PAC1R agonist maxadilan enhances hADSC viability and neural differentiation potential

PAC1 Agonist Maxadilan Reduces Atherosclerotic Lesions in Hypercholesterolemic ApoE-Deficient Mice

A possible involvement of immune- and vasoregulatory PACAP signaling at the PAC1 receptor in atherogenesis and plaque-associated vascular inflammation has been suggested. Therefore, we tested the PAC1 receptor agonist Maxadilan and the PAC1 selective antagonist M65 on plaque development and lumen stenosis in the ApoE-/- atherosclerosis model for possible effects on atherogenesis. Adult male ApoE-/- mice were fed a cholesterol-enriched diet (CED) or standard chow (SC) treated with Maxadilan, M65 or Sham. Effects of treatment on atherosclerotic plaques, lumen stenosis, apoptosis and pro-inflammatory signatures were analyzed in the brachiocephalic trunk (BT). The percentage of Maxadilan treated mice exhibiting plaques under SC and CED was lower than that of Sham or M65 treatment indicating opposite effects of Maxadilan and M65. Maxadilan application inhibited lumen stenosis in SC and CED mice compared to the Sham mice. In spite of increased cholesterol levels, lumen stenosis of Maxadilan-treated mice was similar under CED and SC. In contrast, M65 under SC or CED did not reveal a significant influence on lumen stenosis. Maxadilan significantly reduced the TNF-α-immunoreactive (TNF-α+) area in the plaques under CED, but not under SC. In contrast, the IL-1β+ area was reduced after Maxadilan treatment in SC mice but remained unchanged in CED mice compared to Sham mice. Maxadilan reduced caspase-3 immunoreactive (caspase-3+) in the tunica media under both, SC and CED without affecting lipid content in plaques. Despite persistent hypercholesterolemia, Maxadilan reduces lumen stenosis, apoptosis and TNF-α driven inflammation. Our data suggest that Maxadilan provides atheroprotection by acting downstream of hypercholesterolemia-induced vascular inflammation. This implicates the potential of PAC1-specific agonist drugs against atherosclerosis even beyond statins and PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitors.

Downregulation of PACAP and the PAC1 Receptor in the Basal Ganglia, Substantia Nigra and Centrally Projecting Edinger-Westphal Nucleus in the Rotenone model of Parkinson's Disease

Numerous in vitro and in vivo models of Parkinson's disease (PD) demonstrate that pituitary adenylate cyclase-activating polypeptide (PACAP) conveys its strong neuroprotective actions mainly via its specific PAC1 receptor (PAC1R) in models of PD. We recently described the decrease in PAC1R protein content in the basal ganglia of macaques in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD that was partially reversed by levodopa therapy. In this work, we tested whether these observations occur also in the rotenone model of PD in the rat. The rotarod test revealed motor skill deterioration upon rotenone administration, which was reversed by benserazide/levodopa (B/L) treatment. The sucrose preference test suggested increased depression level while the open field test showed increased anxiety in rats rendered parkinsonian, regardless of the received B/L therapy. Reduced dopaminergic cell count in the substantia nigra pars compacta (SNpc) diminished the dopaminergic fiber density in the caudate-putamen (CPu) and decreased the peptidergic cell count in the centrally projecting Edinger-Westphal nucleus (EWcp), supporting the efficacy of rotenone treatment. RNAscope in situ hybridization revealed decreased PACAP mRNA (Adcyap1) and PAC1R mRNA (Adcyap1r1) expression in the CPu, globus pallidus, dopaminergic SNpc and peptidergic EWcp of rotenone-treated rats, but no remarkable downregulation occurred in the insular cortex. In the entopeduncular nucleus, only the Adcyap1r1 mRNA was downregulated in parkinsonian animals. B/L therapy attenuated the downregulation of Adcyap1 in the CPu only. Our current results further support the evolutionarily conserved role of the PACAP/PAC1R system in neuroprotection and its recruitment in the development/progression of neurodegenerative states such as PD.

