Chang Hoon Jee

University of Tennessee Health Science Center; Memphis TN, United States of America

Changhoon Jee

Gwangju Institute of Science and Technology; Gwangju, South Korea

Jee, Changhoon et al. (2013) International Worm Meeting "Regulation of motivational states in C. elegans."

Jee, Changhoon, Garcia, L. Rene

[International Worm Meeting, 2013]

Motivation is a goal directed driving force based on physiological needs such as hunger, thirst, and sexual arousal. Pathological neuroadaptive changes in brain reward and stress system direct normal motivated behaviors into compulsive behaviors such as binge eating, obsessive drug seeking, and sexual behavior. To further understand how stress molecularly modulates the motivated behavioral state, we studied sex-specific mating behavior of C. elegans. The male mating behavior of C. elegans is a motivated behavior and is modulated by stress. For example, mating potency declines in aging wild-type old males and food deprivation stress during early adulthood leads to neuroadaptive changes, resulting in maintaining sexual potency in older animals. We developed the mating interference assay to quantify the motivational states. The wild-type male mating behavior is interfered by blue light, which is noxious stimulus to worm in dose-dependent manner. We also quantified the motivational states of seb-3 mutant animals, which is CRF receptor-like GPCR, in C. elegans that is a key mediator in stress response. Interestingly, seb-3 (gf) mutants exhibited enhanced motivational states whereas seb-3 (lf) mutant animals showed decreased motivational states, suggesting activation of SEB-3 induces behavioral arousal and leads to powerful motivation. We are currently pursuing an answer of where and how SEB-3 regulates cellular excitability of behavioral circuit components.

Jee, Changhoon et al. (2015) International Worm Meeting "Activation of SEB-3 in LUA interneurons potentiates male mating drive of C. elegans."

Garcia, L. Rene, LeBoeuf, Brigitte, Jee, Changhoon

[International Worm Meeting, 2015]

The male C. elegans' sexual drive intensity determines his reproductive success under stressful conditions. To measure the strength of the male's sexual motivation, we developed the Mating Interference assay (Mi), which quantifies copulation persistence in noxious 475 nm (blue) light. Between copulations, free moving male will escape from 370-450mW/mm2 blue light illumination. However we found that the activated corticotropin-releasing factor (CRF) receptor homolog, SEB-3, causes the gender-common LUA interneurons to potentiate downstream male-specific reproduction circuits. This allows the male's copulatory behaviors to override the light-elicited escape response. SEB-3 also potentiates copulation in standard stress conditions, such as starvation and increased temperatures; thus we suggest that animals use the CRF receptor to acclimate and execute innate behaviors under non-optimal conditions.

Jee, Changhoon et al. (2011) International Worm Meeting "CRF receptor-like GPCR mediated stress response and regulates behavioral states in C. elegans."

Lee, Jungsoo, Garcia, L. Rene, Jee, Changhoon, McIntire, Steven

[International Worm Meeting, 2011]

Motivation is a goal directed driving force based on physiological needs such as hunger, sexual arousal and drug craving. Neuroadaptive changes in brain reward and stress system of animals leads to compulsive behaviors such as binge eating, obsessive drug seeking and sexual behavior. Repeated consumptions of drug leads to neuroadaptive changes to balance the effect of it resulted in tolerance and withdrawal symptom. We isolated SEB-3, CRF receptor-like GPCR, in C. elegans that is a key mediator in stress response. Activation of brain stress system induces behavioral arousal and development of negative reinforcement mechanism that leads to powerful motivation. We found that CRF signaling positively regulates stress response that leads to enhanced active state of locomotion, behavioral arousal and alcohol tolerance and withdrawal behavior in C. elegans. To further understand how seb-3 molecularly regulates the motivated behavioral state, we studied sex-specific mating behavior of C. elegans. The seb-3 is expressed mainly in nervous system and male sex muscles. Normally, mating potency declines in aging wild-type old males and food deprivation stress during early adulthood leads to neuroadaptive changes resulting in maintaining potency in older animals. Interestingly, food deprivation could not enhance mating potency in aging seb-3 (lf) mutant animals. Additionally, we found that seb-3 (gf) enhanced potency in old males without food deprivation and did not increase life span, suggesting that CRF signaling mediates maintaining male mating behavior of old male after food deprivation in C. elegans. We are currently pursuing an answer of where and how SEB-3 regulates cellular excitability of behavioral circuit components.

