Musset-Bilal F et al. (1994) Worm Breeder's Gazette "Characterization of the C. elegans Basement Membrane-Associated Protein SPARC"

Musset-Bilal F, Schwarzbauer JE, Ryan CS

[Worm Breeder's Gazette, 1994]

Characterization of the C. elegans Basement Membrane- Associated Frederique Musset-Bilal, Carol S. Ryan, and Jean E. Schwarzbauer Department of Molecular Biology, Princeton University, Princeton NJ 08544

Babu V et al. (2014) DNA Repair (Amst) "A C. elegans homolog of the Cockayne syndrome complementation group A gene."

Babu V, Hofmann K, Schumacher B

[DNA Repair (Amst), 2014]

Cockayne syndrome (CS) is a debilitating and complex disorder that results from inherited mutations in the CS complementation genes A and B, CSA and CSB. The links between the molecular functions of the CS genes and the complex pathophysiology of CS are as of yet poorly understood and are the subject of intense debate. While mouse models reflect the complexity of CS, studies on simpler genetic models might shed new light on the consequences of CS mutations. Here we describe a functional homolog of the human CSA gene in Caenorhabditis elegans. Similar to its human counterpart, mutations in the nematode csa-1 gene lead to developmental growth defects as a consequence of DNA lesions.

Okur MN et al. (2020) Aging Cell "Cockayne syndrome proteins CSA and CSB maintain mitochondrial homeostasis through NAD+ signaling."

Tiwari V, Okur MN, Bohr VA, Croteau DL, Fang EF, Fivenson EM

[Aging Cell, 2020]

Cockayne syndrome (CS) is a rare premature aging disease, most commonly caused by mutations of the genes encoding the CSA or CSB proteins. CS patients display cachectic dwarfism and severe neurological manifestations and have an average life expectancy of 12years. The CS proteins are involved in transcription and DNA repair, with the latter including transcription-coupled nucleotide excision repair (TC-NER). However, there is also evidence for mitochondrial dysfunction in CS, which likely contributes to the severe premature aging phenotype of this disease. While damaged mitochondria and impaired mitophagy were characterized in mice with CSB deficiency, such changes in the CS nematode model and CS patients are not fully known. Our cross-species transcriptomic analysis in CS postmortem brain tissue, CS mouse, and nematode models shows that mitochondrial dysfunction is indeed a common feature in CS. Restoration of mitochondrial dysfunction through NAD⁺ supplementation significantly improved lifespan and healthspan in the CS nematodes, highlighting mitochondrial dysfunction as a major driver of the aging features of CS. In cerebellar samples from CS patients, we found molecular signatures of dysfunctional mitochondrial dynamics and impaired mitophagy/autophagy. In primary cells depleted for CSA or CSB, this dysfunction can be corrected with supplementation of NAD⁺ precursors. Our study provides support for the interconnection between major causative aging theories, DNA damage accumulation, mitochondrial dysfunction, and compromised mitophagy/autophagy. Together, these three agents contribute to an accelerated aging program that can be averted by cellular NAD⁺ restoration.

Morrison GE et al. (1995) International C. elegans Meeting "lrn-1 and lrn-2 Block Associative Learning in C. elegans."

Morrison GE, Wen JYM, Runciman S, Neghandi H, van der Kooy D, Kumar N

[International C. elegans Meeting, 1995]

The nematode C. elegans can be conditioned using a classical conditioning paradigm based on its chemotactic responses to the conditioning stimuli (CS), Na+ (NaCH3CHOO) and Cl- (NH4Cl), which are equally preferred under baseline conditions. After exposure to one of the CS ions (CS+) in the presence of the US (E. coli, a food source), counterbalanced by an equal exposure to the alternate ion (CS-) in the absence of the US, the animals demonstrate a significant preference for the CS+ ion on testing. Using an EMS screen, we isolated two lines of mutant animals (lrn-1 and lrn-2) that after conditioning displayed the equivalent preferences for the CS+ and CS- ions shown by unconditioned wild type worms. Using garlic (an aversive stimulus) as a US, wild type worms show a conditioned avoidance for the ion (CS+) that was paired with the garlic, whereas the two mutant lines displayed equivalent preferences for the CS+ and CS- ions after conditioning. We used a short-term assay to determine the effects of the two mutations on short- and long-term memory. After conditioning for minutes, the initial test headings (after 30 sec) of individual wild type animals towards the CS+ and CS- ions are not significantly different from the learning scores in our original, 90 min test paradigm (~75% approach to the CS+ ion). However, after conditioning, initial test headings of individual mutant animals remain balanced, 50% approaching the CS+ ion and 50% approaching the CS- ion. These two mutants are normal in motor and sensory capabilities since the approaches to point sources of both CS ions and the US (E. coli) are similar to those of wild type animals in both the accumulation rates and overall preferences. As well, the two mutants are capable of normal non-associative learning (habituation) to the ions used as conditioning stimuli in the associative learning paradigm. Using the sequence tagged site strategy for C. elegans and multiplex PCR techniques, we have begun mapping the two mutations through the generation of Bergerac/mutant N2 hybrids.