Pituitary Adenylate Cyclase-activating Polypeptide (PACAP) -derived Peptide MPAPO Stimulates Adipogenic Differentiation by Regulating the Early Stage of Adipogenesis and ERK Signaling Pathway

Regenerative medicine and tissue engineering have delivered new healing possibilities to the treatment of soft tissue defects, but the selection of seed cells is critical for treatment. Adipose-derived stem cells have perpetually been a preferred candidate for seed cells due to their wealthy sources, simple access, high plasticity, and powerful value-added capabilities. How to improve the efficiency of adipogenic differentiation is the key to the treatment. Pituitary adenylate cyclase-activating peptide, as a biologically active peptide secreted by the pituitary, is widely involved in regulating the body's sugar metabolism and lipid metabolism. However, the effects of MPAPO in ADSCs adipogenic differentiation remain unknown. Our results reveal that MPAPO treatment improves the adipogenic differentiation efficiency of ADSCs, including promoting the accumulation of lipid droplets and triglycerides, and the expression of adipocyte protein biomarkers PPARγ and C/EBPa. Additionally, the mechanism studies showed that the effective window of MPAPO-induced adipogenesis was the first 3 days during ADSCs differentiation. MPAPO selectively binds to the PAC1 receptor and promotes adipogenic differentiation of ADSCs by activating the ERK signaling pathway and elevating cell proliferation during postconfluent mitosis stage. Altogether, we demonstrate that MPAPO plays a crucial role in ADSCs adipogenesis, providing experimental basis and data for exploring therapeutic options in tissue defect repair.

GIP receptor suppresses PAC1receptor-mediated neuronal differentiation via formation of a receptor heterocomplex

Pituitary adenylate cyclase-activating peptide (PACAP) receptor (PAC1R) is a class B Gprotein-coupled receptor (GPCR) that is widely expressed in the human body and is involved in neuronal differentiation. As class B GPCRs are known to form heterocomplexes with family members, we hypothesized that PAC1R mediates neuronal differentiation through interaction with a class B GPCR. We used the BRET assay to identify potential interactions between PAC1R and 11 class B GPCRs. Gastric inhibitory polypeptide receptor (GIPR) and secretin receptor were identified as putative binding partners of PAC1R. The effect of heterocomplex formation by PAC1R on receptor activation was evaluated with the cyclic (c)AMP, luciferase reporter, and calcium signaling assays; and the effects on receptor internalization and subcellular localization were examined by confocal microscopy. The results suggested he PAC1R/GIPR heterocomplex suppressed signaling events downstream of PAC1R, including cAMP production, serum response element and calcium signaling, and β-arrestin recruitment. Protein-protein interaction was analyzed in silico, and induction of neuronal differentiation by the PAC1R heterocomplex was assessed in SH-SY5Y neuronal cells by measure the morphological changes and marker genes expression by real-time quantitative PCR and western blot. Over-expression of GIPR suppressed PACAP/PAC1R-mediated neuronal differentiation and the differentiation markers expression in SH-SY5Y cells. GIPR regulates neuronal differentiation through heterocomplex formation with PAC1R.

Lack of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) Disturbs Callus Formation

Pituitary adenylate cyclase–activating polypeptide (PACAP) is a naturally secreted signaling peptide and has important regulatory roles in the differentiation of the central nervous system and its absence results in disorders in femur development. PACAP has an important function in prevention of oxidative stress or mechanical stress in chondrogenesis but little is known about its function in bone regeneration. A new callus formation model was set to investigate its role in bone remodeling. Fracturing was 5 mm distal from the proximal articular surface of the tibia and the depth was 0.5 mm. Reproducibility of callus formation was investigated with CT 3, 7, and 21 days after the operation. Absence of PACAP did not alter the alkaline phosphatase (ALP) activation in PACAP KO healing process. In developing callus, the expression of collagen type I increased in wild-type (WT) and PACAP KO mice decreased to the end of healing process. Expression of the elements of BMP signaling was disturbed in the callus formation of PACAP KO mice, as bone morphogenic protein 4 (BMP4) and 6 showed an early reduction in bone regeneration. However, elevated Smad1 expression was demonstrated in PACAP KO mice. Our results indicate that PACAP KO mice show various signs of disturbed bone healing and suggest PACAP compensatory and fine tuning effects in proper bone regeneration.

