Downregulation MIWI-piRNA regulates the migration of Schwann cells in peripheral nerve injury

Although MIWI (PIWI in humans) regulates spermatogenesis and translation machinery, its role in peripheral nerve injury is poorly understood. In this study, we characterized the expression profiles of MIWI after sciatic nerve injury. The results revealed that MIWI was downregulated after sciatic nerve injury. MIWI was colocalized with S100 (a Schwan cell marker), and TOM20 (a mitochondrial marker) on uncut nerves, while some MIWI was also colocalized with myelin protein zero (a myelin marker) on injured nerves. Immunofluorescence revealed that some MIWI was colocalized with SOX10 in the nuclear compartment following nerve injury. MIWI depletion by MIWI siRNA resulted in the reduction of EGR2. To characterize the expression of PIWI interacting RNA (piRNA) during sciatic nerve injury, microarray-based piRNA was conducted. The results revealed that 3447 piRNAs were upregulated, while 4117 piRNAs were downregulated after nerve transection. Interestingly, piR 009614 downregulated the mRNA level of MBP and enhanced the migration of RT-4 Schwann cells. Together, our results suggest that the MIWI-piRNA complex may play a role in Schwann cell responses to nerve injury.