miR-542-3p suppresses osteoblast cell proliferation and differentiation, targets BMP-7 signaling and inhibits bone formation

MicroRNAs (miRNAs) are short non-coding RNAs that interfere with translation of specific target mRNAs and thereby regulate diverse biological processes. Recent studies have suggested that miRNAs might have a role in osteoblast differentiation and bone formation. Here, we show that miR-542-3p, a well-characterized tumor suppressor whose downregulation is tightly associated with tumor progression via C-src-related oncogenic pathways, inhibits osteoblast proliferation and differentiation. miRNA array profiling in Medicarpin (a pterocarpan with proven bone-forming effects) induced mice calvarial osteoblast cells and further validation by quantitative real-time PCR revealed that miR-542-3p was downregulated during osteoblast differentiation. Over-expression of miR-542-3p inhibited osteoblast differentiation, whereas inhibition of miR-542-3p function by anti-miR-542-3p promoted expression of osteoblast-specific genes, alkaline phosphatase activity and matrix mineralization. Target prediction analysis tools and experimental validation by luciferase 3′ UTR reporter assay identified BMP-7 (bone morphogenetic protein 7) as a direct target of miR-542-3p. It was seen that over-expression of miR-542-3p leads to repression of BMP-7 and inhibition of BMP-7/PI3K- survivin signaling. This strongly suggests that miR-542-3p suppresses osteogenic differentiation and promotes osteoblast apoptosis by repressing BMP-7 and its downstream signaling. Furthermore, silencing of miR-542-3p led to increased bone formation, bone strength and improved trabecular microarchitecture in sham and ovariectomized (Ovx) mice. Although miR-542-3p is known to be a tumor repressor, we have identified second complementary function of miR-542-3p where it inhibits BMP-7-mediated osteogenesis. Our findings suggest that pharmacological inhibition of miR-542-3p by anti-miR-542-3p could represent a therapeutic strategy for enhancing bone formation in vivo.

The alternatively initiated c-Myc proteins differentially regulate transcription through a noncanonical DNA-binding site

The myc proto-oncogene family has been implicated in multiple cellular processes, including proliferation, differentiation, and apoptosis. The Myc proteins, as heterodimers with Max protein, have been shown to function as activators of transcription through an E-box DNA-binding element, CACGTG. We have now found that the c-Myc proteins regulate transcription through another, noncanonical, DNA sequence. The non-AUG-initiated form of the c-Myc protein, c-Myc 1, strongly and specifically activates transcription of the C/EBP sequences within the EFII enhancer element of the Rous sarcoma virus long terminal repeat. In contrast, comparable amounts of the AUG-initiated form, c-Myc 2, fail to significantly affect enhancer activity. However, both c-Myc proteins trans-activate the CACGTG sequence comparably. In addition, Myc/Max heterodimers, but not Max homodimers, bind to the EFII enhancer sequence in vitro. Finally, c-Myc 1 overexpression, but not c-Myc 2 overexpression, significantly inhibits cell growth. These results reveal new transcriptional activities for the Myc proteins and demonstrate that the different forms of the Myc protein are functionally distinct. These results also suggest an interplay between two different growth regulatory transcription factor families.

Metallic radionuclides in the development of diagnostic and therapeutic radiopharmaceuticals

Metallic radionuclides are the mainstay of both diagnostic and therapeutic radiopharmaceuticals. Therapeutic nuclear medicine is less advanced but has tremendous potential if the radionuclide is accurately targeted. Great interest exists in the field of inorganic chemistry for developing target specific radiopharmaceuticals based on radiometals for non-invasive disease detection and cancer radiotherapy. This perspective will focus on the nuclear properties of a few important radiometals and their recent applications to developing radiopharmaceuticals for imaging and therapy. Other topics for discussion will include imaging techniques, radiotherapy, analytical techniques, and radiation safety. The ultimate goal of this perspective is to introduce inorganic chemists to the field of nuclear medicine and radiopharmaceutical development, where many applications of fundamental inorganic chemistry can be found.

