Chromatin condensation is a key hallmark of apoptosis, representing a critical morphological change during the process of programmed cell death. During apoptosis, the chromatin, which is normally loosely distributed within the nucleus, undergoes a dramatic condensation and segregation, resulting in the formation of densely packed, crescent-shaped masses against the nuclear envelope. This condensation is not only a diagnostic feature of apoptosis but also plays functional roles in the orderly disassembly of the cell.
The process of chromatin condensation in apoptosis is tightly regulated by a variety of proteins and signaling pathways that modify the structure and interaction of chromatin components. Histones, the core proteins around which DNA is wound, undergo specific post-translational modifications, such as phosphorylation and acetylation, which alter their interaction with DNA and other nuclear proteins. For instance, during apoptosis, the phosphorylation of histone H2B is associated with chromatin condensation. Additionally, the cleavage of nuclear proteins like lamin by caspases also contributes to chromatin condensation and nuclear fragmentation. Lamins form a mesh-like structure underlying the nuclear envelope, and their cleavage helps dismantle the nuclear structure, facilitating further condensation and eventual fragmentation.
Key to the process of chromatin condensation is the role of specific enzymes, including poly(ADP-ribose) polymerase (PARP) and the DNA repair machinery. PARP, which normally functions in DNA repair, can be cleaved and inactivated by caspases during apoptosis. The inactivation of PARP prevents the repair and ligation of DNA breaks, which are abundantly generated as the chromatin condenses. Moreover, the endonucleases activated during apoptosis, such as CAD (caspase-activated DNase), play direct roles by fragmenting DNA at internucleosomal regions, a step that not only contributes to condensation but also to the generation of the characteristic 'DNA ladder' seen during late apoptosis.
Chromatin condensation is not merely a byproduct of apoptosis but serves several purposes: it prevents the leakage of potentially harmful DNA and chromatin content into surrounding cells and tissues, thereby containing the damage and aiding in the phagocytic recognition and removal of apoptotic cells. This containment is crucial for preventing inflammation and autoimmune responses against nuclear components released from dying cells.
Figure 1 Chromatin condensation and cancer cell transmigration. (Fu, 2012)
AIF, or Apoptosis-Inducing Factor, is a mitochondrial flavoprotein that plays a significant role in both caspase-dependent and caspase-independent pathways of apoptosis. Initially characterized for its role in the mitochondrial pathway of programmed cell death, AIF is primarily located in the mitochondrial intermembrane space under normal conditions. Upon apoptotic stimulation, such as extensive oxidative stress or DNA damage, AIF is released from the mitochondria into the cytosol and subsequently translocates to the nucleus. In the nucleus, AIF binds to DNA and induces chromatin condensation and large-scale DNA fragmentation, which are hallmark features of caspase-independent apoptosis. This mode of action distinguishes AIF from other apoptotic factors that rely on caspase activation. Beyond its role in apoptosis, AIF also functions in maintaining mitochondrial structure and function, playing a role in oxidative phosphorylation and regulating redox metabolism. This non-apoptotic role is crucial for cell survival and normal cellular function, highlighting the dual functionality of AIF within the cell. The involvement of AIF in apoptosis and cell metabolism makes it a critical player in various pathological conditions, including neurodegenerative diseases, myocardial infarction, and stroke. In these diseases, excessive activation of AIF-mediated apoptosis contributes to cell loss and tissue damage. Conversely, AIF deficiency can lead to mitochondrial dysfunction and contribute to developmental abnormalities and degenerative diseases.
AIFM1, also known as apoptosis-inducing factor mitochondria-associated 1, plays pivotal roles in regulating cell processes and influencing disease progression within the intricate landscape of cellular biology. Positioned primarily within the inner mitochondrial membrane, AIFM1 orchestrates diverse functions essential for cell survival and death. Its primary function as a mitochondrial oxidoreductase underscores its significance in electron transport chain (ETC) activities, facilitating ATP synthesis and maintaining cellular energy homeostasis. Beyond energy metabolism, AIFM1 assumes a multifaceted role in apoptosis, serving as a key mediator of caspase-independent cell death pathways. Upon apoptotic stimuli, AIFM1 translocates from mitochondria to the nucleus, where it induces chromatin condensation and DNA fragmentation, culminating in cell demise. Additionally, emerging evidence implicates AIFM1 in other cellular processes, including mitochondrial dynamics, redox signaling, and cellular differentiation, highlighting its pleiotropic functions. Dysregulation of AIFM1 has been intricately linked to various pathological conditions, ranging from neurodegenerative disorders to cancer. In neurodegeneration, aberrant AIFM1 activity contributes to mitochondrial dysfunction, oxidative stress, and neuronal demise, exacerbating conditions such as Alzheimer's and Parkinson's diseases. Similarly, in cancer, AIFM1 modulation influences tumor growth, metastasis, and response to therapy, underscoring its potential as a therapeutic target.
