@article {159719, title = {K. VijayRaghavan.}, journal = {Curr Biol}, volume = {35}, year = {2025}, month = {2025 Jul 21}, pages = {R695-R697}, abstract = {

Interview with K. VijayRaghavan, who studies the development of muscles and the nervous system at the Tata Institute of Fundamental Research.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2025.06.026}, author = {VijayRaghavan, K} } @article {160478, title = {A Scientist Who Created Institutions With a Lasting Culture}, journal = {Reson }, volume = {30, 1037{\textendash}1053. }, year = {2025}, doi = {https://doi.org/10.1007/s12045-025-1846-6 }, author = {VijayRaghavan, K} } @article {108048, title = {A DROSOPHILA CIRCUIT FOR HABITUATION OVERRIDE.}, journal = {J Neurosci}, year = {2022}, month = {2022 Feb 25}, abstract = {

Habituated animals retain a latent capacity for robust engagement with familiar stimuli. In most instances, the ability to override habituation is best explained by postulating that habituation arises from the potentiation of inhibitory inputs onto stimulus-encoding assemblies and that habituation override occurs through disinhibition. Previous work has shown that inhibitory plasticity contributes to specific forms of olfactory and gustatory habituation in Here we analyze how exposure to a novel stimulus causes override of gustatory (proboscis-extension reflex or "PER") habituation. While brief sucrose contact with tarsal hairs causes na{\"\i}ve to extend their proboscis, persistent exposure reduces PER to subsequent sucrose stimuli. We show that in so habituated animals, either brief exposure of the proboscis to yeast or direct thermogenetic activation of sensory neurons restores PER response to tarsal sucrose stimulation. Similar override of PER habituation can also be induced by brief thermogenetic activation of a population of TH (Tyrosine-Hydroxylase) positive neurons, a subset of which send projections to the subesophagial zone (SEZ). Significantly, sensory-neuron induced habituation override requires transmitter release from these TH-positive cells. Treatments that cause override specifically influence the habituated state, with no effect on the na{\"\i}ve sucrose response across a range of concentrations. Taken together with other findings, these observations in female flies are consistent with a model in which novel taste stimuli trigger activity in dopaminergic neurons which, directly or indirectly, inhibit GABAergic cells that drive PER habituation. The implications of these findings for general mechanisms of attentional and sensory override of habituation are discussed.Habituation can be overcome when a new context requires an enhanced response to a familiar stimulus. However, the underlying mechanisms remain incompletely understood. Previous studies have provided evidence that habituation of the sucrose-induced proboscis extension reflex (PER) in Drosophila occurs through potentiation of inhibition onto the PER pathway. This work defines controlled protocols for override of PER habituation and uses them to outline the underlying circuit mechanisms. The results presented support a model in which novel taste stimuli cause dishabituation by activating a subset of tyrosine-hydroxylase-expressing neurons that inhibit GABAergic neurons whose potentiation underlies PER habituation. At a general level, these findings further highlight a central role for inhibition and disinhibition in the control of behavioral flexibility.

}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.1842-21.2022}, author = {Trisal, Swati and Aranha, Marcia and Chodankar, Ankita and VijayRaghavan, K and Ramaswami, Mani} } @article {110624, title = {Local translation provides the asymmetric distribution of CaMKII required for associative memory formation.}, journal = {Curr Biol}, year = {2022}, month = {2022 May 04}, abstract = {

How compartment-specific local proteomes are generated and maintained is inadequately understood, particularly in neurons, which display extreme asymmetries. Here we show that local enrichment of Ca/calmodulin-dependent protein kinase II (CaMKII) in axons of Drosophila mushroom body neurons is necessary for cellular plasticity and associative memory formation. Enrichment is achieved via enhanced axoplasmic translation of CaMKII mRNA, through a mechanism requiring the RNA-binding protein Mub and a 23-base Mub-recognition element in the CaMKII 3{\textquoteright} UTR. Perturbation of either dramatically reduces axonal, but not somatic, CaMKII protein without altering the distribution or amount of mRNA in\ vivo, and both are necessary and sufficient to enhance axonal translation of reporter mRNA. Together, these data identify elevated levels of translation of an evenly distributed mRNA as a novel strategy for generating subcellular biochemical asymmetries. They further demonstrate the importance of distributional asymmetry in the computational and biological functions of neurons.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2022.04.047}, author = {Chen, Nannan and Zhang, Yunpeng and Adel, Mohamed and Kuklin, Elena A and Reed, Martha L and Mardovin, Jacob D and Bakthavachalu, Baskar and VijayRaghavan, K and Ramaswami, Mani and Griffith, Leslie C} } @article {90598, title = {Antagonistic roles for Ataxin-2 structured and disordered domains in RNP condensation.}, journal = {Elife}, volume = {10}, year = {2021}, month = {2021 Mar 10}, abstract = {

