To more precisely determine specific tissue(s) in which loss ofkisfunction affects this behavior, we expressed theUAS:kis RNAiconstructs with a number of different tissue specific Gal4 drivers (Fig.2, Table1). loss-of-function mutations in theChd7gene were first described as associated with CS in 2004 (1), and since have been estimated to be causative for nearly two-thirds of all CS diagnoses (2), underscoring the importance of analysis ofChd7function in this disease. CS is characterized by a variety of clinical symptoms and is prevalent in approximately one in every 10 000 live births (3). Although the clinical symptoms of CS vary from case to case, the clinical definition of CS initially relied on six basic symptoms: coloboma, heart malformation, choanal atresia, retardation of growth and/or development, genital anomalies and ear anomalies, making CS a common cause of congenital anomalies (2). Though these clinical symptoms alone can often suggest a diagnosis of CS, the literature stresses the importance of coupling this clinical diagnosis with a molecular diagnosis, through mutational analysis ofChd7(25).Chd7encodes an evolutionarily conserved protein thought to play a role in the regulation of gene expression through chromatin remodeling (1). Recent studies of Chd7 DNA-binding sites on chromatin have Rabbit Polyclonal to AIBP shown that Chd7 binding is correlated to areas of mono- and dimethylated lysine 4 of histone (R)-P7C3-Ome H3 (6), consistent with Chd7 serving a role in mediating transcription through chromatin remodeling. Attempts to understand the complex etiology of many human diseases have been improved through the study of model organisms. The fruit fly,Drosophila melanogaster, has been tremendously important and influential in furthering our understanding of the molecular and cellular mechanisms of gene function in a variety of human diseases, including neurodegenerative diseases and forms of hereditary mental retardation. We therefore sought to utilize the (R)-P7C3-Ome fly in an attempt to understand the (R)-P7C3-Ome basic functions of theDrosophilahomolog of mammalianChd7in behavior and neural development. Literature suggests that theDrosophilahomolog ofChd7is thekismet(kis) gene (714). Searches of the NCBI Homologene database and information (R)-P7C3-Ome hyperlinked over proteins databases also listkisas the fly homolog of humanChd7. Finally, an NCBI Protein BLAST of the human CHD7 protein (NP_060250.2) lists the Kismet protein as the protein with the highest degree of similarity and identity withinDrosophila(E value 0.0). CHD7 belongs to a subfamily of proteins in mammals that includes CHD6, CHD7, CHD8 and CHD9 (13), collectively referred to as subgroup III (12). Literature has suggested that Kismet protein function in flies is carried out by the proteins within this subfamily III group in mammals (12,13), consistent with the protein sequence homology shared by Kismet and this group of proteins. Taken together, this suggests that the Kismet protein is most closely related to the Bilaterian ancestral protein that fly Kismet (R)-P7C3-Ome and human CHD6, CHD7, CHD8 and CHD9 evolved from 670 million years ago (15). Recently, Batsukhet al. (12) have shown that CHD7 interacts with family member CHD8 both directly and indirectly to form a potential CHD7/CHD8 complex. Based on the literature showing that in other diseases (Hereditary Spastic Paraplegia and Cornelia de Lange syndrome), interacting partners are involved in the underlying cause of the disease, these authors suggest that a CHD7/CHD8 containing complex may be involved in the pathogenesis of CS (12). A major advantage ofDrosophilaas a model system for the study of human disease is the ability to study the functions of genes whose mammalian homologs exist in multi-gene families, in order to gain a deeper understanding of the evolutionarily conserved functions and relationships between these genes. Given that 1) CHD7 is the closest human homolog based on sequence identity to fly Kismet; 2) CHD7 and CHD8 family members are both homologous to the Kismet protein; and 3) CHD7 and CHD8 interact to potentially contribute to CHARGE pathogenesis, determining the functions ofkismetin neural development and behavior may significantly contribute to our understanding of the function of both CHD7 and CHD8 in CS pathogenesis. TheDrosophila kismetgene encodes for two protein products (Kis-L and Kis-S) which share a common C terminal stretch of 2100 amino acids (16). The common C terminal segment contains a BRK domain of unknown function, whereas the N-terminal domain of Kis-L also contains an ATPase domain similar to those found in other chromatin remodeling enzymes and two chromodomains which can recognize Histone H3 methylation (16). Importantly, the BRK domain, as well as the ATPase and chromodomains found in the Kismet protein are also conserved in humanChd7(8), suggesting that theDrosophilaprotein is a good candidate to study in order to better understand human Chd7 protein function. kiswas initially identified in a genetic screen as a suppressor of a dominant homeotic phenotype and as a member of thetrithoraxgroup.