Item Details

abstract

Obesity is a growing health concern and identifying genetic and environmental risk factors is crucial for understanding the disease and possible therapies. Using the heterogeneous stock (HS) rat (a genetically diverse outbred rat model) we identified G-protein coupled receptor kinase 5 (Grk5) as a candidate causal gene for adiposity with a positive correlation between GRK5 expression and retroperitoneal fat pad size. GRK5 is a member of a family of kinases responsible for phosphorylation of G-protein-coupled receptors (GPCR) and turning off downstream signaling, including beta-2-adrenergic receptor (β2-AR) signaling. A previous study has shown that GRK5 whole body knockout (KO) mice are protected against diet-induced obesity, possibly through decreased adipogenesis and fat storage. To better understand the mechanistic role of GRK5 in adiposity, we have generated a mouse GRK5-KO 3T3-L1 pre-adipocyte cell model using CRISPR-Cas9 gene editing. We hypothesize that a GRK5 deletion would lead to less adipocyte differentiation and decreased lipid anabolism. During white and brown adipogenic stimulation, the GRK5-KO cells show hindered lipid storage evident in decreased total cellular triacylglycerol (TAG) content and white/brown adipocyte-specific gene expression, compared to wild-type (WT) cells). Ablation of GRK5 also resulted in decreased fatty acid uptake and use in lipid synthesis in 3T3-L1 white adipocytes. As a result of impaired adipocyte differentiation and lipid storage, GRK5-KO cells have insufficient lipolysis compared to WT cells. Lastly, we observed that GRK5 deficient pre-adipocytes had increased insulin-stimulated AKT phosphorylation, the downstream signaling molecule of insulin-like growth factor I receptor (IGF1R). A previous study demonstrates that GRK5 functions to phosphorylate IGF1R and turn off downstream signaling. Together, these results indicate that deletion of GRK5 results in an increase of pre-adipocyte proliferation and suppression of adipocyte differentiation, possibly through hyper-activation of IGF1R in pre-adipocytes.

subject

adipogenesis

GRK5

insulin signaling

lipogenesis

lipolysis

contributor

McDonald, Bailey Thomas (author)

Solberg Woods, Leah C (committee chair)

Chuang Key, Chia-Chi (committee member)

Yammani, Raghunatha (committee member)

date

2022-05-24T08:36:15Z (accessioned)

2022 (issued)

degree

Biomedical Science – MS (discipline)

2024-05-23 (liftdate)

embargo

2024-05-23 (terms)

identifier

http://hdl.handle.net/10339/100776 (uri)

language

en (iso)

publisher

Wake Forest University

title

THE ROLES OF G-PROTEIN COUPLED RECEPTOR KINASE 5 IN ADIPOCYTE DIFFERENTIATION AND LIPID METABOLISM USING A 3T3-L1 CELL MODEL

type

Thesis