Ataxin-2 (Atx2) is a translational control molecule mutated in spinocerebellar ataxia type II and amyotrophic lateral sclerosis. While intrinsically disordered domains (IDRs) of Atx2 facilitate mRNP condensation into granules, how IDRs work with structured domains to enable positive and negative regulation of target mRNAs remains unclear. Using the Targets of RNA-Binding Proteins Identified by Editing technology, we identified an extensive data set of Atx2-target mRNAs in the brain and S2 cells. Atx2 interactions with AU-rich elements in 3{\textquoteright}UTRs appear to modulate stability/turnover of a large fraction of these target mRNAs. Further genomic and cell biological analyses of Atx2 domain deletions demonstrate that Atx2 (1) interacts closely with target mRNAs within mRNP granules, (2) contains distinct protein domains that drive or oppose RNP-granule assembly, and (3) has additional essential roles outside of mRNP granules. These findings increase the understanding of neuronal translational control mechanisms and inform strategies for Atx2-based interventions under development for neurodegenerative disease.

}, issn = {2050-084X}, doi = {10.7554/eLife.60326}, author = {Singh, Amanjot and Hulsmeier, Joern and Kandi, Arvind Reddy and Pothapragada, Sai Shruti and Hillebrand, Jens and Petrauskas, Arnas and Agrawal, Khushboo and Rt, Krishnan and Thiagarajan, Devasena and Jayaprakashappa, Deepa and VijayRaghavan, K and Ramaswami, Mani and Bakthavachalu, Baskar} } @article {89660, title = {Differential activation of JAK-STAT signaling reveals functional compartmentalization in blood progenitors.}, journal = {Elife}, volume = {10}, year = {2021}, month = {2021 Feb 17}, abstract = {

Blood cells arise from diverse pools of stem and progenitor cells. Understanding progenitor heterogeneity is a major challenge. The larval lymph gland is a well-studied model to understand blood progenitor maintenance and recapitulates several aspects of vertebrate hematopoiesis. However in-depth analysis has focused on the anterior lobe progenitors (AP), ignoring the posterior progenitors (PP) from the posterior lobes. Using expression mapping, developmental and transcriptome analysis we reveal PP heterogeneity and identify molecular-genetic tools to study this abundant progenitor population. Functional analysis shows that PP resist differentiation upon immune challenge, in a JAK-STAT-dependent manner. Upon wasp parasitism, AP downregulate JAK-STAT signaling and form lamellocytes. In contrast, we show that PP activate STAT92E and remain undifferentiated, promoting survival. knockdown or genetically reducing JAK-STAT signaling permits PP lamellocyte differentiation. We discuss how heterogeneity and compartmentalization allow functional segregation in response to systemic cues and could be widely applicable.

}, issn = {2050-084X}, doi = {10.7554/eLife.61409}, author = {Rodrigues, Diana and Renaud, Yoan and VijayRaghavan, K and Waltzer, Lucas and Inamdar, Maneesha S} } @article {80093, title = {Microtubules provide guidance cues for myofibril and sarcomere assembly and growth.}, journal = {Dev Dyn}, volume = {250}, year = {2021}, month = {07/2020}, pages = {60-73}, abstract = {

BACKGROUND: Muscle myofibrils and sarcomeres present exceptional examples of highly ordered cytoskeletal filament arrays, whose distinct spatial organization is an essential aspect of muscle cell functionality. We utilized ultra-structural analysis to investigate the assembly of myofibrils and sarcomeres within developing myotubes of the indirect flight musculature of Drosophila.

RESULTS: A temporal sequence composed of three major processes was identified: subdivision of the unorganized cytoplasm of nascent, multi-nucleated myotubes into distinct organelle-rich and filament-rich domains; initial organization of the filament-rich domains into myofibrils harboring nascent sarcomeric units; and finally, maturation of the highly-ordered pattern of sarcomeric thick (myosin-based) and thin (microfilament-based) filament arrays in parallel to myofibril radial growth. Significantly, organized microtubule arrays were present throughout these stages and exhibited dynamic changes in their spatial patterns consistent with instructive roles. Genetic manipulations confirm these notions, and imply specific and critical guidance activities of the microtubule-based cytoskeleton, as well as structural interdependence between the myosin- and actin-based filament arrays.

