The Effect of an Authentic Acute Physical Education Session of Dance on Elementary Students' Selective Attention.

There have been calls to test the potential benefits of different forms of physical activity (PA) to executive function, particularly in authentic settings. Hence, the purpose of this study was to investigate the effect of an acute dance session within an existing physical education class on students' selective attention. The study employed a pre/posttest quasi-experimental design with a comparison group in one Aotearoa, New Zealand, primary school. Participants were 192 students (comparison group = 104 students) in Years 5 and 6. The intervention group participated in a dance-based physical education lesson while the comparison group continued their regular classroom work. PA during the physical education lesson was monitored using accelerometers. Selective attention was assessed at pretest and after the comparison/physical education sessions with the d2 Test of Attention. 2 × 2 ANOVA results suggested a significant time effect for all three measures, no significant group effects for any measures, and significant time by group interactions for TN and CP but not for E%. The intervention group improved significantly more than the comparison group for TN and CP. This study's findings suggest that existing school opportunities focused on cognitively engaging PA, such as dance, can improve aspects of students' selective attention.

Transcriptional activity of the SHP-1 gene in MCF7 cells is differentially regulated by binding of NF-Y factor to two distinct CCAAT-elements.

Our previous studies have shown that SHP-1, a SH2 domain-containing protein-tyrosine phosphatase, is expressed not only in cells of hematopoietic lineages, but also in many non-hematopoietic cells under the control of an alternative tissue-specific promoter, P1. In this study, the activity of the P1 promoter was analyzed in a region spanning 3.5 kb upstream of the major transcription start site in non-hematopoietic MCF-7 cells. Using DNA footprinting, gel retardation assays and mutational analysis, we have characterized cis-regulatory elements that are essential to confer the P1 promoter activity. An upstream Sp1 element (-126 to -118) positively regulated this TATA-box-lacking promoter. Two inverted CCAAT-elements (-332 to -328 and -66 to -62) played important roles in regulating the SHP-1 gene expression, and transcription factor NF-Y predominantly bound to the two CCAAT-elements. Binding of NF-Y to the distal CCAAT-element enhanced the transcriptional activity of the P1 promoter. In contrast, binding of NF-Y to the proximal CCAAT-element and interacting with repressor(s) inhibited the promoter activity. Furthermore, incubation of MCF7 cells with 100 ng/ml trichostatin A, an inhibitor of histone deacetylase, significantly increased the activity of the P1 promoter. Mutation in the proximal CCAAT-element, however, eliminated the activating effect of trichostatin A on the promoter. Together, our data suggest that NF-Y factor can function either as a specific positive or negative regulator of P1 promoter activity in non-hematopoietic MCF7 cells.

Identification and characterization of S2V, a novel putative siglec that contains two V set Ig-like domains and recruits protein-tyrosine phosphatases SHPs.

We describe the molecular cloning and characterization of S2V, a novel sialic acid binding immunoglobulin-like lectin. The cDNA of S2V encodes a type 1 transmembrane protein with four extracellular immunoglobulin-like (Ig-like) domains and a cytoplasmic tail bearing a typical immunoreceptor tyrosine-based inhibitory motif (ITIM) and an ITIM-like motif. A unique feature of S2V is the presence of two V-set Ig-like domains responsible for the binding to sialic acid, whereas all other known siglecs possess only one. S2V is predominantly expressed in macrophage. In vivo S2V was tyrosine-phosphorylated when co-expressed with exogenous c-Src kinase. Upon tyrosine phosphorylation, S2V recruits both Src homology 2 (SH2) domain-containing protein-tyrosine phosphatases SHP-1 and SHP-2, two important inhibitory regulators of immunoreceptor signal transduction. These findings suggest that S2V is involved in the negative regulation of the signaling in macrophage by functioning as an inhibitory receptor. When expressed in COS-7 cells, S2V was able to mediate sialic acid-dependent binding to human red blood cells, suggesting that S2V may function through cell-cell interaction.

mSiglec-E, a novel mouse CD33-related siglec (sialic acid-binding immunoglobulin-like lectin) that recruits Src homology 2 (SH2)-domain-containing protein tyrosine phosphatases SHP-1 and SHP-2.

