PAF Grant Maclean

PAF Awards $50,000 New Research Grant

Ken Maclean, PhD, University of Colorado Denver

“Chemical Chaperone Treatment to Restore Enzyme Activity in Folding Mutations of Propionyl-Co-A Carboxylase: Towards a Personalized Therapeutic Strategy in Propionic Acidemia (PA)” – In Summer 2020, PAF awarded a $50,000 grant.”

Propionic acidemia (PA) is a severe life-threatening disease for which there is currently no truly effective treatment. The disease is caused by mutation in one of the two genes that code for the enzyme propionyl-CoA carboxylase (PCC). This enzyme is made up of two different proteins that fold around each other into a complex structure with six of each of these two molecules. This is a very unusual and complex structure for a metabolic enzyme and recent work in our laboratory has found that a number of specific mutations that cause PA cause problems by interfering with the protein folding and/or assembly process leading to a non-functional enzyme and thus the disease. In cells, proteins with complicated folding patterns are often assisted in their folding by other proteins called chaperones. We have observed that a number of mutant forms of PCC can be restored to normal activity if they are helped to fold correctly using these chaperone proteins. In our study, we will examine a number of chemicals that can also function as chaperones and assist with protein folding with a view towards restoring full activity in mutant forms of PCC. This work will initially occur in a bacterial PCC expression system to identify promising compounds and then depending upon progress, move into treating human PCC patient derived cells. These studies have the potential to serve as an initial first step in the rational design of a personalized medicine strategy for patients with specific mutations causing PA.

PAF research summary Elango

PAF Awards $44,253 New Research Grant

Rajavel Elango, PhD, University of British Columbia

“Optimizing amino acids in medical foods to manage propionic acidemia”

Propionic Acidemia (PA) is primarily caused by an enzymatic defect, propionyl-CoA carboxylase (PCC), in the catabolic pathway of valine, isoleucine and other propiogenic precursors. The dietary management of PA mainly depends on protein restriction from food to reduce supply of propiogenic amino acids, and the use of special medical foods. These medical foods contain all essential amino acids and nutrients, but no propiogenic compounds. Recently, concerns have been raised about their use, due to the imbalanced content of the Branched Chain Amino Acids (BCAA) – high leucine, to minimal or no valine and isoleucine. The imbalanced mixture of BCAA negatively impacts plasma concentrations of valine and isoleucine, and has been proposed to affect growth in pediatric PA patients.

In an ongoing retrospective natural history study (n=4), patients with PA treated at our center from birth (or diagnosis) to age 18y, we observed that higher intake of medical food (compared to intact protein) results in lower ht-for-age Z scores. Based on these pilot data, we propose that there is an immediate need to determine the optimal amounts of leucine to be present in the medical foods.

Therefore, the specific objectives of the current study are to:

Stable isotope studies
1. Determine the ideal ratio among BCAA in children using the stable isotope-based indicator amino acid method to optimize protein synthesis in a Proof-of-Principle approach.
2. Test the ratio among BCAA using the same stable isotope-based method in our cohort of PA patients to determine impact on protein synthesis, and plasma metabolite responses.
Determine the impact of the use of natural (intact) vs formula (medical food) protein on anthropometric, biochemical and clinical outcomes via a retrospective natural history study of PA patients treated at BC Children’s Hospital.

Recent dietary guidelines for PA are discouraging the reliance on medical foods as a sole dietary source. However most individuals with PA are at risk for malnutrition and depend on these medical foods as an easy tolerable source of energy and protein. Thus, determining the optimal ratio of BCAA in PA medical foods is necessary to optimize protein synthesis, promote anabolism, growth and prevent the accumulation of toxic metabolites.

Our laboratory, equipped with use of novel stable isotope tracers to examine protein and amino acid metabolism, is ideally suited to address the question of the ideal BCAA ratio to be used for dietary management of PA and potentially impact health outcomes.

PAF attends 2019 Abbott Nutrition Conference

17th Abbott Metabolic Conference: Advances in Management of Inherited Metabolic Disorders
Memphis, TN May 30-June 1, 2019
By Brittany S Smith, PAF Board Member & Treasurer

PAF had a table at the 2019 ABBOTT Metabolic Conference.

