2. Transposons, commonly referred to as "jumping genes," are genetic elements within
DNA that have the capacity to relocate within a genome, achieved either through self-
replication (in the case of retrotransposons) or by excising and subsequently
reintegrating themselves (in the case of DNA transposons). These elements hold a
significant role in shaping genetic diversity, driving evolutionary processes, and
influencing the regulation of genes.
DNA transposons move from one genomic location to another by a cut-and-paste
mechanism. They are powerful forces of genetic change and have played a significant
role in the evolution of many genomes. As genetic tools, DNA transposons can be
used to introduce a piece of foreign DNA into a genome.
3. Transposons were first discovered in corn (maize) during the 1940s and ’50s by American
scientist Barbara McClintock, whose work won her the Nobel Prize for Physiology or Medicine
in 1983. Since McClintock’s discovery, three basic types of transposons have been identified.
These include class II transposons, miniature inverted-repeat transposable elements (MITEs,
or class III transposons), and retrotransposons (class I transposons).
repetitive structure featuring terminal repeats at both ends, which enable their mobility. They
contain a transposase gene encoding the enzyme responsible for their movement, using
either cut-and-paste or copy-and-paste mechanisms. Additionally, transposons often carry
cargo DNA, which can encompass various genetic sequences or genes that they may transfer
and insert into new genomic locations.
4. Miniature inverted-repeat
transposable elements
• MITEs are compact DNA
sequences with short,
inverted terminal repeats
found in genomes.
• They lack coding capacity
for transposase enzymes
and often rely on the
transposases of other
transposons for mobility.
• Despite their simplicity,
MITEs contribute to genomic
diversity, influence gene
expression, and play a
significant role in genome
evolution and regulation.
Class II transposons Retrotransposons
• genetic elements that use a
cut-and-paste mechanism
of transposition.
• They have inverted
terminal repeats that aid
their mobility and do not
self-replicate.
• These transposons can
move as DNA segments,
excising themselves from
one genomic location and
inserting into another,
causing genetic material to
be rearranged.
• use a "copy-and-paste"
method to replicate
themselves in new
genomic locations.
• They lack terminal
repeats and are
categorized as LTR and
non-LTR
retrotransposons.
• As a significant portion
of eukaryotic genomes,
they affect genetic
diversity and evolution.
6. because of their unpredictable and sometimes disruptive
behavior within a genome. They can "play tricks" on the
genetic material by jumping from one location to another,
causing mutations, duplications, deletions, and other
genetic changes. This unpredictability and their ability to
introduce variations in the genetic code make them seem
like "jokers" in the deck of genetic cards. While they can
have significant evolutionary implications, their impact
can also be perceived as capricious or whimsical, which
is where the nickname "genetic jokers" comes from.
7.
8. Our perception of the role of the previously considered ‘selfish’ or ‘junk’ DNA has
been dramatically altered in the past 20 years or so.They play a vital role in
genome stability maintenance and contribute to genomic diversity and evolution.
• Cancer results from accumulating somatic mutations, with mouse models
supporting this concept by showing that multiple mutations are required for
tumor development.
• Retroviruses promote tumors by integrating proviruses into the host genome,
causing mutations in tumor suppressor genes or oncogenes, leading to
common integration sites (CIS).
• DNA transposons like Sleeping Beauty (SB) offer an alternative approach to
identify cancer genes, but they are rare in vertebrate genomes.
• SB, initially engineered from dormant DNA transposons in salmonid fish, has
been shown to be active in various contexts, including zebrafish, human cells,
and mice.
9. • Crossbreeding mice with transposase and
transposon genes results in active
transposons, leading to the development
of tumors, particularly in the hematopoietic
system.
• Tumor analysis revealed common
integration sites (CIS) and genetic
interactions between cancer genes.
• SB provides a valuable tool for cancer
gene discovery in tissues not previously
amenable to genetic screens, and future
improvements to the system hold promise.
• The SB system can contribute to the
creation of diverse, evolving mouse tumor
models for drug discovery, more
accurately reflecting the genetic
complexity of human cancer.
10. Munoz-Lopez Martin and Garcia-Perez L. Jose, DNA Transposons: Nature and
Applications in Genomics, Current Genomics 2010; 11 (2) .
https://dx.doi.org/10.2174/138920210790886871
https://www.britannica.com/science/transposon
Dubin, M. J., Scheid, O. M., & Becker, C. (2018). Transposons: a blessing curse. Current
opinion in plant biology, 42, 23-29.
Ivics, Z., & Izsvak, Z. (2006). Transposons for gene therapy!. Current gene therapy, 6(5),
593-607.
Copeland, N. G., & Jenkins, N. A. (2010). Harnessing transposons for cancer gene
discovery. Nature Reviews Cancer, 10(10), 696-706.
Collier, L. S., & Largaespada, D. A. (2005). Hopping around the tumor genome:
transposons for cancer gene discovery. Cancer research, 65(21), 9607-9610.
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