The sialic acid-binding immunoglobulin-like lectins (siglecs) represent a recently defined distinct subset of the immunoglobulin superfamily. By using the Src homology 2 (SH2)-domain-containing protein tyrosine phosphatase SHP-1 as bait in a yeast two-hybrid screen, we have identified a new member of the mouse siglec family, mSiglec-E. The mSiglec-E cDNA encodes a protein of 467 amino acids that contains three extracellular immunoglobulin-like domains, a transmembrane region and a cytoplasmic tail bearing two immunoreceptor tyrosine-based inhibitory motifs (ITIMs). mSiglec-E is highly expressed in mouse spleen, a tissue rich in leucocytes. The ITIMs of mSiglec-E can recruit SHP-1 and SHP-2, two inhibitory regulators of immunoreceptor signal transduction. This suggests that the function of mSiglec-E is probably an involvement in haematopoietic cells and the immune system as an inhibitory receptor. When expressed in COS-7 cells, mSiglec-E was able to mediate sialic acid-dependent binding to human red blood cells, suggesting that mSiglec-E may function through cell-cell interactions. In comparison with the known members of the siglec family, mSiglec-E exhibits a high degree of sequence similarity to both human siglec-7 and siglec-9. The gene encoding mSiglec-E is localized in the same chromosome as that encoding mouse CD33. Phylogenetic analysis reveals that neither mouse mSiglec-E nor CD33 shows a clear relationship with any human siglecs so far identified.

The discovery of non-basic atrial natriuretic peptide clearance receptor antagonists. Part 1.

The cyclic peptide ANP 4-23 and the linear peptide analogue AP-811 have been shown to be selective ANP-CR antagonists. Via alanine scanning and truncation studies we sought to determine which residues in these molecules were important in their binding to the clearance receptor and the relationship between these two molecules. These studies show that several modifications to these compounds are possible which improve physical properties of these molecules while retaining high affinity for the ANP-CR.

PILRalpha, a novel immunoreceptor tyrosine-based inhibitory motif-bearing protein, recruits SHP-1 upon tyrosine phosphorylation and is paired with the truncated counterpart PILRbeta.

SHP-1-mediated dephosphorylation of protein tyrosine residues is central to the regulation of several cell signaling pathways, the specificity of which is dictated by the intrinsic affinity of SH2 domains for the flanking sequences of phosphotyrosine residues. By using a modified yeast two-hybrid system and SHP-1 as bait, we have cloned a human cDNA, PILRalpha, encoding a 303-amino acid immunoglobulin-like transmembrane receptor bearing two cytoplasmic tyrosines positioned within an immunoreceptor tyrosine-based inhibitory motif. Substrate trapping in combination with pervanadate treatment of 293T cells confirms that PILRalpha associates with SHP-1 in vivo upon tyrosine phosphorylation. Mutation of the tyrosine residues in PILRalpha indicates the pivotal role of the Tyr-269 residue in recruiting SHP-1. Surface plasmon resonance analysis further suggests that the association between PILRalpha-Tyr-269 and SHP-1 is mediated primarily via the amino-terminal SH2 domain of the latter. Polymerase chain reaction amplification of cDNA in combination with genomic sequence analysis revealed a second gene, PILRbeta, coding for a putative activating receptor as suggested by a truncated cytoplasmic tail and a charged lysine residue in its transmembrane region. The PILRalpha and PILRbeta genes are localized to chromosome 7 which is in contrast with the mapping of known members of the inhibitory receptor superfamily.

ZRP-1, a zyxin-related protein, interacts with the second PDZ domain of the cytosolic protein tyrosine phosphatase hPTP1E.

Protein-protein interactions play an important role in the specificity of cellular signaling cascades. By using the yeast two-hybrid system, a specific interaction was identified between the second PDZ domain of the cytosolic protein tyrosine phosphatase hPTP1E and a novel protein, which was termed ZRP-1 to indicate its sequence similarity to the Zyxin protein family. The mRNA encoding this protein is distributed widely in human tissues and contains an open reading frame of 1428 base pairs, predicting a polypeptide of 476 amino acid residues. The deduced protein displays a proline-rich amino-terminal region and three double zinc finger LIM domains at its carboxyl terminus. The specific interaction of this novel protein with the second PDZ domain of hPTP1E was demonstrated both in vitro, using bacterially expressed proteins, and in vivo, by co-immunoprecipitation studies. Deletion analysis indicated that an intact carboxyl terminus is required for its interaction with the second PDZ domain of hPTP1E in the yeast two-hybrid system and suggested that other sequences, including the LIM domains, also participate in the interaction. The genomic organization of the ZRP-1 coding sequence is identical to that of the lipoma preferred partner gene, another Zyxin-related protein, suggesting that the two genes have evolved from a recent gene duplication event.

