Scientists have established a genetic mouse model for primary ovarian insufficiency (POI), a human condition in which women experience irregular menstrual cycles and reduced fertility, and early exposure to oestrogen deficiency.
POI affects approximately one in a hundred women. In most cases of primary ovarian insufficiency, the cause is mysterious, although genetics is known to play a causative role. There are no treatments designed to help preserve fertility. Some women with POI retain some ovarian function and a fraction (5-10 percent) have children after receiving the diagnosis.
Having a mouse model could accelerate research on the causes and mechanisms of POI, and could eventually lead to treatments, says Peng Jin, PhD, associate professor of human genetics at Emory University School of Medicine.
The paper was the result of a collaboration between researchers at Emory and the Institute of Zoology, Chinese Academy of Sciences in Beijing. Dahua Chen, PhD, associate director of the State Key Laboratory of Reproductive Biology, is the senior author and postdoctoral fellow Cuiling Lu is the first author. Stephanie Sherman, PhD, professor of human genetics at Emory, is a co-author.
The mouse model builds on research on women who are carriers of a ‘premutation’ for fragile X syndrome, a leading cause of inherited intellectual disability.
The mice have a fragment of a human X chromosome from a fragile X premutation carrier. Other non-genetic mouse models used to study menopause include surgical removal of the ovaries, or exposure of mice to a chemical, 4-vinylcyclohexene diepoxide, which depletes the ovaries.
‘While the fragile X premutation is a leading cause of POI, I think this model will be useful and relevant for all women with this condition,’ Jin says.
Women with the fragile X premutation account for around two percent of spontaneous POI cases and 14 percent of familial POI cases. About 20 percent of women who carry the fragile X premutation experience POI, the disorder now called fragile X-associated POI, or FXPOI.
Fragile X syndrome is caused by the expansion of a ‘triplet repeat’ in a gene (FMR1) that is important for signalling in the brain. In fragile X syndrome, the triplet repeat — three DNA letters (CGG) repeated many times — forces the gene to shut off.
For a woman who carries the premutation, the triplet repeat is not large enough to shut the gene off. There is a risk that it will expand in her children enough to generate fragile X syndrome. In addition, the triplet repeat appears to have an effect on the woman’s ovaries, independently from its influence on the FMR1 gene.
Jin says studying mice that have an analogous genetic alteration will help scientists understand what’s happening to the ovaries in POI. It appears that the RNA coming from the premutation impairs development of the ovarian follicles, the structures in which eggs/oocytes mature.
The research team found that a quarter of premutation-carrying female mice are infertile. When they are housed with male mice, those that do have pups have them a month later on average (12.5 weeks of age compared to 8.5 weeks), and they have fewer pups.
Puberty occurs at roughly five weeks of age in mice, and the premutation mice have alterations in their ovaries already before puberty. At 25 days of age, there are a reduced number of mature follicles in ovaries of the female mice carrying the premutation. Those mice also have altered levels of hormones resembling those of women with POI, such as elevated FSH (follicle stimulating hormone).
The research team found that in the ovaries of mice with the fragile X premutation, ovulation-related genes are less active. In addition, two cellular signalling pathways (Akt/mTOR) are less active in the ovaries, suggesting that drugs that affect those pathways could be used to treat POI. Emory University

A current focus in global health research is to make medical tests that are not just cheap, but virtually free. One such strategy is to start with paper – one of humanity’s oldest technologies – and build a device like a home-based pregnancy test that might work for malaria, diabetes or other diseases.
A University of Washington bioengineer recently developed a way to make regular paper stick to medically interesting molecules. The work produced a chemical trick to make paper-based diagnostics using plain paper, the kind found at office supply stores around the world.
‘We wanted to go for the simplest, cheapest starting material, and give it more capability,’ said Daniel Ratner, a UW assistant professor of bioengineering and lead author of the paper
‘We also wanted to make the system as independent of the end applications as possible, something any researcher could plug into.’
Many paper-based diagnostics are made from nitrocellulose, a sticky membrane used in pregnancy tests and by medical researchers to detect proteins, DNA or antibodies in the human immune system.
Ratner hopes to replace that specialised membrane with cheap, ubiquitous paper, and to use it for any type of medical test – not just the big, biological molecules.
The UW technique uses minimal equipment or know-how. The researchers used a cheap, industrial solvent called divinyl sulfone that can be bought by the gallon and has been used for decades as an adhesive. Ratner’s group discovered they could dilute the chemical in water, carefully control the acidity, then pour it into a Ziploc bag and add a stack of paper, shake for a couple of hours, and finally rinse the paper and let it dry.
The dried paper feels smooth to the touch but is sticky to all kinds of chemicals that could be of medical interest: proteins, antibodies and DNA, for example, as well as sugars and the small-molecule drugs used to treat most medical conditions.
‘We want to develop something to not just ask a single question but ask many personal health questions,’ Ratner said. ‘‘Is there protein in the urine? Is this person diabetic? Do they have malaria or influenza?’’
