Antibody News

MAPK8/JNK1 - A multifunctional kinase and drug target for cancer therapeutics

Monday, December 28, 2015 - 14:40

The c-Jun N-terminal kinase (JNK) family is a group of regulatory kinases with important functions in cell morphogenesis, inflammation, differentiation, and cell death (1). Aberrant activation of JNK family proteins in cancers has led to interest in small molecule JNK inhibitors as a therapeutic strategy (1). JNK1, also known as MAPK8, is expressed in most tissues and is involved in transduction of extracellular signals such as growth factors or cytokines though a phosphorylation cascade to elicit diverse intracellular responses (1). JNK phosphorylation substrates include p53, AP-1, c-Myc, and Bcl-2 (1). Defects in JNK signaling have been observed in inflammatory and neurodegenerative disorders (1). For example, increased JNK1 activity leads to hyperphosphorylation of tau in Alzheimer’s disease (2). A recent study reduced JNK1 activity by using heterozygous JNK1 deficient mice and...

RelA/NF-kB - A proinflammatory signaling pathway with roles in immunity and cancer

Monday, December 21, 2015 - 14:49

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...

MAPK3/ERK1 - A signal transduction pathway with roles in development and disease

Friday, December 18, 2015 - 13:24

Mitogen-activated protein kinases (MAPKs) are important signaling proteins needed to transmit and relay extracellular stimuli and to illicit intracellular responses (1). The MAPK family of proteins are serine/threonine kinases that are able to phosphorylate and activate downstream kinases in a signal cascade that regulates diverse cell responses such as gene expression, metabolism, apoptosis, and differentiation (1). Notable members of the MAPK family include ERK, JNK, and p38 (1). Misregulation of these pathways has been implicated in neurodegenerative diseases as well tumorigenesis (1). ERK1, also known as MAPK3, is one of the downstream kinases activated by receptor-tyrosine kinases such as EGFR and the Ras GTPase (2). ERK1/2 can phosphorylate hundreds of substrate proteins including transcription factors and cytoplasmic regulators (2). Additionally, increased...

H4 - Monitoring global chromatin structure through histone modifications

Wednesday, December 16, 2015 - 14:37

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...

GAPDH - A "housekeeping" gene with diverse functions in cellular homeostasis

Monday, December 14, 2015 - 12:23

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a well-known housekeeping gene with functions in glycolysis. Many biologists are familiar with the gene and use GAPDH antibodies for a loading control when performing west blots. However, this primarily cytoplasmic protein is an essential metabolic regulator and has been shown to be involved in a variety of cellular processes like DNA repair, membrane fusion, and cell death (1). Cytoplasmic GAPDH exists as a tetramer and normally mediates the formation of ATP and NADH during glycolysis (1). Under oxidative stress GAPDH can be post-translationally modified to regulate cell metabolism (1). Additionally GAPDH has been shown to interact with the cytoskeleton to influence microtubule and actin polymerization (1).

Identifying the diverse functions of GAPDH depends on the use of GAPDH antibodies to identify interacting proteins or examine...

H3.1t - A testis-specific histone variant

Wednesday, December 9, 2015 - 14:29

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...

MYC - A human oncogene with valuable laboratory applications

Monday, December 7, 2015 - 14:54

Myc is a basic helix-loop-helix zipper transcription factor that regulates a network of many hundreds of genes. Myc up-regulates the expression of many genes involved in cell growth and proliferation such as ribosome biogenesis and protein synthesis (1). While many Myc induced genes are transcribed by RNA polymerase II, tRNA and rRNA genes are also Myc targets (1). Myc is also responsible for repressing genes involved in cell-cycle arrest and cell adhesion. Genome-wide profiling of Myc binding through chromatin immunoprecipitation with Myc antibody has revealed broad association with many targets with some estimates as high as 10-15% of genomic loci (2). The ability of Myc to activate or repress such a large number of targets allows integration of environmental signals and regulation of opposing cellular pathways (1). The ability to enhance cell growth and block cell-cycle arrest makes Myc an important proto-oncogene as well. The...

H3.1 - A core histone essential for genome storage and organization

Friday, December 4, 2015 - 14:30

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...

