Transcriptional regulation of the human cholecystokinin gene: composite action of upstream stimulatory factor, Sp1, and members of the CREB/ATF-AP-1 family of transcription factors

Evidence that increased cholecystokinin (CCK) in the periaqueductal gray (PAG) facilitates changes in Resident-Intruder social interactions triggered by peripheral nerve injury

Individual differences in the effects of a chronic neuropathic injury on social behaviours characterize both the human experience and pre-clinical animal models. The impacts of these changes to the well-being of the individual are often underappreciated. Earlier work from our laboratory using GeneChip® microarrays identified increased cholecystokinin (CCK) gene expression in the periaqueductal gray (PAG) of rats that showed persistent changes in social interactions during a Resident-Intruder encounter following sciatic nerve chronic constriction injury (CCI). In this study, we confirmed these gene regulation patterns using RT-PCR and identified the anatomical location of the CCK-mRNA as well as the translated CCK peptides in the midbrains of rats with a CCI. We found that rats with persistent CCI-induced changes in social behaviours had increased CCK-mRNA in neurons of the ventrolateral PAG and dorsal raphe nuclei, as well as increased CCK-8 peptide expression in terminal boutons located in the lateral and ventrolateral PAG. The functional significance of these changes was explored by microinjecting small volumes of CCK-8 into the PAG of uninjured rats and observing their Resident-Intruder social interactions. Disturbances to social interactions identical to those observed in CCI rats were evoked when injection sites were located in the rostral lateral and ventrolateral PAG. We suggest that CCI-induced changes in CCK expression in these PAG regions contributes to the disruptions to social behaviours experienced by a subset of individuals with neuropathic injury.

SNP-SNP interactions in the BDNF, COMT, CBR1 and CCK genes, associated with post-traumatic stress disorder in urban residents of Itagüí, Colombia

Introducción. Los polimorfismos de un solo nucleótido (SNP, por su sigla en inglés) en los genes BDNF, COMT, CBR1 y CCK han sido asociados con el proceso de extinción del miedo en humanos. Dado que la extinción del miedo es clave para la recuperación del trauma psicológico, es posible que estos genes modulen el riesgo de desarrollar trastorno de estrés postraumático (TEPT).Objetivo. Evaluar las asociaciones unilocus y multilocus entre los SNP en los genes BDNF, COMT, CBR1 y CCK y el riesgo de desarrollar TEPT.Materiales y métodos. 129 habitantes del municipio de Itagüí, Colombia, que habían experimentado trauma psicológico al menos una vez, fueron genotipificados para estos polimorfismos (38 casos de TEPT y 91 controles). Se realizaron pruebas de asociación unilocus y multilocus por regresión logística para SNP únicos y las combinaciones genotípicas SNP-SNP existentes.Resultados. No se encontraron asociaciones unilocus, pero se observaron interacciones entre BDNF y CBR1, y CCK y COMT. De estas interacciones, las combinaciones genotípicas que se comportaron como factores de riesgo fueron AG-AA (OR=13.52, p<0.05) de BDNF-CBR1 y TC-AA (OR=13.70, p<0.05) de CCK-COMT.Conclusiones: Los dos pares de polimorfismos en interacción encontrados en el presente estudio podrían actuar de forma aditiva y generar un mayor riesgo de desarrollar TEPT después de sufrir trauma psicológico. Quienes portan un solo alelo tienen un menor riesgo de desarrollar el trastorno que quienes portan dos alelos en genes que interactúan entre sí.

Effects of maternal protein supplementation and inclusion of rumen-protected fat in the finishing diet on nutrient digestibility and expression of intestinal genes in Nellore steers

The study aimed to evaluate nutrient digestibility and intestine gene expression in the progeny from cows supplemented during gestation and fed diets with or without rumen-protected fat (RPF) in the feedlot. Forty-eight Nellore steers, averaging 340 kg, were housed in individual pens and allotted in a completely randomized design using a 2 × 2 factorial arrangement (dams nutrition × RPF). Cows' supplementation started after 124 ± 21 days of gestation. The feedlot lasted 135 days and diets had the inclusion of zero or 6% of RPF. Digestibility was evaluated by total feces collection. Steers were slaughtered using the concussion technique and samples of pancreas and small intestine were collected immediately after the slaughter to analyze α-amylase activity, and the expression of SLC5A1, CD36, and CCK and villi morphometry. Feeding RPF increased nutrients digestibility (p < 0.01). There was no effect of maternal nutrition on digestibility and α-amylase activity in steers (p > 0.05). Duodenal expression of SLC5A1, CD36, and CCK increased in the progeny from restricted cows. In conclusion, protein restriction during mid to late gestation of dams has long-term effects on small-intestine length and on expression of membrane transporters genes in the duodenum of the progeny. However, maternal nutrition does not affect digestibility in the feedlot.

Cholecystokinin-From Local Gut Hormone to Ubiquitous Messenger

Cholecystokinin (CCK) was discovered in 1928 in jejunal extracts as a gallbladder contraction factor. It was later shown to be member of a peptide family, which are all ligands for the CCK₁ and CCK₂ receptors. CCK peptides are known to be synthetized in small intestinal endocrine I-cells and cerebral neurons. But in addition, CCK is expressed in several endocrine glands (pituitary cells, thyroid C-cells, pancreatic islets, the adrenals, and the testes); in peripheral nerves; in cortical and medullary kidney cells; in cardial myocytes; and in cells of the immune system. CCK peptides stimulate pancreatic enzyme secretion and growth, gallbladder contraction, and gut motility, satiety and inhibit acid secretion from the stomach. Moreover, they are major neurotransmitters in the brain and the periphery. CCK peptides also stimulate calcitonin, insulin, and glucagon secretion, and they may act as natriuretic peptides in the kidneys. CCK peptides are derived from proCCK with a C-terminal bioactive YMGWMDFamide sequence, in which the Y-residue is partly O-sulfated. The plasma forms are CCK-58, -33, -22, and -8, whereas the small CCK-8 and -5 are potent neurotransmitters. Over the last decades, CCK expression has also been encountered in tumors (neuroendocrine tumors, cerebral astrocytomas, gliomas, acoustic neuromas, and specific pediatric tumors). Recently, a metastastic islet cell tumor was found to cause a specific CCKoma syndrome, suggesting that circulating CCK may be a useful tumor marker.

