Angiogenesis in wound healing

During wound healing, angiogenic capillary sprouts invade the fibrin/fibronectin-rich wound clot and within a few days organize into a microvascular network throughout the granulation tissue. As collagen accumulates in the granulation tissue to produce scar, the density of blood vessels diminishes. A dynamic interaction occurs among endothelial cells, angiogenic cytokines, such as FGF, VEGF, TGF-beta, angiopoietin, and mast cell tryptase, and the extracellular matrix (ECM) environment. Specific endothelial cell ECM receptors are critical for these morphogenetic changes in blood vessels during wound repair. In particular, alpha(v)beta3, the integrin receptor for fibrin and fibronectin, appears to be required for wound angiogenesis: alpha(v)beta3 is expressed on the tips of angiogenic capillary sprouts invading the wound clot, and functional inhibitors of alpha(v)beta3 transiently inhibit granulation tissue formation. Recent investigations have shown that the wound ECM can regulate angiogenesis in part by modulating integrin receptor expression. mRNA levels of alpha(v)beta3 in human dermal microvascular endothelial cells either plated on fibronectin or overlaid by fibrin gel were higher than in cells plated on collagen or overlaid by collagen gel. Wound angiogenesis also appears to be regulated by endothelial cell interaction with the specific three-dimensional ECM environment in the wound space. In an in vitro model of human sprout angiogenesis, three-dimensional fibrin gel, simulating early wound clot, but not collagen gel, simulating late granulation tissue, supported capillary sprout formation. Understanding the molecular mechanisms that regulate wound angiogenesis, particularly how ECM modulates ECM receptor and angiogenic factor requirements, may provide new approaches for treating chronic wounds.

Receptor-associated Mad homologues synergize as effectors of the TGF-beta response

Transforming growth factor-beta TGF-beta is the prototype for a family of extracellular proteins that affect cell proliferation and tissue differentiation. TGF-beta-related factors, including BMP-2/4, Dpp and activin, act through two types of serine/threonine kinase receptors which can form a heteromeric complex. However, the mechanism of signal transduction by these receptors is largely unknown. In Drosophila, Mad is required for signalling by Dpp. We have isolated complementary DNAs for four human Mad homologues, one of which, hMAD-4, is identical to DPC-4, a candidate tumour suppressor. hMAD-3 and -4 synergized to induce strong ligand-independent TGF-beta-like responses. When truncated at their carboxy termini, hMAD-3 and -4 act as dominant-negative inhibitors of the normal TGF-beta response. The activity of hMAD-3 and -4 was regulated by the TGF-beta receptors, and hMAD-3 but not hMAD-4 was phosphorylated and associated with the ligand-bound receptor complex. These results define hMAD-3 and -4 as effectors of the TGF-beta response and demonstrate a function for DPCA-4/hMAD-4 as a tumour suppressor.

Mice lacking beta3 integrins are osteosclerotic because of dysfunctional osteoclasts

Osteoclasts express the alphavbeta3 integrin, an adhesion receptor that has been implicated in bone resorption and that is therefore a potential therapeutic target. To assess the role of this heterodimer in skeletal development in vivo, we engineered mice in which the gene for the beta3 integrin subunit was deleted. Bone marrow macrophages derived from these mutants differentiate in vitro into numerous osteoclasts, thus establishing that alphavbeta3 is not necessary for osteoclast recruitment. Furthermore, the closely related integrin, alphavbeta5, does not substitute for alphavbeta3 during cytokine stimulation or authentic osteoclastogenesis. beta3 knockout mice, but not their heterozygous littermates, develop histologically and radiographically evident osteosclerosis with age. Despite their increased bone mass, beta3-null mice contain 3.5-fold more osteoclasts than do heterozygotes. These mutant osteoclasts are, however, dysfunctional, as evidenced by their reduced ability to resorb whale dentin in vitro and the significant hypocalcemia seen in the knockout mice. The resorptive defect in beta3-deficient osteoclasts may reflect absence of matrix-derived intracellular signals, since their cytoskeleton is distinctly abnormal and they fail to spread in vitro, to form actin rings ex vivo, or to form normal ruffled membranes in vivo. Thus, although it is not required for osteoclastogenesis, the integrin alphavbeta3 is essential for normal osteoclast function.

