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1.
spe-12 encodes a sperm cell surface protein that promotes spermiogenesis in Caenorhabditis elegans 总被引:1,自引:0,他引:1
During spermiogenesis, Caenorhabditis elegans spermatids activate and mature into crawling spermatozoa without synthesizing new proteins. Mutations in the spe-12 gene block spermatid activation, rendering normally self-fertile hermaphrodites sterile. Mutant males, however, are fertile. Surprisingly, when mutant hermaphrodites mate with a male, their self-spermatids activate and form functional spermatozoa, presumably due to contact with male seminal fluid. Here we show that, in addition to its essential role in normal activation of hermaphrodite-derived spermatids, SPE-12 also plays a supplementary but nonessential role in mating-induced activation. We have identified the spe-12 gene, which encodes a novel protein containing a single transmembrane domain. spe-12 mRNA is expressed in the sperm-producing germ line and the protein localizes to the spermatid cell surface. We propose that SPE-12 functions downstream of both hermaphrodite- and male-derived activation signals in a spermatid signaling pathway that initiates spermiogenesis. 相似文献
2.
Insulin-like growth factor II acts as an autocrine growth and motility factor in human rhabdomyosarcoma tumors 总被引:8,自引:0,他引:8
O M El-Badry C Minniti E C Kohn P J Houghton W H Daughaday L J Helman 《Cell growth & differentiation》1990,1(7):325-331
Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and appears to arise from developing striated muscle-forming cells. Since insulin-like growth factor II (IGF-II) is involved in normal muscle growth and maturation and elevated IGF-II mRNA levels have previously been reported in rhabdomyosarcomas, we have been studying the possible role of IGF-II in the unregulated growth and invasive potential of these embryonal tumors. In this study, we demonstrate that 13 of 14 rhabdomyosarcoma tumors express high levels of IGF-II mRNA relative to normal adult muscle and also express mRNA for the type I IGF receptors on their cell surface, the receptor thought to mediate the effects of IGF-II on muscle cells. We have established several rhabdomyosarcoma cell lines in mitogen-free media and demonstrate that these cells express type I IGF receptors on their cell surface and secrete IGF-II into the media. Exogenous IGF-II is able to stimulate cellular motility in these cell lines as assayed in a modified Boyden chamber. Finally, alpha IR-3, a type I receptor antagonist, inhibits the growth of these cell lines in serum-free media but does not inhibit IGF-II-induced motility of these cells. These data suggest that endogenously produced IGF-II functions as an autocrine growth and motility factor in many rhabdomyosarcoma tumors. The mitogenic actions of IGF-II are mediated through a domain of the type I IGF receptor that is blocked by alpha IR-3. IGF-II-induced motility may be mediated through an alternative signaling pathway. 相似文献
3.
Alexandria A. Oviatt Jissy A. Kuriappan Elirosa Minniti Kendra R. Vann Princess Onuorah Anna Minarini Marco De Vivo Neil Osheroff 《Bioorganic & medicinal chemistry letters》2018,28(17):2961-2968
Etoposide is an anticancer drug that acts by inducing topoisomerase II-mediated DNA cleavage. Despite its wide use, etoposide is associated with some very serious side-effects including the development of treatment-related acute myelogenous leukemias. Etoposide targets both human topoisomerase IIα and IIβ. However, the contributions of the two enzyme isoforms to the therapeutic vs. leukemogenic properties of the drug are unclear. In order to develop an etoposide-based drug with specificity for cancer cells that express an active polyamine transport system, the sugar moiety of the drug has been replaced with a polyamine tail. To analyze the effects of this substitution on the specificity of hybrid molecules toward the two enzyme isoforms, we analyzed the activity of a series of etoposide-polyamine hybrids toward human topoisomerase IIα and IIβ. All of the compounds displayed an ability to induce enzyme-mediated DNA cleavage that was comparable to or higher than that of etoposide. Relative to the parent drug, the hybrid compounds displayed substantially higher activity toward topoisomerase IIβ than IIα. Modeling studies suggest that the enhanced specificity may result from interactions with Gln778 in topoisomerase IIβ. The corresponding residue in the α isoform is a methionine. 相似文献
4.
