Jennifer Perpar
Glycogen Synthase Kinase-3ß (GSK-3ß) in Human Heart Failure

SchoolLake Catholic High School


ProgramScience


MentorChristine Moravec, PhD


DepartmentMolecular Cardiology


Research
Glycogen Synthase Kinase-3ß (GSK-3ß) in Human Heart Failure
Hypothesis
Because we have previously shown changes in pGSK-3ß in human heart failure, we hypothesize that it will also be altered in hearts exhibiting two transition states: left ventricular hypertrophy (LVH), which leads to heart failure, and hearts which have been supported by a left ventricular assist device (LVAD), in which reversal of the heart failure phenotype has been shown.
Methodology
After IRB approval (IRB 2378), 120 patients were selected for the study and were divided into groups: NF, LVH, HF and LVAD. In a subset of patients receiving an LVAD, protein expression was measured in tissue samples taken at insertion of the LVAD device (Core) and at the time of transplantation (Tx). Patient characteristics are defined in Table 2. Left ventricular tissue samples were homogenized in RIPA buffer. Total heart homogenate concentration was measured by Lowry protein assay. Samples were loaded into 4% stacking gels and 8% resolving gels and were separated by gel electrophoresis. Proteins were transferred from the gel to PVDF membrane. Membranes were blocked in 5% non-fat milk for 1 hour and then incubated in primary antibody for pGSK-3ß, GSK-3ß or GAPDH at 4ºC overnight. (See Table 1. for antibody concentrations.) Membranes were incubated in goat anti-rabbit secondary antibody for 1 hour at room temperature. (See Table 1 for antibody concentration.) Membranes were scanned using the Odyssey near-infrared digital scanner. Band densities were quantified using Odyssey software. Data are represented as mean ± SEM. Groups were compared using a two-way ANOVA and Bonferroni post-hoc tests.
Outcomes
GSK-3ß is an important inhibitor in many pathways that lead to hypertrophy of the heart. Phosphorylation of GSK-3ß interferes with its ability to prevent hypertrophy. Elevated levels of pGSK-3ß in male LVH inhibits GSK-3ß and allows pro-hypertrophic signaling to occur in the heart, potentially resulting in left ventricular wall thickening. It is not clear why female LVH hearts do not show the same elevation, and this finding remains to be explored. Our lab and others have previously shown remodeling of many changes associated with HF in patients supported by an LVAD. The current data support the hypothesis that LVAD support normalizes signaling pathways associated with heart failure. Decreased GSK-3ß protein in LVAD-supported hearts remains to be investigated further.