What is Senescence?
Senescence is a process in which there is a continuous growth arrest of cells without cell death when the entire process of cell division stops.
It can be at the cellular level or the aging of the whole organism.
It is characterized by a gradual decline in specific functions in organ systems, leading to progressive degeneration and eventual organ failure.
As cells age, they enter the senescence phase. They do not support or divide tissues, but produce chemicals that have the ability to encourage neighboring cells to enter senescence.
They pose risks because they can cause cancer, damage organs and impair their function, increase chronic inflammation and more.
Senescent cells destroy themselves through a process called apoptosis which causes them to be eliminated by the immune system.
However, with age, our immune systems will become weaker and unable to eliminate all these senescent cells that accumulate over time so senescent cells are key to the progression of aging because they cause inflammation and destruction of surrounding tissues.
Senescent cells release proinflammatory chemokines, cytokines, and matrix proteases resulting in the formation of SASP (Senescence-associated secretory phenotype).
SASP can contribute to cancer and the aging process, therefore, the use of senolytics is a proposed strategy to prevent aging. Senolytics are a class of drugs that focus on destroying senescent cells that appear to be resistant to apoptosis.
Removing as much as 30% of senescent cells has been shown to slow the rate of aging. Clearing senescent cells improves chronic cholesterol and various aspects of vascular aging.
Senolytics have also reduced deaths from heart disease and are used to treat cardiovascular disease, type 2 diabetes and osteoporosis.
Causes Of Senescence
Cellular aging or proliferation occurs in various cell types, such as: melanocytes, endothelial cells, epithelial cells, glial cells (nervous tissue), stem cells, adrenocortical cells and lymphocytes. Below are some of the causes.
One of the main causes of cellular aging is telomere shortening. Let’s look at a bunch of sequences at the end of each chromosome, these are telomeres. It consists of repeated nucleotide DNA, which prevents chromosomes from losing vital reproductive information. It also prevents fusion with surrounding chromosomes.
Telomeres lose a small amount of DNA with each replication because the enzymes that provide the replication process cannot reach the end of the chromosome.
Therefore, important genetic information is lost due to the loss of telomeres due to chromosome shortening, after each replication. This is the point where cells enter DDR (DNA Damage Response) mode and cannot divide. This is the state of aging.
This is because aging is a natural process and the tendency of cells to enter the senescent state is natural and definite.
Cellular aging can be induced by DNA damage in several other ways, most notably DNA double-strand breaks. This allows the cells to enter a DNA damage repair mode that ultimately leads to cellular aging.
Cells can enter the DDR state with the presence of mitogenic signals, errors in proteins that promote cell growth, and reactive oxygen species.
A number of other factors can cause aging, such as oncogene activation, radiation, cell culture, and stress on mitochondrial homeostasis. Excess mitochondrial ROS has been found to initiate cellular senescence.
Imbalances in mitochondrial homeostasis include impaired mitochondrial metabolism, electron chain transport defects, uncontrolled ROS production, increased protein kinase activity, reduced metabolic turnover, and mitochondrial calcium accumulation.
Effects Of Senescence
Aging affects the development of wrinkles, which can be attributed to the age factor, because it can cause wrinkles in older, younger things, aging helps prevent wrinkles.
Another effect is tissue repair because aging releases different types of molecules, some of which regulate growth, wound healing and signal foreign bodies to the immune system to eliminate them thus aging cells are important for tissue repair physiology and the development of symptomatic drugs to identify and repair. damaged fabrics. Senescent autonomous cells have no signaling capacity except for surrounding immune cells.
Senescent cells are the product of multiple processes and contribute to the functional decline of aging tissues. This gives the affected areas a larger area of decay, making them more susceptible to future events.
Senescence in Plants
Like all other living things, plants have different life cycles in which they grow, develop and eventually die. Before they die, they go through a number of processes of decay, ending their working life.
These processes are known as aging. Sterility-induced death of a plant or plant tissue is known as programmed cell death.
Senescence is not limited to the whole plant, but to certain parts of the plant such as leaves and flowers