There were several presentations and debates that were relevant to the PA community. The first was Dr. Sufin Yap, MD, from Sheffield, UK, who spoke on Organic Acidemias. She described how she has observed her patients in a metabolic crisis and that their livers can enlarge very rapidly. Dr. Yap also described how she has used Carbaglu within a crisis situation and it has brought the ammonia levels down on her patients. The medication was also shown to improve the quality of life of patients with PA using the medication, this was shown by using the PedsQL, a quality of life survey tool. Carbaglu has been used in Europe for over 15 years.

Three dietitians gave a joint presentation on Emergency Preparedness, detailing the impacts of natural disasters on the clinics and staff and also families serviced by their clinics. Amy Cunningham, RD; Suzanne Hollander, RD; and Heather Saavedra, RD, each detailed natural disasters they have had in their areas of the country, which have included wild fires, hurricanes, flooding, droughts, and earthquakes. They have not only impacted families, but the clinic operations. In some cases the hospital and clinics were closed for months. Families, too, were significantly impacted and in one case, a family utilizing one of the clinics had only 5-10 minutes to flee their home. Overall, they indicated a need for all of the metabolic clinics and newborn screening offices to create Emergency Preparedness plans, as well as, helping affected families to prepare as well.

The last session that I wanted to mention was a debate session in which a team of doctors and dietitians each had to debate one side of a treatment suggestion. One was on liver transplantation and whether to encourage or discourage a metabolic family to investigate liver transplantation. While the debate was interesting, the discussion that followed was poignant; they were open to being corrected if they had misstated facts, one being using the livers from those with PA and UCDs in a “domino” transplant, and the other was that they all recommended encouraging their families to seek out information and go down a treatment route if the parents felt that was what was best.

The Propionic Acidemia Nutrition Guidelines are now published

Great News – The “Propionic Acidemia Nutrition Guidelines” Are Now Published!

The Nutrition Guideline Committee is happy to announce that the Organic Acidemia Workgroup has published the “Propionic Acidemia (PROP) Nutrition Guidelines” in the February, 2019 issue of Molecular Genetics and Metabolism. The article is available and can be downloaded at no cost at https://doi.org/10.1016/j.ymgme.2019.02.007.

Publication of the PROP/PA Nutrition Guidelines in Molecular Genetics and Metabolism brings the latest evidence- and consensus-based nutrition management recommendations to the attention of clinicians, researchers, policy makers, insurers, and patients.

The new Nutrition Management Guidelines for PROP/PA provide:

New directions including:
- A greater emphasis on nutritional needs such as nutrient intake, nutritional interventions, supplementation, etc.
- Less emphasis on medical management which has been covered in previous publications;
- Additional topics such as monitoring to ensure nutritional adequacy, nutritional issues with pregnancy and lactation, nutritional management for secondary complications such as pancreatitis, and finally a section addressing liver transplantation and the nutritional management before, during, and after the procedure.

Two consumer-oriented pieces, Frequently Asked Questions and a Consumer Summary, provide patients and families with information to use when interacting with their providers. The summary highlights key recommendations and suggests questions that patients and families may want to discuss with the metabolic team.

When patients and health care providers (HCPs) have the same information, they can work together as a team to identify the treatment that is best for the patient’s situation.
You can access these pieces at the Genetic Metabolic Dietitians International (GMDI) or Southeast Genetics Network websites located at http://www.Southeastgeneticsnetwork.org/ngp and http://www.GMDI.org
The new guidelines should lead to greater consistency of care across centers.
- There are several important resources included in the guidelines including recommended nutrient intakes, monitoring schedules, and nutritional interventions tables.
- A web site that provides all the resources and references used to develop the guidelines is available so that health care clinicians and others can readily obtain the background information related to the guidelines at the websites listed above.
- The guidelines development method utilized evidence from published research, practice-based medical literature and expert consensus processes.

SIMD 2019

PAF at SIMD 2019

Jill Chertow and Maria L. Cotrina represented PAF and the PA Community at the Society for Inherited Metabolic Disorders (SIMD) 41st Annual Meeting on April 6-9, 2019 in Bellevue, Washington. Propionic Acidemia Foundation (PAF) partners with the National Urea Cycle Disorders Foundation (NUCDF) in sharing an exhbition booth.

Maria L. Cotrina shared her poster on “High Incidence of Autism/ASD in Propionic Acidemia: Data from the Propionic Acidemia and Urea Cycle Disorders Registries.”

