Australian researchers have demonstrated a strong association between the FTO (fat and obesity) gene and hip fracture in women. While the gene is already well known to affect diabetes and body fat, this is the first study to show that its high-risk variant can increase the risk of hip fracture by as much as 82%.
The study, undertaken by Dr Bich Tran and Professor Tuan Nguyen from Sydney’s Garvan Institute of Medical Research, examined six gene variants (single nucleotide polymorphisms, or SNPs) of the FTO gene, taken from the DNA of 943 women in the Dubbo Osteoporosis Epidemiology Study (DOES). The women were all over 60, and their bone health was followed between 1989 and 2007. During that period, 102 women had hip fractures.
On average, the risk of fracture is about 11%. The study showed that if a woman has a low-risk genotype, or gene variant, the risk of fracture is 10%. If she has a high-risk genotype, it is 16%.
The authors believe that the findings have the potential to improve prediction of hip fracture. Known risk factors, also to be taken into account, include advancing age, falls, history of fracture, low bone mineral density, low body mass index (BMI) and genetic make-up.
‘We found that for a woman of the same age and same clinical risk factors, those with the high-risk genotype have an increased risk of fracture of 82% – a very high effect in genetic terms,’ said Professor Tuan Nguyen.
‘A genome-wide association study published in 2007 suggested that genetic variants in the FTO gene were associated with variation in BMI. This led us to hypothesise that they might also be associated with variation in hip fracture risk.’
‘The present study tested our hypothesis by examining the association between common variants in the FTO gene and hip fracture.’
‘Our results showed a strong association with hip fracture, with some gene variants doubling the risk of fracture. Interestingly, this was independent of both the bone density and BMI of the women we studied.’
‘We also found that the FTO gene expresses in bone cells, and may have something to do with bone turnover, or remodelling, although its exact mechanisms are unclear.’
‘It’s important to emphasise that, while promising, our finding is a first step. It will need to be replicated in other studies, and its mechanisms clearly understood before it is useful in drug development.’ Garvan Institute of Medical Research

Researchers with the UC Davis MIND Institute and Agilent Laboratories have found that Prader-Willi syndrome — a genetic disorder best known for causing an insatiable appetite that can lead to morbid obesity — is associated with the loss of non-coding RNAs, resulting in the dysregulation of circadian and metabolic genes, accelerated energy expenditure and metabolic differences during sleep.
The research was led by Janine LaSalle, a professor in the UC Davis Department of Medical Microbiology and Immunology who is affiliated with the MIND Institute. It is published online in Human Molecular Genetics.
‘Prader-Willi syndrome children do not sleep as well at night and have daytime sleepiness,’ LaSalle said. ‘Parents have to lock up their pantries because the kids are rummaging for food in the middle of the night, even breaking into their neighbours’ houses to eat.’
The study found that these behaviours are rooted in the loss of a long non-coding RNA that functions to balance energy expenditure in the brain during sleep. The finding could have a profound effect on how clinicians treat children with Prader-Willi, as well as point the way to new, innovative therapies, LaSalle said.
The leading cause of morbid obesity among children in the United States, Prader-Willi involves a complex, and sometimes contradictory, array of symptoms. Shortly after birth children with Prader-Willi experience failure to thrive. Yet after they begin to feed themselves, they have difficulty sleeping and insatiable appetites that lead to obesity if their diets are not carefully monitored.
The current study was conducted in a mouse model of Prader-Willi syndrome. It found that mice engineered with the loss of a long non-coding RNA showed altered energy use and metabolic differences during sleep.
Prader-Willi has been traced to a specific region on chromosome 15 (SNORD116), which produces RNAs that regulate gene expression, rather than coding for proteins. When functioning normally, SNORD116 produces small nucleolar (sno) RNAs and a long non-coding RNA (116HG), as well as a third non-coding RNA implicated in a related disorder, Angelman syndrome. The 116HG long non-coding RNA forms a cloud inside neuronal nuclei that associates with proteins and genes regulating diurnal metabolism in the brain, LaSalle said.
‘We thought the cloud would be activating transcription, but in fact it was doing the opposite,’ she said. ‘Most of the genes were dampened by the cloud. This long non-coding RNA was acting as a decoy, pulling the active transcription factors away from genes and keeping them from being expressed.’
As a result, losing snoRNAs and 116HG causes a chain reaction, eliminating the RNA cloud and allowing circadian and metabolic genes to get turned on during sleep periods, when they should be dampened down. This underlies a complex cycle in which the RNA cloud grew during sleep periods (daytime for nocturnal mice), turning down genes associated with energy use, and receded during waking periods, allowing these genes to be expressed. Mice without the 116HG gene lacked the benefit of this neuronal cloud, causing greater energy expenditure during sleep.
The researchers said that the work provides a clearer picture of why children with Prader-Willi syndrome can’t sleep or feel satiated and may change therapeutic approaches. For example, many such children have been treated with growth hormone because of short stature, but this actually may boost other aspects of the disease.
‘People had thought the kids weren’t sleeping at night because of the sleep apnea caused by obesity,’ said LaSalle. ‘What this study shows is that the diurnal metabolism is central to the disorder, and that the obesity may be as a result of that. If you can work with that, you could improve therapies, for example figuring out the best times to administer medications.’ UC Davis Department of Medical Microbiology and Immunology

