Gating function of isoleucine-116 in TM-3 (position III:16/3.40) for the activity state of the CC-chemokine receptor 5 (CCR5)

BACKGROUND AND PURPOSE

A conserved amino acid within a protein family indicates a significance of the residue. In the centre of transmembrane helix (TM)-5, position V:13/5.47, an aromatic amino acid is conserved among class A 7TM receptors. However, in 37% of chemokine receptors - a subgroup of 7TM receptors - it is a leucine indicating an altered function. Here, we describe the significance of this position and its possible interaction with TM-3 for CCR5 activity.

EXPERIMENTAL APPROACH

The effects of [L203F]-CCR5 in TM-5 (position V:13/5.47), [I116A]-CCR5 in TM-3 (III:16/3.40) and [L203F;G286F]-CCR5 (V:13/5.47;VII:09/7.42) were determined in G-protein- and β-arrestin-coupled signalling. Computational modelling monitored changes in amino acid conformation.

KEY RESULTS

[L203F]-CCR5 increased the basal level of G-protein coupling (20-70% of Emax ) and β-arrestin recruitment (50% of Emax ) with a threefold increase in agonist potency. In silico, [I116A]-CCR5 switched χ1-angle in [L203F]-CCR5. Furthermore, [I116A]-CCR5 was constitutively active to a similar degree as [L203F]-CCR5. Tyr(244) in TM-6 (VI:09/6.44) moved towards TM-5 in silico, consistent with its previously shown function for CCR5 activation. On [L203F;G286F]-CCR5 the antagonist aplaviroc was converted to a superagonist.

CONCLUSIONS AND IMPLICATIONS

The results imply that an aromatic amino acid in the centre of TM-5 controls the level of receptor activity. Furthermore, Ile(116) acts as a gate for the movement of Tyr(244) towards TM-5 in the active state, a mechanism proposed previously for the β2 -adrenoceptor. The results provide an understanding of chemokine receptor function and thereby information for the development of biased and non-biased antagonists and inverse agonists.

Spinal presynaptic inhibition in pain control

The gate control theory proposed that the nociceptive sensory information transmitted to the brain relies on an interplay between the inputs from nociceptive and non-nociceptive primary afferent fibers. Both inputs are normally under strong inhibitory control in the spinal cord. Under healthy conditions, presynaptic inhibition activated by non-nociceptive fibers modulates the afferent input from nociceptive fibers onto spinal cord neurons, while postsynaptic inhibition controls the excitability of dorsal horn neurons, and silences the non-nociceptive information flow to nociceptive-specific (NS) projection neurons. However, under pathological conditions, this spinal inhibition may be altered and lead to chronic pain. This review summarizes our knowledge of presynaptic inhibition in pain control, with particular focus on how its alteration after nerve or tissue injury contributes to neuropathic or inflammatory pain syndromes, respectively.

Expression of insulin-like growth factor-1 receptor in keloid and hypertrophic scar

BACKGROUND

Keloid and hypertrophic scar (HS) are two pathological forms of excessive dermal fibrosis, which are due to aberrant wound-healing responses. Accumulating evidence suggests that aberrant activity of growth factors and increased numbers of growth factor receptors play an important role in the formation of pathological scar.

AIM

We examined the expression level of insulin-like growth factor-1 receptor (IGF-IR) in keloid, HS and normal skin.

METHODS

IGF-IR expression was analyzed by immunohistochemistry, real-time PCR and western blotting on tissues and fibroblasts from 30 patients, comprising 10 patients with keloid and 20 with HS (10 with immature and 10 with mature HS), and from 10 age-matched and sex-matched healthy controls.