Genome-wide profiling of long non-coding RNA expression patterns in the EGFR-TKI resistance of lung adenocarcinoma by microarray

Mutations in the epidermal growth factor receptor (EGFR) make lung adenocarcinoma cells sensitive to EGFR tyrosine kinase inhibitors (TKIs). Long-term cancer therapy may cause the occurrence of acquired resistance to EGFR TKIs. Long non-coding RNAs (lncRNAs) play important roles in tumor formation, tumor metastasis and the development of EGFR-TKI resistance in lung cancer. To gain insight into the molecular mechanisms of EGFR-TKI resistance, we generated an EGFR-TKI-resistant HCC827-8-1 cell line and analyzed expression patterns by lncRNA microarray and compared it with its parental HCC827 cell line. A total of 1,476 lncRNA transcripts and 1,026 mRNA transcripts were dysregulated in the HCC827‑8-1 cells. The expression levels of 7 chosen lncRNAs were validated by real-time quantitative PCR. As indicated by functional analysis, several groups of lncRNAs may be involved in the bio-pathways associated with EGFR-TKI resistance through their cis- and/or trans‑regulation of protein-coding genes. Thus, lncRNAs may be used as novel candidate biomarkers and potential targets in EGFR-TKI therapy in the future.

Glucagon-like peptide-1 and cholecystokinin production and signaling in the pancreatic islet as an adaptive response to obesity

Precise control of blood glucose is dependent on adequate β‐cell mass and function. Thus, reductions in β‐cell mass and function lead to insufficient insulin production to meet demand, and result in diabetes. Recent evidence suggests that paracrine signaling in the islet might be important in obesity, and disruption of this signaling could play a role in the pathogenesis of diabetes. For example, we recently discovered a novel islet incretin axis where glucagon‐like peptide‐1 regulates β‐cell production of another classic gut hormone, cholecystokinin. This axis is stimulated by obesity, and plays a role in enhancing β‐cell survival. In the present review, we place our observations in the wider context of the literature on incretin regulation in the islet, and discuss the potential for therapeutic targeting of these pathways.

Exploring the association between a cholecystokinin promoter polymorphism (rs1799923) and posttraumatic stress disorder in combat veterans

BACKGROUND

Cholecystokinin (CCK) is a neuropeptide that has been implicated in understanding the acquisition and extinction of fear. Research on CCK in anxiety has primarily focused on understanding panic attacks and panic disorder. Emerging data suggests that CCK may also hold promise in understanding the development and maintenance of posttraumatic stress disorder (PTSD).

METHOD

The present study examined whether a single nucleotide polymorphism in the promoter region of the CCK gene (C>T; rs1799923) was associated with an increased prevalence of PTSD as well as with severity of PTSD symptoms among a sample of 457 combat veterans.

RESULTS

Results demonstrated that participants with either the heterozygous or homozygous T allele had an increased prevalence of PTSD relative to participants with the CC genotype (OR=2.17; 95% CI [1.37-3.43]).

LIMITATIONS

The relatively small sample size precluded examination of racial/ethnic differences. Findings were also limited by the absence of a systematic assessment of comorbid anxiety psychopathology.

CONCLUSIONS

These data offer preliminary evidence supporting an association between the rs1799923 polymorphism in the CCK gene and PTSD. Additional research is needed to better understand the nature of this relationship.

Glucagon-Like Peptide-1 Regulates Cholecystokinin Production in β-Cells to Protect From Apoptosis

Cholecystokinin (CCK) is a classic gut hormone that is also expressed in the pancreatic islet, where it is highly up-regulated with obesity. Loss of CCK results in increased β-cell apoptosis in obese mice. Similarly, islet α-cells produce increased amounts of another gut peptide, glucagon-like peptide 1 (GLP-1), in response to cytokine and nutrient stimulation. GLP-1 also protects β-cells from apoptosis via cAMP-mediated mechanisms. Therefore, we hypothesized that the activation of islet-derived CCK and GLP-1 may be linked. We show here that both human and mouse islets secrete active GLP-1 as a function of body mass index/obesity. Furthermore, GLP-1 can rapidly stimulate β-cell CCK production and secretion through direct targeting by the cAMP-modulated transcription factor, cAMP response element binding protein (CREB). We find that cAMP-mediated signaling is required for Cck expression, but CCK regulation by cAMP does not require stimulatory levels of glucose or insulin secretion. We also show that CREB directly targets the Cck promoter in islets from obese (Leptin(ob/ob)) mice. Finally, we demonstrate that the ability of GLP-1 to protect β-cells from cytokine-induced apoptosis is partially dependent on CCK receptor signaling. Taken together, our work suggests that in obesity, active GLP-1 produced in the islet stimulates CCK production and secretion in a paracrine manner via cAMP and CREB. This intraislet incretin loop may be one mechanism whereby GLP-1 protects β-cells from apoptosis.

Cholecystokinin Levels in Prohormone Convertase 2 Knock-out Mouse Brain Regions Reveal a Complex Phenotype of Region-specific Alterations

Prohormone convertase 2 is widely co-localized with cholecystokinin in rodent brain. To examine its role in cholecystokinin processing, cholecystokinin levels were measured in dissected brain regions from prohormone convertase 2 knock-out mice. Cholecystokinin levels were lower in hippocampus, septum, thalamus, mesencephalon, and pons in knock-out mice than wild-type mice. In cerebral cortex, cortex-related structures and olfactory bulb, cholecystokinin levels were higher than wild type. Female mice were more affected by the loss of prohormone convertase 2 than male mice. The decrease in cholecystokinin levels in these brain regions shows that prohormone convertase 2 is important for cholecystokinin processing. Quantitative polymerase chain reaction measurements were performed to examine the relationship between peptide levels and cholecystokinin and enzyme expression. They revealed that cholecystokinin and prohormone convertase 1 mRNA levels in cerebral cortex and olfactory bulb were actually lower in knock-out than wild type, whereas their expression in other brain regions of knock-out mouse brain was the same as wild type. Female mice frequently had higher expression of cholecystokinin and prohormone convertase 1, 2, and 5 mRNA than male mice. The loss of prohormone convertase 2 alters CCK processing in specific brain regions. This loss also appears to trigger compensatory mechanisms in cerebral cortex and olfactory bulb that produce elevated levels of cholecystokinin but do not involve increased expression of cholecystokinin, prohormone convertase 1 or 5 mRNA.

