Rgp1 contributes to craniofacial cartilage development and Rab8a-mediated collagen II secretion.

Rgp1 was previously identified as a component of a guanine nucleotide exchange factor (GEF) complex to activate Rab6a-mediated trafficking events in and around the Golgi. While the role of Rgp1 in protein trafficking has been examined in vitro and in yeast, the role of Rgp1 during vertebrate embryogenesis and protein trafficking in vivo is unknown. Using genetic, CRISPR-induced zebrafish mutants for Rgp1 loss-of-function, we found that Rgp1 is required for craniofacial cartilage development. Within live rgp1-/- craniofacial chondrocytes, we observed altered movements of Rab6a+ vesicular compartments, consistent with a conserved mechanism described in vitro. Using transmission electron microscopy (TEM) and immunofluorescence analyses, we show that Rgp1 plays a role in the secretion of collagen II, the most abundant protein in cartilage. Our overexpression experiments revealed that Rab8a is a part of the post-Golgi collagen II trafficking pathway. Following loss of Rgp1, chondrocytes activate an Arf4b-mediated stress response and subsequently respond with nuclear DNA fragmentation and cell death. We propose that an Rgp1-regulated Rab6a-Rab8a pathway directs secretion of ECM cargoes such as collagen II, a pathway that may also be utilized in other tissues where coordinated trafficking and secretion of collagens and other large cargoes is required for normal development and tissue function.

Caviunin glycoside (CAFG) from Dalbergia sissoo attenuates osteoarthritis by modulating chondrogenic and matrix regulating proteins.

ETHNOPHARMACOLOGICAL RELEVANCE: Dalbergia sissoo DC. (Indian rosewood or Sheesham) is a traditional medicinal plant, reported since time immemorial for its analgesic, anti-nociceptive, anti-inflammatory, and immuno-modulatory properties. D. sissoo DC (DS). is being used traditionally to cure joint inflammation and joint pain. AIM: To study the potential of DS leaves and its derived novel compound CAFG to treat the clinical symptoms of osteoarthritis (OA) and its underlying mechanism. METHODS: The chemical profile of DS extract (DSE) with isoflavonoids and isoflvaonoid glycosides from the DS was established by UHPLC-PDA and UHPLC-MS/MS. Monosodium iodoacetate (MIA) was injected into the knee joint to develop the OA model in rats. DSE was given orally for 28 days daily at 250 and 500 mg.kg-1day-1. For in-vitro experiments, chondrocytes isolated from joint articular cartilage were negatively induced with interleukin-1ß (IL-1ß) and CAFG was given to the cells as a co-treatment. RESULTS: Chondrocytes undergo apoptosis following inflammation and proteoglycan synthesis affected in MIA injected knees. DSE administration prevented these effects as assessed by H&E and Toluidine blue staining. Micro-CT analysis showed that subchondral bone loss was restored. DSE decreased elevated serum levels of cartilage-bone degradation (CTX-I, CTX-II, and COMP), inflammation markers IL-1ß, and matrix-degrading MMP-3 and 13. The effects of IL-1ß on gene expression of chondrocytes were reversed by CAFG treatment at 1 µM. CONCLUSION: Data showed that DSE protected joint cartilage and deterioration in subchondral bone in vivo while in in-vitro, its active ingredient CAFG prevented interleukin-1ß induced effects and inhibited OA. This finding suggest that DSE and CAFG could be used as a possible therapeutic to treat osteoarthritis.

Glucocorticoid aggravates bone micro-architecture deterioration and skeletal muscle atrophy in mice fed on high-fat diet.