RESULTS

Immunoreactivity to IGF-IR was found in dermal fibroblasts of keloid (90%), immature HS, (80%) and mature HS (30%), but not in normal skin. There was no statistically significant difference in immunoreactivity scores between keloid and immature HS, but there was a significant difference (P < 0.01) between mature and immature HS. Real-time PCR and western blot analysis confirmed that there was high expression of IGF-IR in keloid and immature HS fibroblasts, but not in mature HS or normal skin fibroblasts. IGF-IR was expressed in the overlying epidermis, and there was no significant difference between the groups.

CONCLUSIONS

IGF-IR may be involved in the pathogenesis of keloid and HS. Given that IGF-IR are predominantly expressed on dermal fibroblasts, targeting of IGF-IR in fibroblasts may be of benefit to prevent scarring.

Growth and viability of Liaoning Cashmere goat hair follicles during the annual hair follicle cycle

Here, we studied hair follicle development of Liaoning Cashmere goats. Every month for 1 year, skin samples were collected from five 1.5-year-old female goats, and made into paraffin sections. A number of parameters were measured of primary and secondary hair follicles via microscopic observation including follicle depth, hair bulb width, dermis and epidermis thickness, changes in follicle activity, and histology. The results showed the presence of three phases in the annual hair cycle: anagen, catagen, and telogen. Primary and secondary hair follicle depth varied across the months; however, no significant difference was obtained between adjacent months (P>0.05). Primary hair follicles had a bigger hair bulb width compared to secondary hair follicles; however, this difference declined during hair follicle developed in anagen. As hair follicle growth slowed, the hair bulb broadened, and hair root depth became shallower. During the entire hair cycle, hair follicle depth and dermis thickness were positively correlated; however, this relationship was not significant (P>0.05) for primary and secondary hair follicle density and the ratio of secondary hair follicle density and primary hair follicle density (S/P ratio). In addition, new and old primary hair follicles coexisted with secondary hair follicles. Finally, secondary hair follicles had a higher activity rate compared to primary hair follicle in adult Liaoning Cashmere goats in certain months.

Metal vapor target for precise studies of ion-atom collisions

Although different ion-atom collisions have been studied in various contexts, precise values of cross-sections for many atomic processes were seldom obtained. One of the main uncertainties originates from the value of target densities. In this paper, we describe a unique method to measure a target density precisely with a combination of physical vapor deposition and inductively coupled plasma optical emission spectrometry. This method is preliminarily applied to a charge transfer cross-section measurement in collisions between highly charged ions and magnesium vapor. The final relative uncertainty of the target density is less than 2.5%. This enables the precise studies of atomic processes in ion-atom collisions, even though in the trial test the deduction of precise capture cross-sections was limited by other systematic errors.

Conversion of differentiated cancer cells into cancer stem-like cells in a glioblastoma model after primary chemotherapy

Glioblastoma multiforme patients have a poor prognosis due to therapeutic resistance and tumor relapse. It has been suggested that gliomas are driven by a rare subset of tumor cells known as glioma stem cells (GSCs). This hypothesis states that only a few GSCs are able to divide, differentiate, and initiate a new tumor. It has also been shown that this subpopulation is more resistant to conventional therapies than its differentiated counterpart. In order to understand glioma recurrence post therapy, we investigated the behavior of GSCs after primary chemotherapy. We first show that exposure of patient-derived as well as established glioma cell lines to therapeutic doses of temozolomide (TMZ), the most commonly used antiglioma chemotherapy, consistently increases the GSC pool over time both in vitro and in vivo. Secondly, lineage-tracing analysis of the expanded GSC pool suggests that such amplification is a result of a phenotypic shift in the non-GSC population to a GSC-like state in the presence of TMZ. The newly converted GSC population expresses markers associated with pluripotency and stemness, such as CD133, SOX2, Oct4, and Nestin. Furthermore, we show that intracranial implantation of the newly converted GSCs in nude mice results in a more efficient grafting and invasive phenotype. Taken together, these findings provide the first evidence that glioma cells exposed to chemotherapeutic agents are able to interconvert between non-GSCs and GSCs, thereby replenishing the original tumor population, leading to a more infiltrative phenotype and enhanced chemoresistance. This may represent a potential mechanism for therapeutic relapse.

