Disease relevance of Notum

• Susceptibility to Heat Stress and Aberrant Gene Expression Patterns in Holocarboxylase Synthetase-Deficient Drosophila melanogaster Are Caused by Decreased Biotinylation of Histones, Not of Carboxylases [1].

High impact information on Notum

• Wingful, an extracellular feedback inhibitor of Wingless [2].
• Cell division: Not all are born equal [3].
• The Iroquois complex (Iro-C) homeodomain proteins allow cells at the proximal part of the Drosophila imaginal wing disc to form mesothoracic body wall (notum) [4].
• We have identified a novel gene, eyelid (eld), which is required for embryonic segmentation, development of the notum and wing margin, and photoreceptor differentiation [5].
• The pattern of the large sensory bristles on the notum of Drosophila arises as a consequence of the expression of the achaete and scute genes [6].

Biological context of Notum

• Here we report on the expression of a Notum homolog during the embryonic development of the spider Cupiennius salei [7].
• Flies homozygous for strong ds hypomorphic alleles display previously uncharacterized phenotypes consisting of a reduction of the hinge territory and an ectopic notum [8].
• Expression of the Iroquois complex (Iro-C) homeobox genes in the most proximal part of the disc defines the notum, since Iro-C(-) cells within this territory acquire the identity of the adjacent distal region, the wing hinge [9].
• This downregulation is associated with the subdivision of the notum into medial and lateral regions [9].
• When expressed in the notum, truncated Mam results in failure of lateral inhibition within proneural clusters and perturbations in cell fate specification within the sensory organ precursor cell lineage [10].

Anatomical context of Notum

• During development, the imaginal wing disc of Drosophila is subdivided along the proximal-distal axis into different territories that will give rise to body wall (notum and mesothoracic pleura) and appendage (wing hinge and wing blade) [9].
• Cytoskeletal changes occurring during the delamination of precursors of the peripheral (microchaete precursors in the pupal notum) and central nervous system (embryonic SI neuroblasts) were studied [11].
• The Drosophila notum, the dorsal body wall of the thorax, is subdivided genetically into longitudinal domains (Calleja, M., Moreno, E., Pelaz, S. and Morata, G. (1996) Science 274, 252-255) [12].
• Here we describe the temporal pattern of appearance and divisions of the sensory mother cells that will form the eleven macrochaetes and the two trichoid sensilla of the notum, and five campaniform sensilla on the wing blade [13].
• A glial cell arises from an additional division within the mechanosensory lineage during development of the microchaete on the Drosophila notum [14].

Physical interactions of Notum

• Thus, spatially regulated modification of Dlp by Notum employs the ligand binding activity of Dlp to promote or inhibit signaling in a context-dependent manner [15].

Regulatory relationships of Notum

• When overexpressed, Notum blocks Wingless activity [16].
• Notum-induced shedding of Dlp could convert Dlp from a membrane-tethered coreceptor to a secreted antagonist [15].
• Later, Dpp becomes expressed in the most proximal part of the notum and turns off Iro-C in this region [9].
• In the absence of eyg function the anterior-central region does not develop, whereas ectopic activity of either eyg or toe induces the formation of the anterior-central pattern in the posterior or lateral region of the notum [17].
• The iroquois complex controls the somatotopy of Drosophila notum mechanosensory projections [18].

Other interactions of Notum

• In the appendages, Notum is expressed in ventral mesodermal cells, directly adjacent to the Wingless expressing ectodermal cells [7].
• At early second larval instar, the Dpp signalling pathway functions only in the wing and hinge territories, represses Iro-C and confines its expression to the notum territory [9].
• In the wing disc, ds is first expressed distally, and later is restricted to the hinge and lateral regions of the notum [8].
• Here we show that antagonizing DER signaling during the second larval instar leads to notum to wing transformations and wing mirror-image duplications [19].
• In the wing disc, DWnt4 phenocopies ectopic Wg activity by inducing notum to wing transformation, suggesting similar signaling capabilities of both molecules [20].

References