H3.3 - A histone variant regulating gene expression and differentiation

Wednesday, December 2, 2015 - 14:36

Histones, the main protein component of chromatin, are essential for storing and organizing the genome in a compact yet accessible manner. DNA wraps tightly around histone oligomers to form nucleosomes which can store unused portions of DNA and regulate accessibility to the replication or transcription machinery. By affecting chromatin structure histones and their modifying enzymes make up a complex network with important regulatory roles in DNA replication, mitosis, and gene expression. In addition to the canonical histones 1-4, there are specialized histone variants with important regulatory functions in transcription or DNA repair for example. The histone variant H3.3 is deposited during replication independent assembly of nucleosomes and is typically enriched in active genes. Although only differing from canonical H3 by four amino acid residues, H3.3 can play important functions in gene expression and differentiation (1). These...

TTF1 / NKX2.1 - An essential regulator of lung development with implications in cancer diagnostics

Monday, November 30, 2015 - 14:35

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...

NLRP3/NALP3 - Sensing and responding to pathogen infection

Friday, November 20, 2015 - 12:57

The inflammasome is a multi protein complex that is an important component of the innate immune response. The inflammasome is able to sense and respond to pathogen infections by recognizing pathogen-associated molecular patterns and mediating the secretion of inflammatory cytokines. Of the various types of inflammasomes, NLRP3/NALP3 is unique because of the diverse range of microbes it is able to detect (1). Once assembled and activated, the NLRP3/NALP3 inflammasome mediates the caspase-1 dependent activation of into its active secreted form interleukin-1 into its active secreted form (1). Although important  for responding to pathogen infections, the NLRP3/NALP3 inflammasome is also involved in chronic inflammatory and age-related diseases such as atherosclerosis, Alzheimer's, and inflammatory bowel disease (1). Misactivation of the NLRP3/NALP3 inflammasome contributes to these diseases and may be...

AKT1 - Regulating cell growth and survival through phosphorylation

Friday, November 20, 2015 - 12:49

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...

p53 - Investigating an important tumor suppressor

Wednesday, November 18, 2015 - 14:37

p53 is a tumor suppressor that has a central role in regulating cell cycle arrest, DNA repair, and apoptosis. p53 is widely studied for its role in cancer and is mutated or altered in more than half of all cancers (1). This widespread role in tumorigenesis has made p53 one of the most highly studied proteins and a target for anti-cancer therapeutics. Normally, p53 allows cells to sense and respond to cellular stress such as DNA damage or hypoxia (2). In response to these signals, p53 is activated through post-translational modification and protein stabilization. This allows p53 to bind DNA and regulate the expression of various genes (2). p53 can control diverse transcriptional programs to regulate senescence and cell death programs as well as cellular metabolism (2). p53 integrates a variety of signals and allows cells to respond in a manner that is highly dependent on cellular context (2). In addition to its role as a transcription factor, p53 functions in the...

SDHA - oxidative enzyme in the citric acid cycle

Monday, November 16, 2015 - 14:49

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...

TGF-beta RIII - a high affinity reservoir for TGF-beta I/II ligands with therapeutic potential

Friday, November 13, 2015 - 08:42

TGF beta (transforming growth factor beta) is a superfamily of cytokines that participate in a variety of cellular processes including growth, proliferation, differentiation, and apoptosis. There are 3 classes of receptors for TGF beta cytokines and they are known as type I, II, and III. TGF beta receptor type III (TGF beta-RIII) is a high affinity receptor for TGF beta-I and TGF beta-II and binds other TGF beta ligands with lower affinities. It is a 250-300 kDa protein that can exist as a single pass transmembrane protein or in its soluble/secreted form. TGF beta-RIII does not have enzymatic activity within the TGF beta signaling pathway. Instead, it frequently coexists with TGF beta-R I and acts as a reservoir for its TGF beta ligands (1). TGF beta signaling has been implicated in many hereditary, developmental, and malignant conditions. There is little known about the exact role of TGF beta -RIII compared to its type I and type II counterparts.


ACTB - an abundant cytoskeletal component with applications for gene expression analysis

Wednesday, November 11, 2015 - 15:23

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...

AHR - A transcription factor regulating immunity and tumorigenesis

Monday, November 9, 2015 - 15:40

The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that controls the expression of a diverse set of genes. In the absence of ligand, AHR is retained in the cytoplasm. Upon ligand binding AHR translocates to the nucleus where it forms a heterodimer with aryl hydrocarbon receptor nuclear translocator (ARNT) (1). This receptor complex then recognizes AHR-response elements in target genes to regulate their transcription. AHR is well known for its ability to bind to the toxic chemical 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD is a highly toxic and carcinogenic compound that is produced as a side product during the industrial manufacturing of certain chemicals (1). The toxic effects of TCDD are mediated exclusively through binding to AHR. In addition to this role in TCDD toxicity, AHR functions during tumorigenesis and is found at elevated levels in aggressive tumors and tumor cell lines (2)....

