Selective Oxidation Of 5-Methylcytosine By Tet-Family Proteins
Patent No. US12291742 (titled "Selective Oxidation Of 5-Methylcytosine By Tet-Family Proteins") was filed by The United States Of America As Represented By The Secretary Department Of Health And Human Services on Feb 27, 2024.
What is this patent about?
’742 is related to the field of epigenetics , specifically to methods for regulating and detecting the methylation status of DNA. DNA methylation, particularly at cytosine bases, plays a crucial role in gene expression, genomic stability, and development. Aberrant methylation patterns are implicated in diseases like cancer, making the ability to manipulate and analyze DNA methylation a key area of research.
The underlying idea behind ’742 is that TET enzymes , a family of dioxygenases, can convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) by hydroxylation. This conversion is a key step in DNA demethylation, potentially leading to altered gene expression. The insight is that by controlling the activity of TET enzymes, one can influence the epigenetic landscape of a cell.
The claims of ’742 focus on enzymatically converting 5-methylcytosine to an oxidized derivative using a TET polypeptide or a catalytically active fragment thereof. Claim 1 further specifies converting cytosine to uracil and then sequencing the nucleic acid. Claim 21 focuses on converting *all* 5-methylcytosine to an oxidized derivative.
In practice, the invention involves using purified TET enzymes or their active fragments to modify DNA *in vitro* or *in vivo*. This enzymatic modification can then be followed by bisulfite sequencing, which, while not differentiating between 5mC and 5hmC, can reveal the overall level of modified cytosines. The invention also encompasses methods for detecting the resulting 5hmC, for example, using antibodies.
’742 differentiates itself from prior approaches by leveraging the specific enzymatic activity of TET proteins. Previous methods for demethylation were less targeted or relied on passive mechanisms. By using TET enzymes, the invention provides a more direct and potentially controllable way to alter DNA methylation patterns, offering new possibilities for research and therapeutic applications in areas like stem cell reprogramming and cancer therapy.
How does this patent fit in bigger picture?
Technical landscape at the time
In the late 2000s when ’742 was filed, DNA methylation and demethylation were recognized as critical processes in mammalian development and tumorigenesis, at a time when techniques such as bisulfite sequencing were commonly used to study DNA methylation patterns. However, the molecular mechanisms of active DNA demethylation were not fully understood, and the enzymes involved had not been definitively identified. Assays for detecting and quantifying DNA methylation typically relied on methods that could not distinguish between different forms of modified cytosine.
Novelty and Inventive Step
The examiner approved the amended and new claims because they were considered novel and non-obvious over the prior art. The claims were also deemed enabled by the original disclosure. A terminal disclaimer was filed to prevent the patent from extending beyond the expiration date of related patents and co-pending applications.
Claims
This patent contains 30 claims, with independent claims 1 and 21. The independent claims focus on methods involving contacting a nucleic acid molecule with an enzyme to convert 5-methylcytosine to an oxidized derivative, and then converting cytosine to uracil, followed by sequencing. The dependent claims generally specify details and limitations to the independent claims, such as the amount and type of enzyme, the nucleic acid source, and the addition of a sugar residue.
Key Claim Terms New
Definitions of key terms used in the patent claims.
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US12291742
- Application Number
- US18588987
- Filing Date
- Feb 27, 2024
- Status
- Granted
- Expiry Date
- Sep 28, 2029
- External Links
- Slate, USPTO, Google Patents