To test their idea, the researchers ran the treated paper through an inkjet printer where the cartridge ink had been replaced with biomolecules, in this case a small sugar called galactose that attaches to human cells. They printed the biomolecules onto the sticky paper in an invisible pattern. Exposing that paper to fluorescent ricin, a poison that sticks to galactose, showed that the poison was present.
Now that they have proven their concept, Ratner said, they hope other groups will use the paper to develop actual diagnostic tests. University of Washington

Researchers from Inserm and the Université Lille/Université Lille Nord de France have recently used a neurodegeneration model of Alzheimer’s disease to provide experimental evidence of the relationship between obesity and disorders linked to the tau protein. This research was conducted on mice and it corroborates the theory that metabolic anomalies contribute massively to the development of dementia.
In France, more than 860,000 people suffer from Alzheimer’s disease and related disorders, making them the largest cause of age-related loss of intellectual function. Cognitive impairments observed in Alzheimer’s disease result from the accumulation of abnormal tau proteins in nerve cells undergoing degeneration. We know that obesity, a major risk factor in the development of insulin resistance and type 2 diabetes, increases the risk of dementia during the ageing process. However, the effects of obesity on ‘Taupathies’ (i.e. tau protein-related disorders), including Alzheimer’s disease, were not clearly understood. In particular, researchers assumed that insulin resistance played a major role in terms of the effects of obesity.
The ‘Alzheimer & Tauopathies’ team from mixed research unit 837 (Inserm/Université Lille 2/Université Lille Nord de France) directed by Dr. Luc Buée, in collaboration with mixed research unit 1011 ‘Nuclear receptors, cardiovascular diseases and diabetes’, have just demonstrated, in mice, that obese subjects develop aggravated disorders. To achieve this result, young transgenic mice, who develop tau-related neurodegeneration progressively with age, were put on a high-fat diet for five months, leading to progressive obesity.
　
‘At the end of this diet, the obese mice had developed an aggravated disorder both from the point of view of memory and modifications to the Tau protein’ explains David Blum, in charge of research at Inserm.
This study uses a neurodenegeneration model of Alzheimer’s disease to provide experimental evidence of the relationship between obesity and disorders linked to the tau protein. Furthermore, it indicates that insulin resistance is not the aggravating factor, as was suggested in previous studies.
‘Our research supports the theory that environmental factors contribute massively to the development of this neurodegenerative disorder’ underlines the researcher. ‘Our work is now focussing on identifying the factors responsible for this aggravation’ he adds. Inserm

A new study finds significant associations between antibodies for multiple oral bacteria and the risk of pancreatic cancer, adding support for the emerging idea that the ostensibly distant medical conditions are related.
The study of blood samples from more than 800 European adults found that high antibody levels for one of the more infectious periodontal bacterium strains of Porphyromonas gingivalis were associated with a two-fold risk for pancreatic cancer. Meanwhile, study subjects with high levels of antibodies for some kinds of harmless ‘commensal’ oral bacteria were associated with a 45-percent lower risk of pancreatic cancer.
‘The relative increase in risk from smoking is not much bigger than two,’ said Brown University epidemiologist Dominique Michaud, the paper’s corresponding author. ‘If this is a real effect size of two, then potential impact of this finding is really significant.’
Pancreatic cancer, which is difficult to detect and kills most patients within six months of diagnosis, is responsible for 40,000 deaths a year in the United States.
Several researchers, including Michaud, have found previous links between periodontal disease and pancreatic cancer. The paper is the first study to test whether antibodies for oral bacteria are indicators of pancreatic cancer risk and the first study to associate the immune response to commensal bacteria with pancreatic cancer risk. The physiological mechanism linking oral bacteria and pancreatic cancer remains unknown, but the study strengthens the suggestion that there is one.
‘This is not an established risk factor,’ said Michaud, who is also co-lead author with Jacques Izard, of the Forsyth Institute and Harvard University. ‘But I feel more confident that there is something going on. It’s something we need to understand better.’
Izard, a microbiologist, said the importance of bacteria in cancer is growing. ‘The impact of immune defence against both commensals and pathogenic bacteria undeniably plays a role,’ he said. ‘We need to further investigate the importance of bacteria in pancreatic cancer beyond the associated risk.’
To conduct their research, Michaud and Izard drew on medical records and preserved blood samples collected by the Imperial College-led European Prospective Investigation into Cancer and Nutrition Study, a massive dataset of more than 500,000 adults in 10 countries. Detailed health histories and blood samples are available from more than 380,000 of the participants.
From that population, the researchers found 405 people who developed pancreatic cancer, but no other cancer, and who had blood samples available. The researchers also selected 416 demographically similar people who did not develop pancreatic cancer for comparison.
The researchers blinded themselves to which samples came from cancer patients and which didn’t during their analysis of the blood, which consisted of measuring antibody concentrations for 25 pathogenic and commensal oral bacteria. In their study design and analysis they controlled for smoking, diabetes, body mass index, and other risk factors.
An important element of the study design was that date of the blood samples preceded the diagnosis of pancreatic cancer by as much as a decade, meaning that the significant difference in antibody levels were likely not a result of cancer.
Instead, the underlying mechanisms that link Porphyromonas gingivalis to pancreatic cancer could be causal, Michaud said, although much more research is needed to understand this association.
