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PubMed2026

Comparative toxicoproteomics reveals distinct proteostasis and ribosomal stress signatures of CMIT and PHMG.

Methylchloroisothiazolinone (CMIT) and polyhexamethylene guanidine (PHMG) are antimicrobial biocides associated with pulmonary toxicity, although their comparative cellular stress mechanisms remain unclear. Here, we investigated how CMIT and PHMG differentially alter the proteome of human alveolar epithelial A549 cells under subcytotoxic conditions. Cells were exposed to CMIT or PHMG, and global proteomic profiling was performed using label-free liquid chromatography-tandem mass spectrometry. Differentially expressed proteins (DEPs) were identified at a 1% false discovery rate with an absolute log2 fold change ≥1. Functional analyses were conducted using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Ingenuity Pathway Analysis, and selected proteins were validated by western blotting. Comparative toxicoproteomics revealed distinct stress-response signatures induced by the two biocides. CMIT preferentially altered proteins associated with proteostasis, oxidative stress, and protein quality control, whereas PHMG was characterized by coordinated depletion of ribosome-associated and translation-related proteins. A total of 73 and 155 DEPs were identified in CMIT- and PHMG-treated cells, respectively, with 22 proteins shared between treatments. Western blotting confirmed PSMD3, TUBB2A, and GLRX1 as CMIT-responsive proteins and THRAP3, DHX15, and RPL4 as PHMG-responsive markers. These findings provide comparative mechanistic insight into how CMIT and PHMG induce distinct epithelial stress responses and identify candidate protein markers that may support future in vitro assessment of biocide-induced pulmonary toxicity.

CMIT↗
PubMed2005

Some features associated with organosilane groups grafted by the sol-gel process onto synthetic talc-like phyllosilicate.

Two new lamellar inorganic-organic magnesium silicates have been successfully synthesized by using sol-gel based processes under mild temperature conditions. The talc-organosilicates derived using two silylating agents as the silicon source, (i) 3-chloropropyltrimethoxysilane, and (ii) from the attachment of 5-amino-1,3,4-thiadiazole-2-thiol molecule to this precursor agent, yielded PhMg-Cl and PhMg-Tz phyllosilicates. These organoclays were characterized through elemental analyses, infrared spectroscopy, X-ray diffractometry, surface area, thermogravimetry, and carbon and silicon solid state nuclear magnetic resonance spectroscopy. The results confirmed the presence of organic moieties covalently bonded to the inorganic silicon sheet network of the 2:1 class of phyllosilicates, with a density of organic molecules of 6.6+/-0.1 and 2.7+/-0.2 mmol g(-1) anchored on the inorganic layer and with interlayer distances of 1158 and 1628 pm, respectively. The nuclear magnetic resonances results in the solid state are in agreement with the sequence of carbons distributed in the pendant chains of the original silylating agents and the silicon bonded to oxygen atoms or carbon atoms of the inorganic sheets, as expected for the organically functionalized phyllosilicates. The enhanced potential of the new compound PhMg-Tz as a multi property material was explored in adsorbing cations from aqueous solution. The basic sulfur and nitrogen centers attached to the pendant chains inside the lamellar cavity can coordinate mercury, by presenting an isotherm saturated at 0.19 mmol g(-1) of this heavy metal. The functionality of this organoclay-like material expresses its potential for heavy cation removal from an ecosystem.

Journal Article↗
PubMed1998

Selective loss of mouse embryos due to the expression of transgenic major histocompatibility class I molecules early in embryogenesis.

Among the numerous hypotheses proposed to explain the absence of fetal rejection by the mother in mammals, it has been suggested that regulation of expression of the polymorphic major histocompatibility complex (MHC) at the fetal-maternal interface plays a major role. In addition to a lack of MHC gene expression in the placenta throughout gestation, the absence of polymorphic MHC molecules on the early embryo, as well as their low level of expression after midgestation, could contribute to this important biologic phenomenon. In order to test this hypothesis, we have produced transgenic mice able to express polymorphic MHC class I molecules early in embryogenesis. We have placed the MHC class la gene H-2Kb under the control of a housekeeping gene promoter, the hydroxy-methyl-glutaryl coenzyme A reductase (HMG) gene minimal promoter. This construct has been tested for functionality after transfection into mouse fibroblast L cells. The analysis of three founder transgenic mice and their progeny suggested that fetoplacental units that could express the H-2Kb heavy chains are unable to survive in utero beyond midgestation. We have shown further that a much higher resorption rate, on days 11 to 13 of embryonic development, is observed among transgenic embryos developing from eggs microinjected at the one-cell stage with the pHMG-Kb construct than in control embryos. This lethality is not due to immune phenomena, since it is observed in histocompatible combinations between mother and fetus. These results are discussed in the context of what is currently known about the regulation of MHC expression at the fetal-maternal interface and in various transgenic mouse models.

Animals↗
PubMed2004

The homogentisate pathway: a central catabolic pathway involved in the degradation of L-phenylalanine, L-tyrosine, and 3-hydroxyphenylacetate in Pseudomonas putida.

Pseudomonas putida metabolizes Phe and Tyr through a peripheral pathway involving hydroxylation of Phe to Tyr (PhhAB), conversion of Tyr into 4-hydroxyphenylpyruvate (TyrB), and formation of homogentisate (Hpd) as the central intermediate. Homogentisate is then catabolized by a central catabolic pathway that involves three enzymes, homogentisate dioxygenase (HmgA), fumarylacetoacetate hydrolase (HmgB), and maleylacetoacetate isomerase (HmgC), finally yielding fumarate and acetoacetate. Whereas the phh, tyr, and hpd genes are not linked in the P. putida genome, the hmgABC genes appear to form a single transcriptional unit. Gel retardation assays and lacZ translational fusion experiments have shown that hmgR encodes a specific repressor that controls the inducible expression of the divergently transcribed hmgABC catabolic genes, and homogentisate is the inducer molecule. Footprinting analysis revealed that HmgR protects a region in the Phmg promoter that spans a 17-bp palindromic motif and an external direct repetition from position -16 to position 29 with respect to the transcription start site. The HmgR protein is thus the first IclR-type regulator that acts as a repressor of an aromatic catabolic pathway. We engineered a broad-host-range mobilizable catabolic cassette harboring the hmgABC, hpd, and tyrB genes that allows heterologous bacteria to use Tyr as a unique carbon and energy source. Remarkably, we show here that the catabolism of 3-hydroxyphenylacetate in P. putida U funnels also into the homogentisate central pathway, revealing that the hmg cluster is a key catabolic trait for biodegradation of a small number of aromatic compounds.

Bacterial Proteins↗