Transcutaneous spinal direct current stimulation increases corticospinal transmission and enhances voluntary motor output in humans

Optimization of motor performance is of importance in daily life, in relation to recovery following injury as well as for elite sports performance. The present study investigated whether transcutaneous spinal direct current stimulation (tsDCS) may enhance voluntary ballistic activation of ankle muscles and descending activation of spinal motor neurons in able‐bodied adults. Forty‐one adults (21 men; 24.0 ± 3.2 years) participated in the study. The effect of tsDCS on ballistic motor performance and plantar flexor muscle activation was assessed in a double‐blinded sham‐controlled cross‐over experiment. In separate experiments, the underlying changes in excitability of corticospinal and spinal pathways were probed by evaluating soleus (SOL) motor evoked potentials (MEPs) following single‐pulse transcranial magnetic stimulation (TMS) over the primary motor cortex, SOL H‐reflexes elicited by tibial nerve stimulation and TMS‐conditioning of SOL H‐reflexes. Measures were obtained before and after cathodal tsDCS over the thoracic spine (T11‐T12) for 10 min at 2.5 mA. We found that cathodal tsDCS transiently facilitated peak acceleration in the ballistic motor task compared to sham tsDCS. Following tsDCS, SOL MEPs were increased without changes in H‐reflex amplitudes. The short‐latency facilitation of the H‐reflex by subthreshold TMS, which is assumed to be mediated by the fast conducting monosynaptic corticomotoneuronal pathway, was also enhanced by tsDCS. We argue that tsDCS briefly facilitates voluntary motor output by increasing descending drive from corticospinal neurones to spinal plantar flexor motor neurons. tsDCS can thus transiently promote within‐session CNS function and voluntary motor output and holds potential as a technique in the rehabilitation of motor function following central nervous lesions

Gel-Free Tools for Quick and Simple Screening of Anti-Topoisomerase 1 Compounds

With the increasing need for effective compounds against cancer or pathogen-borne diseases, the development of new tools to investigate the enzymatic activity of biomarkers is necessary. Among these biomarkers are DNA topoisomerases, which are key enzymes that modify DNA and regulate DNA topology during cellular processes. Over the years, libraries of natural and synthetic small-molecule compounds have been extensively investigated as potential anti-cancer, anti-bacterial, or anti-parasitic drugs targeting topoisomerases. However, the current tools for measuring the potential inhibition of topoisomerase activity are time consuming and not easily adaptable outside specialized laboratories. Here, we present rolling circle amplification-based methods that provide fast and easy readouts for screening of compounds against type 1 topoisomerases. Specific assays for the investigation of the potential inhibition of eukaryotic, viral, or bacterial type 1 topoisomerase activity were developed, using human topoisomerase 1, Leishmania donovani topoisomerase 1, monkeypox virus topoisomerase 1, and Mycobacterium smegmatis topoisomerase 1 as model enzymes. The presented tools proved to be sensitive and directly quantitative, paving the way for new diagnostic and drug screening protocols in research and clinical settings.This research was funded in part by the Ministerio de Ciencia e Innovación, Spain (PID2021-122558OB-I00, UE) and by Gobierno Vasco, Universidad del País Vasco (GV, IT1701-22; UPV)

Topoisomerase 1 inhibits MYC promoter activity by inducing G-quadruplex formation

We have investigated the function of human topoisomerase 1 (TOP1) in regulation of G-quadruplex (G4) formation in the Pu27 region of the MYC P1 promoter. Pu27 is among the best characterized G4 forming sequences in the human genome and it is well known that promoter activity is inhibited upon G4 formation in this region. We found that TOP1 downregulation stimulated transcription from a promoter with wildtype Pu27 but not if the G4 motif in Pu27 was interrupted by mutation(s). The effect was not specific to the MYC promoter and similar results were obtained for the G4 forming promoter element WT21. The other major DNA topoisomerases with relaxation activity, topoisomerases 2α and β, on the other hand, did not affect G4 dependent promoter activity. The cellular studies were supported by in vitro investigations demonstrating a high affinity of TOP1 for wildtype Pu27 but not for mutant sequences unable to form G4. Moreover, TOP1 was able to induce G4 formation in Pu27 inserted in double stranded plasmid DNA in vitro. This is the first time TOP1 has been demonstrated capable of inducing G4 formation in double stranded DNA and of influencing G4 formation in cells