Parkin - Role in Mitochondrial Quality Control and Parkinson's Disease

Friday, November 6, 2015 - 14:44

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...

YAP1 - a transcription co-activator and the downstream target of Hippo pathway

Wednesday, November 4, 2015 - 15:07

YAP1 (Yes-associated protein 1) is a  transcriptional co-activator which acts as a major effector of Hippo signaling pathway that regulates organ size/ tissue homeostasis and cell proliferation, and is an established oncogene (1).  Hippo signaling activation results in the phosphorylation mediated inactivation of YAP1, and restriction of YAP1’s transcriptional activity is the principal mechanism of growth and tumor suppression by Hippo pathway. Accordingly, loss of Hippo signaling by mutations or down-regulation of core pathway components is associated with cancer development, while YAP1 is reported as a potent oncogene that can promote tumorigenesis in a wide range of tissues (2).


Caspase 3, the executioner of apoptosis

Monday, November 2, 2015 - 14:49

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-9, and granzyme B to generate the active heterodimer of caspase-3 subunits (1).

Lin et al. used caspase-3 antibodies to monitor the induction of...

Caspase 10 - an initiator caspase in the extrinsic death receptor pathway

Friday, October 30, 2015 - 13:59

Apoptosis, also called programmed cell death, is an essential process in development and disease. The signaling networks that carry out apoptosis is consists of a series of endoproteases called caspases which are synthesized as inactive zymogens. Caspses are grouped into two classes: initiator caspases and effector caspases. Initiator caspases are activated by the assembly of multi-protein complexes such as the death-inducing signaling complex (DISC) (1). This complex consists of the Fas receptor and the death effector domain containing initiator caspases -8 or -10 (1). Once activated, initiator caspases cleave and activate effector caspases which then go on to cleave various substrates to aid in the destruction of the cell in an organized manner.

Caspase-10 is of particular importance given its role in apoptotic induction and implications in tumorigenesis. Examination of lung and breast carcinoma cell lines using western...

Caspase 7 - A key effector of the apoptotic pathway

Wednesday, October 28, 2015 - 14:44

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...

NOD2 - inflammatory signaling and NFkB activation

Monday, October 26, 2015 - 14:48

Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is an intracellular pattern recognition receptor (PRR) that plays an important role in recognizing bacterial pathogens and initiating an immune response. As a PRR, NOD2 recognizes bacterial lipopolysaccharide (LPS), muramyldipeptide (MDP), and other pathogen-associated molecular patterns (PAMPs). NOD2 is a 110 kDa cytoplasmic protein belonging to the Nod-like receptor (NLR) family. Its expression is largely restricted to monocytes and other antigen-presenting cells (APCs). Proteins in the NLR family all contain a nucleotide-binding oligomerization domain (NOD) responsible for coordinating protein oligomerization. NOD2 also contains a C-terminal leucine-rich repeat (LRR) domain with 11 LRR repeats. The LRR domain coordinates ligand binding and other protein-protein interactions. NOD2 also contains two N-terminal caspase associated recruitment domains (CARDs). The ...

SDHA - An essential Krebs cycle enzyme with role in cancer and metabolism

Thursday, October 22, 2015 - 14:35

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...

Caspase 9 - an important apoptosis marker

Wednesday, October 21, 2015 - 14:44

Caspases are essential mediators of programmed cell death and are needed for both the induction of apoptosis as well as for aiding the degradation of cellular structures. Initiator caspases (such as Caspase-9) sense and respond to various signals including intracellular stress or binding of the death receptor to external ligands. Upon dimerization, initiator caspases gets activated, which follows cleavage of downstream effector caspases for carrying out the apoptotic program. Caspase-9 is activated through its association with Apaf-1 (apoptotic protease-activating factor-1) apoptosome complex (1). While cleavage is not required for caspase-9 activity, in vivo studies have demonstrated cleavage during apoptosis through western blotting with caspase-9 antibodies (1). This suggests caspase-9 cleavage may be important for other events during apoptosis aside from regulating the protein’s enzymatic...


Blog Topics