The Dynamic Filament Formation of Actin (DFFA) constitutes a multifaceted molecular machinery essential for the maintenance of cellular architecture, dynamics, and function. Serving as a cornerstone of the cytoskeleton, DFFA orchestrates a myriad of cellular processes crucial for cell survival and function. Notably, DFFA's role in regulating actin polymerization dynamics is central to its function. By modulating the assembly and disassembly of actin filaments, DFFA controls diverse cellular events, including cell shape changes, migration, and division. Moreover, DFFA actively participates in intracellular transport mechanisms, facilitating the movement of organelles and vesicles along the cytoskeletal network. Beyond its structural functions, DFFA serves as a signaling hub, integrating extracellular cues with intracellular responses to regulate gene expression, cell proliferation, and differentiation. This multifaceted functionality positions DFFA as a critical player in cellular homeostasis. However, perturbations in DFFA dynamics have been implicated in various disease states. Dysregulated DFFA activity is associated with aberrant cytoskeletal organization, impaired cell motility, and disrupted cellular signaling pathways, all of which contribute to disease progression. In cancer, for instance, alterations in DFFA expression and activity are frequently observed and correlate with increased tumor invasiveness and metastatic potential. Similarly, in neurodegenerative disorders such as Alzheimer's disease, abnormalities in DFFA-mediated cytoskeletal dynamics contribute to synaptic dysfunction and neuronal degeneration. Moreover, cardiovascular diseases like cardiomyopathies are characterized by disrupted DFFA-dependent contractile function in cardiac muscle cells.
Biomarker | Alternative Names | Gene ID | UniProt ID | Roles |
AIF | AIF; Acidic isoferritin | Compared with ferritin of normal liver tissue, fetal and tumor tissues show a higher proportion of ferritin fragments with lower pH value, which is called acidic isoferritin (AIF). AIF has been studied as a tumor associated-antigen for its potential clinical value, and monoclonal antibodies against AIF have been developed for the serum AIF detection and tumor localization. | ||
AIFM1 | AIF; CMT2D; CMTX4; COWCK; COXPD6; NADMR; NAMSD; PDCD8; DFNX5; apoptosis inducing factor; mitochondria associated 1; apoptosis inducing factor mitochondria associated 1; AUNX1; SEMDHL | 9131 | O95831 | This gene encodes a flavoprotein essential for nuclear disassembly in apoptotic cells, and it is found in the mitochondrial intermembrane space in healthy cells. Induction of apoptosis results in the translocation of this protein to the nucleus where it affects chromosome condensation and fragmentation. In addition, this gene product induces mitochondria to release the apoptogenic proteins cytochrome c and caspase-9. Mutations in this gene cause combined oxidative phosphorylation deficiency 6 (COXPD6), a severe mitochondrial encephalomyopathy, as well as Cowchock syndrome, also known as X-linked recessive Charcot-Marie-Tooth disease-4 (CMTX-4), a disorder resulting in neuropathy, and axonal and motor-sensory defects with deafness and cognitive disability. Alternative splicing results in multiple transcript variants. A related pseudogene has been identified on chromosome 10. |
DFFA | DNA Fragmentation Factor Subunit Alpha; DNA Fragmentation Factor, 45kDa, Alpha Polypeptide; DNA Fragmentation Factor 45 KDa Subunit; Inhibitor Of CAD; DFF-45; DFF45 | 1676 | O00273 | Apoptosis is a cell death process that removes toxic and/or useless cells during mammalian development. The apoptotic process is accompanied by shrinkage and fragmentation of the cells and nuclei and degradation of the chromosomal DNA into nucleosomal units. DNA fragmentation factor (DFF) is a heterodimeric protein of 40-kD (DFFB) and 45-kD (DFFA) subunits. DFFA is the substrate for caspase-3 and triggers DNA fragmentation during apoptosis. DFF becomes activated when DFFA is cleaved by caspase-3. The cleaved fragments of DFFA dissociate from DFFB, the active component of DFF. DFFB has been found to trigger both DNA fragmentation and chromatin condensation during apoptosis. Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. |
CAT | Product Name | Biomarker | Assay | Image |
ZG-0267F | Mouse Anti-AIFM1 Recombinant Antibody (ZG-0267F) | AIFM1 | WB | |
ZG-0537J | Rabbit Anti-AIFM1 Recombinant Antibody (clone 4B2) | AIFM1 | WB |
For research use only. Not intended for any clinical use.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.