DNA methylation represses transcription in vivo

DNA in somatic tissue is characterized by a bimodal pattern of methylation, which is established in the animal through a series of developmental events. In the mouse blastula, most DNA is unmethylated, but after implantation a wave of de novo methylation modifies most of the genome, excluding the majority of CpG islands, which are mainly associated with housekeeping genes. This genomic methylation pattern is broadly maintained during the life of the organism by maintenance methylation, and generally correlates with gene expression. Experiments both in vitro and in vivo indicate that methylation inhibits transcription. It has not yet been possible, however, to determine the role of DNA methylation on specific sequences during normal development. Cis-acting regulatory elements and trans-acting factors appear to be involved in both stage- and tissue-specific demethylation processes. Sp1-like elements have a key role in protecting the CpG island of Aprt (encoding adenine phosphoribosyltransferase) from de novo methylation, and when these elements are specifically mutated, the Aprt CpG island becomes methylated in transgenic mice. We have now characterized an embryo-specific element from the CpG island sequence upstream of Aprt that can protect itself from de novo methylation in transgenic mice as well as reduce methylation of flanking sequences. We placed this element on a removable cassette adjacent to a human HBB (encoding beta-globin) reporter and generated a transgene whose methylation pattern can be switched in vivo. Analysis of globin transcription in this system showed that methylation in cis inhibits gene expression in a variety of tissues, indicating that DNA modification may serve as a global genomic repressor.

Genomic and enzymatic evidence for acetogenesis among multiple lineages of the archaeal phylum Bathyarchaeota widespread in marine sediments

Members of the archaeal phylum Bathyarchaeota are widespread and abundant in the energy-deficient marine subsurface sediments. However, their life strategies have remained largely elusive. Here, we provide genetic evidence that some lineages of Bathyarchaeota are acetogens, being capable of homoacetogenesis, a metabolism so far restricted to the domain Bacteria. Metabolic reconstruction based on genomic bins assembled from the metagenome of deep-sea subsurface sediments shows that the metabolism of some lineages of Bathyarchaeota is similar to that of bona fide bacterial homoacetogens, by having pathways for acetogenesis and for the fermentative utilization of a variety of organic substrates. Heterologous expression and activity assay of the acetate kinase gene ack from Bathyarchaeota, demonstrate further the capability of these Bathyarchaeota to grow as acetogens. The presence and expression of bathyarchaeotal genes indicative of active acetogenesis was also confirmed in Peru Margin subsurface sediments where Bathyarchaeota are abundant. The analyses reveal that this ubiquitous and abundant subsurface archaeal group has adopted a versatile life strategy to make a living under energy-limiting conditions. These findings further expand the metabolic potential of Archaea and argue for a revision of the role of Archaea in the carbon cycle of marine sediments.

Thyroid hormone regulation of hepatic genes in vivo detected by complementary DNA microarray

The liver is an important target organ of thyroid hormone. However, only a limited number of hepatic target genes have been identified, and little is known about the pattern of their regulation by thyroid hormone. We used a quantitative fluorescent cDNA microarray to identify novel hepatic genes regulated by thyroid hormone. Fluorescent-labeled cDNA prepared from hepatic RNA of T3-treated and hypothyroid mice was hybridized to a cDNA microarray, representing 2225 different mouse genes, followed by computer analysis to compare relative changes in gene expression. Fifty five genes, 45 not previously known to be thyroid hormone-responsive genes, were found to be regulated by thyroid hormone. Among them, 14 were positively regulated by thyroid hormone, and unexpectedly, 41 were negatively regulated. The expression of 8 of these genes was confirmed by Northern blot analyses. Thyroid hormone affected gene expression for a diverse range of cellular pathways and functions, including gluconeogenesis, lipogenesis, insulin signaling, adenylate cyclase signaling, cell proliferation, and apoptosis. This is the first application of the microarray technique to study hormonal regulation of gene expression in vivo and should prove to be a powerful tool for future studies of hormone and drug action.

