The protein encoded by the Drosophila gene dlg1 is a component of the Scribble polarity complex, which plays a key role in determining cell polarity and cell proliferation in epithelial cells. Loss of apical-basal polarity is an early event in the development of epithelial cancers. See also human diseases model reports 'cancer, epithelial, Scribble-complex-related' (FBhh0000586), and 'cancer, epithelial, RAS-DLG1-related' (FBhh0000589).
In human, there are four genes orthologous to Dmel\dlg1, DLG1 (a component of the Scribble polarity complex), DLG2, DLG3, and DLG4. Although the human Hsap\DLG4 gene has been introduced into flies, DLG1 has not. Classical loss-of-function alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated for Dmel\dlg1.
Animals homozygous for loss-of-function mutations of Dmel\dlg1 typically die during the larval stage; tumors of the brain and imaginal discs are observed; defects associated with neuromuscular junctions are observed. Knockdown of dlg1 in larval imaginal discs, effected by RNAi, results in apoptosis and an invasion-like phenotype in which cells delaminated and migrated away from the site of origin within the wing disc epithelium; however, most of these animals survive to adulthood, displaying scars along the anterior/posterior boundary of the wing blade, indicating that a mechanism to eliminate the abnormal cells comes into play. Many physical and genetic interactions for Dmel\dlg1 have been described; see below and in the gene report for dlg1.
[updated Nov. 2018 by FlyBase; FBrf0222196]