Quantitative model of R-loop forming structures reveals a novel level of RNA–DNA interactome complexity

R-loop is the structure co-transcriptionally formed between nascent RNA transcript and DNA template, leaving the non-transcribed DNA strand unpaired. This structure can be involved in the hyper-mutation and dsDNA breaks in mammalian immunoglobulin (Ig) genes, oncogenes and neurodegenerative disease related genes. R-loops have not been studied at the genome scale yet. To identify the R-loops, we developed a computational algorithm and mapped R-loop forming sequences (RLFS) onto 66 803 sequences defined by UCSC as ‘known’ genes. We found that ∼59% of these transcribed sequences contain at least one RLFS. We created R-loopDB (http://rloop.bii.a-star.edu.sg/), the database that collects all RLFS identified within over half of the human genes and links to the UCSC Genome Browser for information integration and visualisation across a variety of bioinformatics sources. We found that many oncogenes and tumour suppressors (e.g. Tp53, BRCA1, BRCA2, Kras and Ptprd) and neurodegenerative diseases related genes (e.g. ATM, Park2, Ptprd and GLDC) could be prone to significant R-loop formation. Our findings suggest that R-loops provide a novel level of RNA–DNA interactome complexity, playing key roles in gene expression controls, mutagenesis, recombination process, chromosomal rearrangement, alternative splicing, DNA-editing and epigenetic modifications. RLFSs could be used as a novel source of prospective therapeutic targets

Desenvolvimento de um método de deteção de CNVs através de qPCR

Mestrado em BiotecnologiaOs copy number variations (CNVs) consistem em segmentos de DNA de uma kilobase ou mais, que se encontram num número variável de cópias, em comparação com um genoma de referência. A deteção de CNVs é convencionalmente realizada através de técnicas de citogenética, como fluorescence in situ hybridization e array comparative genomic hybridization, ou com base em PCR, como multiplex ligation-dependent probe amplification, SNP arrays ou deep sequencing. Porém, a evolução da técnica de PCR quantitativo em tempo real (qPCR) permitiu que fosse, actualmente, considerada o método gold standard para a detecção de CNVs devido, sobretudo, ao elevado rendimento, sensibilidade, precisão e versatilidade. O presente trabalho descreve o desenvolvimento e validação de um método de deteção de CNVs através da técnica de qPCR. A metodologia adotada provou ser um método preciso e sensível para a detecção de CNVs em regiões específicas.Copy number variations (CNVs) consist in DNA segments of one kilobase or larger, that are present in variable copy number, in comparison to a reference genome. CNVs detection is conventionally performed through cytogenetic, such as fluorescence in situ hybridization and array comparative genomic hybridization, or PCR-based techniques, like multiplex ligation-dependent probe amplification, SNP arrays or deep sequencing. However, the evolution of quantitative PCR (qPCR) allows it to be considered the gold standard for CNVs detection, mainly due to its high throughput, precision and versatility. The present work describes the development and validation of a qPCR method for CNVs detection. This method proved to be an accurate and sensitive method for CNVs detection in targeted regions

Key Issues in Essential Tremor Genetics Research: Where Are We Now and How Can We Move Forward?

Background: Genetics research is an avenue towards understanding essential tremor (ET). Advances have been made in genetic linkage and association: there are three reported ET susceptibility loci, and mixed but growing data on risk associations. However, causal mutations have not been forthcoming. This disappointing lack of progress has opened productive discussions on challenges in ET and specifically ET genetics research, including fundamental assumptions in the field. Methods: This article reviews the ET genetics literature, results to date, the open questions in ET genetics and the current challenges in addressing them. Results: Several inherent ET features complicate genetic linkage and association studies: high potential phenocopy rates, inaccurate tremor self-reporting, and ET misdiagnoses are examples. Increasing use of direct examination data for subjects, family members, and controls is one current response. Smaller moves towards expanding ET phenotype research concepts into non-tremor features, clinically disputed ET subsets, and testing phenotype features instead of clinical diagnosis against genetic data are gradually occurring. The field has already moved to considering complex trait mechanisms requiring detection of combinations of rare genetic variants. Hypotheses may move further to consider novel mechanisms of inheritance, such as epigenetics. Discussion: It is an exciting time in ET genetics as investigators start moving past assumptions underlying both phenotype and genetics experimental contributions, overcoming challenges to collaboration, and engaging the ET community. Multicenter collaborative efforts comprising rich longitudinal prospective phenotype data and neuropathologic analysis combined with the latest in genetics experimental design and technology will be the next wave in the field

