224A Mudd Hall
Department of Biology
Johns Hopkins University
3400 N. Charles Street
Baltimore, MD 21218-2685
Office 410 516-2366
Lab 410 516-7641
Departmental fax 410 516-5213
B.S.Calcutta University, India
Ph.D.University of Houston, Texas, USA
PostdoctoralJohns Hopkins University - School of Medicine, USA
Research InterestsThe proper functioning of the nervous system relies on the establishment of precise neuronal circuits. These neuronal circuits are largely formed during early development. To form functional neuronal circuits, neurons receive specific information in the form of extracellular cues from the target tissues that they innervate. To date, the family of neurotrophins provides the best example of these target-derived instructive cues that regulate diverse developmental events in the vertebrate nervous system, including survival, axonal and dendritic growth and synapse formation. Using a combination of cell biological, biochemical and imaging techniques as well as mouse genetics, we are actively pursuing two lines of research:
- How neurotrophic factors coordinate neuronal development by regulating the neuronal endocytic machinery, and
- Growth factor signaling pathways underlying axonal growth, morphology and innervation of target tissues during development.
Figure 1. Regulated trafficking of TrkA receptors. Target-derived NGF promotes neuronal survival by retrograde trafficking of TrkA receptors in signaling endosomes from axon terminals to cell bodies. NGF also recruits TrkA receptors to axon terminals by endocytic removal of mature receptors from cell body surfaces and vesicular transport via recycling endosomes. From Ascano et. al., J. Neuroscience 2009
Regulation of neuronal development by trafficking of neurotrophins and their receptors:
For decades, it has been known that neurotrophins and their receptors undergo long-range trafficking in neurons, but how neurotrophins utilize the trafficking machinery to regulate distinct aspects of neuronal development remains poorly characterized.
Recently, we showed that the target-derived neurotrophin, nerve growth factor (NGF) regulates a local calcineurin-mediated endocytic pathway in axons to promote axon growth in sympathetic neurons (Bodmer et. al, 2011). Calcineurin is a calcium-responsive phosphatase that is highly enriched in the nervous system. Previously, calcineurin-controlled transcriptional programs were shown to be critical for neural development. We found that calcineurin-mediated dephosphorylation of the endocytic GTPase, dynamin1, is specifically required for NGF-mediated innervation of target tissues but dispensable for initial axonal outgrowth. By identifying specific calcineurin-interacting dynamin1 isoforms that promote NGF receptor endocytosis and axonal growth, our study also provided evidence of functional relevance of dynamin1 splicing in nervous system development.
NGF also controls axon growth by promoting long-range vesicular trafficking of its TrkA receptors, in addition to local endocytic events within axon terminals. We found that target-derived NGF regulates the anterograde delivery of TrkA receptors via an unusual endocytosis-based trafficking pathway called transcytosis (Ascano et. al, 2009). Mature Trk receptors on neuronal cell bodies are endocytically removed and re-targeted to axons through Rab11-positive recycling endosomes. Perturbing endocytic recycling attenuated NGF-dependent axon growth, while enhancing recycling increased neuronal sensitivity to limiting concentrations of NGF. Endocytic trafficking of TrkA receptors has been best-studied in the context of NGF-dependent neuronal survival. Our findings provided the first evidence that endocytic events are not only critical for neurotrophin-mediated survival but also for the regulation of axon growth.
Our long-term goal is to gain insight into how neurotrophins coordinate neuronal development by regulating the cell’s endocytic machinery. Using a combination of fluorescent, biochemical and electron microscopic assays, we are currently investigating molecular mechanisms of endocytosis, recycling and long-distance axonal transport of neurotrophins and their receptors in developing neurons.