High fat diet (HFD) induced obesity has deleterious effect on bone micro-architecture and is associated with low-grade chronic inflammation. Exogenous glucocorticoids (GC) are used to treat inflammatory conditions but with concomitant adverse effect on musculoskeletal system. This study aims to highlight the effect of exogenous GCs on musculoskeletal system in mice fed on HFD. Adult BALB/c mice were fed either normal chow or high fat diet and were exogenously administered with GC for 10 weeks. At the end of the study, animals were autopsied and bone, muscle, serum samples were collected for micro-CT, gene expression and histological study. HFD induced obesity resulted in deterioration in bone micro-architecture predominant in trabecular region of long bones and was significantly amplified with GC administration. Approximately, 37% and 25% loss in femoral and tibial bone volume was observed in obese animals with exogenous GC. Further, deteriorating bone pathology was apparent from reduced bone mineral density (BMD) and bone strength parameter which was correlated to alteration in osteoblast and adipocytes pool of cells in bone marrow. Transcriptional analysis of osteoblast marker genes, bone morphogenetic protein 2 (BMP-2), osteocalcin (OCN) exhibited decreased formation. Moreover, similar degeneration was observed in skeletal muscle physiology with stimulation in muscle atrophy genes atrogin-1, muscle ring finger motif-1 (MuRF-1) and inflammatory markers accompanied with intra-myocellular lipid accumulation. Thus, our results showed that detrimental effect of GC on bone and skeletal muscle is aggravated with HFD, attributed to alteration in bone marrow cell population and skeletal muscle atrophy.

FGF-2 targets sclerostin in bone and myostatin in skeletal muscle to mitigate the deleterious effects of glucocorticoid on musculoskeletal degradation.

AIM: Myokines are associated with regulation of bone and muscle mass. However, limited information is available regarding the impact of myokines on glucocorticoid (GC) mediated adverse effects on the musculoskeletal system. This study investigates the role of myokine fibroblast growth factor-2 (FGF-2) in regulating GC-induced deleterious effects on bone and skeletal muscle. METHODS: Primary osteoblast cells and C2C12 myoblast cell line were treated with FGF-2 and then exposed to dexamethasone (GC). FGF-2 mediated attenuation of the inhibitory effect of GC on osteoblast and myoblast differentiation and muscle atrophy was assessed through quantitative PCR and western blot analysis. Further, FGF-2 was administered subcutaneously to dexamethasone treated mice to collect bone and skeletal muscle tissue for in vivo analysis of bone microarchitecture, mechanical strength, histomorphometry and for histological alterations in treated tissue samples. KEY FINDINGS: FGF-2 abrogated the dexamethasone induced inhibitory effect on osteoblast differentiation by modulating BMP-2 pathway and inhibiting Wnt antagonist sclerostin. Further, dexamethasone induced atrophy in C2C12 cells was mitigated by FGF-2 as evident from down regulation of atrogenes expression. FGF-2 prevented GC-induced impairment of mineral density, biomechanical strength, trabecular bone volume, cortical thickness and bone formation rate in mice. Additionally, skeletal muscle tissue from GC treated mice displayed weak myostatin immunostaining and reduced expression of atrogenes following FGF-2 treatment. SIGNIFICANCE: FGF-2 mitigated GC induced effects through inhibition of sclerostin and myostatin expression in bone and muscle respectively. Taken together, this study exhibited the role of exogenous FGF-2 in sustaining osteoblastogenesis and inhibiting muscle atrophy in presence of glucocorticoid.

Benzofuran-pyran hybrids: A new class of potential bone anabolic agents.

Benzofuran moiety is an important pharmacophore showing positive effects on bone health. In the present study, sixteen benzofuran-pyran hybrids were synthesized and were evaluated for their osteogenic effects on primary osteoblast cells isolated from calvaria. Compounds 22 and 24 were found potent in stimulating osteoblast differentiation as assessed by the alkaline phosphatase activity. These compounds were also found to be nontoxic to osteoblast cells as compared to the control cells in MTT assay. Further, Alizarin Red-S staining for visualization of calcium nodules demonstrated compounds 22 and 34 as active in enhancing mineralization in osteoblast cells. Additionally, transcriptional analysis of these compounds on osteoblast cells revealed that compound 22 up-regulated the expression of osteogenic genes RUNX2, BMP-2, COL-1, thus substantiating that compound 22 having two geminal methyl groups in its R3 position is a potent osteogenic agent. Additionally, compound 22 enhanced the ability of bone marrow stromal cells to differentiate towards osteoblast lineage and therefore can be further studied in vivo in bone loss model.