CONCLUSIONS: Our observations highlight a surprisingly significant, behind-the-scenes role for microtubules in establishment of myofibril and sarcomere spatial patterns and size, and provide a detailed account of the interplay between major cytoskeletal elements in generating these essential contractile myogenic units. This article is protected by copyright. All rights reserved.

}, issn = {1097-0177}, doi = {10.1002/dvdy.227}, author = {Dhanyasi, Nagaraju and VijayRaghavan, K and Shilo, Ben-Zion and Schejter, Eyal D} } @article {78110, title = {GLOMERULUS-SELECTIVE REGULATION OF A CRITICAL PERIOD FOR INTERNEURON PLASTICITY IN THE ANTENNAL LOBE.}, journal = {J Neurosci}, year = {2020}, month = {2020 Jun 12}, abstract = {

Several features of the adult nervous systems develop in a "critical period," (CP) during which high levels of plasticity allow neural circuits to be tuned for optimal performance. Through an analysis of long-term olfactory habituation (LTH) in female , we provide new insight into mechanisms by which CPs are regulated LTH manifests as a persistently reduced behavioural response to an odorant encountered for four continuous days and occurs together with the growth of specific, odorant-responsive glomeruli in the antennal lobe. We show that the CP for behavioral and structural plasticity induced by ethyl butyrate (EB) or carbon dioxide (CO) closes within 48 hours after eclosion. The elaboration of excitatory projection neuron (PN) processes likely contribute to glomerular volume increases: both occur together and similarly require cAMP signalling in the antennal lobe inhibitory local interneurons (iLNs). Further, the CP for structural plasticity could be extended beyond 48 hours if EB- or CO-responsive olfactory sensory neurons (OSNs) are silenced after eclosion; thus, OSN activity is required for closing the CP. Strikingly, silencing of glomerulus-selective OSNs extends the CP for structural plasticity only in respective target glomeruli. This indicates existence of a local, short-range mechanism for regulating CP closure. Such a local mechanism for CP regulation can explain why plasticity induced by the odorant geranyl acetate (GA, which is attractive) shows no CP although it involves the same core plasticity mechanisms as CO and EB. Local control of critical-period closure mechanisms can potentially impart evolutionarily adaptive, odorant-specific features to behavioral plasticity.The critical period for plasticity represents a stage of life at which animals learn specific tasks or features with particular facility. This work provides fresh evidence that mechanisms for regulating critical periods are broadly conserved across evolution. Thus, a critical period for long-term olfactory habituation in Drosophila which closes early in adulthood can, like the critical period for ocular dominance plasticity in mammals, be extended by blocking sensory neurons early in life. Further observations show that critical periods for plasticity can be regulated by spatially restricted mechanisms, potentially allowing varied critical periods for plasticity to stimuli of different ethological relevance.

}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.2192-19.2020}, author = {Chodankar, Ankita and Sadanandappa, Madhumala K and VijayRaghavan, K and Ramaswami, Mani} } @article {62775, title = {Adult Drosophila muscle morphometry through microCT reveals dynamics during ageing.}, journal = {Open Biol}, volume = {9}, year = {2019}, month = {2019 Jun 28}, pages = {190087}, abstract = {

Indirect flight muscles (IFMs) in adult Drosophila provide the key power stroke for wing beating. They also serve as a valuable model for studying muscle development. An age-dependent decline in Drosophila free flight has been documented, but its relation to gross muscle structure has not yet been explored satisfactorily. Such analyses are impeded by conventional histological preparations and imaging techniques that limit exact morphometry of flight muscles. In this study, we employ microCT scanning on a tissue preparation that retains muscle morphology under homeostatic conditions. Focusing on a subset of IFMs called the dorsal longitudinal muscles (DLMs), we find that DLM volumes increase with age, partially due to the increased separation between myofibrillar fascicles, in a sex-dependent manner. We have uncovered and quantified asymmetry in the size of these muscles on either side of the longitudinal midline. Measurements of this resolution and scale make substantive studies that test the connection between form and function possible. We also demonstrate the application of this method to other insect species making it a valuable tool for histological analysis of insect biodiversity.

