Formation and ultrastructure of somatic cell hybrids

Area of Science:

• Cell Biology
• Microscopy
• Genetics

Background:

• Cell fusion is a fundamental biological process.
• Understanding the structural dynamics during cell fusion is crucial for cell biology and genetic engineering.

Purpose of the Study:

• To investigate the structural alterations in mammalian somatic cells during viral, PEG-induced, and spontaneous fusion using electron microscopy (EM).
• To correlate these structural changes with the efficiency, rate, and mode of hybrid nucleus formation and genome stability.

Main Methods:

• Electron microscopy (EM) was employed to examine the ultrastructure of fusing mammalian somatic cells.
• Analysis focused on cell surfaces, nuclear envelopes, and cytoplasmic organelles.

Main Results:

• Both induced (viral, PEG) and spontaneous cell fusion result in specific structural modifications of fusing cells.
• PEG treatment alters cell surfaces, nuclear envelopes, and organelles.
• Virally-induced heterokaryons exhibit retained plasma membrane remnants.
• Hybrid nuclei show finger-like invaginations of the nuclear envelope, potentially counteracting volume-surface area disproportion and enhancing chromatin anchorage, particularly in multichromosomal hybrids with minimal chromosome loss.

Conclusions:

• Structural alterations are specific responses to fusion challenges, influencing fusion efficiency, rate, and hybrid nucleus formation.
• Nuclear envelope invaginations may represent a mechanism to maintain genome stability in hybrid cells.
• These findings provide insights into the structural basis of successful mammalian cell fusion and hybrid genome integrity.