A team of cardiovascular researchers from the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai, Sanford-Burnham Medical Research Institute, and University of California, San Diego have identified a small, but powerful, new player in the onset and progression of heart failure. Their findings also show how they successfully blocked the newly discovered culprit to halt the debilitating and chronic life-threatening condition in its tracks.
In the study, investigators identified a tiny piece of RNA called miR-25 that blocks a gene known as SERCA2a, which regulates the flow of calcium within heart muscle cells. Decreased SERCA2a activity is one of the main causes of poor contraction of the heart and enlargement of heart muscle cells leading to heart failure. Using a functional screening system developed by researchers at Sanford-Burnham, the research team discovered miR-25 acts pathologically in patients suffering from heart failure, delaying proper calcium uptake in heart muscle cells.
‘Before the availability of high-throughput functional screening, our chance of teasing apart complex biological processes involved in disease progression like heart failure was like finding a needle in a haystack,’ says study co-senior author Mark Mercola, PhD, professor in the Development, Aging, and Regeneration Program at Sanford-Burnham and professor of Bioengineering at UC San Diego Jacobs School of Engineering. ‘The results of this study validate our approach to identifying microRNAs as potential therapeutic targets with significant clinical value.’
Dr. Mercola’s laboratory has pioneered the use of robotic high-throughput methods of drug discovery to identify new targets for heart failure. According to co-lead study authors Christine Wahlquist and Agustin Rojas Muñoz, PhD, developers of the approach and researchers in Mercola’s lab at Sanford-Burnham, they used high-throughput robotics to sift through the entire genome for microRNAs involved in heart muscle dysfunction.
Subsequently, the researchers at the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai found that injecting a small piece of RNA to inhibit the effects of miR-25 dramatically halted heart failure progression in mice. In addition, it also improved their cardiac function and survival.
‘In this study, we have not only identified one of the key cellular processes leading to heart failure, but have also demonstrated the therapeutic potential of blocking this process,’ says co-lead study author Dongtak Jeong, PhD, a post-doctoral fellow at the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai in the laboratory of the study’s co-senior author Roger J. Hajjar, MD.
Nearly 6 million Americans suffer from heart failure, which is when the heart becomes weak and cannot pump enough blood and oxygen throughout the body. Heart failure is a leading cause of hospitalisation in the elderly. Often, a variety of medications are used to provide heart failure patients temporary relief of their debilitating symptoms. However, these medications do not improve cardiac function or halt the progression of the disease. Mount Sinai Health System

