lectins and galectins. Thus, the transcriptome also allowed the identification of cobatoxins, mucins and ficolins. Therefore, this is the first work about the molecular composition of Rhinella schneideri mucous gland poison through avant-garde methodology and biochemical anaylsis

Identification and Functional Analysis of a Pseudo-Cysteine Protease from the Midgut Transcriptome of Sphenophorus levis

The Sphenophorus levis (Coleoptera, Curculionidae) is one of the main pests of sugarcane in Brazil. Although its major digestive proteases are known, its complex digestive process still needs to be further understood. We constructed a transcriptome from the midgut of 30-day-old larvae and identified sequences similar to its major digestive protease (cysteine cathepsin Sl-CathL), however, they presented a different amino acid than cysteine in the active cleft. We identified, recombinantly produced, and characterized Sl-CathL-CS, a pseudo cysteine protease, and verified that higher gene expression levels of Sl-CathL-CS occur in the midgut of 30-day old larvae. We reverted the serine residue to cysteine and compared the activity of the mutant (Sl-CathL-mutSC) with Sl-CathL-CS. Sl-CathL-CS presented no protease activity, but Sl-CathL-mutSC hydrolyzed Z-Phe-Arg-AMC (Vmax = 1017.60 ± 135.55, Km = 10.77 mM) and was inhibited by a cysteine protease inhibitor E-64 (Ki = 38.52 ± 1.20 μM), but not by the serine protease inhibitor PMSF. Additionally, Sl-CathL-CS interacted with a sugarcane cystatin, while Sl-CathL-mutSC presented weaker interaction. Finally, protein ligand docking reinforced the differences in the catalytic sites of native and mutant proteins. These results indicate that Sl-CathL-CS is a pseudo-cysteine protease that assists protein digestion possibly by interacting with canecystatins, allowing the true proteases to work

Deep sequencing analysis of toad Rhinella schneideri skin glands and partial biochemical characterization of its cutaneous secretion

Abstract Background Animal poisons and venoms are sources of biomolecules naturally selected. Rhinella schneideri toads are widespread in the whole Brazilian territory and they have poison glands and mucous gland. Recently, protein from toads’ secretion has gaining attention. Frog skin is widely known to present great number of host defense peptides and we hypothesize toads present them as well. In this study, we used a RNA-seq analysis from R. schneideri skin and biochemical tests with the gland secretion to unravel its protein molecules. Methods Total RNA from the toad skin was extracted using TRizol reagent, sequenced in duplicate using Illumina Hiseq2500 in paired end analysis. The raw reads were trimmed and de novo assembled using Trinity. The resulting sequences were submitted to functional annotation against non-redundant NCBI database and Database of Anuran Defense Peptide. Furthermore, we performed caseinolytic activity test to assess the presence of serine and metalloproteases in skin secretion and it was fractionated by fast liquid protein chromatography using a reverse-phase column. The fractions were partially sequenced by Edman’s degradation. Results We were able to identify several classes of antimicrobial peptides, such as buforins, peroniins and brevinins, as well as PLA2, lectins and galectins, combining protein sequencing and RNA-seq analysis for the first time. In addition, we could isolate a PLA2 from the skin secretion and infer the presence of serine proteases in cutaneous secretion. Conclusions We identified novel toxins and proteins from R. schneideri mucous glands. Besides, this is a pioneer study that presented the in depth characterization of protein molecules richness from this toad secretion. The results obtained herein showed evidence of novel AMP and enzymes that need to be further explored