Antibody News

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...

Caspase 14 - A unique caspase needed for skin differentiation

Monday, October 19, 2015 - 14:54

Caspases are typically known for their role in cell death. However some caspases have recently been investigated for their function during cell proliferation and differentiation. Of these caspase-14 shows a unique expression pattern in the skin and appears to be involved in keratinocyte differentiation. Procaspase-14 is detected in the stratifying epithelium while activated caspase-14 is found only in terminally differentiated keratinocytes (1). Caspase-14 activity is not involved in apoptosis. Instead, caspase-14 is important for keratinization of the epithelium. One of the substrates of activated caspase-14 is profilaggrin, a structural protein that interacts with keratin (1). During keratinization profilaggrin is cleaved into filaggrin monomers to help form a tightly packed and extensively cross-linked keratin matrix (1). Blocking filaggrin processing by caspase-14 results in defects in water retention and protection from UVB irradiation...

ATG4A - protease that initiates ATG8 lipidation during autophagosome elongation

Friday, October 16, 2015 - 14:35

There are 3 major autophagy pathways- microautophagy, chaperone-mediated autophagy, and macroautophagy. Macroautophagy is the pathway herein referred to as simply autophagy.
Autophagy can be broken down into 4 main stages: phagophore nucleation, autophagosome elongation, autophagosome docking and fusion with a lysosome, and vesicle breakdown and degradation. ATG4A is one of four human ATG4 homologs (ATG4A, ATG4B, ATG4C, and ATG4D) involved in autophagosome elongation. ATG4A encodes a 45 kDa protein called autophagin-2 that is a member of the C54 family of cysteine proteases. Like ATG4B, ATG4A does not require any cleavage to enable its catalytic activity. ATG4A cleaves the ubiquitin-like protein ATG8 to expose a C-terminal glycine, allowing further post-...

TGF-beta RIII - A multi-functional regulator of the TGF-beta signaling pathway

Thursday, October 15, 2015 - 12:55

Transforming growth factor-beta receptor III (TGF-beta RIII) is one of three receptors for the secreted growth factor TGF-beta. Unlike type I and type II TGF-beta receptors, TGF-beta RIII does not participate directly in the propagation of intracellular signaling in response to TGF-beta binding (1). TGF-beta RIII typically functions as a coreceptor for TGF-beta by binding the ligand with high affinity in order to regulate signaling. TGF-beta RIII contains a large glycosylated extracellular domain and a small intracellular domain. The extracellular domain can bind ligand and enhance TGF-beta signaling. The receptor can also inhibit signaling by binding to and sequestering ligand (1). One study measured the effect of secreted TGF-beta RIII on sequestration of TGF-beta (2). They performed ELISA with TGF-beta RIII antibody to measure the amount of the secreted protein. Their data demonstrated the...

FADD - important initiator of death receptor-mediated apoptosis

Wednesday, October 14, 2015 - 14:49

FAS-associated death domain protein (FADD) is a 23 kDa adaptor protein involved in initiating apoptosis. FADD is best known for its involvement in extrinsic/death receptor-mediated apoptosis, but it is also involved in initiating necroptosis with serine/threonine kinases RIPK1 and RIPK3 (1). FADD binds to receptors of the tumor necrosis factor (TNF) superfamily through its C-terminal death domain (DD). During extrinsic apoptosis, binding of the Fas-ligand causes trimerization of the Fas-receptor which then binds to FADD via the DD domain. Activated FADD recruits apoptotic pro-caspases to form the death-inducing signal complex (DISC). Formation of the DISC allows cleavage and activation of initiator caspases-8 and -10. Presence of the DD domain is critical to the formation of the DISC and initiation of apoptosis. c-FLIP, PKC, and MKRN1 have all been identified as negative regulators of FADD activity, thus inhibiting apoptosis.

Dysregulation of apoptosis has been...

Cathepsin B - a lysosomal protease with potential of an important drug target in neurological diseases and cancer

Monday, October 12, 2015 - 14:56

Cathepsins are a family of lysosomal proteases (serine, aspartic and cysteine proteases) that acts in conjunction with lipases and nucleases to degrade biological macromolecules in the lysosomes (1). While most cathepsins are ubiquitously expressed to support normal lysosomal degradation, cathepsin B is unique for its role in various pathologies and malignancies (2). Cathepsin B is often overexpressed and alternatively spliced in cancer cells (2). Increased levels of cathepsin B lead to its secretion where it contributes to metastasis through the degradation of extracellular matrix proteins. Cathepsin B also has neuroprotective effects in neurological disorders such as Alzheimer’s and Huntington’s diseases. In these disorders, cathepsin B contributes to the degradation of toxic protein aggregates through autophagy (2).

The role of cathepsin B in diverse cellular processes makes it an important target and ...

