Tuesday, June 14, 2011

Grow Taller by Increasing Chromatin Acetylation?

Recently, we discovered that chromatin hyperacetylation was critical in inducing SOX9 transcription activity.  Stimulation of histone acetyltransferase or inhibition of histone deactylase may be a way to grow taller.  Low levels of chromatin acetylation results in less of the ECM genes aggrecan and COL2A1 which may interfere with optimal growth.

Chromatin hyperacetylation is an epigentic mechanism.  Epigenetics can be transferred between generations.  Transcription states are heritable.  The status of the parent at that particular moment may affect a child's development.  Other examples of epigentics are telomere length and DNA Methylation Status.

How does chromatin acetylation on SOX9 affect height and how do we increase chromatin acetylation?

Histone acetylation influences the activity of Sox9-related transcriptional complex.

"From the mesenchymal condensation of chondroprogenitors to the hypertrophic maturation of chondrocytes, chondrogenesis is sequentially regulated by cross-talk among transcription factors, growth factors, and chromatin structure{altering chromatin structure can alter chondrogenesis}. The master transcription factor Sry-type HMG box (Sox) 9 has an essential role in the expression of chondrogenic genes through the association with Sox9-binding sites on its target genes{thus to grow taller it's essential that Sox9 is working properl}. Several transcription factors and coactivators, such as Scleraxis/E47 and p300, cooperatively modulate the Sox9-dependent transcription by interacting with Sox9. The Sox9-related transcriptional apparatus activates its target gene expression through p300-mediated histone acetylation on chromatin. The transforming growth factor (TGF)-β superfamily also plays a key role in chondrocyte differentiation. The TGF-β-regulated Smad3/4 complex activates Sox9-dependent transcription on chromatin by associating with Sox9 itself, and by recruiting p300 onto Sox9[thus TGF-Beta may help with Sox9 transcription, note LSJL increases TGF-Beta levels]. The epigenetic status including histone modification and chromatin structure, directly influences Sox9-regulated chondrocyte differentiation."

The degree of chromatin folding affects transcriptional activity and less folding is better for activating transcription activity.

"Protein kinase A-induced phosphorylation of Sox9 enhances Sox9-dependent transcription by increasing the DNA-binding affinity of Sox9. On the other hand, Sox9 activity is suppressed by PIAS1-mediated sumoylation of Sox9. The ubiquitin-proteasome pathway also inhibits Sox9 transcriptional activity by inducing the degradation of Sox9"

"In the absence of Sox5/6, sclerotome MSCs are prevented from differentiating into chondrocytes, and switch their fate to Scx-expressing tendon/ligament progenitors"

"The MYST family coactivator Tip60, which mainly acetylates H4, increases Sox9/Sox5-dependent Col2a1 transcription by associating with Sox9 on chromatin"

"Sox5/6 may stabilize Sox9 on its binding site through the bending of DNA and thereby stimulate Sox9-regulated gene expression"

"Fibroblast growth factor (FGF) 1, FGF2, and insulin-like growth factor 1 up-regulate the expression of Sox9"

"Histone deacetylase (HDAC) inhibitors, including trichostatin A (TSA) and FK228, have the synergistic potential to induce Sox9 expression via enhanced recruitment of nuclear factor Y (NF-Y) to the proximal promoter of Sox9"

"IL-1βtreatment down-regulates Sox9 transactivation by a reduction of Sp1 binding to the Sox9 promoter"

BMP-2 induces histone hyperacetylation on Chromatin in Sox9.  This could be why too much BMP-2 reduces height growth.

