Guardian News & Media's director of digital content, Emily Bell, is to leave the company after nearly 18 years to move into academia at Columbia University.
Bell, who will leave the Guardian in July, is to become the first director of the recently-established Tow Center for Digital Journalism at Columbia University's Graduate School of Journalism in New York.
As a faculty member she will teach graduate students, oversee research projects, while also studying and collaborating with new organisations, and develop and test new models for creating and delivering information.
GNM said today that Bell, who was at the forefront of the company's groundbreaking push into digital publishing, would continue to work and write for the Guardian on a consultancy basis.
Bell's departure follows that of Carolyn McCall, chief executive of parent group Guardian Media Group, who announced last month that she was to step down after 24 years with the newspaper group to head Easyjet.
Janine Gibson, editor of Guardian.co.uk, will assume a wider strategic role in addition to her present duties. She will be responsible for all digital output at GNM.
Alan Rusbridger, GNM editor-in-chief, said: "Emily Bell has done a brilliant job helping to create a website which has won numerous awards and which has nearly 37 million unique users - one of the most used and garlanded news websites in the world.
"It's a mark of that thought leadership that the prestigious faculty at Columbia School of Journalism should turn to a British newspaper for someone to head its new centre for digital studies.
"We will not be losing Emily: she will continue as a consultant to the Guardian, giving strategic advice from her new base in New York."
Rusbridger added that GNM would be making further announcements about the development of the Guardian's digital content "in due course".
Bell said: "It has been a privilege and my great good luck to work for such a unique and special organisation as the Guardian for so long.
"It is like a second family to me so I hope to maintain strong links even from across the Atlanticâ€¦Being asked to join the distinguished journalism faculty at Columbia as director of the Tow Center is an incredible honour and represents a once in a lifetime opportunity to help reshape the future of journalism at this critical time."