Identification of PKD2L, a human PKD2-related gene: tissue-specific expression and mapping to chromosome 10q25

Mutations in PKD2 cause autosomal dominant kidney disease (ADPKD). Polycystin-2, the PKD2 gene product, is an integral membrane glycoprotein of unknown function. We have identified PKD2L, another member of the PKD2 gene family. PKD2L is expressed in adult heart and skeletal muscle, brain, spleen, testis, and retina, and alternative transcripts of 2.4, 2.7, and 3.0 kb are seen. PKD2L shows 56% identity and 76% similarity with polycystin-2 over a 581-amino-acid span; however, the COOH-terminal 65 residues of PKD2L are unrelated to PKD2. PKD2L is localized to chromosome 10q25 and is excluded as a candidate gene for autosomal recessive polycystic kidney disease, autosomal dominant polycystic liver disease, and the third form of ADPKD. Given the high degree of homology between PKD2L and PKD2, it is likely that the respective functions of these proteins are also closely related.

Imaging in extrapulmonary tuberculosis

Tuberculosis (TB) remains a major global public health problem, with 1.5 million deaths annually worldwide. One in five cases of TB present as extrapulmonary TB (EPTB), posing major diagnostic and management challenges. Mycobacterium tuberculosis adapts to a quiescent physiological state and is notable for its complex interaction with the host, producing poorly understood disease states ranging from latent infection to active clinical disease. New tools in the diagnostic armamentarium are urgently required for the rapid diagnosis of TB and monitoring of TB treatments, and to gain new insights into pathogenesis. The typical and atypical imaging features of EPTB are reviewed herein, and the roles of several imaging modalities for the diagnosis and management of EPTB are discussed.

Enhanced PHB production and scale up studies using cheese whey in fed batch culture of Methylobacterium sp. ZP24

Methylobacterium sp. ZP24 produced polyhydroxybutyrate (PHB) from disaccharides like lactose and sucrose. As Methylobacterium sp. ZP24 showed growth associated PHB production, an intermittent feeding strategy having lactose and ammonium sulfate at varying concentration was used towards reaching higher yield of the polymer. About 1.5-fold increase in PHB production was obtained by this intermittent feeding strategy. Further increase in PHB production by 0.8-fold could be achieved by limiting the dissolved oxygen (DO) levels in the fermenter. The decreased DO is thought to increase flux of acetyl CO-A towards PHB accumulation over TCA cycle. Cheese whey, a dairy waste product and being a rich source of utilizable sugar and other nutrients, when used in the bioreactor as a main substrate replacing the lactose, led to further increase in the PHB production by 2.5-fold. A total of 4.58-fold increase in the PHB production was obtained using limiting DO conditions with processed cheese whey supplemented with ammonium sulfate in fed batch culture of Methylobacterium sp. ZP24. The present investigation therefore reflects on the possibility of developing a cheap biological route for production of green thermoplastics.

Parathyroid hormone-related peptide in normal human fetal development

Parathyroid hormone-related peptide (PTHrP) has been detected in fetal serum and amniotic fluid. Using a combination of immunocytochemistry and molecular biology we have detected the peptide and its mRNA in a variety of fetal tissues throughout gestation. Tissue-specific mRNA isoforms were observed, the pattern of hybridization of which changed throughout gestation. In addition, the intensity and pattern of immunocytochemical localization of the peptide was found to vary over the time-period studied (8-30 weeks). PTHrP is expressed by a variety of tumours associated with the syndrome of humoral hypercalcaemia of malignancy and probably accounts for the hypercalcaemia by virtue of its limited amino acid homology with parathyroid hormone. These data demonstrate for the first time that PTHrP, a tumour-related peptide, is expressed during normal human fetal development, and suggest the possibility that it may function to regulate fetal calcium balance and growth in utero.

Antihyperglycemic activity of 2-methyl-3,4,5-triaryl-1H-pyrroles in SLM and STZ models

Various 3,4,5-triarylpyrroles were synthesized and evaluated for their in vivo antihyperglycemic activity in sucrose-loaded (SLM) and/or streptozotocin-induced (STZ) diabetic rat models. Three of the test compounds, 2-methyl-4,5-diphenyl-3-substituted-phenyl-1H-pyrroles (3c, d and h) showed significant inhibition on postprandial hyperglycemia in normal rats post sucrose loaded. These compounds also showed lowering of plasma glucose level in STZ-induced diabetic rat model.

