Dual Role of DLK1 in GnRH Neuron Ontogeny

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Mutations in the DLK1 gene are linked to central precocious puberty (CPP).
• The precise mechanism by which DLK1 influences GnRH neuron development is unknown.
• DLK1 is a paternally expressed imprinted gene crucial in development.

Purpose of the Study:

• To investigate the role of DLK1 in the development of GnRH neurons.
• To determine if DLK1 loss-of-function impacts GnRH neuron ontogeny.
• To explore the effect of DLK1 expression timing on GnRH neuron differentiation.

Main Methods:

• CRISPR-Cas9 was used to delete DLK1 exon 3 in human pluripotent stem cells (hPSCs).
• CRISPR activation (CRISPRa) was employed to modulate DLK1 expression.
• hPSCs were differentiated into GnRH neurons using dual SMAD inhibition (dSMADi), FGF8, and Notch inhibition.

Main Results:

• DLK1 loss-of-function in hPSCs did not accelerate GNRH1 expression.
• Early DLK1 activation during differentiation suppressed GnRH neuron fate and induced alternative neuronal progenitor markers.
• Later DLK1 activation enhanced GNRH1 expression and GnRH decapeptide secretion.

Conclusions:

• Paternally inherited loss-of-function DLK1 mutations causing CPP likely act via mechanisms upstream or downstream of GnRH neurons.
• The timing of DLK1 expression is critical for GnRH neuron lineage commitment and development.
• Early DLK1 expression can disrupt neurodevelopmental trajectories, while later expression supports GnRH neuron maturation.