Electroacupuncture Promotes Nerve Regeneration and Functional Recovery Through Regulating lncRNA GAS5 Targeting miR-21 After Sciatic Nerve Injury.

Although the benefits of electroacupuncture (EA) for peripheral nerve injury (PNI) are well accepted in clinical practice, the underlying mechanism remains incompletely elucidated. In our study, we observed that EA intervention led to a reduction in the expression of the long non-coding RNA growth-arrest-specific transcript 5 (GAS5) and an increased in miR-21 levels within the injured nerve, effectively promoting functional recovery and nerve regeneration following sciatic nerve injury (SNI). In contrast, administration of adeno-associated virus expressing GAS5 (AAV-GAS5) weakened the therapeutic effect of EA. On the other hand, both silencing GAS5 and introducing a miR-21 mimic prominently enhanced the proliferation activity and migration ability of Schwann cells (SCs), while also inhibiting SCs apoptosis. On the contrary, inhibition of SCs apoptosis was found to be mediated by miR-21. Additionally, overexpression of GAS5 counteracted the effects of the miR-21 mimic on SCs. Moreover, SCs that transfected with the miR-21 mimic promoted neurite growth in hypoxia/reoxygenation-induced neurons, which might be prevented by overexpressing GAS5. Furthermore, GAS5 was found to be widely distributed in the cytoplasm and was negatively regulated by miR-21. Consequently, the targeting of GAS5 by miR-21 represents a potential mechanism through which EA enhances reinnervation and functional restoration following SNI. Mechanistically, the GAS5/miR-21 axis can modulate the proliferation, migration, and apoptosis of SCs while potentially influencing the neurite growth of neurons.

Schwann cells-derived exosomal miR-21 participates in high glucose regulation of neurite outgrowth.

As a common complication of diabetes, the pathogenesis of diabetic peripheral neuropathy (DPN) is closely related to high glucose but has not been clarified. Exosomes can mediate crosstalk between Schwann cells (SC) and neurons in the peripheral nerve. Herein, we found that miR-21 in serum exosomes from DPN rats was decreased. SC proliferation was inhibited, cell apoptosis was increased, and the expression of miR-21 in cells and exosomes was downregulated when cultured in high glucose. Increasing miR-21 expression reversed these changes, while knockdown of miR-21 led to the opposite results. When co-cultured with exosomes derived from SC exposed to high glucose, neurite outgrowth was inhibited. On the contrary, neurite outgrowth was accelerated when incubated with exosomes rich in miR-21. We further demonstrated that the SC-derived exosomal miR-21 participates in neurite outgrowth probably through the AKT signaling pathway. Thus, SC-derived exosomal miR-21 contributes to high glucose regulation of neurite outgrowth.

Formation of an intramolecular G-quadruplex of human telomere induced by poly(L-lysine) under salt-deficient conditions.

A single-stranded G-tract human telomere DNA sequence is able to fold into intramolecular G-quadruplex structures which may be important for a number of biological processes and disease-related mechanisms. Poly(L-lysine) (PLL) polymer is linear polypeptides with lysine as the repeat unit and has been employed as a gene carrier in achieving targeted delivery of DNA to cancer cells. To explore the influence of PLL on the conformation of Hum24 DNA, we have investigated the interaction of PLL with Hum24 by biophysical methods, mainly CD, ESI-MS, and polyacrylamide gel electrophoresis for the first time. The CD data have shown that PLL can induce single-stranded Hum24 to form an intramolecular parallel G-quadruplex structure, further confirmed by ESI-MS analysis and gel electrophoresis results. The formation of an intramolecular G-quadruplex is strongly dependent on the Hum24/PLL molar ratios and the length of both the polypeptides and oligonucleotide. Such phenomena may be interpreted by electrostatically attracting negative-charged Hum24 by positive-charged PLL which facilitates the close contact between the guanines and formation of hydrogen bonding, thus leading the final shape of a G-quadruplex structure.