Abrogation of cisplatin-induced programmed cell death in human breast cancer cells by epidermal growth factor antisense RNA

BACKGROUND

Epidermal growth factor receptor (EGF-R) perturbation by receptor ligand(s), e.g., epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha), or receptor-specific antibodies accentuates cisplatin-induced toxicity in tumor cells. This sensitization occurs only in tumor cells with high expression of EGF-R but not in those with low expression of EGF-R.

PURPOSE

Therefore, we have studied the role of EGF-R expression on cisplatin-mediated cytotoxicity.

METHODS

MDA-468 human breast cancer cells were stably transfected with a p-chloramphenicol acetyl transferase (pact[p]-CAT) vector containing a 4.1-kilobase full-length antisense EGF-R complementary DNA. EGF-R content was assessed by 125I-EGF binding and EGF-R immunoblot assays. Cisplatin sensitivity was evaluated by (a) colony-forming assay in vitro, (b) xenograft growth in nude mice, (c) cell cycle distribution of propidium iodide-labeled DNA, (d) DNA fragmentation in agarose gels, and (e) terminal deoxynucleotidyl transferase (Tdt) fluorescence in situ. Cisplatin uptake was measured by atomic absorption spectroscopy, and the levels of drug-DNA intrastrand adducts were determined by a dissociation-enhanced fluoroimmunoassay that utilizes an antibody against cisplatin-modified DNA.

RESULTS

Selected clones (MDA-468/AS-EGFR) exhibited more than 90% loss of both 125I-EGF binding and receptor content determined by western blot analysis, whereas clones transfected with the vector alone (MDA-468/p-CAT) had EGF-R levels similar to those of the parent cells. By use of a colony-forming assay, the 1-hour IC50 (i.e., the concentration of drug required for 1 hour to achieve 50% cell kill) for cisplatin was 2 microM or less for parental and vector-transfected clones (n = 4), whereas it was 25 microM or more for all MDA-468/AS-EGFR clones (n = 3). MDA-468/p-CAT clones exhibited internucleosomal DNA fragmentation, enhanced Tdt-end labeling in situ, and G2 arrest 48 hours after a 1-hour incubation with 3-30 microM cisplatin. Under these conditions, apoptosis and G2 arrest were undetectable in all MDA-468/AS-EGFR clones. An MDA-468 subline selected after long-term treatment with a TGF-alpha-Pseudomonas exotoxin A fusion protein 40 lacked EGF binding and also exhibited cisplatin resistance (1-hour IC50: > 30 microM) compared with parental cells. This EGF-R-dependent difference in cisplatin response was confirmed in a nude mouse xenograft model by use of high- and low-EGF-R-expressing cell clones. Total intracellular drug accumulation after a 1-hour cisplatin exposure, as measured by atomic absorption spectroscopy, was identical in both groups of cells. Intrastrand drug-DNA adducts, however, were statistically higher in high EGF-R expressors than in low-EGF-R-expressing clones.

CONCLUSIONS

These data indicate that a critical level of EGF-R signaling, which is amplified in some common human cancers, is necessary for cisplatin-mediated apoptosis in tumor cells and suggest an inhibitory effect of this pathway on the repair of cisplatin-damaged DNA.

Medicarpin, a legume phytoalexin, stimulates osteoblast differentiation and promotes peak bone mass achievement in rats: evidence for estrogen receptor β-mediated osteogenic action of medicarpin

