Role of pericyte-derived SENP1 in neuronal injury after brain ischemia.

AIMS: SUMOylation is a posttranslational modification related to multiple human diseases. SUMOylation can be reversed by classes of proteases known as the sentrin/SUMO-specific proteases (SENPs). In the present study, we investigate the potential role of SENP1 in pericytes in the brain ischemia. METHODS: Pericyte-specific deletion of senp1 mice (Cspg4-Cre; senp1f/f ) were used for brain function and neuronal damage evaluation following brain ischemia. The cerebral blood vessels of diameter, velocity, and flux were performed in living mice by two-photon laser scanning microscopy (TPLSM). Biochemical analysis and immunohistochemistry methods were used to address the role and mechanism of pericyte-specific SENP1 in the pathological process of brain ischemia. A coculture model of HBVPs and HBMECs mimicked the BBB in vitro and was used to evaluate BBB integrity after glucose deprivation. RESULTS: Our results showed that senp1-specific deletion in pericytes did not affect the motor function and cognitive function of mice. However, the pericyte-specific deletion of senp1 aggravated the infarct size and motor deficit following focal brain ischemia. Consistently, the TPLSM data demonstrated that SENP1 deletion in pericytes accelerated thrombosis formation in brain microvessels. We also found that pericyte-specific deletion of senp1 exaggerated the neuronal damage significantly following brain ischemia in mice. Moreover, SENP1 knockdown in pericytes could activate the apoptosis signaling and disrupt the barrier integrity in vitro coculture model. CONCLUSIONS: Our findings revealed that targeting SENP1 in pericytes may represent a novel therapeutic strategy for neurovascular protection in stroke.

Functional coupling of Tmem74 and HCN1 channels regulates anxiety-like behavior in BLA neurons.

Anxiety disorders are the most prevalent psychiatric disorders, but their pathogenic mechanism remains poorly understood. Here, we report that transmembrane protein 74 (TMEM74), which contains two putative transmembrane domains and exhibits high levels of mRNA in the brain, is closely associated with the pathogenesis of anxiety disorders. TMEM74 was decreased in the serum of patients with anxiety and the basolateral amygdaloid nucleus (BLA) in chronic stress mice. Furthermore, genetic deletion of Tmem74 or selective knockdown of Tmem74 in BLA pyramidal neurons resulted in anxiety-like behaviors in mice. Whole-cell recordings in BLA pyramidal neurons revealed lower hyperpolarization-activated cation current (Ih) and greater input resistance and excitability in Tmem74-/- neurons than in wild-type neurons. Accordingly, surface expression of hyperpolarization-activated cyclic nucleotide-gated 1 (HCN1) channels was also lower in the BLA of Tmem74-/- mice. The Ih current blocker ZD7288 mimicked these effects in BLA pyramidal neurons in wild-type mice but not in Tmem74-/- mice. Consistent with the improvement in anxiety-like behaviors, Tmem74 overexpression restored HCN1 channel trafficking and pyramidal neuron excitability in the BLA of Tmem74-/- and chronic stress mice. Mechanistically, we demonstrate that interactions between Tmem74 and HCN1 are physiologically relevant and that transmembrane domain 1 (TM1) is essential for the cellular membrane localization of Tmem74 to enhance Ih. Together, our findings suggest that Tmem74 coupling with HCN1 acts as a critical component in the pathophysiology of anxiety and is a potential target for new treatments of anxiety disorders.

Cathepsin B inhibition ameliorates leukocyte-endothelial adhesion in the BTBR mouse model of autism.

