Molecular Biology and Epigenetic Modifications Definition Publisher



F Khatami FATEMEH ; Ra Arabzadeh Bahri Razman ARABAZADEH ; H Sharifkazemi HOSSEIN ; Sm Sajadi Seyed MOHAMMAD ; A Shamshirgaran AMIRREZA ; F Le Calvezkelm FLORENCE
Source: Published:2024

Abstract

Epigenetics refers to cellular and physiological changes that do not arise from alterations in DNA sequence. It primarily involves the study of external or environmental factors that regulate the activation or silencing of genes, thereby affecting how genes are read. Epigenetic mechanisms are sensitive to environmental effects and are key contributors to the formation of phenotypes (1). Consequently, epigenetic research aims to elucidate dynamic variations in cell transcription potential. While the use of the term “epi” to describe processes that are not heritable is a matter of debate, these variations may or may not be inheritable. Unlike genetics, which is based on changes in DNA sequence (genotype), changes in gene expression or cellular phenotype in epigenetics have different reasons. For this reason, the prefix “epi,” derived from the Greek επί- meaning above, beyond, or around, is used. Examples of mechanisms creating these changes include DNA methylation and histone modifications, each altering gene expression without being responsible for changes in DNA sequence. Gene expression is controlled by the activity of suppressor proteins that bind to silencing regions of DNA. These epigenetic changes may persist throughout cell division, the lifespan of a cell, and possibly across multiple generations, although no alteration in DNA sequence is observed. Instead, nongenetic factors cause genes in an organism to exhibit different behaviors or expressions. An example of an epigenetic change in eukaryotes is the process of cell differentiation. During morphogenesis, pluripotent stem cells derived from the embryonic germ layers transform into fully differentiated cell types. This involves the continued division of zygote-derived cells into various cell types, such as neurons, muscles, epithelial tissues (epithelium), vascular tissues (endothelium), blood vessels, and more. Consequently, the activation of certain genes and the suppression of others lead to the creation of diverse cell types. The theory of epigenetics encompasses the development of genetic behavior as well as the direct impact of environmental forces on gene expression. This theory focuses on the dynamic interaction between these two capabilities. Throughout the 19th and 20th centuries, the most influential ideas on development under various names and subcategories have been discussed. One initial concept in embryology proposed by Carl Ernst von Baer and extended by Ernst Haeckel laid the foundation. Another distinctive approach, known as “Baldwin evolution” by James Mark Baldwin, has become prominent today (2). A different perspective, foundational epigenetics (physiological biology), was developed by Paul Wintrebert. Another type of probabilistic epigenesis was presented by Gilbert Gottlieb in 2003 (3). “Probabilistic epigenesis” is a perspective that suggests a bidirectional, four-level analysis-based influence on the development of an organism. These four levels of analysis include environmental factors (social, physical, and cultural), behavior, neural factors, and genetic activity. This approach involves examining all possible factors influencing the development of an organism, not only how organisms affect each other but also how organisms influence their own development. Considering developmental psychology, Erik Erikson developed the concept of epigenetic principle. This principle states how we have developed our personality through the predetermined stages and are influenced by the surrounding environment and culture (4). This biological unfolding occurs through social and cultural regulations during psychological growth stages, determining “success or failure in each stage.” The epigenetic theory considers evolutionary trends because of a reciprocal interaction between the environment and inheritance. The scope of environmental effects includes aspects acquired through upbringing, such as parental influences, family dynamics, education, neighborhood quality, exposure to viruses, and intracellular events. Additionally, the cultural dimensions’ theory suggests that different cultures lead to different environmental influences. Since the epigenetic theory is grounded in the environment (which varies among different cultures) and heredity (as a factor influencing development), it can predict where and how individuals may grow. Socioeconomic status can aid environmental effects, for example, facilitating positive development through access to healthy food, medication, and care. Genes produce proteins throughout an individual’s lifespan, and these proteins can differ in various environments (5). However, the epigenetic theory states that common genes do not independently determine individual traits; instead, traits are environment-dependent, with no consensus on what percentage of our nature or nurture contributes to our existence. © 2024 Elsevier B.V., All rights reserved.