"the BMP-2 inhibitor Noggin represses Sox9 expression in limb bud chondrogenic precursors while
inducing the ligament/tendon-specific transcription factor Scx"

"the histone acetyltransferase (HAT) activity of p300 has the potential to facilitate transcriptional activity by modulating the chromatin structure. In chondrogenesis, p300 stimulates transcription factor-mediated chromatin disruption. The CH3 domain of coactivator p300 directly associates with the C-terminal PQ-rich transactivation domain of Sox9, and activates Sox9-dependent transcription in chondrogenesis"

"Smad3 also stabilized the association between Sox9 and p300 by forming a transcriptional apparatus with Sox9 and p300"

"the bHLH transcription factor Scx{up in LSJL} and its partner E47 cooperatively stimulated Sox9-dependent transcription through the formation of a transcriptional complex with Sox9 and p300"

"Sox9 interacts with the Med12/Trap230 subunit of the mediator complex to stimulate RNA polymerase II-dependent transcription in chondrocytes. Med12/Trap230 acts as an essential bridging factor between Sox9 and the RNA polymerase II transcriptional machinery. Peroxisome proliferator activated receptorγcoactivator 1α(Pgc1α), which is involved in gluconeogenesis, stimulates Sox9- dependent transcription including Col2a1 and COMP expression via direct association with Sox9. Sox9 and the homeobox transcription factor Barx2{up} cooperatively bind to adjacent sites in the Col2a1 enhancer, and regulate chondrogenesis during limb development"

"histone hyperacetylation using the HDAC inhibitor TSA enhanced Sox9-regulated cartilage matrix gene expressions (COL2A1 and aggrecan) in human chondrocytes"

Being transgenic in Sox9 results in dwarfism.

Interactions between Sox9 and beta-catenin control chondrocyte differentiation.

"Here we show the existence of physical and functional interactions between beta-catenin and Sox9, a transcription factor that is required in successive steps of chondrogenesis. In vivo, either overexpression of Sox9 or inactivation of beta-catenin in chondrocytes of mouse embryos produces a similar phenotype of dwarfism with decreased chondrocyte proliferation, delayed hypertrophic chondrocyte differentiation, and endochondral bone formation[thus the best way to optimize Sox9 would be to find the equilibrium quantity of BMP-2]. Furthermore, either inactivation of Sox9 or stabilization of beta-catenin in chondrocytes also produces a similar phenotype of severe chondrodysplasia. Sox9 markedly inhibits activation of beta-catenin-dependent promoters and stimulates degradation of beta-catenin by the ubiquitination/proteasome pathway[too much Sox9 inhibits activation of Beta-Catenin so a way to counteract the dwarfism caused by too much Sox9 you'd want to stimulate more production of Beta-Catenin]. Likewise, Sox9 inhibits beta-catenin-mediated secondary axis induction in Xenopus embryos. Beta-catenin physically interacts through its Armadillo repeats with the C-terminal transactivation domain of Sox9. We hypothesize that the inhibitory activity of Sox9 is caused by its ability to compete with Tcf/Lef for binding to beta-catenin, followed by degradation of beta-catenin. Our results strongly suggest that chondrogenesis is controlled by interactions between Sox9 and the Wnt/beta-catenin signaling pathway."

"In the canonical Wnt pathway, binding of secreted Wnts to the Frizzled family of cell surface receptors inactivates Gsk3-β, resulting in stabilization and nuclear translocation of β-catenin and activation of Wnt target genes. The noncanonical pathways also signal through the Frizzled receptors. The planar cell polarity pathway activates the rho family of GTPases and the Jun N-terminal kinase, and modifies cytoskeletal organization and epithelial cell polarization. The Wnt/Ca2+ pathway stimulates the intracellular increase of Ca2+ through activation of protein kinase C and calmodulin-dependent kinase II."<-Lithium does this too.
"In vitro studies of chondrogenic mesenchymal cells in micromass cultures show that LiCl, which inhibits Gsk3-β and mimics canonical Wnt pathway activation, or a proteasome inhibitor, which stabilizes β-catenin, as well as overexpression of stβ-catenin, markedly inhibit expression of the major chondrocyte marker Col2a1, suggesting that β-catenin inhibits overt chondrocyte differentiation"<-Thus increasing Lithium levels may be a way to compensate for increasing Sox9 levels.

"Expression of the Cyclin D1 gene and the activity of its promoter are increased by the β-catenin/Tcf-Lef complex. Sox9 overexpression in chondrocytes in vivo induces a marked down-regulation of Cyclin D1. Sox9 also inhibits the β-catenin-mediated increase in Cyclin D1 promoter activity"<-It may be best to just find a way to directly stimulate Cyclin D1 expression.

