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  • Apolipoprotein JClusterin in Human Erythrocytes Is Involved in the Molecular Process of Defected Material Disposal during Vesiculation. 22016805

    We have showed that secretory Apolipoprotein J/Clusterin (sCLU) is down-regulated in senescent, stressed or diseased red blood cells (RBCs). It was hypothesized that sCLU loss relates to RBCs vesiculation, a mechanism that removes erythrocyte membrane patches containing defective or potentially harmful components.
    Document Type:
    Reference
    Product Catalog Number:
    S7150
    Product Catalog Name:
    OxyBlot Protein Oxidation Detection Kit
  • Transsynaptic activity-dependent regulation of axon branching and neurotrophin expression in vivo. 21900550

    The two major classes of activity-dependent neuroplasticity predict different consequences of activity alteration on circuit response. Hebbian plasticity (positive feedback) posits that alteration of neuronal activity causes a parallel response within a circuit. In contrast, homeostatic plasticity (negative feedback) predicts that altering neuronal activity results in compensatory responses within a circuit. The relative roles of these modes of plasticity in vivo are unclear, since neuronal circuits are difficult to manipulate in the intact organism. In this study, we tested the in vivo effects of activity deprivation in the superior cervical ganglion-pineal circuit of adult rats, which can be noninvasively silenced by exposing animals to constant light. We demonstrated that total deprivation of sympathetic activity markedly decreased the presence of axonal proteins in the pineal and reduced the density and thickness of sympathetic axonal arbors. In addition, we demonstrated that sympathetic inactivity eliminated pineal function and markedly decreased pineal expression of neurotrophins. Administration of β-adrenergic agonist restored the expression of presynaptic and postsynaptic proteins. Furthermore, compensatory axonal growth through collateral sprouting, normally seen following unilateral denervation of the pineal, was profoundly impaired in the absence of neural activity. Thus, these data suggest that sympathetic axonal terminals are maintained by neural activity that induces neurotrophins, which may act through a retrograde mechanism to preserve the integrity of axonal arbors via a positive feedback loop. Conversely, by using Hebbian-like neuroplasticity, silent yet intact circuits enter a hibernation mode marked by reduction of presynaptic axonal structures and dramatically reduced postsynaptic expression of neurotrophins.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • Spatial differences within the membrana granulosa in the expression of focimatrix and steroidogenic capacity. 22863478

    In the ovarian follicular membrana granulosa there are morphological and functional differences between cells adjacent to the follicular fluid lumen, or aligning the basal lamina. Amongst the observed functional differences are steroidogenic capacity and expression levels of a novel basal lamina, focimatrix; both of which increase in the later stages of antral follicle growth. A number of different studies have produced apparently inconsistent results as to which cell layers are more steroidogenic. To examine this systematically, individual bovine follicles, confirmed as healthy by post hoc histological examination, were used to isolate populations of apical and basal granulosa cells. Cell counts revealed that the respective groups did not differ in the numbers of cells, thus confirming the separation of these populations. We measured gene expression (quantitative RT-PCR, n=8-10, follicle diameter 14.0
    Document Type:
    Reference
    Product Catalog Number:
    AP132P
    Product Catalog Name:
    Goat Anti-Rabbit IgG Antibody, Peroxidase Conjugated
  • CHFR protein regulates mitotic checkpoint by targeting PARP-1 protein for ubiquitination and degradation. 22337872

