Faces of DARPP-32: Master Signaling Mediator in the Brain?

As a major target for dopamine-activated adenylyl cyclase and protein kinase A in the striatum, DARPP-32 plays a central role in regulating the efficacy of dopaminergic neurotransmission and can act either as a phosphatase or kinase inhibitor in a contextually dependent manner. Growing evidence points to DARPP-32 as a key mediator/modulator in numerous signal transduction cascades implicated in a growing number of neurological disorders such as schizophrenia and depression, as well as in drug abuse and addiction. For example, it has been shown that acute exposure of mice to cocaine increases phosphorylation of DARPP-32 at Thr34 with a concommitment decrease in phosphorylation at Thr75, whereas chronic exposure leads to a reversal of this phospho profile. It has also been observed that many schizophrenic patients show decreased levels of DARPP-32 in the prefrontal cortex.

While the precise role that DARPP-32 plays in these psychiatric disorders is still being elucidated, the existing body of literature clearly portrays DARPP-32 as playing a central role in multiple signaling pathways. Further research will determine neuronal subpopulations where phosphorylation of DARPP-32 occurs as well as the functional importance of previously identified phospho sites of DARPP-32.

IMGENEX offers over one-thousand Neuroscience-related antibodies such as recently cited anti-DARPP-32 (pan and phosphospecific), Dopamine D1 and D2 Receptors (IHC validated), 5-HT Receptors (such as 5-HT1B), Adenosine Receptor, NMDA and more!

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about DARPP-32.

Transcriptional Factors And Regulators.

All the cellular processes in living cells such as growth, development, morphogenesis and cellular differentiation are a product of gene expression programs involving complicated transcriptional regulation of several genes. This process of transcriptional regulation is tightly controlled and coordinated by proteins called transcriptional regulators. These transcriptional regulators and factors are DNA-binding proteins that bind to the promoter or enhancer sequences on the DNA and facilitate either transcriptional repression or activation.

There are three principal types of transcription factors. These include basal transcription factors, upstream transcription factors and inducible transcription factors. The basic structure of every transcriptional factor mainly contains a DNA-binding domain and an activator domain. DNA-binding motifs found in transcription factors include zinc-finger, helix-loop-helix, helix-turn-helix, leucine zipper and high-mobility groups, based on which transcription factors are classified. The activator domain of these transcription factors interacts with components of transcription machinery such as RNA polymerases and associated transcription regulators.

Regulation of transcriptional factors is a complex mechanism that ensures exact spatio-temporal expression of genes. In response to a specific cellular stimulus, these trans-regulatory factors are activated in a sequential manner. Upon activation, these factors recruit transcriptional co-regulators such as histones that function as co-activators or co- repressors and aid in modifying chromatin structure. Altered activation of these regulators is often associated with various pathologies such as chronic disorders and malignancies. Recent studies are concentrating on developing improved disease treatment strategies through identification of different transcription factor-binding patterns and blocking them.

There are several families of trans-regulatory factors that control critical cellular signaling cascades involved in cell proliferation, survival, lineage development and cellular differentiation. These include Rel/NF-kB family, AP-1 family, STAT family of transcription factors, homeodomain proteins, DNA-binding proteins, POU transcription factors, nuclear hormone receptor family, p53 family and E2F family.

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA.Find out more information about Transcriptional Factors.

Fundamental Immunology, Basic Immunology and Allergy Immunology

Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. The immune system is the body's defense against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade our systems and cause disease. The immune system is made up of a network of cells, tissues, and organs that work together to protect the body. The immune system is the body’s natural defence in combating organisms. The immune system usually have two lines of defence: the innate immune system representing a non-specific (no memory) response to antigen (substance to which the body regards as foreign or potentially harmful) and the adaptive immune system, which displays a high degree of memory and specificity. The innate system represents the first line of defence to an intruding pathogen and includes various cells like the natural killer (NK) cells, mast cells dendritic cells and phagocytes. Besides there are molecules like complement, acute phase proteins (APP) and interferons (IFNs) which work in concert with the cells of the innate immune system and which foster close functional links with their adaptive counterpart. The adaptive immune system is further divided into humoral and cellular components. Cell-mediated immunity, also known as delayed-type hypersensitivity (DTH) or Type IV Hypersensitivity, is an immune response that does not involve antibodies but rather involves the activation of macrophages, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. The humoral immune response (HIR) is the aspect of immunity that is mediated by secreted antibodies, produced in the cells of the B lymphocyte lineage (B cell). When activated by foreign antigen, B cells undergo proliferation and mature into antibody secreting plasma cells which posses the ability to secrete soluble proteins (antibodies). Antibodies which are classified into five different types (known as isotypes), namely IgM, IgG, IgA, IgE and IgD, have two roles to play - the first is to bind antigen and the second is to interact with host tissues and effector systems in order to ensure removal of the antigen. Thus the immune system generally is protective, however the same immunologic mechanisms that defend the host at times may result in severe damage to tissues and, occasionally, may cause death.

