Identification and Preliminary Clinical Validation of Key Extracellular Proteins as the Potential Biomarkers in Hashimoto's Thyroiditis by Comprehensive Analysis

Hashimoto's thyroiditis (HT) is an autoimmune disruption manifested by immune cell infiltration in thyroid tissue and the production of antibodies against thyroid-specific antigens, such as the thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb). TPOAb and TGAb are commonly used in clinical tests; however, handy indicators of the diagnosis and progression of HT are still scarce. Extracellular proteins are glycosylated and are likely to enter body fluids and become readily available and detectable biomarkers. Our research aimed to discover extracellular biomarkers and potential treatment targets associated with HT through integrated bioinformatics analysis and clinical sample validations. A total of 19 extracellular protein-differentially expressed genes (EP-DEGs) were screened by the GSE138198 dataset from the Gene Expression Omnibus (GEO) database and protein annotation databases. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze the function and pathway of EP-DEGs. STRING, Cytoscape, MCODE, and Cytohubba were used to construct a protein-protein interaction (PPI) network and screen key EP-DEGs. Six key EP-DEGs (CCL5, GZMK, CXCL9, CXCL10, CXCL11, and CXCL13) were further validated in the GSE29315 dataset and the diagnostic curves were evaluated, which all showed high diagnostic accuracy (AUC > 0.95) for HT. Immune profiling revealed the correlation of the six key EP-DEGs and the pivotal immune cells in HT, such as CD8+ T cells, dendritic cells, and Th2 cells. Further, we also confirmed the key EP-DEGs in clinical thyroid samples. Our study may provide bioinformatics and clinical evidence for revealing the pathogenesis of HT and improving the potential diagnosis biomarkers and therapeutic strategies for HT.

Extracellular proteins as potential biomarkers in Sepsis-related cerebral injury

Background

Sepsis can cause brain damage known as septic encephalopathy (SAE), which is linked to higher mortality and poorer outcomes. Objective clinical markers for SAE diagnosis and prognosis are lacking. This study aimed to identify biomarkers of SAE by investigating genes and extracellular proteins involved in sepsis-induced brain injury.

Methods

Extracellular protein differentially expressed genes (EP-DEGs) from sepsis patients' brain tissue (GSE135838) were obtained from Gene Expression Omnibus (GEO) and evaluated by protein annotation database. The function and pathways of EP-DEGs were examined using GO and KEGG. Protein-protein interaction (PPI) networks were built and crucial EP-DEGs were screened using STRING, Cytoscape, MCODE, and Cytohubba. The diagnostic and prognostic accuracy of key EP-DEGs was assessed in 31 sepsis patients' blood samples and a rat cecal ligation and puncture (CLP)-induced sepsis model. Cognitive and spatial memory impairment was evaluated 7-11 days post-CLP using behavioral tests. Blood and cerebrospinal fluid from 26 rats (SHAM n=14, CLP n=12) were collected 6 days after CLP to analyze key EP-DEGs.

Results

Thirty-one EP-DEGs from DEGs were examined. Bone marrow leukocytes, neutrophil movement, leukocyte migration, and reactions to molecules with bacterial origin were all enhanced in EP-DEGs. In comparison to the sham-operated group, sepsis rats had higher levels of MMP8 and S100A8 proteins in their venous blood (both p<0.05) and cerebrospinal fluid (p=0.0506, p<0.0001, respectively). Four important extracellular proteins, MMP8, CSF3, IL-6, and S100A8, were identified in clinical peripheral blood samples. MMP8 and S100A8 levels in the peripheral blood of sepsis patients were higher in SAE than in non-SAE. In comparison to MMP8, S100A8 had a higher area under the curve (AUC: 0.962, p<0.05) and a higher sensitivity and specificity (80% and 100%, respectively) than MMP8 (AUC: 0.790, p<0.05). High levels of S100A8 strongly correlated with 28-day mortality and the Glasgow Coma Scale (GCS) scores.

Conclusion

The extracellular proteins MMP8, CSF3, IL-6, and S100A8 may be crucial in the pathophysiology of SAE. S100A8 and MMP8 are possible biomarkers for SAE's onset and progression. This research may help to clarify the pathogenesis of SAE and improve the diagnosis and prognosis of the disease.