}, issn = {2046-2441}, doi = {10.1098/rsob.190087}, author = {Chaturvedi, Dhananjay and Prabhakar, Sunil and Aggarwal, Aman and Atreya, Krishan B and VijayRaghavan, K} } @article {55792, title = {Asrij/OCIAD1 suppresses CSN5-mediated p53 degradation and maintains mouse hematopoietic stem cell quiescence.}, journal = {Blood}, year = {2019}, month = {2019 Apr 05}, abstract = {

Inactivation of the tumor suppressor p53 is essential for unrestrained growth of cancers. However, only 11\% of hematological malignancies have mutant p53. Mechanisms that cause wild type p53 dysfunction and promote leukemia are inadequately deciphered. The stem cell protein Asrij/OCIAD1 is misexpressed in several human hematological malignancies and implicated in the p53 pathway and DNA damage response. However, Asrij function in vertebrate hematopoiesis remains unknown. We generated the first asrij null (knockout, KO) mice and show that they are viable and fertile with no gross abnormalities. However, by six months, they exhibit increased peripheral blood cell counts, splenomegaly and an expansion of bone marrow hematopoietic stem cells (HSCs) with higher myeloid output. HSCs lacking Asrij are less quiescent and more proliferative with higher repopulation potential as observed from serial transplantation studies. However, stressing KO mice with sub-lethal gamma irradiation or multiple injections of 5-fluorouracil results in reduced survival and rapid depletion of hematopoietic stem/progenitor cells (HSPCs) by driving them into proliferative exhaustion. Molecular and biochemical analyses revealed increased polyubiquitinated protein levels, Akt/STAT5 activation and CSN5 (COP9 signalosome subunit 5)-mediated p53 ubiquitination and degradation in KO HSPCs. Further, we show that Asrij sequesters CSN5 via its conserved OCIA domain, thereby preventing p53 degradation. In agreement, Nutlin-3 treatment of KO mice restored p53 levels and reduced high HSPC frequencies. Thus, we provide a new mouse model resembling myeloproliferative disease and identify a post-translational regulator of wild type p53 essential for maintaining HSC quiescence that could be a potential target for pharmacological intervention.

}, issn = {1528-0020}, doi = {10.1182/blood.2019000530}, author = {Sinha, Saloni and Dwivedi, Tirath Raj and Yengkhom, Roja and Bheemsetty, Venkata Anudeep and Abe, Takaya and Kiyonari, Hiroshi and VijayRaghavan, K and Inamdar, Maneesha S} } @article {66853, title = {From a syncytium to mononucleate cells and back: Yki and JNK in symphony.}, journal = {J Cell Biol}, year = {2019}, month = {2019 Oct 25}, abstract = {

Alary muscle syncytia in larvae undergo a remarkable process of dedifferentiation into single cells that then fuse to become ventral longitudinal muscle in the adult. In this issue, Schaub et al. (2019. https://doi.org/10.1083/jcb.201905048) identify the Hippo and JNK signaling pathways as key regulators of this process of developmental remodeling of cell fate.

}, issn = {1540-8140}, doi = {10.1083/jcb.201910025}, author = {Chaturvedi, Dhananjay and VijayRaghavan, K} } @article {64331, title = {Heinrich Reichert (1949-2019).}, journal = {Development}, volume = {146}, year = {2019}, month = {2019 Aug 19}, abstract = {

Heinrich Reichert, Professor Emeritus at the University of Basel, Switzerland, passed away on the 13th of June 2019 after a prolonged illness. Heinrich described himself as {\textquoteright}a hedonist when it came to science{\textquoteright} because he said it gave him great pleasure. It was this quality that made working with Heinrich thrilling and deeply fulfilling. Heinrich{\textquoteright}s long and versatile career spanned the breadth of neuroscience - from development, to evolution and behaviour. In his passing we have lost not just an astute scientist, but also an impassioned educator and an adventurer of science.