Alicia N Minniti Daniela L Rebolledo Paula M Grez Ricardo Fadic Rebeca Aldunate Irene Volitakis Robert A Cherny Carlos Opazo Colin Masters Ashley I Bush Nibaldo C Inestrosa 《Molecular neurodegeneration》2009,4(1):1-17
Background
The amyloid β-peptide is a ubiquitous peptide, which is prone to aggregate forming soluble toxic oligomers and insoluble less-toxic aggregates. The intrinsic and external/environmental factors that determine Aβ aggregation in vivo are poorly understood, as well as the cellular meaning of this process itself. Genetic data as well as cell biological and biochemical evidence strongly support the hypothesis that Aβ is a major player in the onset and development of Alzheimer's disease. In addition, it is also known that Aβ is involved in Inclusion Body Myositis, a common myopathy of the elderly in which the peptide accumulates intracellularly.Results
In the present work, we found that intracellular Aβ aggregation in muscle cells of Caenorhabditis elegans overexpressing Aβ peptide is affected by two single amino acid substitutions, E22G (Arctic) and V18A (NIC). Both variations show decrease intracellular amyloidogenesis compared to wild type Aβ. We show that intracellular amyloid aggregation of wild type Aβ is accelerated by Cu2+ and diminished by copper chelators. Moreover, we demonstrate through toxicity and behavioral assays that Aβ-transgenic worms display a higher tolerance to Cu2+ toxic effects and that this resistance may be linked to the formation of amyloid aggregates.Conclusion
Our data show that intracellular Aβ amyloid aggregates may trap excess of free Cu2+ buffering its cytotoxic effects and that accelerated intracellular Aβ aggregation may be part of a cell protective mechanism. 相似文献5.
6.
Sergio H. Simonetta Andrés Romanowski Alicia N. Minniti Nibaldo C. Inestrosa Diego A. Golombek 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(9):821-828
Circadian rhythms control several behaviors through neural networks, hormones and gene expression. One of these outputs in invertebrates, vertebrates and plants is the stress resistance behavior. In this work, we studied the circadian variation in abiotic stress resistance of adult C. elegans as well as the genetic mechanisms that underlie such behavior. Measuring the stress resistance by tap response behavior we found a rhythm in response to osmotic (NaCl LC(50) = 340 mM) and oxidative (H(2)O(2) LC(50) = 50 mM) shocks, with a minimum at ZT0 (i.e., lights off) and ZT12 (lights on), respectively. In addition, the expression of glutathione peroxidase (C11E4.1) and glycerol-3-phosphate dehydrogenase (gpdh-1) (genes related to the control of stress responses) also showed a circadian fluctuation in basal levels with a peak at night. Moreover, in the mutant osr-1 (AM1 strain), a negative regulator of the gpdh-1 pathway, the osmotic resistance rhythms were masked at 350 mM but reappeared when the strain was treated with a higher NaCl concentration. This work demonstrates for the first time that in the adult nematode, C. elegans stress responses vary daily, and provides evidence of an underlying rhythmic gene expression that governs these behaviors. 相似文献
7.
This paper presents a computer aided design method useful for simulation of a set of proteolytic cleavages upon target proteins obtained from the Brookhaven Data Bank. The method was developed by using algorithms that are able to interface themselves with other software environments, in order to assist computer analyses in the molecular modelling field, and allowing the generation of molecular libraries containing protein fragments produced by simulated proteolysis. These libraries include structures that differ for several amino acid deletions upon specified regions of the primary sequence. Target residues chosen for the simulation are compatible with enzymatic proteolysis methods used in conventional laboratory procedures. Furthermore, algorithms were able to identify a set of chemical-physical properties of the starting proteins, leading the simulation to find out the most suitable residues for proteolysis. The goal of these strategies is to generate fragments that are leaded to maintain the native-like condition of starting molecules, avoiding loss of conformational characteristics of the original tertiary structure. Proteins chosen for generating proteolytic libraries were represented by naphthalene 1,2 dioxygenase and Rigidoporus lignosus laccase. 相似文献
8.
9.
Is there a role for copper in neurodegenerative diseases? 总被引:2,自引:0,他引:2
Cerpa W Varela-Nallar L Reyes AE Minniti AN Inestrosa NC 《Molecular aspects of medicine》2005,26(4-5):405-420
Copper is an essential metal in living organisms; thus, the maintenance of adequate copper levels is of vital importance and is highly regulated. Dysfunction of copper metabolism leading to its excess or deficiency results in severe ailments. Two examples of illnesses related to alterations in copper metabolism are Menkes and Wilson diseases. Several proteins are involved in the maintenance of copper homeostasis, including copper transporters and metal chaperones. In the last several years, the beta-amyloid-precursor protein (beta-APP) and the prion protein (PrP(C)), which are related to the neurodegenerative disorders Alzheimer and prion diseases respectively, have been associated with copper metabolism. Both proteins bind copper through copper-binding domains that also have been shown to reduce copper in vitro. Moreover, this ability to reduce copper is associated with a neuroprotective effect exerted by the copper-binding domain of both proteins against copper in vivo. In addition to a functional link between copper and beta-APP or PrP(C), evidence suggests that copper has a role in Alzheimer and prion diseases. Here, we review the evidence that supports both, the role of beta-APP and PrP(C), in copper metabolism and the putative role of copper in neurodegenerative diseases. 相似文献
10.
Courtney D. Fitzhugh Matthew M. Hsieh Darlene Allen Wynona A. Coles Cassie Seamon Michael Ring Xiongce Zhao Caterina P. Minniti Griffin P. Rodgers Alan N. Schechter John F. Tisdale James G. Taylor VI 《PloS one》2015,10(11)