RNA-guided CRISPR-Cas technologies for genome-scale investigation of disease processes

From its discovery as an adaptive bacterial and archaea immune system, the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system has quickly been developed into a powerful and groundbreaking programmable nuclease technology for the global and precise editing of the genome in cells. This system allows for comprehensive unbiased functional studies and is already advancing the field by revealing genes that have previously unknown roles in disease processes. In this review, we examine and compare recently developed CRISPR-Cas platforms for global genome editing and examine the advancements these platforms have made in guide RNA design, guide RNA/Cas9 interaction, on-target specificity, and target sequence selection. We also explore some of the exciting therapeutic potentials of the CRISPR-Cas technology as well as some of the innovative new uses of this technology beyond genome editing

Histone 4 lysine 20 tri-methylation: a key epigenetic regulator in chromatin structure and disease

Chromatin is a vital and dynamic structure that is carefully regulated to maintain proper cell homeostasis. A great deal of this regulation is dependent on histone proteins which have the ability to be dynamically modified on their tails via various post-translational modifications (PTMs). While multiple histone PTMs are studied and often work in concert to facilitate gene expression, here we focus on the tri-methylation of histone H4 on lysine 20 (H4K20me3) and its function in chromatin structure, cell cycle, DNA repair, and development. The recent studies evaluated in this review have shed light on how H4K20me3 is established and regulated by various interacting partners and how H4K20me3 and the proteins that interact with this PTM are involved in various diseases. Through analyzing the current literature on H4K20me3 function and regulation, we aim to summarize this knowledge and highlights gaps that remain in the field

Identifying the Effects of Unprocessed let-7a-1 and let-7a-3 in Non-Small Cell Lung Cancer

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate protein levels typically by interacting with the 3′ untranslated region (3′-UTR) of target messenger RNA (mRNAs) and are often aberrantly expressed in cancer. The let-7 miRNA family members are commonly regarded as cancer suppressors, by down-regulating the expression of oncoproteins such as RAS, HMGA2, and MYC. However, prior work indicates that unprocessed let-7 RNAs may be positively correlated with cancer phenotypes in lung cancer cell lines. Our study aims to identify the effects of unprocessed let-7a-1 and let-7a-3 in non-small cell lung cancer, by transfecting plasmids that express unprocessed let-7a-1 and let-7a-3 into 3 different lung cancer cell lines. We then proceeded to conduct functional assays to measure the differences in anchorage independent growth, cell proliferation, and cell migration in all cell lines transfected with unprocessed let-7, in contrast to cells transfected with a control vector and thus far determined that unprocessed let-7a-1 can enhance anchorage independent growth. Thus, we created truncations of the let-7a-1 miRNA to identify the cis regions of this miRNA that is responsible for the change in phenotype. Our results suggest that cells transfected with truncated, yet unprocessed let-7a-1 have increased anchorage independent growth, a major hallmark of cancer cell. There is still a need to replicate the functional assays that were conducted while continuing to create constructs of both let-7a-1 and let-7a-3 in order to further identify the sequence of the miRNAs responsible for the enhanced cancer phenotypes

MicroRNA-223 Suppresses the Canonical NF-kB Pathway in Basal Keratinocytes to Dampen Neutrophilic Inflammation

MicroRNA-223 is known as a myeloid-enriched anti-inflammatory microRNA that is dysregulated in numerous inflammatory conditions. Here, we report that neutrophilic inflammation (wound response) is augmented in miR-223-deficient zebrafish, due pri- marily to elevated activation of the canonical nuclear factor kB (NF-kB) pathway. NF-kB over-activation is restricted to the basal layer of the surface epithelium, although miR-223 is detected throughout the epithe- lium and in phagocytes. Not only phagocytes but also epithelial cells are involved in miR-223-medi- ated regulation of neutrophils’ wound response and NF-kB activation. Cul1a/b, Traf6, and Tab1 are iden- tified as direct targets of miR-223, and their levels rise in injured epithelium lacking miR-223. In addi- tion, miR-223 is expressed in cultured human bron- chial epithelial cells, where it also downregulates NF-kB signaling. Together, this direct connection between miR-223 and the canonical NF-kB pathway provides a mechanistic understanding of the multi- faceted role of miR-223 and highlights the relevance of epithelial cells in dampening neutrophil activation