}, issn = {1477-9129}, doi = {10.1242/dev.183517}, author = {Sen, Sonia and VijayRaghavan, K} } @article {68514, title = {A locomotor assay reveals deficits in heterozygous Parkinson{\textquoteright}s disease model and proprioceptive mutants in adult .}, journal = {Proc Natl Acad Sci U S A}, year = {2019}, month = {2019 Nov 20}, abstract = {

Severe locomotor impairment is a common phenotype of neurodegenerative disorders such as Parkinson{\textquoteright}s disease (PD). models of PD, studied for more than a decade, have helped in understanding the interaction between various genetic factors, such as and PINK1, in this disease. To characterize locomotor behavioral phenotypes for these genes, fly climbing assays have been widely used. While these simple current assays for locomotor defects in mutants measure some locomotor phenotypes well, it is possible that detection of subtle changes in behavior is important to understand the manifestation of locomotor disorders. We introduce a climbing behavior assay which provides such fine-scale behavioral data and tests this proposition for the model. We use this inexpensive, fully automated assay to quantitatively characterize the climbing behavior at high parametric resolution in 3 contexts. First, we characterize wild-type flies and uncover a hitherto unknown sexual dimorphism in climbing behavior. Second, we study climbing behavior of heterozygous mutants of genes implicated in the fly PD model and reveal previously unreported prominent locomotor defects in some of these heterozygous fly lines. Finally, we study locomotor defects in a homozygous proprioceptory mutation ( ) known to affect fine motor control in Moreover, we identify aberrant geotactic behavior in mutants, thereby opening up a finer assay for geotaxis and its genetic basis. Our assay is therefore a cost-effective, general tool for measuring locomotor behaviors of wild-type and mutant flies in fine detail and can reveal subtle motor defects.

}, issn = {1091-6490}, doi = {10.1073/pnas.1807456116}, author = {Aggarwal, Aman and Reichert, Heinrich and VijayRaghavan, K} } @article {30153, title = {GABAergic inhibition of leg motoneurons is required for normal walking behavior in freely moving.}, journal = {Proc Natl Acad Sci U S A}, year = {2018}, month = {2018 Feb 13}, abstract = {

Walking is a complex rhythmic locomotor behavior generated by sequential and periodical contraction of muscles essential for coordinated control of movements of legs and leg joints. Studies of walking in vertebrates and invertebrates have revealed that premotor neural circuitry generates a basic rhythmic pattern that is sculpted by sensory feedback and ultimately controls the amplitude and phase of the motor output to leg muscles. However, the identity and functional roles of the premotor interneurons that directly control leg motoneuron activity are poorly understood. Here we take advantage of the powerful genetic methodology available into investigate the role of premotor inhibition in walking by genetically suppressing inhibitory input to leg motoneurons. For this, we have developed an algorithm for automated analysis of leg motion to characterize the walking parameters of wild-type flies from high-speed video recordings. Further, we use genetic reagents for targeted RNAi knockdown of inhibitory neurotransmitter receptors in leg motoneurons together with quantitative analysis of resulting changes in leg movement parameters in freely walkingOur findings indicate that targeted down-regulation of the GABAreceptor Rdl (Resistance to Dieldrin) in leg motoneurons results in a dramatic reduction of walking speed and step length without the loss of general leg coordination during locomotion. Genetically restricting the knockdown to the adult stage and subsets of motoneurons yields qualitatively identical results. Taken together, these findings identify GABAergic premotor inhibition of motoneurons as an important determinant of correctly coordinated leg movements and speed of walking in freely behaving.

}, issn = {1091-6490}, doi = {10.1073/pnas.1713869115}, author = {Gowda, Swetha B M and Paranjpe, Pushkar D and Reddy, O Venkateswara and Thiagarajan, Devasena and Palliyil, Sudhir and Reichert, Heinrich and VijayRaghavan, K} } @article {30982, title = {Identification of a Single Pair of Interneurons for Bitter Taste Processing in the Drosophila Brain.}, journal = {Curr Biol}, year = {2018}, month = {2018 Feb 21}, abstract = {

Drosophila has become an excellent model system for investigating the organization and function of the gustatory system due to the relatively simple neuroanatomical organization of its brain and the availability of powerful genetic and transgenic technology. Thus, at the molecular and cellular levels, a great deal of insight into the peripheral detection and coding of gustatory information has already been attained. In contrast, much less is known about the central neural circuits that process this information and induce behaviorally appropriate motor output. Here, we combine functional behavioral tests with targeted transgene expression through specific driver lines to identify a single bilaterally homologous pair of bitter-sensitive interneurons that are located in the subesophageal zone of the brain. Anatomical and functional data indicate that these interneurons receive specific synaptic input from bitter-sensitive gustatory receptor neurons. Targeted transgenic activation and inactivation experiments show that these bitter-sensitive interneurons can largely suppress the proboscis extension reflex to appetitive stimuli, such as sugar and water. These functional experiments, together with calcium-imaging studies and calcium-modulated photoactivatable ratiometric integrator (CaMPARI) labeling, indicate that these first-order local interneurons play an important role in the inhibition of the proboscis extension reflex that occurs in response to bitter tastants. Taken together, our studies present a cellular identification and functional characterization of a key gustatory interneuron in the bitter-sensitive gustatory circuitry of the adult fly.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2018.01.084}, author = {Bohra, Ali Asgar and Kallman, Benjamin R and Reichert, Heinrich and VijayRaghavan, K} } @article {35149, title = {RNP-Granule Assembly via Ataxin-2 Disordered Domains Is Required for Long-Term Memory and Neurodegeneration.}, journal = {Neuron}, volume = {98}, year = {2018}, month = {2018 May 16}, pages = {754-766.e4}, abstract = {