Changhoon Jee et al. (2004) West Coast Worm Meeting "Identification and characterization of calcineurin binding protein in C. elegans."

Changhoon Jee, Joohong Ahnn

[West Coast Worm Meeting, 2004]

Calcineurin is a Ca 2+ /calmodulin-dependent protein phosphatase. To identify the molecular targets of calcineurin in C. elegans , yeast two-hybrid screening was performed. One of the candidates from the screening, CNP-1 is a novel protein that has two arrestin motifs. We have cloned and sequenced the full-length cDNA from cDNA library and this interaction between CNA-1, Calcineurin A in C. elegans , and CNP-1 was confirmed by GST pull-down assay. GFP expression of promoter region of cnp-1 was seen mainly in nerve cells from embryo to adult stage, which overlapped with that of cna-1 . We have also isolated a deletion mutant of cnp-1 (jh105) in which cnp-1 was deleted from the second exon to 3'UTR. Based on this molecular evidence, we suggest that this mutant is a functionally null mutant. The cnp-1 (jh105) mutants are viable and do not show any obvious developmental defect. However, cnp-1 (jh105) shows delayed egg laying response to food when refed after starvation whereas cnb-1 (jh103) , a loss of function mutant of calcineurin, is hypersensitive to food and cnp-1 (jh105) can suppress this hypersensitivity. Our data suggest that CNP-1 is indeed involved in calcineurin mediated signaling pathway.

Changhoon Jee et al. (2001) International C. elegans Meeting "Characterization of the shn-1, shank homologue in C. elegans"

Yoonsung Na, Joohong Ahnn, Changhoon Jee

[International C. elegans Meeting, 2001]

Shank is a novel family of the PSD (post-synaptic density) protein complex. It was found in rat brain and contains multiple sites for protein interaction including a PDZ (PSD-95, Disk-Large, ZO-1) domain that mediates binding to GKAP, ankyrin repeats, a SH3 domain, a SAM domain that mediates multimerization, and a proline-rich domain that binds cortactin. It was reported that these multiple protein-interactions cause shank to function as a scaffold protein in the PSD, cross-linking receptor/PSD-95 complexes and coupling them to regulators of the actin cytoskeleton. A shn-1 (C33B4.3), C. elegans homologue of shank, was found in the C. elegans genome database and shows about 40% identity over 1,000 amino acids. A shn-1 shows relatively high sequence identities in the regions of ankyrin repeats and the PDZ domain. GFP expression of promoter regions of shn-1 was seen mainly in pharyngeal muscle, head sensory neurons, nerve cords and the tail region. Whole-mount immunostaining patterns with shank-1 polyclonal antibodies showed similar expression patterns. shank-1 polyclonal antibodies were raised against ankyrin repeats-containing region of rat shank-1. This expression not only confirms our previous GFP expression results, but also shows the conservation of shank protein. We cloned and sequenced the full cDNA from a cDNA library and a EST clone from Yuji Kohara. Currently we are conducting RNAi experiments to observe loss-of function phenotypes and elucidate its biological role in C.elegans . Screening for deletion mutant by UV-TMP mutagenesis is also under way.

Changhoon Jee et al. (2003) International Worm Meeting "Identification and characterization of calcineurin binding protein in C. elegans"

Changhoon Jee, Joohong Ahnn

[International Worm Meeting, 2003]