Meanwhile, the researchers speculate, the association of high levels of antibodies for commensal bacteria and pancreatic cancer, may indicate an innate, highly active immune response that is protective against cancer. Brown University

Two studies led by investigators at Weill Cornell Medical College shed light on the molecular biology of three blood disorders, leading to novel strategies to treat these diseases.
The two new studies propose two new treatments for beta-thalassaemia, a blood disorder which affects thousands of people globally every year. In addition, they suggest a new strategy to treat thousands of Caucasians of Northern European ancestry diagnosed with HFE-related hemochromatosis and a novel approach to the treatment of the rare blood disorder polycythaemia vera.
These research insights were only possible because two teams that included 24 investigators at six American and European institutions decoded the body’s exquisite regulation of iron, as well as its factory-like production of red blood cells.
‘When you tease apart the mechanisms leading to these serious disorders, you find elegant ways to manipulate the system,’ says Dr. Stefano Rivella, associate professor of genetic medicine in pediatrics at Weill Cornell Medical College.
For example, Dr. Rivella says, two different gene mutations lead to different outcomes. In beta-thalassemia, patients suffer from anaemia — the lack of healthy red blood cells — and, as a consequence, iron overload. In HFE-related haemochromatosis, patients suffer of iron overload. However, he adds, one treatment strategy that regulates the body’s use of iron may work for both disorders.
Additionally, investigators found another strategy, based on manipulating red blood cell production, could also potentially treat beta-thalassaemia as well as a very different disorder, polycythaemia vera.
Dr. Rivella and his colleagues tackled erythropoiesis — the process by which red blood cells (erythrocytes) are produced — as a way to decipher and decode the two blood disorders beta-thalassaemia and polycythaemia vera.
Beta-thalassaemia, a group of inherited blood disorders, is caused by a defect in the beta globin gene. This results in production of red blood cells that have too much iron, which can be toxic, resulting in the death of many of the blood cells. What are left are too few blood cells, which leads to anaemia. At the same time, the excess iron from destroyed blood cells builds up in the body, leading to organ damage. In polycythaemia vera, a patient’s bone marrow makes too many red blood cells due to a genetic mutation that doesn’t shut down erythropoiesis — the production of the cells.
The researchers studied both normal erythropoiesis, in which a person makes enough red blood cells to replace those that are old, and a mechanism called stress erythropoiesis, which flips on when a person requires extra blood cells — such as loss of blood from an accident. The hormone erythropoietin (EPO) controls red blood cell production, and can also induce stress erythropoiesis. Iron is also essential, says Dr. Rivella. ‘The two well-known elements needed to switch between normal and stress erythropoiesis are EPO and iron,’ he says.
But Dr. Rivella and his team found that a third player is essential: macrophages, the immune cells that engulf cellular garbage and pathogens. Macrophages had been known to digest the iron left when old blood cells are targeted for destruction, but Dr. Rivella discovered that they also are necessary for stress erythropoiesis. He found macrophages need to physically touch erythroblasts, the factories that make red blood cells, in order for more factories to be created so that they can churn out red blood cells.
‘No one knew macrophages were a part of emergency red blood cell production. We now know they provide fuel to push red blood cell factories to work faster,’ says the study’s lead author Dr. Pedro Ramos, a former postdoctoral researcher at Weill Cornell.
The research team then looked at diseases in which there are too many red blood cell factories. Polycythemia vera was one of the conditions examined. The researchers disabled macrophage functioning in mice with polycythemia vera and found that red blood cell production returned to normal.
In beta-thalassemia, the body increases the number of red blood cell factories to make up for the lack of viable blood cells — a strategy that doesn’t work. As a result, patients develop enlarged spleens and livers due to the overload of erythroblasts in those organs.
The researchers found in mouse models that if they suppress the function of macrophages, the number of blood cell factories revert back to normal levels. However, there was also an additional benefit discovered. One of the functions of macrophages is to put excess recycled iron into erythroblasts. Researchers report if you suppress that function, less iron goes into the red blood cells. ‘So you then make red blood cells that have less iron, and they are now closer in structure to what they should be,’ says Dr. Rivella.
In animal studies, the researchers saw that decoupling macrophages from the erythroblasts not only reduced the number of blood cell factories, but also improved anaemia.
The discovery could be translated into an experimental therapy by finding the molecule that physically binds a macrophage to an erythroblast, and then targeting and inhibiting it. ‘We need macrophages for good health, but it may be possible to decouple the macrophages that contribute to blood disorders,’ Dr. Rivella says. ‘I estimate that up 30 to 40 percent of the beta-thalassaemia population could benefit from this treatment strategy.’
Dr. Rivella also made another connection. He says polycythaemia vera ‘is sort of a tumour of the red cells, because you make too many of them.’ And he notes that previous research on macrophages found that they are very important in cancer metastasis. ‘I see a parallel between the activity of macrophages in supporting the proliferation of cells that are under stress conditions — growing tumors and red blood cells that need to grow,’ he says. ‘It seems to us that macrophages are important in supporting a switch between normal growth and increased growth.’ Weill Cornell Medical College