Down syndrome candidate region 1 increases the stability of the IkappaBalpha protein: implications for its anti-inflammatory effects

Identification of Key Functional Genes and LncRNAs Influencing Muscle Growth and Development in Leizhou Black Goats

Meat yield and quality are important economic traits of livestock. Herein, longissimus dorsi (LD) muscles of Leizhou black goats aged 0, 3, and 6 months were used to identify differentially expressed messenger RNAs (mRNAs) and long non-coding RNAs (lncRNAs) by high-throughput RNA sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to analyze differentially expressed genes. Expression levels of regulator of calcineurin 1 (RCAN1) and olfactory receptor 2AP1 (OR2AP1) were significantly different in LD muscles of goats aged 0, 3, and 6 months, indicating potentially important roles in postnatal muscle development. Differentially expressed lncRNAs and mRNAs were mainly enriched in biological processes and pathways related to cellular energy metabolism, consistent with previous studies. Three lncRNAs, TCONS_00074191, TCONS_00074190, and TCONS_00078361, may play a cis-acting role with methyltransferase-like 11B (METTL11B) genes and participate in the methylation of goat muscle proteins. Some of the identified genes may provide valuable resources for future studies on postnatal meat development in goat muscles.

Cynanchi atrati and Its Phenolic Constituent Sinapic Acid Target Regulator of Calcineurin 1 (RCAN1) to Control Skin Inflammation

Atopic dermatitis (AD) is a common inflammatory skin disorder, and numerous pharmacological approaches are employed to reduce symptoms. Natural products of plant-derived materials have been accepted as complementary therapy for the treatment of a wide range of inflammatory diseases. Cynanchi atrati (CA) is an oriental medicinal herb used in the treatment of acute urinary infection, febrile diseases, and laryngopharyngitis. However, the role of CA root extract in skin inflammation such as AD has not been explored yet. In this study, we examined the possible effect of CA root extract on skin inflammation and evaluated the underlying signaling mechanism using in vitro and in vivo modeling systems. Raw264.7 macrophages were used for in vitro experiments, and an oxazolone-induced AD mouse model was used to evaluate in vivo effects. CA extract significantly inhibited the expression levels of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-1β (IL-1β) in RAW264.7 macrophages. The CA root extract mediated suppression of pro-inflammatory cytokine expression and was associated with the decreased nuclear factor kappa B (NF-κB) gene transcriptional activation. Moreover, CA root extract attenuated the in vivo expression of IL-6 and tumor necrosis factor-α (TNF-α) and ear swelling in the AD mouse models. We also observed that the inhibitory effect of CA root extract on skin inflammation was accompanied by the upregulation of calcineurin 1 (RCAN1) expression, which functions in the inflammatory pathways by suppressing NF-κB signaling. We consistently observed that the immunosuppressive effect of CA root extract in AD was significantly perturbed in the RCAN1 knockout mice. In addition, we isolated a phenolic acid compound, sinapic acid (SA), from the CA root extract and found that SA consistently exerted an immunosuppressive effect in RAW264.7 macrophages by inducing RCAN1 expression. Our results provide the first evidence that CA root extract and its phenolic acid constituent, SA, modulate NF-κB signaling pathways by inducing RCAN1 expression in the skin inflammation process. Thus, we suggest that CA root extract has a therapeutic value for the treatment of AD by targeting endogenous immune regulators.

Down Syndrome Critical Region 1 Reduces Oxidative Stress-Induced Retinal Ganglion Cells Apoptosis via CREB-Bcl-2 Pathway

Purpose

Irreversible retina ganglion cell (RGC) loss is a key process during glaucoma progression. Down syndrome critical region 1 (DSCR1) has been shown to have protective effects against neuronal death. In this study, we aimed to investigate the neuroprotective mechanisms of DSCR1 on RGCs.

Methods

DBA/2J mice and optic nerve crush (ONC) rat model were used for vivo assays. Oxidative stress model of primary RGCs was carried out with in vitro transduction. DSCR1 protein localization was assessed by immunofluorescence. Differential protein expression was validated by Western blot, and gene expression was detected by real-time PCR. TUNEL was used to identify cell apoptosis, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to analyze cell viability.

Results

Significant upregulation of DSCR1 was observed in DBA/2J mice, ONC rat model, and RGCs treated with H₂O₂, reaching peaks at the age of 6 months in DBA/2J mice, 5 days after ONC in rats, and 24 hours after H₂O₂ treatment in RGCs, respectively. DSCR1 was shown to be expressed in the ganglion cell layer. In vitro, overexpressed DSCR1 significantly promoted phosphorylation of cyclic AMP response element binding protein (CREB), B-cell lymphoma 2 (Bcl-2) expression, and RGC survival rate while reducing cleaved caspase 3 expression in H₂O₂-treated RGCs. On the other hand, the opposite effects were shown after knockdown of DSCR1. In addition, silencing of CREB inhibited expression of DSCR1.

Conclusions

Our results suggested that DSCR1 might protect the RGCs against oxidative stress via the CREB–Bcl-2 pathway, which may provide a theoretical basis for future treatments of glaucoma.