SAR650984 directly induces multiple myeloma cell death via lysosomal-associated and apoptotic pathways, which is further enhanced by pomalidomide

The anti-CD38 monoclonal antibody SAR650984 (SAR) is showing promising clinical activity in treatment of relapsed and refractory multiple myeloma (MM). Besides effector-mediated antibody-dependent cellular cytotoxicity and complement-mediated cytotoxicity, we here define molecular mechanisms of SAR-directed MM cell death and enhanced anti-MM activity triggered by SAR with Pomalidomide (Pom). Without Fc-cross-linking agents or effector cells, SAR specifically induces homotypic aggregation (HA)-associated cell death in MM cells dependent on the level of cell surface CD38 expression, actin cytoskeleton and membrane lipid raft. SAR and its F(ab)'2 fragments trigger caspase 3/7-dependent apoptosis in MM cells highly expressing CD38, even with p53 mutation. Importantly, SAR specifically induces lysosome-dependent cell death (LCD) by enlarging lysosomes and increasing lysosomal membrane permeabilization associated with leakage of cathepsin B and LAMP-1, regardless of the presence of interleukin-6 or bone marrow stromal cells. Conversely, the lysosomal vacuolar H+-ATPase inhibitor blocks SAR-induced LCD. SAR further upregulates reactive oxygen species. Pom enhances SAR-induced direct and indirect killing even in MM cells resistant to Pom/Len. Taken together, SAR is the first therapeutic monoclonal antibody mediating direct cytotoxicity against MM cells via multiple mechanisms of action. Our data show that Pom augments both direct and effector cell-mediated MM cytotoxicity of SAR, providing the framework for combination clinical trials.

Cancer-FOXP3 directly activated CCL5 to recruit FOXP3+Treg cells in pancreatic ductal adenocarcinoma

Forkheadbox protein 3 (FOXP3), initially identified as a key transcription factor for regulatory T cells (Treg cells), was also expressed in many tumors including pancreatic ductal adenocarcinoma (PDAC). However, its role in PDAC progression remains elusive. In this study, we utilized 120 PDAC tissues after radical resection to detect cancer-FOXP3 and Treg cells by immunohistochemistry and evaluated clinical and pathological features of these patients. Cancer-FOXP3 was positively correlated with Treg cells accumulation in tumor tissues derived from PDAC patients. In addition, high cancer-FOXP3 expression was associated with increased tumor volumes and poor prognosis in PDAC especially combined with high levels of Treg cells. Overexpression of cancer-FOXP3 promoted the tumor growth in immunocompetent syngeneic mice but not in immunocompromised or Treg cell-depleted mice. Furthermore, CCL5 was directly trans-activated by cancer-FOXP3 and promoted the recruitment of Treg cells from peripheral blood to the tumor site in vitro and in vivo. This finding has been further reinforced by the evidence that Treg cells recruitment by cancer-FOXP3 was impaired by neutralization of CCL5, thereby inhibiting the growth of PDAC. In conclusion, cancer-FOXP3 serves as a prognostic biomarker and a crucial determinant of immunosuppressive microenvironment via recruiting Treg cells by directly trans-activating CCL5. Therefore, cancer-FOXP3 could be used to select patients with better response to CCL5/CCR5 blockade immunotherapy.

Receptor-interacting protein kinase 3 is a predictor of survival and plays a tumor suppressive role in colorectal cancer

Receptor-interacting protein kinase 3 (RIP3) is a member of the RIP Ser/Thr kinase family, plays an important role in regulating cell survival, cell apoptosis and cell necrosis. However, the role of RIP3 in the carcinogenesis of colorectal cancer is still poorly understood.We used quantitative PCR and Western blot analysis to examine RIP3 expression in primary colorectal cancer and paired normal colorectal mucosa. RIP3 clinicopathological significance was assessed by immunohistochemical staining in 112 cases of primary colorectal cancer paired with noncancerous tissues. The biological function of RIP3 overexpression was measured by CCK8 assay and plate colony formation assay. Dual staining with fluorescent Annexin V and propidium iodide (PI) was used to discriminate apoptotic or necrotic cell death.RIP3 expression was significantly lower in colorectal cancer and associated with T stage, M stage and AJCC stage. Cox proportional hazard models showed that RIP3 expression was an independent prognostic factor for overall survival and disease-free survival in patients with colorectal cancer. Overexpression of RIP3 significantly suppressed the proliferation of colorectal cancer cells in vitro.Our results suggest that RIP3 may function as a novel prognostic indicator after surgery and play a suppressive role in the colorectal carcinogenesis.

