Antibody News

The inflammatory response consists of a complex network of signaling pathways that regulate a diverse set of cytokines, growth factors, adhesion molecules, and transcription factors (1). Of the proinflammatory signaling pathways the NF-kB family is particularly well studied for its role in apoptosis, cancer, and the development and maintenance of the immune system (1). The family consists of the transcription factors p50, p52, RelA (p65), RelB, and c-Rel. Each of these share the Rel homology domain (RHD) that is responsible for dimerization and DNA binding (2). Under normal conditions NF-kB exists as a cytoplasmic dimer in an inactive state associated with the IkB proteins (2). Stimuli, such as a microbial infection, activate TNF receptor or Toll-like receptors to activate the IkB kinase complex leading to the ubiquitination...

Histones make up the main protein component of chromatin and are responsible for storing and organizing the genome in a compact yet accessible manner. In addition to storage, histones play an important role in the regulation of various cellular processes such as DNA replication, transcription, and mitosis by regulating the accessibility of DNA to various DNA-binding proteins. Simply put, chromatin exists in “open” and “closed” states. Chromatin in its closed state is inaccessible to DNA-binding proteins like transcription factors while open chromatin is accessible to DNA replication and RNA transcription machinery. Transitions between open and closed chromatin states are carried out through the eviction of nucleosomes or by altering DNA-histone interactions through the post-translational modification of histone proteins. These reactions are carried out by chromatin remodeling complexes. Histone H4 is one of the core structural histones that...

Histones are nuclear proteins essential for the storage and organization of genomic DNA as chromatin. Chromatin consists of DNA wrapped tightly around histone oligomers to form nucleosomes. In addition to compacting the genome, histones also regulate the accessibility of the DNA to the transcription and replication machinery to influence gene expression and mitosis. In addition to the core histones H1, H2A, H2B, H3, and H4, there are histone variants with specific functions in gene expression, development, and DNA repair. One of the variants is HIST3H3, also known as H3.1t or H3t. The H3.1t protein is primarily expressed in the testis leading researchers to believe its main function is in DNA storage and compaction during spermatogenesis (1). Analysis of H3.1t containing nucleosomes revealed inherent instability compared to...

Histones are the main protein component of chromatin and are essential for the storage and compaction of the genome. DNA wraps around histone oligomers to make up nucleosomes, the individual subunits of chromatin. By altering the accessibility of the genome, chromatin structure is important for regulating various cellular processes including replication, transcription, and DNA repair. Typically chromatin structure is influenced by post-translational modification of histone proteins at lysine and arginine residues. These residues are concentrated at the amino-terminal end of the histone protein and can alter its interaction with the DNA or recruit and bind to chromatin remodeling complexes. The complex language of histone modifications creates multiple levels of gene regulation and also forms the basis for epigenetic regulation. Of the core histones, H2A, H2B, H3, and...

Thyroid transcription factor 1 (TTF-1), also known as NKX2.1, is a conserved master regulatory transcription factor involved in the development of the lung, brain, and thyroid (1). In the lung TTF-1 positively regulates the expression of several lung-specific proteins including thyroglobulin, thyroperoxidase, and surfactant proteins A, B, and C (1). TTF-1’s control of this transcriptional network is important for the terminal differentiation of various lung cell lineages (1). Detection of the nuclear TTF-1 through immunostaining with TTF-1 antibodies has served an important role in dissecting the protein’s function during the morphogenesis and differentiation of epithelial lung cells (2). In addition to its normal function in differentiation, TTF-1 is also...

AKT1 is a serine/threonine protein kinase with homology to protein kinase A (PKA) and protein kinase C (PKC). AKT1 contains the central kinase domain sandwiched between a pleckstrin homology domain and a regulatory domain (1). AKT1 is regulated by receptor tyrosine kinase pathways and is activated in a PI3K-dependent manner following growth factor stimulation (1). Production of PIP3 at the plasma membrane by PI3K is though to recruit AKT1 where it is then phosphorylated by 3-phosphoinositide-dependent kinase 1 (PDK1). Activated AKT1 mediates a variety of cellular processes by phosphorylating downstream substrates to affect their activity, localization, or stability (1). These cellular processes include regulation of cell metabolism, growth, survival, and cell cycle progression (1). Mutation of AKT1 and deregulation of these cellular processes can lead to various diseases such as...