"Overexpression of Sox9 in committed chondrogenic mesenchymal cells did not affect cell viability (data not shown) as well as the timing and the overall size of mesenchymal condensations, indicating that although Sox9 is required for chondrogenic mesenchymal condensations, a small amount of additional Sox9 has no effect on chondroprogenitors in vivo. Moreover, in Sox9-overexpressing embryos, overt differentiation into chondrocytes of cells present in mesenchymal condensations occurred normally."

"Cyclin D1 controls progression through the G1 phase of the cell cycle, and its expression is strictly regulated by transcriptional mechanisms. In growth plates, Cyclin D1 is specifically expressed in proliferating chondrocytes"<-thus being transgenic in Cyclin D1 may enable more chondrocyte proliferation.

"Sox9 also controls chondrocyte proliferation by inhibition of Cyclin D1 expression."<-Sox9 is required for mesenchymal differentiation into chondrocytes but it also inhibits chondrocyte proliferation by inhibiting Cyclin D1.

"This small additional amount of Sox9 is sufficient to produce a very abnormal skeletal phenotype."<-thus it is crucial not to increase chromatin acetylation unless you're deficient.

"Expression of the Cyclin D1 gene and the activity of its promoter are increased by the β-catenin/Tcf-Lef complex."

Here's a study on the HMGA2 gene which is related to chromatin activation and affects height:

HMGA2, MicroRNAs, and Stem Cell Aging

"a chromatin-associated protein, HMGA2, [is linked to] development, height, and mouse stem cell aging during late fetal development and young adulthood"<-Thus Chromatin may be linked to height as well.

"identifies the chromatin-associated protein HMGA2 as a developmental regulator of stem cell self-renewal"

"an association between common alleles of SNPs linked to HMGA2 and human height"

"A spontaneous mutation of the Hmga2 gene has been previously shown to result in the murine pygmy phenotype, which includes reduced adult size. Meanwhile, transgenic mice that overexpress a wild-type Hmga2 gene or a truncated variant without the 3′ UTR exhibit gigantism. This latter Hmga2 allele is of interest because the 3′ UTR truncation removes the let-7 binding sites, thereby abrogating the repression of Hmga2 by let-7. Furthermore, a germline chromosomal inversion that results in a similarly truncated human HMGA2 gene was identified in a boy with severe overgrowth. The HMGA2-linked SNPs that are most strongly associated with height are known to lie within the 3′ UTR of HMGA2, suggesting that the height-influencing genetic events linked to these SNPs may influence let-7 binding"<-Thus we should analyze let-7 and it's effect on height growth.

Conclusion:  Increasing chromatin acetylation may be a way to grow taller if you are deficient.  The best way to do so is via BMP-2 but genetic expression of Sox9 and Beta-Catenin must be carefully monitored.  Increasing Beta-Catenin levels may be possible with Lithium which stabilizes Beta-Catenin.  Instances of too high levels of Beta-Catenin have not been found to cause dwarfism however.  Although, there is likely a limited number of Beta-Catenin to stabilize.  However, increasing Sox9 activation may be viable as long as there is more Beta-Catenin activation in the system to ensure proper functioning of the Cyclin D1 gene to ensure proper chondrocyte proliferation.

Transcriptional regulation of chondrogenesis by coactivator Tip60 via chromatin association with Sox9 and Sox5.

