This application describes an approach to better understand the structure of the interaction between the Krebs/Tricarboxylic acid (TCA) cycle and the propionate pathway. Then it uses enzymatic assays to probe the function of proteins at the intersection of these pathways. Finally it examines samples from subjects with propionate disorders to better characterize this structure and function. The Problem: Although Krebs/TCA cycle was identified greater than 80 years ago and the propionate pathway disorders were identified greater than 40 years ago, their structural interaction has not been described. Individuals with propionate disorders have long term complications which implicate energy production and this interaction between propionate pathway and Krebs/TCA cycle may provide a site of therapy. By understanding how these pathways intersect-we suspect as an physical association-- and assay them as a whole system, we are looking for possible sites for therapeutics. The Approach: To characterize this interaction, we aim to isolate the association formed at the intersection of these pathways. We then will probe this structure for function by using existing assays to determine if they can be used as screening assays. Finally we aim to see how the structure and function differs in cells from individuals/mice with the propionate pathway disorders, propionic acidemia and methylmalonic aciduria. Anticipated Results: We have preliminary data that shows the Krebs/TCA cycle enzymes, succinate synthase and oxoglutarate dehydrogenase complex, interact with the propionate pathway enzyme, methylmalonyl CoA as a complex. We anticipate that we will be able to isolate the association involving the propionate pathway and Krebs/TCA cycle enzymes and it will be associated with inner mitochondrial membrane.
We aim to isolate the interaction and be able to assay it using pre-existing methods designed for individual enzymes. These assays and isolation of a complex will inform us of possible sites for therapeutics and a method for screening small molecules. Finally, we will be able to assay tissues and cells from individuals and mice with propionate pathway disorders and be able to identify differences and potentially new sites for therapeutics for these disorders.

Public Health Relevance

We suspect that the Krebs/tricarboxylic acid cycle and propionate pathway, two energy producing pathways that intersect, interact as an association. Here we propose identifying components of this association and then assaying the components as an association. Identifying the components of this association and screening the association for enzyme activity provides a mechanism to screen new treatments for propionate pathway disorders such as propionic acidemia and methylmalonic aciduria, as well as other disorders which affect the Krebs/TCA cycle's function.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Clinical Investigator Award (CIA) (K08)
Project #
1K08DK105233-01A1
Application #
9032934
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Hyde, James F
Project Start
2015-09-18
Project End
2018-07-31
Budget Start
2015-09-18
Budget End
2016-07-31
Support Year
1
Fiscal Year
2015
Total Cost
$144,612
Indirect Cost
$10,712
Name
Children's Research Institute
Department
Type
DUNS #
143983562
City
Washington
State
DC
Country
United States
Zip Code
20010
Blask, Anna R; Rubio, Eva I; Chapman, Kimberly A et al. (2018) Severe nasomaxillary hypoplasia (Binder phenotype) on prenatal US/MRI: an important marker for the prenatal diagnosis of chondrodysplasia punctata. Pediatr Radiol 48:979-991
Chapman, Kimberly A; Gramer, Gwendolyn; Viall, Sarah et al. (2018) Incidence of maple syrup urine disease, propionic acidemia, and methylmalonic aciduria from newborn screening data. Mol Genet Metab Rep 15:106-109
Chapman, Kimberly A; Ostrovsky, Julian; Rao, Meera et al. (2018) Propionyl-CoA carboxylase pcca-1 and pccb-1 gene deletions in Caenorhabditis elegans globally impair mitochondrial energy metabolism. J Inherit Metab Dis 41:157-168
Wilson, Kirkland A; Han, Yong; Zhang, Miaoqi et al. (2017) Inter-relations between 3-hydroxypropionate and propionate metabolism in rat liver: relevance to disorders of propionyl-CoA metabolism. Am J Physiol Endocrinol Metab 313:E413-E428
Weinstein, Veronique; Tanpaiboon, Pranoot; Chapman, Kimberly A et al. (2017) Do the data really support ordering fragile X testing as a first-tier test without clinical features? Genet Med 19:1317-1322
Wongkittichote, Parith; Ah Mew, Nicholas; Chapman, Kimberly A (2017) Propionyl-CoA carboxylase - A review. Mol Genet Metab 122:145-152
Chapman, Kimberly A; Collado, Maria S; Figler, Robert A et al. (2016) Recapitulation of metabolic defects in a model of propionic acidemia using patient-derived primary hepatocytes. Mol Genet Metab 117:355-362
Li, Zejuan; Schonberg, Rhonda; Guidugli, Lucia et al. (2015) A novel mutation in the promoter of RARS2 causes pontocerebellar hypoplasia in two siblings. J Hum Genet 60:363-9