Regulation of σB-Dependent Biofilm Formation in Staphylococcus aureus through Strain-Specific Signaling Induced by Diosgenin

Staphylococcus aureus is a commensal skin bacterium and a causative agent of infectious diseases. Biofilm formation in S. aureus is a mechanism that facilitates the emergence of resistant strains. This study proposes a mechanism for the regulation of biofilm formation in S. aureus through strain-specific physiological changes induced by the plant steroid diosgenin. A comparison of diosgenin-induced changes in the expression of regulatory genes associated with physiological changes revealed the intracellular regulatory mechanisms involved in biofilm formation. Diosgenin reduced biofilm formation in S. aureus ATCC 6538 and methicillin-resistant S. aureus (MRSA) CCARM 3090 by 39% and 61%, respectively. Conversely, it increased biofilm formation in S. aureus ATCC 29213 and MRSA CCARM 3820 by 186% and 582%, respectively. Cell surface hydrophobicity and extracellular protein and carbohydrate contents changed in a strain-specific manner in response to biofilm formation. An assessment of the changes in gene expression associated with biofilm formation revealed that diosgenin treatment decreased the expression of icaA and spa and increased the expression of RNAIII, agrA, sarA, and sigB in S. aureus ATCC 6538 and MRSA CCARM 3090; however, contrasting gene expression changes were noted in S. aureus ATCC 29213 and MRSA CCARM 3820. These results suggest that a regulatory mechanism of biofilm formation is that activated sigB expression sequentially increases the expression of sarA, agrA, and RNAIII. This increased RNAIII expression decreases the expression of spa, a surface-associated adhesion factor. An additional regulatory mechanism of biofilm formation is that activated sigB expression decreases the expression of an unknown regulator that increases the expression of icaA. This in turn decreases the expression of icaA, which decreases the synthesis of polysaccharide intercellular adhesins and ultimately inhibits biofilm formation. By assessing strain-specific contrasting regulatory signals induced by diosgenin in S. aureus without gene mutation, this study elucidated the signal transduction mechanisms that regulate biofilm formation based on physiological and gene expression changes.

Degradation of extracellular and membrane proteins in targeted therapy: Status quo and quo vadis

Targeted protein degradation (TPD) strategies, such as proteolysis-targeting chimeras (PROTACs) only work for intracellular protein degradation because they involve the intracellular protein degradation machinery. Several new technologies have emerged in recent years for TPD of extracellular and membrane proteins. Even though some progress has been demonstrated in the extracellular and membrane protein degradation field, the application of these technologies is still in its infancy. In this review, we survey the therapeutic potential of existing technologies by summarizing and reviewing discoveries and hurdles in extracellular and membrane protein-of-interest (POI) degradation.

Improvement in hyperexpression with a combination of truncated scmp promoter and Streptomyces lividans

We have previously reported a powerful promoter from the Streptomyces cinnamoneus TH-2 strain named 'scmp' and created an expression vector of pTONA5a for expression using S. lividans. The full-length scmp promoter sequence consists of 424 bp upstream of a metalloendoprotease gene in the S. cinnamoneus TH-2 genome. The promoter works in the presence of inorganic phosphate and glucose. In this study, we present the essential region of the scmp promoter (promoter C), which lacks 358 bp of the 5' region of the full-length promoter. Promoter C was very short and contained only 63 bp. Using promoter C, we succeeded in the extracellular production of the Streptomyces enzymes of leucine aminopeptidase, ferulic acid esterase, and transglutaminase, which possessed signal peptides for secretion via the type II secretion pathway, at high levels.

Identification and Clinical Validation of Key Extracellular Proteins as the Potential Biomarkers in Relapsing-Remitting Multiple Sclerosis

Background

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) mediated by autoimmunity. No objective clinical indicators are available for the diagnosis and prognosis of MS. Extracellular proteins are most glycosylated and likely to enter into the body fluid to serve as potential biomarkers. Our work will contribute to the in-depth study of the functions of extracellular proteins and the discovery of disease biomarkers.

Methods

MS expression profiling data of the human brain was downloaded from the Gene Expression Omnibus (GEO). Extracellular protein-differentially expressed genes (EP-DEGs) were screened by protein annotation databases. GO and KEGG were used to analyze the function and pathway of EP-DEGs. STRING, Cytoscape, MCODE and Cytohubba were used to construct a protein-protein interaction (PPI) network and screen key EP-DEGs. Key EP-DEGs levels were detected in the CSF of MS patients. ROC curve and survival analysis were used to evaluate the diagnostic and prognostic ability of key EP-DEGs.