gC1q-R/p33, a member of a new class of multifunctional and multicompartmental cellular proteins, is involved in inflammation and infection

Human gC1q-R (p33, p32, C1qBP, TAP) is a ubiquitously expressed, multiligand-binding, multicompartmental cellular protein involved in various ligand-mediated cellular responses. Although expressed on the surface of cells, an intriguing feature of the membrane-associated form of gC1q-R is that its translated amino acid sequence does not predict the presence of either a sequence motif compatible with a transmembrane segment or a consensus site for a glycosylphosphatidylinositol anchor. Moreover, the N-terminal sequence of the pre-pro-protein gC1q-R contains a motif that targets the molecule to the mitochondria and as such was deemed unlikely to be expressed on the surface. However, several lines of experimental evidence clearly show that gC1q-R is present in all compartments of the cell, including the extracellular cell surface. First, surface labeling of B lymphocytes with the membrane-impermeable reagent sulfosuccinimidyl 6-(biotinamido)hexanoate shows specific biotin incorporation into the surface-expressed but not the intracellular form of gC1q-R. Second, FACS and confocal laser scanning microscopic analyses using anti-gC1q-R IgG mAb 60.11 or 74.5.2, and the fluorophore Alexa 488-conjugated F(ab')2 goat anti-mouse IgG as a probe, demonstrated specific staining of Raji cells (>95% viable). Three-dimensional analyses of the same cells by confocal microscopy showed staining distribution that was consistent with surface expression. Third, endothelial gC1q-R, which is associated with the urokinase plasminogen activator receptor, and cytokeratin 1 bind 125I-high molecular weight kininogen in a specific manner, and the binding is inhibited dose-dependently by mAb 74.5.2 recognizing gC1q-R residues 204-218. Fourth, native gC1q-R purified from Raji cell membranes but not intracellular gC1q-R is glycosylated, as evidenced by a positive periodic acid Schiff stain as well as sensitivity to digestion with endoglycosidase H and F. Finally, cross-linking experiments using C1q as a ligand indicate that both cC1q-R and gC1q-R are co-immunoprecipitated with anti-C1q. Taken together, the evidence accumulated to date supports the concept that in addition to its intracellular localization, gC1q-R is expressed on the cell surface and can serve as a binding site for plasma and microbial proteins, but also challenges the existing paradigm that mitochondrial proteins never leave their designated compartment. It is therefore proposed that gC1q-R belongs to a growing list of a class of proteins initially targeted to the mitochondria but then exported to different compartments of the cell through specific mechanisms which have yet to be identified. The designation 'multifunctional and multicompartmental cellular proteins' is proposed for this class of proteins.

A Glanzmann's mutation in beta 3 integrin specifically impairs osteoclast function

Osteoclastic bone resorption requires cell-matrix contact, an event mediated by the alpha v beta 3 integrin. The structural components of the integrin that mediate osteoclast function are, however, not in hand. To address this issue, we generated mice lacking the beta 3 integrin gene, which have dysfunctional osteoclasts. Here, we show the full rescue of beta 3(-/-) osteoclast function following expression of a full-length beta 3 integrin. In contrast, truncated beta 3, lacking a cytoplasmic domain (h beta 3c), is completely ineffective in restoring function to beta 3(-/-) osteoclasts. To identify the components of the beta 3 cytoplasmic domain regulating osteoclast function, we generated six point mutants known, in other circumstances, to mediate beta integrin signaling. Of the six, only the S(752)P substitution, which also characterizes a form of the human bleeding disorder Glanzmann's thrombasthenia, fails to rescue beta 3(-/-) osteoclasts or restore ligand-activated signaling in the form of c-src activation. Interestingly, the double mutation Y(747)F/Y(759)F, which disrupts platelet function, does not affect the osteoclast. Thus similarities and distinctions exist in the mechanisms by which the beta 3 integrin regulates platelets and osteoclasts.

