β-1, 3-galactosyltransferase 2 ameliorates focal ischemic cerebral injury by maintaining blood-brain barrier integrity

The positive role of transforming growth factor-β1 in ischemic stroke

Ischemic stroke is one of the most disabling and fatal diseases around the world. The damaged brain tissues will undergo excessive autophagy, vascular endothelial cells injury, blood-brain barrier (BBB) impairment and neuroinflammation after ischemic stroke. However, there is no unified viewpoint on the underlying mechanism of brain damage. Transforming growth factor-β1 (TGF-β1), as a multi-functional cytokine, plays a crucial role in the intricate pathological processes and helps maintain the physiological homeostasis of brain tissues through various signaling pathways after ischemic stroke. In this review, we summarize the protective role of TGF-β1 in autophagic flux, BBB, vascular remodeling, neuroinflammation and other aspects after ischemic stroke. Based on the review, we believe that TGF-β1 could serve as a key target for treating ischemic stroke.

β-1,4-Galactosyltransferase 1 protects against cerebral ischemia injury in mice by suppressing ferroptosis via the TAZ/Nrf2/HO-1 signaling pathway

BACKGROUND

Ischemic stroke leads a primary cause of mortality in human diseases, with a high disability rate worldwide. This study aims to investigate the function of β-1,4-galactosyltransferase 1 (B4galt1) in mouse brain ischemia/reperfusion (I/R) injury.

METHODS

Recombinant human B4galt1 (rh-B4galt1) was intranasally administered to the mice model of middle cerebral artery occlusion (MCAO)/reperfusion. In this study, the impact of rh-B4galt1 on cerebral injury assessed using multiple methods, including the neurological disability status scale, 2,3,5-triphenyltetrazolium chloride (TTC), Nissl and TUNEL staining. This study utilized laser speckle Doppler flowmeter to monitor the cerebral blood flow. Western blotting was performed to assess the protein expression levels, and fluorescence-labeled dihydroethidium method was performed to determine the superoxide anion generation. Assay kits were used for the measurement of iron, malondialdehyde (MDA) and glutathione (GSH) levels.

RESULTS

We demonstrated that rh-B4galt1 markedly improved neurological function, reduced cerebral infarct volume and preserved the completeness of blood-brain barrier (BBB) for preventing damage. These findings further illustrated that rh-B4galt1 alleviated oxidative stress, lipid peroxidation, as well as iron deposition induced by I/R. The vital role of ferroptosis was proved in brain injury. Furthermore, the rh-B4galt1 could increase the levels of TAZ, Nrf2 and HO-1 after I/R. And TAZ-siRNA and ML385 reversed the neuroprotective effects of rh-B4galt1.

CONCLUSIONS

The results indicated that rh-B4galt1 implements neuroprotective effects by modulating ferroptosis, primarily via upregulating TAZ/Nrf2/HO-1 pathway. Thus, B4galt1 could be seen as a promising novel objective for ischemic stroke therapy.

Exosomal miR-370-3p increases the permeability of blood-brain barrier in ischemia/reperfusion stroke of brain by targeting MPK1

Ischemia/reperfusion (I/R) damage induced by stroke poses a serious hazard to human life, while mechanism of blood-brain barrier (BBB) dysfunction is still unknown. To imitate stroke induced ischemia conditions in vivo, the rat model of cerebral I/R damage was created by middle cerebral artery occlusion (MCAO). In vitro, the rat microvascular endothelial cell line bEND.3 was subjected to oxygen-glucose deprivation/reperfusion (OGD/R). Evans blue was used to evaluate the permeability of the blood-brain barrier (BBB). To evaluate gene expression at the mRNA and protein levels, researchers used real-time PCR and western blotting. Infarct volume and BBB permeability were considerably higher in cerebral (I/R) animals than in the Sham group. Exosomal miR-370-3p expression was shown to be higher in the brains of I/R injured rats and OGD/R treatment bEND.3. The BBB permeability was considerably increased when miR-370-3p was downregulated in OGD/R pretreated bEND.3. miR-370-3p regulates MAPK1 expression by targeting it. In bEND.3, OGD/R therapy increased BBB permeability substantially. OGD/R was inhibited by miR-370-3p mimic transfection, while miR-370-3p mimic was abolished by co-transfection with MAPK1 overexpression lentivirus. In cerebral I/R damage, exosomal miR-370-3p targets MAPK1 and aggregates BBB permeability.