Results

We screened 133 EP-DEGs from DEGs. EP-DEGs were enriched in the collagen-containing extracellular matrix, signaling receptor activator activity, immune-related pathways, and PI3K-Akt signaling pathway. The PPI network of EP-DEGs had 85 nodes and 185 edges. We identified 4 key extracellular proteins IL17A, IL2, CD44, IGF1, and 16 extracellular proteins that interacted with IL17A. We clinically verified that IL17A levels decreased, but Del-1 and resolvinD1 levels increased. The diagnostic accuracy of Del-1 (AUC: 0.947) was superior to that of IgG (AUC: 0.740) with a sensitivity of 82.4% and a specificity of 100%. High Del-1 levels were significantly associated with better relapse-free and progression-free survival.

Conclusion

IL17A, IL2, CD44, and IGF1 may be key extracellular proteins in the pathogenesis of MS. IL17A, Del-1, and resolvinD1 may co-regulate the development of MS and Del-1 is a potential biomarker of MS. We used bioinformatics methods to explore the biomarkers of MS and validated the results in clinical samples. The study provides a theoretical and experimental basis for revealing the pathogenesis of MS and improving the diagnosis and prognosis of MS.

Induction of Rhodobacter capsulatus Gene Transfer Agent Gene Expression Is a Bistable Stochastic Process Repressed by an Extracellular Calcium-Binding RTX Protein Homologue

Bacteriophage-like gene transfer agents (GTAs) have been discovered in both of the prokaryotic branches of the three-domain phylogenetic tree of life. The production of a GTA (RcGTA) by the phototrophic alphaproteobacterium Rhodobacter capsulatus is regulated by quorum sensing and a phosphorelay homologous to systems in other species that control essential functions such as the initiation of chromosome replication and cell division. In wild-type strains, RcGTA is produced in <3% of cells in laboratory cultures. Mutants of R. capsulatus that exhibit greatly elevated production of RcGTA were created decades ago by chemical mutagenesis, but the nature and molecular consequences of the mutation were unknown. We show that the number of cells in a population that go on to express RcGTA genes is controlled by a stochastic process, in contrast to a genetic process. We used transposon mutagenesis along with a fluorescent protein reporter system and genome sequence data to identify a gene, rcc00280, that encodes an RTX family calcium-binding protein homologue. The Rc280 protein acts as an extracellular repressor of RcGTA gene expression by decreasing the percentage of cells that induce the production of RcGTA.IMPORTANCE GTAs catalyze horizontal gene transfer (HGT), which is important for genomic evolution because the majority of genes found in bacterial genomes have undergone HGT at some point in their evolution. Therefore, it is important to determine how the production of GTAs is regulated to understand the factors that modulate the frequency of gene transfer and thereby specify the tempo of evolution. This work describes a new type of genetic regulation in which an extracellular calcium-binding protein homologue represses the induction of the Rhodobacter capsulatus GTA, RcGTA.

Characterization of adhesion properties of the cardiomyocyte integrins and extracellular matrix proteins using atomic force microscopy

Integrins are transmembrane adhesion receptors that play important roles in the cardiovascular system by interacting with the extracellular matrix (ECM). However, direct quantitative measurements of the adhesion properties of the integrins on cardiomyocyte (CM) and their ECM ligands are lacking. In this study, we used atomic force microscopy (AFM) to quantify the adhesion force (peak force and mean force) and binding probability between CM integrins and three main heart tissue ECM proteins, ie, collagen (CN), fibronectin (FN), and laminin (LN). Functionalizing the AFM probes with ECM proteins, we found that the peak force (mean force) was 61.69 ± 5.5 pN (76.54 ± 4.0 pN), 39.26 ± 4.4 pN (59.84 ± 3.6 pN), and 108.31 ± 4.2 pN (129.63 ± 6.0 pN), respectively, for the bond of CN-integrin, FN-integrin, and LN-integrin. The binding specificity between CM integrins and ECM proteins was verified by using monoclonal antibodies, where α₁₀ - and α₁₁ -integrin bind to CN, α₃ - and α₅ -integrin bind to FN, and α₃ - and α₇ -integrin bind to LN. Furthermore, adhesion properties of CM integrins under physiologically high concentrations of extracellular Ca²⁺ and Mg²⁺ were tested. Additional Ca²⁺ reduced the adhesion mean force to 68.81 ± 4.0 pN, 49.84 ± 3.3 pN, and 119.21 ± 5.8 pN and binding probability to 0.31, 0.34, 0.40 for CN, FN, and LN, respectively, whereas Mg²⁺ caused very minor changes to adhesion properties of CM integrins. Thus, adhesion properties between adult murine CM integrins and its main ECM proteins were characterized, paving the way for an improved understanding of CM mechanobiology.

