@article {8062, title = {CRISPR/Cas9 and FLP-FRT mediated regulatory dissection of the BX-C of Drosophila melanogaster [Transgenic Fly Facility]}, journal = {Chromosome Res}, volume = {31}, year = {2023}, month = {2023 Jan 31}, pages = {7}, abstract = {

The homeotic genes or Hox define the anterior-posterior (AP) body axis formation in bilaterians and are often present on the chromosome in an order collinear to their function across the AP axis. However, there are many cases wherein the Hox are not collinear, but their expression pattern is conserved across the AP axis. The expression pattern of Hox is attributed to the cis-regulatory modules (CRMs) consisting of enhancers, initiators, or repressor elements that regulate the genes in a segment-specific manner. In the Drosophila melanogaster Hox complex, the bithorax complex (BX-C) and even the CRMs are organized in an order that is collinear to their function in the thoracic and abdominal segments. In the present study, the regulatorily inert regions were targeted using CRISPR/Cas9 to generate a series of transgenic lines with the insertion of FRT sequences. These FRT lines are repurposed to shuffle the CRMs associated with Abd-B to generate modular deletion, duplication, or inversion of multiple CRMs. The rearrangements yielded entirely novel phenotypes in the fly suggesting the requirement of such complex manipulations to address the significance of higher order arrangement of the CRMs. The functional map and the transgenic flies generated in this study are important resources to decipher the collective ability of multiple regulatory elements in the eukaryotic genome to function as complex modules.

}, keywords = {Animals, CRISPR-Cas Systems, Drosophila melanogaster, Drosophila Proteins, Gene Expression Regulation, Developmental, Homeodomain Proteins, Regulatory Sequences, Nucleic Acid}, issn = {1573-6849}, doi = {10.1007/s10577-023-09716-w}, author = {Hajirnis, Nikhil and Pandey, Shubhanshu and Mishra, Rakesh K} } @article {1458, title = {The Hox gene uses Doublesex as a cofactor to promote neuroblast apoptosis in the central nervous system [Transgenic Fly Facility]}, journal = {Development}, volume = {146}, year = {2019}, month = {2019 08 22}, abstract = {

Highly conserved DM domain-containing transcription factors (Doublesex/MAB-3/DMRT1) are responsible for generating sexually dimorphic features. In the central nervous system, a set of Doublesex (Dsx)-expressing neuroblasts undergo apoptosis in females whereas their male counterparts proliferate and give rise to serotonergic neurons crucial for adult mating behaviour. Our study demonstrates that the female-specific isoform of Dsx collaborates with Hox gene () to bring about this apoptosis. Biochemical results suggest that proteins AbdB and Dsx interact through their highly conserved homeodomain and DM domain, respectively. This interaction is translated into a cooperative binding of the two proteins on the apoptotic enhancer in the case of females but not in the case of males, resulting in female-specific activation of apoptotic genes. The capacity of AbdB to use the sex-specific isoform of Dsx as a cofactor underlines the possibility that these two classes of protein are capable of cooperating in selection and regulation of target genes in a tissue- and sex-specific manner. We propose that this interaction could be a common theme in generating sexual dimorphism in different tissues across different species.

}, keywords = {Animals, Apoptosis, DNA-Binding Proteins, Drosophila, Drosophila Proteins, Female, Gene Expression Regulation, Developmental, Genes, Homeobox, Homeodomain Proteins, Male, Neural Stem Cells, Protein Isoforms, Sex Characteristics}, issn = {1477-9129}, doi = {10.1242/dev.175158}, author = {Ghosh, Neha and Bakshi, Asif and Khandelwal, Risha and Rajan, Sriivatsan Govinda and Joshi, Rohit} } @article {683, title = {Combinatorial action of Grainyhead, Extradenticle and Notch in regulating Hox mediated apoptosis in Drosophila larval CNS.}, journal = {PLoS Genet}, volume = {13}, year = {2017}, month = {2017 Oct}, pages = {e1007043}, abstract = {

Hox mediated neuroblast apoptosis is a prevalent way to pattern larval central nervous system (CNS) by different Hox genes, but the mechanism of this apoptosis is not understood. Our studies with Abdominal-A (Abd-A) mediated larval neuroblast (pNB) apoptosis suggests that AbdA, its cofactor Extradenticle (Exd), a helix-loop-helix transcription factor Grainyhead (Grh), and Notch signaling transcriptionally contribute to expression of RHG family of apoptotic genes. We find that Grh, AbdA, and Exd function together at multiple motifs on the apoptotic enhancer. In vivo mutagenesis of these motifs suggest that they are important for the maintenance of the activity of the enhancer rather than its initiation. We also find that Exd function is independent of its known partner homothorax in this apoptosis. We extend some of our findings to Deformed expressing region of sub-esophageal ganglia where pNBs undergo a similar Hox dependent apoptosis. We propose a mechanism where common players like Exd-Grh-Notch work with different Hox genes through region specific enhancers to pattern respective segments of larval central nervous system.

}, keywords = {Amino Acid Sequence, Animals, Apoptosis, Central Nervous System, DNA-Binding Proteins, Drosophila, Drosophila Proteins, Enhancer Elements, Genetic, Female, Gene Expression Regulation, Developmental, Genes, Homeobox, Homeodomain Proteins, Larva, Male, Nuclear Proteins, Receptors, Notch, Transcription Factors}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1007043}, author = {Khandelwal, Risha and Sipani, Rashmi and Govinda Rajan, Sriivatsan and Kumar, Raviranjan and Joshi, Rohit} } @article {684, title = {Role of Homothorax in region specific regulation of Deformed in embryonic neuroblasts.}, journal = {Mech Dev}, volume = {138 Pt 2}, year = {2015}, month = {2015 Nov}, pages = {190-7}, abstract = {

The expression and regulation of Hox genes in developing central nervous system (CNS) lack important details like specific cell types where Hox genes are expressed and the transcriptional regulatory players involved in these cells. In this study we have investigated the expression and regulation of Drosophila Hox gene Deformed (Dfd) in specific cell types of embryonic CNS. Using Dfd neural autoregulatory enhancer we find that Dfd autoregulates itself in cells of mandibular neuromere. We have also investigated the role of a Hox cofactor Homothorax (Hth) for its role in regulating Dfd expression in CNS. We find that Hth exhibits a region specific role in controlling the expression of Dfd, but has no direct role in mandibular Dfd neural autoregulatory circuit. Our results also suggest that homeodomain of Hth is not required for regulating Dfd expression in embryonic CNS.

}, keywords = {Animals, Central Nervous System, Drosophila, Drosophila Proteins, Enhancer Elements, Genetic, Gene Expression Regulation, Developmental, Genes, Homeobox, Homeodomain Proteins, Neural Stem Cells, Organogenesis}, issn = {1872-6356}, doi = {10.1016/j.mod.2015.09.003}, author = {Kumar, Raviranjan and Chotaliya, Maheshvari and Vuppala, Sruthakeerthi and Auradkar, Ankush and Palasamudrum, Kalyani and Joshi, Rohit} }