Electronic structure of spatially aligned graphene nanoribbons on Au(788)

We report on a bottom-up approach of the selective and precise growth of subnanometer wide straight and chevron-type armchair nanoribbons (GNRs) on a stepped Au(788) surface using different specific molecular precursors. This process creates spatially well-aligned GNRs, as characterized by STM. High-resolution direct and inverse photoemission spectroscopy of occupied and unoccupied states allows the determination of the energetic position and momentum dispersion of electronic states revealing the existence of band gaps of several electron volts for straight 7-armchair, 13-armchair, and chevron-type GNRs in the electronic structure.

Interleukin-6 is both necessary and sufficient to produce perioperative neurocognitive disorder in mice

BACKGROUND

Perioperative neurocognitive disorders (PND) result in long-term morbidity and mortality with no effective interventions available. Because interleukin-6 (IL-6), a pro-inflammatory cytokine, is consistently up-regulated by trauma, including after surgery, we determined whether IL-6 is a putative therapeutic target for PND in a mouse model.

METHODS

Following institutional approval, adult (12-14 weeks) male C57/Bl6 mice were pretreated with the IL-6 receptor (IL6R) blocking antibody tocilizumab prior to open tibia fracture with internal fixation under isoflurane anaesthesia. Inflammatory and behavioural responses in a trace fear conditioning (TFC) paradigm were assessed postoperatively. Separately, the effects of IL-6 administration or of depletion of bone marrow-derived monocytes (BM-DMs) with clodrolip on the inflammatory and behavioural responses were assessed. Blood brain barrier disruption, hippocampal microglial activation, and infiltration of BM-DMs were each assessed following IL-6 administration.

RESULTS

The surgery-induced decrement in freezing time in the TFC assay, indicative of cognitive decline, was attenuated by tocilizumab (P<0.01). The surgery-induced increase in pro-inflammatory mediators was significantly reduced by tocilizumab. Exogenously administered IL-6 significantly impaired freezing behaviour (P<0.05) and up-regulated pro-inflammatory cytokines; both responses were prevented by depletion of BM-DMs. IL-6 disrupted the blood brain barrier, and increased hippocampal activation of microglia and infiltration of BM-DMs.

CONCLUSIONS

IL-6 is both necessary and sufficient to produce cognitive decline. Following further preclinical testing of its perioperative safety, the IL6R blocker tocilizumab is a candidate for prevention and/or treatment of PND.

Necroptosis inhibitor necrostatin-1 promotes cell protection and physiological function in traumatic spinal cord injury

Spinal cord injury (SCI) is a common and serious trauma which lacks efficient treatment. Inhibition of cell death in the trauma area is important for spinal cord protection during this process. In this study, necroptosis inhibitor necrostatin-1 (Nec-1) was used to treat SCI rats, to investigate the role of Nec-1 in the recovery of SCI. Nec-1 was found to reduce lesions, cytokines and reactive oxygen species (ROS), improve pathological conditions and blood supply in the spinal cord trauma area. Further study indicated that Nec-1 could inhibit necroptosis by inhibiting RIP1/3-MLKL recruitment and inhibit apoptosis by inhibiting Caspase 3 and Bax while activating Bcl-2. Ethological performance of SCI rats confirmed improvement and protection of physiological function by Nec-1. Nec-1 as a potential treatment for SCI warrants further study. To our knowledge, this is the first study on the role of Nec-1 in the treatment of traumatic SCI. Our research also found inhibition effects of Nec-1 on apoptosis, not only necroptosis - as reported by most publications.

Transplantation of umbilical cord mesenchymal stem cells alleviates lupus nephritis in MRL/lpr mice

