Heparan sulfate proteoglycans (HSPGs) are cell surface glycans that may regulate the cell fate decisions of embryonic stem cells. The absence of heparan sulfate (HS) in mice results in developmental defects, including embryonic lethality. Moreover, conditional HS knockout mouse exhibited mental impairment and defects in cognitive function. Still, the biological function of HS in the human embryonic stem (hES) cell lineage differentiation is largely unknown. To address this issue, we engineered a human embryonic stem cell line that lacks <i>EXT1</i>, an enzyme critical for heparan biosynthesis. We used this cell line lacking heparan sulfate to study the roles of this polysaccharide in neuronal differentiation. Through a comparative global gene expression analysis of the undifferentiated state using RNA-Seq, we found multiple genes related to neuronal development and physiologic synaptic activity are significantly downregulated. Moreover, the ability of these cells to differentiate into neurons is severely compromised. During motor neuron differentiation, the early neuro-ectoderm marker (Pax6), and postmitotic neuron-specific Class III β-tubulin (TuJ1) gene were significantly downregulated in the mutant cells. The neurons from this mutant cell line had an arrested axonal extension, indicating a defect in bipolar projection. Overall, our data indicate that heparin sulfate has critical roles in neurophysiological development, defects in its production are likely relevant for neurological disorders.

Critical roles of heparan sulfate in neuronal differentiation of human embryonic stem cells

256th National Meeting (2018)

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