Human Ataxin-2 is implicated in the cause and progression of amyotrophic lateral sclerosis (ALS) and type 2 spinocerebellar ataxia (SCA-2). In Drosophila, a conserved atx2 gene is essential for animal survival as well as for normal RNP-granule assembly, translational control, and long-term habituation. Like its human homolog, Drosophila Ataxin-2 (Atx2) contains polyQ repeats and additional intrinsically disordered regions (IDRs). We demonstrate that Atx2 IDRs, which are capable of mediating liquid-liquid phase transitions in\ vitro, are essential for efficient formation of neuronal mRNP assemblies in\ vivo. Remarkably, ΔIDR mutants that lack neuronal RNP granules show normal animal development, survival, and fertility. However, they show defects in long-term memory formation/consolidation as well as in C9ORF72 dipeptide repeat or FUS-induced neurodegeneration. Together, our findings demonstrate (1) that higher-order mRNP assemblies contribute to long-term neuronal plasticity and memory, and (2) that a targeted reduction in RNP-granule formation efficiency can alleviate specific forms of neurodegeneration.

}, issn = {1097-4199}, doi = {10.1016/j.neuron.2018.04.032}, author = {Bakthavachalu, Baskar and Huelsmeier, Joern and Sudhakaran, Indulekha P and Hillebrand, Jens and Singh, Amanjot and Petrauskas, Arnas and Thiagarajan, Devasena and Sankaranarayanan, M and Mizoue, Laura and Anderson, Eric N and Pandey, Udai Bhan and Ross, Eric and VijayRaghavan, K and Parker, Roy and Ramaswami, Mani} } @article {32474, title = {Rudhira/BCAS3 is essential for mouse development and cardiovascular patterning.}, journal = {Sci Rep}, volume = {8}, year = {2018}, month = {2018 Apr 04}, pages = {5632}, abstract = {

Rudhira/Breast Carcinoma Amplified Sequence 3 (BCAS3) is a cytoskeletal protein that promotes directional cell migration and angiogenesis in vitro and is implicated in human carcinomas and coronary artery disease. To study the role of Rudhira during development in vivo, we generated the first knockout mouse for rudhira and show that Rudhira is essential for mouse development. Rudhira null embryos die at embryonic day (E) 9.5 accompanied by severe vascular patterning defects in embryonic and extra-embryonic tissues. To identify the molecular processes downstream of rudhira, we analyzed the transcriptome of intact knockout yolk sacs. Genome-wide transcriptome analysis showed that Rudhira functions in angiogenesis and its related processes such as cell adhesion, extracellular matrix organization, peptidase activity and TGFβ signaling. Since Rudhira is also expressed in endothelial cells\ (ECs), we further generated Tie2Cre-mediated endothelial knockout (CKO) of rudhira. CKO embryos survive to E11.5 and similar to the global knockout, display gross vascular patterning defects, showing that endothelial Rudhira is vital for development. Further, Rudhira knockdown ECs in culture fail to sprout in a spheroid-sprouting assay, strongly supporting its role in vascular patterning. Our study identifies an essential role for Rudhira in blood vessel remodeling and provides a mouse model for cardiovascular development.

