Apoptosis and Its Role in Physiology

IOSR Journal of Pharmacy and Biological Sciences, 2014

Apoptosis is the process of programmed cell death (PCD) which usually occurs in multicellular organisms. In this case, biochemical events leads to morphological cell changes and death. Some of these changes are blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation and chromosomal Deoxyribonucleic Acid (DNA) fragmentation. Apoptosis is however distinct from necrosis which is a form of traumatic cell death that results from acute cellular injury. Apoptosis generally confers advantages during an organism's life cycle. One of the advantages can be seen in the differentiation of fingers and toes in a developing human embryo. This occurs because cells between the fingers apoptose and causes the digits to be separate. Unlike necrosis, apoptosis produces cell fragments called apoptotic bodies that phagocytic cells are able to engulf and quickly remove before the contents of the cell can spill out onto surrounding cells and cause damage. Also, between 50 and 70 billion cells die each day due to apoptosis in the average human adult. For an average child between the ages of 8 and 14, approximately 20 billion to 30 billion cells die a day.. In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in an extensive variety of diseases whereby excessive apoptosis causes atrophy and an insufficient apoptosis results in uncontrolled cell proliferation leading to cancer or tumour

World Journal of Pharmaceutical Research

The process of apoptosis or programmed cell death is characterized by distinct morphological characteristics and energy-dependent biochemical mechanisms. It is an intrinsic cell-suicide programme which ensures proper development by maintaining tissue homeostasis and safeguarding the organism by getting rid of damaged or infected cells that may interfere with normal function. Apoptosis is a vital component of various processes including normal cell turnover, hormone-dependent atrophy, proper development and functioning of the immune system, chemical-induced cell death and embryonic development. Dysregulation of apoptotic signalling and inappropriate apoptosis (either too little or too much) is a factor in many diseases including neurodegenerative diseases, autoimmune disorders and many types of cancer. The ability to modulate the life or death of a cell is recognized for its immense therapeutic potential. Therefore, research continues to focus on the elucidation and analysis of the c...

The American Journal of Medicine, 1999

Pathology - Research and Practice, 1996

In all normal tissues, cell proliferation and cell death are balanced. The physiology of normal cell death, which has become generally known as apoptosis or programmed cell death, has been intensely investigated in recent years. In this review the cell biology and biochemistry of apoptosis are discussed. Although apoptotic cells can be morphologically recognized, characteristic molecular features such as internucleosomal DNA fragmentation, and histochemical techniques such as in situ end labeling, facilitate the recognition of apoptosis. Many of the genes involved in the regulation of apoptosis, which include cell growth associated genes such as c-myc and p53, have been identified. It has become clear that the bcl-genes (more explicitly bcl-2 and bax) are important apoptosis regulators. The details of the mechanism of programmed cell death are, however, not completely unraveled.

2005

The fact that cell death is not ultimately a bad thing came as a surprise to many researchers. Physiological cell death has been observed in various multicellular organisms. Apoptosis or programmed cell death is the predominant form of physiological cell death by which the organism eliminates unnecessary or damaged single cells. It is a major component of normal development and disease. Apoptosis is characterized by membrane blebbing, shrinkage of the cell, nuclear fragmentation and chromatin condensation. Organelles are preserved almost intact. Cell surface molecules change to assure that apoptotic cells will be immediately recognized and engulfed by neighboring cells or phagocytes leading to little or no inflammation. A wide variety of physiological and pathological stimuli can initiate apoptosis. They act via receptor mechanisms, through biochemical agents, or cause DNA and cell membrane damage. Death receptors that initiate apoptosis include the Fas receptor and the TNF receptor systems. After an appropriate stimulus, the first stage of apoptosis or "decision phase" is the genetic control point of cell death. This is followed by the second stage or "execution phase", which is responsible for the morphological change in apoptosis. The third stage is engulfment of the dying cell followed by degradation of the engulfed cell DNA. There are two overlapping signaling pathways leading to apoptosis, termed the intrinsic and extrinsic pathways. In the intrinsic, various stimuli, such as oxidative stress, lead to mitochondrial dysfunction and the release of pro-apoptotic factors. Ligand binding to cell surface death receptors, such as Fas, activates the extrinsic pathway. During the last decades the molecular mechanisms involved in disordered apoptosis were unraveled, suggesting that cancer, chronic disease, and fetal developmental abnormalities can occur as a result of disordered apoptosis.

This book looks at the latest research studies on apoptosis in medicine. It is divided into three sections for convenient and easy reading. The first section which comprises two chapters is an introduction of the subject of apoptosis to the uninitiated. The second section which comprises a single solitary chapter looks at apoptosis in normal physiology during bone resorption under mechanical stress. The third and the final section reviews apoptosis in a number of pathological conditions with an emphasis on cancer.

Journal of Biology, Pharmacy and Allied Sciences, 2023

Apoptosis, programmed cell death, is an energy-dependent biochemical process which alters the cellular morphology that leads to death of cell. Apoptosis plays a major role in various cellular processes like proper functioning and development of the immune system, normal cellular turnover, hormone-induced atrophy, embryonic stage of development and chemicaltriggered cell death. Disproportionate apoptosis either more or less is a major factor for illness in many human beings including autoimmune diseases, neurodegenerative disorders, ischemic damage, and different types of cancer. The potential to stabilize the life or death of a cell is an index for its intense therapeutic property. Therefore, various signaling pathways and cell cycle machinery are the research area to focus on the control of cell cycle arrest and apoptosis. The research in the field of apoptosis moving forward at very rapid rate. Presently many key proteins are identified which are responsible for apoptosis but the mechanisms of action of these proteins are still to be elucidated. The aim of this review is to provide current knowledge in the field of apoptosis which includes the role of apoptosis in relation to health and various disease states, detection methods, and a potential alternative forms of apoptosis.

Journal of Orofacial Sciences, 2012

Cell death is one of the essential processes. Balance between cell division and cell death is of utmost importance for the development and maintenance of multi-cellular organism. Disorders of either process have pathologic consequences and can lead to disturbed embryogenesis, neurodegerative diseases, or the development of cancers. This article reviews the apoptotic as well as anti-apoptotic molecules along with molecular pathways, which may alter in many diseases.

Journal of Research and Practice in Dentistry, 2014

Apoptosis is considered as a tightly regulated active process signified by specific morphological and biochemical. On contrary to apoptosis, necrosis is a passive, energy independent pathologic process. The significance of understanding the apoptosis cascade mechanism is imperative as apoptosis being component of both physiological and pathological process. Apoptosis can be stimulated by both physiological and pathological conditions and hence play a role in maintenance of normal homeostasis and in pathogenesis of several diseases. Signaling for apoptosis occurs via caspase dependent and independent pathways that are initiated either from triggering events within the cell or from outside the cell by ligation of death receptors. Present review aims to provide an overview regarding apoptosis, its morphological and biochemical characterstics, its mechanism and its implication in health and diseases.

Archives of Surgery, 1998

urrently there is much interest and excitement in the understanding of how cells undergo the process of apoptosis or programmed cell death. Understanding how, why, and when cells are instructed to die may provide insight into the aging process, autoimmune syndromes, degenerative diseases, and malignant transformation. This review focuses on the development of apoptosis and describes the process of programmed cell death, some of the factors that incite or prevent its occurrence, and finally some of the diseases in which it may play a role. The hope is that in the not too distant future we may be able to modify or thwart the apoptotic process for therapeutic benefit.