CDK12-mediated transcriptional regulation of noncanonical NF-κB components is essential for signaling

Members of the family of nuclear factor κB (NF-κB) transcription factors are critical for multiple cellular processes, including regulating innate and adaptive immune responses, cell proliferation, and cell survival. Canonical NF-κB complexes are retained in the cytoplasm by the inhibitory protein IκBα, whereas noncanonical NF-κB complexes are retained by p100. Although activation of canonical NF-κB signaling through the IκBα kinase complex is well studied, few regulators of the NF-κB-inducing kinase (NIK)-dependent processing of noncanonical p100 to p52 and the subsequent nuclear translocation of p52 have been identified. We discovered a role for cyclin-dependent kinase 12 (CDK12) in transcriptionally regulating the noncanonical NF-κB pathway. High-content phenotypic screening identified the compound 919278 as a specific inhibitor of the lymphotoxin β receptor (LTβR), and tumor necrosis factor (TNF) receptor superfamily member 12A (FN14)-dependent nuclear translocation of p52, but not of the TNF-α receptor-mediated nuclear translocation of p65. Chemoproteomics identified CDK12 as the target of 919278. CDK12 inhibition by 919278, the CDK inhibitor THZ1, or siRNA-mediated knockdown resulted in similar global transcriptional changes and prevented the LTβR- and FN14-dependent expression of MAP3K14 (which encodes NIK) as well as NIK accumulation by reducing phosphorylation of the carboxyl-terminal domain of RNA polymerase II. By coupling a phenotypic screen with chemoproteomics, we identified a pathway for the activation of the noncanonical NF-κB pathway that could serve as a therapeutic target in autoimmunity and cancer.

Glucose-regulated protein 78 autoantibody associates with blood-brain barrier disruption in neuromyelitis optica

Neuromyelitis optica (NMO) is an inflammatory disorder mediated by antibodies to aquaporin-4 (AQP4) with prominent blood-brain barrier (BBB) breakdown in the acute phase of the disease. Anti-AQP4 antibodies are produced mainly in the periphery, yet they target the astrocyte perivascular end feet behind the BBB. We reasoned that an endothelial cell-targeted autoantibody might promote BBB transit of AQP4 antibodies and facilitate NMO attacks. Using monoclonal recombinant antibodies (rAbs) from patients with NMO, we identified two that strongly bound to the brain microvascular endothelial cells (BMECs). Exposure of BMECs to these rAbs resulted in nuclear translocation of nuclear factor κB p65, decreased claudin-5 protein expression, and enhanced transit of macromolecules. Unbiased membrane proteomics identified glucose-regulated protein 78 (GRP78) as the rAb target. Using immobilized GRP78 to deplete GRP78 antibodies from pooled total immunoglobulin G (IgG) of 50 NMO patients (NMO-IgG) reduced the biological effect of NMO-IgG on BMECs. GRP78 was expressed on the surface of murine BMECs in vivo, and repeated administration of a GRP78-specific rAb caused extravasation of serum albumin, IgG, and fibrinogen into mouse brains. Our results identify GRP78 antibodies as a potential component of NMO pathogenesis and GRP78 as a candidate target for promoting central nervous system transit of therapeutic antibodies.

Abstract 1646: In vivo target validation in orthotopic hepatocellular carcinoma model using formulated siRNA

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and its incidence continues to increase. Although there are approved therapies for HCC, the prognosis remains poor. The 5-year survival rate is < 5%. Nucleic acid-based therapeutics such as RNAi may improve patient outcome. Nevertheless, target identification/validation for HCC and delivery of siRNA are major challenges facing the development of HCC-specific RNAi based therapeutics. To enable target validation in vivo using RNAi, we have developed nanolipid siRNA formulations for the in vivo delivery of siRNA to orthotopic tumors. PK/PD studies in model systems demonstrate that up to 80% knockdown of target protein is achievable within tumors and that significant knockdown persists for at least 10 days following a single dose of formulated siRNA. Efficacy studies using similar formulations of siRNAs against potential HCC tumor targets, including mTOR, will be presented.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1646. doi:10.1158/1538-7445.AM2011-1646

IGFBP-5 Metabolism Is Disrupted in the Rat Medial Meniscal Tear Model of Osteoarthritis

