Katz, Menachem et al. (2015) International Worm Meeting "Glia control locomotion and sleep in C. elegans."

Iwanir, Shachar, Shaham, Shai, Biron, David, Katz, Menachem, Dragomir, Elena, Corson, Francis

[International Worm Meeting, 2015]

Glia are abundant components of the nervous system, yet their contributions to neural circuits and animal behavior are poorly characterized. To study these contributions, we ablated the astrocyte-like CEPsh glia that ensheath synapses in the C. elegans nerve ring. We find that ablation results in enhanced locomotory quiescence preceding molting-associated lethargy (a sleep-like state), and molting-independent short-duration locomotory pausing. Synapses between the neuron ALA, which governs sleep-like behavior, and the locomotory interneuron AVE are ensheathed by CEPsh glia. Loss of ALA function suppress both precocious lethargus and locomotory pausing, suggesting that CEPsh blocks a locomotion-inhibiting signal from ALA. Several observations suggest this inhibition occurs at the ALA-AVE synapses. Inactivation of AVE promotes locomotory pausing independently of ALA or CEPsh glia states, suggesting it acts downstream of these two cells. In addition, CEPsh glia ablation results in prolonged calcium transients in AVE, which are rescued by ALA inactivation. Finally, AVE calcium levels normally correlate with backwards locomotion; in CEPsh-ablated animals, calcium induction in AVE is uncoupled from movement, and coupling is restored by ALA inactivation. These results suggest that CEPsh glia are essential for the functions of ALA-AVE synapses. To understand how CEPsh glia control synaptic activity, we developed a robust method for isolating these cells from larvae, and generated a list of CEPsh glia-enriched genes using RNAseq. RNAi studies have uncovered potential roles for some enriched genes in locomotion control. CEPsh glia also ensheath the outer aspect of the nerve ring, where they are in close proximity to glutamatergic synapses. Studies in other labs showed that glutamatergic signaling levels correlate with reversal frequency. We found that CEPsh-disrupted animals have an increased reversal frequency, suggesting accumulation of glutamate at synapses. Analysis of the CEPsh transcriptome revealed enriched expression of glt-1, a homolog of the astrocytic glutamate clearance transporter (EAAT2). glt-1 mutants were previously shown to have increased reversal frequency, and we found that expression of glt-1 in CEPsh glia rescues this defect. Together, our studies establish functional and molecular homology between CEPsh glia and vertebrate astrocytes, and identify exciting roles for these cells in locomotory control in C. elegans.

Katz, Menachem et al. (2009) International Worm Meeting "CEP-sheath glia are required for normal locomotion in C. elegans."

Katz, Menachem, Lu, Yun, Shaham, Shai

[International Worm Meeting, 2009]

C. elegans glial cells share morphological, functional and genetic resemblance to their vertebrate counterparts. However, in contrast to vertebrate glia, C. elegans glia are not essential for neuronal survival, offering a unique opportunity to study the involvement of glia in the development and function of the nervous system in vivo. C. elegans CEP sheath glia (CEPsh) are bipolar cells that ensheath the dendrites of CEP neurons, and also envelope the nerve ring (the animal''s brain) extending processes that abut synapses. During development, these cells are involved in regulating axon guidance, dendrite extension, formation of the nerve ring (Yoshimura et al., 2008), and synaptogenesis (Colon-Ramos et al., 2007). However, post-developmental roles for CEPsh glia have not been studied. Here we demonstrate that animals in which the CEPsh glia were genetically ablated during the first larva stage display various motor defects including reduced speed of locomotion and intermittent periods of extended paralysis. Ablated animals also display high levels of small-angle turning, resulting in a spiral pattern of movement that restricts their movement to small areas on the plate. EM analyses of CEPsh glia-ablated animals reveal disorganization of the nerve ring, and swelling of neurons in the ventral ganglion. Thus CEPsh glia may play key homeostatic roles in the neuropil. To understand the molecular basis of CEPsh glia function we have begun to identify genes expressed in these cells using an mRNA-tagging method, with the aim of examining the roles of enriched genes in C. elegans locomotory behavior.

