Endogenous Retroviruses - Epigenetic Immunity without Darwin

The paper "Emerging roles for endogenous retroviruses in immune epigenetic regulation" by Carmen A. Buttler and Edward B. Chuong reviews the latest research on the role of endogenous retroviruses (ERVs) in regulating the immune system epigenetically. ERVs are viruses that have integrated their DNA into the germline of their hosts and are passed down to subsequent generations. While most ERVs are inactive, some have been co-opted by the host genome to play important roles in cellular function, including immune regulation.

Epigenetic regulation is the process by which gene expression is controlled without changing the underlying DNA sequence. This is done through modifications to the DNA itself, such as DNA methylation and histone modification, or by non-coding RNAs. ERVs can influence epigenetic regulation in a number of ways, including:

• Providing regulatory elements: ERV-derived sequences can act as promoters, enhancers, and silencers to regulate the expression of nearby genes. For example, the ERV-derived LTR promoter is used to drive the expression of many important immune genes, such as those encoding interferons and cytokines.

• Encoding regulatory proteins: Some ERVs encode proteins that can directly regulate gene expression. For example, the ERV-encoded protein Syncytin-1 interacts with histone deacetylases to repress the transcription of certain genes.

• Modulating DNA methylation: ERVs can also influence DNA methylation, which is a key epigenetic mark that regulates gene expression. For example, the ERV-encoded protein Gag can recruit DNA methyltransferases to specific genes, leading to their silencing.

The authors of the review discuss a number of examples of how ERVs contribute to immune regulation. For example, ERVs are involved in the development and function of dendritic cells, macrophages, and natural killer cells. ERVs also play a role in the innate immune response, such as by regulating the production of interferons and other antiviral cytokines.

In addition to their role in normal immune function, ERVs have also been implicated in a number of autoimmune diseases, such as systemic lupus erythematosus (SLE) and multiple sclerosis (MS). In these diseases, ERVs are thought to be inappropriately activated, leading to the production of autoantibodies and inflammation.

The authors of the review conclude by discussing the potential implications of ERV-mediated immune regulation for the development of new therapies for autoimmune diseases and other immune disorders. For example, targeting ERV-derived regulatory elements or proteins could be a way to suppress unwanted inflammation or boost the immune system to fight infection.

Overall, this review provides a comprehensive and up-to-date overview of the emerging role of ERVs in immune epigenetic regulation. The authors highlight the importance of ERVs in normal immune function and their potential role in the development of autoimmune diseases.

The implications of the paper challenges neo darwinism in several ways.

First, ERVs are not simply parasitic elements (Junk DNA) that have no benefit to the host. Instead, they have been incorporated into the host genome over millions of years and play important roles in immune function. This suggests that evolution is not simply a process of random mutation and selection, but that there is also a role for cooperation and coevolution between different species.

Second, ERVs can regulate the expression of immune genes through epigenetic mechanisms, such as DNA methylation and histone modification. This suggests that epigenetics plays a more important role in evolution than previously thought. Neo Darwinism traditionally focuses on genetic changes, but epigenetic changes can also be inherited and can have a significant impact on gene expression.

Third, ERVs are thought to be involved in the development of autoimmune diseases, such as systemic lupus erythematosus (SLE). This suggests that ERVs can have a negative impact on host fitness, which is not consistent with the neo darwinian view of evolution as a process that always leads to increased fitness.

Overall, the emerging role of ERVs in immune epigenetic regulation challenges neo darwinism by suggesting that evolution is a more complex process than previously thought, that epigenetics plays an important role in evolution, and that ERVs can have a negative impact on host fitness.

Here are some specific examples of how ERVs challenge neo darwinism:

• ERVs have been shown to play a role in the development of the placenta, which is a complex organ that is essential for successful reproduction. This suggests that ERVs can be beneficial to the host, even though they are of viral origin.

• ERVs have also been shown to regulate the expression of immune genes in response to infection. This suggests that ERVs can help the host to defend itself against pathogens.

• However, ERVs have also been implicated in the development of autoimmune diseases, such as SLE. This suggests that ERVs can also be harmful to the host.

These findings suggest that the relationship between ERVs and their hosts is complex and nuanced. ERVs can be both beneficial and harmful, and they can play important roles in both evolution and disease.

Neo Darwinism is still a widely accepted theory of evolution. However, the emerging role of ERVs in immune epigenetic regulation suggests that neo-darwinism needs to be updated or replaced to take into account the latest scientific discoveries.