Differentiation of human adipose derived stem cells into Leydig-like cells with molecular compounds

Leydig cells (LCs) are the primary source of testosterone in the testis, and testosterone deficiency caused by LC functional degeneration can lead to male reproductive dysfunction. LC replacement transplantation is a very promising approach for this disease therapy. Here, we report that human adipose derived stem cells (ADSCs) can be differentiated into Leydig-like cells using a novel differentiation method based on molecular compounds. The isolated human ADSCs expressed positive CD29, CD44, CD59 and CD105, negative CD34, CD45 and HLA-DR using flow cytometry, and had the capacity of adipogenic and osteogenic differentiation. ADSCs derived Leydig-like cells (ADSC-LCs) acquired testosterone synthesis capabilities, and positively expressed LC lineage-specific markers LHCGR, STAR, SCARB1, SF-1, CYP11A1, CYP17A1, HSD3B1 and HSD17B3 as well as negatively expressed ADSC specific markers CD29, CD44, CD59 and CD105. When ADSC-LCs labelled with lipophilic red dye (PKH26) were injected into rat testes which were selectively eliminated endogenous LCs using ethylene dimethanesulfonate (EDS, 75 mg/kg), the transplanted ADSC-LCs could survive and function in the interstitium of testes, and accelerate the recovery of blood testosterone levels and testis weights. These results demonstrated that ADSCs could be differentiated into Leydig-like cells by few defined molecular compounds, which might lay the foundation for further clinical application of ADSC-LC transplantation therapy.

Differentiation of human induced pluripotent stem cells into Leydig-like cells with molecular compounds

Leydig cells (LCs) play crucial roles in producing testosterone, which is critical in the regulation of male reproduction and development. Low levels of testosterone will lead to male hypogonadism. LC transplantation is a promising alternative therapy for male hypogonadism. However, the source of LCs limits this strategy for clinical applications. Thus far, others have reported that LCs can be derived from stem cells by gene transfection, but the safe and effective induction method has not yet been reported. Here, we report that Leydig-like cells can be derived from human induced pluripotent stem cells (iPSCs) using a novel differentiation protocol based on molecular compounds. The iPSCs-derived Leydig-like cells (iPSC-LCs) acquired testosterone synthesis capabilities, had the similar gene expression profiles with LCs, and positively expressed Leydig cell lineage-specific protein markers LHCGR, STAR, SCARB1, SF-1, CYP11A1, HSD3B1, and HSD17B3 as well as negatively expressed iPSC-specific markers NANOG, OCT4, and SOX2. When iPSC-LCs labeled with lipophilic red dye (PKH26) were transplanted into rat testes that were selectively eliminated endogenous LCs using EDS (75 mg/kg), the transplanted iPSC-LCs could survive and function in the interstitium of testes, and accelerate the recovery of serum testosterone levels and testis weights. Collectively, these findings demonstrated that the iPSCs were able to be differentiated into Leydig-like cells by few defined molecular compounds, which may lay the safer groundwork for further clinical application of iPSC-LCs for hypogonadism.

Conditioned Media From Glial Cells Promote a Neural-Like Connexin Expression in Human Adipose-Derived Mesenchymal Stem Cells

The expression of neuronal and glial connexins (Cxs) has been evaluated in adipose-derived mesenchymal stem cells (ASCs) whose neural differentiation was promoted by a conditioned medium (CM) obtained from cultures of olfactory ensheathing cells (OECs) or Schwann cells (SCs). By immunocytochemistry and flow cytometer analysis it was found that Cx43 was already considerably expressed in naïve ASCs and further increased after 24 h and 7 days from CM exposition. Cx32 and Cx36 were significantly improved in conditioned cultures compared to control ASCs, whereas a decreased expression was noticed in the absence of CM treatments. Cx47 was virtually absent in any conditions. Altogether, high basal levels and induced increases of Cx43 expression suggest a potential attitude of ASCs toward an astrocyte differentiation, whereas the lack of Cx47 would indicate a poor propensity of ASCs to become oligodendrocytes. CM-evoked Cx32 and Cx36 increases showed that a neuronal- or a SC-like differentiation can be promoted by using this strategy. Results further confirm that environmental cues can favor an ASC neural differentiation, either as neuronal or glial elements. Of note, the use of glial products present in CM rather than the addition of chemical agents to achieve such differentiation would resemble "more physiological" conditions of differentiation. As a conclusion, the overexpression of typical neural Cxs would indicate the potential capability of neural-like ASCs to interact with neighboring neural cells and microenvironment.