Dietary flavonoid kaempferol inhibits glucocorticoid-induced bone loss by promoting osteoblast survival.

OBJECTIVE: Kaempferol, a dietary flavonoid found in fruits and vegetables, has been reported to reverse osteopenic condition in ovariectomized rats. Because kaempferol is endowed with osteogenic activity, the aim of this study was to determine whether it has a beneficial effect on glucocorticoid (GC)-induced bone loss. METHODS: Adult female rats were divided into four groups as control (vehicle; distilled water), methylprednisolone (MP; 5 mg•kg•d, subcutaneously), MP + kaempferol (5 mg•kg•d, oral), and MP + human parathyroid 1-34 (30 µg/kg, 5 times/wk, subcutaneously) and treated for 4 wk. To study the antagonizing effect of kaempferol on GC-induced inhibition of fracture healing, drill-hole injury was performed on control and GC-treated rats. An oral dose of kaempferol was given for 14 d to observe the effect on callus formation at the site of injury. After treatment, bones were collected for further analysis. RESULTS: GC was associated with a decreased bone mineral density and impaired bone microarchitecture parameters. Consumption of kaempferol induced bone-sparing effects in GC-induced osteopenic condition. Additionally, improved callus formation at site of drill injury in femur diaphysis was observed with kaempferol consumption in animals on GC. Consistent with the in vivo data, kaempferol elicited a higher expression of osteogenic markers in vitro and antagonized the apoptotic effect of dexamethasone on calvarial osteoblasts. CONCLUSION: These results suggested that kaempferol reduced GC-induced bone loss and enhanced bone regeneration at fractured site, thus emphasizing the positive role of flavonoids on bone health.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats.

BACKGROUND: Spinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA). METHODS: OA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg- 1 day- 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker's and behavioural experiments. RESULTS: In vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test. CONCLUSION: On the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Prevention of articular cartilage degeneration in a rat model of monosodium iodoacetate induced osteoarthritis by oral treatment with Withaferin A.

Withaferin A (WFA), a highly oxygenated withanolide is used for anti-osteoporotic, fracture healing, obesity control as medicine and dietary supplement in Ayurveda and Unani medicine but its potential remains to be investigate for the osteoarthritis studies. In the present study, chondro-protective effects of WFA, under in vitro and in vivo conditions were evaluated. In-vitro pharmacological activity of WFA was tested on rat articular chondrocytes through MTT, DPPH, different staining, FACS and translation studies. In-vivo studies of WFA were evaluated through monosodium iodoacetate (MIA) induced osteoarthritis studies. DPPH assay, alcian blue and toluidine blue staining indicated the chondrogenic potential of WFA. Similarly, WFA enhance chondrogenesis through up-regulation of SOX9 protein. In addition, WFA reduced the ROS generation, mitochondrial depolarization and apoptosis induced by inflammatory cytokines IL-1ß and TNF-α. Furthermore, WFA treatment in MIA treated rats alleviated cartilage erosion and improvement in sub-chondral bone micro-architecture by decrease in Tissue volume (∼32%), and trabecular bone pattern factor (∼28%). Taken together, our study provides convincing evidence for the candidature of WFA (10 mg kg-1 day-1) as a potential agent for the treatment of cartilage degenerative diseases like osteoarthritis.

Benzofuran-dihydropyridine hybrids: A new class of potential bone anabolic agents.

A series of novel benzofuran-dihydropyridine hybrids were designed by molecular hybridization approach and evaluated for bone anabolic activities. Among the screened library, ethyl 4-(7-(sec-butyl)-2-(4-methylbenzoyl)benzofuran-5-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate (compound 21) significantly enhanced the ALP production and mineralized nodule formation, which are primary requisites in the process of in vitro osteogenesis. Oral administration of compound 21 at 10 mg.kg-1 day-1 for two weeks led to restoration of trabecular bone microarchitecture in drill hole fracture model by significantly increasing BV/TV and Tb.N. Furthermore, histological and molecular studies showed compound 21 triggering the new bone regeneration in a drill hole defect site by increasing BMP expression. Furthermore, molecular modeling studies were performed to gain insight into the binding approach, which revealed that both benzofuran and dihydropyridine moieties are essential to show similar binding interactions to fit into the active site of BMP2 receptor, an important target of the osteogenic agents. Our results suggest that compound 21 stimulates BMP2 synthesis in osteoblast cells that promotes new bone formation (∼40%) at the fracture site which helps in shorten the healing period.

