Apoptosis

CD14 is a well-characterized cell-activating receptor for lipopolysaccharide-binding protein (LBP) and peptidoglycan. It is an important modulator for lipopolysaccharide (LPS)-dependent signaling and is a component of the multi-protein complex containing also containing MD2 and toll-like receptor 4 (TLR4). CD14 is an important component of the innate immune response preferentially expressed on mature cells of monocyte lineage. The CD14 protein contains eleven leucine-rich repeats (LRRs).

MUL1 is an E3 ubiquitin-protein ligase with a RING finger domain that controls mitochondrial morphology, fragmentation and localization. E3 ubiquitin ligases accept the component ubiquitin from a donor E2 ubiquitin-conjugating directly transfer this ubiquitin to designated targeted substrates. The largest, proteome-wide and site-specific quantitative mapping dataset assessment of endogenous putative ubiquitylation sites and regulation was executed by Wagner’s group in Denmark¹.

Bone morphogenetic proteins such as GDF15 belong to the transforming growth factor-beta (TGFB) family that directs tissue differentiation and maintenance. GDF15 appears to be involved in a variety of physiological processes such as pregnancy, injury and inflammation, and apoptosis. Evidence suggests GDF15 is a marker for metastasis.

The NALP family consists of cytoplasmic proteins within the larger CATERPILLER protein family. There exist in short forms (such as NALP4) and long forms (NALP1). NALP proteins include the apoptosis regulator apoptotic protease activating factor 1 (APAF1) and mammalian NOD-LRR proteins, and are thought to play a role in the inflammation and reproduction processes.

Also known as OPG, TR1 and OCIF, this gene encodes Osteoprotegerin, a heparin-binding secretory glycoprotein that belongs to the TNF-receptor superfamily. The TNFR superfamily consists primarily of transmembrane proteins that elicit signal transduction in a variety of cells and are known to mediate diverse biological responses, including cytotoxicity and apoptosis, Osteoprotegerin (OPG) was isolated independently by two laboratories in 1997 [1,2].

SR-B1 belongs to the CD36 scavenger receptor family and serves as a receptor for several ligands including phospholipids, cholesterol ester, lipoproteins, phosphatidylserine, and caveolae localized HDL. It is expressed in endothelial cells, macrophages, and dendritic cells. It facilitates the flux of both free and esterified cholesterol between the cell surface and extracellular donors and acceptors (HDL and to a lesser extent, apoB-containing lipoproteins and modified lipoproteins).

Caspase 6, also known as Apoptotic protease Mch-2, belongs to the peptidase C14A family. It functions as a downstream enzyme in the caspase activation cascade and is responsible for the execution of apoptosis. Its overexpression promotes programmed cell death.

Diseases associated with CASP6 include thoracic cancer and myocardial infarction.  Among its related super-pathways are DR3 Signaling and Apoptosis and the survival FAS signaling cascade.

The survivin anti-apoptotic protein is the smallest member of a large family of proteins such as X-linked IAP, c-IAP1 and 2, IAP-like protein-2, melanoma IAP, Livin, and NAIP. Survivin regulates basic physiological events such as the cell cycle, tumor progression, fetal development, and cell migration.

Glioma-associated oncogene 1 (Gli1) is a transcription factor within the DNA-binding zinc-finger protein family. The Sonic Hedgehog signaling pathway (SHH), which assists in embryonic development and maintaining stem cell populations in adults, activates the Gli1 protein. In the SHH Pathway, the hedgehog ligand binds to patched transmembrane protein receptor (PTC). PTC is an inhibitor of SMO, a protein receptor, and when the hedgehog ligand is present, SMO is not inhibited.

Isotype controls are primarily used as negative controls in flow cytometry but they can also be used for immunohistochemistry. They are used to approximate the non-specific target primary antibody binding due to protein-protein interactions, binding to Fc receptors on target cells, non-specific protein-protein interactions, and cell autofluorescence.