Insulin-like growth factor binding protein 5 (IGFBP-5) has been proposed to promote cartilage anabolism through insulin-like growth factor (IGF-1) signaling. A proteolytic activity towards IGFBP-5 has been detected in synovial fluids from human osteoarthritic (OA) joints. The purpose of this study was to determine if protease activity towards IGFBP-5 is present in the rat medial meniscal tear (MMT) model of OA and whether inhibition of this activity would alter disease progression. Sprague-Dawley rats were subject to MMT surgery. Synovial fluid lavages were assessed for the presence of IGFBP-5 proteolytic activity. Treatment animals received intra-articular injections of vehicle or protease inhibitor peptide PB-145. Cartilage lesions were monitored by India ink staining followed by macroscopic measurement of lesion width and depth. The MMT surgery induced a proteolytic activity towards IGFPB-5 that was detectable in joint fluid. This activity was stimulated by calcium and was sensitive to serine protease inhibitors as well as peptide PB-145. Significantly, intra-articular administration of PB-145 after surgery protected cartilage from lesion development. PB-145 treatment also resulted in an increase in cartilage turnover as evidenced by increases in serum levels of procollagen type II C-propeptide (CPII) as well as synovial fluid lavage levels of collagen type II neoepitope (TIINE). IGFBP-5 metabolism is disrupted in the rat MMT model of OA, potentially contributing to cartilage degradation. Inhibition of IGFBP-5 proteolysis protected cartilage from lesion development and enhanced cartilage turnover. These data are consistent with IGFBP-5 playing a positive role in anabolic IGF signaling in cartilage.

Complement 1s is the serine protease that cleaves IGFBP-5 in human osteoarthritic joint fluid

Insulin-like growth factor-I (IGF-I) and IGF binding proteins (IGFBPs) are trophic factors for cartilage and have been shown to be chondroprotective in animal models of osteoarthritis (OA). IGFBP-5 is degraded in joint fluid and inhibition of IGFBP-5 degradation has been shown to enhance the trophic effects of IGF-I.

OBJECTIVE

To determine the identity of IGFBP-5 protease activity in human OA joint fluid.

METHOD

OA joint fluid was purified and the purified material was analyzed by IGFBP-5 zymography.

RESULTS

Both crude joint fluid and purified material contained a single band of proteolytic activity that cleaved IGFBP-5. Immunoblotting of joint fluid for complement 1s (C1s) showed a band that had the same Mr estimate, e.g., 88 kDa. In gel tryptic digestion and subsequent peptide analysis by LC-MS/MS showed that the band contained human C1s. A panel of protease inhibitors was tested for their ability to inhibit IGFBP-5 cleavage by the purified protease. Three serine protease inhibitors, FUT175 and CP-143217 and CB-349547 had IC50's between 1 and 6 microM. Two other serine protease inhibitors had intermediate activity (e.g., IC50's 20-40 microM) and MMP inhibitors had no detectible activity at concentrations up to 300 microM.

CONCLUSION

Human OA fluid contains a serine protease that cleaves IGFBP-5. Zymography, immunoblotting and LC-MS/MS analysis indicate that C1s is the protease that accounts for this activity.

Modulation of the human cytokine response by interferon lambda-1 (IFN-lambda1/IL-29)

The interferon lambda family (IFN-lambda1/2/3) is a newly described group of cytokines that are related to both the type-1 interferons and IL-10 family members. These novel cytokines are induced during viral infection and, like type-1 interferons, display significant anti-viral activity. In order to understand their function in more depth, we have examined the ability of IFN-lambda1/IL-29 to regulate cytokine production by human immune cells. Whole peripheral blood mononuclear cells (PBMC) exposed to IFN-lambda1 specifically upregulated IL-6, -8 and -10 but there were no visible effects on TNF or IL-1. This response was produced in a dose-dependant fashion and was inhibited by IL-10. Examination of purified cell populations isolated from PBMC demonstrated that monocytes, rather than lymphocytes, were the major IFN-lambda1-responsive cellular subset, producing IL-6, -8 and -10 in response to IFN-lambda1. Monocyte responses induced by low-level LPS stimulation were also synergistically enhanced by the presence of IFN-lambda1. Human macrophages were also shown to react to IFN-lambda1 similarly to monocytes, by producing the cytokines IL-6, -8 and -10. In conclusion, we have shown that IFN-lambda1, a cytokine produced in response to viral infection, activates both monocytes and macrophages producing a restricted panel of cytokines and may therefore be important in activating innate immune responses at the site of viral infection.

