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| Concept of Toxicoproteomics in Identifying Biomarkers of Toxicant Action |
| Yogeshwer Shukla |
| Proteomics Laboratory, Indian Institute of Toxicology Research (CSIR), Mahatma Gandhi Marg, P.O.Box 80, Lucknow-226001, India |
| *Corresponding author: |
Yogeshwer Shukla
Proteomics Laboratory
Indian
Institute of Toxicology Research (CSIR)
Mahatma Gandhi Marg, P.O.Box 80,
Lucknow-226001, India
E-mail: yogeshwer_shukla@hotmail.com |
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| Received December 08, 2011; Accepted December 10, 2011; Published December 14, 2011 |
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| Citation: Shukla Y (2011) Concept of Toxicoproteomics in Identifying Biomarkers
of Toxicant Action. J Proteomics Bioinform 4: vi-vii. doi:10.4172/jpb.100000e7 |
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| Copyright: © 2011 Shukla Y. This is an open-access article distributed under the
terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited. |
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| Humans are often exposed to a variety of environmental toxicants
that contribute to an individual’s risk for disease. Therefore, in
toxicological research new approaches are required for effective
screening of environmental risks on complex living systems. Laboratory
data generated through several in vitro, in vivo and some clinical studies
have supported that various environmental products produce a broad
spectrum of adverse health effects including neurological disorders
and cancer. However, the results of these studies are still contentious;
nevertheless, their mechanism of action is clear. For identification
of molecular signatures and methodical understandings of
various environmental toxicants response in biological systems,
toxicoproteomics is considered to be a valued approach. The cellular
response to carcinogens/toxicants is complex, so to maintain genomic
stability and prevent carcinogenesisthe network of events taking place
in the cell needs to be determined and abundant efforts has been put in
for this. There are well over 10,000 publications relating to applications
of proteomics in the toxicology research. Toxicoproteomics has been
enhanced by tools from proteomics, bioinformatics and other enabling
high data technologies. |
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| Today, toxicoproteomics mainly relies on high throughput
technique 2-dimensional gel electrophoresis (2-DE) coupled with
mass spectrometry (MS) for separation, detection and identification
of proteins, which might illustrate a certain state of disease, specify
toxicity or even forecast carcinogenicity.Fluorescent dyes such as Sypro
ruby has been the most sensitive means of protein detection (nanoto
microgram range) in recent past.Latest development of modern
techniques for instance multiplex fluorescence coloring using the
differential gel electrophoresis (DIGE) provides a more detailed gel-togel
comparison and quantification of proteins separated by 2-DE. Still,
there are enduring apprehensions regarding the standardization
of electrophoresis protocols, the reproducibility of the data, and the
subjective nature of 2-DE gel image analysis. Therefore, alternative
proteomics methodologies, such as liquid chromatography (LC-MS/
MS) and surface-enhanced laser desorption ionization time-of-flight
mass spectrometry (SELDI-TOF-MS), are pretty more prevalent in
clinical medicine and very currently in environmental toxicology.
Other disparities on the LC-MS/MS method, closely linking LC
separation to MS/MS instruments, have unified isotopic labelling
approaches for protein quantitation and in-depth proteomic profiling
of samples. Examples of such platforms are isotope coded affinity tags
(ICAT), isobaric tag for relative and absolute quantitation (iTRAQ)
and stable isotope labelling with amino acids in cell culture (SILAC). |
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| Midst of numerous environmental toxicants, pesticides,
used widely for controlling pest and destroying weeds are global
contaminants accumulating in our environment and hence humans
get unavoidably exposed to these pesticides. Organophosphates,
pyrethroids and carbamates, some of the extensively used group
of pesticides, have been informed to possess carcinogenic and cocarcinogenic
potential in various test systems. We can use biomarkers
to distinguish fundamental links and to make better quantifiable
estimations of those links at relevant levels of exposure and this will enable us to expand our understanding of mechanism behind their
carcinogenic potential. Studies from our laboratory, demonstrated
the usefulness of toxicoproteomics technology in identification of
pesticides-inducing neoplastic changes in mammalian skin system.
Using this approach, we attempted to identify that SOD 1, calcyclin
(S100A6) and calgranulin-B (S100A9) are associated with glyphosate
(organophosphate herbicide) inducing tumor promoting potential
and may be useful as biomarkers for tumor promotion. We also utilize
2-DE and MS in studying the molecular mechanism that contributes
in mancozeb (carbamate fungicide)-induced carcinogenesis. The level
of S100A6 and S100A9 was significantly up regulated in the mancozeb
exposed mouse skin and later found to be higher in mancozeb-exposed
human keratinocytes, HaCaTcells. Furthermore, using quantitative
proteomics in mouse skin exposed to cypermethrin, a synthetic
pyrethroid insecticide, we reported 7 proteins (carbonic anhydrase 3,
Hsp-27, S100A6,galectin-7, S100A9, S100A11, SOD 1) play significant
roles in many cellular functions, including oxidative stress response,
proliferation, binding of calcium ions and apoptosis. Commotion of
these processes plays a vital role in carcinogenesis. Hence supports
that these proteins were allied with induction of cell proliferation and
might be responsible for the neoplastic transformation of mouse skin
preneoplastic lesions by cypermethrin. |
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| Toxicoproteomic platform could be easily used for biomarker
identification for numerous environmental stressors as most of the
biological changes occur at proteome level like post translational
modifications. A number of laboratories globally are now directing
their attention on application of this platform and emerging data
is accumulating for biomarker development, studying underlying
mechanistic pathways and suitable risk assessment against many
toxicants action. Though, toxicoproteomic technology's incessant
progress exclusively cannot elucidate the successive steps of pesticideinduced
carcinogenesis. Synergistic research efforts comprising the
study of metabolic activation of chemicals, genome analysis, mRNA
measurements, classical biochemical analysis, and data analysis and
classification are a must. Additional modifications of MS/MS with
closely integrated multi-dimensional separation schemes will continue
to dominate proteomic analysis for identification and quantification
and will result in following developments. MS instruments and
software will become more user-friendly and accessible, such as the
recently introduced orbitrap MS/MS instruments along with the “reduction of sample complexity” or any prepurification strategy
prior to toxicoproteomics analysis will be very useful upon innovative
application to appropriate biological samples and problem areas (i.e.,
immunodepletion of high abundance proteins like albumin or immune
globulins in plasma) or research problem areas (i.e., phosphoprotein
enrichment in protein signalling). Likewise, Tier II proteomics will
begin to be applied totoxicoproteomics problem areas such as global
and targeted protein phosphorylation and chemoproteomics using
pharmaceutics or enzyme substrates like ATP as mass captureligands
for proteins. Similarly, toxicoproteomics is readily positioned
to exploit accessible biofluids (i.e., serum/plasma, urine and cerebral
spinal fluid) for biomarker development and could be combined with transcriptomic analysis of blood leukocytes for a parallel approach
in biomarker discovery and also the incisive use of genetically
transformed animals and cell models will improve discovery of protein
targets and mechanistic insights into adverse drug reactions. Lastly,
continued efforts for integration of proteomics, transcriptomics and
toxicology data to derive mechanistic insight and biomarkers will be
a continuing goal to maximize return on the investment in Omics
technologies. While there are many challenges for toxicoproteomics
in preclinical valuation, the chances are also close at hand for a
superior understanding of toxicant action, the association to associated
dysfunction and pathology, and the growth of predictive biomarkers
and signatures of toxicity. |
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