}, issn = {2045-2322}, doi = {10.1038/s41598-018-24014-w}, author = {Shetty, Ronak and Joshi, Divyesh and Jain, Mamta and Vasudevan, Madavan and Paul, Jasper Chrysolite and Bhat, Ganesh and Banerjee, Poulomi and Abe, Takaya and Kiyonari, Hiroshi and VijayRaghavan, K and Inamdar, Maneesha S} } @article {26280, title = {Drosophila adult muscle development and regeneration.}, journal = {Semin Cell Dev Biol}, year = {2017}, month = {2017 Nov 16}, abstract = {

Myogenesis is a highly orchestrated, complex developmental process by which cell lineages that are mesodermal in origin generate differentiated multinucleate muscle cells as a final product. Considerable insight into the process of myogenesis has been obtained for the embryonic development of the larval muscles of Drosophila. More recently, the postembryonic development of the muscles of the adult fly has become a focus of experimental investigation of myogenesis since specific flight muscles of the fly manifest remarkable similarities to vertebrate muscles in their development and organization. In this review, we catalog some of the milestones in the study of myogenesis in the large adult-specific flight muscles of Drosophila. The identification of mesoderm-derived muscle stem cell lineages, the characterization of the symmetric and asymmetric divisions through which they produce adult-specific myoblasts, the multifaceted processes of myoblast fusion, and the unexpected discovery of quiescent satellite cells that can be activated by injury are discussed. Moreover, the finding that all of these processes incorporate a plethora of signaling interactions with other myogenic cells and with niche-like neighboring tissue is considered. Finally, we briefly point out possible future developments in the area of Drosophila myogenesis that may lead to of new avenues of genetic research into the roles of muscle stem cells in development, disease and aging.

}, issn = {1096-3634}, doi = {10.1016/j.semcdb.2017.11.017}, author = {Gunage, Rajesh D and Dhanyasi, Nagaraju and Reichert, Heinrich and VijayRaghavan, K} } @article {25252, title = {Identification and functional characterization of muscle satellite cells in Drosophila.}, journal = {Elife}, volume = {6}, year = {2017}, month = {2017 Oct 26}, abstract = {

Work on genetic model systems such as Drosophila and mouse has shown that the fundamental mechanisms of myogenesis are remarkably similar in vertebrates and invertebrates. Strikingly however, satellite cells, the adult muscle stem cells that are essential for the regeneration of damaged muscles in vertebrates, have not been reported in invertebrates. In this study we show that lineal descendants of muscle stem cells are present in adult muscle of Drosophila as small, unfused cells observed at the surface and in close proximity to the mature muscle fibers. Normally quiescent, following muscle fiber injury, we show that these cells express Zfh1 and engage in Notch-Delta dependent proliferative activity and generate lineal descendant populations, which fuse with the injured muscle fiber. In view of strikingly similar morphological and functional features, we consider these novel cells to be the Drosophila equivalent of vertebrate muscle satellite cells.

}, issn = {2050-084X}, doi = {10.7554/eLife.30107}, author = {Chaturvedi, Dhananjay and Reichert, Heinrich and Gunage, Rajesh D and VijayRaghavan, K} } @article {3606, title = {A genome-wide resource for the analysis of protein localisation in Drosophila.}, journal = {Elife}, volume = {5}, year = {2016}, month = {2016}, abstract = {

The Drosophila genome contains \>13000 protein-coding genes, the majority of which remain poorly investigated. Important reasons include the lack of antibodies or reporter constructs to visualise these proteins. Here, we present a genome-wide fosmid library of 10000 GFP-tagged clones, comprising tagged genes and most of their regulatory information. For 880 tagged proteins, we created transgenic lines, and for a total of 207 lines, we assessed protein expression and localisation in ovaries, embryos, pupae or adults by stainings and live imaging approaches. Importantly, we visualised many proteins at endogenous expression levels and found a large fraction of them localising to subcellular compartments. By applying genetic complementation tests, we estimate that about two-thirds of the tagged proteins are functional. Moreover, these tagged proteins enable interaction proteomics from developing pupae and adult flies. Taken together, this resource will boost systematic analysis of protein expression and localisation in various cellular and developmental contexts.

}, issn = {2050-084X}, doi = {10.7554/eLife.12068}, author = {Sarov, Mihail and Barz, Christiane and Jambor, Helena and Hein, Marco Y and Schmied, Christopher and Suchold, Dana and Stender, Bettina and Janosch, Stephan and Kj, Vinay Vikas and Krishnan, R T and Krishnamoorthy, Aishwarya and Ferreira, Irene Rs and Ejsmont, Radoslaw K and Finkl, Katja and Hasse, Susanne and K{\"a}mpfer, Philipp and Plewka, Nicole and Vinis, Elisabeth and Schloissnig, Siegfried and Knust, Elisabeth and Hartenstein, Volker and Mann, Matthias and Ramaswami, Mani and VijayRaghavan, K and Tomancak, Pavel and Schnorrer, Frank} } @article {3571, title = {Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking.}, journal = {Elife}, volume = {5}, year = {2016}, month = {2016}, abstract = {

Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here, we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map.

