Array Of Biological Responses Research Articles

Sequence analysis of the cDNA encoding for SpCTx: a lethal factor from scorpionfish venom (Scorpaena plumieri)

BackgroundLethal factors are multifunctional oligomeric proteins found in the venomous apparatus of Scorpaeniformes fish. These toxins elicit not only an array of biological responses in vitro but also cardiovascular disorders and strong hemolytic, nociceptive and edematogenic activities in vivo. This work describes the cloning and molecular identification of two toxin subunits, denominated Sp-CTx-α and Sp-CTx-β, from scorpionfish venom (Scorpaena plumieri).MethodsThe primary structures were deduced after cDNA amplification by PCR with primers from conserved sequences described in Scorpaeniformes toxins. Following DNA sequencing and bioinformatic analysis, the tridimensional structures of both subunits were modeled.ResultsThe translated sequences (702 amino acids, each subunit) show homology with other lethal factors, while alignment between Sp-CTx-α and Sp-CTx-β shows 54% identity. The subunits lack N-terminal signal sequences and display masses of approximately 80 kDa each. Both Sp-CTx subunits display a B30.2/SPRY domain at the C-terminal region with typically conserved motifs as described in these toxins. Secondary structure prediction identified six α-helices 18 residues long in both α and β subunits, some of them amphiphilic with their N-terminal flanked by many basic residues, creating a cationic site associated with the cytolytic activity of these toxins. Antimicrobial potential sites were identified in Sp-CTx and share some features with other peptides presenting variable and broad-spectrum activity. A phylogenetic tree built to represent these toxins supports the proximity between scorpionfish, lionfish and stonefish.ConclusionThe study identified a putative toxin protein whose primary structure is similar to other fish toxins and with potential for production of antivenom against scorpionfish envenomation in Brazil. As a prelude to structure-function studies, we propose that the toxin is structurally related to pore-forming marine toxins.

Unveiling the Impact of Distinct Melanosome Arrangements on the Attenuation of Cancer-Inducing Ultraviolet Radiation.

The exposure of human skin to ultraviolet radiation (UVR) can trigger a wide array of biological responses, including photocarcinogenesis. Melanin, either in colloidal form or encapsulated into melanosomes, is known to be the main UVR attenuation substance acting within the cutaneous tissues. Although many studies have addressed the protective role of this pigment against the harmful effects of UVR exposure, the impact of different melanosome arrangements on the mitigation of these effects remains to be quantitatively verified. The difficulties to resolve this open question can be mainly attributed to the intrinsic practical limitations of in vivo and in vitro experiments involving skin specimens. In this paper, we describe controlled in silico experiments that allowed us to overcome such limitations and provide quantitative evidence for the clarification of this question. Besides contributing to a more robust understanding of the physiological parameters associated with cutaneous UVR attenuation, our findings can be incorporated into the development of more effective strategies for the evaluation of individuals' susceptibility to UVR exposure. Such strategies are essential for the prevention of UVR-induced pathologies, particularly skin cancer.

Abstract 218: Functional proteomic analysis of TβRI immunocomplex in TGF-β signaling

Abstract Transforming growth factor-beta (TGF-β) regulates a wide array of biological responses ranging from proliferation to apoptosis, and alterations in its signaling pathway are associated with a variety of human diseases, including cancer. During the activation of TGF-β signaling, TGF-β receptor I (TβRI) plays an important role in transducing signals to downstream effectors. To identify TβRI interacting proteins which are responsible for Smad-dependent pathways as well as Smad-independent pathways, we employed a large-scale quantitative proteomic analysis of TβRI immunocomplex. AML12 cells were labeled with L-Lysine and L-Arginine (K0R0, light) or L-Lysine-13C6-15N2 and L-Arginine-U-13C6-15N4 (K8R10, heavy). The cells cultured in K8R10 medium (H: Heavy) were transfected with Flag-TβRI, while the cells cultured in K0R0 medium (L: Light) were transfected with Flag vector. The cell lysates were combined at equal protein amount, and TβRI immunocomplex were purified using FLAG M2 agarose. The resulting peptides from eluted TβRI immunocomplex were subjected to mass spectrometry quantitation. If a protein whose ratio of H/L was not smaller than 1.3, it was categorized as a constitutively interacting protein of TβRI. A total of 687 proteins were quantitated and 325 proteins were defined as constitutively interacting proteins. Pathway enrichment analysis found these proteins are involved in a number of signaling pathways, which indicates the cross-talks between TGF-β signaling and other signaling. Future work will include validation of interaction between TβRI and candidate proteins, and understand functional significance of candidate proteins in TGF-β signaling or signaling cross-talks by a series of molecular biological approaches. Citation Format: Liuya Tang, Zhaojing Meng, Mary Heller, Ming Zhou, Ying Zhang. Functional proteomic analysis of TβRI immunocomplex in TGF-β signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 218. doi:10.1158/1538-7445.AM2017-218

The Imprint of Extreme Climate Events in Century-Long Time Series of Wood Anatomical Traits in High-Elevation Conifers.

