Control of chondrocyte gene expression by actin dynamics: a novel role of cholesterol/Ror-alpha signalling in endochondral bone growth.
"The signalling pathways that regulate chondrocyte differentiation [include] the actin cytoskeleton and Rho GTPases. Manipulation of actin dynamics in tibia organ cultures isolated from E15.5 mice results in pronounced enhancement of endochondral bone growth and specific changes in growth plate architecture. Global changes in gene expression were examined of primary chondrocytes isolated from embryonic tibia, treated with the compounds cytochalasin D, jasplakinolide (actin modifiers) and the ROCK inhibitor Y27632. Cytochalasin D elicited the most pronounced response and induced many features of hypertrophic chondrocyte differentiation. Bioinformatics analyses of microarray data and expression validation by real-time PCR and immunohistochemistry resulted in the identification of the nuclear receptor retinoid related orphan receptor-alpha (Ror-alpha) as a novel putative regulator of chondrocyte hypertrophy. Expression of Ror-alpha target genes, (Lpl, fatty acid binding protein 4 [Fabp4], Cd36 and kruppel-like factor 5 [Klf15]) were induced during chondrocyte hypertrophy and by cytochalasin D and are cholesterol dependent. Stimulation of Ror-alpha by cholesterol results in increased bone growth and enlarged, rounded cells, a phenotype similar to chondrocyte hypertrophy and to the changes induced by cytochalasin D, while inhibition of cholesterol synthesis by lovastatin inhibits cytochalasin D induced bone growth. Additionally, we show that in a mouse model of cartilage specific (Col2-Cre) Rac1, inactivation results in increased Hif-1alpha (a regulator of Rora gene expression) and Ror-alpha(+) cells within hypertrophic growth plates. We provide evidence that cholesterol signalling through increased Ror-alpha expression stimulates chondrocyte hypertrophy and partially mediates responses of cartilage to actin dynamics."
Cholesterol activates Ror-alpha expression. Ror-alpha stimulates chondrocyte hypertrophy. Chondrocyte hypertrophy is one of the ways to stimulate height growth. Note that Lovastatin may be better at stimulating chondrogenic differentiation while chosterol may be more helpful in chondrocyte hypertrophy.
"RhoA/ROCK signalling inhibits both early and late chondrocyte differentiation in vitro. Actin polymerization re-establishes chondrocyte gene expression in de-differentiated chondrocytes in vitro. Manipulation of the actin cytoskeleton promotes the differentiation of mesenchymal cells to the chondrocyte lineage in vitro."
"inhibition of ROCK signalling by Y27632 results in an expanded resting zone, whereas the proliferative and hypertrophic zones sizes remain unchanged"<-The resting zone is the zone most likely to induce an increase in adult height rather than just growth rate.
"Inhibition of actin polymerization by cytochalasin D resulted in a growth plate that was too unorganized to distinguish and measure any zones. Instead, the cellular morphology of cytochalasin D treated tibiae showed features of hypertrophic and resting chondrocytes; cells were larger but were also surrounded by an abundant matrix."<-Note cytochalasin D still resulted in an increase in longitudinal growth despite a disruption in growth plate zones.
CytD upregulates ATF3 by 9.3 which LSJL also upregulates.
"Hif-1α gene expression was found to be up-regulated in response to cytochalasin D treatment"
"Analysis of growth plate organization demonstrated that cholesterol treatment resulted in similar growth plate morphology as cytochalasin D. Chondrocytes were rounder and larger than control cells; however, cholesterol treatment did not alter growth plate architecture as severely as cytochalasin D treatment because we could still distinguish columnar stacks in the proliferative zone of cholesterol treated bones"
"Fabp4, Cd36, Lpl and Klf15 mRNA levels are all responsive to cholesterol signalling and their up-regulation in the microarray are likely due to the increase in Ror-α expression and activity"
"Cholesterol itself may also be regulating chondrocyte hypertrophy directly, through activation of Ror-α and downstream target genes (e.g. genes involved in lipid metabolism)."
