ABSTRACT
Ependymal cells reside in the adult spinal cord and display stem cell properties in vitro. They proliferate after spinal cord injury and produce neurons in lower vertebrates but predominantly astrocytes in mammals. The mechanisms underlying this glial-biased differentiation remain ill-defined. We addressed this issue by generating a molecular resource through RNA profiling of ependymal cells before and after injury. We found that these cells activate STAT3 and ERK/MAPK signaling post injury and downregulate cilia-associated genes and FOXJ1, a central transcription factor in ciliogenesis. Conversely, they upregulate 510 genes, seven of them more than 20-fold, namely Crym, Ecm1, Ifi202b, Nupr1, Rbp1, Thbs2 and Osmr-the receptor for oncostatin, a microglia-specific cytokine which too is strongly upregulated after injury. We studied the regulation and role of Osmr using neurospheres derived from the adult spinal cord. We found that oncostatin induced strong Osmr and p-STAT3 expression in these cells which is associated with reduction of proliferation and promotion of astrocytic versus oligodendrocytic differentiation. Microglial cells are apposed to ependymal cells in vivo and co-culture experiments showed that these cells upregulate Osmr in neurosphere cultures. Collectively, these results support the notion that microglial cells and Osmr/Oncostatin pathway may regulate the astrocytic fate of ependymal cells in spinal cord injury.
Subject(s)
Cell Lineage , Ependyma/metabolism , Gene Expression Profiling , Gene Expression Regulation , Oncostatin M/metabolism , RNA/genetics , Spinal Cord Injuries/genetics , Stem Cells/pathology , Animals , Cell Differentiation/genetics , Cell Proliferation/genetics , Cilia/genetics , Down-Regulation/genetics , Intercellular Signaling Peptides and Proteins/metabolism , Mice , Mice, Inbred C57BL , Microglia/metabolism , Oncostatin M Receptor beta Subunit , RNA/metabolism , Spheroids, Cellular/metabolism , Spinal Cord/pathology , Up-Regulation/geneticsABSTRACT
Spinal cord injury (SCI) induces permanent loss of sensitive and motor functions below the injury level. To date, a wide variety of cells has been used as biotherapies to cure SCI in different animal paradigms. Specifically, olfactory ensheathing cells (OECs) is one of the most promising. Indeed, OECs have been shown to enhance recovery in many animal studies. Moreover, OECs transplantation has been applied to a paraplegic patient and have shown beneficial effects. However, it has been reported that the significant level of recovery varies among different patients. Therefore, it is of primary importance to enhance the regenerative efficiency of OECs for better translations. Recently, it has been shown that inhibiting ADAMTS4 expression in glial cells in vitro increases their synthesis of neurotrophic factors. We hypothesized that the expression of neurotrophic factors secreted by OECs can be increased by the deletion of ADAMTS4. Taking advantage of ADAMTS4-/- mouse line, we produce ADAMTS4 deficient primary OEC cultures and then we investigated their regenerative potential after SCI. By using quantitative polymerase chain reaction, bioluminescence imaging, measurement of locomotor activity, electrophysiological studies, and immunohistochemistry, our results show that ADAMTS4-/- olfactory bulb OEC (bOECs) primary cultures upregulate their trophic factor expression in vitro, and that the transplantation of ADAMTS4-/- bOECs in a severe SCI model increases functional recovery and tissue repair in vivo. Altogether, our study reveals, for the first time, that primary bOEC cultures transplantation can be potentialized by inhibition of the expression of ADAMTS4.
Subject(s)
ADAMTS4 Protein/antagonists & inhibitors , Olfactory Bulb/metabolism , Olfactory Bulb/transplantation , Recovery of Function/physiology , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/therapy , ADAMTS4 Protein/biosynthesis , ADAMTS4 Protein/deficiency , ADAMTS4 Protein/genetics , Animals , Cell Transplantation/methods , Cell Transplantation/trends , Cells, Cultured , Gene Expression , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Nerve Regeneration/physiology , Olfactory Bulb/cytologyABSTRACT
Development of the spinal cord requires dynamic and tightly controlled expression of numerous transcription factors. Forkhead Box protein J1 (FoxJ1) is a transcription factor involved in ciliogenesis and is specifically expressed in ependymal cells (ECs) in the adult central nervous system. However, using FoxJ1 fate-mapping mouse lines, we observed that FoxJ1 is also transiently expressed by the progenitors of other neural subtypes during development. Moreover, using a knock-in mouse line, we discovered that FoxJ1 is essential for embryonic progenitors to follow a normal developmental trajectory. FoxJ1 loss perturbed embryonic progenitor proliferation and cell fate determination, and resulted in formation of adult ECs having impaired stem cell potential and an inability to respond to spinal cord injury in both male and female animals. Thus, our study uncovers unexpected developmental functions of FoxJ1 in cell fate determination of subsets of neural cells and suggests that FoxJ1 is critical for maintaining the stem cell potential of ECs into adulthood.
