Knockdown of slit signaling during limb development leads to a reduction in humerus length

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Slits (1–3) and their Robo (1–3) receptors play multiple non‐neuronal roles in development, including in development of muscle, heart and mammary gland. Previous work has demonstrated expression of <jats:italic>Slit</jats:italic> and <jats:italic>Robo</jats:italic> family members during limb development, where their functions are unclear.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>In situ hybridisation confirmed strong expression of <jats:italic>Slit2</jats:italic>, <jats:italic>Slit3</jats:italic>, <jats:italic>Robo1</jats:italic>, and <jats:italic>Robo2</jats:italic> throughout mouse limb and joint development. No expression of <jats:italic>Slit1</jats:italic> or <jats:italic>Robo3</jats:italic> was detected. Analysis of <jats:italic>Slit1/2</jats:italic> or <jats:italic>Slit3</jats:italic> knockout mice revealed normal limb development. In contrast, locally blocking Slit signaling though grafting of cells expressing a dominant‐negative <jats:italic>Robo2</jats:italic> construct in the proximo‐central region of developing chicken limb buds caused significant shortening of the humerus.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>These findings demonstrate an essential role for Slit/Robo signaling in regulating bone length during chicken limb development.</jats:p></jats:sec>