Related Experiment Video
Updated: Aug 5, 2026
06:39
Glomerular Outgrowth as an Ex Vivo Assay to Analyze Pathways Involved in Parietal Epithelial Cell Activation
Published on: August 19, 2020
PGF2alpha-induced signaling events in glomerular mesangial cells
B A Breshnahan1, D Kelefiotis, I Stratidakis
1Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Summary
Prostaglandin F2alpha (PGF2alpha) activates mesangial cell signaling pathways, including phospholipase C (PLC) and protein kinase C (PKC). PKC negatively regulates PGF2alpha-induced PLC activation, revealing a novel feedback mechanism in renal cells.
Area of Science:
- Renal physiology and cell signaling
- Eicosanoid metabolism and function
- Molecular mechanisms of cell regulation
Background:
- Prostaglandin F2alpha (PGF2alpha) is a key eicosanoid in renal glomerular capillaries, influencing mesangial cell contraction and proliferation.
- The regulatory mechanisms of PGF2alpha-induced signaling in mesangial cells remain largely uncharacterized.
- Understanding these pathways is crucial for comprehending renal function and disease.
Purpose of the Study:
- To investigate the signaling events of phospholipase C (PLC) and protein kinase C (PKC) activation in response to PGF2alpha in mesangial cells.
- To elucidate the mechanisms regulating PGF2alpha-induced PLC activation.
- To identify the role of PKC in modulating these signaling pathways.
Main Methods:
- Cultured rat mesangial cells were stimulated with PGF2alpha.
- Phosphatidyl inositol-specific phospholipase C (PI-PLC) activation was assessed by measuring inositol phosphate generation and diacylglycerol (DAG) mass.
- Protein kinase C (PKC) activation was measured by enzyme translocation. Inhibitors of PKC, protein tyrosine phosphorylation, and G-proteins were used to explore regulatory mechanisms.
Main Results:
- PGF2alpha activated PI-PLC, leading to increased inositol trisphosphate (IP3) and DAG generation in a biphasic manner.
- PGF2alpha also activated PKC, evidenced by its translocation to membrane fractions.
- PKC inhibition enhanced PGF2alpha-induced IP3 generation but attenuated late DAG generation, suggesting PKC negatively regulates PI-PLC and positively regulates another phospholipase.
Conclusions:
- PGF2alpha stimulates PI-PLC and a distinct PKC-regulated phospholipase in mesangial cells.
- PKC exerts negative feedback control on PGF2alpha-induced PI-PLC activation.
- PGF2alpha-induced PI-PLC activation is independent of protein tyrosine phosphorylation and pertussis toxin-sensitive G-proteins.
Related Concept Videos
01:15Amplifying Signals via Second Messengers
Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
01:22Amplifying Signals via Enzymatic Cascade
When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze the...
01:16TGF - β Signaling Pathway
The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...
01:22Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
01:25cAMP-dependent Protein Kinase Pathways
Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...