Roles for USF-2 in lung cancer proliferation and bronchial carcinogenesis

The upstream stimulatory factors USF-1 and USF-2 dimerize to regulate transcription through E-box motifs in target genes. Although widely expressed, they can mediate tissue-specific transcription and we previously reported that USF-2 can enhance transcription of arginine vasopressin, a neuropeptide growth factor in small cell lung cancer. Here we determine the expression and role of USF-2 in lung cancer subtypes and examine USF-2 distribution in the bronchial epithelium. For a panel of 12 cell lines and 10 frozen human tumour samples, immunoblotting demonstrated that USF-2 expression was more frequent and abundant in small cell lung cancer than in non-small cell lung cancer. An immunohistochemical study of 108 formalin-fixed and paraffin-embedded human samples was undertaken to localize USF-2 expression and included 44 small cell and 32 non-small cell lung cancers, and 32 samples with bronchial dysplasia. USF-2 was restricted to ciliated cells in normal bronchial epithelium, but was more strongly expressed in dysplastic epithelium (72%) and certain lung cancer types, including small cell lung cancer (71%), squamous cell carcinoma (69%) and a large cell neuroendocrine carcinoma, but was less common in adenocarcinoma (11%). In a small series, expression was assessed adjacent to positively staining tumours; in phenotypically normal bronchial tissues, USF-2 was more highly expressed at 1 cm than at 5 cm from the tumour. Transient USF-2 overexpression in non-small cell lung cancer cell lines significantly stimulated in vitro cell proliferation; this response was most apparent for NCI-H460 (p < 0.005), reducing the mean cell doubling time from 19 to 16 h. Dominant-negative USF-2 mutants had no significant effect on cell growth. Taken together, these data suggest that USF-2 represents a relatively early molecular marker for the development of bronchial dysplasia and non-adenocarcinoma lung cancer. USF may also play a role in bronchial carcinogenesis, perhaps through promoting cell proliferation, although the genes through which this is regulated remain to be determined.

Enteroendocrine cell expression of a cholecystokinin gene construct in transgenic mice and cultured cells

CCK is predominantly expressed in subsets of endocrine cells in the intestine and neurons in the brain. We evaluated the expression of a CCK gene construct in transgenic mice and cultured cells to identify a genomic region that directs correct tissue- and cell-specific expression in enteroendocrine cells. The CCKL1 transgene contained 6.4 kb of mouse Cck fused to lacZ. Expression was evaluated in three transgenic lines (J11, J12, J14) by measurement of beta-galactosidase in tissue homogenates and frozen sections. Correct tissue-specific expression was observed, with beta-galactosidase activity detected in intestine and brain. However, there were differences seen in cell-specific expression in the intestine. Line J14 exhibited expression in CCK-endocrine cells, with expressing cells arising at the normal time during fetal development. However, transgene expression in line J12 intestine was limited to neurons of the enteric nervous system, which reflect an early fetal expression pattern for CCK. Analysis of an additional 15 transgenic founder mice demonstrated intestinal expression in 40% of transgenics, with expressing mice following either an endocrine cell pattern or a neuronal pattern in approximately equal numbers. CCKL1 transfection analysis in cultured cells also demonstrated enteroendocrine cell expression, with 100-fold enhanced activity in the enteroendocrine cell line STC-1 compared with nonendocrine cell lines. The results suggest that the minimal cis-regulatory DNA elements necessary for appropriate CCK expression in enteroendocrine cells reside within the 6.4-kb mouse genomic fragment.

Polymorphisms of the cholecystokinin gene promoter region in suicide victims in Japan

Cholecystokinin (CCK), a neurotransmitter in the central nervous system (CNS), co-exists in a large portion of A10 dopamine neurons to exert some effect on dopamine behavior. The aim of this study was to determine whether any association exists between the genotype of CCK gene promoter regions (-45C/T and -196G/A) and suicidal behavior. Genotypes and allele frequencies of CCK -45C/T and -196G/A were analyzed using polymerase chain reaction (PCR) followed by single-strand conformational polymorphism (SSCP) analysis on the genomic DNA from selected suicide victims (N=154) and from control subjects (N=328). Statistical analysis was performed using the Mantel-Haesnzel chi2-test and multiple logistic regression analysis with distinction of gender. An association between CCK -196G/A polymorphism and suicidal behavior in Japanese males was confirmed by statistical analysis (Odds ratio: 3.462, 95% CI: 1.128-10.626, P=0.038 by multiple logistic regression analysis). However, a significant association between CCK -196G/A polymorphism and suicidal behavior was not discovered in females. The polymorphism of the CCK gene promoter region was found to represent a susceptibility factor for suicidal behavior in Japanese males.

GSK-3beta reduces cAMP-induced cholecystokinin gene expression by inhibiting CREB binding

The cAMP signaling pathway stimulates cholecystokinin (CCK) gene transcription via CREB binding to a cAMP response element (CRE). In the present study we examined the function of glycogen synthase kinase-3beta (GSK-3beta) on cAMP-induced CCK gene transcription. Co-transfection of GSK-3beta reduced the cAMP-induced CCK promoter activity with approximately 80% and approximately 60% in SK-N-MC and PC12 cells, respectively. Binding of in vitro translated CREB to the CCK CRE(-80) promoter element was reduced following incubation with recombinant GSK-3beta. Finally, mutation of serine-129, which is a phosphorylation site for GSK-3beta, did not abolish cAMP-induced CREB-dependent transcription, and cAMP-mediated GAL4-CREB transcription was unaffected by co-transfection with GSK-3beta. We conclude that GSK-3beta regulates cAMP-induced CCK transcription by reducing CREB binding to the CRE(-80) element in the CCK promoter.

KCl and forskolin synergistically up-regulate cholecystokinin gene expression via coordinate activation of CREB and the co-activator CBP

Cholecystokinin (CCK) is one of the most abundant peptide transmitters in the mammalian brain. Despite the physiological significance of CCK expression in long-term memory and psychiatric disorders, little is known about the factors that regulate the expression of CCK peptides. Here, we report that KCl and forskolin synergistically increase CCK gene transcription via protein kinase A (PKA) and extracellular signal-regulated kinase (ERK) signalling pathways, activating cAMP response element-binding protein (CREB) associated with the CRE(- 80) element of the CCK promoter. Whereas, CREB Ser133 phosphorylation was essential for transcriptional activation, the synergistic stimulation was not correlated to the level of Ser133 phosphorylation, indicating that recruitment and/or activation of additional downstream factors were required for maximal stimulation. Transcriptional activation was reduced by co-expression of adenovirus 12S E1A, that inhibits binding of CREB-binding protein (CBP) to CREB. Moreover GAL4-CREB-DIEDML, which mediates the phosphorylation-independent binding of CBP, and the C-terminal domain of CBP was synergistically activated by forskolin and KCl. Taken together the results imply that neuronal CCK gene transcription is regulated by the cumulative action of calcium and cAMP via stimulation of the PKA and ERK signalling pathways and that synergy is accomplished by the coordinate activation of CREB and CBP.