"Here, we report on the characterization of a Tat interactive protein-60 (Tip60) as Sox9-associated protein identified in a yeast two-hybrid screen. Both in vitro and in vivo assays confirmed the specificity of interactions between Sox9 and Tip60 including the existence of an endogenous complex containing both polypeptides in chondrocytes. Gel shift assays showed the presence of a complex containing Sox9, Tip60 and the DNA of an enhancer region of the Col2a1 promoter. Reporter assays using a Col2a1 promoter with multimerized Col2a1 Sox9-binding sites indicated that Tip60 enhanced the transcriptional activity of Sox9. A larger Col2a1 promoter showed that Tip60 increased the activity of this promoter in the presence of both Sox9 and Sox5. Ectopic expression of Sox9 and transient-cotransfection with Tip60 in COS7 cells showed a more diffuse subnuclear colocalization, suggesting changes in the chromatin structure. Chromatin immunoprecipitation assays showed that Tip60, Sox9 and Sox5 associated with the same Col2a1 enhancer region. Consistent with a role of Tip60 in chondrogenesis, addition of Tip60 siRNA to limb-bud micromass cultures delayed chondrocyte differention. Tip60 enhances acetylation of Sox9 mainly through K61, 253, 398 residues; however, the K61/253/398A mutant of Sox9 still exhibited enhanced transcriptional activity by Tip60. Our results support the hypothesis that Tip60 is a coactivator of Sox9 in chondrocytes."

"Posttranslational modifications of nucleosomal histones have been proposed to influence chromatin structure and to create a code that is interpreted by positive and negative transcriptional regulators recognizing specific histone modifications. Histone acetylation, catalyzed by histone acetyl transferase (HAT), promotes gene transcription by relaxing the chromatin structure, thereby facilitating access of the transcriptional machinery to DNA target sequences. The transcription-activating effect of histone acetylation is counterbalanced by histone deacetylation, which favors chromatin condensation and transcriptional repression"

"[Tip60] acetylates histone H4, modulates DNA-damage response signaling, which is triggered by oncogenes, and controls cell cycle checkpoints and apoptosis"

"Tip60 is a tightly regulated transcriptional coactivator for androgen-, estrogen- and progesterone- receptors. It also acts as a coactivator of p53 in activation of the p21 promoter and has been found on c-Myc and NFKB target genes"


"Histone deacetylation 4 (HDAC4) nuclear-cytoplasmic shuttling, degradation, and translational repression plays a major role in [the growth plate]. Specifically, we suspect that HDAC4 functions as a negative regulator of chondrocyte hypertrophy by binding and inhibiting Runx 2/Cbfa1 expression in the nucleus. Runx 2/Cbfa1 is a transcription factor necessary for chondrocyte differentiation and hypertrophy.

Our overall hypothesis is that the relocation, degradation, and translational repression of HDAC4 control chondrocyte differentiation and are regulated by Ca2+/calmodulin kinase IV (CaMKIV), p38 MAP kinase, and microRNA-1 respectively at different zones in the growth plate.

Specific Aim 1: To determine whether activation of the Ca2+/calmodulin signaling pathway prevents nuclear entry of HDAC4 and enhances the binding of HDAC4 to the cytoplasmic binding protein 14-3-3. This may impair HDAC4-mediated inhibition of chondrocyte differentiation in the nucleus[so by stimulating calmodlulin you could stimulate chondrogenesis]. Hypothesis 1 is that HDAC4 nuclear- cytoplasmic shuttling controls chondrocyte differentiation and is dependent on the Ca2+/calmodulin signaling pathway.
Specific Aim 2: To determine whether: 2a) caspases degrade HDAC4; 2b) p38 MAPK regulates expression or activity of capsases 2 and 3; 2c) Runx2 expression is dependent on p38 MAPK by in situ hybridization in p38 MAPK defective and constitutively activated MKK6 mouse growth plates. Project 2b will be tested using active MKK6 to elevate p38 and dominant negative p38 MAPK to repress p38. Hypothesis 2 is that HDAC4 degradation is regulated by P38 MAPK by increasing expression of caspases 2 and 3.
Specific Aim 3: To determine whether: 3a) the spatio-temporal distribution of specific miRNA-1 is different during growth plate development; 3b) miRNA-1 downregulates HDAC4 by repressing HDAC4 translation at 3' UTR in the chondrocytes; 3c) miRNA-1regulates chondrocyte proliferation and differentiation.
Hypothesis 3 is that microRNA-1 is involved in chondrocyte hypertrophy regulation by repressing HDAC4 translation. Delineating the physiological controls of the physis could suggest possibilities for therapeutically manipulating endochondral bone growth by modulating the signaling pathways that govern the association of HDAC4 with Runx2. Prevention of leg length discrepancy, dwarfism, and other disorders of bone growth might also be possible once molecular triggers and stops affecting the growth plate are better understood."

