Motherless Mice Created Using Epigenetic Reprogramming

Researchers at Shanghai Jiao Tong University successfully created mice from the DNA of two male parents. 

• This was achieved by editing the epigenome, specifically the methylation pattern, in sperm cells. 
• The result was a healthy and fertile motherless mouse, which demonstrates the potential of epigenetic programming in reproductive biology.

DNA Editing Technologies

• The experiment relied on the use of CRISPR and CAS, powerful genome-editing technologies.
  • These tools enable scientists to target specific genes in a DNA sequence, either by removing, adding, or altering them. 

• Normal Reproduction Process: Typically, when an embryo is formed, it receives one set of DNA from the mother (through the egg) and another from the father (through the sperm).
• Experimental Approach: In this study, scientists deleted the DNA of the egg, then injected the egg with two sperm heads from two male mice. 
• Epigenetic Reprogramming: One of these sperm cells was then edited using epigenetic techniques to alter its methylation pattern, effectively mimicking the DNA of the mother. 
• Embryo Implantation: After reprogramming the sperm’s DNA, the embryo was implanted into a female mouse, which carried the pregnancy.
• Limitations: 
• • Limited Success: Out of 250 reprogrammed embryos that carried DNA from two males, only 16 of them led to pregnancies and only three live births of male mice.
  • Editing the DNA to put in deletions are said to have adversarial health impacts on the genetically modified offspring mice.

About Genomic Imprinting

• Genomic Imprinting is a process by which mammals are known to chemically modify DNA sequence.
  • In the process only one copy of a gene in an individual (either from their mother or their father) is expressed, while the other copy is suppressed.
  • Prader-Willi Syndrome and Angelman Syndrome are classic examples of disorders caused by imprinting errors on chromosome 15.
• Features: 
  • Gender Based Modification: Males imprint their DNA by adding methyl modifications in order to alter the activity of genes and promote the growth of embryos,
    • While Females make chemical modifications to shut down certain genes for the same purpose.
• Imprinting Related Disease: Genetic diseases related to errors in the imprinting of specific genes and chromosomal regions include Prader-Willi syndrome, Angelman syndrome, and several types of cancer.

DOWNLOAD PDF