Fusion proteins could generate false positives in peptide phage display.

Fusion proteins are frequently used in the functional characterization of newly discovered proteins and to identify interacting partners. In our study of hPTP1E, a cytosolic protein tyrosine phosphatase, we used glutathione S-transferase (GST)-fusion protein of the second PDZ domain to identify interacting peptide motifs by peptide phage display. A consensus motif G X X V W L G was identified and found to be specific for binding to GST-PDZ2 as determined by ELISA, peptide displacement and by protein overlay. However, using nuclear magnetic resonance (NMR), no interaction of the peptide was observed with PDZ2 alone. In co-precipitation experiments using the consensus peptide cross-linked to Affi-Gel, only GST-PDZ2 (but not PDZ2 or GST alone) could be precipitated. These data suggest that there is a potential for identification of artifacts when using fusion proteins in peptide phage display, and one should exercise caution in interpreting these results. It is critical that the interaction be verified using a second, independent system.

Epitope mapping of SHP-1 monoclonal antibodies using peptide phage display.

We have characterized the binding epitopes of four monoclonal antibodies for SHP-1, an SH2 domain containing protein tyrosine phosphatase, using two phage displayed random peptide libraries. Three of the antibodies are directed against the phosphatase domain of the molecule and the fourth is toward the NH2-terminal part of the second SH2 domain. The first two antibodies recognize the sequence NANY, amino acid 305 to amino acid 308, numbered in the non haematopoietic form of human SHP-1 sequence. The third antibody binds the sequence P Y W P (amino acids 365 to 368) located toward the middle of the phosphatase domain of the enzyme. The fourth antibody is directed against the first two amino acids, W Y (amino acids 112 and 113), of the second SH2 domain. The specificities of these antibodies are demonstrated by ELISA and western blot using different protein constructs expressed in bacteria. All the antibodies can detect wild type SHP-1, expressed in 293 cells, by western blot analysis, both under denaturing conditions as well as following renaturation. The data presented here show that the antibodies characterized in this study are raised against linear epitopes and suggest that these epitopes are accessible from the outside in the native SHP-1 molecule.

The origin of differences in the physical properties of the equilibrium forms of cytochrome b5 revealed through high-resolution NMR structures and backbone dynamic analyses.

On the basis of a comparison of high-resolution solution structures calculated for both equilibrium forms of rat ferrocytochrome b5, differences in reduction potential and thermodyanmic stability have been characterized in terms of significant structural and dynamic differences between the two forms. The dominant difference between A and B conformations has long been known to be due to a 180 degrees rotation of the heme in the binding pocket about an axis defined by the alpha- and gamma-meso carbons, however, the B form has not been structurally characterized until now. The most significant differences observed between the two forms were the presence of a hydrogen bond between the 7-propionate and the S64 amide in the A form but not the B form and surprisingly a displacement of the heme out of the binding pocket by 0.9 A in the B form relative to the A form. The magnitude of other factors which could contribute to the known difference in reduction potentials in the bovine protein [Walker, F. A., Emrick, D., Rivera, J. E., Hanquet, B. J., and Buttlaire, D. H. (1988) J. Am. Chem. Soc. 110, 6234-6240], such as differences in the orientation of the axial imidazoles and differences in hydrogen bond strength to the imidazoles, have been evaluated. The dominant effector of the reduction potential would appear to be the lack of the hydrogen bond to the S64 amide in the B form which frees up the propionate to charge stabilize the iron in the oxidized state and thus lower the reduction potential of the B form. The structure we report for the A form, based on heteronuclear NMR restraints, involving a total of 1288 restraints strongly resembles both the X-ray crystal structure of the bovine protein and a recently reported structure for the A form of the rat protein based on homonuclear data alone [Banci, L., Bertini, I., Ferroni, F., and Rosato, A. (1997) Eur. J. Biochem. 249, 270-279]. The rmsd for the backbone atoms of the A form is 0.54 A (0.92 A for all non-hydrogens). The rmsd for the backbone of the B form is 0.51 A (0. 90 A for all non-hydrogen atoms). An analysis of backbone dynamics based on a model-free analysis of 15N relaxation data, which incorporated axially symmetric diffusion tensor modeling of the cytochrome, indicates that the protein is more rigid in the reduced state relative to the oxidized state, based on a comparison with order parameters reported for the bovine protein in the oxidized state [Kelly, G. P., Muskett, F. W., and Whitford, D. (1997) Eur. J. Biochem. 245, 349-354].

