High impact information on kn

• We further show that attenuation of Dpp signalling in the AP organiser is also col dependent and, in conjunction with Vein upregulation, required for formation of L4 vein [1].
• During wing development, Hh also has morphogen-like Dpp-independent functions, controlling the morphogenesis of the central part of the wing through the activation of the evolutionarily conserved transcription factors encoded by the iroquois and collier genes [2].
• The parasegmental register of col activation is controlled by the combined activities of the head-gap genes buttonhead and empty spiracles and the pair-rule gene even skipped; it therefore integrates inputs from both the head and trunk segmentation systems, which were previously considered as being essentially independent [3].
• In wild-type embryos, each of the DA3([A])-recruited myoblasts turns on col transcription, indicating that the conversion, by the DA3([A]) founder cell, of 'naive' myoblasts to express its distinctive pattern of gene expression involves activation of col itself [4].
• After gastrulation, positive autoregulation of col is limited to cells of anterior PS0 [3].

Biological context of kn

• In col mutant embryos, the DA3([A]) founder cells form but do not maintain col transcription and are unable to fuse with neighbouring myoblasts, leading to a loss-of-muscle DA3([A]) phenotype [4].

Anatomical context of kn

• Reduction of col activity in early gastrula embryos by antisense RNA expression results in a specific lack of head structures derived from these segments [5].
• RESULTS: We have identified a new Drosophila gene, collier (col), whose expression at the blastoderm stage is restricted to a single stripe of cells corresponding to part of the intercalary and mandibular segment primordia, possibly parasegment O [5].
• Further investigations on Col/EBF expression and function in other phyla should provide fresh insight into the evolutionary origin of lymphoid cells [6].
• We first show that collier (col), the Drosophila orthologue of the vertebrate gene encoding early B-cell factor (EBF), is expressed very early during ontogeny of the lymph gland, the larval hematopoietic organ [6].

Other interactions of kn

• The COE transcription factor Collier is a mediator of short-range Hedgehog-induced patterning of the Drosophila wing [7].
• Connecting Hh, Dpp and EGF signalling in patterning of the Drosophila wing; the pivotal role of collier/knot in the AP organiser [1].
• Instead we find that kn has a specific role in those cells of the wing imaginal disc that are subject to ptc-mediated Hh-signaling [8].
• However, unlike fu, strong kn mutations do not affect embryonic segmentation and indicate that kn is not a component of a general Hh (Hedgehog)-signaling pathway [8].
• This restriction which depends upon Notch (N) signaling sets the L3 and L4 vein primordia off the boundaries of Col expression [9].

References