Nesfatin-1 Regulation of Cardiovascular Functions in Zebrafish and HL-1 Cardiomyocytes
Nesfatin-1 is an eighty two amino acid long peptide cleaved from the N-terminal of its precursor protein, nucleobindin-2 (NUCB2). In addition to its metabolic actions, nesfatin-1 is also involved in modulating cardiovascular functions in rodents. Intracereberoventricular injection of nesfatin-1 increased mean arterial pressure in rats. In rats, nesfatin-1 acts as a post-conditioning agent and elicits cardioprotection against ischemia-reperfusion injury. It also affects the contraction and relaxation of the heart in rats in a dose dependent manner. Nesfatin-1 is emerging as a regulator of cardiovascular functions in rodents. However, whether nesfatin-1 regulates the cardiovascular system of non-mammals remain unknown. We hypothesized that nesfatin-1 is a modulator of cardiovascular functions in zebrafish. Here we characterized endogenous nesfatin-1 in zebrafish heart, and its effects on zebrafish cardiovascular physiology. We found that zebrafish cardiomyocytes express NUCB2 mRNA and nesfatin-1-like immunoreactivity. While NUCB2 mRNA was lower in unfed fish at 1 hour post-regular feeding time compared to the fish at 0 hour time point, it was observed that chronic food deprivation did not alter NUCB2 mRNA expression in zebrafish heart. Ultrasound imaging of zebrafish heart at 15 minutes post-intraperitoneal injection of nesfatin-1 (50 ng/g, 250 ng/g and 500 ng/g body weight) showed a dose-dependent inhibition of end-diastolic volume, but not end-systolic volume, while a significant increase in end-diastolic volume was found at the lowest dosage. However, these combined effects did not alter the stroke volume. A dose dependent decrease in heart rate and cardiac output was observed in zebrafish that received nesfatin-1. Nesfatin-1 caused a significant increase in the expression of Atp2a2a mRNA encoding the calcium-handling pump, SERCA2a, while it has no effects on the expression of calcium handling protein RyR1b encoding mRNA. NUCB2 mRNA and NUCB2/nesfatin-1 like immunoreactivity was detected in the cytoplasm of mouse HL-1 cardiomyocytes. High glucose increased NUCB2 mRNA expression in HL-1 cells. Genes involved in apoptosis, including Akt1, Caspases 1, 2, 3, and TNF were upregulated in the presence of 10 nM nesfatin-1. We also observed that NUCB2 mRNA expression was significantly increased in C57BL/6 mice heart in the presence of high glucose, whereas in diet induced obese C57BL/6 mice, NUCB2 mRNA expression was not altered. Together, our data supports the hypothesis that nesfatin-1 is expressed in the cardiovascular system of mouse and fish, and that nesfatin-1 modulates cardiovascular physiology in zebrafish.
DegreeMaster of Science (M.Sc.)
DepartmentVeterinary Biomedical Sciences
ProgramVeterinary Biomedical Sciences
SupervisorUnniappan, Dr. Suraj
CommitteeWeber, Dr. Lynn P.; Machin, Dr. Karen; Ndisang, Dr. Joseph
Copyright DateDecember 2014