Detrimental effects of atherogenic and high fat diet on bone and aortic calcification rescued by an isoflavonoid Caviunin ß-d-glucopyranoside.

OBJECTIVE: Atherogenic diet (AD) and high fat diet (HFD) cause deleterious effect on bone micro-architecture and this phenomenon prompts aortic calcification. This study aims to show the effects of Caviunin ß-d-glucopyranoside (CAFG), against bone loss and its associated aortic calcification in presence of AD and HFD challenged diets. METHODS: Five groups of C57BL/6 male mice with 8 animals in each group, comprising of chow, AD, HFD, AD+CAFG and HFD+CAFG were fed with respective diets for 16 weeks. At the end of the treatment period, preventive effects of CAFG on bone tissue were analyzed by assessing the osteogenic potential of bone marrow cells, bone micro-architecture, ability of new bone formation and histomorphometry studies. Aortic calcification was assessed by transcription and translation analysis of osteogenic key markers in aortic tissue and assessment of aortic endothelial function. Plasma lipid profiling was done to assess the effects of diets as its role in both bone loss and aortic calcification. RESULTS: Bone marrow stromal cell (BMSC's) dynamics showed that AD and HFD decreased osteoblast number that led to bone loss, deterioration in bone micro-architecture with up-regulated bone resorptive genes that lead to increase in aortic calcification. CAFG treatment rescued the bone health by modulating BMSC's towards osteogenic lineage. It increased the osteogenic gene expression with simultaneous decrease in osteoclastic genes thus stabilized the receptor activator of nuclear factor-kappa-B ligand/osteoprotegerin ratio that eventually reduced the amount of calcification in aorta. Biochemical studies showed that CAFG reduced the TC, TG and LDL-C content with no marked changes in HDL-C. Moreover, CAFG decreased the osteogenic key markers in the aortic tissue and enhanced endothelial function. CONCLUSION: Overall, this study indicates that CAFG protected against physiologically challenged diet induced bone loss with associated vascular calcification in mice. Moreover, data revealed that atherogenic diet is more detrimental as compared to the excess fatty acid diet to the bone and aorta.

Formononetin, an isoflavone, activates AMP-activated protein kinase/ß-catenin signalling to inhibit adipogenesis and rescues C57BL/6 mice from high-fat diet-induced obesity and bone loss.

Balance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of ß-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT's rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/ß-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.

Evaluation of anti-osteoporotic activity of butanolic fraction from Passiflora foetida in ovariectomy-induced bone loss in mice.

OBJECTIVE: In this study, we have evaluated the skeletal effects of butanolic fraction (BF) from Passiflora foetida in an estrogen deficient mice bone loss model. STUDY DESIGN: Skeletal effect of BF was studied in ovariectomized (OVx) female Balb/c mice. BF (50 and 100mg/kg/day dose orally) was given for 8 weeks. Micro-architecture of long bones, biomechanical strength, formations of mineralized nodule by bone marrow osteoprogenitor cells, osteoid formation and bone turnover markers were studied. One way ANOVA was used to test the significance of effects of Passiflora foetida. RESULTS: OVx mice treated with BF represented with better micro-architectural parameters at various anatomical positions, better bone biomechanical strength and more osteoprogenitor cells in the bone marrow compared with OVx group. BF did not exhibit uterine estrogenicity. CONCLUSION: Oral administration of BF at both the doses (50 and 100mg/kg/day) derived from Passiflora Foetida, was found to afford anti-osteoporotic effect under estrogen deficiency by likely stimulation of osteoblast function and inhibition of osteoclast function.