Opportunities to integrate new approaches in genetic toxicology: An ILSI-HESI workshop report

Genetic toxicity tests currently used to identify and characterize potential human mutagens and carcinogens rely on measurements of primary DNA damage, gene mutation, and chromosome damage in vitro and in rodents. The International Life Sciences Institute Health and Environmental Sciences Institute (ILSI-HESI) Committee on the Relevance and Follow-up of Positive Results in In Vitro Genetic Toxicity Testing held an April 2012 Workshop in Washington, DC, to consider the impact of new understanding of biology and new technologies on the identification and characterization of genotoxic substances, and to identify new approaches to inform more accurate human risk assessment for genetic and carcinogenic effects. Workshop organizers and speakers were from industry, academe, and government. The Workshop focused on biological effects and technologies that would potentially yield the most useful information for evaluating human risk of genetic damage. Also addressed was the impact that improved understanding of biology and availability of new techniques might have on genetic toxicology practices. Workshop topics included (1) alternative experimental models to improve genetic toxicity testing, (2) Biomarkers of epigenetic changes and their applicability to genetic toxicology, and (3) new technologies and approaches. The ability of these new tests and technologies to be developed into tests to identify and characterize genotoxic agents; to serve as a bridge between in vitro and in vivo rodent, or preferably human, data; or to be used to provide dose response information for quantitative risk assessment was also addressed. A summary of the workshop and links to the scientific presentations are provided.International Life Sciences Institute/Health and Environmental Sciences Institute Committe

MicroRNA-135b promotes cancer progression by acting as a downstream effector of oncogenic pathways in colon cancer

MicroRNA deregulation is frequent in human colorectal cancers (CRCs), but little is known as to whether it represents a bystander event or actually drives tumor progression in vivo. We show that miR-135b overexpression is triggered in mice and humans by APC loss, PTEN/PI3K pathway deregulation, and SRC overexpression and promotes tumor transformation and progression. We show that miR-135b upregulation is common in sporadic and inflammatory bowel disease-associated human CRCs and correlates with tumor stage and poor clinical outcome. Inhibition of miR-135b in CRC mouse models reduces tumor growth by controlling genes involved in proliferation, invasion, and apoptosis. We identify miR-135b as a key downsteam effector of oncogenic pathways and a potential target for CRC treatment

MicroRNAs in Cancer: A Historical Perspective on the Path from Discovery to Therapy

Recent progress in microRNA (miRNA) therapeutics has been strongly dependent on multiple seminal discoveries in the area of miRNA biology during the past two decades. In this review, we focus on the historical discoveries that collectively led to transitioning miRNAs into the clinic. We highlight the pivotal studies that identified the first miRNAs in Caenorhabditis elegans to the more recent reports that have fueled the quest to understand the use of miRNAs as markers for cancer diagnosis and prognosis. In addition, we provide insights as to how unraveling basic miRNA biology has provided a solid foundation for advancing miRNAs, such as miR-34a, therapeutically. We conclude with a brief examination of the current challenges that still need to be addressed to accelerate the path of miRNAs to the clinic: including delivery vehicles, miRNA- and delivery-associated toxicity, dosage, and off target effects

Aberrant Regulation and Function of MicroRNAs in Cancer

Malignant neoplasms are consistently among the top four leading causes of death in all age groups in the United States, despite a concerted effort toward developing novel therapeutic approaches [1]. Our understanding of and therapeutic strategy for treating each of these neoplastic diseases have been improved through decades of research on the genetics, signaling pathways, and cellular biology that govern tumor cell initiation, progression and maintenance. Much of this work has concentrated on post-translational modifications and abnormalities at the DNA level, including point mutations, amplifications/deletions, and chromosomal translocations, and how these aberrant events affect the expression and function of protein-coding genes. Only recently has a novel class of conserved gene regulatory molecules been identified as a major contributor to malignant neoplastic disease. This review focuses on how these small non-coding RNA molecules, termed microRNAs (miRNAs), can function as oncogenes or tumor suppressors, and how the misexpression of miRNAs and dysregulation of factors that regulate miRNAs contribute to the tumorigenic process. Specific focus is given to more recently discovered regulatory mechanisms that go awry in cancer, and how these changes alter miRNA expression, processing, and function