Deficiency in the omega-3 lysolipid transporter Mfsd2a leads to aberrant oligodendrocyte lineage development and
Vetrivel Sengottuvel1, Monalisa Hota1,2, Jeongah Oh3,4
1Signature Research Program in Cardiovascular and Metabolic Disorders and.
Abstract:
Patients with autosomal recessive microcephaly 15 caused by deficiency in the sodium-dependent lysophosphatidylcholine (LPC) transporter major facilitator superfamily domain-containing 2a (Mfsd2a) present with both microcephaly and hypomyelination, suggesting an important role for LPC uptake by oligodendrocytes in the process of myelination. Here we demonstrate that Mfsd2a is specifically expressed in oligodendrocyte precursor cells (OPCs) and is critical for oligodendrocyte development. Single-cell sequencing of the oligodendrocyte lineage revealed that OPCs from OPC-specific Mfsd2a-KO mice (2aOKO mice) underwent precocious differentiation into immature oligodendrocytes and impaired maturation into myelinating oligodendrocytes, correlating with postnatal brain hypomyelination. 2aOKO mice did not exhibit microcephaly, a finding consistent with the notion that microcephaly is the consequence of an absence of LPC uptake at the blood-brain barrier rather than a deficiency in OPCs. Lipidomic analysis showed that OPCs and iOLs from 2aOKO mice had significantly decreased levels of phospholipids containing omega-3 fatty acids, with a corresponding increase in unsaturated fatty acids, the latter being products of de novo synthesis governed by Srebp-1. RNA-Seq indicated activation of the Srebp-1 pathway and defective expression of regulators of oligodendrocyte development. Taken together, these findings indicate that the transport of LPCs by Mfsd2a in OPCs is important for maintaining OPC state to regulate postnatal brain myelination.
Insights
Major facilitator superfamily domain-containing 2a (Mfsd2a) is crucial for oligodendrocyte development and brain myelination by regulating lysophosphatidylcholine (LPC) uptake in precursor cells.
Area of Science:
- Neuroscience
- Cell Biology
- Genetics
Background:
- Autosomal recessive microcephaly 15 is linked to Mfsd2a deficiency, causing microcephaly and hypomyelination.
- Lysophosphatidylcholine (LPC) uptake by oligodendrocytes is implicated in myelination.
- Mfsd2a is a sodium-dependent LPC transporter.
Purpose of the Study:
- To investigate the role of Mfsd2a in oligodendrocyte precursor cells (OPCs) and brain myelination.
- To determine the impact of Mfsd2a deficiency in OPCs on oligodendrocyte development and maturation.
- To elucidate the molecular mechanisms underlying Mfsd2a's function in myelination.
Main Methods:
- Generation of OPC-specific Mfsd2a-knockout (2aOKO) mice.
- Single-cell sequencing of the oligodendrocyte lineage.
- Lipidomic analysis and RNA sequencing (RNA-Seq).
Main Results:
- Mfsd2a is specifically expressed in OPCs and is essential for their proper development.
- OPCs in 2aOKO mice showed precocious differentiation and impaired maturation into myelinating oligodendrocytes.
- 2aOKO mice exhibited postnatal brain hypomyelination but not microcephaly.
- Deficiencies in omega-3 fatty acid phospholipids and altered unsaturated fatty acid levels were observed in 2aOKO OPCs and immature oligodendrocytes (iOLs).
- Activation of the Srebp-1 pathway and defective expression of oligodendrocyte development regulators were indicated by RNA-Seq.
Conclusions:
- Mfsd2a-mediated LPC transport in OPCs is vital for maintaining OPC state.
- This process is critical for regulating postnatal brain myelination.
- Mfsd2a deficiency in OPCs disrupts oligodendrocyte maturation and leads to hypomyelination, distinct from the microcephaly phenotype.
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