Dried and free flowing granules of Spinacia oleracea accelerate bone regeneration and alleviate postmenopausal osteoporosis.

OBJECTIVE: The aim of this study was to demonstrate the efficacy of extract derived from Spinacia oleracea extract (SOE) in reversing bone loss induced by ovariectomy and bone healing properties in a drill-hole fracture model in rats. METHODS: SOE was administered orally for 12 weeks in adult ovariectomized Sprague Dawley rats after inducing osteopenic condition. Bone micro-architecture, expressions of osteogenic and resorptive gene markers, biomechanical strength, new bone formation, and bone turnover markers were studied. Uterine histomorphometry was used to assess estrogenicity. Bone regeneration potential of SOE was assessed in a drill-hole fracture model. Fracture healing was assessed by calcein intensity and micro-CT analysis of callus at fracture region. RESULTS: SOE prevented ovariectomy-induced bone loss as evident from 122% increase in bone volume/tissue volume (BV/TV) and 29% decline in Tb.Sp in femoral trabecular micro-architecture. This was corroborated by the more than twofold stimulation in the expression of osteogenic genes runt-related transcription factor 2, osterix, osteocalcin, bone morphogenetic protein 2, collagen-1. Furthermore in the fracture healing model, we observed a 25% increase in BV/TV and enhancement in calcein intensity at the fractured site. The extract when converted into dried deliverable Spinaceae oleracea granule (SOG) form accelerated bone regeneration at fracture site, which was more efficient as evident by a 39% increase in BV/TV. Transforming SOE into dried granules facilitated prolonged systemic availability, thus providing enhanced activity for a period of 14 days. CONCLUSIONS: SOE treatment effectively prevents ovariectomy-induced bone loss and stimulated fracture healing in adult rats. The dried granular form of the extract of Spinaceae oleracea was effective in fracture healing at the same dose.

Fast and long acting neoflavonoids dalbergin isolated from Dalbergia sissoo heartwood is osteoprotective in ovariectomized model of osteoporosis: Osteoprotective effect of Dalbergin.

OBJECTIVE: This study aims to evaluate the skeletal effects of dalbergin (DBN), isolated from Dalbergia sissoo heartwood, in ovariectomized (OVx) BALB/c mice, a postmenopausal osteoporosis model of bone loss. METHODS: Adult BALB/c mice were used and randomly assigned in to six groups with 6 animals (n=6) in each group: sham (surgery operated without ovariectomy) with vehicle, ovariectomy with vehicle, ovariectomy (OVx) with estradiol (E2 5.0µgkg-1day-1), or ovariectomy with dalbergin at three different doses of DBN (1.0, 5.0 and10mgkg-1day-1). Daily oral administration of the vehicle, estradiol, or DBN was started 8 weeks post-surgery and continued for 8 weeks. At the end of experiment, mice were sacrificed and assessed for trabecular bone structure of tibia, lumbar vertebra (L5) and alterations in biochemical and uterine parameters, pharmacokinetic profile and gene expression were monitored for each group. RESULTS: Treatment with DBN prevented trabecular bone loss in cancellous bone in the tibial metaphysis and lumbar vertebra region of the ovariectomized mice. Micro-CT data showed that mice treated with DBN at 1.0mgkg-1day-1 exhibited improved bone micro-architecture that was sustained with decreased expression of bone resorption markers like TRAP and RANK and caused an increase in osteogenic markers like RUNX2, BMP2 and OPG/RANKL ratio compared with OVx+vehicle treated mice. Moreover, DBN treatment induced no uterine estrogenicity and significantly lowered the osteocalcin amount in serum when compared with OVx+V group. DBN reached its maximum concentration (Cmax) 238.49±21.37ngml-1 in serum as early as 1h of administration. Overall, DBN (1.0mgkg-1day-1) treatment exhibited similar bone conserving effect against bone-loss as estradiol treatment. CONCLUSION: Daily oral administration of DBN for 8 weeks showed significant anabolic effects on bone micro-architectural parameters along with down regulation of bone resorptive markers without compromising safety at uterine level. Therefore, our study provides basis for DBN as a therapeutic candidate against postmenopausal osteoporosis.

