Isolation and Purification of Schwann Cells from Spinal Nerves of Neonatal Rat

Schwann cell‐specific RhoA knockout accelerates peripheral nerve regeneration via promoting Schwann cell dedifferentiation

Our previous studies indicated that RhoA knockdown or inhibition could alleviate the proliferation, migration, and differentiation of Schwann cells. However, the role of RhoA in Schwann cells during nerve injury and repair is still unknown. Herein, we developed two lines of Schwann cells conditional RhoA knockout (cKO) mice by breeding RhoA^{flox / flox} mice with Plp^{Cre -ERT2} or Dhh^Cre mice. Our results indicate that RhoA cKO in Schwann cells accelerates axonal regrowth and remyelination after sciatic nerve injury, which enhances the recovery of nerve conduction and hindlimb gait, and alleviates the amyotrophy in gastrocnemius muscle. Mechanistic studies in both in vivo and in vitro models revealed that RhoA cKO could facilitate Schwann cell dedifferentiation via JNK pathway. Schwann cell dedifferentiation subsequently promotes Wallerian degeneration by enhancing phagocytosis and myelinophagy, as well as stimulating the production of neurotrophins (NT-3, NGF, BDNF, and GDNF). These findings shed light on the role of RhoA in Schwann cells during nerve injury and repair, indicating that cell type-specific RhoA targeting could serve as a promising molecular therapeutic strategy for peripheral nerve injury.

Establishment of an in vitro Differentiation and Dedifferentiation System of Rat Schwann Cells

In the peripheral nervous system, Schwann cells are the primary type of glia; their in vitro differentiation and dedifferentiation system has not been described in detail in the literature. Thus, an in vitro differentiation and dedifferentiation system of rat Schwann cells is described in this protocol. These cultures and systems may be used to investigate the morphological and biochemical effects of drug interventions or lentivirus-mediated gene transfer on Schwann cells during differentiation or dedifferentiation. Graphical abstract.

Inhibition of RhoA-Subfamily GTPases Suppresses Schwann Cell Proliferation Through Regulating AKT Pathway Rather Than ROCK Pathway

Inhibiting RhoA-subfamily GTPases by C3 transferase is widely recognized as a prospective strategy to enhance axonal regeneration. When C3 transferase is administered for treating the injured peripheral nerves, Schwann cells (SCs, important glial cells in peripheral nerve) are inevitably impacted and therefore SC bioeffects on nerve regeneration might be influenced. However, the potential role of C3 transferase on SCs remains elusive. Assessed by cell counting, EdU and water-soluble tetrazolium salt-1 (WST-1) assays as well as western blotting with PCNA antibody, herein we first found that CT04 (a cell permeable C3 transferase) treatment could significantly suppress SC proliferation. Unexpectedly, using Y27632 to inhibit ROCK (the well-accepted downstream signal molecule of RhoA subfamily) did not impact SC proliferation. Further studies indicated that CT04 could inactivate AKT pathway by altering the expression levels of phosphorylated AKT (p-AKT), PI3K and PTEN, while activating AKT pathway by IGF-1 or SC79 could reverse the inhibitory effect of CT04 on SC proliferation. Based on present data, we concluded that inhibition of RhoA-subfamily GTPases could suppress SC proliferation, and this effect is independent of conventional ROCK pathway but involves inactivation of AKT pathway.

RhoA regulates Schwann cell differentiation through JNK pathway

RhoA is a small GTPase that regulates many functions of mammalian cells via actin reorganization. Lots of studies uncovered that its activation acts as a major negative regulator of neurite extension, and inhibition of RhoA activity or reduction of its expression can promote neuron survival and axonal regeneration. However, little is known about whether RhoA also exerts important functions on Schwann cells (SCs) which are the glial cells of the peripheral nervous system (PNS). Recently, we reported that RhoA plays important roles in the proliferation, migration and myelination of SCs. In the present study, using RNA interference to knockdown RhoA expression and CT04 (a cell-permeable C3 Transferase) to inhibit RhoA activation we found that blocking RhoA can slack SC differentiation. Unexpectedly, inhibiting ROCK, the mostly well-known downstream effector of RhoA, has no influence on SC differentiation. Instead, the inhibition of RhoA in differentiating SCs results in the activation of JNK and p38 MAPK. And the inhibitor of JNK but not p38 MAPK can promote SC differentiation in the presence of RhoA inhibition. Overall results indicate that RhoA plays a vital role in SC differentiation via JNK pathway rather than ROCK pathway.