Calcineurin is a Ca2+/calmodulin dependent Ser/Thr protein phosphatase. To identify the molecular targets of calcineurin action in C. elegans, yeast two-hybrid screening was performed. One of the candidates from the screening, cnp-1 (T12D8.4), shows 25% identity over 344 residues with human TBP-2/VDUP1, which has been recently reported as a negative regulator of Thioredoxin (TRX) function. Human TRX-binding protein 2(TBP-2), also known as Vitamin D3 up-regulated protein 1(VDUP1), was originally reported as an up-regulated gene in HL-60 cells treated with 1a, 25-dihydroxyvitamin D3, and significantly downregulated in chemically induced rat mammary tumors. We have cloned and sequenced the full cDNA from cDNA library and found that the gene structure predicted by database was incorrect. Complete DNA sequencing data showed that cnp-1 gene consists of 9 exons encoding a protein of 426 amino acid residues. Our sequencing results added one more exon, exactly 96 base pairs (32 amino acids) to the previously predicted one. To confirm in vitro interaction between calcineurin A and entire coding region of cnp-1, GST pull-down assay was conducted. GST fused full-length CNP-1 pulled down calcineurin A from the worm lysate. GFP expression of promoter region of cnp-1 was seen mainly in nerve cells from embryo to adult stage, which is similar to that of cna-1. We have isolated a deletion mutant of cnp-1 (jh105) by UV-TMP mutagenesis methods in which this gene was deleted from the beginning of exon2 to the end. Based on this molecular evidence, we suggest that this mutant is a functionally null mutant. We are in the process of characterizing phenotypes of this mutant.

Changhoon Jee et al. (2007) International Worm Meeting "Regulation of alternative states of locomotory behavior in C. elegans."

Changhoon Jee, Steven L. McIntire

[International Worm Meeting, 2007]

Sensory perception allows an animal to respond properly to its environment and to adapt to changing conditions. C. elegansexhibits alternative states of locomotory behavior on food, termed roaming and dwelling. These behavioral states are clearly modulated by environmental stimuli. Mutants with defects in sensory perception, such as che-2 (which has defective cilia), exhibit decreased roaming behavior and increased dwelling. Sensory perception also affects the growth and life span of C. elegans; che-2 mutants grow to a smaller body size and exhibit increased longevity. Overlapping neural or neuroendocrine pathways appear to regulate growth and the expression of different behavioral states. To identify genes acting downstream of sensory perception to regulate the expression of roaming verses dwelling, we developed an assay to identify suppressors of the locomotory defect of che-2. We screened 25,000 haploid genomes and identified 12 suppressors, which define at least 4 complementation groups. None of the suppressors alters the ciliary defect of che-2 (as assessed by dye filling) suggesting that the suppressors function downstream of sensory inputs. We have divided the suppressors into classes based on the suppression of other che-2 phenotypes. Only 1 of three classes suppresses the small body size of che-2. Molecular characterization of the identified suppressors may lead to an understanding of how complex behavioral pattern are generated in C. elegans.

Changhoon Jee et al. (2005) International Worm Meeting "Identification and characterization of cnp-1, calcineurin binding protein in C. elegans."

Changhoon Jee, Joohong Ahnn, Noelle D L'Etoile

[International Worm Meeting, 2005]

Calcineurin is a Ca2+/calmodulin-dependent protein phosphatase. To identify the molecular targets of calcineurin in C. elegans, yeast two-hybrid screening was performed. One of the candidates from the screening, CNP-1 is a novel protein that has two arrestin motifs. We have cloned and sequenced the full-length cDNA from cDNA library and this interaction between TAX-6, Calcineurin A in C. elegans, and CNP-1 was confirmed by GST pull-down assay. Binding region of CNP1 is a catalytic domain-containing region of TAX-6 and Phosphorylated CNP-1 is dephosphorylaed by purified C. elegans calcineurin in in vitro phosphatase assay. Our data suggest that CNP-1 is a substrate of calcineurin. cnp-1 is mainly expressed in nerve cells including ASH, ADL, ASK, ASJ, CEP and HSN neurons from embryo to adult stage. Deletion mutant of cnp-1 (jh105) shows delayed egg laying response to food when re-fed after starvation whereas cnb-1 (jh103), a loss of function mutant of calcineurin, is hypersensitive to food and cnp-1 (jh105) can suppress this hypersensitivity. Our data suggest that CNP-1 is indeed involved in calcineurin mediated signaling pathway. In addition, this suppression by cnp-1 (jh105) was restored by expressing CNP1 in adult stage using heat shock construct, suggesting that the CNP-1 is required for neuronal function rather than for neuronal development. Interestingly, cnp-1 (jh105) can also exhibits a defect in adaptation to hyperosmotic solution. To futher investigate the role of CNP-1 in adaptation, we are testing drop assay using various repellants.