Excellgen

Cre Recombinase

Published

What is Cre Recombinase and Its Basic Function?

  • Cre recombinase (often abbreviated to Cre) is a Type I topoisomerase derived from the P1 bacteriophage.

  • It catalyzes site-specific recombination between 34 base pair (bp) recognition sites known as loxP sites.

  • This recombination:

    • Does not require energy cofactors

    • Rapidly reaches equilibrium between substrates and products

  • The outcome depends on the location and orientation of the loxP sites:

    • Same orientation on the same DNA: the intervening sequence is excised in circular form (deletion of "floxed" DNA).

    • Opposite orientation on the same DNA: the intervening sequence is inverted.

    • On different DNA molecules: can result in insertion or translocation.

  • The specificity of Cre/loxP is high due to the rarity of exact loxP sites in mammalian genomes, ensuring recombination is limited to introduced loxP sites.

Cre Recombinase Applications (Current Status)

Cre recombinase is widely used in gene and chromosome modification, serving as a universal genome editing tool in research, particularly in mouse models and increasingly in plants.

Key Applications:

  • Conditional Gene Knockout

    Delete a DNA segment flanked by loxP sites in specific cells or tissues:

    • Controlled by tissue-specific or inducible promoters

    • Useful for genes causing embryonic lethality if knocked out globally

      Examples:

      • Glucokinase-expressing tanycyte ablation in mice (Gck deletion)

      • Mouse model of pleomorphic liposarcoma via Cre-mediated silencing of Trp53, Rb1, and Pten

  • Conditional Transgenesis

    Activate transgene expression by removing a loxP-flanked STOP sequence.

  • Selectable Marker Removal

    Excise marker genes post-targeting to:

    • Avoid interference with nearby genes

    • Reuse vectors to make homozygous knockouts

  • Introducing Subtle Genetic Changes

    Combine homologous recombination and Cre-mediated marker excision.

  • Creating Hypomorphic Alleles

    Insert markers with cryptic splice sites to reduce gene expression.

  • Conditional Gene Repair

    Rescue function of a disrupted gene in a lineage- or tissue-specific manner.

  • Generating Chromosomal Aberrations

    Induce deletions, inversions, or translocations at defined loci.

  • Site-Specific DNA Insertion (Pop-In)

    Insert DNA into target genomic loci using loxP recombination, sometimes with mutant lox sites (e.g., lox511) to promote insertion.

  • Cell Lineage Tracing

    Use inducible Cre (e.g., Cre-ER) and Cre-dependent reporters to track cell fate.

  • Brain Research

    Extensively used in neuroscience to study:

    • Neural circuits

    • Brain cell types

    • Cognition and behavior

      NIH Blueprint has generated hundreds of Cre driver lines for this purpose.

  • Disease Modeling

    Engineer models that mimic human disease with intact immune systems for preclinical drug testing.

  • Plant Genome Editing

    Used for removal of transgenes or CRISPR components in plant systems. Helps in regeneration and fertility of edited plants.

  • In vitro Applications

    • Subcloning

    • Clone/vector engineering

    • Transduction into cultured cells, including ex vivo stem cells

Excellgen’s Cre Recombinase

Products:

  • TAT-Cre (EG-1021, EG-1001)

  • Lyophilized TAT-Cre (EG-8)

Features:

  • Cell-permeant fusion Cre protein purified from E. coli

  • Includes TAT peptide and nuclear localization signal (NLS) for efficient delivery

Applications:

  • In vitro loxP recombination for vector engineering

  • Transduction into cultured cells

  • In vivo recombination by direct injection in mice (e.g., brain or muscle)

Current Status and Future Opportunities

Current Status

  • Widely adopted for precise genetic manipulation

  • Tissue-specific and inducible Cre lines are common

  • Used to create sophisticated animal disease models

  • Key tool in plant gene editing, especially for removing other editing elements

Future Opportunities

  • Develop more reliable and specific Cre transgenic lines:

    • Use better promoters

    • Employ site-specific knock-in strategies

  • Enhance temporal control:

    • Improve inducible systems like Cre-ER

  • Improve recombination efficiency and reduce off-target effects:

    • Particularly important for plant systems

    • Address effects of DNA methylation

  • Expand disease modeling applications for novel therapy testing

  • Broaden use in plant biotechnology for more precise gene control

  • As CRISPR advances, Cre-lox remains valuable for conditional/site-specific modifications

  • Demand continues to rise with growth in molecular biology and biotech sectors, even if it's considered part of broader tech categories