Cholecystokinin, cholecystokinin-A receptor and cholecystokinin-B receptor gene polymorphisms in Parkinson's disease

Cholecystokinin modulates the release of dopamine and dopamine-related behaviours in the mesolimbic pathway, where cholecystokinin and dopamine coexist in dopaminergic neurones. Because cholecystokinin and its receptors (A and B) have a functional interaction with dopaminergic neurotransmission, alterations in them may constitute a predisposition for Parkinson's disease. We performed a case-control study to investigate the association between the cholecystokinin system and Parkinson's disease using genetic markers for three genes: cholecystokinin and its two receptors (A and B). One hundred and sixty patients with Parkinson's disease and 160 controls, matched for age, gender, ethnic origin and area of residence, were recruited. Cholecystokinin -45C>T, cholecystokinin-A receptor 779T>C and cholecystokinin-B receptor 1550G>A gene polymorphisms were studied using polymerase chain reaction-restriction fragment length polymorphism analyses. These three gene polymorphisms showed no correlation with risk of Parkinson's disease; however, the cholecystokinin CT/TT genotype was associated with a 4.429-fold increased risk for visual hallucinations in Parkinson's disease. Cholecystokinin-A receptor and B receptor polymorphisms, considered alone, showed no correlation with hallucinations in Parkinson's disease; however, a combined effect was found in patients with hallucinations harboring both the cholecystokinin CT/TT and cholecystokinin-A receptor TC/CC genotypes. Parkinson's disease patients harboring this genotype have a 5.922-fold increased risk for developing visual hallucinations. These results suggest that, in Chinese, visual hallucinations in Parkinson's disease are associated with cholecystokinin -45C>T polymorphism, and this association was still observed in the presence of the cholecystokinin-A receptor TC/CC genotype, indicating a possible interaction of these two genes in the visual hallucinogenesis in Parkinson's disease.

Transcriptional activities of cholecystokinin promoter haplotypes and their relevance to panic disorder susceptibility

We previously identified a polymorphic compound short tandem repeat (STR) in the 5'-regulatory region of the cholecystokinin (CCK) gene, and showed that when the STRs were classified into three groups based on length and linkage disequilibrium behavior with neighboring variants, the medium class allele was significantly associated with panic disorder. The present study examined the transcriptional activity of the CCK promoter construct containing the STR and downstream -188A/G variation. The STRs acted as transcriptional repressors with a similar potency among the three classes, but the long (L) class STR exhibited a synergistic effect on decreasing promoter activity when combined with -188G. The haplotype composed of the L class of STR and -188G was significantly less frequent in panic disorder (P = 0.0032; odds ratio, 95% confidence interval = 0.06, 0.01-0.69). These results suggest that the L-(-188G) haplotype may act as a protective factor against panic by reducing the expression of anxiogenic CCK.

Age-related changes in CREB binding protein immunoreactivity in the cerebral cortex and hippocampus of rats

Although the role of cAMP-response-element-binding protein (CREB) binding protein (CBP) in the neuroprotective mechanisms has been the focus of many studies, very little is known about the expression or function of CBP in aged brains. We have therefore examined age-related changes in CBP expression in the cerebral cortex and hippocampus with an immunohistochemical technique. In the cerebral cortex, the distribution patterns were not different between adult and aged groups, but the staining intensity of CBP was significantly decreased in aged rats. In the hippocampus, a distinct immunoreactivity pattern was observed in the CA1-3 areas and dentate gyrus. CBP immunoreactivity was significantly deceased in the pyramidal layer of CA1-3 regions in aged hippocampus. In the dentate gyrus of aged rats, significant decreases were also found in the granule cell layer and polymorphic layer. The first demonstration of age-related decreases in CBP expression in the cerebral cortex and hippocampus may provide useful data for investigating the pathogenesis of age-related neurodegenerative diseases and depression.

Regulation of gene promoters of hypothalamic peptides

In order to fulfill their roles in neuroendocrine regulation, specific hypothalamic neurons are devoted to produce and deliver biologically active peptides to the pituitary gland. The biosynthesis and release of peptides are strictly controlled by afferents to these hypothalamic neurons. Cell-specific expression and biosynthetic regulation largely relies on transcription from the gene promoter for which the 5(')-flanking regions of the peptidergic genes contain essential elements. Cell-specific transcription factors employ these regulatory elements to exert their control over the expression of the peptidergic gene. This article explores the properties of regulatory elements of the major hypothalamic peptides, somatostatin, growth hormone-releasing hormone, gonadotropin-releasing hormone, thyrotropin-releasing hormone, corticotropin-releasing hormone, vasopressin and oxytocin, and the transcription factors acting on them. These transcription factors are often endpoints of signal transduction pathways that can be activated by neurotransmitters or steroid hormones. Others are essential to provide cell-specific expression of the peptidergic gene during development and mature regulation.

Association study of the short tandem repeat in the 5' upstream region of the cholecystokinin gene with mood disorders in the Japanese population

We have recently identified a novel polymorphic short tandem repeat (STR) in the 5' upstream region of the cholecystokinin (CCK) gene and reported its association with panic disorder. A linkage study of affective disorder showed a modest linkage signal on the short arm of chromosome 3, the location of the CCK gene. Furthermore, clinical comorbidity of depression and anxiety disorders have been documented. In the present study, we examined a possible association of the CCK STR with mood disorders. We genotyped 165 subjects with mood disorders consisting of unipolar and bipolar disorders and 253 control samples. However, no significant allelic associations were detected between the STR and either the combined mood disorders (P = 0.885), the unipolar group (P = 0.296), or the bipolar group (P = 0.605). These data suggest that the CCK promoter STR is unlikely to have a major genetic effect on the development of mood disorders in the Japanese population.