Elucidation of Akkermansia muciniphila Probiotic Traits Driven by Mucin Depletion

Akkermansia muciniphila is widely considered a next-generation beneficial microbe. This bacterium resides in the mucus layer of its host and regulates intestinal homeostasis and intestinal barrier integrity by affecting host signaling pathways. However, it remains unknown how the expression of genes encoding extracellular proteins is regulated in response to dynamic mucosal environments. In this study, we elucidated the effect of mucin on the gene expression and probiotic traits of A. muciniphila. Transcriptome analysis showed that the genes encoding most mucin-degrading enzymes were significantly upregulated in the presence of mucin. By contrast, most genes involved in glycolysis and energy metabolic pathways were upregulated under mucin-depleted conditions. Interestingly, the absence of mucin resulted in the upregulation of 79 genes encoding secreted protein candidates, including Amuc-1100 as well as members of major protein secretion systems. These transcript level changes were consistent with the fact that administration of A. muciniphila grown under mucin-depleted conditions to high-fat diet-induced diabetic mice reduced obesity and improved intestinal barrier integrity more efficiently than administration of A. muciniphila grown under mucin-containing conditions. In conclusion, mucin content in the growth medium plays a critical role in the improvement by A. muciniphila of high-fat diet-induced obesity, intestinal inflammation, and compromised intestinal barrier integrity related to a decrease in goblet cell density. Our findings suggest the depletion of animal-derived mucin in growth medium as a novel principle for the development of A. muciniphila for human therapeutics.

The Reissner Fiber in the Cerebrospinal Fluid Controls Morphogenesis of the Body Axis

Organ development depends on the integration of coordinated long-range communication between cells. The cerebrospinal fluid composition and flow properties regulate several aspects of central nervous system development, including progenitor proliferation, neurogenesis, and migration [1-3]. One understudied component of the cerebrospinal fluid, described over a century ago in vertebrates, is the Reissner fiber. This extracellular thread forming early in development results from the assembly of the SCO-spondin protein in the third and fourth brain ventricles and central canal of the spinal cord [4]. Up to now, the function of the Reissner fiber has remained elusive, partly due to the lack of genetic invalidation models [4]. Here, by mutating the scospondin gene, we demonstrate that the Reissner fiber is critical for the morphogenesis of a straight posterior body axis. In zebrafish mutants where the Reissner fiber is lost, ciliogenesis and cerebrospinal fluid flow are intact but body axis morphogenesis is impaired. Our results also explain the frequently observed phenotype that mutant embryos with defective cilia exhibit defects in body axis curvature. Here, we reveal that these mutants systematically fail to assemble the Reissner fiber. We show that cilia promote the formation of the Reissner fiber and that the fiber is necessary for proper body axis morphogenesis. Our study sets the stage for future investigations of the mechanisms linking the Reissner fiber to the control of body axis curvature during vertebrate development.

[Expression, purification and immunoreactivity characterization of extracellular antigenic domains of NMDAR1 protein]