Succinate dehydrogenase is an important tetrameric protein involved in the citric acid cycle. It is localized to the inner mitochondrial membrane of cells. Succinate dehydrogenase makes up Complex II of the electron transport chain (ETC) and is responsible for the conversion of succinate to fumarate. This enzymatic reaction also generates a molecule of FADH2, harnessed by the ETC to make energy for the cell. SDHA, the flavoprotein subunit of the succinate dehydrogenase tetrameric complex, interacts with SDHB, SDHC, and SDHD in the complex. SDHA oxidizes succinate by deprotonating the α-carbon and transferring the proton to the FAD cofactor to generate FADH2. SDHA has been identified as a tumor suppressor gene (1). SDHA mutations have been implicated in the pathogenesis of a neuroendocrine tumor known as a paraganglioma. Other mutations in the SDHA gene can cause dysfunction of the entire succinate dehydrogenase complex, resulting in a condition known as mitochondrial...

Actin is the widely studied and ubiquitous cytoskeletal protein capable of forming dynamic microfilament structures. These filaments are essential for diverse cellular functions including cell shape, migration, cytokinesis, and intracellular trafficking (1). Actin is present in three main isoforms: alpha, beta, and gamma. These globular actin isoforms (G-actin) assemble into dynamic filamentous polymers called F-actin. This process is highly regulated by various actin-binding proteins that affect the stability, organization, and depolymerization of F-actin (1). Given its constitutive high expression, actin is considered a housekeeping gene and easily serves as an internal reference in protein and gene expression studies. Actin transcripts are easily detected through qPCR while western blotting with actin antibodies can provide a convenient loading control. While typically high in expression, beta-actin (ACTB) is further...

Parkin/PARK2 is a cytosolic enzyme which gets recruited to cellular mitochondria damaged through depolarization, ROS or unfolded proteins accumulation, and exert protective effects by inducing mitophagy (mitochondrial autophagy). Parkin induces mitophagy by promoting mitofission (mitochondrial division) and by ubiquitinating mitochondrial proteins to facilitate their recognition/recruitment to the autophagosomal surface. It is a RING-in-between-RING (RBR) E3 ligase which is capable of mediating mono, multi-mono and polyubiquitylation of several proteins including MFN1, MFN2, Miro, BCL2, SYT11, CCNE1, GPR37, RHOT1/MIRO1, STUB1, SNCAIP, SEPT5, TOMM20, USP30, ZNF746, AIMP2 etc. Mutations in PARK2 gene are the most common cause of autosomal recessive Parkinson’s disease (1). Studies implicating PINK1−/− and Parkin−/− mutant Drosophila flies have shown similar mitochondrial abnormalities, as well as neuronal loss and motor deficits, and that Parkin can...

The Role of Caspase-3 in Apoptosis

Caspase-3 enzyme is a member of the family of endoproteases which regulate inflammation and apoptosis signaling networks. Caspase-3 is known as an executioner caspase in apoptosis because of its role in coordinating the destruction of cellular structures such as DNA fragmentation or degradation of cytoskeletal proteins (1). The activity of caspase-3 is tightly regulated and it is produced as zymogen in an inactive pro-form (1). Caspase-3 antibodies serve as excellent biomarkers to monitor induction of apoptosis by detecting the levels of pro caspase-3 and its active form. Cleavage and activation of pro caspase-3 is catalyzed by caspase-8, caspase-...

Caspase-7 is an effector caspase with important roles in mediating cell death signaling. As an effector caspase, caspase-7 is cleaved and activated by initiator caspases such as caspase-1 (1). Like other caspase family proteins, caspase-7 contains a catalytic cysteine residue in its active site. This allows caspase-7 to cleave various substrates, such as PARP, to aid in the degradation and destruction of the cell (2). Mutations in caspase-7 have been found in numerous cancers demonstrating the importance of caspase-7 mediated apoptosis in preventing tumorigenesis (1). Caspase-7 shows some functional redundancy with caspase-3 as both they share a number of the same substrates. However both of these effector caspases have distinct functions during apoptosis. Recent studies have indicated caspase-3 is needed for efficient cell killing and can also block ROS production (3). Caspase-7, on the...

Succinate dehydrogenase (SDH) is a highly conserved protein complex located on the inner mitochondrial membrane where it functions during the Krebs cycle by oxidizing succinate to fumarate (1). This reaction is also important for feeding electrons into the electron transport chain. SDH complex contains four subunits: SDH-A, -B, -C, and -D. Mutation of SDH-A often leads to mitochondrial encephalopathy while mutations to subunits B, C, and D lead to tumors of the head and neck (1).

Belinsky et al. performed immunohistochemistry using SDHA antibody to identify SDH complex deficiency in patient samples and found that bi-allelic inactivation of SDHA is common in gastrointestinal stromal tumors (2). Following staining with the SDHA antibody, samples were sequenced and verified to contain various inactivating mutations. This SDHA antibody based method of...