Conceptualizing the natural antigen- antibody development & interaction, Imgenex Corp. develops and commercializes novel reagents for the scientific study of human biology and disease and for the production of new diagnostic assays and potential therapies of such diseases. These novel reagents include antibodies, gene and protein expression systems, and arrays of various cells and tissues for use in studies of functional genomics. Areas of biological interest at IMGENEX include cancer, apoptosis (programmed cell death), molecular signaling pathways, cellular aging, and metabolic and infectious diseases.

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about immunology.

Apoptosis Programmed Cell Death.

Apoptosis is regulated by death domain (DD) and/or caspase recruitment domain (CARD) containing molecules and a caspase family of proteases. A novel CARD domain containing protein was recently identified and designated ARC for apoptosis repressor with CARD (1). For more details read out the article:

Coined in the 1960's,apoptosis is derived from the Greek word apopiptein which means to fall off from. Apoptosis can be induced by a number of stimuli including UV damage, irradiation, drug treatment, or tumor necrosis factor. Once induced, apoptosis can, in turn, act through a number of different cell death signaling pathways.

The number of apoptosis and 'programmed cell death' related kits and reagents available to the market have increased significantly over the last few years. This is in large part the result of increasing evidence implicating the role of apoptosis in a number of significantly relevant disease processes including certain autoimmune diseases, transplantation rejection, and neurodegenerative diseases. IMGENEX offers over 200 Apoptosis related antibodies, as well as ELISA kits, caspase inhibitors, active caspase detection kits, apoptosis detection kits, and mitochondrial permeability detection kits.

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about Apoptosis.

Regulatory T Cells (Treg)

Early development and differentiation of nascent T cells that migrate from bone marrow to become mature, naïve T cells, which are capable of responding to antigen takes place inside the thymus. Around 10¹⁰ TCR (T cell receptor) variations are generated in developing T lymphocyte clones through a random process of somatic cell gene reorganization. During this process, often T-cells recognizing self-antigens are generated. Due to the ability of these self-reactive T-cells to elicit an autoimmune attack, they are permanently removed by the thymus through negative selection and clonal deletion. But, some of them manage to escape the thymic defenses and harbor themselves in the peripheral lymphoid organs. In periphery, T lymphocytes undergo further differentiation into effectors of various immune functions.

One of many immunotolerance mechanisms that immune system has developed to distinguish between self and non-self antigens is regulatory T cells or Tregs. These cells are recently characterized specialized T-cell subsets that actively suppress a variety of immune responses. Researchers have broadly classified Tregs into natural and adaptive Tregs. Natural Tregs are CD4⁺CD25⁺ T-cells that originate in the thymus and play a significant role in immune homeostasis and protection against autoimmunity. Adaptive Tregs are non-regulatory CD4⁺ T-cells that have up-regulated CD25 expression during pathological and inflammatory conditions such as cancers and infections.

Although the principal immunosuppressive mechanism of Tregs remains elusive, several in vivo experimental models have indicated that Tregs secrete large amounts of immunosuppressants including IL-9, IL-10 and TGF-β upon activation. These lymphokines are capable of inhibiting activation of Th1, Th2 cells and CTLs required for cell-mediated immunity, inflammation and antibody production. Certain recent experimental data and results even indicate that IL-2-IL-2R signaling is vital for development, maintenance, survival, expansion and suppressive activity of Tregs. Increased expression of certain other characteristic markers including CTLA-4, glucocorticoid-inducible tumor necrosis factor receptor (GITR) and OX40 has been identified on Tregs whose function inside these cells is still not clear. The TCRs displayed on Tregs are capable of recognizing and interacting with any peptide-MHC class II ligand having certain range of avidity. But, the contribution of TCR signaling and role of TCR-ligand interactions towards regulatory T-cell development needs to be determined.

Several elegant experiment using transgenic mice and retrovirus mediate over expression studies, researchers have identified FoxP3, a transcription factor, to be a specific molecular marker essential for the development and function of Tregs. The primary evidence regarding the involvement of FoxP3 in the development of Tregs was provided by the experiments of Sakaguchi et al, (ref ?) in patients suffering from IPEX, a rare and fatal human autoimmune disorder. In these patients, mutated FoxP3 gene causes improper development of Tregs resulting in hyperactivation of T-cells reactive to self-antigens. Recently, experiments have clearly shown that retroviral mediated introduction of FoxP3 into conventional CD4+ T-cells converts them into regulatory T-cells.

The emergence of regulatory T-cells and role of FoxP3 as a critical player in the negative control of a of various normal and pathological immune responses holds great promise for the development of novel therapies useful for the treatment of autoimmune diseases in humans. However, there are several questions that remain to be answered including the basic biology of the Tregs, various ligands responsible for thymic selection of these cells, the exact function of FoxP3 in relation with various markers present on Tregs and most importantly, the mechanisms by which Tregs exert their suppressive effects. A better understanding of manipulating FoxP3 and Tregs would enable us to harness the tremendous therapeutic potential in various clinical situations including Type I diabetes, Multiple sclerosis, GVHD, rheumatoid arthritis, allergy, and cancers.

