Intracellular immunization with cytosolic recombinant antibodies

Area of Science:

• Molecular Biology
• Cell Biology
• Immunology

Background:

• Cellular protein function is crucial for biological processes.
• Targeting specific proteins is key to understanding cellular mechanisms.
• Intracellular protein inactivation offers a novel research approach.

Purpose of the Study:

• To develop a strategy for inactivating cellular proteins via intracellular antibody expression.
• To investigate the inhibition of p21 protein function using recombinant antibodies.
• To assess the impact of intracellular antibody expression on oocyte meiotic maturation.

Main Methods:

• Cloning variable regions of anti-p21ras monoclonal antibody Y13-259 into expression vectors.
• Engineering recombinant antibodies (whole molecule or single-chain Fv fragment) for cytosolic expression by mutating or deleting leader sequences.
• Expressing recombinant antibodies in Xenopus laevis oocytes and analyzing their localization and functional effects on H1 kinase activity and meiotic maturation.

Main Results:

• Recombinant antibodies expressed in the cytosol colocalized with endogenous p21ras protein at the oocyte plasma membrane.
• Intracellularly expressed anti-p21ras antibodies significantly inhibited insulin-induced H1 kinase activity.
• Cytosolic anti-p21ras single-chain Fv fragments effectively blocked meiotic maturation in oocytes.

Conclusions:

• Intracellular expression of immunoglobulin genes provides a viable strategy for cellular protein inactivation in vertebrate cells.
• This approach allows for targeted inhibition of specific proteins like p21ras.
• The method demonstrates the potential to block biological functions by interfering with protein activity through engineered antibodies.