Lesch-Nyan gets nucleo-tide: too musch folate in culture has simply hidden the understanding beneath

Lesch-Nyhan is a rare genetic neurological disease, affecting 1 in 380,000 newborns. Patients suffer from overproduction of uric acid, anemia, severe neurological problems, and compulsive self-injurious behavior. The pathology is caused by a deficiency of HGPRT, an enzyme that participates in the metabolism of purine nucleotides. Purines regulate many biological processes and are part of the basic structure of DNA and RNA. They can be synthesized in two different metabolic pathways: the de novo synthesis, from simple precursors, such as amino acids and folic acid derivatives; and the salvage pathway, a recycling system where HGPRT participates, in which the cell saves energy. A HGprt deficiency causes the acceleration of the de novo synthesis pathway to try to compensate the system. An international study by the Institute of Neuroscience of the UAB (INC-UAB), Emory University and Hospital Universitario La Paz, shows that patients suffering from Lesch-Nyhan present biochemical alterations in skin cells (fibroblasts), urine and cerebrospinal fluid.

Researchers have also discovered why these alterations had not been observed before: the high levels of folic acid (B9 vitamin) usually used in cell cultures reverse them. This is a key discovery to advance in the research of this disease and its treatment, which may also have implications in the research of other pathologies, especially in those in which nucleotide metabolism is affected. Since measuring the nucleotide concentration in the brain of a living patient is not feasible, scientists often use cell cultures. However, the studies conducted until now in Lesch-Nyhan patients’ cultured cells have never revealed any abnormalities in their nucleotide content. In this work, led by José Manuel López from the INC-UAB, in collaboration with Emory University in Atlanta, and the Hospital Universitario La Paz in Madrid, the researchers show that these alterations could not be detected because, in most laboratories, cells are maintained in mediums that have extremely higher levels of folic acid than physiological concentrations.

In this study researchers used physiological levels of folic acid in their culture mediums and observed two important alterations in patients’ fibroblasts. Firstly, an accumulation of imidazole-carboxamide ribotide or ZMP, an intermediate product in the de novo nucleotide synthesis that is potentially toxic; and secondly, a reduction in ATP, the most abundant purine nucleotide in cells, which is essential for cellular energy. Researchers also found ZMP derivatives increased in the urine and cerebrospinal fluid of patients, concluding that the alterations detected in fibroblasts can also occur in the brain and in other tissues. Culture mediums usually have 100 times more folic acid than the levels found in blood. This is for cells to divide and grow faster in a culture plate, but it does not reproduce what happens in the body. They therefore engineered cell culture conditions that allow for the study of the mechanisms involved in the development of this disease.

Data from their study also suggests a possible treatment, since the alterations observed in the cultures are reversed with high levels of folic acid. According to the researchers, the research may have highly relevant consequences, since manipulating folic acid levels can be a valuable strategy to study the pathogenesis of this rare disease, for which there is no known treatment. The discovery could also have implications in the research of other diseases in which high concentrations of folic acid in the culture medium could be masking cellular alterations, such as those in which nucleotide metabolism is affected.

  • edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry

Scientific references

López JM et al. Proc Acad Natl Sci USA 2020 June; 117(22):12071-79.

Ruillier V, Tournois J et al. JCI Insight. 2020 Feb 27; 5(4):e132094.

Momosaki K, Kido J et al. Case Rep Neurol. 2019 Sep 19;11(3):256-264.

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Informazioni su Dott. Gianfrancesco Cormaci 2450 Articoli
- Laurea in Medicina e Chirurgia nel 1998 (MD Degree in 1998) - Specialista in Biochimica Clinica nel 2002 (Clinical Biochemistry specialty in 2002) - Dottorato in Neurobiologia nel 2006 (Neurobiology PhD in 2006) - Ha soggiornato negli Stati Uniti, Baltimora (MD) come ricercatore alle dipendenze del National Institute on Drug Abuse (NIDA/NIH) e poi alla Johns Hopkins University, dal 2004 al 2008. - Dal 2009 si occupa di Medicina personalizzata. - Detentore di un brevetto sulla preparazione di prodotti gluten-free a partire da regolare farina di frumento immunologicamente neutralizzata (owner of a patent concerning the production of bakery gluten-free products, starting from regular wheat flour). - Responsabile del reparto Ricerca e Sviluppo per la società CoFood s.r.l. (leader of the R&D for the partnership CoFood s.r.l.) - Autore di un libro riguardante la salute e l'alimentazione, con approfondimenti su come questa condizioni tutti i sistemi corporei. - Autore di articoli su informazione medica, salute e benessere sui siti web salutesicilia.com e medicomunicare.it
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