In vitro and in vivo studies of antitumor effects of the recombinant immunotoxin MSH-PE38KDEL on melanoma

MSH-PE38KDEL is a chimeric molecule composed of MSH, and fused to a truncated mutant form of Pseudomonas exotoxin (PE38KDEL). Our study aims to evaluate the specific cytotoxicity of recombinant immunotoxin MSH-PE38KDEL on melanoma cells A875 and B16 in vitro, as well as its inhibition of metastatic melanoma in vivo. MSH-PE38KDEL was expressed in Escherichia coli, and greater than 90% purity was obtained. The purified MSH-PE38KDEL was found to be selectively cytotoxic to MSH receptor-positive melanoma cells in vitro. The specific cytotoxicity of recombinant MSH-PE38KDEL to A875 and B16 was over 85% by cell viability assay; however, MSH-PE38KDEL had no cytotoxicity to the human 2BS cells. The anti-tumor activity of MSH-PE38KDEL was evaluated in mice with induced melanoma through intra-tumor or intravenous administration. The results showed that 90% melanoma growths were inhibited, and 40% of the tumors were disappeared completely. Histopathology results showed MSH-PE38KDEL can effectively inhibit intrahepatic metastasis. In conclusion, MSH-PE38KDEL had cytotoxic effects on MSH receptor-positive melanoma cells, and causes significant tumor growth inhibition. These results support a possible new approach for the treatment of melanoma.

Increased expression of α5β1-integrin is a prognostic marker for patients with gastric cancer

OBJECTIVE

The study was to evaluate the association of expression level of α5β1-integrin with clinicopathologic features and prognosis in gastric cancer (GC).

METHODS

The expression of α5β1-integrin in normal gastric mucosa and GC tissue was detected with immunohistochemistry. The level of α5 and β1 mRNA in GC tissues and non-neoplastic tissues was evaluated in 48 paired cases by quantitative real-time polymerase chain reaction (qRT-PCR). Survival analysis by the Kaplan-Meier method was performed to assess prognostic significance.

RESULTS

The α5β1-integrin expression was detected in 68.3 % (127/186) GC samples, and there was a significant difference on their positive expression rate between GC tissue and normal gastric mucosa (P < 0.001). The positive expression rate of α5β1-integrin in patients with poor histologic differentiation (P = 0.001), lymph node metastasis (P < 0.001), and recurrence (P < 0.001) group was heightened. Using Kaplan-Meier analysis, a comparison of survival curves of low versus high expresser of α5β1-integrin revealed a highly significant difference in human GC tissue (P = 0.002), which suggested that overexpression of α5β1-integrin is associated with a worse prognosis. Multivariate analyses showed that α5β1-integrin expression was independent risk factor predicting overall survival [Hazard ratio (HR) 1.594, 95 % confidence interval (CI) 1.236-2.408, P = 0.006] and disease-free survival [HR 3.952, 95 % CI 1.676-9.861, P = 0.003] in GC.

CONCLUSIONS

The α5β1-integrin promotes angiogenesis and associates with lymph node metastasis, vascular invasion and poor prognosis of GC. The current study shows that α5β1-integrin may be an independent prognostic factor for GC patients.

Smooth muscle cell phenotypic diversity between dissected and unaffected thoracic aortic media

AIM

Smooth muscle cell (SMC) phenotypic switching in the aortic media may play a critical role in the pathogenesis of thoracic aortic dissection (TAD). However, few investigations are available and most of the observations are based on histological examinations without in vitro evidence. This study, which was performed both in vivo and in vitro, was designed to investigate SMC phenotypic diversity between dissected and unaffected aortic media.

