KRAS mutation-induced EndMT of brain arteriovenous malformation is mediated through the TGF-β/BMP-SMAD4 pathway

Objective Somatic KRAS mutations have been identified in the majority of brain arteriovenous malformations(bAVMs),and subsequent in vivo experiments have confirmed that KRAS mutation in endothelial cells(ECs)causes AVMs in mouse and zebrafish models.Our previous study demonstrated that the KRASG12D mutant independently induced the endothelial-mesenchymal transition(EndMT),which was reversed by treatment with the lipid-lowering drug lovastatin.However,the underlying mechanisms of action were unclear.Methods We used human umbilical vein ECs(HUVECs)overexpressing the KRASG12D mutant for Western blotting,quantitative real-time PCR,and immunofluorescence and wound healing assays to evaluate the EndMT and determine the activation of downstream pathways.Knockdown of SMAD4 by RNA interference was performed to explore the role of SMAD4 in regulating the EndMT.BAVM ECs expressing the KRASG12D mutant were obtained to verify the SMAD4 function.Finally,we performed a coimmunoprecipitation assay to probe the mechanism by which lovastatin affects SMAD4.Results HUVECs infected with KRASG12D adenovirus underwent the EndMT.Transforming growth factor beta(TGF-β)and bone morphogenetic protein(BMP)signalling pathways were activated in the KRASG12D-mutant HUVECs and ECs in bAVM tissue.Knocking down SMAD4 expression in both KRASG12D-mutant HUVECs and ECs in bAVM tissues inhibited the EndMT.Lovastatin attenuated the EndMT by downregulating p-SMAD2/3,p-SMAD1/5 and acetylated SMAD4 expression in KRASG12D-mutant HUVECs.Conclusions Our findings suggest that the KRASG12D mutant induces the EndMT by activating the ERK-TGF-β/BMP-SMAD4 signalling pathway and that lovastatin inhibits the EndMT by suppressing TGF-β/BMP pathway activation and SMAD4 acetylation.

Somatic GJA4 mutation in intracranial extra-axial cavernous hemangiomas

Objective Extra-axial cavernous hemangiomas(ECHs)are sporadic and rare intracranial occupational lesions that usually occur within the cavernous sinus.The aetiology of ECHs remains unknown.Methods Whole-exome sequencing was performed on ECH lesions from 12 patients(discovery cohort)and droplet digital polymerase-chain reaction(ddPCR)was used to confirm the identified mutation in 46 additional cases(validation cohort).Laser capture microdissection(LCM)was carried out to capture and characterise subgroups of tissue cells.Mechanistic and functional investigations were carried out in human umbilical vein endothelial cells and a newly established mouse model.Results We detected somatic GJA4 mutation(c.121G>T,p.G41C)in 5/12 patients with ECH in the discovery cohort and confirmed the finding in the validation cohort(16/46).LCM followed by ddPCR revealed that the mutation was enriched in lesional endothelium.In vitro experiments in endothelial cells demonstrated that the GJA4 mutation activated SGK-1 signalling that in turn upregulated key genes involved in cell hyperproliferation and the loss of arterial specification.Compared with wild-type littermates,mice overexpressing the GJA4 mutation developed ECH-like pathological morphological characteristics(dilated venous lumen and elevated vascular density)in the retinal superficial vascular plexus at the postnatal 3 weeks,which were reversed by an SGK1 inhibitor,EMD638683.Conclusions We identified a somatic GJA4 mutation that presents in over one-third of ECH lesions and proposed that ECHs are vascular malformations due to GJA4-induced activation of the SGK1 signalling pathway in brain endothelial cells.

Brain-Computer Interfaces in Disorders of Consciousness

The development of brain-computer interfaces(BCIs)has established a new communication channel between the brain and external devices for information transmission that requires no muscular signals[1].BCIs have been preliminarily studied to improve motor functions in patients with severe motor disabilities,especially lock-in syndrome.At present,the application of BCIs has been extensively validated.

Long-term functional outcomes improved with deep brain stimulation in patients with disorders of consciousness

Background Deep brain stimulation(DBS)has been preliminarily applied to treat patients with disorders of consciousness(DoCs).The study aimed to determine whether DBS was effective for treating patients with DoC and identify factors related to patients’outcomes.Methods Data from 365 patients with DoCs who were consecutively admitted from 15 July 2011 to 31 December 2021 were retrospectively analysed.Multivariate regression and subgroup analysis were performed to adjust for potential confounders.The primary outcome was improvement in consciousness at 1 year.Results An overall improvement in consciousness at 1 year was achieved in 32.4%(12/37)of the DBS group compared with 4.3%(14/328)of the conservative group.After full adjustment,DBS significantly improved consciousness at 1 year(adjusted OR 11.90,95%CI 3.65-38.46,p<0.001).There was a significant treatment×follow up interaction(H=14.99,p<0.001).DBS had significantly better effects in patients with minimally conscious state(MCS)compared with patients with vegetative state/unresponsive wakefulness syndrome(p for interaction<0.001).A nomogram based on age,state of consciousness,pathogeny and duration of DoCs indicated excellent predictive performance(c-index=0.882).Conclusions DBS was associated with better outcomes in patients with DoC,and the effect was likely to be significantly greater in patients with MCS.DBS should be cautiously evaluated by nomogram preoperatively,and randomised controlled trials are still needed.