Arianna F. Anzmann, MS was the recipient of the SIMD Founders Award (Best Oral Presentation by a Trainee). Her presentation “Multi-Omics Studies in Patient-Derived and CRISPR-Edited Cellular Models of Methylmalonc Acidemia and Propionic Acidemia Reveal Dysregulation fo Serine Metabolism: New Directions for Cellular Pathogenesis in Disorders of Branch Chain Amino Acid Metabolism.” was a result of a 2017 PAF awarded grant to Hilary Vernon, MD, PhD, Johns Hopkins University for the project “Targeting Serine and Thiol Metabolism in Propionic Acidemia”.

Propionic Acidemia Foundation Research Grant – Richard

PAF Awards $33,082.12 Research Grant in 2019

PAF Awards $30,591 Continuation Grant in 2020

Eva Richard, PhD, Universidad Autonoma de Madrid, Spain

“Cardiomyocytes derived from induced pluripotent stem cells as a new model for therapy development in propionic acidemia”

Understanding the cellular and molecular mechanisms that occur in genetic diseases is essential for the investigation of new strategies for their prevention and treatment. In this context, induced pluripotent stem cells (iPSC) offer unprecedented opportunities for modeling human disease. One of the fundamental powers of iPSC technology lies in the competency of these cells to be directed to become any cell type in the body, thus allowing researchers to examine disease mechanisms and identify and test novel therapeutics in relevant cell types.

The main objective of this project is focused on the generation of human iPSC-derived cardiomyocytes (hiPSC-CMs) from propionic acidemia (PA) patients as a new human cellular model for the disease.In PA, cardiac symptoms, namely cardiac dysfunction and arrhythmias, have been recognized as progressive late-onset complications resulting in one of the major causes of disease mortality. Using hiPSC-CMs we will study cellular processes, such as mitochondrial function and oxidative stress which have been recognized as main contributors for PA pathophysiology. In addition, our aim is to unravel novel altered pathways using high-throughput techniques such as RNAseq and miRNA analysis. We will also examine the potential beneficial effects of an antioxidant and a mitochondrial biogenesis activator in PA cardiomyocytes. The results that derive from this project will be relevant for the disease providing insight into the affected biological processes, and thus providing tools and models for the identification of novel adjuvant treatments for PA.

Update April 2020 – Eva Richard PhD

Thanks to propionic acidemia (PA) foundation, we have developed a new cellular model of PA based on induced pluripotent stem cells (iPSC) with the goal of defining new PA pathomechanisms which could be potential therapeutical targets. Traditionally, disease pathophysiology has been studied in immortalized or human cell lines and in animal models. Unfortunately, immortalized cells often do not respond as primary cells and animal models do not exactly recapitulate patients‘ clinical symptoms. So far, patients-derived fibroblasts have been mainly used as cellular models in PA due to their availability and robustness, but they have important limitations. The ability to reprogram somatic cells to iPSCs has revolutionized the way of modeling human disease. To study rare diseases,
stem cell models carrying patient-specific mutations have become highly important as all cell types can be differentiated from iPSCs.

We have generated and characterized two iPSC lines from patients-derived fibroblasts with defects in the PCCA and PCCB genes; and an isogenic control in which the mutation of the PCCB patient was genetically corrected using CRISPR/Cas9 technology. These iPSC lines have been successfully differentiated into cardiomyocytes,
and their presence was easily established by visual observation of spontaneously contracting regions and by the expression of several cardiac markers. PCCA iPSC-derived cardiomyocytes exhibited reduced oxygen consumption, an accumulation of residual bodies and lipid droplets, and increased ribosomal biogenesis. Furthermore, we found increased protein levels of HERP, GRP78, GRP75, SIG-1R and MFN2 suggesting
endoplasmic reticulum stress and calcium perturbations in these cells. We also analysed a series of heart-enriched miRNAs previously found deregulated in heart tissue of a PA murine model and confirmed their altered expression.

The present study represents the first report of the characterization of cardiomyocytes derived from iPSCs generated by PA patients ́ fibroblasts reprogramming. Our results provide evidence that several pathomechanisms may have a relevant role in cardiac dysfunction, a common complication in PA disease. This new cellular PA model offers a powerful tool to unravel disease mechanism and, potentially, to enable drug
screening/drug testing. Despite improved therapy over the past few decades, the outcome of PA patients is still unsatisfactory, highlighting the requirement to evaluate new therapies aimed at preventing or alleviating the clinical symptoms. Additional research is required to determine the contribution of the mechanisms identified in this work to the cardiac phenotype and how this knowledge can help formulating better personalized therapeutic
strategies in the future.

We sincerely thank the Propionic Acidemia Foundation for supporting our investigation, which has resulted in a truly motivating experience for us, feeling we belong to the PA research family. The funding we received has led to important advances in PA pathophysiology, and our aim is to continue this research in the near future.

