Finch CE et al. (2001) Annu Rev Genomics Hum Genet "The genetics of aging."

Ruvkun G, Finch CE

[Annu Rev Genomics Hum Genet, 2001]

The genetic analysis of life span has only begun in mammals, invertebrates, such as Caenorhabditis elegans and Drosophila, and yeast. Even at this primitive stage of the genetic analysis of aging, the physiological observations that rate of metabolism is intimately tied to life span is supported. In many examples from mice to worms to flies to yeast, genetic variants that affect life span also modify metabolism. Insulin signaling regulates life span coordinately with reproduction, metabolism, and free radical protective gene regulation in C. elegans. This may be related to the findings that caloric restriction also regulates mammalian aging, perhaps via the modulation of insulin-like signaling pathways. The nervous system has been implicated as a key tissue where insulin-like signaling and free radical protective pathways regulate life span in C. elegans and Drosophila. Genes that determine the life span could act in neuroendocrine cells in diverse animals. The involvement of insulin-like hormones suggests that the plasticity in life spans evident in animal phylogeny may be due to variation in the timing of release of hormones that control vitality and mortality as well as variation in the response to those hormones. Pedigree analysis of human aging may reveal variations in the orthologs of the insulin pathway genes and coupled pathways that regulate invertebrate aging. Thus, genetic approaches may identify a set of circuits that was established in ancestral metazoans to regulate their longevity.

Inoue T et al. (1997) Arch Biochem Biophys "Caenorhabditis elegans has two isozymic forms, CE-1 and CE-2, of fructose-1,6-bisphosphate aldolase which are encoded by different genes."

Takasaki Y, Inoue T, Nikoh N, Miyata T, Hori K, Kusakabe T, Yatsuki H, Joh K

[Arch Biochem Biophys, 1997]

Two distinct types of cDNAs for fructose-1,6-bisphosphate (FBP) aldolase, Ce-1 and Ce-2, have been isolated from nematode Caenorhabditis elegans, and the respective recombinant aldolase isozymes, CE-1 and CE-2, have been purified and characterized. The Ce-1 and Ce-2 are 1282 and 1248 bp in total length, respectively, and both have an open reading frame of 1098 bp, which encodes 366 amino acid residues. The entire amino acid sequences deduced from Ce-1 and Ce-2 show a high degree of identity to one another and to those of vertebrate and invertebrate aldolases. The highest sequence diversity was found in the carboxyl-terminal region that corresponds to one of the isozyme group-specific sequences of vertebrate aldolase isozymes that play a role in determining isozyme-specific functions. Southern blot analysis suggests that CE-1 and CE-2 are encoded by different genes. Concerning general or kinetic properties, CE-2 is quite different from CE-1. CE-1 exhibits unique characteristics which are not identical to any aldolase isozymes previously reported, whereas CE-2 is similar to vertebrate aldolase C. These results suggest that CE-2 might preserve the properties of a progenitor aldolase with a moderate preference for FBP over fructose 1-phosphate (F1P) as a substrate, whereas CE-1 evolved to act as an intrinsic enzyme that exhibits a much broader substrate specificity than dose CE-2.

Margalit A et al. (2005) Novartis Found Symp "A lamin-dependent pathway that regulates nuclear organization, cell cycle progression and germ cell development."

Wilson KL, Gruenbaum Y, Fridkin A, Liu J, Margalit A

[Novartis Found Symp, 2005]

The C. elegans genome encodes a single lamin protein (Ce-lamin), three LEM domain proteins (Ce-emerin, Ce-MAN1 and LEM-3) and a single BAF protein (Ce-BAF). Down-regulation of Ce-lamin causes embryonic lethality. Abnormalities include rapid changes in nuclear morphology during interphase, inability of cells to complete mitosis, abnormal condensation of chromatin, clustering of nuclear pore complexes (NPCs), and missing or abnormal germ cells. Ce-emerin and Ce-MAN1 are both embedded in the inner nuclear membrane, and both bind Ce-lamin and Ce-BAF; in addition, both require Ce-lamin for their localization. Mutations in human emerin cause X-linked recessive Emery-Dreifuss muscular dystrophy. In C. elegans, loss of Ce-emerin alone has no detectable phenotype, while loss of 90% Ce-MAN1 causes approximately 15% embryonic lethality. However in worms that lack Ce-emerin, a approximately 90% reduction of Ce-MAN1 is lethal to all embryos by the 100-cell stage, with a phenotype involving chromatin condensation and repeated cycles of anaphase chromosome bridging and cytokinesis. The anaphase-bridged chromatin retained a mitosis-specific phosphohistone H3 epitope, and failed to recruit detectable Ce-lamin or Ce-BAF. Down-regulation of Ce-BAF showed similar phenotypes. These findings suggest that lamin, LEM-domain proteins and BAF are part of a lamina network essential for chromatin organization and cell division, and that Ce-emerin and Ce-MAN1 share at least one and possibly multiple overlapping functions, which may be relevant to Emery-Dreifuss muscular dystrophy.