METHODS

Using optimized explant technique, aortic medial SMCs were obtained from patients with TAD and controls. In vivo and in vitro expression of α-smooth muscle actin (α-SMA), smooth muscle-myosin heavy chain 2 (SM-MHC-2), smooth muscle-calponin (SM-Calponin), Vimentin, osteopontin (OPN) and non-muscle myosin heavy chain B (SMemb) were evaluated by immunostaining and immunoblotting. SMC proliferation was also analyzed.

RESULTS

Although the majority of SMCs from the dissected media displayed an elongated, spindle- or triangle-like shape as control SMCs, there were some oval or flat, quadrate cells in the dissection cultures. In contrast with controls, SMCs derived from the dissected media uniformly showed the negative staining for the contractile proteins and the intense staining for the synthetic markers. Similarly, in vitro protein levels of α-SMA, SM-MHC-2, SM-Calponin and Vimentin were significantly decreased to 60.1% (P<0.05), 12.0% (P<0.01), 23.1% (P<0.01) and 32.5% (P<0.01) respectively, whereas those of OPN and SMemb were markedly elevated by5.7- and 10.3-fold respectively (P<0.01 for both). In vivo expression of the phenotypic markers showed the parallel results. Furthermore, SMCs derived from the dissected media exhibited the enhanced proliferation (P<0.05).

CONCLUSION

We have established a simple and potent method to acquire SMCs from the dissected and unaffected aortic media. Compared to the contractile SMCs in the unaffected media, those in the dissected media manifest phenotypic switching from the contractile to the synthetic type. The primary cultures can be subsequently used as in vitro models and contribute to further elucidating the etiopathogenesis of TAD.

ER stress-mediated apoptosis induced by celastrol in cancer cells and important role of glycogen synthase kinase-3β in the signal network

HeLa cells treated with celastrol, a natural compound with inhibitive effect on proteasome, exhibited increase in apoptotic rate and characteristics of apoptosis. To clarify the signal network activated by celastrol to induce apoptosis, both the direct target proteins and undirect target proteins of celastrol were searched in the present study. Proteasome catalytic subunit β1 was predicted by computational analysis to be a possible direct target of celastrol and confirmed by checking direct effect of celastrol on the activity of recombinant human proteasome subunit β1 in vitro. Undirect target-related proteins of celastrol were searched using proteomic studies including two-dimensional electrophoresis (2-DE) analysis and iTRAQ-based LC-MS analysis. Possible target-related proteins of celastrol such as endoplasmic reticulum protein 29 (ERP29) and mitochondrial import receptor Tom22 (TOM22) were found by 2-DE analysis of total cellular protein expression profiles. Further study showed that celastrol induced ER stress and ER stress inhibitor could ameliorate cell death induced by celastrol. Celastrol induced translocation of Bax into the mitochondria, which might be related to the upregulation of BH-3-only proteins such as BIM and the increase in the expression level of TOM22. To further search possible target-related proteins of celastrol in ER and ER-related fractions, iTRAQ-based LC-MS method was use to analyze protein expression profiles of ER/microsomal vesicles-riched fraction of cells with or without celastrol treatment. Based on possible target-related proteins found in both 2-DE analysis and iTRAQ-based LC-MS analysis, protein–protein interaction (PPI) network was established using bioinformatic analysis. The important role of glycogen synthase kinase-3β (GSK3β) in the signal cascades of celastrol was suggested. Pretreatment of LiCL, an inhibitor of GSK3β, could significantly ameliorate apoptosis induced by celastrol. On the basis of the results of the present study, possible signal network of celastrol activated by celastrol leading to apoptosis was predicted.