Possible association of a cholecystokinin promoter variant to schizophrenia

Several lines of research indicate a cholecystokinin (CCK) deficit in schizophrenia patients. A C to T substitution was found in the promoter region of the CCK gene. We investigated this promoter variant in patients with schizophrenia and geographically-matchedcontrols. The T allele was detected in 24% of the 85 schizophrenics and 16% of the 247 controls. No significant difference in the T allele frequency was found between patients and controls (chi(2) = 2.77, P > 0.1). The schizophrenia sample was analyzed further along the dimensions of positive and negative symptoms. The patients with prominent negative symptoms presented a statistically significant association to the T allele (chi(2) = 4.13, P < 0.04). However, the significance disappeared after the Bonferroni correction (P > 0.15). Since the case-control analysis may present incorrect ethnic match between cases and controls, we applied the family-based tests to verify the above findings. Both transmission disequilibrium test (TDT; chi(2) = 5.33, P < 0.025 in 12 trios) and haplotype relative risk (HRR; chi(2) = 3.844, P < 0.05 in 60 trios) indicated a significantly high transmission of T allele to schizophrenia offspring probands from their parents. While our family-based tests seem to support the CCK involvement in schizophrenia, no definite conclusion can be drawn based on such a small sample size. This preliminary finding is subjected to future investigations.

Signal transductions induced by bone morphogenetic protein-2 and transforming growth factor-beta in normal human osteoblastic cells

Transforming growth factor beta (TGF-beta) activates Ras/MAPK signaling in many cell types. Because TGF-beta and BMP-2 exert similar effects, we examined if this signaling is stimulated by both factors and analyzed the relationship between this signaling and the Smads in osteoblasts. BMP-2 and TGF-beta stimulated Ras, MAPK, and AP-1 activities. The DNA binding activities of c-Fos, FosB/Delta FosB, Fra-1, Fra-2, and JunB were up-regulated whereas JunD activity was decreased. c-Fos, FosB/Delta FosB, and JunB were associated with Smad4. The stimulation of AP-1 by BMP-2 and TGF-beta was dependent on Smad signaling, and anti-Smad4 antibody interfered with AP-1 activity. Thus, BMP-2 and TGF-beta activate both Ras/MAPK/AP-1 and Smad signaling in osteoblasts with Smads modulating AP-1 activity. To determine the roles of MAPK in BMP-2 and TGF-beta function, we analyzed the effect of ERK and p38 inhibitors on the regulation of bone matrix protein expression and JunB and JunD levels by these two factors. ERK and p38 mediated TGF-beta suppression of osteocalcin and JunD as well as stimulation of JunB. p38 was essential in BMP-2 up-regulation of type I collagen, fibronectin, osteopontin, osteocalcin, and alkaline phosphatase activity whereas ERK mediated BMP-2 stimulation of fibronectin and osteopontin. Thus, ERK and p38 differentially mediate TGF-beta and BMP-2 function in osteoblasts.

Cholecystokinin gene transcription: promoter elements, transcription factors and signaling pathways

Cholecystokinin (CCK) is a neuropeptide expressed in the small intestine and in the central and peripheral nervous system. CCK gene expression is both spatially and temporally regulated. In neurons CCK production is increased by growth factors, cyclic adenosine 3', 5'-monophosphate (cAMP), dopamine, estrogen, and injury situations, while intestinal CCK expression is mainly regulated by food intake. The function of the proximal CCK promoter has been examined by transfection of human CCK-CAT reporter constructs in cultured cells, DNase I footprinting and gel shift assays. These studies have led to the identification of regulatory elements and transcription factors important for basal and stimulated gene expression and depicted the signaling pathways involved in growth factor and cAMP induced CCK transcription. The review outlines the current knowledge of the regulation of CCK transcription and describes the role of putative transcription factors in tissue-specific CCK gene expression.

Identification of a compound short tandem repeat stretch in the 5'-upstream region of the cholecystokinin gene, and its association with panic disorder but not with schizophrenia

The cholecystokinin gene (CCK) is thought to play a role in the pathogenesis of both panic disorder and schizophrenia. In this study, we have extended the 5'-upstream sequence of the CCK gene, and identified a compound short tandem repeat (STR), located approximately -2.2 to -1.8 kb from the cap site. This STR was found to be polymorphic with ten different allele lengths. Case-control studies using 73 panic patients, 305 schizophrenics and 252 controls showed a significant allelic association with panic disorder (P = 0.025), but not with schizophrenia. Dividing the STR alleles into three classes according to length, Long (L), Medium (M) and Short (S), produced strong genotypic (MM) (nominal P = 0.0014) and allelic (M) (nominal P = 0.0079) associations with panic disorder. screening the newly extended promoter region detected not only the previously identified -36c>t and -188a>g single nucleotide polymorphisms (SNPs) but a new rare snp, -345g>C. Neither of the former two SNPs showed significant association with either panic disorder or schizophrenia. Haplotypic distributions of the STR and SNPs -188 and -36 were significantly different between panic samples and controls (P = 0.0003). These findings suggest that the novel STR or a nearby variant may confer susceptibility to the development of panic disorder.

No association of CCK and CCK(B) receptor polymorphisms with alcohol dependence

Cholecystokinin (CCK) is the most widely distributed neuropeptide in the central nervous system. One of its several functions is to modulate the release of dopamine in brain areas involved in reinforcement and reward behavior. The aim of this study was to investigate the association of CCK system genes (CCK, CCK(A) and CCK(B) receptor genes) with alcohol dependence using single nucleotide polymorphisms (SNPs) as genetic markers. A total of 257 psychiatrically interviewed Finns were genotyped for CCK (-45C>T), CCK(A) (Val365Ile) and CCK(B) (Val125Ile) receptor polymorphisms. Allele frequencies were compared between 150 unrelated healthy Finnish controls and 107 unrelated alcohol-dependent subjects (DSM-III-R criteria), who were also criminal offenders. The frequency of the CCK -45T allele was not significantly different between controls [0.07] and alcoholics [0.09]. The CCK(B) receptor polymorphism Val125Ile was also not associated with alcoholism and the Ile125 allele frequencies were 0.05 in controls vs. 0.06 in alcohol-dependent subjects. A CCK(A) receptor marker, Val365Ile, was uninformative in this Finnish dataset; all subjects were Val365/Val365 homozygous. The results suggest that CCK -45C>T and CCKBR Val125Ile polymorphisms do not have a major role in alcohol dependence in the population studied. The role of the CCK(A) the receptor in alcohol dependence remains open until additional DNA sequence variants for this gene become available.