The Multifaceted Roles of Autophagy in Infectious, Obstructive, and Malignant Airway Diseases

Autophagy is a highly conserved dynamic process by which cells deliver their contents to lysosomes for degradation, thus ensuring cell homeostasis. In response to environmental stress, the induction of autophagy is crucial for cell survival. The dysregulation of this degradative process has been implicated in a wide range of pathologies, including lung diseases, representing a relevant potential target with significant clinical outcomes. During lung disease progression and infections, autophagy may exert both protective and harmful effects on cells. In this review, we will explore the implications of autophagy and its selective forms in several lung infections, such as SARS-CoV-2, Respiratory Syncytial Virus (RSV) and Mycobacterium tuberculosis (Mtb) infections, and different lung diseases such as Cystic Fibrosis (CF), Chronic Obstructive Pulmonary Disease (COPD), and Malignant Mesothelioma (MM)

New Advances in Melanoma

Melanoma is a very aggressive tumor which is derived from the transformation of pigment-producing cells termed the melanocytes. This cancer type accounts for most of the deaths associated with skin cancer as well as its incidence and is in constant evolution. Because of the rapid and very high metastatic potential of this tumor, melanoma prognosis has been quite poor for a long time. In the past decade, groundbreaking discoveries in the melanoma research field have led to the development of two main treatment strategies: combination therapies targeting specific kinases or combination therapies focused on immune checkpoint inhibitors (ICIs). These treatment approaches have become the standard of care in most cancer centers and significantly improved the prognosis and overall survival of advanced melanoma patients. Nevertheless, many patients do not benefit from or even respond to these treatments. It is therefore essential to better comprehend the phenomenon of drug resistance, immune escape mechanisms, as well as to search for alternative treatment strategies. In addition, strong predictive biomarkers are desperately needed to improve clinical efficacy. The aim of this Special Issue is to present recent advances in the field of melanoma research, in which the abovementioned areas represent the primary focus, and other relevant themes are also discussed

Comprehensive genomic profiles of small cell lung cancer

We have sequenced the genomes of 110 small cell lung cancers (SCLC), one of the deadliest human cancers. In nearly all the tumours analysed we found bi-allelic inactivation of TP53 and RB1, sometimes by complex genomic rearrangements. Two tumours with wild-type RB1 had evidence of chromothripsis leading to overexpression of cyclin D1 (encoded by the CCND1 gene), revealing an alternative mechanism of Rb1 deregulation. Thus, loss of the tumour suppressors TP53 and RB1 is obligatory in SCLC. We discovered somatic genomic rearrangements of TP73 that create an oncogenic version of this gene, TP73Dex2/3. In rare cases, SCLC tumours exhibited kinase gene mutations, providing a possible therapeutic opportunity for individual patients. Finally, we observed inactivating mutations in NOTCH family genes in 25% of human SCLC. Accordingly, activation of Notch signalling in a pre-clinical SCLC mouse model strikingly reduced the number of tumours and extended the survival of the mutant mice. Furthermore, neuroendocrine gene expression was abrogated by Notch activity in SCLC cells. This first comprehensive study of somatic genome alterations in SCLC uncovers several key biological processes and identifies candidate therapeutic targets in this highly lethal form of cancer