Functional differences between monocyte chemotactic protein-1 receptor A and monocyte chemotactic protein-1 receptor B expressed in a Jurkat T cell

The monocyte chemotactic protein-1 (MCP-1) receptor (MCP-1R) is expressed on monocytes, a subpopulation of memory T lymphocytes, and basophils. Two alternatively spliced forms of MCP-1R, CCR2A and CCR2B, exist and differ only in their carboxyl-terminal tails. To determine whether CCR2A and CCR2B receptors function similarly, Jurkat T cells were stably transfected with plasmids encoding the human CCR2A or CCR2B gene. Nanomolar concentrations of MCP-1 induced chemotaxis in the CCR2B transfectants that express high, intermediate, and low levels of MCP-1R. Peak chemotactic activity was shifted to the right as receptor number decreased. Five-fold more MCP-1 was required to initiate chemotaxis of the CCR2A low transfectant, but the peak of chemotaxis was similar for the CCR2A and CCR2B transfectants expressing similar numbers of receptors. MCP-1-induced chemotaxis was sensitive to pertussis toxin, implying that both CCR2A and CCR2B are G(i)alpha protein coupled. MCP-1 induced a transient Ca(2+) flux in the CCR2B transfectant that was partially sensitive to pertussis toxin. In contrast, MCP-1 did not induce Ca(2+) flux in the CCR2A transfectant. Since MCP-1 can stimulate chemotaxis of the CCR2A transfectant without inducing Ca(2+) mobilization, Ca(2+) flux may not be required for MCP-1-induced chemotaxis in the Jurkat transfectants. These results indicate that functional differences exist between the CCR2A and CCR2B transfectants that can be attributed solely to differences in the carboxyl-terminal tail.

An automated high capacity data capture and analysis system for the in vitro assessment of leukocyte adhesion under shear-stress conditions

Parallel-plate flow chambers have been used to model the vascular microcirculation and study the in vitro dynamic adhesive interactions of leukocytes and human umbilical vein endothelial cells (HUVECs). We describe here a high capacity system which can simultaneously monitor the adhesive interaction of neutrophils and HUVECs in ten flow chambers. Automated data collection was achieved with an image analyzer controlling the autostage and autofocus attachments of an inverted microscope. Images from the flow chambers were captured via phase-contrast microscopy using a video camera and laser videodisk recorder. The images were downloaded off-line into an image analyzer for automated counting of rolling and adherent cells. Neutrophils were detected by their "phase bright' characteristics. An automated optimization procedure allowed the computer to choose the best setting for the selective detection of neutrophils. In addition, a method which utilized image averaging was used to distinguish between rolling and adherent cells. A comparison of the results obtained from the manual and automated counting methods revealed linear relationships for the counting of both adherent (r = 0.98) and rolling cells (r = 0.96) with counting efficiencies of 59% and 46%, respectively. The utility of the system was demonstrated by its ability to measure the adhesive interaction between neutrophils and HUVEC in response to stimulus such as interleukin-1 alpha (IL-1 alpha), histamine, or formyl-1-methionyl-1-leucyl-1-phenylalanine (fMLP). In conclusion, we have developed an automated assay which combines the capacity of ten flow chambers with a computerized data analysis system; the result is an efficient and reproducible assay which minimizes operator associated errors and biological variability.

Roles of adenosine and theophylline on the recovery of adenine nucleotides in postischemic cultured renal tubular cells