Update September 2019 – Eva Richard PhD

There is an unmet clinical need to develop effective therapies for propionic acidemia (PA). Advances in supportive treatment based on dietary restriction and carnitine supplementation have allowed patients to live beyond the neonatal period. However, the overall outcome remains poor in most patients, who suffer from numerous complications related to disease progression, among them cardiac alterations, a major cause of PA morbidity and mortality. In our research, we developed a new cellular model of PA based on induced pluripotent stem cells (iPSC) with the goal of defining new molecular pathways involved in the pathophysiology of PA which would be potential treatment targeting.

Traditionally, disease pathophysiology has been studied in immortalized or human cell lines and in animal models. Unfortunately, immortalizedcells often do not respond as primary cells and animal models do not exactly recapitulate patients‘ symptoms. So far, patients-derived fibroblasts have been mainly usedas cellular models in PAdue to theiravailability and robustness, but they have important limitations.

The ability to reprogram somatic cells to iPSCs has revolutionized the way of modeling human disease. To study rare diseases, stem cell models carrying patient-specific mutations have become highly important as all cell types can be differentiated from iPSCs. We have generated and characterized two iPSC lines from patients-derived fibroblasts with defects in PCCA and PCCB genes. These iPSC lines can be differentiated into cardiomyocytes that mimic the tissue-specific hallmarks of the disease. The presence of PA cardiomyocytes has been easily established by visual observation of spontaneously contracting regions, and the expression of several cardiac markers. We have observed that PCCA-deficient cardiomyocytes present an increase in degradation products and in lipid droplets, and exhibit mitochondrial dysfunction compared to control cells. We further discovered the down-regulation of several miRNAs in PCCA cardiomyocytes compared to control ones, and several miRNAs targets are currently being analyzed in order to investigate underlying cellular pathological mechanisms. Interestingly, we have performed several experiments to analyze the effect of the mitochondrial biogenesis activator, MIN-102 compound (PPAR agonist, derivative of pioglitazone) in cardiomyocytes.

Preliminary results showed an increase in the oxygen consumption rateof PCCA and control cells. In our next steps, we plan to complete the analysis in the PCCA cardiomyocyte line, characterize PCCB cardiomyocytes and to study in depth the therapeutic potential of MitoQ and MIN-102 compounds.

We would like to sincerely thank the Propionic Acidemia Foundation for supporting our research.

Update March 2020

“Cardiomyocytes derived from induced pluripotent stem cells as a new model for therapy development in propionic acidemia.”

Eva Richard, Associate Professor

Traditionally, disease pathophysiology has been studied in immortalized or human cell lines and in animal models. Unfortunately, immortalized cells often do not respond as primary cells and animal models do not exactly recapitulate patients‘ symptoms. So far, patients-derived fibroblasts have been mainly used as cellular models in PA due to their availability and robustness, but they have important limitations.

The ability to reprogram somatic cells to iPSCs has revolutionized the way of modeling human disease. To study rare diseases, stem cell models carrying patient-specific mutations have become highly important as all cell types can be differentiated from iPSCs. We have generated and characterized two iPSC lines from patients-derived fibroblasts with defects in the PCCA and PCCB genes. These iPSC lines can be differentiated into cardiomyocytes that mimic the tissue-specific hallmarks of the disease. The presence of cardiomyocytes has been easily established by visual observation of spontaneously contracting regions, and the expression of several cardiac markers. PCCA iPSC-derived cardiomyocytes exhibited an alteration of autophagy process with an accumulation of residual bodies and mitochondrial dysfunction characterized by reduced oxygen consumption and alteration of mitochondrial biogenesis due to a deregulation of PPARGC1A. We also evaluated the expression of heart-enriched miRNAs previously associated with cardiac dysfunction and several miRNAs were found deregulated. Furthermore, we found increased protein levels of Herp, Grp78, Grp75, sigma-1R and Mfn2 suggesting ER stress and calcium perturbations in these cells.

We are planning to analyze PCCB cardiomyocytes to compare the results with PCCA and control data. We are working to obtain mature cardiomyocytes in order to perform electrophysiology studies (K+ currents) using a whole-cell patch clamp method. We are interested in the study of the tissue-specific bioenergetic signature comparing cardiomyocytes derived from control and PA patients´ iPSCs by reverse phase protein microarrays (RPPMA). Future work also includes testing the effect of the mitochondrial biogenesis activator, MIN-102 compound (PPAR agonist, derivative of pioglitazone) and of the mitochondrial targeting antioxidant MitoQ in PA cardiomyocytes.