SHP-1 associates with both platelet-derived growth factor receptor and the p85 subunit of phosphatidylinositol 3-kinase.

The Src homology 2 (SH2)-containing protein tyrosine phosphatase 1, SHP-1, is highly expressed in all hematopoietic cells as well as in many non-hematopoietic cells, particularly in some malignant epithelial cell lines. In hematopoietic cells, SHP-1 negatively regulates multiple cytokine receptor pathways. The precise function and the targets of SHP-1 in non-hematopoietic cells, however, are largely unknown. Here we demonstrate that SHP-1 associates with both the tyrosine-phosphorylated platelet-derived growth factor (PDGF) receptor and the p85 subunit of phosphatidylinositol 3-kinase in MCF-7 and TRMP cells. Through the use of mutant PDGF receptors and performing peptide competition for immunoprecipitation, it was determined that SHP-1 independently associates with the PDGF receptor and p85 and that its N-terminal SH2 domain is directly responsible for the interactions. Overexpression of SHP-1 in TRMP cells transfected with the PDGF receptor markedly inhibited PDGF-induced c-fos promoter activation, whereas the expression of three catalytically inactive SHP-1 mutants increased the c-fos promoter activation in response to PDGF stimulation. These results indicate that SHP-1 might negatively regulate PDGF receptor-mediated signaling in these cells. Identification of the association of SHP-1 with the PDGF receptor and p85 in MCF-7 and TRMP cells furthers our understanding of the function of SHP-1 in non-hematopoietic cells.

Effect of peptide binding on amide proton exchange rates in the PDZ2 domain from human phosphatase hPTP1E.

Amide hydrogen-deuterium exchange rates were measured in the PDZ2 domain from human phosphatase hPTPIE by 1H-15N heteronuclear NMR spectroscopy. Protection factors were calculated for the slowly exchanging hydrogens in both the free PDZ2 domain and its complex with an octapeptide peptide, R-N-E-I-Q-S-L-V, derived from the C-terminus of the Fas receptor. Aside from a short alpha-helical region alpha1 (amino acids A-45 to D-49), the pattern of highly protected amides correlated well with the presence of hydrogen bonds in elements of the secondary structure. Hydrogen-bonded amides showed relatively fast exchange rates with half-lives of less than 9 h at pD 7.6 and 8 degrees C. Protection factors, calculated as the ratio of theoretical (denatured) and observed exchange rates, showed less dispersion in maximal values than did the actual exchange rates. This behavior and the large pH dependence of the exchange rates suggest that amide exchange is close to the EX2 limit. In this limit, exchange of the most protected amides occurs through a global unfolding mechanism. The free energy of the unfolding calculated from the largest protection factors is 4.8 +/- 0.4 kcal/mol (1 cal = 4.184 J). This deltaG(o) closely matches the value measured by experiments with guanidine hydrochloride and fluorescence emission spectroscopy. Peptide binding to PDZ2 resulted in mostly global effects and stabilized the folded domain by 1.4 kcal/mol.

Optimized gene synthesis, high level expression, isotopic enrichment, and refolding of human interleukin-5.

Structural studies on soluble proteins using nuclear magnetic resonance (NMR) spectroscopy and other structural methods in general require large quantities of isotopically enriched proteins. Human interleukin-5 is a disulfide-linked homodimeric cytokine implicated in asthmatic response. The development of a high yield overexpression system for human interleukin-5 is an important prerequisite to using modern multidimensional NMR in the characterization of the solution structure of the protein and to characterize interactions with a soluble receptor domain. Significant amounts of the protein were expressed using an optimized synthetic gene in a high yield expression system. Gene synthesis was accomplished through the ligation of six oligonucleotides composed of optimized codons. The ligated fragments were further amplified by a polymerase chain reaction and then subcloned into the T7 RNA polymerase based overexpression vector pET11a. However, the induced protein accumulated in the form of inclusion bodies. Initially, the protein was solubilized under denaturing conditions and purified in these denaturing conditions by passage through a single S-200 HR sizing column. Finally, protein refolding was initiated in the presence of 2 M urea followed by dialysis. This protocol yielded 40 mg of biologically active, isotope-enriched protein from 4 liters of minimal medium thus facilitating structural studies by NMR. The strategy described may be of immense value in the production of significant quantities of recombinant, eukaryotic proteins for structural and other studies.

