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[
Methods Enzymol,
2008]
Apoptosome refers to the multimeric protein complex that mediates activation of an initiator caspase at the onset of apoptosis. This chapter describes the assembly of three related apoptosomes from mammals, fruit flies, and worms. The assembly of the mammalian apoptosome, which is responsible for the activation of caspase-9, involves Apaf-1 and requires cytochrome c and ATP/dATP binding. Assembly of the apoptosome in Drosophila melanogaster, which activates caspase-9 homologue Dronc, involves the Apaf-1 homologue known as Dark/Hac-1/Dapaf-1. In Caenorhabditis elegans, assembly of the CED-4 apoptosome requires EGL-1-mediated dissociation of CED-9 (a Bcl-2 homologue) from the CED-4-CED-9 complex and subsequent oligomerization of CED-4. Recent biochemical and structural investigation revealed insights into the assembly and function of the various apoptosomes.
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[
MicroPubl Biol,
2021]
Parkinson's disease (PD) patients have been shown to benefit greatly from intense physical activity (Schenkman et al. 2018). Recent studies have demonstrated that exercise causes changes in the levels of alpha-synuclein aggregate species, a hallmark of PD, in different mammalian animal models (Koo and Cho 2017; Shin et al. 2017; Zhou et al. 2017; Minakaki et al. 2019). However, questions still remain about how exercise affects specifically native alpha-synuclein protein species directly after the cessation of exercise and the longer-term downstream effects which exercise may have on organismal health. It was recently discovered that periods of thrashing in liquid solution, otherwise called swimming exercise, in C. elegans worms, induces many mechanisms invoked during mammalian exercise (Laranjeiro et al. 2017). This has provided an avenue for studying exercise conditions in various C. elegans models of neurodegeneration (Laranjeiro et al. 2019). In order to study the effect of exercise on native human alpha-synuclein protein species, we utilized the NL5901- pkIs2386 worm model of Parkinson's which contains human alpha-synuclein tagged to a yellow fluorescent protein (YFP) in the muscle cells (van Ham et al. 2008). We performed tissue analysis via Blue Native (BN) page westerns and confocal microscopy. In addition, because pharyngeal pumping is decreased while worms are swimming, we controlled for this effect by exposing worms in parallel to a period of food restriction (FR) conditions (Vidal-Gadea et al. 2012). We also performed thrashing assays to assess longer term downstream behavioral effects on the animals after either exercise or food restriction conditions.
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[
Genome Biol,
2007]
SUMMARY: The integrins are a superfamily of cell adhesion receptors that bind to extracellular matrix ligands, cell-surface ligands, and soluble ligands. They are transmembrane alphabeta heterodimers and at least 18 alpha and eight beta subunits are known in humans, generating 24 heterodimers. Members of this family have been found in mammals, chicken and zebrafish, as well as lower eukaryotes, including sponges, the nematode Caenorhabditis elegans (two alpha and one beta subunits, generating two integrins) and the fruitfly Drosophila melanogaster (five alpha and one beta, generating five integrins). The alpha and beta subunits have distinct domain structures, with extracellular domains from each subunit contributing to the ligand-binding site of the heterodimer. The sequence arginine-glycine-aspartic acid (RGD) was identified as a general integrin-binding motif, but individual integrins are also specific for particular protein ligands. Immunologically important integrin ligands are the intercellular adhesion molecules (ICAMs), immunoglobulin superfamily members present on inflamed endothelium and antigen-presenting cells. On ligand binding, integrins transduce signals into the cell interior; they can also receive intracellular signals that regulate their ligand-binding affinity. Here we provide a brief overview that concentrates mostly on the organization, structure and function of mammalian integrins, which have been more extensively studied than integrins in other organisms.
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MicroPubl Biol,
2021]
RMD-1 was discovered as a cytoplasmic regulator of microtubule dynamics in C. elegans and several highly homologous proteins were inferred from the C. elegans and human genome sequences (Oishi et al., 2007). One of the human homologs, RMD-3/PTPIP51, has an N-terminal extension relative to other RMDs that targets it to the mitochondrial outer membrane and which binds the endoplasmic reticulum (ER) protein VAPB (De Vos et al., 2012). This interaction mediates tethering of mitochondria to the ER in human cells (Stoica et al., 2014). None of the C. elegans RMDs have sequence homology with the N-terminal extension found on human RMD-3/PTPIP51, however, C. elegans RMD-2 has an N-terminal extension relative to the other RMDs and this extension has potential to form a transmembrane helix as determined by TMpred release 25 (https://embnet.vital-it.ch/software/TMPRED_form.html). RMD-2 is present in sperm whereas RMD-3 and RMD-6 are highly enriched in sperm (Ma et al., 2014). Paternal mitochondria are eventually degraded in the embryo (Sato and Sato, 2011). However, they are maintained, along with other sperm contents, at the opposite end of the zygote from the female meiotic spindle during meiosis (Fig. 1). We hypothesized that RMD-2, 3 and 6 on paternal mitochondria bind to the VAPB homolog, VPR-1, on maternal ER at fertilization to tether the sperm contents at the future posterior end of the zygote.