Cockayne syndrome proteins CSA and CSB maintain mitochondrial homeostasis through NAD+ signaling [Agilent-020186 array]

Cockayne syndrome (CS) is a rare premature aging disease, which in the majority of cases is caused by mutations of the genes encoding the CSA or CSB proteins. CS patients display cachectic dwarfism and severe neurological manifestations and die by 12 years of age on average. The CS proteins are involved in transcription and DNA repair, including a specialized form of DNA repair called transcription-coupled nucleotide excision repair (TC-NER). However, there is also evidence for mitochondrial dysfunction in CS, likely contributing to the severe premature aging phenotype of this disease. Our cross-species transciptomic analysis in CS postmortem brain tissue, CS mouse and C. elegans models showed that mitochondrial dysfunction is indeed a common feature in CS. Interestingly, the restoration of mitochondrial dysfunction through NAD+ supplementation significantly improved lifespan and healthspan in the C. elegans models of CS, highlighting mitochondrial dysfunction as a major driver of the aging features of CS. We proceeded to perform molecular studies on cerebellar samples obtained from CS patients. We found that these patients exhibited molecular signatures of dysfunctional mitochondrial dynamics that can be corrected with NAD+ supplementation in primary cells with depleted CSA or CSB. Our study provides support for the interconnection between two major aging theories, DNA damage and mitochondrial dysfunction. Together these two agents contribute to an accelerated aging program that can be averted by NAD+ supplementation.

deg-1 : des-4

maternal effect suppressor of cs embryonic lethality caused by deg-1(u506);does not suppress larval degenerations

cholesterol starvation : daf-16

DAF-16 was translocated from the cytoplasm to the nucleus in the worms grown in cholesterol starvation (CS).

Kawasaki I et al. (2013) Mol Cells "Cholesterol-responsive metabolic proteins are required for larval development in Caenorhabditis elegans."

Shin YK, Shim YH, Yun YJ, Kawasaki I, Jeong MH

[Mol Cells, 2013]

Caenorhabditis elegans, a cholesterol auxotroph, showed defects in larval development upon cholesterol starvation (CS) in a previous study. To identify cholesterol-responsive proteins likely responsible for the larval arrest upon CS, a comparative proteomic analysis was performed between C. elegans grown in normal medium supplemented with cholesterol (CN) and those grown in medium not supplemented with cholesterol (cholesterol starvation, CS). Our analysis revealed significant change (more than 2.2-fold, p < 0.05) in nine proteins upon CS. Six proteins were down-regulated [CE01270 (EEF-1A.1), CE08852 (SAMS-1), CE11068 (PMT-2), CE09015 (ACDH-1), CE12564 (R07H5.8), and CE09655 (RLA-0)], and three proteins were up-regulated [CE29645 (LEC-1), CE16576 (LEC-5), and CE01431 (NEX-1)]. RNAi phenotypes of two of the down-regulated genes, R07H5.8 (adenosine kinase) and rla-0 (ribosomal protein), in CN were similar to that of larval arrest in CS, and RNAi of a down-regulated gene, R07H5.8, in CS further enhanced the effects of CS, suggesting that down-regulation of these genes is likely responsible for the larval arrest in CS. All three up-regulated genes contain putative DAF-16 binding sites and mRNA levels of these three genes were all decreased in daf-16 mutants in CN, suggesting that DAF-16 activates expression of these genes.

Kumar N et al. (1991) International C. elegans Meeting "CLASSICAL CONDITIONING IN C. ELEGANS;"

van der Kooy D, Wen JYM, Culotti JG, Kumar N

[International C. elegans Meeting, 1991]

The nematode is an excellent model system in which to pursue a neurogenetic analysis of behavior. In particular, we chose to train nematodes in a classical conditioning paradigm in order to focus on the cellular and molecular bases of learning and memory. Initially, 2 chemotactically attractive ions Na+ (NaCH3COO) and Cl- (NH4Cl) were chosen as conditioned stimuli (CSs) and E. coli, a rewarding food source, was used as the unconditioned stimuli (US). The animals were trained by exposing them to a constant concentration of one ion (CS+) paired with the US followed by exposure to the other ion (CS-) in the absence of the US. The experiment was counterbalanced for which CS was paired with the US and for the order of CS presentation. The testing consisted of placing approximately 100 of the trained animals between point gradients of each CS (in the absence of the US) and allowing them to migrate towards one of the gradient centers. CS levels were balanced such that naive animals displayed equal chemotactic preferences for either CS. Immediately after one CS+ and one CS- pairing, 67.1_3.1% of the animals demonstrated a preference for the CS paired with the US. A 5 hour food deprivation prior to training increased the preference for the CS+ ion to 77.3_2.6%. These animals showed evidence of memory for the association at 7 hours post-training but by 27 hours post-training their test performance was no longer significantly different (56.5+9.8 %) from controls. The nematodes learned inhibitory relationships (the CS- predicts the absence of food) as well as excitatory ones (the CS+ predicts the presence of food). We have also been able to demonstrate conditioned aversion learning by replacing E. coli, an appetitive US, with an aversive garlic extract. In this case nematodes can be trained to avoid the CS+ ion. In addition to being sensitive to changes in the US, the nematode can also learn about different CSs. If distinct temperatures are used as CSs instead of ions, food deprived nematodes learn to exhibit a preference for the temperature that was paired with the food reward. Thus, a desirable range of conditioned stimuli and conditioning responses can be utilized in learning paradigms with C. elegans. Presently we are undertaking a mutational screen for learning and memory mutants.

chst-1

Caenorhabditis elegans

Enables chondroitin 4-sulfotransferase activity. Involved in chondroitin sulfate biosynthetic process and positive regulation of response to oxidative stress. Predicted to be located in Golgi membrane.