Transcriptional Alteration in TRKβ-SHC Isoform as a Neuroprotective Factor for Post-Stroke Memory Outcomes

Abstract

Post-stroke cognitive impairment (PSCI) affects nearly 30% of stroke survivors and substantially limits functional recovery. Brain-derived neurotrophic factor (BDNF)–tropomyosin receptor kinase-β (Trkβ) signalling plays an important role in synaptic plasticity and cognitive function; however, the contribution of individual NTRK2/Trkβ isoforms to PSCI remains poorly understood. This study investigated (a) isoform-specific NTRK2 mRNA expression, (b) genetic association of the isoform-specific variant rs6559833 with post-stroke cognitive outcomes and (c) DNA methylation patterns potentially regulating NTRK2 expression using blood as primary biosource. Isoform-specific expression was analysed in 50 subjects, rs6559833 was genotyped in 280 ischemic stroke patients, and DNA methylation was assessed in 10 samples using whole-genome bisulfite sequencing. The TRKβ-FL expression was significantly reduced in stroke patients compared with healthy controls, whereas TRKβ-SHC expression was higher in PSCN individuals than in PSCI patients. The latter showed positive correlation with MEK2 expression and memory performance. The ‘TT’ genotype of the rs6559833 variant showed marginal associations with post-stroke memory status and overall BMSE scores (p = 0.0442 and 0.0488, respectively). Furthermore, hypermethylation was observed within the NTRK2 gene body and in genes encoding its splicing regulators, whereas no evident difference in promoter methylation was observed. Collectively, these findings suggest that Trkβ-SHC expression may be associated with preserved cognitive function after stroke and indicate a potential relationship between isoform-specific NTRK2 expression, genetic regulation and cognitive outcomes in PSCI.