Anurupa Ghosh

Class II histone deacetylases (HDACs) are important in regulation of gene transcription during T cell development. However, our understanding of their cell-specific functions is limited. In this study, we reveal that class IIa Hdac4 and Hdac7 (Hdac4/7) are selectively induced in transcription, guiding the lineage-specific differentiation of mouse T-helper 17 (Th17) cells from naive CD4 ⁺ T cells. Importantly, Hdac4/7 are functionally dispensable in other Th subtypes. Mechanistically, Hdac4 interacts with the transcription factor (TF) JunB, facilitating the transcriptional activation of Th17 signature genes such as Il17a/f . Conversely, Hdac7 collaborates with the TF Aiolos and Smrt/Ncor1-Hdac3 corepressors to repress transcription of Th17 negative regulators, including Il2 , in Th17 cell differentiation. Inhibiting Hdac4/7 through pharmacological or genetic methods effectively mitigates Th17 cell–mediated intestinal inflammation in a colitis mouse model. Our study uncovers molecular mechanisms where HDAC4 and HDAC7 function distinctively yet cooperatively in regulating ordered gene transcription during Th17 cell differentiation. These findings suggest a potential therapeutic strategy of targeting HDAC4/7 for treating Th17-related inflammatory diseases, such as ulcerative colitis.

Oxidative stress-mediated damage is often a downstream result of Parkinson’s disease (PD), which is marked by sharp decline in dopaminergic neurons within the nigrostriatal regions of the brain, accounting for the symptomatic motor deficits in patients. Regulating the level of oxidative stress may present a beneficial approach in preventing PD pathology. Here, we assessed the efficacy of a nicotinamide adenine phosphate (NADPH) oxidase (NOX) inhibitor, an exogenous reactive oxygen species (ROS) regulator synthesized by Aptabio therapeutics with the specificity to NOX-1, 2 and 4. Utilizing N27 rat dopaminergic cells and C57Bl/6 mice, we confirmed that the exposures of alpha-synuclein preformed fibrils (PFF) induced protein aggregation, a hallmark in PD pathology. In vitro assessment of the novel compound revealed an increase in cell viability and decreases in cytotoxicity, ROS, and protein aggregation (Thioflavin-T stain) against PFF exposure at the optimal concentration of 10 nM. Concomitantly, the oral treatment alleviated motor-deficits in behavioral tests, such as hindlimb clasping, rotarod, pole, nesting and grooming test, via reducing protein aggregation, based on rescued dopaminergic neuronal loss. The suppression of NOX-1, 2 and 4 within the striatum and ventral midbrain regions including Substantia Nigra compacta (SNc) contributed to neuroprotective/recovery effects, making it a potential therapeutic option for PD.

Oxidative stress-mediated damage is often a downstream result of Parkinson’s disease (PD), which is marked by sharp decline in dopaminergic neurons within the nigrostriatal regions of the brain, accounting for the symptomatic motor deficits in patients. Regulating the level of oxidative stress may present a beneficial approach in preventing PD pathology. Here, we assessed the efficacy of a nicotinamide adenine phosphate (NADPH) oxidase (NOX) inhibitor, an exogenous reactive oxygen species (ROS) regulator synthesized by Aptabio therapeutics with the specificity to NOX-1, 2, and 4. Utilizing N27 rat dopaminergic cells and C57Bl/6 mice, we confirmed that the exposures of alpha-synuclein preformed fibrils (PFF) induced protein aggregation, a hallmark in PD pathology. In vitro assessment of the novel compound revealed an increase in cell viability and decreases in cytotoxicity, ROS, and protein aggregation (Thioflavin-T stain) against PFF exposure at the optimal concentration of 10nM. Concomitantly, the oral treatment alleviated motor deficits in behavioral tests, such as hindlimb clasping, rotarod, pole, nesting, and grooming test, via reducing protein aggregation, based on rescued dopaminergic neuronal loss. The suppression of NOX-1, 2, and 4 within the striatum and ventral midbrain regions including SNc contributed to neuroprotective/recovery effects, making it a potential therapeutic option for PD.

Parkinson’s disease (PD) is a progressive neurodegenerative motor disorder without an available therapeutic to halt the formation of Lewy bodies for preventing dopaminergic neuronal loss in the nigrostriatal pathway. Since oxidative-stress-mediated damage has been commonly reported as one of the main pathological mechanisms in PD, we assessed the efficacy of a novel NOX inhibitor from AptaBio Therapeutics (C-6) in dopaminergic cells and PD mouse models. The compound reduced the cytotoxicity and enhanced the cell viability at various concentrations against MPP+ and α-synuclein preformed fibrils (PFFs). Further, the levels of ROS and protein aggregation were significantly reduced at the optimal concentration (1 µM). Using two different mouse models, we gavaged C-6 at two different doses to the PD sign-displaying transgenic mice for 2 weeks and stereotaxically PFF-injected mice for 5 weeks. Our results demonstrated that both C-6-treated mouse models showed alleviated motor deficits in pole test, hindlimb clasping, crossbeam, rotarod, grooming, and nesting analyses. We also confirmed that the compound treatment reduced the levels of protein aggregation, along with phosphorylated-α-synuclein, in the striatum and ventral midbrain and further dopaminergic neuronal loss. Taken together, our results strongly suggest that NOX inhibition can be a potential therapeutic target for PD.

Emerging evidence indicates that cellular senescence could be a critical inducing factor for aging-associated neurodegenerative disorders. However, the involvement of cellular senescence remains unclear in Parkinson’s disease (PD). To determine this, we assessed the effects of α-synuclein preformed fibrils (α-syn PFF) or 1-methyl-4-phenylpyridinium (MPP⁺) on changes in cellular senescence markers, employing α-syn PFF treated-dopaminergic N27 cells, primary cortical neurons, astrocytes and microglia and α-syn PFF-injected mouse brain tissues, as well as human PD patient brains. Our results demonstrate that α-syn PFF-induced toxicity reduces the levels of Lamin B1 and HMGB1, both established markers of cellular senescence, in correlation with an increase in the levels of p21, a cell cycle-arrester and senescence marker, in both reactive astrocytes and microglia in mouse brains. Using Western blot and immunohistochemistry, we found these cellular senescence markers in reactive astrocytes as indicated by enlarged cell bodies within GFAP-positive cells and Iba1-positive activated microglia in α-syn PFF injected mouse brains. These results indicate that PFF-induced pathology could lead to astrocyte and/or microglia senescence in PD brains, which may contribute to neuropathology in this model. Targeting senescent cells using senolytics could therefore constitute a viable therapeutic option for the treatment of PD.

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