Figure 2. Autocrine Wnt5a signaling in sympathetic neurons is necessary for sympathetic axon branching. TH-Cre;Wnt5afl/fl embryos show deficits in sympathetic innervation of salivary glands compared to control TH-Cre;Wnt5afl/fl animals. Whole mount TH staining shows that sympathetic fibers fail to extend and arborize in the salivary glands at embryonic day 16.5 (E16.5). From Ryu et. al, Developmental Biology, 2013
Sympathetic innervation of peripheral targets is coordinated by target-derived neurotrophins and neuronal Wnts
One mechanism by which a limited number of neurotrophins could elicit a broad spectrum of biological effects is through their interactions with other growth factor signaling pathways. We found that Wnt5a, a member of the Wnt family of embryonic morphogens, is produced in sympathetic neurons where it promotes axon branching (Bodmer et. al, 2009). Wnt5a levels are enhanced by NGF, revealing an unexpected hierarchical pathway of growth factor signaling; retrograde signaling by target-derived NGF promotes Wnt5a expression in sympathetic neurons, and secretion of Wnt5a, in turn, exerts an autocrine effect on sympathetic axons. Using tissue-specific deletion of Wnt5a, we showed that Wnt5a derived from sympathetic neurons is required for their target innervation in vivo (Ryu et. al, 2013). This suggests a new regulatory mechanism to instruct target innervation, whereby in-growing axons themselves produce diffusible cues dependent on signals derived from the target.
The identification of an autocrine Wnt5a signaling mechanism in the terminal arborization of sympathetic axons is a critical step toward understanding the molecular cues that control distinct aspects of sympathetic innervation. We are currently investigating tissue-specific and temporal roles of Wnt5a signaling in the developing and adult nervous system as well as identifying the downstream targets of Wnt5a signaling.
Figure 3. Sympathetic innervation of mouse pancreatic islets. The image shows the close association between sympathetic fibers (stained for tyrosine hydroxylase in green) and vasculature (stained with wheat germ agglutinin in blue) with developing islets (stained for insulin in red). The image also shows tyrosine hydroxylase-positive beta-cells that are found within islets.
Role of sympathetic innervation in pancreas development
The sympathetic nervous system develops in parallel with the organogenesis of innervated peripheral tissues. It is well established that, during development, sympathetic neurons rely on target-derived signals for survival and growth. However, surprisingly little is known about the reciprocal contribution of sympathetic innervation to the morphogenesis of a target tissue. Pancreatic islets of Langerhans, the functional units in the regulation of glucose homeostasis, are richly innervated by sympathetic fibers. While neural activity is known to modulate hormone release in adult islets, the contribution of sympathetic innervation to pancreatic organogenesis remains unknown. We recently found that sympathetic innervation is necessary for the formation of the pancreatic islets of Langerhans and for their functional maturation (Borden et. al, in press). Genetic or pharmacological ablation of sympathetic innervation during development resulted in altered islet architecture, reduced insulin secretion and impaired glucose tolerance in mice. Similar defects were observed with pharmacological blockade of β-adrenergic signaling. Conversely, the administration of a β-adrenergic agonist restored islet morphology and glucose tolerance in de-innervated animals. Furthermore, in neuron-islet co-cultures, sympathetic neurons promoted islet cell migration in a β-adrenergic dependent manner. Our study reveals that islet architecture requires extrinsic inductive cues from neighboring tissues such as sympathetic nerves, and suggests that early perturbations in sympathetic innervation might underlie metabolic disorders.
The immediate directions for this project are to identify the nerve-derived signals and characterize the signaling pathways activated in islet cells that regulate islet structure and acquisition of functional maturation. These studies will provide new insight into islet development, and will have important implications for current translational efforts to identify factors critical for the onset of pancreatic dysfunction.
Philip Borden, Jessica Houtz, Steven D. Leach, Rejji Kuruvilla. Sympathetic innervation during development is necessary for pancreatic islet architecture and functional maturation. Cell Reports, in press.
Oscar Marcelo Lazo, Andres Gonzalez, Maria Ascano, Rejji Kuruvilla, Andres Couve, and Francisca Bronfman. BDNF regulates Rab11-mediated recycling endosome dynamics to induce dendritic branching. J. Neuroscience. 2013. Apr 3;33(14):6112-22
Shih-Kuo Chen, Kylie S. Chew, David S. McNeill, Patrick W. Keeley, Jennifer L. Ecker, Buqing Q. Mao, Johan Pahlberg, Bright Kim,
Sammy C.S. Lee, Michael Fox, William Guido, Kwoon Y. Wong, Alapakkam P. Sampath, Benjamin E. Reese, Rejji Kuruvilla,* and Samer Hattar*.
Apoptosis regulates ipRGC spacing necessary for rods and cones to drive circadian photoentrainment.