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[
Ann N Y Acad Sci,
2002]
The free radical theory of aging proposes that oxidative stress is one of the determinants of an organism?s life span. In Caenorhabditis elegans, genetic or environmental changes have been shown to modulate life span. Here we discuss whether changes in the generation and destruction of free radicals are implicated in these life span modulations. Changes in culture oxygen concentrations that are considered to reflect free radical generation perturb the life span. The life spans under high and low oxygen concentrations were shorter and longer, respectively, than those under normoxic conditions. Short-term exposure to high oxygen concentration lengthens the life span. This is considered to be the result of an increase in antioxidant defense induced by short-term oxidative stress. Mutations in genes such as
age-1 and
daf-2 that compose the insulin-like signaling network conferred oxidative stress resistance and an increase in Mn-SOD gene expression as well as life span extension.
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[
Ann N Y Acad Sci,
1993]
Excitation-contraction coupling is one of the interesting mechanisms to be elucidated from the point of view of calcium signal transduction in muscle contraction. Calcium channel genes were cloned and sequenced as the receptors of dihydropyridine and ryanodine receptor in mammals. Takeshima et al. confirmed that the ryanodine receptor has a molecular mass of 500,000 daltons with a large portion at the N-terminal, which was observed as a foot structure by electron microscopy, and the transmembrane domain at the C-terminal. The molecular architecture of the receptor was close to that of rabbit, mink, and human. The functional loss of the molecule causes malignant hyperthermia of swine. The ryanodine binding site and the channel-forming transmembrane structure were clarified by several other observations.
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[
Neuron,
2006]
Recent studies have begun to shed light on the molecular guidance cues controlling anterior-posterior axon guidance. Two recent studies in the current issue of Developmental Cell show that Wnts play critical roles in patterning processes and directing neuronal migration in C. elegans. Together with previous findings in vertebrates and flies, these new results establish conserved function of Wnts in A-P guidance.
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[
F1000Res,
2018]
Establishing and maintaining cell polarity are dynamic processes that necessitate complicated but highly regulated protein interactions. Phosphorylation is a powerful mechanism for cells to control the function and subcellular localization of a target protein, and multiple kinases have played critical roles in cell polarity. Among them, atypical protein kinase C (aPKC) is likely the most studied kinase in cell polarity and has the largest number of downstream substrates characterized so far. More than half of the polarity proteins that are essential for regulating cell polarity have been identified as aPKC substrates. This review covers mainly studies of aPKC in regulating anterior-posterior polarity in the worm one-cell embryo and apical-basal polarity in epithelial cells and asymmetrically dividing cells (for example, <i>Drosophila</i> neuroblasts). We will go through aPKC target proteins in cell polarity and discuss various mechanisms by which aPKC phosphorylation controls their subcellular localizations and biological functions. We will also review the recent progress in determining the detailed molecular mechanisms in spatial and temporal control of aPKC subcellular localization and kinase activity during cell polarization.
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[
Redox Rep,
2004]
Several investigators have generated long-lived nematode worms (Caenorhabditis elegans) in the past decade by mutation of genes in the organism in order to study the genetics of aging and longevity. Dozens of longevity assurance genes (LAG) that dramatically increase the longevity of this organism have been identified. All long-lived mutants of C. elegans are also resistant to environmental stress, such as high temperature, reactive oxygen species (ROS), and ultraviolet irradiation. Double mutations of some LAGs further extended life span up to 400%, providing more insight into cellular mechanisms that put limits on the life span of organisms. With the availability of the LAG mutants and the combined DNA microarray and RNAi technology, the understanding of actual biochemical processes that determine life span is within reach: the downstream signal transduction pathway may regulate life span by up-regulating pro-longevity genes such as those that encode antioxidant enzymes and/or stress-response proteins, and down-regulating specific life-shortening genes. Furthermore, longevity could be modified through chemical manipulation. Results from these studies further support the free radical theory of aging, suggest that the molecular mechanism of aging process may be shared in all organisms, and provide insight for therapeutic intervention in age-related diseases.