    The mitotic checkpoint gene CHFR (checkpoint with forkhead-associated (FHA) and RING finger domains) is silenced by promoter hypermethylation or mutated in various human cancers, suggesting that CHFR is an important tumor suppressor. Recent studies have reported that CHFR functions as an E3 ubiquitin ligase, resulting in the degradation of target proteins. To better understand how CHFR suppresses cell cycle progression and tumorigenesis, we sought to identify CHFR-interacting proteins using affinity purification combined with mass spectrometry. Here we show poly(ADP-ribose) polymerase 1 (PARP-1) to be a novel CHFR-interacting protein. In CHFR-expressing cells, mitotic stress induced the autoPARylation of PARP-1, resulting in an enhanced interaction between CHFR and PARP-1 and an increase in the polyubiquitination/degradation of PARP-1. The decrease in PARP-1 protein levels promoted cell cycle arrest at prophase, supporting that the cells expressing CHFR were resistant to microtubule inhibitors. In contrast, in CHFR-silenced cells, polyubiquitination was not induced in response to mitotic stress. Thus, PARP-1 protein levels did not decrease, and cells progressed into mitosis under mitotic stress, suggesting that CHFR-silenced cancer cells were sensitized to microtubule inhibitors. Furthermore, we found that cells from Chfr knockout mice and CHFR-silenced primary gastric cancer tissues expressed higher levels of PARP-1 protein, strongly supporting our data that the interaction between CHFR and PARP-1 plays an important role in cell cycle regulation and cancer therapeutic strategies. On the basis of our studies, we demonstrate a significant advantage for use of combinational chemotherapy with PARP inhibitors for cancer cells resistant to microtubule inhibitors.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1501R
    Product Catalog Name:
    Anti-Actin Antibody,clone C4
  • Cellular settings mediating Src Substrate switching between focal adhesion kinase tyrosine 861 and CUB-domain-containing protein 1 (CDCP1) tyrosine 734. 21994943

    Reciprocal interactions between Src family kinases (SFKs) and focal adhesion kinase (FAK) are critical during changes in cell attachment. Recently it has been recognized that another SFK substrate, CUB-domain-containing protein 1 (CDCP1), is differentially phosphorylated during these events. However, the molecular processes underlying SFK-mediated phosphorylation of CDCP1 are poorly understood. Here we identify a novel mechanism in which FAK tyrosine 861 and CDCP1-Tyr-734 compete as SFK substrates and demonstrate cellular settings in which SFKs switch between these sites. Our results show that stable CDCP1 expression induces robust SFK-mediated phosphorylation of CDCP1-Tyr-734 with concomitant loss of p-FAK-Tyr-861 in adherent HeLa cells. SFK substrate switching in these cells is dependent on the level of expression of CDCP1 and is also dependent on CDCP1-Tyr-734 but is independent of CDCP1-Tyr-743 and -Tyr-762. In HeLa CDCP1 cells, engagement of SFKs with CDCP1 is accompanied by an increase in phosphorylation of Src-Tyr-416 and a change in cell morphology to a fibroblastic appearance dependent on CDCP1-Tyr-734. SFK switching between FAK-Tyr-861 and CDCP1-Tyr-734 also occurs during changes in adhesion of colorectal cancer cell lines endogenously expressing these two proteins. Consistently, increased p-FAK-Tyr-861 levels and a more epithelial morphology are seen in colon cancer SW480 cells silenced for CDCP1. Unlike protein kinase Cδ, FAK does not appear to form a trimeric complex with Src and CDCP1. These data demonstrate novel aspects of the dynamics of SFK-mediated cell signaling that may be relevant during cancer progression.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • Human protein arginine methyltransferases in vivo--distinct properties of eight canonical members of the PRMT family. 19208762

    Methylation of arginine residues is a widespread post-translational modification of proteins catalyzed by a small family of protein arginine methyltransferases (PRMTs). Functionally, the modification appears to regulate protein functions and interactions that affect gene regulation, signalling and subcellular localization of proteins and nucleic acids. All members have been, to different degrees, characterized individually and their implication in cellular processes has been inferred from characterizing substrates and interactions. Here, we report the first comprehensive comparison of all eight canonical members of the human PRMT family with respect to subcellular localization and dynamics in living cells. We show that the individual family members differ significantly in their properties, as well as in their substrate specificities, suggesting that they fulfil distinctive, non-redundant functions in vivo. In addition, certain PRMTs display different subcellular localization in different cell types, implicating cell- and tissue-specific mechanisms for regulating PRMT functions.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • Orexin A decreases lipid peroxidation and apoptosis in a novel hypothalamic cell model. 22796468