We would like to sincerely thank the Propionic Acidemia Foundation for supporting our research.

Propionic Acidemia Foundation Research Grant Guofang Zhang

PAF Awards $48,500 Research Grant

Guofang Zhang, PhD, Duke University

“Propionyl-CoA and propionylcarnitine mediate cardiac complications in patients with propionic acidemia”

Energy production is the central cardiac metabolism for continuous mechanical work. An average human adult heart consumes ~ 6 kg ATP/day. ATP storage in the heart is only sufficient to sustain the heart beat for a few seconds. A tightly coupled cardiac energy metabolism from various substrates is critical for sufficient ATP production required by normal heart function.

One molecule of palmitic acid (fatty acid) generates much more ATP than one molecule of glucose does after their complete metabolism.Fatty acids contribute ~70-90% cardiac energy production in normal condition. However, heart still maintains high flexibility of fuel switch in response to various available substrates. Acetyl-CoA is the first convergent metabolite derived from the diverse fuel substrates via different pathways and enters tricarboxylic acid cycle (TCAC) for energy production. Therefore, the level of acetyl-CoA or the ratio of acetyl-CoA/CoA tightly controls the metabolic fluxes from two major fuels, i.e.,glucose and fatty acid, in the heart. Acetyl-CoA or CoA level is also finely tuned by carnitine acetyltransferase (CrAT) that catalyzes the reversible interconversion between short-chain acyl-CoAs and acylcarnitines.Acetylcarnitine level is ~10-100 fold greater than that of acetyl-CoA in heart and is seen as the buffer of acetyl-CoA. CrAT is highly expressed in high energy demanding organs including heart and mediates fatty acid and glucose metabolism possibly by dynamically interconverting acetyl-CoA and acetylcarnitine into each other.The deficiency of CrAT has been shown to change cardiac fuel selection.

Propionic acidemia (PA) is often associated with cardiac complications. However, the pathological mechanism remains unknown. We have demonstrated that high exogenous propionate led to the propionyl-CoA accumulation and cardiac fuel switch from fatty acid to glucose in the perfused normal rat hearts (Am. J Physiol. Endocrinol. Metab.,2018,315:E622-E633). The deficiency of propionyl-CoA carboxylase in PA also induces the accumulation of propionyl-CoA. Next, we will attempt to understand whether and how the elevated propionyl-CoA in the Pcca-/- heart (collaboration with Dr. Michael Barry)could interrupt cardiac energy metabolism by investigating the fuel switch flexibility, CrAT mediated metabolism, and buffer capacity of acetylcarnitine using stable isotope-based metabolic flux analysis (J. Biol. Chem., 2015,290:8121-32). We hope that the outcome of this project will provide meaningful therapeutic recommendation for patients with PA, especially with the cardiac complication.

Donations – Talli

Donate in Loving Memory of Talli Smith

Your gift supports our mission to find improved treatments and a cure for Propionic Acidemia by funding research and providing information and support to families and medical professionals. The Propionic Acidemia Foundation is a registered 501 (c) 3 non-profit organization. Contributions to Propionic Acidemia Foundation are tax deductible; however, consult with your tax advisor for your particular circumstances. Your gift makes a big impact.

Donate by mail by mailing a check to:

Propionic Acidemia Foundation

1963 McCraren Road

Highland Park, IL 60035

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Peter

Peter – updated 10/18/18

Peter

Hello, my name is Peter and I am 24 years old currently living in Rochester, New York. I have PA. During the first 4 weeks of my life, I was considered “fussy”, but nothing out of the ordinary. At 4 weeks, I experienced projectile vomiting, around the time my mom started supplementing breast milk with formula. I was admitted to the hospital and they believed it was due to my pyloric sphincter (the muscle at stomach opening) and they performed surgery. I stopped vomiting and my health improved for a few weeks, but hindsight suggests it is because I was placed on iv’s and was “cleaned out” during the surgical procedure.

At 6 weeks, I began having absence seizures and was re-admitted to the hospital. A diagnosis came two weeks later. The seizures were a result of extremely elevated glycine levels that crossed the blood/ brain barrier to spinal fluid. All they could do was start me on a non-offending diet and wait for the glycine to reduce. I was started on Propimex (my “special juice”), and 4 weeks later (still in the hospital) the seizures stopped and I was released from the hospital.