Characterization of a site-directed mutant of cytochrome b5 designed to alter axial imidazole ligand plane orientation.

Mutants of cytochrome b5 were designed to achieve reorientation of individual axial imidazole ligands. The orientation of the axial ligand planes is thought to modulate the reduction potential of bis(imidazole) axially ligated heme proteins. The A67V mutation achieved this goal through the substitution of a bulkier, hydrophobic ligand for a residue, in the sterically hindered hydrophobic heme binding pocket. Solution structures of mutant and wild-type proteins in the region of the mutation were calculated using restraints obtained from 1H and 15N 2D homonuclear and heteronuclear NMR spectra and 1H-15N 3D heteronuclear NMR spectra. More than 10 restraints per residue were used in the refinement of both structures. Average local rmsd for 20 refined structures was 0.30 A for the wild-type structure and 0.38 A for the A67V mutant. The transfer of amide proton resonance assignments from wild-type to the mutant protein was achieved through overlays of 15N-1H heteronuclear correlation spectra of the reduced proteins. Side chain assignments and sequential assignments were established using conventional assignment strategies. Calculation of the orientation of the components of the anisotropic paramagnetic susceptibility tensor, using methods similar to procedures applied to the wild-type protein, shows that the orientation of the in-plane components are identical in the wild-type and mutant proteins. However, the orientation of the z-component of the susceptibility tensor calculated for the mutant protein differs by 17 degrees for the A-form and by 11 degrees for the B-form from the orientation calculated for the wild-type protein. The rotation of the z-component of the susceptibility tensor (toward the delta meso proton) is in the same direction and is of the same magnitude as the rotation of the H63 imidazole ring induced by mutation.

Protein-tyrosine phosphatase SHP2 is positively linked to proteinase-activated receptor 2-mediated mitogenic pathway.

Proteinase-activated receptor-2 (PAR2), a new member of family of the G protein-coupled receptors, is activated by proteolytic cleavage of its extracellular amino terminus, a mechanism similar to that used by the thrombin receptor. It has been suggested that PAR2 has a potential role in the late phases of the acute inflammatory response and in tissue repair and/or skin-related disorders. Here we demonstrate that the agonist peptide (SLIGRL) stimulated c-fos-mediated mitogenic activation and tyrosine phosphorylation of cellular proteins. One of the tyrosine-phosphorylated proteins was identified as an Src homology-2 domain-containing protein-tyrosine phosphatase, SHP2. The stimulatory effect of the agonist peptide on early gene transcription was markedly blocked by pertussis toxin treatment whereas the induced tyrosine phosphorylation of SHP2 was completely abolished by the drug. More importantly, while expression of wild-type SHP2 enhanced the agonist-stimulatory mitogenic activity, overexpression of a catalytically inactive mutant of SHP2 strongly suppressed the stimulatory effect of the agonist peptide on both early gene transcription and DNA synthesis. These results suggest that SHP2 acts as a positive regulator linked to the PAR2-mediated mitogenic pathway coupled to a pertussis toxin-sensitive heterotrimeric G protein. Demonstration of SHP2 as a positive mediator in a G protein-coupled, receptor-mediated signaling adds to our understanding of the function of both SHP2 and PAR2 in the signaling pathway.

1H, 13C and 15N NMR assignments and secondary structure of the paramagnetic form of rat cytochrome b5.

Modern multidimensional double- and triple-resonance NMR methods have been applied to assign the backbone and side-chain 13C resonances for both equilibrium conformers of the paramagnetic form of rat liver microsomal cytochrome b5. The assignment of backbone 13C resonances was used to confirm previous 1H and 15N resonance assignments [Guiles, R.D. et al. (1993) Biochemistry, 32, 8329-8340]. On the basis of short- and medium-range NOEs and backbone 13C chemical shifts, the solution secondary structure of rat cytochrome b5 has been determined. The striking similarity of backbone 13C resonances for both equilibrium forms strongly suggests that the secondary structures of the two isomers are virtually identical. It has been found that the 13C chemical shifts of both backbone and side-chain atoms are relatively insensitive to paramagnetic effects. The reliability of such methods in anisotropic paramagnetic systems, where large pseudocontact shifts can be observed, is evaluated through calculations of the magnitude of such shifts.