Salidroside Alleviates Diabetic Cognitive Dysfunction Via B3galt2/F3/Contactin Signaling Pathway in Mice

Diabetes is frequently accompanied by cognitive impairment with insidious onset, and progressive cognitive and behavioral changes. β-1, 3-galactosyltransferase 2 (B3galt2) contributes to glycosylation, showing a clue for neuronal apoptosis, proliferation and differentiation. However, the role of B3galt2 in diabetic cognitive dysfunction (DCD) has not been investigated. In the present study, we aimed to explore the role of B3galt2 in DCD. Additionally, the potential therapeutic effects of salidroside on DCD was also explored. Diabetic C57BL/6J mice showed cognitive dysfunction together with down-regulated B3galt2. Overexpression of B3galt2 reversed the cognitive decline of diabetic C57BL/6J. Moreover, cognitive impairment was aggravated in B3galt2^+/- diabetic mice compared with C57BL/6J diabetic mice. Immunohistochemistry fluorescence indicated that B3galt2 and F3/Contactin were co-localized in the hippocampal regions. Importantly, the expression of F3/Contactin can be regulated by the manipulation of B3galt2, overexpression of which assuaged hippocampal neuronal damage, protected the synapsin, and reduced neuronal apoptosis in diabetic mice. Interestingly, SAL alleviated DCD and reversed the expression of B3galt2 in diabetic C57BL/6J mice. These findings indicate that inhibition of B3galt2/F3/Contactin pathway contributes to DCD, and participates in SAL reversed DCD.

Effects of the genetic knockout of the β-1,3-galactosyltransferase 2 on spatial learning and neurons in the adult mouse hippocampus and somatosensory cortex

OBJECTIVE

Glycosyltransferases contribute to the biosynthesis of glycoproteins, proteoglycans and glycolipids and play essential roles in various processes in the brain, such as learning and memory, brain development, neuronal survival and neurodegeneration. β-1,3-galactosyltransferase 2 (B3galt2) belongs to the β-1,3-galactosyltransferase gene family and is highly expressed in the brain. Recent studies have indicated that B3galt2 plays a vital role in ischemic stroke through several signaling pathways in a mouse model. However, the function of B3galt2 in the brain remains poorly understood.

METHODS

The genotypes of mice were determined by PCR. To verify B3galt2 expression in an adult mouse brain, X-gal staining was performed in 6-month-old B3galt2 heterozygous (B3galt2+/-) mice. Using adult B3galt2 homozygous (B3galt2-/-), heterozygous and wild-type (WT) littermates, spatial learning and memory were determined by the Morris Water Maze test, and neurotoxicity and synaptic plasticity were examined by immunofluorescence.

RESULTS

B3galt2 was highly expressed in the adult mouse hippocampus and cortex, especially in the hippocampal dentate gyrus. Compared to that of WT mice, the spatial learning ability of adult B3galt2-/- mice was impaired. B3galt2 mutations also caused neuronal loss and synaptic dysfunction in the hippocampus and somatosensory cortex, and these changes were more obvious in B3galt2-/- mice than in B3galt2+/- mice.

CONCLUSIONS

The findings indicate that B3galt2 plays an important role in cognitive function, neuronal maintenance and synaptic plasticity in the adult mouse brain. This study suggests that genetic and/or pharmacological manipulation of glycosyltransferases may be a novel strategy for elucidating the mechanism of and managing various brain disorders.