Katz, Menachem et al. (2013) International Worm Meeting "CEPsh glia modulate a sleep-related neuronal circuit in C. elegans."

Dragomir, Elena, Biron, David, Iwanir, Shachar, Corson, Francis, Shaham, Shai, Katz, Menachem

[International Worm Meeting, 2013]

Glia are essential components of the nervous system. However, their precise roles in the regulation of neuronal circuit activities and animal behavior are poorly understood. In 1895, Ramon y Cajal postulated that astrocytes regulate the transition between sleep and waking states. Remarkably, recent studies in mice and flies hint that Cajal's ideas may be more than theoretical musings. Yet, the mechanisms by which glia influence sleep are not fully resolved. Sleep in C. elegans is defined by behavioral lethargy that coincides with molting, linking development and locomotion. The CEPsh glia, which envelope the C. elegans nerve ring, are reminiscent of astrocytes, and extend processes that abut specific nerve-ring synapses. L1 ablation of CEPsh glia results in molting-independent short duration locomotory pausing, episodes of longer immobility immediately preceding molting, and developmental delay. The ALA neuron was previously implicated in sleep control. Interestingly, synapses between ALA and the backward command interneuron AVE are ensheathed by CEPsh glia, suggesting functional roles for these glia in modulating ALA-AVE synaptic activity. Indeed, loss of ALA function suppresses the locomotory defects, developmental delay, and precocious lethargus of CEPsh glia-ablated animals. Furthermore, inactivation of AVE in adults induces pausing reminiscent of CEPsh ablation. In animals lacking CEPsh glia, the duration of spontaneous calcium transients in AVE is prolonged and calcium spikes are decorrelated from backward locomotion. Correlation is restored upon ALA inactivation. These results as well as our functional epistasis studies of ALA, AVE and CEPsh glia are consistent with a model in which glia attenuate a sleep-promoting inhibitory connection between ALA and AVE. We propose that glia play key roles in C. elegans sleep control and that this role may be conserved.

Katz, Menachem et al. (2011) International Worm Meeting "C. elegans locomotory pattern, pausing frequency and speed is regulated by the CEP sheath glia."

Corson, Francis, Shaham, Shai, Katz, Menachem

[International Worm Meeting, 2011]

Neuronal circuits are tightly regulated to achieve proper animal behavior. Recent studies suggest that glial cells can influence neuronal functions and synaptic activities, and may, thus, contribute to behavior. However, the precise contributions of synaptic glia to animal behavior are poorly understood. C. elegans glia share morphological, functional, and genetic features with their vertebrate counterparts. However, in contrast to vertebrate glia, C. elegans glia are not essential for neuronal survival, offering a unique arena for exploring the involvement of glia in neuronal functions in a live animal. The CEP sheath glia (CEPsh) are bipolar cells that ensheath the dendrites of CEP neurons, and envelope the nerve ring. Reminiscent of mammalian astrocytes, these cells extend processes that abut specific synapses within the nerve ring. We showed that ablation of the CEPsh glia during the first larval stage results in abnormal locomotory behavior. CEPsh-ablated animals display reduced locomotion speed and extended locomotory pausing, as well as exaggerated small-angle turns and frequent reversals that limit their dispersal. To understand how these behaviors are regulated by CEPsh glia, we focused on the ALA-AVE synapse ensheathed by these glia (White et al., 1986). In line with the previously described role of ALA in behavioral quiescence and locomotory pausing (Van Buskirk and Sternberg, 2008), we found that inactivation of ALA reduces the pausing frequencies of glia-ablated animals. In addition, the dispersal of these animals and their speed of locomotion are improved. Inactivation of AVE in wild-type animals, induces extended pausing periods comparable to those seen in glia ablated animals, and animal speed is reduced. Our results suggest that AVE is a key regulator of speed and pausing frequency in the C. elegans nervous system, and that ALA functions to inhibit the activity of AVE. Moreover, our results indicate that the CEPsh glia provide important negative regulation on the activity of this tripartite synapse. To understand the molecular basis of CEPsh glia function we have begun to identify genes expressed in these cells using an RNA-tagging method, with the aim of examining the roles of enriched genes in C. elegans locomotory behavior.

