trichostatin-a and Hypertrophy

To demonstrate the existence of mesenchymal stem cells (MSCs) in ligamentum flavum (LF) and their pathogenic role in LF hypertrophy.. To isolate and characterize LF-derived MSCs and their response to transforming growth factor-beta 1 (TGF-β1) and trichostatin A (TSA), a histone deacetylase inhibitor (HDACi).. LF is a connective tissue, of which hypertrophic changes induce spinal stenosis. The pathogenic role of TGF-β1 in spinal stenosis has been implicated. TSA has been shown to suppress TGF-β1-induced alpha-smooth muscle actin (α-SMA), type I and III collagen synthesis in a variety of cells. MSCs have been isolated from a variety of adult tissues, except LF. Whether MSCs exist in LF and their response to TGF-β1 and TSA is not clear.. The MSCs from LF were isolated and cultured. Their phenotypic character, linage differentiation potential, and response to TGF-β1 and TSA were analyzed.. LF-derived MSCs have the similar profile of surface markers as bone marrow MSCs. They were demonstrated to have the potential to be differentiated into osteoblasts, adipocytes, and chondrocytes. Administration of TGF-β1 stimulated cell proliferation, enhanced the gene expression of type I and III collagen, and increased the gene expression and protein level of α-SMA. TSA blocked the fibrogenic effects of TGF-β1.. The current results demonstrated the isolation of MSCs from LF. The cellular response to TGF-β1 implied that these cells might play an important role in the pathogenesis of LF hypertrophy. TSA, which blocks the effects of TGF-β1, may be a potent therapeutic choice for inhibiting LF hypertrophy.

Topics: Actins; Adipocytes; Blotting, Western; Cell Differentiation; Cell Proliferation; Cells, Cultured; Chondrocytes; Collagen; Gene Expression; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Hypertrophy; Immunohistochemistry; Ligamentum Flavum; Mesenchymal Stem Cells; Muscle, Smooth; Osteoblasts; Osteopontin; Reverse Transcriptase Polymerase Chain Reaction; Transforming Growth Factor beta1

Yeast silent information regulator 2 (Sir2), a nicotinamide adenine dinucleotide-dependent histone deacetylase (HDAC) and founding member of the HDAC class III family, functions in a wide array of cellular processes, including gene silencing, longevity, and DNA damage repair. We examined whether or not the mammalian ortholog Sir2 affects growth and death of cardiac myocytes. Cardiac myocytes express Sir2alpha predominantly in the nucleus. Neonatal rat cardiac myocytes were treated with 20 mmol/L nicotinamide (NAM), a Sir2 inhibitor, or 50 nmol/L Trichostatin A (TSA), a class I and II HDAC inhibitor. NAM induced a significant increase in nuclear fragmentation (2.2-fold) and cleaved caspase-3, as did sirtinol, a specific Sir2 inhibitor, and expression of dominant-negative Sir2alpha. TSA also modestly increased cell death (1.5-fold) but without accompanying caspase-3 activation. Although TSA induced a 1.5-fold increase in cardiac myocyte size and protein content, NAM reduced both. In addition, NAM caused acetylation and increases in the transcriptional activity of p53, whereas TSA did not. NAM-induced cardiac myocyte apoptosis was inhibited in the presence of dominant-negative p53, suggesting that Sir2alpha inhibition causes apoptosis through p53. Overexpression of Sir2alpha protected cardiac myocytes from apoptosis in response to serum starvation and significantly increased the size of cardiac myocytes. Furthermore, Sir2 expression was increased significantly in hearts from dogs with heart failure induced by rapid pacing superimposed on stable, severe hypertrophy. These results suggest that endogenous Sir2alpha plays an essential role in mediating cell survival, whereas Sir2alpha overexpression protects myocytes from apoptosis and causes modest hypertrophy. In contrast, inhibition of endogenous class I and II HDACs primarily causes cardiac myocyte hypertrophy and also induces modest cell death. An increase in Sir2 expression during heart failure suggests that Sir2 may play a cardioprotective role in pathologic hearts in vivo.

Topics: Acetylation; Alkaloids; Animals; Apoptosis; Atrial Natriuretic Factor; Benzamides; Benzophenanthridines; Cell Nucleus; Cell Size; Cell Survival; Cells, Cultured; Culture Media, Serum-Free; Cysteine Proteinase Inhibitors; Dogs; Gene Silencing; Genes, Dominant; Genes, p53; Heart Failure; Heart Ventricles; Hydroxamic Acids; Hypertrophy; Hypertrophy, Left Ventricular; Longevity; Mice; Myocytes, Cardiac; Naphthols; Niacinamide; Phenanthridines; Protein Processing, Post-Translational; Rats; Rats, Wistar; Recombinant Fusion Proteins; Sirtuin 1; Sirtuins; Transcription, Genetic; Tumor Suppressor Protein p53