The Gospel of the Transfiguration does not mention any role played by Mary, but the tradition of the Church, particularly St. Gregory Palamas in the East, speaks of Mary's role in similar experiences of contact with the divine glory, or deification.
Gregory Palamas insists that our deification is not only possible but real; while remaining creatures, we will participate in the divine nature and in the divine life, through the divine energies. Mary was the first to achieve this by grace.
Then, considering the mystery of the Church as a communion of deification, Saint Gregory Palamas explains that Mary puts us in contact with the divine life, and that this contact transfigures us. The Eastern Fathers actually say that this contact deifies us and makes us participants in the divine life.
The Marie de Nazareth team