This study aimed to construct prokaryotic recombinant plasmids for expression of the extracellular domains of NMDAR1 protein, purify and characterize the immunoreactivity of the recombinant proteins. Based on the mRNA sequence of human NMDAR1 gene, we predicted the structure of the antigenic domains in the extracellular part of the protein using the "phyre2" software. Primers were designed to amplify the nucleic acid fragments encoding the NMDAR1 extracellular antigenic domains by RT-PCR. The amplified gene fragments were cloned into pCold-SUMO vector to construct the recombinant plasmids which were transformed into Escherichia coli DH5α. The positive colonies harboring the recombinant plasmids were picked and verified by PCR and DNA sequencing. Then, the recombinant plasmids were transformed into E. coli BL21(DE3) strain and induced by IPTG for protein expression. The recombinant proteins were purified by Ni-NTA affinity chromatography. The target proteins were further purified by removing the 6 His-SUMO tag using enzyme excision followed by gel filtration chromatography using AKTA purifier. The purity of the recombinant proteins were evaluated by SDS-PAGE and the immunoreactivity were characterized by Western blotting. Three DNA fragments encoding the extracellular domains of NMDAR1 protein, including NR1-M1 (encoding 19-393 aa), NR1-S1 (encoding 394-544 aa) and NR1-S2 (encoding 663-800 aa), were amplified by RT-PCR. The NR1-S1 and NR1-S2 were linked with G (arginine) and T (threonine) amino acid as a combined fragment. The NR1-M1 and NR1-S1-GT-S2 fragments were cloned into pCold-SUMO vector and two recombinant plasmids, pCold-SUMO-M1 and pCold-SUMO-S1-GT-S2, were generated and expressed in E. coli. SDS-PAGE analysis showed that the recombinant plasmids expressed soluble NR1-M1 and NR1-S1-GT-S2 proteins in bacterial. After affinity chromatography and gel filtration chromatography, we obtained high purity target proteins. Western blotting assay showed that the recombinant proteins NR1-M1 and NR1-S1-GT-S2 can bind specially with their corresponding antibodies, suggesting the recombinant proteins retained antigenic reactivity. We constructed a prokaryotic expression system for expressing the NMDAR1 protein extracellular parts that had immunoreactivity successfully, and the purified proteins can be used for studying NMDAR1 function and testing the autoantibodies.

Comparison of protein expression pattern between the Plasmodium falciparum chloroquine-resistant RKL9 and chloroquine-sensitive MRC2 strains

OBJECTIVE

The objective of this study was to compare the protein expression patterns of Plasmodium falciparum extracellular and intracellular proteins separated by two-dimensional electrophoresis (2-DE) from the chloroquine-sensitive (CQS) MRC2 strain and chloroquine-resistant (CQR) RKL9 strain. Materials and Methods: Both the extracellular protein (ECP) and intracellular protein (ICP) were extracted and solubilized. The proteins were separated by 2-DE, first based on their charges using isoelectric focusing and then their sizes by electrophoresis. The separated protein spots were detected by silver staining, and further, the protein spot density was analyzed by an image analysis software.

RESULTS

2-DE separated the proteins extracted from the CQS and CQR strains based on their differentially expressed protein patterns.

EXTRACELLULAR PROTEIN ANALYSIS

A total of 109 and 77 protein spots were detected by image analysis of ECP extracted from MRC2 and RKL9 strains, respectively. There was a marked reduction in protein expression pattern in the CQR strain when compared with the CQS strain. Interestingly, 50 and 18 protein spots were uniquely expressed in MRC2 and RKL9 strains, respectively. When MRC2 strain-expressed proteins were taken as the control, 12 upregulated and 14 downregulated protein spots were observed in the RKL9 strain-extracted proteins.

INTRACELLULAR PROTEIN ANALYSIS

ICP extracted from MRC2 and RKL9 strains showed 187 and 199 protein spots by an image analysis software, and a small enhancement of protein expression was measured when comparing the CQR strain with CQS strain. There were 67 and 79 unique protein spots detected in MRC2 and RKL9 strains, respectively. A total of 120 protein spots were similar when MRC2 proteins were taken as the control; among these protein spots, 40 upregulated and 22 downregulated protein spots were detected in RKL9 strain-expressed protein.

CONCLUSIONS

Both these unique and matched protein spots might be molecularly potent drug targets for chloroquine resistance in P. falciparum. Further identification of these proteins by mass spectrometry/peptide sequencing is essential to clearly understand the mechanism of resistance.

Deorphanization of the human leukocyte tyrosine kinase (LTK) receptor by a signaling screen of the extracellular proteome

There are many transmembrane receptor-like proteins whose ligands have not been identified. A strategy for finding ligands when little is known about their tissue source is to screen each extracellular protein individually expressed in an array format by using a sensitive functional readout. Taking this approach, we have screened a large collection (3,191 proteins) of extracellular proteins for their ability to activate signaling of an orphan receptor, leukocyte tyrosine kinase (LTK). Only two related secreted factors, FAM150A and FAM150B (family with sequence similarity 150 member A and member B), stimulated LTK phosphorylation. FAM150A binds LTK extracellular domain with high affinity (K(D) = 28 pM). FAM150A stimulates LTK phosphorylation in a ligand-dependent manner. This strategy provides an efficient approach for identifying functional ligands for other orphan receptors.

