J Sainsbury has appointed the former finance director of Next as a non-executive director and chairman of the supermarket's audit committee.David Keens will join Sainsbury's on 29 April. He succeeds Gary Hughes who will be stepping down as chairman at the company's annual general meeting in July, at which point Mr Keens will take over his responsibilities as chairman of the audit committee.Chairman David Tyler said Keens' "deep retail experience" and his knowledge of fast-moving consumer business were "particularly relevant at a time when we are growing our own successful non-food ranges". The news come a week after the group announced it would be axing 800 jobs as part of cost cuts, which are expected to save £500m over the next three years.A supermarket price war amid fierce competition from smaller discounters has prompted Sainsbury's to slash costs.