Sustained ErbB activation causes demyelination and hypomyelination by driving necroptosis of mature oligodendrocytes and apoptosis of oligodendrocyte precursor cells

Abstract

Oligodendrocytes are vulnerable to genetic and environmental insults and its injury leads to demyelinating diseases. The roles of ErbB receptors in the CNS myelin integrity are largely unknown. Here we overactivate ErbB receptors that mediate signaling of either neuregulin or EGF family growth factors and found their synergistic activation caused deleterious outcomes in white matter. Sustained ErbB activation induced by the tetracycline-dependent mouse tool Plp-tTA resulted in demyelination, axonal degeneration, oligodendrocyte precursor cell (OPC) proliferation, astrogliosis, and microgliosis in white matter. Moreover, there was hypermyelination prior to these pathological events. In contrast, sustained ErbB activation induced by another tetracycline-dependent mouse tool Sox10+/rtTA caused hypomyelination in the corpus callosum and optic nerve, which appeared to be a developmental deficit and did not associate with OPC regeneration, astrogliosis, or microgliosis. By analyzing the differentiation states of cells that were pulse- labeled with a viral reporter, we found that, during juvenile to adolescent development, Plp-tTA targeted mainly mature oligodendrocytes (MOs), while Sox10+/rtTA targeted OPCs and newly-formed oligodendrocytes. The distinct phenotypes of mice with ErbB overactivation induced by Plp-tTA and Sox10+/rtTA supported the reporter pulse-labeling results, and consolidated their non-overlapping targeting preferences in the oligodendrocyte lineage after early development. These features enabled us to demonstrate that ErbB overactivation in MOs induced necroptosis that caused pathological demyelination, whereas in OPCs induced apoptosis that caused developmental hypomyelination. These results established an upstream pathogenic role of ErbB overactivation in oligodendrocytes, providing molecular and cellular insights into the primary oligodendropathy in demyelinating diseases.

ErbB inhibition impairs cognition via disrupting myelination and aerobic glycolysis in oligodendrocytes

“…For indicated behavioral tests, only male mice were used, while both male and female mice were used for the rest behavioral tests because the results were not affected by sex difference. Tet-Off or Tet-On treatments were performed as previously reported 41 .…”

“…Samples were processed and ultrathin sections were obtained and stained with 2% uranyl acetate. EM images were captured with Tecnai 10 (FEI) and analyzed as previously reported 41, 44 .…”

“…Brain slices or coverslips were obtained and stained as previously described 41, 45 . The primary antibodies used were: CC1 (1:500, Abcam, ab16794), NG2 (1:200, Abcam, ab50009), Ki67 (1:400, Cell Signaling Technology, 9129), TCF4 (1:500, Millipore, 05-511), Olig2 (1:500, Millipore, AB9610), MBP (1:100, Millipore, MAB382), ASPA (1:500, Oasis, OB-PRT005), PDGFRα (1:500, Oasis, OB-PRB011), Olig2 (1:3000, Oasis, OB-PGP040), MBP (1:2000, Abcam, ab7349).…”

“…Subcortical white matter tissues were isolated and homogenized. Proteins were extracted and processed as previously reported 41 . The primary antibodies used were: pErbB3 (1:2500, Abcam, ab133459), pErbB4 (1:2500, Abcam, ab109273), pErbB2 (1:2500, Abgent, AP3781q), EGFR (1:5000, Epitomics, 1902-1), pEGFR (1:2500, Epitomics, 1727-1), GAPDH (1:5000, Huabio, EM1101), MBP (1:1000, Millipore, MAB382), Olig2 (1:1000, Millipore, MABN50), Olig2 (1:1000, Huabio, ET1604-29), ErbB3 (1:200, Santa Cruz Biotechnology, sc-285), ErbB4 (1:200, Santa Cruz Biotechnology, sc-283), ErbB2 (1:200, Santa Cruz Biotechnology, sc-284), LDHA (1:2000, Abclonal, A1146), PKm2 (1:2000, Abclonal, A13905), GluT1 (1:2000, Abclonal, A6982), MCT2 (1:2000, Abclonal, A12386), MCT1 (1:2000, Abclonal, A3013), LDHB (1:2000, Abclonal, A18096).…”

“…To study the oligodendroglial functions of ErbB signaling, we adopted an inducible pan-ErbB strategy that blocked the activities of any endogenous ErbB receptors in OL-lineage cells in vivo . By using two valuable research mouse tools that help distinguish the outcomes induced by defects of OLs at different differentiation stages, Sox10 +/rtTA (Tet-on) that target OPC-NFOs and Plp -tTA (Tet-off) that target MOs 41 , we were able to demonstrate that disruption of ErbB signaling causes myelination-dependent and -independent white matter abnormalities, and prove that both pathophysiological changes lead to cognitive deficits.…”