Neuron. 2013 Feb 6;77(3):503-15.
Yun Kyoung Ryu, King Yu Lo, Sarah Collins, Haiqing Zhao* and Rejji Kuruvilla*.
An autocrine Wnt5a-Ror signaling loop mediates sympathetic target innervation.
Developmental Biology. 2013 Feb 27.
Henry Ho, Michael Susman, Jay Bikoff, Yun Kyoung Ryu, Andrea Jonas, Linda Hu, Rejji Kuruvilla and Michael E. Greenberg. Wnt5a-Ror-Dishevelled signaling constitutes a core developmental pathway that controls tissue morphogenesis. Proc Natl Acad Sci U S A. 2012 Mar 13;109(11):4044-51. Epub 2012 Feb 17
Maria Ascano, Daniel Bodmer and Rejji Kuruvilla. Endocytic trafficking of neurotrophins in neural development. Trends Cell Biol. 2012 Mar 21. [Epub ahead of print]
Daniel Bodmer*, Maria Ascaño* and Rejji Kuruvilla, 2011.
Isoform-specific dephosphorylation of dynamin1 by calcineurin couples neurotrophin receptor
endocytosis to axonal growth.
Neuron 70, 1085-1099.
* Equal authors.
Alissa Armstrong, Yun Kyoung Ryu, Deanna Chieco and Rejji Kuruvilla. 2011. Frizzled3 is required for neurogenesis and target innervation during sympathetic nervous system development. J. Neuroscience 31 (7):2371–2381
Ascaño, M., Richmond, A., Borden, P., and Kuruvilla, R.. 2009. Axonal Targeting of Trk Receptors via Transcytosis Regulates Sensitivity to Neurotrophin Responses. J. Neuroscience 29:11674-11685
Daniel Bodmer, Seamus Levine-Wilkinson, Alissa Richmond, Sarah Hirsh and Rejji Kuruvilla, 2009. Wnt5a mediates NGF-dependent axonal branching and growth in developing sympathetic neurons. J. Neuroscience 29 (23):7569-7581
Larry S. Zweifel, Rejji Kuruvilla, and David D. Ginty, 2005. Functions and Mechanisms of Retrograde Neurotrophin Signaling. Nature Reviews Neuroscience 6, 615-625.
Gregorio Valdez, Wendy Akmentin, Polyxeni Philippidou, Rejji Kuruvilla, David D. Ginty and Simon Halegoua, 2005. Pincher-mediated macroendocytosis underlies retrograde signaling by neurotrophin receptors. J. Neuroscience 25 (21), 5236-5247.
Chen, X., Haihong, Y., Kuruvilla R., Ramanan, N., Scangos, K.W., Zhan, C., Nicolas M. Johnson, N.M., Pamela M. England, Kevan M. Shokat and David D. Ginty. 2005. A chemical–genetic approach to studying neurotrophin signaling. Neuron 46, 13-21.
Rejji Kuruvilla * , Larry Zweifel * , Natalia Glebova, Bonnie Lonze, Haihong Ye and David Ginty. 2004.
A neurotrophin signaling cascade coordinates sympathetic neuron development through differential control
of TrkA trafficking and retrograde signaling.
Cell 118, 1-20.
* Equal authors.
Haihong Ye * , Rejji Kuruvilla * , Larry Zweifel and David Ginty. 2003.
Evidence in support of signaling
endosome-based retrograde survival of sympathetic neurons.
Neuron 39, 57-68.
* Equal authors.
Cristinel Miinea, Rejji Kuruvilla, Houra Merrikh and Joseph Eichberg. 2002. Altered arachidonic acid biosynthesis and antioxidant protection mechanisms in Schwann cells grown in elevated glucose. J. Neurochem. 81:1253-1262.
Rejji Kuruvilla, Haihong Ye and David Ginty. 2000. Spatially and functionally distinct roles of the PI3-K effector pathway during NGF signaling in sympathetic neurons. Neuron 27:499-512.
Rejji Kuruvilla and Joseph Eichberg. 1998. Depletion of phospholipid arachidonoyl-containing molecular species in a human Schwann cell line grown in elevated glucose and their restoration by an aldose reductase inhibitor. J. Neurochem. 71:775-783.