SLC34A1 - major regulator of inorganic phosphate (Pi) homeostasis

Friday, October 9, 2015 - 14:53

SLC34A1 encodes the 69 kDa sodium-dependent phosphate transport protein 2A (Npt2a). SLC34A is a member of the type II sodium-phosphate co-transporter family, along with SLC34A3 which encodes Npt2c. These proteins are abundantly expressed along the proximal tubules of the kidneys where most of the filtered inorganic phosphate (Pi) is reabsorbed into the body. Renal reabsorption of Pi directly regulates blood phosphate levels, important for many metabolic processes. While SLC34A1 expression is largely confined to the kidney, it has been identified in tissues from lungs, testes, fallopian tubes, skeletal muscle, and cardiac myocytes. Its role in each of these tissues is yet to be fully characterized.

SLC34A1 mutations have been linked to hypophosphatemia which is characterized by bone demineralization and osteoporosis due to low levels of phosphate in the blood (1). Renal phosphate loss may also lead to the formation of calcium stones /nephrolithiasis (2). Due to...

Caspase-12 - activator of apoptosis via the ER stress response

Thursday, October 8, 2015 - 14:24

Aside from their important role in apoptosis, caspases also play an important role in inflammatory processes. Humans express four inflammatory caspases: Caspase-1, -4, -5, and -12. Caspase-12 is a 48 kDa protein localized to the ER and involved in the ER stress response. Caspase-12 contains a caspase-associated recruitment domain (CARD) and two catalytic domains, p20 and p10 (1). The ER stress response is important for maintaining ER homeostasis to allow proper lipid synthesis, calcium storage, and protein folding and maturation. The ER stress response is also known as the unfolded protein response (UPR) and ultimately results in apoptosis. The UPR can be triggered by two mechanisms- a transcription factor-dependent pathway or a caspase-dependent pathway. Caspase-12 plays an important role in...

MCP-1 - chemoattractant protein involed in monocyte migration and infiltration

Wednesday, October 7, 2015 - 14:27

Monocyte chemotractant protein-1 (MCP-1), also known as CCL2, is a key chemokine involved in the migration of monocytes and macrophages to sites of active inflammation. It is a member of the C-C/beta family of cytokines, characterized by the Cys-Cys sequence at its N-terminus (1). MCP-1 is tethered to endothelial cells via glycosaminoglycans within the plasma membrane (2). MCP-1 cleavage by MMP-12 is necessary for MCP-1 to interact with its receptor CCR2. MCP-1 activation recruits monocytes to vascular endothelium during active inflammation and also for regular immune surveillance. MCP-1 has been implicated to play a role in disorders such as psoriasis, atherosclerosis, multiple sclerosis, and rheumatoid arthritis- all of which display a predominately monocytic infiltrate (3).

Gilbert et. al. used the MCP-1 antibody (5D3-F7) to assess the expression of MCP-1 in testicular...

FcRn - neonatal Fc receptor encoded by the FCGRT gene

Monday, October 5, 2015 - 14:48

Antibodies play an important role in the innate immune system by circulating in the bloodstream to fight off invading pathogens. IgG is the most prevalent of the five classes of antibodies (IgA, IgD, IgE, IgG, and IgM) and is the only one transmitted from a mother to her offspring. IgG is transported across the epithelium of the placenta by the neonatal Fc receptor (FcRn) (1). FcRn is a 40 kDa protein encoded by the FCGRT gene. FcRn binds to the Fc domain of IgG and transports the antibody in a pH dependent mechanism. Outside of the neonatal period, FcRn continues to play a role in IgG regulation. FcRn binds to IgG in the serum to prolong the half-life of this immunoprotective antibody. It has also been suggested that FcRn binds to albumin and serves the same protective purpose (2). Modification of the FcRn-IgG interaction is being studied as a strategy to increase the lifespan of therapeutic antibodies or to shorten the lifespan of pathogenic antibodies, such as those...

Caspase 11 - A proinflammatory caspase that induces the innate immune response

Friday, October 2, 2015 - 14:51

While known for their role in programmed cell death, caspases are also essential for mediating inflammatory responses and innate immunity. Binding of microbial molecules by pattern recognition receptors triggers the formation of the multiprotein inflammasome complex and the activation of caspase-1 (1). Caspase-1 is then able to mediate the activation and secretion of proinflammatory cytokines including interleukin-1. In addition to caspase-1, caspase-11 also plays an important role during the inflammatory response. Depending on the type of pathogen infection, casapse-11 is needed for caspase-1 activation and the processing of proinflammatory cytokines (1). This alternative pathway to inflammasome activation represents a noncanonical proinflammatory mechanism that is currently under investigation (1). Unlike other caspase family members, expression of caspase-11 is induced by inflammatory stimulation....


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