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about Regulator T-cells(Treg).

Actin Antibody Available in Imgenex now

Actin is a ubiquitous protein involved in the formation of filaments that are major components of the cytoskeleton. It is the monomeric subunit of microfilaments, one of the three major components of the cytoskeleton, and of thin filaments which are part of the contractile apparatus in muscle cells. It is the most abundant protein in the typical eukaryotic cell, accounting for about 15% in some cell types. The protein is highly conserved, and forms a huge variety of structure in cells in concert with a huge numbers of actin binding proteins. The actin filaments interact with myosin to produce a sliding effect, which is the basis of muscular contraction and many aspects of cell motility, including cytokinesis. The individual subunits of actin are known as globular actin (G-actin) that assembles into long filamentous polymers called F-actin. Two parallel F-actin strands twist around each other in a helical formation, giving rise to microfilaments of the cytoskeleton. Microfilaments measure approximately 7 nm in diameter with a loop of the helix repeating every 37nm. Each actin protomer binds one molecule of ATP and has one high affinity site for either calcium or magnesium ions, as well as several low affinity sites. It exists as a monomer in low salt concentrations, but filaments form rapidly as salt concentration rises, with the consequent hydrolysis of ATP. Actin from many sources forms a tight complex with deoxyribonuclease (DNase I) although the significance of this is still unknown. The formation of this complex results in the inhibition of DNase I activity, and actin loses its ability to polymerise. It has been shown that an ATPase domain of actin shares similarity with ATPase domains of hexokinase and hsp70 proteins. In vertebrates there are three groups of actin isoforms: alpha, beta and gamma. The alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. The beta and gamma actins co-exist in most cell types as components of the cytoskeleton and as mediators of internal cell motility. MreB, a major component of the bacterial cytoskeleton, exhibits high structural homology to its eukaryotic counterpart actin. Further it has been suggested that members of the Rho family of small guanosine triphosphatases have emerged as key regulators of the actin cytoskeleton, and through their interaction with multiple target proteins, they ensure coordinated control of other cellular activities such as gene transcription and adhesion.

Reference:

1. Actin isoforms. Curr Opin Cell Biol. 1993 Feb;5(1):48-55 Herman IM
2. The assembly of MreB, a prokaryotic homolog of actin. The assembly of MreB, a prokaryotic homolog of actin. J Biol Chem. 2005 Jan 28;280(4):2628-35. Epub 2004 Nov 16
3. Rho GTPases and the Actin Cytoskeleton Science 23 January 1998:
   Vol. 279. no. 5350, pp. 509 – 514 Alan Hall

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about Actin antibody.

Akt Family: Antibodies from Imgenex

Akt family of serine/threonine-directed kinases regulates a diverse array of biological processes, including cellular survival, proliferation, glucose homeostasis, and vascular tone and are important molecules in mammalian cellular signaling. The three widely expressed isoforms of PKB (PKB, PKBß and PKB; also known as Akt1, Akt2 and Akt3, respectively) are each composed of an N-terminal PtdIns(3,4,5)P₃- and PtdIns(3,4)P₂-binding PH domain and a C-terminal kinase catalytic domain. Stimulation by numerous growth factors, cytokines, hormones and neurotransmitters can activate PKB/Akt in a phosphoinositide 3-kinase-dependent manner. Through receptor tyrosine kinases, these stimuli cause phosphoinositide 3-kinase activation, and generation of the membrane phospholipid PtdIns(3,4,5)P3. PtdIns(3,4,5)P3 then recruits PKB/Akt to the membrane, where it becomes phosphorylated (for PKBa/Akt1) by upstream kinases, phosphoinositide-dependent kinase 1. Following the activation of PI 3-kinase, PKB isoforms are recruited from the cytosol to the plasma membrane through their interaction with PtdIns(3,4,5)P₃ and/or PtdIns(3,4)P₂ where they are thought to undergo a conformational change and become activated by phosphorylation of two residues. PKB can promote cell survival by inhibiting proteins that mediate apoptosis. Phosphorylation of BAD by PKB (and other AGC kinases) enables it to interact with 14-3-3 proteins, which prevents it from binding to Bcl-X_L and thereby suppresses apoptosis. It directly phosphorylate and inhibit the caspase proteasesm, key executioners of apoptosis. PKBbeta, an essential gene for the maintenance of normal glucose homeostasis and is likely to represent a critical intermediate in the insulin signal transduction pathway. PKB activation might inhibit apoptosis by promoting the increased expression of survival molecules or the degradation of pro-apoptotic molecules. PKB also phosphorylates and activates endothelial nitric oxide synthase, thereby promoting angiogenesis (formation of new blood vessels). Inhibition of GSK3 following its phosphorylation by PKB has also been suggested to play a role in inhibiting apoptosis in neuronal cells. Thus it plays a key role in cancer progression by stimulating cell proliferation and inhibiting apoptosis, which suggests it, likely to be a hot drug target for the treatment of cancer, diabetes and stroke.

IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about Akt Family.