Lipidomic analysis of TRPC1 Ca2+-permeable channel-knock out mouse demonstrates a vital role in placental tissue sphingolipid and triacylglycerol homeostasis under high-fat diet

Abstract

Placental function including oxygen delivery and nutrient transport are critical determinants of fetal growth, moderating the risks of obesity and metabolic diseases later in life. Previously, we demonstrated in a mouse model that parental diet and exercise play important roles in placental lipid content and inflammation. Transient receptor potential canonical channel 1 (TRPC1) is a Ca2+-permeable integral membrane protein. We have demonstrated that TRPC1 increases total body adiposity in mice by decreasing the efficacy of exercise to limit adipose accumulation under a high fat (HF) diet. Importantly, intracellular calcium may regulate total body adiposity and increased total body adiposity could promote placental lipid accumulation. Similarly, intracellular calcium regulates membrane lipid content via the activation of the protein kinase C. Membrane lipids such as sphingomyelin are key regulators of cell signaling. Maternal HF diets increase placental tissue lipid concentrations resulting in compromised nutrient transport to fetus. However, the specific lipid species that accumulate due to the absence of the placental TRPC1 gene under maternal HF diet feeding is not yet known. We hypothesized that placental tissue response to a maternal HF diet is disrupted in TRPC1 mice fed a maternal HF diet resulting in greater cellular sphingomyelin concentrations. Results showed placentae from TRPC1 KO mice fed high fat diet (45% en, HF) had increased sphingomyelin concentrations compared to control diet (16% en, NF). Placentae from WT mice fed HF diet exhibited diet-dependent increases in ceramide concentration with no concomitant increase in sphingomyelins compared to NF fed WT mice. Additionally, 11 placental triacylglycerol (TAG) species were different based on diet, 16 based on genotype, and 5 were affected by both diet and genotype. These results suggest that during a HF diet, loss of TRPC1 function reduces placental sphingomyelin hydrolysis into ceramide and that placental TAG concentrations respond in diet- and genotype-dependent manner.