Katz, Menachem et al. (2017) International Worm Meeting "Repetitive behavior mediated by glutamate is controlled by astrocyte-like glia in C. elegans."

Keil, Wolfgang, Katz, Menachem, Singhal, Anupriya, Shaham, Shai, Liang, Yupu, Corson, Francis, Bae, Andrea, Lu, Yun

[International Worm Meeting, 2017]

Neural circuits control animal behavior, and their dysfunction promotes neurological diseases manifesting aberrant behaviors. Neural circuits are tightly associated with astroglial processes, yet glial roles in animal behavior are not well understood. C. elegans has a compact nervous system driving a limited and well-characterized behavioral repertoire. C. elegans glia are not essential for neuron viability, making this animal a useful setting for investigating glial influences on circuits and behavior. We have characterized roles of the brain-associated C. elegans CEPsh glia in animal locomotion. We demonstrate that, like astrocytes, CEPsh glia infiltrate the brain neuropil and abut glutamatergic synapses. Postembryonic ablation of CEPsh glia results in foraging defects, including an increased reversal rate. CEPsh glia transcriptome analysis reveals similarities to astrocytes, including expression of the glial glutamate transporter, glt-1. Behavior studies reveal that glt-1 mutants, unlike wild-type animals, have increased reversal frequency, as well as repetitive reversal bouts. AVA neurons control reversal initiation, and our in vivo measurements of synaptic glutamate adjacent to AVA reveal roles for glial GLT-1 in rapid glutamate clearance. Inappropriate clearance leads to high-frequencies oscillations in synaptic glutamate and AVA activation. We show that these oscillations are mediated by the presynaptic metabotropic glutamate receptor mgl-2/mGluR5, and that mutations in mgl-2 suppress glt-1-mediated repetitive reversals. Loss of murine astrocyte-expressed GLT1 has been shown to produce repetitive grooming, and inhibition of murine mGluR5 ameliorates repetitive behavior in an Obsessive Compulsive Disease (OCD) model. Our studies, therefore, suggest conserved roles for glutamate clearance by glia in controlling repetitive behavior, a feature of some human neuropsychiatric disorders.

Menachem Katz et al. (2008) C.elegans Neuronal Development Meeting "Glial Control of Neuronal Function in C. elegans"

Yun Lu, Menachem Katz, Shai Shaham

[C.elegans Neuronal Development Meeting, 2008]

C. elegans glial cells share morphological, functional and genetic resemblance to their vertebrate counterparts. However, in contrast to vertebrate glia, C. elegans glia are not essential for neuronal survival, offering a unique opportunity to study the involvement of glia in the development and function of the nervous system in vivo. C. elegans CEP sheath glia (CEPsh) are bipolar cells that ensheath the dendrites of CEP neurons, and also envelope the nerve ring (the animal''s brain) extending processes that abut synapses. During development, these cells are involved in regulating axon guidance, dendrite extension and the formation of the nerve ring (Yoshimura et al., submitted). However, post-developmental roles for CEPsh glia have not been studied. Here we demonstrate that animals in which the CEPsh glia were genetically ablated during the first larva stage display uncoordinated movement. Interestingly, delayed development is also observed in these glia-ablated animals. EM analyses of CEPsh glia-ablated animals reveal disorganization of the nerve ring, and swelling of neurons within the ventral ganglia. Thus CEPsh glia play key roles in regulating neuronal function. To understand the molecular basis of CEPsh glia function we plan to identify genes expressed in these cells using a ribosome-tagging method, and to define contributions of these genes to glial function. We also plan to pursue studies aimed at testing whether CEPsh glia may serve as a permeability barrier akin to the blood-brain barrier.

Swigut T et al. (2009) Cell "Fallen immortals."