Identification of overlapping AP-2/NF-kappa B-responsive elements on the rat cholecystokinin gene promoter

In this study we evaluate both proximal and more distal transcriptional regulation of the 5' flanking region of the rat cholecystokinin gene in transfected GH3 (rat pituitary tumor) cells. Transcriptional activity was measured on the intact (-400 to +73) 5' flanking region of cholecystokinin (CCK), as well as with DNA constructs, which were deleted in both the conventional 5' to 3', as well as an unconventional 3' to 5' direction. Our in vivo studies indicate complex phorbol ester and forskolin interactions in the 10-base pair region between -130 and -140. We conclude, there are at least two transcriptional factors involved in regulation of the rat CCK transcription in this region. In vitro studies utilizing heterologous nuclear (HeLa) extract, as well as purified transcription factors AP-2 and NF-kappa B, identify overlapped AP-2- and NF-kappa B-responsive elements within the 17-base pair sequence between -149 and -134 of the distal 5' flanking region. In this region complex transcriptional regulation occurs, which indicates inhibition of AP-2 CCK promoter complexing by NF-kappa B. Six-point mutations introduced into this sequence prevent AP-2 and NF-kappa B binding to CCK promoter, as well as its transcriptional activation by phorbol ester and forskolin in GH3 cells.

No association or linkage between polymorphisms in the genes encoding cholecystokinin and the cholecystokinin B receptor and panic disorder

Growing animal data implicate cholecystokinin in the regulation of anxiety, while human clinical research confirms the role of cholecystokinin in the provocation of panic attacks. Antipanic medications suppress the ability of cholecystokinin to induce panic attacks, and may alter the expression of the cholecystokinin gene. Thus, there is increased interest in understanding the molecular genetic component of these observations. Recent association studies using persons with panic disorder described some association between polymorphisms in the genes encoding cholecystokinin and the cholecystokinin B-receptor and panic disorder. In this study, we used a family-based design, employing 596 individuals in 70 panic disorder pedigrees, as well as 77 haplotype relative risk 'triads'. Subjects were genotyped for two polymorphisms: the polymorphic microsatellite marker in the CCK-BR locus using PCR-based genotyping and at a single nucleotide polymorphism in the CCK promoter using a fluorescence polarization detection assay, and the data were analyzed for genetic association and linkage. Employing a variety of diagnostic and genetic models, linkage analysis produced no significant lod scores at either locus. Family-based tests of association, the haplotype-based haplotype relative risk statistic and the transmission disequilibrium test, were likewise non-significant. The results reported here provide little support for the role of these polymorphisms in panic disorder.

Control of CCK gene transcription by PACAP in STC-1 cells

The mechanisms by which neuroendocrine stimulants regulate CCK gene transcription are unclear. We examined promoter activation by pituitary adenylate cyclase-activating polypeptide (PACAP), a known CCK secretagogue, in the enteroendocrine cell line STC-1. The promoter region from -70 to -87 bp, relative to the transcriptional start site, contains a composite calcium/cyclic AMP response element (CRE)/activator protein 1 (AP1) site that may bind CRE binding protein (CREB) and AP1. PACAP (with IBMX) stimulated expression of an 87-bp construct 3.35+/-0.36-fold but had no effect on a -70 construct. The effect was blocked by the protein kinase A inhibitor H-89 and by a dominant-negative CREB plasmid. Mutation of the CRE/AP1 site to a canonical CRE site did not affect the response to PACAP, but mutation to a canonical AP1 site prevented it. CREB phosphorylation was increased after PACAP treatment. Electrophoretic mobility shift assay and supershift analysis revealed that CREB and not AP1 bound to the CRE/AP1 site and that PACAP increased the proportion of phosphorylated CREB that was bound. We conclude that PACAP increases CCK gene expression via a cAMP-mediated pathway involving CREB phosphorylation by protein kinase A and activation of a composite CRE/AP1 site.

Function of the C-36 to T polymorphism in the human cholecystokinin gene promoter

Cholecystokinin (CCK) is the most abundant neuropeptide in the mammalian brain, and in man significant quantities are expressed in all regions of the brain.1,2 Therefore, CCK has been implicated in a variety of CNS functions-such as feeding behavior, anxiety, analgesia and memory functions as well as psychiatric disease like panic disorder and schizophrenia (for review, see2,3). Recently, a number of studies have indicated that a C-36 to T transition in the CCK gene promoter Sp1 element4 (Figure 1) is associated with alcoholism and withdrawal symptoms as well as panic disorder.5-7 Moreover, it has been proposed that the polymorphism plays a direct role in the pathogenesis of the disorders by decreasing the expression and synthesis of CCK peptides. The significance of these findings is still unclear and other studies have failed to demonstrate linkage between the polymorphism and alcoholism.8 In this study we examined the function of the C-36 to T transition in transcription of the human CCK gene. We demonstrate that substitution of the C-36 residue causes a slight reduction of Sp1 and Sp3 binding, but this has no effect on transcription in vivo. Moreover, no difference in the response to physiological stimuli was observed. Taken together the results show that the C to T polymorphism does not play a direct role in the pathogenesis of either alcoholism or panic disorder and that a putative association to these disorders is likely to be the result of co-segregation with a linked mutation.

Neuroadaptational changes in DNA binding of stimulatory protein-1 and nuclear factor-kB gene transcription factors during ethanol dependence

To define the molecular basis of ethanol dependence, the changes in gene transcription factor stimulatory protein-1 (SP1) and nuclear factor-kB (NF-kB) DNA binding activities were investigated in the rat cortex and hippocampus during ethanol treatment (15 days) and its withdrawal. It was found that both protracted ethanol treatment and its withdrawal (12, 24, or 72 h) had no effect on NF-kB DNA binding activity in the rat cortex and hippocampus. Time-course studies of the changes in SP1 DNA binding activity during ethanol withdrawal (0, 12, 24, and 72 h) after protracted ethanol exposure indicated that SP1 DNA binding in the rat cortex was significantly decreased at 0 h, and that it remained decreased at 12, 24, and 72 h of withdrawal. On the other hand, SP1 DNA binding activity did not change in the rat hippocampus during ethanol treatment but was significantly decreased at 12, 24, and 72 h of withdrawal. These results suggest the possibility that decreased SP1-dependent gene transcription in the rat cortex and hippocampus may be associated with the molecular mechanisms of ethanol dependence.

Association between polymorphism of the cholecystokinin gene and idiopathic Parkinson's disease

Parkinson's disease (PD) is characterized by major alterations of neurotransmitter activity due to damage of the substantia nigra. Changes in neuropeptide concentration within the basal ganglia may play an important role in the putative dopaminergic-peptidergic interactions associated with the disease. Cholecystokinin (CCK) modulates the release of dopamine in the mesolimbic pathway and affects dopamine-related behavior. We analyzed genetic variations in the CCK gene, in both the coding and promoter region, in order to investigate the role of polymorphism in idiopathic PD. Four polymorphic sites of the CCK gene (-196G/A, -45C/T, 1270C/G, 6662C/T) were found in PD patients and controls. Complete linkage disequilibrium was observed between the -45 locus and the 1270 locus, and also a possible linkage disequilibrium was found between the -45 and -196 loci. A significant difference was found in the distributions of three identified genotypes at the -45 locus between 116 PD patients and 95 age-matched control subjects (chi2 = 7.95, p = 0.018, Bonferroni correction; p = 0.054). In addition, a significant difference was obtained amongst the three genotypic groups at the -45 locus when compared between PD patients who experienced hallucinations (n = 23) and those (n = 93) who did not (chi2 = 8.08, p = 0.018, Bonferroni correction, p = 0.126). Our data suggested that mutations at the -45 locus in the promoter region of the CCK gene may influence vulnerability to hallucinations in PD patients treated with L-dopa.