Cocktail of Chemical Compounds and Recombinant Proteins Robustly Promote the Stemness of Adipose-Derived Stem Cells

Induced pluripotent stem cells (iPSCs) from somatic cells can be reprogrammed to provide an unlimited cell resource showing great potential in disease modeling and regenerative medicine. However, the traditional method for reprogramming cells into iPSCs using genome-integrating retro- or lenti-viruses remain an obstacle for its application in clinical settings. We tried the possibility to generate pre-iPSCs from human adipose-derived stem cells (ADSCs) by nongenetic reprogramming using recombinant cell-penetrating proteins OCT4/KLF4/SOX2 (PTD-OKS) and the cocktail of small molecules (VCFZ). Our experimental results demonstrated that PTD-OKS in combination with VCFZ (VCFZ+OKS) could significantly enhance the stemness of ADSCs and easily get pre-iPSCs after 25 days treatments. The pre-iPSCs showed similar morphology to iPSCs, which were positive for alkaline phosphatase staining. Furthermore, RT-polymerase chain reaction analysis showed that VCFZ+OKS could significantly upregulate the expression of OCT4, KLF4, SOX2, and NANOG gene after 25 days treatment. And immunofluorescence staining also showed that the protein makers of pluripotent stem cell were positively expressed in VCFZ+OKS treated group. Our data suggest that nongenetic-mediated reprogramming from ADSCs may be a promising stem cell sources for cell therapy in the near future.

Induced pluripotent stem cell-derived conditional medium promotes Leydig cell anti-apoptosis and proliferation via autophagy and Wnt/β-catenin pathway

Leydig cell transplantation is a better alternative in the treatment of androgen-deficient males. The main purpose of this study was to investigate the effects of induced pluripotent stem cell-derived conditioned medium (iPS-CM) on the anti-apoptosis, proliferation and function of immature Leydig cells (ILCs), and illuminate the underlying mechanisms. ILCs were exposed to 200 μmol/L hydrogen peroxide (H2 O2 ) for 24 hours with or without iPS-CM treatments. Cell apoptosis was detected by flow cytometric analysis. Cell proliferation was assessed using cell cycle assays and EdU staining. The steroidogenic enzyme expressions were quantified with Western blotting. The results showed that iPS-CM significantly reduced H2 O2 -induced ILC apoptosis through down-regulation of autophagic and apoptotic proteins LC3-I/II, Beclin-1, P62, P53 and BAX as well as up-regulation of BCL-2, which could be inhibited by LY294002 (25 μmol/L). iPS-CM could also promote ILC proliferation through up-regulation of β-catenin and its target proteins cyclin D1, c-Myc and survivin, but was inhibited by XAV939 (10 μmol/L). The level of bFGF in iPS-CM was higher than that of DMEM-LG. Exogenous bFGF (20 ng/mL) or Wnt signalling agonist lithium chloride (LiCl) (20 mmol/L) added into DMEM-LG could achieve the similar effects of iPS-CM. Meanwhile, iPS-CM could improve the medium testosterone levels and up-regulation of LHCGR, SCARB1, STAR, CYP11A1, HSD3B1, CYP17A1, HSD17B3 and SF-1 in H2 O2 -induced ILCs. In conclusion, iPS-CM could reduce H2 O2 -induced ILC apoptosis through the activation of autophagy, promote proliferation through up-regulation of Wnt/β-catenin pathway and enhance testosterone production through increasing steroidogenic enzyme expressions, which might be used in regenerative medicine for future.

Genome-Wide Analysis Identified a Number of Dysregulated Long Noncoding RNA (lncRNA) in Human Pancreatic Ductal Adenocarcinoma

BACKGROUND

Long noncoding RNAs have been shown to play crucial roles in cancer biology, while the long noncoding RNA landscapes of pancreatic ductal adenocarcinoma have not been completely characterized. We aimed to determine whether long noncoding RNA could serve as early diagnostic biomarkers for pancreatic ductal adenocarcinoma.

METHOD

We conducted a genome-wide microarray analysis on pancreatic ductal adenocarcinoma and their adjacent noncancerous tissues from 8 Chinese patients.