Thermo Fisher Scientific and the Department of Systems Biology at the Technical University of Denmark (DTU) have formed a collaboration to pursue breakthroughs in the understanding of how cellular protein networks drive important diseases. Under the collaboration, Thermo Fisher will provide early access to new technology and designs, and DTU proteomics scientists will provide feedback and collaborate on new applications. The centerpiece of this collaboration is a new proteomics laboratory in Lyngby, Denmark equipped with the latest liquid chromatography- mass spectrometry (LC-MS) technology. This includes the unique Thermo Scientific Orbitrap Fusion Tribrid LC-MS system that offers unprecedented depth of analysis of biological samples. ‘Studying the dynamic rewiring of cellular signaling networks requires state-of-the-art mass spectrometry,” said DTU professor Rune Linding. “The Orbitrap Fusion system enables us to push the boundaries and analyse completely new avenues of cellular decision processes, and perform genome-scale studies of how the dynamics in these networks affect cell behaviour. This is crucial, as it is now clear that the progression of complex diseases such as cancer is due to changes in these molecular networks. We were extremely excited to see, only a few days aft er installation, the Orbitrap Fusion system generate the best MS/MS data we have ever seen for the characterization of phosphorylation sites on critical tumour samples.” DTU is establishing the state-of-the-art laboratory to develop new experiments to dig deeper into the core machinery of the cell.

Before doctors like Matthias Kretzler can begin using the results of molecular research to treat patients, they need science to find an effective way to match genes with the specific cells involved in disease. As Kretzler explains, finding that link would eventually let physicians create far more effective diagnostic tools and treatments.

‘Among many uses, it would allow us to develop cell-type targeted therapies,’ said Kretzler, a University of Michigan professor of internal medicine and computational medicine and bioinformatics. He recently collaborated with Princeton University professor Olga Troyanskaya on a way to match genes to cells. ‘If you identify a [disease] that is in the liver or in the kidney, you could target those areas and not affect other parts of the body,’ he said.

Although scientists have decoded the human genome — the list of all the genes in human cells — they still have great difficulty determining the specific genes that are activated to make a kidney cell as opposed to a liver or heart cell.

In theory, an easy way to link genes to cells would be to isolate a cell and test it. However, solid human tissue is so closely packed that even the finest surgical techniques cannot separate types of cells efficiently enough for analysis. A kidney biopsy, for example, produces a mix of several different types of cells that Kretzler dismisses as ‘kidney soup.’

Princeton University and University of Michigan researchers have developed a system that allows computers to ‘virtually dissect’ a kidney in a way that surgery cannot. The machine uses data from an array of gene-activity measurements in patients’ kidney biopsies to mathematically separate cells and identify genes that are turned on in a specific cell type. The researchers identified 136 genes involved in the creation of a critical kidney cell called a podocyte, tiny cells that serve as filters in the kidneys and are frequently involved in kidney disease.
‘We call it in-silico nano-dissection,’ said Troyanskaya, a professor of computer science and the Lewis-Sigler Institute for Integrative Genomics. Using a large database of such gene-activity measurements to track genetic lineage allows scientists to refine their analysis through thousands of measurements, something that would be impossible with individual cell cultures, she said.

The method has proven far faster and significantly more effective than current techniques. Researchers from Kretzler’s lab at Michigan and Troyanskaya’s at Princeton reported that they had identified 136 genes involved in the creation of a critical kidney cell called a podocyte. In decades of research, only 46 had been previously identified.

‘The potential for this is huge,’ said Behzad Najafian, a University of Washington assistant professor of pathology who specializes in renal pathology. ‘I believe this novel technique, which is a significant improvement in cell lineage-specific gene-expression analysis, will not only help us understand the pathophysiology of kidney diseases better through biopsy studies, but also provides a strong tool for discovery or validation of cell-specific urine or plasma biomarkers.’ Princeton University