MiR-132 down-regulates high glucose-induced β-dystroglycan degradation through Matrix Metalloproteinases-9 up-regulation in primary neurons

miRNA dysregulation in Duchenne muscular dystrophy comorbidities

BACKGROUND

Duchenne muscular dystrophy (DMD) is a neuromuscular disorder caused by mutations in the dystrophin gene. DMD is reported to coexist with other comorbidities, although the occurrence of the triad, autism spectrum disorder (ASD), and epilepsy is very rare. Indeed, only one case of the triad has currently been reported. Here, we present a detailed case report of a ten-year-old boy with DMD, ASD, and epilepsy. We also investigated the dysregulation of miRNAs in this unusual triad (represented as DMD++) compared with a healthy individual and a DMD patient (represented as DMD+) without autism.

AIM

To understand the differential expression of miRNAs in rare comorbid DMD cases.

METHODS

The Sequin Form Board test, Gesell's drawing test, multiplex ligation probe amplification, and Vineland Social Maturity Scale were applied to confirm the DMD and ASD. Total RNA was isolated from samples using TRIzol. cDNA was synthesized using the Mir-X™ miRNA First-Strand Synthesis kit. qRT-PCR was performed using SYBR Advantage qPCR Premix. The results were statistically analyzed using one-way analysis of variance with Tukey's t-test.

RESULTS

miR-146a-5p and miR-132-5p showed significant downregulation in both patient samples. miR-199a-5p and miR-146a-3p showed no change in expression between the diseased and controls. miR-132-3p showed downregulation only in the DMD+ sample (0.21 ± 0.04). The decrease in miR-132-3p can result in failed silencing of the phosphatase and tensin homolog-mediated apoptotic pathway, leading to severe skeletal muscle atrophy. Here, the downregulation of miR-132-3p in DMD+ is consistent with severe muscle loss and higher disease progression than that in DMD++. DMD++ has slower disease progression, and the expression of miRNA involved in inflammatory and apoptotic responses is more similar to that of the control.

CONCLUSION

Our study shows marked difference in miRNA expression in this rare case of DMD with autism and epilepsy. These miRNAs also serve as regulators of several muscle regeneration, apoptosis, and inflammatory pathways. This study shows the significance of studying miRNAs in such rare cases in a larger cohort to progress in several intervention treatments utilizing miRNAs.

Ginkgolide B can alleviate spinal cord glymphatic system dysfunction and provide neuroprotection in painful diabetic neuropathy rats by inhibiting matrix metalloproteinase-9

The glymphatic system plays a crucial role in maintaining optimal central nervous system (CNS) function by facilitating the removal of metabolic wastes. Aquaporin-4 (AQP4) protein, predominantly located on astrocyte end-feet, is a key pathway for metabolic waste excretion. β-Dystroglycan (β-DG) can anchor AQP4 protein to the end-feet membrane of astrocytes and can be cleaved by matrix metalloproteinase (MMP)-9 protein. Studies have demonstrated that hyperglycemia upregulates MMP-9 expression in the nervous system, leading to neuropathic pain. Ginkgolide B (GB) exerts an inhibitory effect on the MMP-9 protein. In this study, we investigated whether inhibition of MMP-9-mediated β-DG cleavage by GB is involved in the regulation of AQP4 polarity within the glymphatic system in painful diabetic neuropathy (PDN) and exerts neuroprotective effects. The PDN model was established by injecting streptozotocin (STZ). Functional changes in the glymphatic system were observed using magnetic resonance imaging (MRI). The paw withdrawal threshold (PWT) was measured to assess mechanical allodynia. The protein expressions of MMP-9, β-DG, and AQP4 were detected by Western blotting and immunofluorescence. Our findings revealed significant decreases in the efficiency of contrast agent clearance within the spinal glymphatic system of the rats, accompanied by decreased PWT, increased MMP-9 protein expression, decreased β-DG protein expression, and loss of AQP4 polarity. Notably, GB treatment demonstrated the capacity to ameliorate spinal cord glymphatic function by modulating AQP4 polarity through MMP-9 inhibition, offering a promising therapeutic avenue for PDN.