Yeast hydrolysate induces longitudinal bone growth and growth hormone release in rats.
"This study investigated the growth promoting effects of yeast extract (YH) fed to Sprague-Dawley male rats (3 weeks old) for 4 weeks. The negative (N)-control and positive (P)-control groups were given a daily oral administration of saline and foremilk (1 g/kg of BW), respectively, and the YH-1 and YH-2 groups were given daily administrations of YH (0.5 and 1 g/kg of BW, respectively). After 4 weeks, the YH-1, YH-2 and P-control groups showed significant differences in the body weight gain compared with the N-control group (p < 0.05). The YH-1 and YH-2 groups also had significantly different tibial bone growths (0.47 and 0.49 mm/day, respectively) and femur bone growths (0.52 and 0.53 mm/day, respectively) compared with the N-control group (0.37 mm/day of tibial growth and 0.42 mm/day of femur growth) (p < 0.05). The YH-1 and YH-2 groups had significantly different growth plate (proximal epiphysis) height increments (0.62 and 0.56 mm, respectively) compared with the N-control group (0.17 mm) (p < 0.05). Lastly, the YH-1 and YH-2 groups presented different growth hormone (GH) levels (1.77 and 2.10 ng/mL, respectively) than the N-control group (0.82 ng/mL) (p < 0.05). YH administration increased longitudinal bone growth and GH secretion in rats. Consequently, YH may offer an improved ability to treat GH deficiency-related disorders."
Yeast Extract increases some forms of cholesterol. What's interesting about the study is that the results were dose dependent. The group that ate twice as much yeast had between 0.04-0.05mm of extra growth. But remember growth rate does not always equal increased(or decreased) growth! Yeast is available for sale(Marmite Yeast Extract 125gram - Pack of 2 Jars!
) but I couldn't find hydrolized yeast extract and I'm not sure if that would make a difference. "Sung (2005) reported the effects of Nogjungtang(a traditional Korean deer decoction) on growth, feed efficiency and organ growth in Sprague-Dawley male rats (5 and 10 weeks). Yang et al. (2003) reported that GSM containing Eleutherococcus senticosus had a growth stimulating effect on longitudinal bone growth in vivo and in vitro. Finally, Park et al. (2007) reported that HM-10 (an herbal medicine mixture) showed potential growth promoting capacity in rats, including longitudinal bone growth and GH releasing properties."<-some compounds and studies that may have an impact on height.
Role of cholesterol in the regulation of growth plate chondrogenesis and longitudinal bone growth.
"Inborn errors of cholesterol synthesis are associated with multiple systemic abnormalities, including skeletal malformations. The regulatory role of cholesterol during embryogenesis appears to be mediated by Shh, a signaling molecule in which activity depends on molecular events involving cholesterol. Based on this evidence, we hypothesized that cholesterol, by modifying the activity of Ihh (another of the Hedgehog family proteins) in the growth plate, regulates longitudinal bone growth. To test this hypothesis, we treated rats with AY 9944, an inhibitor of the final reaction of cholesterol synthesis. After 3 weeks, AY 9944 reduced the cumulative growth, tibial growth, and the tibial growth plate height of the rats. To determine whether cholesterol deficiency affects bone growth directly at the growth plate, we then cultured fetal rat metatarsal bones in the presence of AY 9944. After 4 days, AY 9944 suppressed metatarsal growth and growth plate chondrocyte proliferation and hypertrophy. The inhibitory effect on chondrocyte hypertrophy was confirmed by the AY 9944-mediated decreased expression of collagen X. Lastly, AY 9944 decreased the expression of Ihh in the metatarsal growth plate. We conclude that reduced cholesterol synthesis in the growth plate, possibly by altering the normal activity of Ihh, results in suppressed longitudinal bone growth and growth plate chondrogenesis."