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease, which, despite the advances in immunosuppressive medical therapies, remains potentially fatal in some patients, especially in treatment-refractory patients. This study found that transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) has the same therapeutic effect as transplantation of bone marrow mesenchymal stem cells (BM-MSCs), which has been reported to be efficient in treating SLE-related symptoms in MRL/lpr mice. Multi-treatment (at the 18th, 19th, and 20th weeks of age) of 1 × 10(6) UC-MSCs was able to decrease the levels of 24-h proteinuria, serum creatinine, and anti-double-stranded DNA (dsDNA) antibody, and the extent of renal injury such as crescent formation in MRL/lpr mice. A lower, but still significant, reduction in these parameters was also observed in mice receiving a single dose of UC-MSCs (at the 18th week). UC-MSCs treatment also inhibited expression of monocyte chemotactic protein-1 (MCP-1) and high-mobility group box 1 (HMGB-1) expression in a similar fashion. UC-MSCs labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE) were found in the lungs and kidneys 1 week post infusion. In addition, after 11 weeks post UC-MSCs infusion, human cells were found in kidney of UC-MSCs-treated mice. These findings indicated that UC-MSCs transplantation might be a potentially promising approach in the treatment of lupus nephritis, possibly by inhibiting MCP-1 and HMGB-1 production.

Climatic Implications of an 8000-Year Hydrogen Isotope Time Series from Bristlecone Pine Trees

Tree rings from three dendrochronologically dated bristlecone pines were analyzed for stable hydrogen isotopic composition. These trees give a continuous time series from 8000 years ago to the present that indicates the presence of a postglacial climate optimum 6800 years ago and a continuous cooling since then. The qualitative agreement between this record and records from other sources, such as ice cores, pollen, and treeline fluctuations, indicates that these climate changes were global. This record can serve as a reference for other climate indicators throughout the past 8000 years.

Transforming growth factor-beta up-regulates the beta 5 integrin subunit expression via Sp1 and Smad signaling

Integrin-mediated cell-matrix interactions play important roles in regulating cell function. Since transforming growth factor-beta (TGF-beta) modulates many osteoblast activities, we hypothesized that the growth factor acts in part by modulating integrin expression. TGF-beta increased cell adhesion to vitronectin and up-regulated the surface level of alpha(v)beta(5) via increasing beta(5) protein synthesis by a transcriptional mechanism. Promoter activity analysis demonstrated that a TGF-beta-responsive element resides between nucleotides -63 and -44. Electrophoretic mobility shift assay and immunoprecipitation/Western studies indicated that the nuclear complex formed using the -66/-42 oligonucleotide contained both Sp1/Sp3 and Smad proteins. Since nuclear Sp1/Sp3 levels were not altered, whereas Smad levels were increased by TGF-beta, we investigated the roles of Smad proteins in the up-regulation of beta(5) gene activation. Co-transfection of cells with beta(5) promoter reporter construct and expression vectors for Smad3, Smad4, and Sp1 increased the stimulatory effect of TGF-beta. Furthermore, expression of dominant negative Smad3 or Smad4 in cells decreased or abolished the stimulation of beta(5) promoter activity by TGF-beta. Smad4 mutant also inhibited the up-regulation of surface beta(5) level by TGF-beta. Thus, TGF-beta increases expression of the integrin beta(5) gene by mechanisms involving Sp1/Sp3 and Smad transcription factors.

Visualization of dynamic trafficking of a protein kinase C betaII/green fluorescent protein conjugate reveals differences in G protein-coupled receptor activation and desensitization

Protein kinase C (PKC) links various extracellular signals to intracellular responses and is activated by diverse intracellular factors including diacylglycerol, Ca2+, and arachidonic acid. In this study, using a fully functional green fluorescent protein conjugated PKCbetaII (GFP-PKCbetaII), we demonstrate a novel approach to study the dynamic redistribution of PKC in live cells in response to G protein-coupled receptor activation. Agonist-induced PKC translocation was rapid, transient, and selectively mediated by the activation of Gqalpha- but not Gsalpha- or Gialpha-coupled receptors. Interestingly, although the stimuli were continuously present, only one brief peak of PKC membrane translocation was observed, consistent with rapid desensitization of the signaling pathway. Moreover, when GFP-PKCbetaII was used to examine cross-talk between two Gqalpha-coupled receptors, angiotensin II type 1A receptor (AT1AR) and endothelin A receptor (ETAR), activation of ETARs resulted in a subsequent loss of AT1AR responsiveness, whereas stimulation of AT1ARs did not cause desensitization of the ETAR signaling. The development of GFP-PKCbetaII has allowed not only the real time visualization of the dynamic PKC trafficking in live cells in response to physiological stimuli but has also provided a direct and sensitive means in the assessment of activation and desensitization of receptors implicated in the phospholipase C signaling pathway.