Genetic association between alcohol withdrawal symptoms and polymorphism of CCK gene promoter

In the central nervous system, cholecystokinin (CCK) is an important neurotransmitter that gives the influences on firings, anxiety, notiception, and dopamine-related behavior. CCK co-exists in the dopaminergic neurons, interacting with dopamine. In this study, we examined the genetic variant -45 C to T substitution of the CCK gene promoter region among 195 healthy Japanese and 174 patients with alcohol withdrawal syndrome (52 delirium tremens, 39 hallucinosis, 20 seizures, and 92 lack of these symptoms) by using polymerase chain reaction-based single-strand conformational polymorphism analysis. Patients with delirium tremens showed a significantly higher frequency of the variant, compared with the controls (chi2 = 4.91, p < 0.03), but patients with other symptoms showed no difference. These data suggested that the individuals possessing allelic mutation (-45T) in the promoter region of the CCK gene might be susceptible to delirium tremens caused by alcohol abuse.

Negative cooperativity between juxtaposed E-box and cAMP/TPA responsive elements in the cholecystokinin gene promoter

The promoter of the cholecystokinin (CCK) gene possesses evolutionary conserved juxtaposed E-box and cAMP/TPA responsive elements (CRE/TRE). We have examined the functional interaction of these two sites. As previously noted, c-Jun/c-Fos heterodimers greatly increase promoter activity through association with the CRE/TRE. Mutation of the E-box enhanced the activation by c-Jun/c-Fos, as well as stimulation by forskolin and bFGF, that acts through the CRE/TRE site. Moreover, c-Jun/c-Fos stimulation was inhibited by co-expression of c-Myc and Max. The results indicate that factors associating with the E-box exhibit a negative cooperative effect on the activation via the CRE/TRE element. We propose that this mechanism plays a significant role in CCK gene transcription and other genes with juxtaposed E-box and CRE/TRE.

No association between C-45T polymorphism in the Sp1 binding site of the promoter region of the cholecystokinin gene and alcoholism

The activity of dopamine-containing neurons in the ventral tegmental area and nucleus accumbens may play a role in alcoholism. Cholecystokinin (CCK) co-exists in a large proportion of A10 dopamine neurons to exert some effect on dopamine-induced behavior. Recently, a C-45T polymorphism was discovered in the Sp1 binding site in the CCK gene promoter region. We investigated an association between the polymorphism and alcoholism in 209 Japanese DSM-III-R alcoholics and 113 Japanese control subjects. The patients and the control subjects had similar allele and genotype frequencies: the T allele frequencies were 0.27 in the patients and 0.28 in the control subjects and the CC, CT, and the TT genotype frequencies 0.53, 0.39, and 0.08 in the alcoholics and 0.53, 0.37, and 0.10 in the control subjects. Frequencies of clinical characteristics of Feighner's criteria for the lifetime diagnosis of alcoholism were not significantly different among the patient groups divided by the genotype. These findings indicate that the polymorphism has no major effect on the etiology of alcoholism.

Distribution of CREB-binding protein immunoreactivity in the adult rat brain

We demonstrate the expression of the co-activator CREB-binding protein (CBP) in the nuclei of a large number of neurons and glial structures in the rat brain and spinal cord. Immunoblotting of nuclear extracts revealed a single band at 265 kDa, the size of CBP. We found that CBP immunoreactivity was localized to cholecystokinin mRNA-expressing neurons in the hippocampus and the thalamus, suggesting that CBP may be involved in long-term memory and modulation of cortical activity. However, CBP-labeling was not ubiquitous, and many brain regions, including several mesencephalic and diencephalic nuclei, showed sparse labeling. Further, the number of neurons displaying intense CBP-labeling varied across animals in some regions, e.g., the hippocampus and the amygdala. Since competition for limited amounts of CBP and CBP-related molecules has been shown to be important for the integration of intracellular signaling pathways with transcriptional regulation, the present results suggest that varying endogenous levels of CBP in post-mitotic neurons is an important parameter in neuronal transcriptional regulation.

The new biology of gastrointestinal hormones

The classic concept of gastrointestinal endocrinology is that of a few peptides released to the circulation from endocrine cells, which are interspersed among other mucosal cells in the upper gastrointestinal tract. Today more than 30 peptide hormone genes are known to be expressed throughout the digestive tract, which makes the gut the largest endocrine organ in the body. Moreover, development in cell and molecular biology now makes it feasible to describe a new biology for gastrointestinal hormones based on five characteristics. 1) The structural homology groups the hormones into families, each of which is assumed to originate from a common ancestral gene. 2) The individual hormone gene is often expressed in multiple bioactive peptides due to tandem genes encoding different hormonal peptides, alternative splicing of the primary transcript, or differentiated processing of the primary translation product. By these mechanisms, more than 100 different hormonally active peptides are produced in the gastrointestinal tract. 3) In addition, gut hormone genes are widely expressed, also outside the gut. Some are expressed only in neuroendocrine cells, whereas others are expressed in a multitude of different cells, including cancer cells. 4) The different cell types often express different products of the same gene, "cell-specific expression." 5) Finally, gastrointestinal hormone-producing cells release the peptides in different ways, so the same peptide may act as an acute blood-borne hormone, as a local growth factor, as a neurotransmitter, and as a fertility factor. The new biology suggests that gastrointestinal hormones should be conceived as intercellular messengers of general physiological impact rather than as local regulators of the upper digestive tract.

