In a study published today in the journal EMBO Molecular Medicine1, the team led by Prof. Nicolas Lévy identifies the mechanism associated with the accumulation of progerin, a toxic protein produced in the course of ageing, and demonstrates the therapeutic potential of a new drug – MG132 – to treat progeria, a rare syndrome involving premature and accelerated ageing. Nicolas Lévy and his team have demonstrated the ability of this drug to considerably reduce progerin production and simultaneously degrade it. This drug, along with other compounds from the same family, is undergoing evaluation for the treatment of other rare diseases, as well as more common diseases including certain types of cancer.

This work, supported by Inserm, Aix-Marseille University, the A*Midex foundation and AFM-Téléthon, paves the way to a therapeutic trial and the development of compounds to reduce the effects of accelerated and physiological ageing.

 Hutchinson Gilford progeria syndrome (HGPS) is an extremely rare and severe genetic disease that causes precocious and accelerated ageing in children. Although it spares the brain functions, it progressively leads to ageing in the vast majority of the organs, with particularly dramatic consequences being observed in the skin, adipose tissue, cardiovascular system and bones. Constantly fatal, death usually occurs around the age of 13 years. This disease, which affects 1 birth per 10–20 million worldwide, is caused by a mutation in the LMNA gene taht leads to the production  and  accumulation  of  a toxic protein, progerin, in cells nuclei. Progerin causes serious cellular dysfunctions (defects in DNA breaks repair, failure of cell proliferation    and    differentiation, etc…). Progeria is thus a unique model for understanding major mechanisms involved in natural ageing. Since 2003, Nicolas Lévy and his team have identified the gene and mechanism inducing progeria and other premature ageing diseases, developed therapeutic approaches, and conducted the first European trial in 12 children affected with the disease.

In the study published today, Nicolas Lévy’s team – UMR_S910, Aix-Marseille University/Inserm – has identified the mechanism whereby progerin accumulates without being degraded, and has identified a family of drugs that not only allow a tremendous reduction in its initial production, but also the simultaneous elimination of the remaining produced progerin. This study, using cells from children affected with progeria as well as a mouse model developed within this same team£, paves the way for a clinical trial for  progeria and other severe diseases of accelerated ageing. It will also be exploited in order to define the potential of each drug identified in the family, with respect to rare genetic diseases, cancers and natural ageing. For Dr Karim Harhouri, first author of the study, “These 5 years of work have enabled us to discover the real mechanism whereby progerin accumulates without being degraded, and a class of drugs that had not been exploited before, with a seemingly major therapeutic potential.”

“This work is part of the main thrust of our research in the area of rare genetic diseases, continuously aimed at translating knowledge of fundamental mechanisms into the most efficient possible treatments for our patients. This could not have been achieved without the convergence of talents, human skills and expertises to reach a common ambition, that of expanding effective treatments for our patients while reducing the access time; this is the philosophy we should be adopting, that of integrated research on care-related problems, and which we are upholding with the creation of the GIPTIS Institute*,” explains Nicolas Lévy, principal investigator, senior author of the study and proponent of the GIPTIS Institute*, which should open its doore in Marseille in 2020.

This work is the subject of a joint patent application – WO2016/113357 – holded by Aix- Marseille University, Inserm, AFM-Téléthon, CNRS and the ProGeLife** biotech company.

*GIPTIS : Genetics Institute for Patients, Therapies, Innovation and Science (www.giptis.com)

** www.progelife.com

©F Alpy/IGBMC

Cholesterol plays a central role in many living processes. In a new study, a team led by Catherine-Laure Tomasetto, Inserm research director at the Institute of Genetics and Molecular and Cellular Biology (Inserm/CNRS/Université de Strasbourg) reveals the role played by the STARD3 protein in the distribution of cholesterol within cells. A little like molecular velcro, this protein has the capacity to form membrane contacts between two cell organelles, enabling it to transport cholesterol from one organelle to another.

This research has been published in the EMBO Journal

Cholesterol is a component of biological membranes and essential for human cell functioning. A cell has two ways of obtaining cholesterol: by capturing it in the blood and internalizing it using endosomes, or by producing it in the endoplasmic reticulum, a network covering the inside of the cell that synthesizes most lipids. Once captured or synthesized, cholesterol is redistributed throughout the cell’s membranes via mechanisms that have not all been elucidated.