Presequence protease reverses mitochondria-specific amyloid-β-induced mitophagy to protect mitochondria

Amyloid-β (Aβ) peptide is accumulated in the mitochondria and has been shown to play a central role in the development of Alzheimer's disease (AD). It has been shown that exposure of neurons to aggregated Aβ can result in damaged mitochondria and dysregulated mitophagy, indicating that changes in the Aβ content of mitochondria may affect the levels of mitophagy and interfere with the progression of AD. However, the direct influence of mitochondrial Aβ on mitophagy has not been elucidated. In the present study, the effect of the mitochondria-specific Aβ was assessed following a direct change of Aβ content in the mitochondria. We directly change mitochondrial Aβ by transfecting cells with mitochondria-associated plasmids, including the mitochondrial outer membrane protein translocase 22 (TOMM22) and 40 (TOMM40) or presequence protease (PreP) overexpression plasmids. The changes in the levels of mitophagy were assessed by TEM, Western blot, mito-Keima construct, organelle tracker, and probe JC-1 assay. We demonstrated that increased mitochondrial Aβ content enhance mitophagy levels; overexpression of PreP could reverse the mitochondrial Aβ-induced mitophagy levels in vivo and in vitro by reversing the levels of reactive oxygen species (ROS) and the mitochondrial membrane potential. The data provide novel insight into the role of mitochondria-specific Aβ in the progression of AD pathophysiology.

Brain Imaging Changes and Related Risk Factors of Cognitive Impairment in Patients With Heart Failure

Background/Aims

To explore the imaging changes and related risk factors of heart failure (HF) patients with cognitive impairment (CI).

Methods

A literature search was systematically carried out in PubMed, Web of Science, Embase, and Cochrane Library. In this systematic review, important relevant information was extracted according to the inclusion and exclusion criteria. The methodological quality was assessed by three scales according to the different study types.

Results

Finally, 66 studies were included, involving 33,579 patients. In the imaging changes, the severity of medial temporal lobe atrophy (MTA) and the decrease of gray Matter (GM) volume were closely related to the cognitive decline. The reduction of cerebral blood flow (CBF) may be correlated with CI. However, the change of white matter (WM) volume was possibly independent of CI in HF patients. Specific risk factors were analyzed, and the data indicated that the increased levels of B-type natriuretic peptide (BNP)/N-terminal pro-B-type natriuretic peptide (NT-proBNP), and the comorbidities of HF, including atrial fibrillation (AF), diabetes mellitus (DM) and anemia were definitely correlated with CI in patients with HF, respectively. Certain studies had also obtained independent correlation results. Body mass index (BMI), depression and sleep disorder exhibited a tendency to be associated with CI. Low ejection fraction (EF) value (<30%) was inclined to be associated with the decline in cognitive function. However, no significant differences were noted between heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF) in cognitive scores.

Conclusion

BNP/NT-proBNP and the comorbidities of HF including AF, DM and anemia were inextricably correlated with CI in patients with HF, respectively. These parameters were independent factors. The severity of MTA, GM volume, BMI index, depression, sleep disorder, and low EF value (<30%) have a disposition to associated with CI. The reduction in the CBF volume may be related to CI, whereas the WM volume may not be associated with CI in HF patients. The present systematic review provides an important basis for the prevention and treatment of CI following HF.

MiR-132 down-regulates high glucose-induced β-dystroglycan degradation through Matrix Metalloproteinases-9 up-regulation in primary neurons

Cognitive dysfunction is one of the complications of diabetes. Unfortunately, there is no effective methods to block its progression currently. One of the pathophysiological mechanisms is synaptic protein damage and neuronal signal disruption because of glucose metabolism disorder. Dystroglycan protein, located in the post‐synaptic membrane of neurons, links the intracellular cytoskeleton with extracellular matrix. Abnormal expression of dystroglycan protein affects neuronal biological functions and leads to cognitive impairment. However, there are no relevant studies to observe the changes of β‐dystroglycan protein in diabetes rat brain and in primary neurons under high glucose exposure. Our data demonstrated the alterations of cognitive abilities in the diabetic rats; β‐dystroglycan protein degradation occurred in hippocampal and cortical tissues in diabetic rat brain. We further explored the mechanisms underlying of this phenomenon. When neurons are exposed to high glucose environment in long‐term period, microRNA‐132 (miR‐132) would be down‐regulated in neurons. Matrix Metalloproteinases‐9 (MMP‐9) mRNA, as a target of miR‐132, could be up‐regulated; higher expression and overlay activity of MMP‐9 protein could increase β‐DG protein degradation. In this way, β‐DG degradation may affect structure and functions among the synapses, which related to cognition decline. It may provide some theoretical basis for elucidating the molecular mechanism of diabetes‐induced cognitive dysfunction.