Notch1 overexpression promotes cell growth and tumor angiogenesis in myeloma

Patients with multiple myeloma (MM) have increased bone marrow angiogenesis, but the angiogenic properties of myeloma cells and the mechanism of MM-induced angiogenesis have not been completely clarified. Notch1 signal has been identified as a critical factor in the regulation of vessel formation. However, the role of Notch1 in the angiogenesis of MM is unclear. We constitutively overexpressed active Notch1 in RPMI8226 cells to explore the effect of Notch1 signaling on cell growth and tumor angiogenesis in vivo and in vitro. We found that Notch1 overexpression promoted myeloma cells growth and increased drug resistance. Moreover, vascular endothelial growth factor (VEGF) expression was increased. Finally, our in vitro results were supported by the in vivo finding in human myeloma xenograft Nonobese diabetic/severe combined immunodeficient (NOD/SCID) models. Notch1 overexpression in MM cells resulted in up-regulation of VEGF expression, promotion of tumor growth, and increased microvessel density (MVD). Our study suggests that Notch1-induced angiogenesis is partly due to activation of VEGF pathway.

Molecular characteristics of the SLA-2 gene from Chinese Hebao pigs

To study the molecular characteristics of swine leukocyte antigen (SLA) class I from the Hebao pig, a rare inbreed in China, a pair of primers was designed to amplify the SLA-2 gene (SLA-2-HB) and then the molecular characteristics of the gene were analyzed by computer. After cloning, sequencing and computer analysis, four SLA-2-HB alleles were found, all of 1119 bp. Sites 3-1097 were an open reading frame encoding 364 amino acids with two sets of intra-chain disulfide bonds comprising four cysteines situated in sites 125, 188, 227 and 283. By alignment of SLA-2-HB sequences with other SLA-2 alleles in the DNA Data Bank of Japan/European Molecular Biology Laboratory/GenBank database, nine key variable amino acid sites were found in the extracellular domain of the SLA-2-HB alleles at sites 23(F), 24(I), 43(A), 44(K), 50(Q), 73(N), 95(I), 114(R) and 216(S), which could be used to differentiate other SLA-2 alleles. The amino acid identities between SLA-2-HB and other SLA-2, SLA-3 and SLA-1 alleles were 87.1-97.0%, 85.0-93.9% and 83.3- 88.6%, respectively. The phylogenetic tree of SLA-2-HB showed that it was relatively independent of the other SLA-2 genes. Furthermore, the SLA-2-HB alleles were similar to HLA-B15 and HLA-A2 functional do- mains and preserved some functional sites of HLA-A2. It was concluded that SLA-2-HB is an allele of SLA-2 and that the Hebao pig might have evolved independently in China.

IL-7Rα deficiency in p53null mice exacerbates thymocyte telomere erosion and lymphomagenesis

Interleukin-7 (IL-7) is an essential T-cell survival cytokine. IL-7 receptor (IL-7Rα) deficiency severely impairs T-cell development due to substantial apoptosis. We hypothesized that IL-7Rα(null)-induced apoptosis is partially contributed by an elevated p53 activity. To investigate the genetic association of IL-7/IL-7Rα signaling with the p53 pathway, we generated IL-7Rα(null)p53(null) (DKO) mice. DKO mice exhibited a marked reduction of apoptosis in developing T cells and an augmented thymic lymphomagenesis with telomere erosions and exacerbated chromosomal anomalies, including chromosome duplications, breaks, and translocations. In particular, Robertsonian translocations, in which telocentric chromosomes fuse at the centromeric region, and a complete loss of telomeres at the fusion site occurred frequently in DKO thymic lymphomas. Cellular and molecular investigations revealed that IL-7/IL-7Rα signaling withdrawal diminished the protein synthesis of protection of telomere 1 (POT1), a subunit of telomere protective complex shelterin, leading to telomere erosion and the activation of the p53 pathway. Blockade of IL-7/IL-7Rα signaling in IL-7-dependent p53(null) cells reduced POT1 expression and caused telomere and chromosome abnormalities similar to those observed in DKO lymphomas. This study underscores a novel function of IL-7/IL-7Rα during T-cell development in regulating telomere integrity via POT1 expression and provides new insights into cytokine-mediated survival signals and T-cell lymphomagenesis.