Effects of elevated intracellular magnesium on cytoskeletal integrity

Area of Science:

• Cell Biology
• Cytoskeletal Dynamics

Background:

• The cytoskeleton, composed of microtubules, actin filaments, and intermediate filaments, is crucial for cellular structure and function.
• Understanding how cellular components influence cytoskeletal organization is vital for cell biology research.

Purpose of the Study:

• To investigate the effects of elevated intracellular magnesium concentration on the cytoskeleton of PtK2 cells.
• To determine the specificity and reversibility of magnesium-induced cytoskeletal changes.

Main Methods:

• Microinjection of magnesium into PtK2 cells.
• Immunofluorescence microscopy of fixed and living cells.
• Use of rhodamine-tubulin and rhodamine-conjugated anti-tubulin antibodies.
• Image intensification and enhancement techniques.

Main Results:

• A 1 mM or greater increase in intracellular magnesium caused rapid (5 min) disassembly of interphase microtubule arrays.
• F-actin stress fibers also disappeared, while peripheral and perinuclear F-actin microfilaments remained intact.
• Vimentin intermediate filaments were unaffected by increased magnesium.
• The observed effects were transient and fully reversible upon normalization of magnesium levels.
• Elevated intracellular calcium mimicked microtubule disassembly but not F-actin stress fiber disruption.

Conclusions:

• Elevated intracellular magnesium specifically and reversibly disrupts microtubule and F-actin stress fiber organization in PtK2 cells.
• These findings highlight the sensitivity of specific cytoskeletal components to magnesium ion concentration.
• The cytoskeleton's dynamic response to magnesium provides insights into cellular regulation and potential therapeutic targets.