"metatarsal bone rudiments cultured in the presence of 10 μM lovastatin for 4 days grew significantly less than the controls"
"impaired cholesterol synthesis in the growth plate is responsible for suppressed longitudinal bone growth."
Cholesterol influences the expression of indian hedgehog and indian hedgehog controls the regulation of chondrocyte hypertrophy.
P450 oxidoreductase expressed in rat chondrocytes modulates chondrogenesis via cholesterol- and Indian Hedgehog-dependent mechanisms.
"Cytochrome P450 oxidoreductase (POR) is the electron donor for microsomal cytochrome P450 enzymes and other non-P450 enzymes. Targeted deletion of POR expression in mice leads to a variety of embryonic defects, including bone abnormalities. In addition, POR mutations in humans are associated with impaired steroidogenesis and skeletal malformations. rat chondrocytes transfected with POR-specific short interfering RNAs exhibited decreased cell proliferation and differentiation and induced apoptosis. The reduced expression of POR in chondrocytes caused decreased intracellular cholesterol content. The addition of cholesterol in the culture medium prevented the POR small interfering RNA (siRNA)-mediated effects on chondrocyte proliferation, differentiation, and apoptosis. Because cholesterol is required for normal activity of the hedgehog proteins, we evaluated the effects of POR siRNAs on the expression of Indian hedgehog (Ihh), an important regulator of chondrogenesis. POR siRNA-transfected chondrocytes exhibited reduced Ihh expression, with such effect being neutralized by cholesterol. Lastly, recombinant human/mouse Ihh prevented the POR siRNA-mediated effects on chondrocyte proliferation, differentiation, and apoptosis. Our findings suggest that the bone malformations associated with defective POR activity are due to reduced cholesterol synthesis and, in turn, reduced Ihh expression in chondrocytes."
"the targeted inhibition of cholesterol synthesis in cultured metatarsal bones (through the activity of an inhibitor of 7-dehydrocholesterol reductase) results in suppressed longitudinal bone growth, chondrocyte proliferation, and chondrocyte hypertrophy"
"retinoic acid inhibits longitudinal growth of cultured rat metatarsal bones by suppressing chondrocyte proliferation, hypertrophy, and matrix synthesis "
"Dispatched1 (Disp1){down in LSJL} is required for the release of cholesterol modified hedgehog (Hh) proteins from producing cells. We investigated the role of Disp1 in Indian hedgehog (Ihh) signaling in the developing bone bypassing the lethality of the Disp1(C829F) allele at early somite stages through the supply of non-cholesterol modified Sonic hedgehog (N-Shh). The long bones that develop in the absence of wild-type Disp1, while clearly shorter, have a juxtaposition of proliferating and non-proliferating hypertrophic chondrocytes that is markedly more normal in organization than those of ihh null mutants. Direct analysis of Ihh trafficking in the target field demonstrates that Ihh is distributed well beyond Ihh expressing cells though the range of movement and signaling action is more restricted than in wild-type long bones. Consequently, a PTHrP-Ihh feedback loop is established, but over a shorter distance, reflecting the reduced range of Ihh movement. These analyses of the Disp1(C829F) mutation demonstrate that Disp1 is not absolutely required for the paracrine signaling role of Ihh in the skeleton. However, Disp1 is critical for the full extent of signaling within the chondrocyte target field and consequently the establishment of a normal skeletal growth plate."
"TGFβ2 appears to be required for Sonic hedgehog (Shh), a surrogate for Ihh-mediated effects in vitro, but the growth of bones is not significantly affected in TGFβ2 mutants "
"Hh ligands undergo two lipid modifications; addition of a C-terminal cholesterol moiety in conjunction with cleavage of the precursor protein to its active signaling form, and a covalent attachment of an N-terminal palmitate. Each ligand signals through a single membrane receptor protein, patched1 (Ptch1), Hh-Ptch1 binding leads to the derepression of the seven-pass membrane protein smoothened (Smo), and pathway activation in the responsive cell. Interestingly, paracrine signaling by cholesterol modified hh ligands requires the action of a Ptch1 related membrane protein, Disp1, within Hh producing cells"
Regulation of growth plate chondrocytes by 1,25-dihydroxyvitamin D3 requires caveolae and caveolin-1.