    Current data support the idea that hypothalamic neuropeptide orexin A (OxA; hypocretin 1) mediates resistance to high fat diet-induced obesity. We previously demonstrated that OxA elevates spontaneous physical activity (SPA), that rodents with high SPA have higher endogenous orexin sensitivity, and that OxA-induced SPA contributes to obesity resistance in rodents. Recent reports show that OxA can confer neuroprotection against ischemic damage, and may decrease lipid peroxidation. This is noteworthy as independent lines of evidence indicate that diets high in saturated fats can decrease SPA, increase hypothalamic apoptosis, and lead to obesity. Together data suggest OxA may protect against obesity both by inducing SPA and by modulation of anti-apoptotic mechanisms. While OxA effects on SPA are well characterized, little is known about the short- and long-term effects of hypothalamic OxA signaling on intracellular neuronal metabolic status, or the physiological relevance of such signaling to SPA. To address this issue, we evaluated the neuroprotective effects of OxA in a novel immortalized primary embryonic rat hypothalamic cell line. We demonstrate for the first time that OxA increases cell viability during hydrogen peroxide challenge, decreases hydrogen peroxide-induced lipid peroxidative stress, and decreases caspase 3/7 induced apoptosis in an in vitro hypothalamic model. Our data support the hypothesis that OxA may promote obesity resistance both by increasing SPA, and by influencing survival of OxA-responsive hypothalamic neurons. Further identification of the individual mediators of the anti-apoptotic and peroxidative effects of OxA on target neurons could lead to therapies designed to maintain elevated SPA and increase obesity resistance.
    Document Type:
    Reference
    Product Catalog Number:
    AB3092
    Product Catalog Name:
    Anti-Orexin-1 Receptor Antibody
  • MyoD directly up-regulates premyogenic mesoderm factors during induction of skeletal myogenesis in stem cells. 21078671

    Gain- and loss-of-function experiments have illustrated that the family of myogenic regulatory factors is necessary and sufficient for the formation of skeletal muscle. Furthermore, MyoD required cellular aggregation to induce myogenesis in P19 embryonal carcinoma stem cells. To determine the mechanism by which stem cells can be directed into skeletal muscle, a time course of P19 cell differentiation was examined in the presence and absence of exogenous MyoD. By quantitative PCR, the first MyoD up-regulated transcripts were the premyogenic mesoderm factors Meox1, Pax7, Six1, and Eya2 on day 4 of differentiation. Subsequently, the myoblast markers myogenin, MEF2C, and Myf5 were up-regulated, leading to skeletal myogenesis. These results were corroborated by Western blot analysis, showing up-regulation of Pax3, Six1, and MEF2C proteins, prior to myogenin protein expression. To determine at what stage a dominant-negative MyoD/EnR mutant could inhibit myogenesis, stable cell lines were created and examined. Interestingly, the premyogenic mesoderm factors, Meox1, Pax3/7, Six1, Eya2, and Foxc1, were down-regulated, and as expected, skeletal myogenesis was abolished. Finally, to identify direct targets of MyoD in this system, chromatin immunoprecipitation experiments were performed. MyoD was observed associated with regulatory regions of Meox1, Pax3/7, Six1, Eya2, and myogenin genes. Taken together, MyoD directs stem cells into the skeletal muscle lineage by binding and activating the expression of premyogenic mesoderm genes, prior to activating myoblast genes.
    Document Type:
    Reference
    Product Catalog Number:
    PP64
    Product Catalog Name:
    IgG, Rabbit
  • Gfi1 expressed in bone marrow stromal cells is a novel osteoblast suppressor in patients with multiple myeloma bone disease. 22042697