Extreme climate events are of key importance for forest ecosystems. However, both the inherent infrequency, stochasticity and multiplicity of extreme climate events, and the array of biological responses, challenges investigations. To cope with the long life cycle of trees and the paucity of the extreme events themselves, our inferences should be based on long-term observations. In this context, tree rings and the related xylem anatomical traits represent promising sources of information, due to the wide time perspective and quality of the information they can provide. Here we test, on two high-elevation conifers (Larix decidua and Picea abies sampled at 2100 m a.s.l. in the Eastern Alps), the associations among temperature extremes during the growing season and xylem anatomical traits, specifically the number of cells per ring (CN), cell wall thickness (CWT), and cell diameter (CD). To better track the effect of extreme events over the growing season, tree rings were partitioned in 10 sectors. Climate variability has been reconstructed, for 1800–2011 at monthly resolution and for 1926–2011 at daily resolution, by exploiting the excellent availability of very long and high quality instrumental records available for the surrounding area, and taking into account the relationship between meteorological variables and site topographical settings. Summer temperature influenced anatomical traits of both species, and tree-ring anatomical profiles resulted as being associated to temperature extremes. Most of the extreme values in anatomical traits occurred with warm (positive extremes) or cold (negative) conditions. However, 0–34% of occurrences did not match a temperature extreme event. Specifically, CWT and CN extremes were more clearly associated to climate than CD, which presented a bias to track cold extremes. Dendroanatomical analysis, coupled to high-quality daily-resolved climate records, seems a promising approach to study the effects of extreme events on trees, but further investigations are needed to improve our comprehension of the critical role of such elusive events in forest ecosystems.

G Proteins, p60TRP, and Neurodegenerative Diseases

Alzheimer's disease (AD) is a complex brain disorder of the limbic system and association cortices. The disease is characterized by the production and deposition of the amyloid β-peptide (Aβ) in the brain, and the neuropathological mechanisms involved must be deciphered to gain further insights into the fundamental aspects of the protein biology responsible for the development and progression of this disease. Aβ is generated by the intramembranous cleavage of the β-amyloid precursor protein, which is mediated by the proteases β- and γ-secretase. Accumulating evidence suggests the importance of the coupling of this cleavage mechanism to G protein signaling. Heterotrimeric G proteins play pivotal roles as molecular switches in signal transduction pathways mediated by G protein-coupled receptors (GPCRs). Extracellular stimuli activate these receptors, which in turn catalyze guanosine triphosphate-guanosine diphosphate exchange on the G protein α-subunit. The activation-deactivation cycles of G proteins underlie their crucial functions as molecular switches for a vast array of biological responses. The novel transcription regulator protein p60 transcription regulator protein and its related GPCR signaling pathways have recently been described as potential targets for the development of alternative strategies for inhibiting the early signaling mechanisms involved in neurodegenerative diseases such as AD.

How GPCRs hit the switch

The activation-deactivation cycles of G proteins underlie their key roles as molecular switches for a vast array of biological responses. A study in this issue obtains a first look at how G protein–coupled receptors activate heterotrimeric G proteins to switch on signaling pathways by inducing a specific conformational change within their α subunits.

Vitamin D3—ein Prodrug verschiedener D3-Hormone

Vitamin D (Colecalciferol) ist wahrend des gesamten Lebens fur die Knochengesundheit von auserordentlicher Bedeutung. Vitamin D wird konsekutiv in der Leber in 25-Hydroxy-colecalciferol sowie in der Niere in 1α,25-25-Dihydroxy-colecalciferol (Calcitriol) uberfuhrt. Calcitriol ist das dominierende D3-Hormon, das eine grose Anzahl biologischer Effekte durch Angriff am klassischen nuklearen Vitamin-D-Rezeptor (VDRnuc) induziert. Es reguliert die Gentranskription in uber 30 Zielorganen. Calcitriol interagiert auch mit einem putativ zellmembranstandigen Rezeptor (VDRmem1,25) der fur schnelle biologische Antworten verantwortlich ist. 24R,25-Dihydroxy-colecalciferol ist als ein weiteres Hormon fur die Frakturheilung von essentieller Bedeutung. Es entfaltet seine biologischen Effekte durch stereospezifischen Angriff an einem zweiten membranstandigen Rezeptor, VDRmem24,25 Ein weiteres D3-Hormon, das fur die Regulation der Zellproliferation in der Prostata von zentraler Bedeutung ist, ist 25-Hydroxy-colecalciferol. Es wirkt hauptsachlich durch direkten Angriff am nuklearen Vitamin-D-Rezeptor, z. T. jedoch auch durch seine 1α-Hydroxylierung in der Prostata. Altere Menschen haben haufig wahrend des gesamten Jahres einen Mangel an 25-Hydroxy-colecalciferol. Eine Supplementierung mit taglich 400 IE Vitamin D ist erforderlich, um adaquate 25-Hydroxy-colecalciferol-Spiegel zu erzielen.

Tissue-specific regulation by vitamin D status of nuclear and mitochondrial gene expression in kidney and intestine.

Vitamin D is responsible, through the actions of its metabolite, 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3], for the generation of a wide array of biological responses, particularly in the intestine, kidney, and bone. 1 alpha,25-(OH)2D3 is known to interact with its nuclear receptor to mediate the regulation of gene transcription. Although many genes and gene products have been shown to be regulated by 1 alpha,25-(OH)2D3 (e.g. calbindin-D28K in the intestine and kidney; collagen, osteocalcin,and osteopontin in bone), their recognition has been largely the result of empirical testing. In this report we have used subtractive hybridization analysis of complementary DNA libraries prepared from messenger RNA (mRNA) isolated from the intestine and kidney of vitamin D-replete or vitamin D-deficient chicks to identify genes for novel proteins whose steady state mRNA levels are regulated by dietary vitamin D status. In the kidney we observed the down-regulated expression of at least seven mitochondrially encoded transcripts and the up-regulated expression of five nuclear encoded genes, two of which are metallothionein and the beta-subunit of aldolase. In the intestine, six mitochondrially encoded transcripts are up-regulated, and seven nuclear encoded transcripts were either up- or down-regulated. Thus, in addition to identifying new nuclear encoded genes whose mRNAs are regulated by vitamin D status, our approach has demonstrated the tissue-specific regulation of mitochondrial gene expression in the intestine and kidney.