Wysocka J, Swigut T

[Cell, 2009]

The memory of somatic cell gene expression is reset in the germline in a process that is accompanied by dramatic changes in chromatin modifications. In this issue, Katz et al. (2009) show that the histone demethylase Lsd1/Spr-5 may participate in this resetting process in the worm, thereby preventing a decline in germ cell epigenetic stability and viability over ensuing generations.

(2021) Development "The people behind the papers - Brandon Carpenter and David Katz."

[Development, 2021]

A dynamic pattern of histone methylation and demethylation controls gene expression during development, with some processes such as formation of the zygote involving large-scale reprogramming of methylation states. A new paper in Development investigates how inherited histone methylation regulates developmental timing and the germline/soma distinction in <i>Caenorhabditis elegans</i> To hear more about the story we caught up with first author and postdoctoral researcher Brandon Carpenter, and his supervisor David Katz, Associate Professor in the Department of Cell Biology at Emory University School of Medicine in Atlanta, Georgia.

Takao Inoue et al. (2002) West Coast Worm Meeting "lin-17, lin-18 and patterning of the P7.p lineage"

Rashmi Deshpande, Paul W Sternberg, Russell Hill, Takao Inoue

[West Coast Worm Meeting, 2002]

We are interested in patterning of the 2 (secondary) vulval lineages P5.p and P7.p. In the wild-type, P5.p and P7.p produce stereotyped ABCD and DCBA patterns respectively. In lin-17 and lin-18 mutants, the polarity of the P7.p lineage becomes altered. We examined the P7.p lineage in lin-17 (encoding Frizzled Wnt receptor), lin-18 (encoding RYK receptor tyrosine kinase-related protein; W. Katz and P.W.S.), and double mutant using POP-1 (TCF/LEF) antibody staining and cell fate markers ceh-2::yfp and cdh-3::cfp.

Katz, David et al. (2021) International Worm Meeting "The Pipeline CURE: lowering institutional barriers to research by reiteratively incorporating original C. elegans experiments throughout a biology curriculum"

Lee, Teresa, Schmeichel, Karen, Katz, David, Carpenter, Brandon

[International Worm Meeting, 2021]

Participation in research provides personal and professional benefits for undergraduates. However, some students face institutional barriers that prevent their entry into research, particularly those from underrepresented groups who may stand to gain the most from research experiences. Course-based undergraduate research experiences (CUREs) effectively scale research availability, but many only last for a single semester, which is rarely enough time for a novice to develop proficiency. To address these challenges, we established a Pipeline CURE. The Pipeline CURE integrates C. elegans epigenetics research being conducted by the Katz Lab at Emory University throughout the biology curriculum at Oglethorpe University, a nearby liberal arts college. Students are introduced to C. elegans with their first course in the major. After revisiting the research system in several subsequent courses, students can choose to participate in an upper-level research experience, led by an NIH Institutional Research and Academic Career Development Award (IRACDA) postdoctoral fellow from the Katz Lab. Preliminary data taken during implementation of The Pipeline CURE suggests that the reiterative CURE strategy can recapitulate benefits of a traditional apprenticeship lab experience entirely within the curriculum in a classroom setting. These benefits associated with The Pipeline Cure include including replacing beginner confidence with mastery and resilience via repeated exposure to the same research system. As a result, the Pipeline CURE levels the playing field by giving underrepresented students the chance to experience original research, and potentially conduct honors thesis research, without having to seek out a traditional apprenticeship lab experience. The research experience gained by students can serve as an entry to STEM careers, or provide a platform for competing for admission to graduate programs. In addition, the data generated can open new areas of research and help facilitate publication of manuscripts. As an added benefit, The Pipeline CURE also exposes postdoctoral fellows to challenges that underrepresented groups face in the classroom. Thus, by uniting evidence-based teaching methods with ongoing scientific research, the Pipeline CURE provides a new model for overcoming barriers to participation in undergraduate research, that is flexible enough to be implemented at a range of institutions using a variety of research questions.