    Protracted inhibition of osteoblast (OB) differentiation characterizes multiple myeloma (MM) bone disease and persists even when patients are in long-term remission. However, the underlying pathophysiology for this prolonged OB suppression is unknown. Therefore, we developed a mouse MM model in which the bone marrow stromal cells (BMSCs) remained unresponsive to OB differentiation signals after removal of MM cells. We found that BMSCs from both MM-bearing mice and MM patients had increased levels of the transcriptional repressor Gfi1 compared with controls and that Gfi1 was a novel transcriptional repressor of the critical OB transcription factor Runx2. Trichostatin-A blocked the effects of Gfi1, suggesting that it induces epigenetic changes in the Runx2 promoter. MM-BMSC cell-cell contact was not required for MM cells to increase Gfi1 and repress Runx2 levels in MC-4 before OBs or naive primary BMSCs, and Gfi1 induction was blocked by anti-TNF-α and anti-IL-7 antibodies. Importantly, BMSCs isolated from Gfi1(-/-) mice were significantly resistant to MM-induced OB suppression. Strikingly, siRNA knockdown of Gfi1 in BMSCs from MM patients significantly restored expression of Runx2 and OB differentiation markers. Thus, Gfi1 may have an important role in prolonged MM-induced OB suppression and provide a new therapeutic target for MM bone disease.
    Document Type:
    Reference
    Product Catalog Number:
    05-924
    Product Catalog Name:
    Anti-GFI1 Antibody, clone 2.5D.17
  • Differential role of beta-arrestin ubiquitination in agonist-promoted down-regulation of M1 vs M2 muscarinic acetylcholine receptors. 19055777

    Sustained agonist-promoted ubiquitination of beta-arrestin has been correlated with increased stability of the GPCR - beta-arrestin complex. Moreover, abrogation of beta-arrestin ubiquitination has been reported to inhibit receptor internalization with minimal effects on receptor degradation.Herein we report that agonist activation of M1 mAChRs produces a sustained beta-arrestin ubiquitination but no stable co-localization with beta-arrestin. In contrast, sustained ubiquitination of beta-arrestin by activation of M2 mAChRs does result in stable co-localization between the M2 mAChR and beta-arrestin. Internalization of receptors was unaffected by proteasome inhibitors, but down-regulation was significantly reduced, suggesting a role for the ubiquitination machinery in promoting down-regulation of the receptors. Given the ubiquitination status of beta-arrestin following agonist treatment, we sought to determine the effects of beta-arrestin ubiquitination on M1 and M2 mAChR down-regulation. A constitutively ubiquitinated beta-arrestin 2 chimera in which ubiquitin is fused to the C-terminus of beta-arrestin 2 (YFP-beta-arrestin 2-Ub) significantly increased agonist-promoted down-regulation of both M1 and M2 mAChRs, with the effect substantially higher on the M2 mAChR. Based on this observation, we were interested in examining the effects of disruption of potential ubiquitination sites in the beta-arrestin sequence on receptor down-regulation. Agonist-promoted internalization of the M2 mAChR was not affected by expression of beta-arrestin lysine mutants lacking putative ubiquitination sites, beta-arrestin 2K18R, K107R, K108R, K207R, K296R, while down-regulation and stable co-localiztion of the receptor with this beta-arrestin lysine mutant were significantly reduced. Interestingly, expression of beta-arrestin 2K18R, K107R, K108R, K207R, K296R increased the agonist-promoted down-regulation of the M1 mAChR but did not result in a stable co-localiztion of the receptor with this beta-arrestin lysine mutant.These findings indicate that ubiquitination of beta-arrestin has a distinct role in the differential trafficking and degradation of M1 and M2 mAChRs.
    Document Type:
    Reference
    Product Catalog Number:
    AP132F
    Product Catalog Name:
    Goat Anti-Rabbit IgG Antibody, FITC conjugate