Exposure to Valproic Acid Inhibits Chondrogenesis and Osteogenesis in Mid-Organogenesis Mouse Limbs.

"In utero exposure to valproic acid (VPA), a histone deacetylase (HDAC){so this tells us the important of histone deacetylation on height growth} inhibitor, causes neural tube, heart and limb defects. Valpromide (VPD), the amide derivative of VPA, does not inhibit HDAC activity and is a weak teratogen in vivo. The detailed mechanism of action of VPA as a teratogen is not known. The goal of these studies was to test the hypothesis that VPA disrupts regulation of the expression of genes that are critical in chondrogenesis and osteogenesis during limb development. Murine gestation day 12 embryonic forelimbs were excised and exposed to VPA or VPD in a limb bud culture system. VPA caused a significant concentration-dependent increase in limb abnormalities that was correlated with its HDAC inhibitory effect. The signaling of both Sox9 and Runx2, key regulators of chondrogenesis, was downregulated by VPA. In contrast, VPD had little effect on limb morphology and no significant effect on HDAC activity or the expression of marker genes. Thus, VPA exposure dysregulated the expression of target genes directly involved in chondrogenesis and osteogenesis in the developing limb. Disturbances in these signaling pathways are likely to be a consequence of HDAC inhibition since VPD did not affect their expression."

"VPA is an inhibitor of class I and II histone deacetylases (HDACs)"

"apicidin, MS-275, sodium butyrate and sodium salicylate{Sodium salicylate is present in some treatments, you may want to avoid it} are all HDAC inhibitors that induce defects of the axial skeleton in mice"

"the low dose VPA treatment group showed minimal effects on morphology, the limbs exposed to 1.8 or 3.6 mM VPA exhibited a marked decrease in growth and differentiation. The long bones were reduced in size, the staining of the carpalia was decreased and the metacarpals were short and thick."

"VPA exposure resulted in the downregulation of Sox9 mRNA expression by 1h in all VPA-exposed limbs"

The high mobility group protein HMGA2: a co-regulator of chromatin structure and pluripotency in stem cells?

"[HMGA2] proteins are abundant in pluripotent embryonic stem (ES) cells and most malignant human tumors, but are not detectable in normal somatic cells. They act both as activator and repressor of gene expression, and most likely facilitate DNA architectural changes during formation of specialized nucleoprotein structures at selected promoter regions. For example, HMGA2 is involved in transcriptional activation of certain cell proliferation genes, which likely contributes to its well-established oncogenic potential during tumor formation. However, surprisingly little is known about how HMGA proteins bind DNA packaged in chromatin and how this affects the chromatin structure at a larger scale. Experimental evidence suggests that HMGA2 competes with binding of histone H1 in the chromatin fiber. This could substantially alter chromatin domain structures in ES cells and contribute to the activation of certain transcription networks. HMGA2 also seems capable of recruiting enzymes directly involved in histone modifications to trigger gene expression. Furthermore, it was shown that multiple HMGA2 molecules bind stably to a single nucleosome core particle whose structure is known. How these features of HMGA2 impinge on chromatin organization inside a living cell is unknown. In this commentary, we propose that HMGA2, through the action of three independent DNA binding domains, substantially contributes to the plasticity of ES cell chromatin and is involved in the maintenance of a un-differentiated cell state."

"HMGA2 [controls] (stem) cell proliferation and the development of adipose tissue."

"During activation of E2F1{down in LSJL}, HMGA2 replaces the histone deacetylase from DNA and recruits histone acetylase, thus leading to sustained gene expression from this locus"  E2F1 binds to Sp1 which binds to Sox9(Source: String DB).

"ERCC1 [is repressed] through binding of HMGA2 to a particular AT-rich site within the promoter region" ERCC1 is several steps removed from Sox9(Source: String DB).

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