My early muscle tone was impacted and I did not walk until 18 months. Physically I seemed delayed but other development testing was favorable. They monitored my physical and mental development over several years.

Since my hospitalization as an infant I have never had a related metabolic “episode”, or any additional seizures or hospital stays.

My diet was supplemented with Propimex formula until I was about 4 years old. I was a vegetarian until 10 years old when I had my first hot dog! My favorite food was and still is pasta. I had bi-annual appointments at the metabolic clinic at the University of Rochester Medical Centerin which a dietician would suggest the amount of protein I should be eating. I took my lunch through my high school years to help control protein amounts. It was relatively easy to stay within the protein guidelines since I did not eat a lot of meat.

In high school, I began having rapid heart palpitations and sometimes struggled in gym class when we had to run long distances.I was sent to a pediatric cardiologist for a baseline EKG and had a slightly prolonged Q time.The doctors determined that I had metabolic induced cardiomyopathy. This has been noted in other PA patients.

I was treated with a low dose beta blocker and blood pressure medication to help manage blood flow and hopefully minimize tachycardia events.I have been monitored yearly and my Q time is now “high normal” along with a normal eco cardiogram for 2 years now. I have learned that if I exercise on a near empty stomach, I feel fine! I do have an occasional adrenaline induced tachycardia but I have learned to manage it bytaking deep breaths to stop it quickly.

I went away to college and graduated with both a Music Business / Vocal Performance Degree, and then followed with a second degree in Business Administration. I lived in the dorms, ate campus food, and had a great college experience! I really did not have any issue eating dormitory food as there were many vegetarian options available. I tend to self-regulate and really am not a big meat eater. I probably eat meat or fish2 to 3 times a week. By the way, I LOVE sushi.

I am currently employed as a National Sales Representative for a company which sells HR, payroll and other services to local businesses. Since middle school, I have been involved in musicals, opera productions, and a cappella groups.

With respect to my current medications, I currently take Levo carnitine and it can be a struggle to keep my free carnitine in the normal range. I have blood tests once per year and the only thing elevated is glycine and propionic acid levels. All other amino acids remain in the normal range. As mentioned I take a beta blocker and an ACE inhibitor.

I have yearly appointments at U of Rochester Med Center- Pediatric Genetics and also a yearly visit with the cardiologist. Over my lifetime U of R has struggled to keep a full time metabolic specialist on staff. My current physician covers both genetics and metabolics and is extremely busy.

I have never been genetically typed and I would love to support future research or disease understanding. My family and I are happy to share details to anyone who is interested.

That is my story, and I know that I am one of the lucky ones. I do hope that my story encourages parents and children learning to live with PA.

Thank you,

Novel therapies for Propionic acidemia – update Sept. 2018

Novel therapies for Propionic acidemia

Nicola Brunetti-Pierri, MD, Fondazione Telethon, Italy

This proposal was focused on the characterization of a fish model of propionic acidemia (PA) and on the development of novel therapies. The PA medaka fish model was found to recapitulate several clinical and biochemical features of the human disease, including reduced survival and locomotor activity, hepatic lipid accumulation, increased propionylcarnitine, methylcitrate, and propionate. Moreover, PA fishes showed better survival when fed with low-protein diet.

To gain insight into the disease pathogenesis and to search for potentially novel therapeutic targets, we performed an unbiased 3’-mRNA-Seq and NMR-based metabolome analyses. Both analyses showed global differences between PA and wild-type (wt) medaka. Interestingly, metabolism of glycine and serine resulted affected both at transcriptional and metabolites level and further studies are ongoing to investigate the role of these changes in the disease pathogenesis. Moreover, we found a marked increase in protein propionylation in PA fishes compared to wt controls. Protein propionylation is a post-translational modification occurring under normal conditions but its physiological role is unknown. Like protein acetylation, it is likely involved in regulation of gene expression, protein-protein interactions, and enzyme function. Interestingly, NAD-dependent sirtuins that are responsible of deacetylation of multiple proteins and have also de-propionylating activity, were significantly reduced in PA fishes. We speculated that aberrant protein propionylation in PA is toxic and proteomic studies are ongoing to reveal proteins with aberrant propionylation. With the support of this grant several drug candidates have been also investigated with the goal of developing new pharmacological approaches for PA.

In conclusion, we performed extensive phenotyping of the PA fish model that can be useful to unravel novel disease mechanisms and therapeutic targets.

updated September 2018