Steroid receptor coactivator 1 is an integrator of glucose and NAD+/NADH homeostasis.
Steroid receptor coactivator 1 (SRC-1) drives diverse gene expression programs necessary for the dynamic regulation of cancer metastasis, inflammation and gluconeogenesis, pointing to its overlapping roles as an oncoprotein and integrator of cell metabolic programs. Nutrient utilization has been intensely studied with regard to cellular adaptation in both cancer and noncancerous cells. Nonproliferating cells consume glucose through the citric acid cycle to generate NADH to fuel ATP generation via mitochondrial oxidative phosphorylation. In contrast, cancer cells undergo metabolic reprogramming to support rapid proliferation. To generate lipids, nucleotides, and proteins necessary for cell division, most tumors switch from oxidative phosphorylation to glycolysis, a phenomenon known as the Warburg Effect. Because SRC-1 is a key coactivator responsible for driving a hepatic gluconeogenic program under fasting conditions, we asked whether SRC-1 responds to alterations in nutrient availability to allow for adaptive metabolism. Here we show SRC-1 is stabilized by the 26S proteasome in the absence of glucose. RNA profiling was used to examine the effects of SRC-1 perturbation on gene expression in the absence or presence of glucose, revealing that SRC-1 affects the expression of complex I of the mitochondrial electron transport chain, a set of enzymes responsible for the conversion of NADH to NAD(+). NAD(+) and NADH were subsequently identified as metabolites that underlie SRC-1's response to glucose deprivation. Knockdown of SRC-1 in glycolytic cancer cells abrogated their ability to grow in the absence of glucose consistent with SRC-1's role in promoting cellular adaptation to reduced glucose availability.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030.
Massoud
M
Motamed
Kimal I
KI
Rajapakshe
Sean M
SM
Hartig
Cristian
C
Coarfa
Robb E
RE
Moses
David M
DM
Lonard
Bert W
BW
O'Malley
D045744:Cell Line, Tumor; D002470:Cell Survival; D042967:Electron Transport Complex I / Q000378:metabolism; D004734:Energy Metabolism; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D009243:NAD / Q000378:metabolism*; D056920:Nuclear Receptor Coactivator 1 / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D055550:Protein Stability; D059748:Proteolysis
D009243:NAD; D056920:Nuclear Receptor Coactivator 1; D046988:Proteasome Endopeptidase Complex; D042967:Electron Transport Complex I; D005947:Glucose