Sp100 nuclear antigen
Encyclopedia
Sp100 nuclear antigen is an interferon
stimulated antigen
found in the bile duct of primary biliary cirrhosis
. Histologically sp100 'dots' regions of the cell nucleus. Viral infection and mitogens affect the expression of the Sp100 autoantigen. Cells grown in the presence of interferon
s (α, β, and γ) revealed an increase both in size and number of the Sp100 protein-containing nuclear dots and increase the protein concentration.
This raises "the question whether cytokine
-mediated increase of Sp100 protein expression plays a role in induction of anti-Sp100 autoantibodies
."
) factor are localized to punctate domains in the nucleus (nuclear dots
or nuclear bodies). These domains (few to 20) were found to form a donut shaped structure when cells were starved of amino acids. In particular, depravation of cystine results in most pronounced changes. Two other proteins, PIC1/SUMO-1
, that also interact with nuclear pore
complex factors also interact with these two proteins. In addition sp100 interacts with a chromatin binding protein, HM1.
1 (HMG1) protein sequence as a domain. Both major classes of Sp100 splice variant proteins localize in part to nuclear dots/PML bodies and other nuclear domains.
Interferon
Interferons are proteins made and released by host cells in response to the presence of pathogens—such as viruses, bacteria, or parasites—or tumor cells. They allow communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors.IFNs belong to...
stimulated antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
found in the bile duct of primary biliary cirrhosis
Primary biliary cirrhosis
Primary biliary cirrhosis, often abbreviated PBC, is an autoimmune disease of the liver marked by the slow progressive destruction of the small bile ducts within the liver. When these ducts are damaged, bile builds up in the liver and over time damages the tissue. This can lead to scarring,...
. Histologically sp100 'dots' regions of the cell nucleus. Viral infection and mitogens affect the expression of the Sp100 autoantigen. Cells grown in the presence of interferon
Interferon
Interferons are proteins made and released by host cells in response to the presence of pathogens—such as viruses, bacteria, or parasites—or tumor cells. They allow communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors.IFNs belong to...
s (α, β, and γ) revealed an increase both in size and number of the Sp100 protein-containing nuclear dots and increase the protein concentration.
This raises "the question whether cytokine
Cytokine
Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
-mediated increase of Sp100 protein expression plays a role in induction of anti-Sp100 autoantibodies
Anti-sp100 antibodies
Anti-sp100 antibodies are found in association with primary biliary cirrhosis. The autoimmune target of anti-sp100 is the sp100 nuclear antigen which was identified by its association with primary biliary cirrhosis...
."
Sp100 and nuclear dots
Two proteins, sp100 and promyelocytic leukemia (PMLPromyelocytic leukemia protein
Probable transcription factor PML is a tumor suppressor protein that in humans is encoded by the PML gene.-Interactions:Promyelocytic leukemia protein has been shown to interact with Retinoic acid receptor alpha, HDAC1, Nerve Growth factor IB, SKI protein, Zinc finger and BTB domain-containing...
) factor are localized to punctate domains in the nucleus (nuclear dots
Nuclear dots
Nuclear dots are punctate structures found in the nucleus of certain cells. Nuclear bodies were first seen as prominent interchromatin structures in the nuclei of malignant or hyperstimulated animal cells...
or nuclear bodies). These domains (few to 20) were found to form a donut shaped structure when cells were starved of amino acids. In particular, depravation of cystine results in most pronounced changes. Two other proteins, PIC1/SUMO-1
Small ubiquitin-related modifier 1
Small ubiquitin-related modifier 1 is a protein that in humans is encoded by the SUMO1 gene.Most cleft genes have a sumoylation component .-Interactions:...
, that also interact with nuclear pore
Nuclear pore
Nuclear pores are large protein complexes that cross the nuclear envelope, which is the double membrane surrounding the eukaryotic cell nucleus. There are about on average 2000 nuclear pore complexes in the nuclear envelope of a vertebrate cell, but it varies depending on cell type and the stage in...
complex factors also interact with these two proteins. In addition sp100 interacts with a chromatin binding protein, HM1.
Sp100 splicoforms
Some sp100 variants contain a domain similar to two interferon-inducible nuclear phosphoproteins, suppressin and DEAF1. This defines a novel protein motif, the HNPP-box. Another class of variants has high mobility groupHigh mobility group
High-Mobility Group or HMG is a group of chromosomal proteins that help withtranscription, replication, recombination, and DNA repair.-Families:The HMG proteins are subdivided into 3 superfamilies each containing a characteristic functional domain:...
1 (HMG1) protein sequence as a domain. Both major classes of Sp100 splice variant proteins localize in part to nuclear dots/PML bodies and other nuclear domains.