An isoflavone cladrin prevents high-fat diet-induced bone loss and inhibits the expression of adipogenic gene regulators in 3T3-L1 adipocyte.

OBJECTIVE: This study evaluates the effect of isoflavone cladrin on high-fat diet (HFD)-induced bone loss and adipogenesis. METHODS: Thirty-two 4-week-old male C57BL/6J mice were divided into four groups: a standard diet group, a HFD group and HFD group with cladrin (5 and 10 mg/kg per day orally) for 12 weeks. The effect of cladrin on bone micro-architecture, bone marrow cell lineages and hyperlipidaemia were assessed. For assessing anti-adipogenic activity of cladrin, 3T3-L1 cells were used. KEY FINDINGS: Cladrin attenuated HFD-induced hyperlipidaemia and bone loss by preserving bone micro-architecture and strength. Effect of cladrin was found at the level of bone marrow progenitor cells. Gene expression profile of cladrin-treated mice bone showed upregulation of osteoblast and downregulation of adipogenic transcription factors and increased OPG/RANKL ratio. Cladrin inhibited cellular lipid accumulation through downregulation of transcription factors such as PPAR-γ and C/EBP-α and modulated the expression of major adipokines involved behind obesity stimulation without eliciting cell cytotoxicity in 3T3-L1 adipocytes. CONCLUSION: We conclude that cladrin may improve obesity-induced bone loss and hyperlipidaemia in mice fed HFD and adipogenesis in 3T3-L1 cells by modifying adipokines and could offer clinical benefits as a supplement to treat obesity-induced disorders.

Kaempferol targets Krt-14 and induces cytoskeletal mineralization in osteoblasts: A mechanistic approach.

Kaempferol (KEM) has been observed to stimulate Krt-14 protein which subsequently contributes to matrix maturation and mineralization in rat primary osteoblast cells. Incorporation of Krt-14 siRNA results in reduced mRNA and protein expression after 48h post transfection and remained low for 9days. At day 9 Krt-14 siRNA significantly reduced mineralization without concomitant change in the cell number. ColI and OCN gene expression was reduced in Krt-14 siRNA-treated osteoblast cells. Soluble osteocalcin and collagen levels were markedly decreased in conditioned medium as well as in acid-salt soluble cell-ECM layer treated with Krt-14 siRNA compared to control siRNA treated cells corroborated at the ultrastructral level by AFM. Further, knockdown of Krt-14 and inhibitors against AMPK and mTOR, repressed the activation of mTOR and mineralization attenuated by KEM confirmed the role of Krt-14 in mineralization. These findings strongly suggest that Krt-14 regulates osteoblast mineralization by organizing osteoblast derived ECM.

Genetically engineered flavonol enriched tomato fruit modulates chondrogenesis to increase bone length in growing animals.

Externally visible body and longitudinal bone growth is a result of proliferation of chondrocytes. In growth disorder, there is delay in the age associated increase in height. The present study evaluates the effect of extract from transgenic tomato fruit expressing AtMYB12 transcription factor on bone health including longitudinal growth. Constitutive expression of AtMYB12 in tomato led to a significantly enhanced biosynthesis of flavonoids in general and the flavonol biosynthesis in particular. Pre-pubertal ovary intact BALB/c mice received daily oral administration of vehicle and ethanolic extract of wild type (WT-TOM) and transgenic AtMYB12-tomato (MYB12-TOM) fruits for six weeks. Animal fed with MYB12-TOM showed no inflammation in hepatic tissues and normal sinusoidal Kupffer cell morphology. MYB12-TOM extract significantly increased tibial and femoral growth and subsequently improved the bone length as compared to vehicle and WT-TOM. Histomorphometry exhibited significantly wider distal femoral and proximal tibial growth plate, increased number and size of hypertrophic chondrocytes in MYB12-TOM which corroborated with micro-CT and expression of BMP-2 and COL-10, marker genes for hypertrophic cells. We conclude that metabolic reprogramming of tomato by AtMYB12 has the potential to improve longitudinal bone growth thus helping in achievement of greater peak bone mass during adolescence.

