Matt Proudfoot has left his role as England forwards coach less than a month after Eddie Jones' departure as head coach.
A South Africa-born former Scotland international, Proudfoot took on the forwards coach role in January 2020 after Neal Hatley's departure to Bath.
He previously served as a Springboks assistant in their 2019 World Cup win.
Conor O'Shea, the RFU's executive director of performance rugby, said: "We are very grateful to Matt for all he has done for England and wish him every success in his next career move."
Proudfoot said it had been a "privilege" to work with the England set-up.
Borthwick's appointment as England head coach was confirmed on 19 December.
The former Leicester Tigers coach had long been seen as Jones' successor after the World Cup, but that process was brought forward to before the Six Nations after some poor results for England in 2022, including defeats to Argentina and Scotland.
The RFU have also announced that Brett Hodgson and Danny Kerry have left the England coaching team.
Hodgson never actually coached an England game as his appointment was made by Jones during the Autumn Internationals and he shadowed then defence coach Anthony Seibold during that period.
The Australian is being replaced by Kevin Sinfield, previously Borthwick's defence coach at Leicester.