"1,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] regulates endochondral ossification in part through membrane-associated mechanisms, including protein kinase C (PKC) signaling activated by a membrane-associated 1alpha,25(OH)(2)D(3)-binding protein, ERp60. We tested the hypothesis that caveolae are required for 1alpha,25(OH)(2)D(3) action and play an important role in regulating chondrocyte biology and growth plate physiology.
Rat costochondral chondrocytes were examined for caveolae by transmission electron microscopy of cultured cells and of cells in situ. Western blots and confocal microscopy were used to detect caveolae proteins including caveolin-1 (Cav-1) and 1alpha,25(OH)(2)D(3) receptors. Caveolae cholesterol was depleted with beta-cyclodextrin (CD) and effects of 1alpha,25(OH)(2)D(3) on PKC, DNA synthesis, alkaline phosphatase, and proteoglycan production determined. Chondrocytes from Cav-1(-/-) and C57BL/6 wildtype mice were also treated with 1alpha,25(OH)(2)D(3). Epiphyses and costochondral junctions of 8-week-old male Cav-1(-/-) and wildtype mice (N = 8) were compared by histomorphometry and microCT. Data were analyzed by ANOVA and Bonferroni for posthoc comparisons.
Growth zone chondrocytes had caveolae and Cav-1, -2, and -3{up in LSJL}. Resting zone chondrocytes, which do not exhibit a rapid 1alpha,25(OH)(2)D(3)-dependent increase in PKC activity, also had these caveolins, but caveolae were larger and fewer in number. ERp60 but not VDR co-localized with Cav-1 in plasma membranes and in lipid rafts. CD-treatment blocked 1alpha,25(OH)(2)D(3) effects on all parameters tested. The Cav-1(-/-) cells did not respond to 1alpha,25(OH)(2)D(3), although 1alpha,25(OH)(2)D(3) increased PKC, alkaline phosphatase, and [(35)S]-sulfate incorporation in wildtype C57BL/6 cells. Histology and microCT showed that Cav-1(-/-) growth plates were longer and had more hypertrophic cells in each column. Growth plate changes were reflected in the metaphysis.
The membrane-mediated effects of 1alpha,25(OH)(2)D(3) require caveolae and Cav-1, and Cav-1 deficiency results in altered growth plate physiology."
"ERp60[receptor for Vitamin D] is required for protein kinase C α (PKCα) signaling in growth plate chondrocytes"
"the mechanism involves rapid activation of phospholipase A2 (PLA2) through PLA2-activating protein (PLAA). Arachidonic acid released by PLA2 can activate PKC directly. Prostaglandin produced through cyclooxygenase-1 binds its EP-1 receptor to activate PKC as well. In addition, lysophospholipid produced by PLA2 activates phospholipase C (PLC), resulting in formation of diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). DAG binds PKC and translocates it to the plasma membrane; IP3 initiates the release of Ca2+ from the endoplasmic reticulum, which can then serve as a co-factor for PKC activation."
"Specialized cholesterol-rich regions of the plasma membrane called lipid rafts/caveolae provide structural scaffolding for signal transduction and a principal component of caveolae that serves the scaffolding function, caveolin-1, was recently implicated in the function of membrane-associated estrogen receptors. The nuclear VDR has also been found in lipid rafts/caveolae, suggesting the hypothesis that these membrane microdomains play an important role in the mechanism of 1α,25(OH)2D3 action."
"ERp60 co-localized with lipid rafts"
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