The Neuroanatomical Basis of the 5-HT Syndrome and Harmalineinduced Tremor

The 5-HT syndrome in rats is composed of head weaving, body shaking, forepaw treading, flat body posture, hindlimb abduction, and Straub tail. The importance of the brainstem and spinal cord for the syndrome is underlined by findings of 5,7-dihydroxytryptamine (5,7-DHT)-induced denervation supersensitivity in response to 5-HT-stimulant drugs. For head weaving and Straub tail, supersensitivity occurred when the neurotoxin was injected into the cisterna magna or spinal cord, for forepaw treading in cisterna magna, and for hindlimb abduction in the spinal cord. Although 5,7- DHT-related body shaking increased in the spinal cord, the sign decreased when injected into the striatum, indicating the modulatory influence of the basal ganglia. Further details on body shaking are provided by its reduced response to harmaline after 5-HT depletion caused by intraventricular 5,7-DHT, electrolytic lesions of the medial or dorsal raphe, and lesions of the inferior olive caused by systemic injection of 3-acetylpyridine along with those found in Agtpbp1pcd or nr cerebellar mouse mutants. Yet the influence of the climbing fiber pathway on other signs of the 5-HT syndrome remains to be determined.

Regulator of G protein signaling protein 6 alleviates acute lung injury by inhibiting inflammation and promoting cell self-renewal in mice

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a disease with high mortality and morbidity. Regulator of G protein signaling protein 6 (RGS6), identified as a tumor suppressor gene, has received increasing attention owing to its close relationship with oxidative stress and inflammation. However, the association between ARDS and RGS6 has not been reported.

METHODS

Congruously regulated G protein-coupled receptor (GPCR)-related genes and differentially expressed genes (DEGs) in an acute lung injury (ALI) model were identified, and functional enrichment analysis was conducted. In an in vivo study, the effects of RGS6 knockout were studied in a mouse model of ALI induced by lipopolysaccharide (LPS). HE staining, ELISA, and immunohistochemistry were used to evaluate pathological changes and the degree of inflammation. In vitro, qRT‒PCR, immunofluorescence staining, and western blotting were used to determine the dynamic changes in RGS6 expression in cells. The RGS6 overexpression plasmid was constructed for transfection. qRT‒PCR was used to assess proinflammatory factors transcription. Western blotting and flow cytometry were used to evaluate apoptosis and reactive oxygen species (ROS) production. Organoid culture was used to assess the stemness and self-renewal capacity of alveolar epithelial type II cells (AEC2s).

RESULTS

A total of 110 congruously regulated genes (61 congruously upregulated and 49 congruously downregulated genes) were identified among GPCR-related genes and DEGs in the ALI model. RGS6 was downregulated in vivo and in vitro in the ALI model. RGS6 was expressed in the cytoplasm and accumulated in the nucleus after LPS stimulation. Compared with the control group, we found higher mortality, more pronounced body weight changes, more serious pulmonary edema and pathological damage, and more neutrophil infiltration in the RGS6 knockout group upon LPS stimulation in vivo. Moreover, AEC2s loss was significantly increased upon RGS6 knockout. Organoid culture assays showed slower alveolar organoid formation, fewer alveolar organoids, and impaired development of new structures after passaging upon RGS6 knockout. In addition, RGS6 overexpression decreased ROS production as well as proinflammatory factor transcription in macrophages and decreased apoptosis in epithelial cells.

CONCLUSIONS

RGS6 plays a protective role in ALI not only in early inflammatory responses but also in endogenous lung stem cell regeneration.

Transglutaminase 2: an enigmatic enzyme with diverse functions

Transglutaminase 2 (TG2) is an inducible transamidating acyltransferase that catalyzes Ca(2+)-dependent protein modifications. It acts as a G protein in transmembrane signalling and as a cell surface adhesion mediator, this distinguishes it from other members of the transglutaminase family. The sequence motifs and domains revealed in the recent TG2 structure, can each be assigned distinct cellular functions, including the regulation of cytoskeleton, cell adhesion and cell death. Ablation of TG2 in mice results in impaired wound healing, autoimmunity and diabetes, reflecting the number and variety of TG2 functions. An important role for the enzyme in the pathogenesis of coeliac disease, fibrosis and neurodegenerative disorders has also been demonstrated, making TG2 an important therapeutic target.