Dietary isoflavones including genistein and daidzein have been shown to have favorable bone conserving effects during estrogen deficiency in experimental animals and humans. We have evaluated osteogenic effect of medicarpin (Med); a phytoalexin that is structurally related to isoflavones and is found in dietary legumes. Med stimulated osteoblast differentiation and mineralization at as low as 10⁻¹⁰ M. Studies with signal transduction inhibitors demonstrated involvement of a p38 mitogen activated protein kinase-ER-bone morphogenic protein-2 pathway in mediating Med action in osteoblasts. Co-activator interaction studies demonstrated that Med acted as an estrogen receptor (ER) agonist; however, in contrast to 17β-estradiol, Med had no uterine estrogenicity and blocked proliferation of MCF-7 cells. Med increased protein levels of ERβ in osteoblasts. Selective knockdown of ERα and ERβ in osteoblasts established that osteogenic action of Med is ERβ-dependent. Female Sprague-Dawley (weaning) rats were administered Med at 1.0- and 10.0 mg.kg⁻¹ doses by gavage for 30 days along with vehicle control. Med treatment resulted in increased formation of osteoporgenitor cells in the bone marrow and osteoid formation (mineralization surface, mineral apposition/bone formation rates) compared with vehicle group. In addition, Med increased cortical thickness and bone biomechanical strength. In pharmacokinetic studies, Med exhibited oral bioavailability of 22.34% and did not produce equol. Together, our results demonstrate Med stimulates osteoblast differentiation likely via ERβ, promotes achievement of peak bone mass, and is devoid of uterine estrogenicity. In addition, given its excellent oral bioavailability, Med can be potential osteogenic agent.

Measurement of parathyroid hormone-related protein in extracts of fetal parathyroid glands and placental membranes

A radioimmunoassay based on an antiserum to human parathyroid hormone-related protein PTHrP(1-16) was used with PTHrP(1-34) standard to measure the concentration of immunoreactive PTHrP in extracts of fetal parathyroid glands from lambs and calves and also placental membranes obtained from several species, including man. Dilution curves from these sources were parallel to those obtained for PTHrP(1-34) standard. It was demonstrated that this parallelism was not the result of tracer damage caused by enzymic activity in the tissue extracts. Extracts of human placental membranes were subjected to high-pressure liquid chromatography with a linear acetonitrile gradient. Co-elution of cytochemical biological activity with 125I-labelled PTHrP(1-34) was noted. These results provide further evidence for both the fetal parathyroid glands and the placenta containing material resembling PTHrP which may be responsible for sustaining the activity of the placental calcium pump which maintains the fetus hypercalcaemic relative to its mother.

Reduced graphene oxide-loaded nanocomposite scaffolds for enhancing angiogenesis in tissue engineering applications

Tissue engineering combines cells, scaffolds and signalling molecules to synthesize tissues in vitro. However, the lack of a functioning vascular network severely limits the effective size of a tissue-engineered construct. In this work, we have assessed the potential of reduced graphene oxide (rGO), a non-protein pro-angiogenic moiety, for enhancing angiogenesis in tissue engineering applications. Polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) scaffolds loaded with different concentrations of rGO nanoparticles were synthesized via lyophilization. Characterization of these scaffolds showed that the rGO-loaded scaffolds retained the thermal and physical properties (swelling, porosity and in vitro biodegradation) of pure PVA/CMC scaffolds. In vitro cytotoxicity studies, using three different cell lines, confirmed that the scaffolds are biocompatible. The scaffolds containing 0.005 and 0.0075% rGO enhanced the proliferation of endothelial cells (EA.hy926) in vitro. In vivo studies using the chick chorioallantoic membrane model showed that the presence of rGO in the PVA/CMC scaffolds significantly enhanced angiogenesis and arteriogenesis.

Synthesis of benzofuran scaffold-based potential PTP-1B inhibitors

Protein tyrosine phosphatase 1B (PTP-1B) is an enzyme that plays a critical role in down-regulating insulin signaling through dephosphorylation of the insulin receptor. Studies have shown that PTP-1B knockout mice showed increased insulin sensitivity in muscle and liver as well as resistance to obesity. A series of hydroxy benzofuran methyl ketones and their naturally mimicking dimers and linear and angular furanochalcones and flavones have been evaluated as PTP-1B inhibitors. Screened compounds displayed good inhibitory activity.