Since cholesterol is not water-soluble, its movements within the cell are very limited. To ensure its transport, the cells have specialized transporters. Catherine-Laure Tomasetto’s team is interested in one of them, protein STARD3, the role of which had remained quite a mystery until now. In this new study, the researchers unraveled some of that mystery. STARD3 is anchored to the endosomes, cell organelles that ensure communication between the outside and the inside of cells. Within the cell, STARD3 attaches to VAP, a protein that is itself fixed to the endoplasmic reticulum. This association creates close appositions between the endosome and the endoplasmic reticulum that are known as membrane contact sites. At these sites, the membranes of the two organelles are very close (less than 30 nm), thus facilitating communication and exchange. In this study, the researchers demonstrated that these membrane contact sites between the endosomes and the endoplasmic reticulum form a type of bridge, enabling STARD3 to transfer cholesterol from the membrane of the endoplasmic reticulum to that of the endosome, thereby rerouting some of the cholesterol that was intended for the plasma membrane.

These results therefore identify a new pathway that regulates cholesterol flow within cells. Understanding how cells balance the two available cholesterol sources will probably help us better understand the mechanisms of certain neurodegenerative or cardiovascular disorders presenting alterations in cholesterol distribution.

This study was funded by the French National Cancer Institute (INCA), the French foundation for medical research (FRM), the French League against cancer, the Ara Parseghian Medical Research Foundation, and the Vaincre les Maladies Lysosomales (overcoming lysosomal diseases) association.

The formation of a membrane contact site for the transport of cholesterol

Image credit: F Alpy/IGBMC

A team of researchers in France, led by Dr. Ana Buj-Bello (Genethon/Inserm) and teams at the University of Washington and Harvard Medical School in the United States, achieved a new step towards the treatment of myotubular myopathy by gene therapy. The researchers demonstrated the efficacy of administration of a therapeutic vector by a single intravenous injection and identified the dose that restores long-term muscular strength in a large animal model of the disease.

This work, published today in Molecular Therapy, has been achieved thanks to donations from the French Telethon and the support of the Myotubular Trust.
Myotubular myopathy is an X-linked genetic disease affecting 1 in 50,000 newborn boys. It is caused by mutations in the MTM1 gene encoding myotubularin, a protein involved in the functioning of muscle cells. The severe form of the disease leads to hypotonia, generalized muscle weakness and death in early infancy due to breathing difficulties. Dogs naturally affected by this myopathy also have a reduced life expectancy. To date, there is no effective treatment for this rare disease.

In the present study, Genethon’s team developed and manufactured an adeno-associated virus (AAV) vector able to deliver a normal copy of the MTM1 gene in the entire musculature. The AAV product was administrated by a simple intravenous injection in ten week-old dogs manifesting the first symptoms of the disease – instead of the locoregional route of administration used in previous studies (Science Translational Medicine, January 2014).

The treatment restored whole-body muscle strength and function, and prolonged the life of affected dogs. Treated dogs were indistinguishable from normal animals 9 months after product injection.

Dr. Ana Buj-Bello, Genethon/Inserm said: « We report a dose-finding study and show the therapeutic benefit of the vector by a single intravenous injection. It is a clinically-relevant route of administration and represents a step towards a clinical trial in patients”.

© Fabrice Hyber, pour Organoïde/Institut Pasteur

French researchers have identified a marker that makes it possible to differentiate “dormant” HIV-infected cells from healthy cells. This discovery will make it possible to isolate and analyze reservoir cells which, by silently hosting the virus, are responsible for its persistence even among patients receiving antiviral treatment, whose viral load is undetectable. It offers new therapeutic strategies for targeting infected cells. This research is part of the ANRS strategic program “Réservoirs du VIH”. It is the result of a collaboration between the CNRS, Montpellier University, Inserm, the Institut Pasteur, the Henri-Mondor AP-HP hospital in Créteil, the Gui de Chauliac hospital (CHU de Montpellier) and the VRI (Vaccine Research Institute), and is published in the journal Nature on March 15, 2017. A patent owned by the CNRS has been filed for the diagnostic and therapeutic use of the identified marker.

Since 1996, there has been consensus among the scientific community that a cure for HIV will involve targeting “reservoir cells” that host the virus in the organisms of patients undergoing triple therapy. HIV can remain hidden in these reservoirs, in latent form, for several decades, eluding the immune system’s response and antiviral treatments, without any viral protein being expressed. But if treatment ceases, the virus massively proliferates and the disease progresses again. Patients must therefore receive treatment for life. To envisage eliminating this dormant virus, a first stage consists in distinguishing the HIV-infected reservoir cells from their healthy counterpart cells, which resemble them to a very large degree. This is what has been achieved by a team of researchers, who have identified a marker of reservoir cells: a protein present only on the surface of infected cells.