AIMS: Autism spectrum disorder (ASD) is a wide range of neurodevelopmental disorders involving deficits in social interaction and communication. Unfortunately, autism remains a scientific and clinical challenge owing to the lack of understanding the cellular and molecular mechanisms underlying it. This study aimed to investigate the pathophysiological mechanism underlying leukocyte-endothelial adhesion in autism-related neurovascular inflammation. METHODS: Male BTBR T+tf/J mice were used as an autism model. The dynamic pattern of leukocyte-endothelial adhesion in mouse cerebral vessels was detected by two-photon laser scanning microscopy (TPLSM). Using FACS, RT-PCR, and Western blotting, we explored the expression of cell adhesion molecules, the mRNA expression of endothelial chemokine, the protein levels of cathepsin B, and inflammatory mediators. RESULTS: We found a significant increase in leukocyte-endothelial adhesion in BTBR mice, accompanied by elevated expression of the adhesion molecule neutrophils CD11b and endothelial ICAM-1. Our data further indicate that elevated neutrophil cathepsin B levels contribute to elevated endothelial chemokine CXCL7 levels in BTBR mice. The pharmacological inhibition of cathepsin B reverses the enhanced leukocyte-endothelial adhesion in the cerebral vessels of autistic mice. CONCLUSION: Our results revealed the prominent role of cathepsin B in modulating leukocyte-endothelial adhesion during autism-related neurovascular inflammation and identified a promising novel approach for autism treatment.

Calmodulin inhibitor ameliorates cognitive dysfunction via inhibiting nitrosative stress and NLRP3 signaling in mice with bilateral carotid artery stenosis.

AIMS: Vascular dementia (VaD) is a heterogeneous brain disorder for which there are no effective approved pharmacological treatments available. We aimed to evaluate the effect of calmodulin inhibitor, DY-9836, and its loaded nanodrug carrier system on cognitive impairment and gain a better understanding of the protective mechanisms in mice with bilateral carotid artery stenosis (BCAS). RESULTS: DY-9836 (0.5 or 1 mg/kg) or DY-9836 (0.25 mg/kg)-encapsulated polysialic acid-octadecylamine (PSA-ODA) micelles (PSA-ODA/DY) were given to BCAS mice for 4 weeks. Administration of DY-9836 or PSA-ODA/DY reduced escape latency in space exploration and working memory test compared with vehicle group. Vehicle-treated mice showed reduced phospho-CaMKII (Thr286/287) levels in the hippocampus, whereas partially restored by DY-9836 (1 mg/kg) or PSA-ODA/DY (0.25 mg/kg) treatment. In accordance with the pharmacological profile of DY-9836 observed during behavioral studies, experimental molecular and biochemical markers induced by BCAS, such as protein tyrosine nitration, Nod-like receptor protein 3 (NLRP3), caspase-1, and interleukin-1ß, were reduced by DY-9836 and PSA-ODA/DY treatment. CONCLUSIONS: These data disclose novel findings about the therapeutic potential of DY-9836, and its encapsulated nanodrug delivery system significantly enhanced the cognitive function via inhibitory effect on nitrosative stress and NLRP3 signaling in VaD mice.

Modulation of the unfolded protein response is the core of microRNA-122-involved sensitivity to chemotherapy in hepatocellular carcinoma.

The loss of microRNA-122 (miR-122) expression correlates to many characteristic properties of hepatocellular carcinoma (HCC) cells, including clonogenic survival, anchorage-independent growth, migration, invasion, epithelial-mesenchymal transition, and tumorigenesis. However, all of these findings do not sufficiently explain the oncogenic potential of miR-122. In the current study, we used two-dimensional differential in-gel electrophoresis to measure changes in the expression of thousands of proteins in response to the inhibition of miR-122 in human hepatoma cells. Several proteins that were upregulated on miR-122 inhibition were involved in the unfolded protein response (UPR) pathway. The overexpression of miR-122 resulted in the repression of UPR pathway activation. Therefore, miR-122 may act as an inhibitor of the chaperone gene expression and negatively regulate the UPR pathway in HCC. We further showed that the miR-122 inhibitor enhanced the stability of the 26S proteasome non-ATPase regulatory subunit 10 (PSMD10) through the up-regulation of its target gene cyclin-dependent kinase 4 (CDK4). This process may activate the UPR pathway to prevent chemotherapy-mediated tumor cell apoptosis. The current study suggests that miR-122 negatively regulates the UPR through the CDK4-PSMD10 pathway. The down-regulation of miR-122 activated the CDK4-PSMD10-UPR pathway to decrease tumor cell anticancer drug-mediated apoptosis. We identified a new HCC therapeutic target and proclaimed the potential risk of the therapeutic use of miR-122 silencing.