The extracellular protein VlsE is destabilized inside cells

We use U2OS cells as in vivo "test tubes" to study how the same cytoplasmic environment has opposite effects on the stability of two different proteins. Protein folding stability and kinetics were compared by fast relaxation imaging, which combines a temperature jump with fluorescence microscopy of FRET (Förster resonance energy transfer)-labeled proteins. While the stability of the cytoplasmic enzyme PGK (phosphoglycerate kinase) increases in cells, the stability of the cell surface antigen VlsE, which presumably did not evolve for stability inside cells, decreases. VlsE folding also slows down more than PGK folding in cells, relative to their respective aqueous buffer kinetics. Our FRET measurements provide evidence that VlsE is more compact inside cells than in aqueous buffer. Two kinetically distinct protein populations exist inside cells, making a connection with previous in vitro crowding studies. In addition, we confirm previous studies showing that VlsE is stabilized by 150mg/mL of the carbohydrate crowder Ficoll, even though it is destabilized in the cytoplasm relative to aqueous buffer. We propose two mechanisms for the observed destabilization of VlsE in U2OS cells: long-range interactions competing with crowding or shape-dependent crowding favoring more compact states inside the cell over the elongated aqueous buffer native state.

Computational prediction of O-linked glycosylation sites that preferentially map on intrinsically disordered regions of extracellular proteins

O-glycosylation of mammalian proteins is one of the important posttranslational modifications. We applied a support vector machine (SVM) to predict whether Ser or Thr is glycosylated, in order to elucidate the O-glycosylation mechanism. O-glycosylated sites were often found clustered along the sequence, whereas other sites were located sporadically. Therefore, we developed two types of SVMs for predicting clustered and isolated sites separately. We found that the amino acid composition was effective for predicting the clustered type, whereas the site-specific algorithm was effective for the isolated type. The highest prediction accuracy for the clustered type was 74%, while that for the isolated type was 79%. The existence frequency of amino acids around the O-glycosylation sites was different in the two types: namely, Pro, Val and Ala had high existence probabilities at each specific position relative to a glycosylation site, especially for the isolated type. Independent component analyses for the amino acid sequences around O-glycosylation sites showed the position-specific existences of the identified amino acids as independent components. The O-glycosylation sites were preferentially located within intrinsically disordered regions of extracellular proteins: particularly, more than 90% of the clustered O-GalNAc glycosylation sites were observed in intrinsically disordered regions. This feature could be the key for understanding the non-conservation property of O-glycosylation, and its role in functional diversity and structural stability.

Extracellular proteins as enterobacterial thermometers

Biological thermometers are cellular components or structures which sense increasing temperatures, interaction of the thermometer and the thermal stress bringing about the switching-on of inducible responses, with gradually enhanced levels of response induction following gradually increasing temperatures. In enterobacteria, for studies of such thermometers, generally induction of heat shock protein (HSP) synthesis has been examined, with experimental studies aiming to establish (often indirectly) how the temperature changes which initiate HSP synthesis are sensed; numerous other processes and responses show graded induction as temperature is increased, and how the temperature changes which induce these are sensed is also of interest. Several classes of intracellular component and structure have been proposed as enterobacterial thermometers, with the ribosome and the DnaK chaperone being the most favoured, although for many of the proposed intracellular thermometers, most of the evidence for their functioning in this way is indirect. In contrast to the above, the studies reviewed here firmly establish that for four distinct stress responses, which are switched-on gradually as temperature increases, temperature changes are sensed by extracellular components (extracellular sensing components, ESCs) i.e. there is firm and direct evidence for the occurrence of extracellular thermometers. All four thermometers described here are proteins, which appear to be distinct and different from each other, and on sensing thermal stress are activated by it to four distinct extracellular induction components (EICs), which interact with receptors on the surface of organisms to induce the appropriate responses. It is predicted that many other temperature-induced processes, including the synthesis of HSPs, will be switched-on following the activation of similar extracellular thermometers by thermal stimuli.