Originally published as Genetics Published Articles Ahead of Print on August 24, 2008.

Genetics, Vol. 180, 133-145, September 2008, Copyright © 2008
doi:10.1534/genetics.108.091371

Tissue-Specific Defects Are Caused by Loss of the Drosophila MAN1 LEM Domain Protein

Belinda S. Pinto*, Shameika R. Wilmington{dagger}, Emma E. L. Hornick{dagger}, Lori L. Wallrath*,{dagger} and Pamela K. Geyer*,{dagger},1

* Molecular and Cellular Biology Program and {dagger} Department of Biochemistry, University of Iowa, College of Medicine, Iowa City, Iowa 52242

1 Corresponding author: 3135E MERF, University of Iowa, Iowa City, IA 52242.
E-mail: pamela-geyer{at}uiowa.edu

The nuclear lamina represents a protein network required for nuclear structure and function. One family of lamina proteins is defined by an ~40-aa LAP2, Emerin, and MAN1 (LEM) domain (LEM-D) that binds the nonspecific DNA-binding protein, barrier-to-autointegration factor (BAF). Through interactions with BAF, LEM-D proteins serve as a bridge between chromosomes and the nuclear envelope. Mutations in genes encoding LEM-D proteins cause human laminopathies that are associated with tissue-restricted pathologies. Drosophila has five genes that encode proteins with LEM homology. Using yeast two-hybrid analyses, we demonstrate that four encode proteins that bind Drosophila (d)BAF. In addition to dBAF, dMAN1 associates with lamins, the LEM-D protein Bocksbeutel, and the receptor-regulated Smads, demonstrating parallel protein interactions with vertebrate homologs. P-element mobilization was used to generate null dMAN1 alleles. These mutants showed decreased viability, with surviving adults displaying male sterility, decreased female fertility, wing patterning and positioning defects, flightlessness, and locomotion difficulties that became more severe with age. Increased phospho-Smad staining in dMAN1 mutant wing discs is consistent with a role in transforming growth factor (TGF)-β/bone morphogenic protein (BMP) signaling. The tissue-specific, age-enhanced dMAN1 mutant phenotypes are reminiscent of human laminopathies, suggesting that studies in Drosophila will provide insights into lamina dysfunction associated with disease.