RESULTS

A total of 3352 significantly differentially expressed long noncoding RNAs were detected. Of total, 1249 long noncoding RNAs were upregulated and 2103 were downregulated (fold change ≥2, P < 0.05, FDR <0.05). These differentially expressed long noncoding RNAs were not evenly distributed among chromosomes in human genome. Hierarchical clustering of these differentially expressed long noncoding RNAs revealed large variabilities in long noncoding RNA expression among individual patient, indicating that certain long noncoding RNAs could play a unique role or be used as a biomarker for specific subtype of pancreatic ductal adenocarcinoma. Gene Ontology enrichment and pathway analysis identified several remarkably dysregulated pathways in pancreatic ductal adenocarcinoma tissue, such as interferon-γ-mediated signaling pathway, mitotic cell cycle and proliferation, extracellular matrix receptor interaction, focal adhesion, and regulation of actin cytoskeleton. The co-expression network analysis detected 393 potential interactions between 80 differentially expressed long noncoding RNAs and 105 messenger RNAs. We experimentally verified 7 most markedly dysregulated long noncoding RNAs from the network.

CONCLUSION

Our study provided a genome-wide survey of dysregulated long noncoding RNAs and long noncoding RNA/messenger RNA co-regulation networks in pancreatic ductal adenocarcinoma tissue. These dysregulated long noncoding RNA/messenger RNA networks could be used as biomarkers to provide early diagnosis of pancreatic ductal adenocarcinoma or its subtype, predict prognosis, and evaluate treatment efficacy.

Alteration of the PAC1 Receptor Expression in the Basal Ganglia of MPTP-Induced Parkinsonian Macaque Monkeys

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a well-known neuropeptide with strong neurotrophic and neuroprotective effects. PACAP exerts its protective actions via three G protein-coupled receptors: the specific Pac1 receptor (Pac1R) and the Vpac1/Vpac2 receptors, the neuroprotective effects being mainly mediated by the Pac1R. The protective role of PACAP in models of Parkinson's disease and other neurodegenerative diseases is now well-established in both in vitro and in vivo studies. PACAP and its receptors occur in the mammalian brain, including regions associated with Parkinson's disease. PACAP receptor upregulation or downregulation has been reported in several injury models or human diseases, but no data are available on alterations of receptor expression in Parkinson's disease. The model closest to the human disease is the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced macaque model. Therefore, our present aim was to evaluate changes in Pac1R expression in basal ganglia related to Parkinson's disease in a macaque model. Monkeys were rendered parkinsonian with MPTP, and striatum, pallidum, and cortex were evaluated for Pac1R immunostaining. We found that Pac1R immunosignal was markedly reduced in the caudate nucleus, putamen, and internal and external parts of the globus pallidus, while the immunoreactivity remained unchanged in the cortex of MPTP-treated parkinsonian monkey brains. This decrease was attenuated in some brain areas in monkeys treated with L-DOPA. The strong, specific decrease of the PACAP receptor immunosignal in the basal ganglia of parkinsonian macaque monkey brains suggests that the PACAP/Pac1R system may play an important role in the development/progression of the disease.

The Protective Role of PAC1-Receptor Agonist Maxadilan in BCCAO-Induced Retinal Degeneration

A number of studies have proven that pituitary adenylate cyclase activating polypeptide (PACAP) is protective in neurodegenerative diseases. Permanent bilateral common carotid artery occlusion (BCCAO) causes severe degeneration in the rat retina. In our previous studies, protective effects were observed with PACAP1-38, PACAP1-27, and VIP but not with their related peptides, glucagon, or secretin in BCCAO. All three PACAP receptors (PAC1, VPAC1, VPAC2) appear in the retina. Molecular and immunohistochemical analysis demonstrated that the retinoprotective effects are most probably mainly mediated by the PAC1 receptor. The aim of the present study was to investigate the retinoprotective effects of a selective PAC1-receptor agonist maxadilan in BCCAO-induced retinopathy. Wistar rats were used in the experiment. After performing BCCAO, the right eye was treated with intravitreal maxadilan (0.1 or 1 μM), while the left eye was injected with vehicle. Sham-operated rats received the same treatment. Two weeks after the operation, retinas were processed for standard morphometric and molecular analysis. Intravitreal injection of 0.1 or 1 μM maxadilan caused significant protection in the thickness of most retinal layers and the number of cells in the GCL compared to the BCCAO-operated eyes. In addition, 1 μM maxadilan application was more effective than 0.1 μM maxadilan treatment in the ONL, INL, IPL, and the entire retina (OLM-ILM). Maxadilan treatment significantly decreased cytokine expression (CINC-1, IL-1α, and L-selectin) in ischemia. In summary, our histological and molecular analysis showed that maxadilan, a selective PAC1 receptor agonist, has a protective role in BCCAO-induced retinal degeneration, further supporting the role of PAC1 receptor conveying the retinoprotective effects of PACAP.