Possible association of a cholecystokinin promotor polymorphism (CCK-36CT) with panic disorder

We searched for mutations in the CCK gene in panic disorder with single-strand conformational polymorphism (SSCP) analysis of the three exons and promotor region of the gene. We found a C-->T transition at position -36 (CCK(-36C-->T)) in a GC box, a binding site for transcription factor Sp1, in the promotor region. The allele frequency was 0.168 (95% CI, 0.116-0.221) in 98 persons with panic disorder and 0.083 (95% CI, 0.059-0.107) in 247 geographically matched, unscreened controls. A transmission disequilibrium test based on panic disorder as the affected phenotype was nonsignificant (chi2 = 0.93), but when panic disorder or attacks were considered as affected, statistically significant transmission disequilibrium was detected (chi2 = 4.00, P < 0.05). Linkage analysis was uninformative. In exploratory analyses to search for clinical correlations, the "T" allele was found in 59% of 22 persons with panic attacks but not panic disorder, compared with 31% of those who met the criteria for panic disorder. An association between the CCK polymorphism and panic disorder cannot be considered established due to the inconsistencies in the results noted above, but if the provisional association can be replicated, the findings are consistent with CCK(-36C-->T) being a disease-susceptibility allele that alone is neither necessary nor sufficient to cause panic disorder but that increases vulnerability by acting epistatically.

A new genetic variant in the Sp1 binding cis-element of cholecystokinin gene promoter region and relationship to alcoholism

Neuropeptide cholecystokinin (CCK) and the CCK receptors in the central nervous system mediate actions on increasing firings, anxiety, and nociceptions. Furthermore, CCK modulates the release of dopamine and dopamine-related behaviors in the mesolimbic pathway. In our study, genetic variation in the promoter and coding regions of the prepro-CCK gene were analyzed among 66 Japanese, 66 American Whites, 54 Chinese, and 41 Colombian natives. Two nucleotide sequence variants were found: a frequent mutation at nucleotide position -45 C to T involved in core sequence of Sp1 binding cis-element of the promoter region, and a C to T substitution at the 1662 position in intron 2. Analysis for the segregation study in 10 families of twins confirmed codominant heredity of two alleles. Distribution of genotypes and gene frequencies of 66 controls and 108 alcoholics in Japan presented that allelic variant T type in alcoholics was found in higher frequencies than that of controls, and distribution of these genotypes was significantly different between the both groups.

Differential cholecystokinin brain/gut transcription initiation in the rat: evidence for brain-specific start sites

Brain/gut cholecystokinin (CCK) has well-established translational and post-translational differences. By contrast, CCK transcription regulation is reported to be the same in brain and gut. Accordingly, the rat CCK gene has been evaluated for differential brain/gut transcription initiation. Using the 5'-flanking region of the rat CCK gene, DNase I protection assays were performed. We evaluated reporter constructs deleted of the conventional transcription start site in cell culture. Finally, brain and gut mRNA was evaluated using both a reverse transcription serial primer polymerase chain reaction assay as well as rapid amplification of cDNA ends (RACE) analysis. TFIID protein protects against DNase I digestion between -177 and -196 bp. In tissue culture, spontaneous 5'-flanking region transcription initiation occurs until deletion proceeds upstream of -140 bp. RACE analysis performed on mRNA from the rat brain identifies heretofore undescribed transcription initiation at -43 bp 5' as well as at +1,212 (in exon II). These alternative transcription initiation sites are utilized in brain, but not gut. The rat CCK gene has alternative 5'-flanking region transcription initiation sites. These alternative sites are utilized only in the brain. These data may provide insights into how brain and gut respond to their differing physiological demands.

Transcriptional regulation of the human replacement histone gene H3.3B

In contrast to the cell-cycle-dependent histone genes, replacement histone genes are transcribed independently of DNA replication and their expression is upregulated during differentiation. We have investigated the transcriptional regulation of the recently characterized human replacement histone gene H3.3B. Using reporter gene assays of promoter-luciferase gene-constructs, we show that promoter activity largely depends on an intact Oct and CRE/TRE element within the proximal 145 bp of the promoter. DNase I footprinting revealed binding of proteins to a 40-bp region covering these two elements. Band shift experiments identified binding proteins as Oct-1 and factors of the CREB/ATF and AP-1 family, respectively. The unexpected transcriptional regulation of this replacement histone gene is discussed.

Characterization of the cholecystokinin and gastrin genes from the bullfrog, Rana catesbeiana: evolutionary conservation of primary and secondary sites of gene expression

The gastrin and cholecystokinin (CCK) genes, and the complementary DNAs they encode, have been isolated and sequenced from the bullfrog, Rana catesbeiana. The CCK gene promoter region possess the same four well characterized transcriptional control elements as the human CCK gene, namely an E-box, AP-1 binding site, Sp1 site, and TATA box. In contrast, no obvious regulatory motifs are conserved in the gastrin gene. Alignment of the bullfrog preprohormone sequences with other members of the CCK/gastrin peptide family showed that preproCCK has been conserved to a greater degree during evolution than preprogastrin. In mammalian species, gastrin gene expression is typically associated with the antrum, and CCK with the small intestine and brain. However numerous secondary sites of CCK/gastrin gene expression have also been found. RT-PCR showed a high degree of conservation of both primary and secondary sites of CCK/gastrin production between mammals and the bullfrog, with gastrin messenger RNA being detected in the antrum, duodenum, colon, pancreas, brain, and testes, whereas CCK mRNA was observed in the brain, lung, testes, and throughout the length of the small intestine. In situ hybridization using radiolabeled gene specific antisense oligonucleotides uncovered CCK and gastrin messenger RNA in distinct areas of the bullfrog central nervous system and pituitary gland. Notably, the gastrin gene was expressed in the pituitary gland and hypothalamus of the bullfrog, as previously seen in mammals. This highly preserved tissue expression pattern suggests that gastrin plays specific roles in the hypothalamus and pituitary gland that are distinct from those of CCK. Our findings show that in spite of the structural resemblance, bullfrog CCK and gastrin constitute independent neuroendocrine peptide systems.

Cholecystokinin (CCK) release from rat brain slices in vitro is enhanced by agents which elevate intracellular cAMP

Cholecystokinin (CCK) release from rat brain slices in vitro is enhanced by agents which elevate intracellular cAMP. Treatment of several CCK expressing tumor cells in culture with agents which increase intracellular cAMP increased secretion of CCK. The possibility that elevation of cAMP also alters potassium-evoked release of CCK from rat brain slices incubated in vitro was also investigated. Treatment of slices of rat prefrontal cortex and caudate-putamen with 5 microM forskolin plus 0.5 mM IBMX (3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor) caused a significant elevation of potassium-evoked CCK release. That cAMP can increase CCK release in intact brains slices as well as endocrine tumor cells from thyroid, pancreas, pituitary and intestine suggests that cAMP is a common intracellular mediator for the regulation of CCK release.