Differential promoter usage in prolactin receptor gene expression: hepatocyte nuclear factor 4 binds to and activates the promoter preferentially active in the liver.

Characterization of the rat PRL receptor (PRLR) gene has revealed three separate untranslated exon 1 sequences, each associated with a different transcription start site and 5'-flanking sequence. We show by RT-PCR that exon 1A is expressed primarily in liver but is also detectable in ovary and mammary gland. Exon 1B expression is observed exclusively in the ovary, whereas exon 1C is expressed in all three tissues. Transient transfection of luciferase reporter constructs containing parts of the 5'-flanking regions (0.3-1.1 kb) of exon 1A, 1B, and 1C, respectively, showed activity of the 1A promoter in Chinese hamster ovary (CHO) cells, the human hepatoma cell line, HepG2, and the rat hepatoma cell line, H4II, which was 10- to 14-fold increased compared with the activity of the promoter-less luciferase vector. No activity of the 1A promoter was detected in the human mammary cell line, T-47D. Relative to a vector containing the Simian virus 40 (SV40) promoter, the 1A promoter had 20% activity in H4II cells and 1-3% activity in CHO and HepG2 cells. The 1B promoter produced a 6.1-fold increase of luciferase activity in CHO cells (approximately 2% of the SV40 promoter), whereas no significant activity was detected in HepG2, H4II, and T-47D cells. The 1C promoter was strongly active in T-47D cells (approximately 64-fold over control) and moderately active in the other cell lines tested (9- to 13-fold over control). 5'-Deletion analysis of the 1A promoter revealed that a fragment containing -83/ +81 bp, relative to the transcription start site, was sufficient to drive transcription in hepatoma cells, whereas this construct was inactive in CHO cells. Cotransfection of CHO cells with the -83/+81 construct and an expression vector encoding the liver-enriched transcription factor, hepatocyte nuclear factor 4 (HNF4), revealed a dose-dependent transactivation of the proximal 1A promoter with a maximal stimulation of approximately 10-fold. Electrophoretic mobility shift assays showed binding of HNF4 to the sequence -14/+24 of the 1A promoter, and mutational analysis revealed that the sequence GGGCAAAGTCA at position +11/+21 is required for this binding. We conclude that the 1A, 1B, and 1C promoters of the PRLR gene are used in a cell type- dependent way that may play a role in differential hormonal regulation of the gene. In particular, we have shown that HNF4 operates on the proximal 1A promoter and may be responsible, in combination with other factors, for the increased activity of this promoter in adult female liver.

Positive effect of overexpressed protein-tyrosine phosphatase PTP1C on mitogen-activated signaling in 293 cells.

PTP1C, an SH2 domain-containing protein-tyrosine phosphatase, is predominantly expressed in hematopoietic cells, in which it negatively regulates cellular signaling. However, this enzyme is also expressed in many non-hematopoietic cells. We demonstrate here that in non-hematopoietic 293 cells, overexpression of a catalytically inactive mutant of PTP1C strongly suppressed the stimulatory effects of the epidermal growth factor or serum on cell proliferation, early gene transcription, and DNA synthesis. Similarly, the phosphorylation of the mitogen-activated protein kinase and mitogen-activated protein kinase kinase activity was markedly inhibited by overexpression of mutant PTP1C. The inhibitory effect of mutant PTP1C was overcome by cotransfection with wild-type PTP1C, but not with the structurally related PTP2C. Furthermore, expression of the mutant phosphatase resulted in hyperphosphorylation on tyrosine of a 95-kDa protein that was co-immunoprecipitated with the mutant, but not with the wild-type protein. These results suggest that, unlike in hematopoietic cells, PTP1C in 293 cells plays a positive role in epidermal growth factor- or serum-activated mitogenesis. Thus, PTP1C participates in multiple signaling pathways, where the enzyme, depending on its target molecules, may function as either a positive or negative mediator.