Angelo RG et al. (2000) J Biol Chem "Characterization of structural features that mediate the tethering of Caenorhabditis elegans protein kinase A to a novel A kinase anchor protein. Insights into the anchoring of PKAI isoforms."

Angelo RG, Rubin CS

[J Biol Chem, 2000]

Caenorhabditis elegans protein kinase A (PKAI(CE)) is tethered to organelles in vivo. A unique A kinase anchor protein (AKAP(CE)) avidly binds the RI-like regulatory subunits (R(CE)) of PKAI(CE) and stringently discriminates against RIIalpha and RIIbeta subunits, the preferred ligands for classical AKAPs. We elucidated structural features that stabilize AKAP(CE).R(CE) complexes and confer atypical R isoform specificity on the anchor protein. Three large aliphatic amino acids (Leu(236), Ile(248), and Leu(252)) in the tethering domain of AKAP(CE) (residues 236-255) are crucial for ligation of R(CE). Their side chains apparently generate a precisely configured hydrophobic binding pocket that accommodates an apolar surface on R(CE) dimers. Basic residues (His(254)-Arg(255)-Lys(256)) at the C terminus of the tethering site set an upper limit on affinity for R(CE.) A central dipeptide (Phe(243)-Ser(244)) contributes critical and distinctive properties of the tethering site. Ser(244) is essential for selective binding of R(CE) and exclusion of RII isoforms. The aromatic hydrophobic character of Phe(243) ensures maximal R(CE) binding activity, thereby supporting a "gatekeeper" function of Ser(244). Substitution of Phe(243)-Ser(244) with Leu-Val generated an RII-specific AKAP. R(CE) and RII subunits contain similar dimerization domains. AKAP-binding domains of R(CE) (residues 23-47) and RII differ markedly in size, amino acid sequence, and docking specificity. Four hydrophobic residues (Cys(23), Val(27), Ile(32), and Cys(44)) in R(CE) are crucial for avid binding with AKAP(CE), whereas side chains from Leu(20), Leu(35), Val(36), Ile(40), and Ile(41) have little impact on complex formation. Tyr(26) is embedded in the docking domain, but its aromatic ring is required for R(CE)-R(CE) dimerization. Residues 236-255 in AKAP(CE) also constitute a binding site for mammalian RIalpha. RIalpha (PKAIalpha) is tightly sequestered by AKAP(CE) in vitro (K(D) = approximately 10 nM) and in the environment of intact cells. The tethering domain of AKAP(CE) provides a molecular module for manipulating intracellular localization of RI and elucidating functions of anchored PKAI in eukaryotes.

Liu J et al. (2003) Proc Natl Acad Sci U S A "MAN1 and emerin have overlapping function(s) essential for chromosome segregation and cell division in Caenorhabditis elegans."

Gruenbaum Y, Neufeld E, Lee KK, Wilson KL, Liu J, Segura-Totten M

[Proc Natl Acad Sci U S A, 2003]

Emerin and MAN1 are LEM domain-containing integral membrane proteins of the vertebrate nuclear envelope. The function of MAN1 is unknown, whereas emerin is known to interact with nuclear lamins, barrier-to-auto integration factor (BAF), nesprin-1alpha, and a transcription repressor. Mutations in emerin cause X-linked recessive Emery-Dreifuss muscular dystrophy. Emerin and MAN1 homologs are both conserved in Caenorhabditis elegans, but loss of Ce-emerin has no detectable phenotype. We therefore used C elegans to test the hypothesis that Ce-MAN1 overlaps functionally with Ce-emerin. Supporting this model, Ce-MAN1 interacted directly with Ce-lamin and Ce-BAF in vitro and required Ce-lamin for its nuclear envelope localization. Interestingly, RNA interference-mediated removal of approximate to90% of Ce-MAN1 was lethal to approximate to15% of embryos. However, in the absence of Ce-emerin, approximate to90% reduction of Ce-MAN1 was lethal to all embryos by the 100-cell stage, with a phenotype involving repeated cycles of anaphase chromosome bridging and cytokinesis ["cell untimely torn" (cut) phenotype]. Immunostaining showed that the anaphase-bridged chromatin specifically retained a mitosis-specific phosphohistone H3 epitope and failed to recruit detectable Ce-lamin or Ce-BAF. These findings show that LEM domain proteins are essential for cell division and that Ce-emerin and Ce-MAN1 share at least one and possibly multiple overlapping functions, which may be relevant to Emery-Dreifuss muscular

