Differential expression pattern of pituitary adenylate cyclase-activating polypeptide (PACAP) alternative splicing variants and its receptors in the immune system of rainbow trout (Oncorhynchus mykiss)
“…We were unable to detect vpac2 in this cell line (data not shown). This is consistent with previous results showing an absence of vpac2 expression in rainbow trout cultured macrophages and peripheral blood mononuclear cells [25] Fig. 3 Effect of phosphodiesterase inhibitor IBMX on LPS-induced il-1β (A), tnf-α (B), il-10 (C), vpac1 (D) and pac1 (E) expression in SHK-1 cells.…”
“…We were unable to detect vpac2 in this cell line (data not shown). This is consistent with previous results showing an absence of vpac2 expression in rainbow trout cultured macrophages and peripheral blood mononuclear cells [25] Fig. 3 Effect of phosphodiesterase inhibitor IBMX on LPS-induced il-1β (A), tnf-α (B), il-10 (C), vpac1 (D) and pac1 (E) expression in SHK-1 cells.…”
“…In the absence of bacterial infection, PACAP was shown to stimulate pro-inflammatory cytokine expression 48 h following PACAP treatment as well increasing the expression of one of the PACAP receptors, VPAC1 . When analyzing PACAP receptor expression in RTS11, it is important to note that only VPAC1 and PAC1 receptor genes were measured as it has previously been shown by Lugo et al (55) that these cells do not express the third receptor gene, VPAC2 . Lugo et al (55) also showed that despite PAC1 presenting the highest constitutive expression in all rainbow trout lymphoid tissues in vivo , this was not observed in RTS11 where VPAC1 presents the greatest expression.…”
Section: Discussionmentioning
confidence: 99%
“…When analyzing PACAP receptor expression in RTS11, it is important to note that only VPAC1 and PAC1 receptor genes were measured as it has previously been shown by Lugo et al (55) that these cells do not express the third receptor gene, VPAC2 . Lugo et al (55) also showed that despite PAC1 presenting the highest constitutive expression in all rainbow trout lymphoid tissues in vivo , this was not observed in RTS11 where VPAC1 presents the greatest expression. As PAC1 has been found to be a fundamental type I receptor for PACAP this result was unexpected.…”
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a multifunctional neuropeptide that is widely distributed in mammals and is capable of performing roles as a neurotransmitter, neuromodulator, and vasodilator. This polypeptide belongs to the glucagon/secretin superfamily, of which some members have been shown to act as antimicrobial peptides in both mammalian and aquatic organisms. In teleosts, PACAP has been demonstrated to have direct antimicrobial activity against several aquatic pathogens, yet this phenomenon has never been studied throughout a live bacterial challenge. The present study focuses on the influence of synthetic
Clarias gariepinus
38 amino acid PACAP on the rainbow trout monocyte/macrophage-like cell line, RTS11, when exposed to the coldwater bacterial pathogen
Flavobacterium psychrophilum
. PACAP was shown to have direct antimicrobial activity on
F. psychrophilum
when grown in both cytophaga broth and cell culture media (L-15). Further, the ability of teleostean PACAP to permeabilize the membrane of an aquatic pathogen,
F. psychrophilum
, was demonstrated for the first time. The viability of RTS11 when exposed to PACAP was also observed using a trypan blue exclusion assay to determine optimal experimental doses of the antimicrobial peptide. This displayed that only concentrations higher than 0.1 μM negatively impacted RTS11 survival. Interestingly, when RTS11 was pre-treated with PACAP for 24 h before experiencing infection with live
F. psychrophilum
, growth of the pathogen was severely inhibited in a dose-dependent manner when compared to cells receiving no pre-treatment with the polypeptide. Relative expression of pro-inflammatory cytokines (IL-1β, TNFα, and IL-6) and PACAP receptors (VPAC1 and PAC1) was also analyzed in RTS11 following PACAP exposure alone and in conjunction with live
F. psychrophilum
challenge. These qRT-PCR findings revealed that PACAP may have a synergistic effect on RTS11 immune function. The results of this study provide evidence that PACAP has immunostimulatory activity on rainbow trout immune cells as well as antimicrobial activity against aquatic bacterial pathogens such as
F. psychrophilum
. As there are numerous pathogens that plague the aquaculture industry, PACAP may stimulate the teleost immune system while also providing an efficacious alternative to antibiotic use.
“…The distribution of PAC1 has been examined in many species using different techniques that revealed widespread expression in different tissues, including the nervous, cardiovascular, endocrine, immune, and respiratory systems (Aino et al, 1995; Abu-Hamdan et al, 2006; Gomariz et al, 2006; Molnar et al, 2008; Jolivel et al, 2009; Shneider et al, 2010; Lugo et al, 2011; Buljan et al, 2012). However, knowledge concerning the expression of PAC1 splice variants is somewhat limited at it is mainly based on analyses of isolated brain areas and/or primary cell cultures.…”
Section: Expression Of Pac1 Splice Isoforms In the Nervous Systemmentioning
Alternative splicing of the precursor mRNA encoding for the neuropeptide receptor PAC1/ADCYAP1R1 generates multiple protein products that exhibit pleiotropic activities. Recent studies in mammals and zebrafish have implicated some of these splice isoforms in control of both cellular and body homeostasis. Here, we review the regulation of PAC1 splice variants and their underlying signal transduction and physiological processes in the nervous system.
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