Project description:We identified Tf2, the first β-scorpion toxin from the venom of the Brazilian scorpion Tityus fasciolatus. Tf2 is identical to Tb2-II found in Tityus bahiensis. We found that Tf2 selectively activates human (h)Nav1.3, a neuronal voltage-gated sodium (Nav) subtype implicated in epilepsy and nociception. Tf2 shifts hNav1.3 activation voltage to more negative values, thereby opening the channel at resting membrane potentials. Seven other tested mammalian Nav channels (Nav1.1-1.2; Nav1.4-1.8) expressed in Xenopus oocytes are insensitive upon application of 1 μM Tf2. Therefore, the identification of Tf2 represents a unique addition to the repertoire of animal toxins that can be used to investigate Nav channel function.
Project description:Scorpion venoms are a complex mixture of components. Among them the most important are peptides, which presents the capacity to interact and modulate several ion channel subtypes, including voltage-gated sodium channels (NaV). Screening the activity of scorpion toxins on different subtypes of NaV reveals the scope of modulatory activity and, in most cases, low channel selectivity. Until now there are approximately 60 scorpion toxins experimentally assayed on NaV channels. However, the molecular bases of interaction between scorpion toxins and NaV channels are not fully elucidated. The activity description of new scorpion toxins is crucial to enhance the predictive strength of the structural⁻function correlations of these NaV modulatory molecules. In the present work a new scorpion toxin (Tf1a) was purified from Tityus fasciolatus venom by RP-HPLC, and characterized using electrophysiological experiments on different types of voltage-gated sodium channels. Tf1a was able to modify the normal function of NaV tested, showing to be a typical β-NaScTx. Tf1a also demonstrated an unusual capability to alter the kinetics of NaV1.5.
Project description:Hundreds of toxins, particularly from scorpions of lesser medical significance, remain unknown, especially those from species endemic to specific ecosystems, such as Tityus fasciolatus. Their discovery could contribute to the development of new drugs for channelopathies and other diseases. Tf5 is a new peptide that has been identified from the venom of Tityus fasciolatus, a scorpion species endemic to the Brazilian Cerrado ecosystem. A full-length cDNA sequence of the Tf5 gene was obtained through a previously constructed transcriptomic library, where an ORF (Open Reading Frame) sequence with a length of 180 was found, including the 37 aa mature KTx domain, which has six Cys residues. Tf5 was purified from the crude venom, resulting in a peptide with a molecular mass of 3983.95 Da. Its K+ channel blocker activity was evaluated on Kv1.1, Kv1.2, Kv1.3, and Kv1.4 subtypes. Of these Kv channels, the peptide demonstrated an ability to block Kv1.2 and Kv1.3 with an IC50 of 15.53 nM and 116.41 nM, respectively. Additionally, Tf5 shares a high degree of sequence identity with toxins from the α-KTx4 subfamily, which led to it being classified as α-KTx4.9. This is the first Kv channel blocker described from the T. fasciolatus scorpion.
Project description:This study aims to investigate the DNA methylation patterns at transcription factor binding regions and their evolutionary conservation with respect to binding activity divergence. We combined newly generated bisulfite-sequencing experiments in livers of five mammals (human, macaque, mouse, rat and dog) and matched publicly available ChIP-sequencing data for five transcription factors (CEBPA, HNF4a, CTCF, ONECUT1 and FOXA1). To study the chromatin contexts of TF binding subjected to distinct evolutionary pressures, we integrated publicly available active promoter, active enhancer and primed enhancer calls determined by profiling genome wide patterns of H3K27ac, H3K4me3 and H3K4me1.
Project description:Whole genome sequencing of the Arabidopsis thaliana dot5-1 transposon insertion line described in Petricka et al 2008 The Plant Journal 56(2): 251-263.