Kariya K-i et al. (1997) International C. elegans Meeting "C. ELEGANS HOMOLOGS OF RALGDS, AF-6, CDC25 AND PHOSPHOLIPASE Cb INTERACT WITH LET-60"

Watari Y, Liao Y, Hu CD, Shibatohge M, Kataoka T, Kariya K-i, Goshima M

[International C. elegans Meeting, 1997]

Mammalian Ras proteins regulate multiple effectors including Raf family, RalGDS family and AF-6. To understand all signaling pathways regulated by Let-60 in C. elegans , we screened for Let-60-binding proteins by the yeast two-hybrid system (thanks to Dr. R. Barstead for the lACT-RB2 library). The screen identified partial cDNA clones encoding not only C. elegans Raf but also C. elegans homologs of RalGDS (Ce-RalGDS), of AF-6 (Ce-AF-6), of Cdc25 (Ce-Cdc25) and of phospholipase Cb (Ce-PLCb). Flanking cDNA sequences were obtained by the spliced leader sequence PCR or from Dr. Y. Kohara's EST clones. Ce-RalGDS contained the middle Cdc25 homology domain and the C-terminal Ras-interacting domain (RID) homologous to those of RalGDS. Ce-AF-6 contained the N-terminal RID and the middle GLGF/DHR motif homologous to those of AF-6. Ce-Cdc25 contained a proline-rich region, possible PH domain, and a Cdc25 homology domain similar to that of Cdc25Mm/RasGRF. Ce-PLCb contained PH, X, Y and C2 domains found in mammalian counterpart. However, the N-terminal Cdc25 homology domain (similar to those of Sos proteins) and the C-terminal RID (300 amino acids) of Ce-PLCb were unique. These proteins bound to mammalian Ha-Ras in the two-hybrid system, but the bindings were abolished by various mutations within the effector domain of Ha-Ras. MBP-fusion proteins of Ce-RalGDS RID and Ce-PLCb RID bound Ha-Ras in vitro in a GTP-dependent manner. To examine functions of the newly identified Let-60 effector candidates, worms carrying Tc1-insertions within the genes were isolated (for Ce-RalGDS, Ce-PLCb and Ce-AF-6), and deletion derivatives (only heterozygotes) were obtained (for Ce-RalGDS and Ce-PLCb). Phenotypic analyses will be presented if homozygotes are viable.

Margalit A et al. (2005) Proc Natl Acad Sci U S A "Barrier-to-autointegration factor is required to segregate and enclose chromosomes within the nuclear envelope and assemble the nuclear lamina."

Segura-Totten M, Gruenbaum Y, Margalit A, Wilson KL

[Proc Natl Acad Sci U S A, 2005]

Barrier-to-autointegration factor (BAF) binds dsDNA, LEM-domain proteins, and lamins. Caenorhabditis elegans BAF requires Ce-lamin and two LEM-domain proteins (Ce-emerin and Ce-MAN1) to localize during nuclear assembly. It was unknown whether Ce-lamin and LEM proteins, in turn, depend on Ce-BAF (mutually dependent structural roles). RNA interference-mediated down-regulation of Ce-BAF caused gross defects in chromosome segregation, chromatin decondensation, and mitotic progression as early as the two-cell stage, and embryos died at the approximately 100-cell stage. Nuclear pores reassembled, whereas Ce-lamin, Ce-emerin, and Ce-MAN1 bound chromatin but remained patchy and disorganized. The nuclear membranes formed but failed to enclose anaphase-bridged chromatin. Time-lapse imaging showed two phenotypes: anaphase-bridged chromatin that eventually resolved, and segregated chromatin that returned to the midzone. Thus, the assembly of BAF, lamins, and LEM-domain proteins is mutually dependent, and is required to capture segregated chromosomes within the nascent nuclear envelope. Embryos that escaped lethality by down-regulation of Ce-BAF grew into sterile adults with misplaced distal tip cells and gonads, further suggesting that mild postembryonic reductions in BAF disrupt tissue-specific functions.