Combinatorial synthesis and biological evaluation of isoxazole-based libraries as antithrombotic agents

The 3-substituted phenyl-5-isoxazolecarboxaldehydes have been identified as activated aldehydes for the generation of isoxazole-based combinatorial libraries on solid phase through automation. Three highly functionalized isoxazole-based libraries comprising of 32, 96 and 45 compounds each have been synthesized in parallel format using Baylis Hillman reaction, Michael addition, reductive amination and alkylation reactions. With an objective of lead generation all the three libraries were evaluated for their antithrombin activity in vivo.

Design and development of novel p-aminobenzoic acid derivatives as potential cholinesterase inhibitors for the treatment of Alzheimer's disease

Based on the quantitative structure-activity relationship (QSAR), some novel p-aminobenzoic acid derivatives as promising cholinesterase enzyme inhibitors were designed, synthesized, characterized and evaluated to enhance learning and memory. The in vitro enzyme kinetic study of the synthesized compounds revealed the type of inhibition on the respective acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. The in vivo studies of the synthesized compounds exhibited significant reversal of cognitive deficits in the animal models of amnesia as compared to standard drug donepezil. Further, the ex vivo studies in the specific brain regions like the hippocampus, hypothalamus, and prefrontal cortex regions also exhibited AChE inhibition comparable to standard donepezil. The in silico molecular docking and dynamics simulations studies of the most potent compound 22 revealed the consensual interactions at the active site pocket of the AChE.

Highly Efficient Non-Palladium-Catalyzed Controlled Synthesis and X-ray Analysis of Functionalized 1,2-Diaryl-, 1,2,3-Triaryl-, and 1,2,3,4-Tetraarylbenzenes

A general, two-step, highly efficient synthesis of 1,2-diaryl-, 1,2,3-triaryl-, and 1,2,3,4-tetraarylbenzenes from simple stitching of alpha-oxo-ketene-S,S-acetals and active methylene compounds via a lactone intermediate is described. This procedure offers easy access to highly functionalized arylated benzenes that contain sterically demanding groups in good to excellent yields. The novelty of the procedure lies in the construction of aromatic compounds with the desired conformational flexibility along the molecular axis in a transition-metal-free environment through easily accessible precursors. Crystal analysis of these arylated benzene scaffolds showed that the peripheral aryl rings are arranged in a propeller-like fashion with respect to the central benzene ring. Examination of the crystal packing in the structure of a 1,2,3,4-tetraarylbenzene revealed an N...pi interaction between molecules related by a two-fold screw axis running in the direction of the a axis. Interestingly, the repeating array of N...pi interactions around the axis of this 1,2,3,4-tetraarylbenzene forces the molecules into a helical pattern.

Acetyltrimethylsilane: A Novel Reagent for the Transformation of 2H-Pyran-2-ones to Unsymmetrical Biaryls

[reaction: see text] An expeditious synthesis of unsymmetrical biaryls functionalized with electron-withdrawing or -donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one using acetyltrimethylsilane (ATMS) as a novel reagent in good yield. The novelty of the reaction lies in the creation of an aromatic ring from 2H-pyran-2-ones via two-carbon insertion from ATMS used as a source of carbanion.

A combined experimental and theoretical approach towards mechanophenotyping of biological cells using a constricted microchannel

We report a combined experimental and theoretical technique that enables the characterization of various mechanical properties of biological cells. The cells were infused into a microfluidic device that comprises multiple parallel micro-constrictions to eliminate device clogging and facilitate characterization of cells of different sizes and types on a single device. The extension ratio λ and transit velocity U_c of the cells were measured using high-speed and high-resolution imaging which were then used in a theoretical model to predict the Young's modulus E_c = f(λ, U_c) of the cells. The predicted Young's modulus E_c values for three different cell lines (182 ± 34.74 Pa for MDA MB 231, 360 ± 75 Pa for MCF 10A and, 763 ± 93 Pa for HeLa) compare well with those reported in the literature from micropipette measurements and atomic force microscopy measurement within 10% and 15%, respectively. Also, the Young's modulus of MDA-MB-231 cells treated with 50 μM 4-hyrdroxyacetophenone (for localization of myosin II) for 30 min was found out to be 260 ± 52 Pa. The entry time t_e of cells into the micro-constrictions was predicted using the model and validated using experimentally measured data. The entry and transit behaviors of cells in the micro-constriction including cell deformation (extension ratio λ) and velocity U_c were experimentally measured and used to predict various cell properties such as the Young's modulus, cytoplasmic viscosity and induced hydrodynamic resistance of different types of cells. The proposed combined experimental and theoretical approach leads to a new paradigm for mechanophenotyping of biological cells.