Hypothesizing that HIV might leave a mark on the surface of its host cell, researchers from the Institut de génétique humaine (CNRS/Montpellier University) first worked in vitro on an infection model developed in their laboratory. After comparing infected cells and healthy cells,[1] they noticed one particular protein, coded by a gene among the hundred of those expressed in a specific way by infected cells. Present only on the surface of the infected cells, the CD32a protein thus met, in vitro, the criteria of a reservoir cell marker. This was then confirmed by experiments on clinical samples. By studying blood samples from 12 patients living with HIV and receiving treatment,[2] the researchers isolated the cells expressing the marker and observed that almost all were HIV carriers. In vitro, the activation of these cells induced a production of viruses capable of reinfecting healthy cells whereas their elimination entailed a significant delay in viral production.

In the fight against HIV, this discovery paves the way to a better fundamental understanding of viral reservoirs, which it will now be possible to isolate more easily and analyze directly. In the longer term, it should lead to therapeutic strategies aiming to eliminate the latent virus from the organism and make remission—at least temporary—possible in the absence of antiviral treatments.

This research received support from the ANRS, MSD Avenir, the European Commission, the Fondation Bettencourt Schuelle, the Fondation pour la recherche médicale and the Vaccine Research Institute (VRI).

[1] The cells studied are T CD4 lymphocytes, whose numbers are progressively reduced upon infection by HIV. The number of these cells is thus used by doctors to monitor the progression of the disease and the efficacy of treatments.

[2] Patients monitored by the Clinical Immunology and Infectious Disease Department at the Henri-Mondor AP-HP hospital in Créteil and by the Infectious and Tropical Disease Department at Gui de Chauliac hospital (CHU de Montpellier).

On 13 June last, the Inserm Ethics Committee assembled over a hundred individuals at its annual seminar. All those present had the benefit of an ethical perspective on many problems posed by biomedical research. One of the questions addressed was that of CRISPR-Cas9 technology. The Ethics Committee has devoted a specific opinion to it, while the NIH has just obtained a first green light for a human cancer immunotherapy trial.

The Inserm Ethics Committee (CEI) may receive referrals or carry out investigations on its own initiative to reflect on ethical questions raised by medical science- and health-related research carried out within the Institute. At the end of its reflection, it issues an opinion in the form of notes that may evolve as new contributions are added. In 2015, the CEO of Inserm requested the Ethics Committee to specifically examine questions related to the development of CRISPR technology, and particularly:

1- What are the questions raised by the technology as such?

2- Does the rapidity of its development raise particular problems?

3- Does the simplicity of its use call for regulation of its implementation in the laboratory?

Given the technical advantages of the method, and its very rapid dissemination, the question now is to evaluate where, when and how its use might pose an ethical problem. It seemed immediately important to distinguish three areas associated with different issues:

1/ application of the technology to humans, which essentially raises the question of germ line modifications;

2/ application to animals, particularly “pest” species, which raises the question of potential horizontal gene transfer and the emergence of irreversible damage to biodiversity;

3/ risks of damage to the environment.

Recommendations of the Inserm Ethics Committee

The Committee immediately proposes that Inserm adopt the following principles:

1- To encourage research aimed at evaluating the efficacy and safety of CRISPR technology and other recently published genome editing technologies, in experimental models that can allow case-by-case determination of the benefit/risk balance of a therapeutic application, including any applications that involve germ cells and the embryo. This information is essential to the future determination of what might be authorised for human use in terms of therapeutic approaches.

2- The potentially adverse effects of gene drive systems must be evaluated before any use outside of a laboratory, observing the containment rules already in force for other genetic modifications. Evaluations must be made over long periods, given the transmissible nature of the driver gene. Reversibility measurements should be provided for in the event of escape or adverse effects. Such analyses and the design of multiple scenarios require the constitution of pluridisciplinary teams.

3- To comply with the prohibition of any modification of the germ line nuclear genome for reproductive purposes in the human species, and not support any application to modify the legal conditions until uncertainties about the risks have been clearly evaluated, and until a broad consultation involving multiple partners from civil society has ruled on this scenario.

4- To participate in any national or international initiative dealing with questions of freedom of research and medical ethics, including initiatives with emerging countries that will also be affected by the development of genome editing technologies.

5- Finally, to draw attention to the more philosophical question which contrasts the plasticity of life with the idea of a human nature founded on the only biological constant. Awareness needs to be increased regarding the utopia and dystopias that can be generated by some therapeutic promises.