Xylosylated-proteoglycan-induced Golgi alterations.

Area of Science:

• Renal physiology
• Cell biology
• Biochemistry

Background:

• Proteoglycans (PGs) are crucial components of the glomerular extracellular matrix.
• The Golgi apparatus is central to PG synthesis and modification.
• Disruptions in PG synthesis can impact kidney function.

Purpose of the Study:

• To investigate the effects of p-nitrophenyl beta-D-xylopyranoside (beta-xyloside) on Golgi apparatus and proteoglycans in the renal glomerulus.
• To understand the cellular and extracellular distribution of newly synthesized PGs under beta-xyloside treatment.

Main Methods:

• Isolated kidney organ perfusion system.
• [35S]sulfate labeling to trace PG synthesis.
• Electron microscopy and autoradiography to visualize cellular and extracellular changes.
• Biochemical analysis of PG molecular weight and distribution.

Main Results:

• Beta-xyloside induced intracytoplasmic vesiculization of the Golgi apparatus in glomerular visceral epithelial cells.
• [35S]sulfate incorporation increased intracellularly (2.3-fold) and decreased extracellularly (1.7-fold).
• Lower molecular weight PGs and free glycosaminoglycans accumulated intracellularly and in the media.
• A significant increase (3.8-fold) in radioactivity was observed in the media fraction, associated with small PGs and glycosaminoglycans.

Conclusions:

• Beta-xyloside causes a significant imbalance in de novo PG synthesis between cellular and extracellular compartments.
• Accumulation of xylosylated PGs within cells selectively alters the Golgi apparatus of glomerular epithelial cells.
• These findings highlight the critical role of glomerular epithelial cells in PG synthesis and the impact of altered synthesis on cellular structures.