MicroRNA: A Tiny Molecule Yields Big Insights Into Disease States

Regular readers of this column will know that there are two main categories of nucleic acids—DNA and RNA. They’ll also know that while for living organisms DNA acts as the genetic data repository, RNA has a messenger role (mRNAs, transcribed from DNA to direct protein synthesis). Most will also recall that there are other classes of RNA molecules, particularly tRNAs (used to tag and identify amino acids for protein synthesis) and rRNAs (structural components of the ribosome, the cellular “machinery” for protein synthesis). In addition to these, there’s increasing interest in the molecular diagnostics community in a less widely known but no less common RNA form, the microRNA or miRNA.

Read more: MicroRNA: A Tiny Molecule Yields Big Insights Into Disease States

Source: MedicalLaboratoryObserver

The Role of Diet and Exercise in the Transgenerational Epigenetic Landscape of T2DM

Epigenetic changes are caused by biochemical regulators of gene expression that can be transferred across generations or through cell division. Epigenetic modifications can arise from a variety of environmental exposures including undernutrition, obesity, physical activity, stress and toxins. Transient epigenetic changes across the entire genome can influence metabolic outcomes and might or might not be heritable. These modifications direct and maintain the cell-type specific gene expression state. Transient epigenetic changes can be driven by DNA methylation and histone modification in response to environmental stressors. A detailed understanding of the epigenetic signatures of insulin resistance and the adaptive response to exercise might identify new therapeutic targets that can be further developed to improve insulin sensitivity and prevent obesity. This Review focuses on the current understanding of mechanisms by which lifestyle factors affect the epigenetic landscape in type 2 diabetes mellitus and obesity. Evidence from the past few years about the potential mechanisms by which diet and exercise affect the epigenome over several generations is discussed.

Key points

• Epigenetic processes have been implicated in the pathogenesis of type 2 diabetes mellitus
• Diet and exercise might affect the epigenome over several generations
• Epigenetic changes can be driven by DNA methylation and histone modification in response to environmental stressors
• Regulation of gene expression by DNA methylation and histone modification occurs by a mechanism that impairs the access of transcriptional machinery to the promoters
• Studying the epigenetic signatures of insulin resistance and the adaptive response to exercise might provide insight into gene–environment networks that control glucose and energy homeostasis.

Read more: The Role of Diet and Exercise in the Transgenerational Epigenetic Landscape of T2DM

Figure 2: Putative effects of exercise and obesity on the predisposition to metabolic diseases.

Source: NatureReviewsEndocrinology

Written in Blood

A tour of evolving strategies for identifying circulating disease biomarkers

Blood is the only tissue that makes contact with every organ in the body. Theoretically, probing the DNA, RNA, vesicles, and cellular debris it carries could help diagnose or monitor conditions from placental disorders to Alzheimer’s disease.

The first application of this approach was prenatal genetic screening—which analyzes fragments of fetal DNA in an expectant mother’s blood—available to clinicians since October 2011. So far, these tests have largely focused on identifying chromosomal abnormalities such as Down syndrome. But expanding their utility to monitoring other circulating biomarkers, such as RNA and the contents of membrane-bound microvesicles and exosomes, is on the rise.

Read more: Written in Blood

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Source: theScientist

Rapid Detection of Urinary Biomarkers with Novel Optical Device

A compact optical device has been developed that can rapidly and sensitively detect biomarkers in urine and has promise for developing simple point-of-care diagnostics of cancer and other diseases.

Micro ribonucleic acids (miRNAs) are a newly discovered class of short, about 19 to 24 nucleotides in length, fragments of noncoding RNAs that are useful biomarkers for diagnosing various diseases, including cardiac disease and some cancers. Since they are surprisingly well preserved in fluids such as urine and blood, their detection is well suited to a rapid, point-of-care method.

Bioengineers at the Agency for Science, Technology and Research (Singapore) have devised a silicon photonic biosensor that can detect tiny changes in the phase of a light beam caused by hybridization between an immobilized DNA probe and target miRNAs in a sample. A laser beam travels through a waveguide, which splits into two arms: a sensing arm in which the light interacts with the sample and a reference arm.

Read more: Rapid Detection of Urinary Biomarkers with Novel Optical Device

Image: Schematic diagram of the MZI biosensor system for miRNA detection.

(a) TEM image of the cross section of a silicon nitride slot wave guide; SEM images of

(b) a strip-slot wave guide mode converter and (c) a silicon nitride grating coupler.

(d) Image of MZI biosensor platform

Source: Agency for Science, Technology and Research