Deficiency of N-glycanase 1 perturbs neurogenesis and cerebral development modeled by human organoids

Abstract

Mutations in N-glycanase 1 (NGLY1), which deglycosylates misfolded glycoproteins for degradation, can cause NGLY1 deficiency in patients and their abnormal fetal development in multiple organs, including microcephaly and other neurological disorders. Using cerebral organoids (COs) developed from human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), we investigate how NGLY1 dysfunction disturbs early brain development. While NGLY1 loss had limited impact on the undifferentiated cells, COs developed from NGLY1-deficient hESCs showed defective formation of SATB2-positive upper-layer neurons, and attenuation of STAT3 and HES1 signaling critical for sustaining radial glia. Bulk and single-cell transcriptomic analysis revealed premature neuronal differentiation accompanied by downregulation of secreted and transcription factors, including TTR, IGFBP2, and ID4 in NGLY1-deficient COs. NGLY1 malfunction also dysregulated ID4 and enhanced neuronal differentiation in CO transplants developed in vivo. NGLY1-deficient CO cells were more vulnerable to multiple stressors; treating the deficient cells with recombinant TTR reduced their susceptibility to stress from proteasome inactivation, likely through LRP2-mediated activation of MAPK signaling. Expressing NGLY1 led to IGFBP2 and ID4 upregulation in CO cells developed from NGLY1-deficiency patient’s hiPSCs. In addition, treatment with recombinant IGFBP2 enhanced ID4 expression, STAT3 signaling, and proliferation of NGLY1-deficient CO cells. Overall, our discoveries suggest that dysregulation of stress responses and neural precursor differentiation underlies the brain abnormalities observed in NGLY1-deficient individuals.

Genetic disruption of mammalian endoplasmic reticulum‐associated protein degradation: Human phenotypes and animal and cellular disease models

“…Genetic manipulation studies of NGLY1 in different cell types contributed to the uncovering of the association between NGLY1 and CDDG1, where NGLY1 was implicated in various cellular activities. Its deficiency showed varied responses depending on the cellular lineage and their developmental stage 241 . Moreover, to better understand the pathology of CDDG1 and its consequent neurological symptoms, patient derived midbrain organoid deficient of NGLY1 disease model was generated 242 .…”

“…Its deficiency showed varied responses depending on the cellular lineage and their developmental stage. 241 Moreover, to better understand the pathology of CDDG1 and its consequent neurological symptoms, patient derived midbrain organoid deficient of NGLY1 disease model was generated. 242 Altogether these studies show that NGLY1 regulates different biological pathways, including mitochondrial homeostasis, 243 proteasomal homeostasis, 244 as well as AMPK and BMP signaling pathways.…”