UCH-L1 Inhibition Involved in CREB Dephosphorylation in Hippocampal Slices

Puerarin improves the comorbidity of chronic pain and depression by binding with Bax and reducing mitochondrial dysfunction

Depression is a common comorbidity of chronic pain. The comorbidity of pain and depression causes longer symptoms and poorer patient prognosis. Periaqueductal gray (PAG) is the key region for the regulation of pain and depression. Puerarin (Pue) is a natural isoflavone compound that has a neuroprotective effect, but the mechanisms on the comorbidity of chronic pain and depression remain unclear. In this study, the spared nerve injury (SNI) produced mechanical allodynia and depressive-like behaviors and elevated the neurological damage in ventrolateral (vl) PAG. Meanwhile, at the 8 weeks following injury, mitochondrial dysfunctions including the dysregulated protein levels, the decreased Mn-SOD activity and the reduced ATP contents were observed in vlPAG of SNI model mice. Pue administration improved mechanical pain, motor coordination, and depression-like behaviors, decreased the neuronal activity and neuroinflammation, and elevated the mitochondrial function in vlPAG. Database analysis and experimental assay showed that Pue bound with Bax at the affinity of 2.4 ± 0.1 μM via D102 residue, and decreased Bax level in vlPAG of mice and in primary astrocytic cells. In addition, Pue also recovered levels of mitochondrial membrane potential and reactive oxygen species, and decreased inflammation in primary astrocytic cells. These results suggest that Pue improves the comorbidity of chronic pain and depression by targeting Bax and reducing mitochondrial dysfunction in vlPAG. This study may provide a theoretical basis for Pue application in improving the comorbidity of chronic pain and depression.

Alzheimer's disease and its treatment by different approaches: A review

Alzheimer's disease (AD) is a neurodegenerative disorder that impairs mental ability development and interrupts neurocognitive function. This neuropathological condition is depicted by neurodegeneration, neural loss, and development of neurofibrillary tangles and Aβ plaques. There is also a greater risk of developing AD at a later age for people with cardiovascular diseases, hypertension and diabetes. In the biomedical sciences, effective treatment for Alzheimer's disease is a severe obstacle. There is no such treatment to cure Alzheimer's disease. The drug present in the market show only symptomatic relief. The cause of Alzheimer's disease is not fully understood and the blood-brain barrier restricts drug efficacy are two main factors that hamper research. Stem cell-based therapy has been seen as an effective, secure, and creative therapeutic solution to overcoming AD because of AD's multifactorial nature and inadequate care. Current developments in nanotechnology often offer possibilities for the delivery of active drug candidates to address certain limitations. The key nanoformulations being tested against AD include polymeric nanoparticles (NP), inorganic NPs and lipid-based NPs. Nano drug delivery systems are promising vehicles for targeting several therapeutic moieties by easing drug molecules' penetration across the CNS and improving their bioavailability. In this review, we focus on the causes of the AD and their treatment by different approaches.

Enriched environment improves working memory impairment of mice with traumatic brain injury by enhancing histone acetylation in the prefrontal cortex

Working memory impairment is a common cognitive dysfunction after traumatic brain injury (TBI), which severely affects the quality of life of patients. Acetylcholine is a neurotransmitter which is closely related to cognitive functions. In addition, epigenetic modifications are also related to cognitive functions. A neurorehabilitation strategy, enriched environment (EE) intervention, has been widely used to improve cognitive impairment. However, studies of the mechanism of EE on cholinergic system and epigenetic modifications in mouse with TBI have not been reported yet. In this paper, a mouse model with traumatic frontal lobe injury was established, and the mechanism on EE for the mice with TBI was explored. It was found that EE could improve Y-maze performance of mice with TBI, the function of cholinergic system, and the imbalance of acetylation homeostasis in the prefrontal cortex of contralateral side of TBI. In addition, EE also could increase the level of CREB binding protein and histones H3 acetylation at ChAT gene promoter region in the prefrontal cortex of contralateral side of TBI. These indicate that EE has an important effect on the improvement of working memory impairment and the underlying mechanism may involve in histones H3 acetylation at ChAT gene promoter regions in the prefrontal cortex.

UCH-L1 Inhibition Suppresses tau Aggresome Formation during Proteasomal Impairment

In conditions of proteasomal impairment, the damaged or misfolded proteins, collectively known as aggresome, can accumulate in the perinuclear space and be subsequently eliminated by autophagy. Abnormal aggregation of microtubule-associated protein tau in the cytoplasm is a common neuropathological feature of tauopathies. The deficiency in ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), a proteasomal deubiquitinating enzyme, is closely related to tau aggregation; however, the associated mechanisms remain unclear. Here, we showed that UCH-L1 inhibition interrupts proteasomal impairment-induced tau aggresome formation. By reducing the production of lysine (K63)-linked ubiquitin chains, UCH-L1 inhibition decreases HDAC6 deacetylase activity and attenuates the interaction of HDAC6 and tau protein, finally leading to tau aggresome formation impairment. All these results indicated that UCH-L1 plays a key role in the process of tau aggresome formation by regulating HDAC6 deacetylase activity and implied that UCH-L1 may act as a signaling molecule to coordinate the effects of the ubiquitin-proteasome system and the autophagy-lysosome pathway, which mediate protein aggregates degradation in the cytoplasm.