Complex sentence: The publication of the novel has led Leskov's severing all ties with "The Russian Messenger", the main issue being the magazine's editor Mikhail Katkov's disagreement with the author's position as regards Russian dvoryanstvo.
Split into simpler sentences: The publication of the novel has led to Leskov's severing all ties with "The Russian Messenger". The main issue was the magazine's editor-in-chief Mikhail Katkov's disagreement with the author's position as regards Russian dvoryanstvo.