The effect of adenosine (ADO) on the recovery of cellular adenine nucleotides (AN) was evaluated in the cultured cells deprived of oxygen and substrates (ischemia) and in nonischemic cells (control). The primary cultured cells were obtained from microdissected rabbit proximal straight tubules. Ten-day-old cultured cells were made ischemic for 6 hr, and allowed to recover for 24 hr. At the end of ischemia, cells were incubated with ADO, theophylline (T), dipyridamole (D), coformycin (C) or combined agents for 3 hr. Total AN (TAN) were determined after 3 and 24 hr of recovery. The results, after 3 hr of incubation, suggest that in both control and ischemic cells, ADO is taken up by cultured cells and is preferentially converted to nucleotides. This effect is blocked by D, which inhibits ADO uptake, uninfluenced by C, which inhibits ADO deaminase and potentiated by T, which inhibits 5'-nucleotidase. After 24 hr of recovery, the beneficial effects of ADO alone or combined D, C, or T, on TAN were not seen in control cells. In contrast, in the ischemic cells, after 24 hr of recovery, ADO + T normalized ATP, ADP and TAN to the preischemic levels. T alone significantly increased ATP after 24 hr of recovery. To demonstrate further that the beneficial effect of T is due to inhibition of 5'-nucleotidase, cells were treated with adenosine alpha, beta-methylene diphosphate in the same manner as T. Combined ADO + adenosine alpha, beta-methylene diphosphate normalized ATP, ADP and TAN after 24 hr of recovery. This finding suggests that inhibition of 5'-nucleotidase improves postischemic AN.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of adrenoceptors in diphenylhydantoin-stimulated renin release

We have previously shown that diphenylhydantoin (DPH)-stimulated renin release is mediated by, or requires the presence of, the renal nerves. In the present study, we examined the effects of adrenergic blockers in DPH-stimulated renin release in five groups of anesthetized dogs. In vehicle-treated dogs, DPH at a dose of 0.18 mg/kg-min increased renin secretion rate (RSR) from 56 +/- 14 to 269 +/- 60 and returned to 84 +/- 30 ng of angiotensin (ANG) l/hr-min (P less than 0.01, analysis of variance). In metoprolol-treated dogs, DPH produced no significant changes in RSR (90 +/- 28 to 144 +/- 67 to 100 +/- 51 ng of ANG l/hr-min). Likewise, in atenolol-treated dogs, RSR was 34 +/- 10 before, 59 +/- 15 during, and 23 +/- 8 ng of ANG l/hr-min after the infusion of DPH. In contrast, after pretreatment with ICI 118,551 (a beta 2 adrenoceptor antagonist), RSR was 37 +/- 9 before, 151 +/- 57 during, and 47 +/- 12 ng of ANG l/hr-min after the infusion of DPH (P less than 0.01). In phentolamine-treated dogs, RSR was 69 +/- 20 before, 295 +/- 53 during, and 95 +/- 17 ng of ANG l/hr-min after the infusion of DPH (P less than 0.01). Changes in renal blood flow, renal vascular resistance, and UNa V were in the same directions in all groups. These data suggest that DPH-stimulated renin release is mediated by beta 1 adrenoceptors since both beta 2 and alpha adrenoceptor antagonists have no effects on DPH-stimulated renin release.

Role of intracellular calcium in renal nerve-mediated renin release

We evaluated the role of intracellular calcium in renal nerve-mediated renin release in four groups of anesthetized dogs. Each dog received renal nerve stimulation (RNS)(0.5 Hz) twice as follow: control, RNS, recovery; control, RNS, recovery. Group 1 served as time control. Group 2 received Ca ionophore A23187 (Io) and Groups 3 and 4 received verapamil at 2.5 and 5 micrograms/kg X min respectively during the second RNS. In Group 1, renin secretion rate (RSR) increased from 95 +/- 22 to 223 +/- 73 (P less than 0.05) and from 13 +/- 5 to 108 +/- 20 ngANG I/hr X min (P less than 0.005) during the first and second RNS, respectively. In Group 2, RSR increased from 210 +/- 85 to 402 +/- 118 (P less than 0.02) and from 88 +/- 11 to 157 +/- 39 ngANG I/hr X min (NS) during the first and second RNS, respectively. In both groups, systemic and renal hemodynamics and UNaV did not change. In Group 3, verapamil alone did not increase RSR. During RNS, RSR also did not increase. In Group 4, verapamil alone increased RSR from 42 +/- 12 to 273 +/- 71 ngANG I/hr X min (P less than 0.03) despite a similar reduction in systemic blood pressure as in Group 3. RNS did not increase RSR further during verapamil infusion. The present study suggests that increased intracellular Ca by Io inhibits renal nerve-mediated renin release. A low dose of verapamil has no effect on renin release and does not augment renal nerve-mediated renin release. A high dose of verapamil increases renin release but does not enhance RNS-mediated renin release. We conclude that intracellular calcium plays an important role in renin release and may be the final messenger in renal nerve-mediated renin release.