Her decision comes in the wake of a shake-up of the commissioning structure, in which she was to lose control of commissioning responsibilities for comedy, entertainment, music and youth programming on T4 and E4.
Lux's reign over the crucial youth, comedy and entertainment at Channel 4 has coincided with accusations that the channel has been losing some of its much-vaunted edgy innovation.
This is why, according to many, there has been a reliance on the station's biggest property, 'Big Brother' -- and its various reality TV cousins such as 'The Salon' and 'Big Brother USA' -- which, while it has given Channel 4 a hit in ratings this year, backfired as 'Big Brother' turned into big bore.
Much of the shake-up in commissioning is connected with the arrival of director of programmes Lygo, who is known to have wanted control over commissioning and so will take on Lux's responsibilities when he arrives from Five in November, after two years away from the station.
When at Channel 4 before his stint at Five, Lygo was responsible for some of its top rated shows such as 'So Graham Norton', 'Trigger Happy TV', 'Smack the Pony', 'Spaced', 'Black Books' and 'The Ali G Show'.
According to Lux: "Given his track record, it's no surprise that Kevin wants to take direct charge of Channel 4's entertainment and I wish him well."
Channel 4 chief executive Mark Thompson said: "Danielle has been a valued member of the commissioning team and we are sorry the change in the commissioning structure has triggered this move."
During her time at Channel 4, Lux is credited with working on some of its most popular shows, including 'Bo Selecta', 'Derren Brown's Mind Control' and 'My New Best Friend', contributing to a record five awards at this year's Montreux TV festival. She also leaves viewers with Peter Kay's 'Max and Paddy', featuring the intellectually challenged bouncers from 'Phoenix Nights', to look forward to in 2004.
Lux's next move is uncertain, but she is said to be exploring a number of options outside the channel.
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