AtMYB12 expression in tomato leads to large scale differential modulation in transcriptome and flavonoid content in leaf and fruit tissues.

Plants synthesize secondary metabolites, including flavonoids, which play important role during various stresses for their survival. These metabolites are also considered as health-protective components in functional foods. Flavonols, one of the important groups of flavonoids, apart from performing several roles in plants have been recognized as potent phytoceuticals for human health. Tomato fruits are deficient in this group of flavonoids and have been an important target for enhancing the accumulation of flavonols through genetic manipulations. In the present study, AtMYB12 transcription factor of the Arabidopsis has been expressed under constitutive promoter in tomato. Transgenic tomato lines exhibited enhanced accumulation of flavonols and chlorogenic acid (CGA) in leaf and fruit accompanied with elevated expression of phenylpropanoid pathway genes involved in flavonol biosynthesis. In addition, global gene expression analysis in leaf and fruit suggested that AtMYB12 modulates number of molecular processes including aromatic amino acid biosynthesis, phytohormone signaling and stress responses. Besides this, a differential modulation of the genes in fruits and leaves is reported in this study. Taken together, results demonstrate that modulation of primary carbon metabolism and other pathways by AtMYB12 in tomato may lead to sufficient substrate supply for enhanced content of phenolics in general and flavonols in particular.

Neoflavonoid dalbergiphenol from heartwood of Dalbergia sissoo acts as bone savior in an estrogen withdrawal model for osteoporosis.

OBJECTIVE: Dalbergiphenol (DGP) is a neoflavonoid isolated from heartwood of Dalbergia sissoo. Effects of DGP on skeletal health remain to be elucidated. The objective of the present study was to investigate the biological effects of DGP on bone loss in ovariectomized mice. METHODS: Adult BALB/c mice were ovariectomized and administered DGP (1 and 5  mg/kg/d) or 17ß-estradiol (E2) orally for 6 weeks. The sham group and the ovariectomy (OVX) + vehicle group served as controls. Eight female BALB/c mice were taken for each group. Uterine estrogenicity, bone microarchitecture, biomechanical strength, new bone formation (based on bone formation rate and mineral apposition rate), and skeletal expression of osteogenic and resorptive gene markers were studied. RESULTS: OVX resulted in a marked increase in body weight and a decrease in femoral and vertebral trabecular bone volume that were prevented by DGP or E2 treatment. DGP treatment increased bone biomechanical strength and new bone formation rate in ovariectomized mice, comparable with E2 treatment. However, increase in uterine weight and estrogenicity were observed in E2-treated ovariectomized mice, but not in response to DGP treatment. Treatment with DGP increased messenger RNA expression of runt-related transcription factor 2, osterix, and collagen type I, and decreased messenger RNA expression of tartrate-resistant acid phosphatase and the osteoprotegerin-to-receptor activator of nuclear factor-κB ligand ratio in the femur of ovariectomized mice. CONCLUSIONS: Overall findings suggest that DGP treatment can effectively prevent OVX-induced increase in bone loss and decrease in bone strength possibly by increasing osteoblastic activities and by decreasing osteoclastic activities.

Neoflavonoids as potential osteogenic agents from Dalbergia sissoo heartwood.

The present study was undertaken to investigate and rationalize the in vitro antiosteoporotic activity of neoflavonoids, isolated from Dalbergia sissoo heartwood. Neoflavonoids were isolated using extensive column chromatography and identified as dalsissooal (1) a new compound and cearoin (2), dalbergin (3), 4-methoxy dalbergion (4), dalbergiphenol (5), dalbergichromene (6), methyl dalbergin (7) and latinone (8) as known compounds by comparison their spectroscopic data with those reported in the literature. Among the screened compounds, compounds 1, 3, 5-8 significantly increased proliferation as assessed by alkaline phosphatase activity and mineralization in calvarial osteoblast cells.