}, issn = {2050-084X}, doi = {10.7554/eLife.11572}, author = {Syed, Durafshan Sakeena and Gowda, Swetha B M and Reddy, O Venkateswara and Reichert, Heinrich and VijayRaghavan, K} } @article {11606, title = {The Glide/Gcm fate determinant controls initiation of collective cell migration by regulating Frazzled.}, journal = {Elife}, volume = {5}, year = {2016}, month = {2016 Oct 14}, abstract = {

Collective migration is a complex process that contributes to build precise tissue and organ architecture. Several molecules implicated in cell interactions also control collective migration, but their precise role and the finely tuned expression that orchestrates this complex developmental process are poorly understood. Here, we show that the timely and threshold expression of the Netrin receptor Frazzled triggers the initiation of glia migration in the developing Drosophila wing. Frazzled expression is induced by the transcription factor Glide/Gcm in a dose-dependent manner. Thus, the glial determinant also regulates the efficiency of collective migration. NetrinB but not NetrinA serves as a chemoattractant and Unc5 contributes as a repellant Netrin receptor for glia migration. Our model includes strict spatial localization of a ligand, a cell autonomously acting receptor and a fate determinant that act coordinately to direct glia toward their final destination.

}, issn = {2050-084X}, doi = {10.7554/eLife.15983}, author = {Gupta, Tripti and Kumar, Arun and Cattenoz, Pierre B and VijayRaghavan, K and Giangrande, Angela} } @article {3541, title = {Rational elicitation of cold-sensitive phenotypes.}, journal = {Proc Natl Acad Sci U S A}, volume = {113}, year = {2016}, month = {2016 May 3}, pages = {E2506-15}, abstract = {

Cold-sensitive phenotypes have helped us understand macromolecular assembly and biological phenomena, yet few attempts have been made to understand the basis of cold sensitivity or to elicit it by design. We report a method for rational design of cold-sensitive phenotypes. The method involves generation of partial loss-of-function mutants, at either buried or functional sites, coupled with selective overexpression strategies. The only essential input is amino acid sequence, although available structural information can be used as well. The method has been used to elicit cold-sensitive mutants of a variety of proteins, both monomeric and dimeric, and in multiple organisms, namely Escherichia coli, Saccharomyces cerevisiae, and Drosophila melanogaster This simple, yet effective technique of inducing cold sensitivity eliminates the need for complex mutations and provides a plausible molecular mechanism for eliciting cold-sensitive phenotypes.

}, issn = {1091-6490}, doi = {10.1073/pnas.1604190113}, author = {Baliga, Chetana and Majhi, Sandipan and Mondal, Kajari and Bhattacharjee, Antara and VijayRaghavan, K and Varadarajan, Raghavan} } @article {1044, title = {Surface apposition and multiple cell contacts promote myoblast fusion in Drosophila flight muscles.}, journal = {J Cell Biol}, volume = {211}, year = {2015}, month = {2015 Oct 12}, pages = {191-203}, abstract = {

Fusion of individual myoblasts to form multinucleated myofibers constitutes a widely conserved program for growth of the somatic musculature. We have used electron microscopy methods to study this key form of cell-cell fusion during development of the indirect flight muscles (IFMs) of Drosophila melanogaster. We find that IFM myoblast-myotube fusion proceeds in a stepwise fashion and is governed by apparent cross talk between transmembrane and cytoskeletal elements. Our analysis suggests that cell adhesion is necessary for bringing myoblasts to within a minimal distance from the myotubes. The branched actin polymerization machinery acts subsequently to promote tight apposition between the surfaces of the two cell types and formation of multiple sites of cell-cell contact, giving rise to nascent fusion pores whose expansion establishes full cytoplasmic continuity. Given the conserved features of IFM myogenesis, this sequence of cell interactions and membrane events and the mechanistic significance of cell adhesion elements and the actin-based cytoskeleton are likely to represent general principles of the myoblast fusion process.

}, issn = {1540-8140}, doi = {10.1083/jcb.201503005}, author = {Dhanyasi, Nagaraju and Segal, Dagan and Shimoni, Eyal and Shinder, Vera and Shilo, Ben-Zion and VijayRaghavan, K and Schejter, Eyal D} }