Inhibition of Histone Deacetylase 6 by Tubastatin A Attenuates the Progress of Osteoarthritis via Improving Mitochondrial Function.

Because chondrocytes are the only resident cells in articular cartilage, the steady state of these cells is important for the maintenance of joint function. In various osteoarthritis diseases, chondrocytes undergo a series of pathophysiologic changes, leading to the loss of chondrocytes and the degradation of extracellular matrix (ECM). This study found that Cytoplasmic localized histone deacetylase 6 (HDAC6) is up-regulated on the articular surface in a destabilization of the medial meniscus-induced mouse osteoarthritis model. Because HDAC6 is highly related to the acetylation of tubulin and the function of the microtubule system is closely related to material transport and signal transduction, the relationship between the expression level or activity of HDAC6 and the fate of chondrocytes in vitro and in vivo were confirmed. Primary chondrocytes overexpressing DNA-HDAC6 with plasmid were constructed in vitro, and HDAC6 inhibitor Tubastatin A was selected to inhibit HDAC6 enzyme activity in vivo and in vitro. Subsequently, mitochondrial spatial arrangement, degradation of ECM, and pathological changes in joint were defined. The results indicate that overexpression of HDAC6 causes mitochondrial dysfunction and promotes reactive oxygen species production, leading to degradation of ECM. Tubastatin A treatment after osteoarthritis ameliorates the degradation of cartilage and improves the microenvironment and function of the joint. HDAC6 may be targeted to treat osteoarthritis.

Sulforaphane induces autophagy by inhibition of HDAC6-mediated PTEN activation in triple negative breast cancer cells.

AIMS: To study the underlying mechanisms of sulforaphane, a natural histone deacetylase (HDAC) inhibitor, in inhibiting triple negative breast cancer cells growth and the therapeutic effects of combination of sulforaphane and doxorubicin in TNBC treatment. MATERIALS AND METHODS: The antineoplastic activity of sulforaphane was evaluated in MDA-MB-231, BT549 and MDA-MB-468 cells with MTT assay. Cell apoptosis was detected with Annexin V/PI double staining by Flow cytometry. Cell autophagy was detected with fluorescence microscope. The effects of Sulforaphane and Doxorubicin combination treatments on cells growth were determined with Chou-Talalay median effect/combination index (CI) model. mRNA and protein expression of genes were assayed respectively with real-time PCR and Western bloting. Protein-protein interaction was detected with co-immunoprecipation. Gene knock-down was performed with small interfere RNA. In vivo assay of combinational treatment with sulforaphane and doxorubicin was investigated in athymic nude mice bearing MDA-MB-231 xenografts. KEY FINDINGS: Results showed that sulforaphane inhibited cell growth and induced autophagy in MDA-MB-231, BT549 and MDA-MB-468 cells. Further study demonstrated that sulforaphane induced autophagy by down-regulating expression of HDAC6, which resulted in increased membrane translocation and acetylation modification of phosphatase and tensin homolog (PTEN). Sulforaphane and doxorubicin combination exhibited a synergistic inhibition on TNBC cells growth. In nude mice, the combination of sulforaphane and doxorubicin displayed a greater inhibitory effect on MDA-MB-231 xenografts growth as compared to either treatment alone. SIGNIFICANCE: Our study suggested that induction of autophagy by targeting HDAC6 in combination with chemotherapeutic reagent may provide a novel strategy for TNBC therapy.

3,4-Dihydroxyphenylethanol Assuages Cognitive Impulsivity in Alzheimer's Disease by Attuning HPA-Axis via Differential Crosstalk of α7 nAChR with MicroRNA-124 and HDAC6.

Cognitive impulsivity, a form of suboptimal cost-benefit decision making, is an illustrious attribute of an array of neurodegenerative diseases including Alzheimer's disease (AD). In this study, a delay discounting paradigm was used to assess the effect of 3,4-dihydroxyphenylethanol (DOPET) on cognitive impulsivity, in an oA42i (oligomeric amyloid ß1-42 plus ibotenic acid) induced AD mouse model, using a nonspatial T-maze task. The results depicted that oA42i administration elevated cognitive impulsivity, whereas DOPET treatment attenuated the impulsive behavior and matched the choice of the sham-operated controls. In addition, DOPET treatment has ameliorated the anxiety-like behavior in the oA42i-challenged mice. Probing the molecular signaling cascades underpinning these functional ramifications in the oA42i-challenged mice revealed reduced cholinergic (α7 nAChR; alpha 7 nicotinic acetylcholine receptor) function, dysregulated hypothalamic-pituitary-adrenal (HPA) axis (manifested by amplified glucocorticoid receptor expression and plasma corticosterone levels), and also aberrations in the neuroepigenetic (microRNA-124, HDAC6 (histone deacetylase 6), and HSP90 (heat-shock protein 90) expressions) as well as nucleocytoplasmic (importin-α1 expression and nuclear ultra-architecture) continuum. Nonetheless, DOPET administration ameliorated these perturbations and the observations were in line with that of the sham-operated mice. Further validation of the results with organotypic hippocampal slice cultures (OHSCs) confirmed the in vivo findings. We opine that HPA-axis attunement by DOPET might be orchestrated through the α7 nAChR-mediated pathway. Based on these outcomes, we posit that 3,4-dihydroxyphenylethanol might be a potential multimodal agent for the management of cognitive impulsivity and neuromolecular quagmire in AD.