Rossbach LM et al. (2022) Environ Sci Technol "Synchrotron XRF Analysis Identifies Cerium Accumulation Colocalized with Pharyngeal Deformities in CeO2 NP-Exposed Caenorhabditis elegans."

Brede DA, Olsson RMS, Janssens K, Lind OC, Rossbach LM, Oughton DH, Falkenberg G, Cagno S, Nuyts G

[Environ Sci Technol, 2022]

A combination of synchrotron radiation-based elemental imaging, in vivo redox status analysis, histology, and toxic responses was used to investigate the uptake, biodistribution, and adverse effects of Ce nanoparticles (CeO2 NP; 10 nm; 0.5-34.96 mg Ce L-1) or Ce(NO3)3 (2.3-26 mg Ce L-1) in Caenorhabditis elegans. Elemental mapping of the exposed nematodes revealed Ce uptake in the alimentary canal prior to depuration. Retention of CeO2 NPs was low compared to that of Ce(NO3)3 in depurated individuals. X-ray fluorescence (XRF) mapping showed that Ce translocation was confined to the pharyngeal valve and foregut. Ce(NO3)3 exposure significantly decreased growth, fertility, and reproduction, caused slightly reduced fecundity. XRF mapping and histological analysis revealed severe tissue deformities colocalized with retained Ce surrounding the pharyngeal valve. Both forms of Ce activated the sod-1 antioxidant defense, particularly in the pharynx, whereas no significant effects on the cellular redox balance were identified. The CeO2 NP-induced deformities did not appear to impair the pharyngeal function or feeding ability as growth effects were restricted to Ce(NO3)3 exposure. The results demonstrate the utility of integrated submicron-resolution SR-based XRF elemental mapping of tissue-specific distribution and adverse effect analysis to obtain robust toxicological evaluations of metal-containing contaminants.

Kamikura DM et al. (2003) Genes Dev "Lipoprotein receptors and a disabled family cytoplasmic adaptor protein regulate EGL-17/FGF export in C. elegans."

Cooper JA, Kamikura DM

[Genes Dev, 2003]

Growth factors and morphogens need to be secreted to act on distant cells during development and in response to injury. Here, we report evidence that efficient export of a fibroblast growth factor (FGF), EGL-17, from the Caenorhabditis elegans developing vulva requires the lipoprotein receptor-related proteins Ce-LRP-1 and Ce-LRP-2 and a cytoplasmic adaptor protein, Ce-DAB-1 (Disabled). Lipoprotein receptors are transmembrane proteins best known for their roles in endocytosis. Ce-LRP-1 and Ce-LRP-2 possess a conserved intraluminal domain that can bind to EGL-17, as well as a cytosolic FXNPXY motif that can bind to Ce-DAB-1. Ce-DAB-1 contains signals that confer subcellular localization to Golgi-proximal vesicles. These results suggest a model in which Ce-DAB-1 coordinates selection of receptors and cargo, including EGL-17, for transport through the secretory pathway.

Agulnik SI et al. (1997) Genome "Three novel T-box genes in Caenorhabditis elegans."

Ruvinsky I, Agulnik SI, Silver LM

[Genome, 1997]

The T-box gene family consists of members that share a unique DNA binding domain. The best characterized T-box gene, Brachyury or T, encodes a transcription factor that plays an important role in early vertebrate development. Seven other recently described mouse T-box genes are also expressed during development. In the nematode Caenorhabditis elegans, four T-box genes have been characterized to date. In this study, we describe three new C. elegans T-box genes, named Ce-tbx-11, Ce-tbx-12, and Ce-tbx-17. Ce-tbx-11 and Ce-tbx-17 were uncovered through the sequencing efforts of the C. elegans Genome Project. Ce-tbx-12 was uncovered through degenerate PCR analysis of C. elegans genomic DNA. Ce-tbx-11 and Ce-tbx-17 are located in close proximity to the four other previously described T-box genes in the central region of chromosome III. In contrast, Ce-tbx-12 maps alone to chromosome II. Phylogenetic analysis of all known T-box domain sequences provides evidence of an ancient origin for this gene family.