Podophyllotoxin-induced modifications of the nuclear envelope
1Department of Animal Biology, Faculty of Sciences, University C. A. Diop of Dakar, Senegal.
Journal of Structural Biology
|May 1, 1993
Summary
Podophyllotoxin disrupts microtubule-membrane interactions in Culex tigripes spermatids. This causes nuclear envelope bulging and abnormal vesicle formation where the manchette is absent.
Area of Science:
- Cell Biology
- Entomology
- Molecular Biology
Background:
- The manchette, a microtubule structure, surrounds the nucleus in insect spermatids.
- Understanding microtubule-membrane interactions is crucial for cell development.
Purpose of the Study:
- To investigate the effects of podophyllotoxin on spermatid manchette structure.
- To explore the role of microtubule-membrane relationships in nuclear envelope integrity.
Main Methods:
- Treatment of Culex tigripes spermatids with podophyllotoxin.
- Microscopic analysis of spermatid ultrastructure.
Main Results:
- Podophyllotoxin induced the absence of manchette microtubules in specific zones.
- Nuclear envelope bulging and extranuclear vesicle formation were observed in these zones.
- A correlation between microtubule absence and nuclear envelope abnormalities was noted.
Conclusions:
- Podophyllotoxin affects microtubule organization within spermatids.
- The study suggests a critical role for manchette microtubules in maintaining nuclear envelope stability.
- Podophyllotoxin's action highlights the importance of microtubule-membrane interactions.
Related Concept Videos
01:15Drugs that Stabilize Microtubules
Microtubules are dynamic structures that undergo cycles of catastrophe and rescue. The microtubules play a central role in cell division by forming the spindle apparatus for segregating the chromosomes. This makes them ideal targets for regulating dividing cells in tumors and malignant cancer cells. Microtubule stabilizing drugs help stabilize the microtubule formation and promote its polymerization. Paclitaxel was the first microtubule stabilizing agent used as anticancer drug in chemotherapy...
01:34Nuclear Protein Sorting
Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
01:45Regulation of Nuclear Protein Sorting
Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
01:32Pinching-off of Coated Vesicles
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
01:16Cellular Injury IV: Necrosis
Necrosis is a form of irreversible cell death caused by severe injury such as ischemia, toxins, or trauma. Unlike programmed cell death, it is an uncontrolled, pathological process that typically provokes inflammation in surrounding tissues.Pathophysiologic ChangesNecrosis begins when cells sustain critical damage, leading to swelling of organelles, particularly mitochondria, and rapid ATP depletion. As energy levels decline, membrane ion pumps fail, leading to calcium influx and eventually,...
01:22Cellular Injury V: Apoptosis and Autophagy
Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...