Heat shock protein A12A (HSPA12A) is a newly discovered member of the Hsp70 family. The biological characteristics and functional roles of HSPA12A are poorly understood. This study investigated the effects of HSPA12A on ischaemic stroke in mice. Ischaemic stroke was induced by left middle cerebral artery occlusion for 1 h followed by blood reperfusion. We observed that HSPA12A was highly expressed in brain neurons, and neuronal HSPA12A expression was downregulated by ischaemic stroke and stroke-associated risk factors (aging, obesity and hyperglycaemia). To investigate the functional requirement of HSPA12A in protecting ischaemic brain injury, HSPA12A knockout mice (Hspa12a−/−) were generated. Hspa12a−/− mice exhibited an enlarged infarct volume and aggravated neurological deficits compared to their wild-type (WT) littermates after stroke. These aggravations in Hspa12a−/− mice were accompanied by more apoptosis and severer hippocampal morphological abnormalities in ischaemic hemispheres. Long-term examination revealed impaired motor function recovery and neurogenesis in stroke-affected Hspa12a−/− mice compared to stroke-affected WT controls. Significant reduced activation of GSK-3β/mTOR/p70S6K signalling was also observed in ischaemic hemispheres of Hspa12a−/− mice compared to WT controls. Administration with lithium (non-selective GSK-3β inhibitor) activated GSK-3β/mTOR/p70S6K signalling in stroke-affected Hspa12a−/− mice. Notably, lithium administration attenuated the HSPA12A deficiency-induced aggravation in infarct size, neurological deficits and neuronal death in Hspa12a−/− mice after stroke. Altogether, the findings suggest that HSPA12A expression encodes a critical novel prosurvival pathway during ischaemic stroke. We identified HSPA12A as a novel neuroprotective target for stroke patients.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions. Background: Metastasis accounts for 90% of cancer-associated mortality in patients with renal cell carcinoma (RCC). However, the clinical management of RCC metastasis is challenging. Lactate export is known to play an important role in cancer cell migration. This study investigated the role of heat shock protein A12A (HSPA12A) in RCC migration. Methods: HSPA12A expression was examined in 82 pairs of matched RCC tumors and corresponding normal kidney tissues from patients by immunoblotting and immunofluorescence analyses. The proliferation of RCC cells was analyzed using MTT and EdU incorporation assays. The migration of RCC cells was evaluated by wound healing and Transwell migration assays. Extracellular acidification was examined using Seahorse technology. Protein stability was determined following treatment with protein synthesis inhibitor cycloheximide and proteasome inhibitor MG132. Mass spectrometry, immunoprecipitation, and immunoblotting were employed to examine protein-protein interactions. Results: RCC tumors from patients showed downregulation of HSPA12A, which was associated with advanced tumor node metastasis stage. Intriguingly, overexpression of HSPA12A in RCC cells inhibited migration, whereas HSPA12A knockdown had the opposite effect. Lactate export, glycolysis rate, and CD147 protein abundance were also inhibited by HSPA12A overexpression but promoted by HSPA12A knockdown. An interaction of HSPA12A with HRD1 ubiquitin E3 ligase was detected in RCC cells. Further studies demonstrated that CD147 ubiquitination and proteasomal degradation were promoted by HSPA12A overexpression whereas inhibited by HSPA12A knockdown. Notably, the HSPA12A overexpression-induced inhibition of lactate export and migration were abolished by CD147 overexpression. Conclusion: Human RCC shows downregulation of HSPA12A. Overexpression of HSPA12A in RCC cells unstabilizes CD147 through increasing its ubiquitin-proteasome degradation, thereby inhibits lactate export and glycolysis, and ultimately suppresses RCC cell migration. Our results demonstrate that overexpression of HSPA12A might represent a viable strategy for managing RCC metastasis.