Rapid measurement of hydrogen sulphide in human blood plasma using a microfluidic method

Hydrogen sulfide (H₂S) is emerging as an important gasotransmitter in both physiological and pathological states. Rapid measurement of H₂S remains a challenge. We report a microfluidic method for rapid measurement of sulphide in blood plasma using Dansyl-Azide, a fluorescence (FL) based probe. We have measured known quantities of externally added (exogenous) H₂S to both buffer and human blood plasma. Surprisingly, a decrease in FL intensity with increase in exogenous sulphide concentration in plasma was observed which is attributed to the interaction between the proteins and sulphide present in plasma underpinning our observation. The effects of mixing and incubation time, pH, and dilution of plasma on the FL intensity is studied which revealed that the FL assay required a mixing time of 2 min, incubation time of 5 min, a pH of 7.1 and performing the test within 10 min of sampling; these together constitute the optimal parameters at room temperature. A linear correlation (with R² ≥ 0.95) and an excellent match was obtained when a comparison was done between the proposed microfluidic and conventional spectrofluorometric methods for known concentrations of H₂S (range 0–100 µM). We have measured the baseline level of endogenous H₂S in healthy volunteers which was found to lie in the range of 70 μM – 125 μM. The proposed microfluidic device with DNS-Az probe enables rapid and accurate estimation of a key gasotransmitter H₂S in plasma in conditions closely mimicking real time clinical setting. The availability of this device as at the point of care, will help in understanding the role of H₂S in health and disease.

Isoformononetin, a methoxydaidzein present in medicinal plants, reverses bone loss in osteopenic rats and exerts bone anabolic action by preventing osteoblast apoptosis

PURPOSE

Daidzein (Daid) has been implicated in bone health for its estrogen-'like' effects but low bioavailability, unfavorable metabolism and uterine estrogenicity impede its clinical potential. This study was aimed at assessing isoformononetin (Isoformo), a naturally occurring methoxydaidzein, for bone anabolic effect by overcoming the pitfalls associated with Daid.

METHODS

Sprague-Dawley ovariectomized (OVx) rats with established osteopenia were administered Isoformo, 17β-oestradiol (E2) or human parathyroid hormone. Efficacy was evaluated by bone microarchitecture using microcomputed tomography and determination of new bone formation by fluorescent labeling of bone. Osteoblast apoptosis was measured by co-labeling of bone sections with Runx-2 and TUNEL. Biochemical markers of bone metabolism were measured by ELISA. Plasma and bone marrow levels of Isoformo and Daid were determined by LC-MS-MS. Rat bone marrow stromal cells were harvested to study osteoblastic differentiation by Isoformo and Daid. New born rat pups were injected with Isoformo and Daid to study the effect of the compounds on the expression of osteogenic genes in the calvaria by real time PCR.

RESULTS

In osteopenic rats, Isoformo treatment restored trabecular microarchitecture, increased new bone formation, increased the serum osteogenic marker (procollagen N-terminal propeptide), decreased resorptive marker (urinary C-terminal teleopeptide of type I collagen) and diminished osteoblast apoptosis in bone. At the most effective osteogenic dose of Isoformo, plasma and bone marrow levels were comprised of ~90% Isoformo and the rest, Daid. Isoformo at the concentration reaching the bone marrow achieved out of its most effective oral dosing induced stromal cell mineralization and osteogenic gene expression in the calvaria of neonatal rats. Isoformo exhibited uterine safety.

CONCLUSIONS

Our study demonstrates that Isoformo reverses established osteopenia in adult OVx rats likely via its pro-survival effect on osteoblasts. Given its bone anabolic and anti-catabolic effects accompanied with safety at uterine level we propose its potential in the management of postmenopausal osteoporosis.