Spatiotemporal expression of RCAN1 and its isoform RCAN1-4 in the mouse hippocampus after pilocarpine-induced status epilepticus

Regulator of calcineurin 1 (RCAN1) can be induced by an intracellular calcium increase and oxidative stress, which are characteristic features of temporal lobe epilepsy. Thus, we investigated the spatiotemporal expression and cellular localization of RCAN1 protein and mRNA in the mouse hippocampus after pilocarpine-induced status epilepticus (SE). Male C57BL/6 mice were given pilocarpine hydrochloride (280 mg/kg, i.p.) and allowed to develop 2 h of SE. Then the animals were given diazepam (10 mg/kg, i.p.) to stop the seizures and sacrificed at 1, 3, 7, 14, or 28 day after SE. Cresyl violet staining showed that pilocarpine-induced SE resulted in cell death in the CA1 and CA3 subfields of the hippocampus from 3 day after SE. RCAN1 immunoreactivity showed that RCAN1 was mainly expressed in neurons in the shammanipulated hippocampi. At 1 day after SE, RCAN1 expression became detected in hippocampal neuropils. However, RCAN1 signals were markedly enhanced in cells with stellate morphology at 3 and 7 day after SE, which were confirmed to be reactive astrocytes, but not microglia by double immunofluorescence. In addition, real-time reverse transcriptase–polymerase chain reaction showed a significant upregulation of RCAN1 isoform 4 (RCAN1-4) mRNA in the SE-induced hippocampi. Finally, in situ hybridization with immunohistochemistry revealed astrocytic expression of RCAN1-4 after SE. These results demonstrate astrocytic upregulation of RCAN1 and RCAN1-4 in the mouse hippocampus in the acute and subacute phases of epileptogenesis, providing foundational information for the potential role of RCAN1 in reactive astrocytes during epileptogenesis.

Methylation of RCAN1.4 mediated by DNMT1 and DNMT3b enhances hepatic stellate cell activation and liver fibrogenesis through Calcineurin/NFAT3 signaling

Background: Liver fibrosis is characterized by extensive deposition of extracellular matrix (ECM) components in the liver. RCAN1 (regulator of calcineurin 1), an endogenous inhibitor of calcineurin (CaN), is required for ECM synthesis during hypertrophy of various organs. However, the functional role of RCAN1 in liver fibrogenesis has not yet been addressed. Methods: We induced experimental liver fibrosis in mice by intraperitoneal injection of 10 % CCl4 twice a week. To investigate the functional role of RCAN1.4 in the progression of liver fibrosis, we specifically over-expressed RCAN1.4 in mice liver using rAAV8-packaged RCAN1.4 over-expression plasmid. Following the establishment of the fibrotic mouse model, primary hepatic stellate cells were isolated. Subsequently, we evaluated the effect of RCAN1.4 on hepatic fibrogenesis, hepatic stellate cell activation, and cell survival. The biological role and signaling events for RCAN1 were analyzed by protein-protein interaction (PPI) network. Bisulfite sequencing PCR (BSP) was used to predict the methylated CpG islands in the RCAN1.4 gene promoter. We used the chromatin immunoprecipitation (ChIP assay) to investigate DNA methyltransferases which induced decreased expression of RCAN1.4 in liver fibrosis. Results: Two isoforms of RCAN1 protein were expressed in CCl4-induced liver fibrosis mouse model and HSC-T6 cells cultured with transforming growth factor-beta 1 (TGF-β1). RCAN1 isoform 4 (RCAN1.4) was selectively down-regulated in vivo and in vitro. The BSP analysis indicated the presence of two methylated sites in RCAN1.4 promoter and the downregulated RCAN1.4 expression levels could be restored by 5-aza-2'-deoxycytidine (5-azadC) and DNMTs-RNAi transfection in vitro. ChIP assay was used to demonstrate that the decreased RCAN1.4 expression was associated with DNMT1 and DNMT3b. Furthermore, we established a CCl4-induced liver fibrosis mouse model by injecting the recombinant adeno-associated virus-packaged RCAN1.4 (rAAV8-RCAN1.4) over-expression plasmid through the tail vein. Liver- specific-over-expression of RAN1.4 led to liver function recovery and alleviated ECM deposition. The key protein (a member of the NFAT family of proteins) identified on PPI network data was analyzed in vivo and in vitro. Our results demonstrated that RCAN1.4 over-expression alleviates, whereas its knockdown exacerbates, TGF-β1-induced liver fibrosis in vitro in a CaN/NFAT3 signaling-dependent manner. Conclusions: RCAN1.4 could alleviate liver fibrosis through inhibition of CaN/NFAT3 signaling, and the anti-fibrosis function of RCAN1.4 could be blocked by DNA methylation mediated by DNMT1 and DNMT3b. Thus, RCAN1.4 may serve as a potential therapeutic target in the treatment of liver fibrosis.

LPS-Induced Inflammation Abolishes the Effect of DYRK1A on IkB Stability in the Brain of Mice

Down syndrome is characterized by premature aging and dementia with neurological features that mimic those found in Alzheimer's disease. This pathology in Down syndrome could be related to inflammation, which plays a role in other neurodegenerative diseases. We previously found a link between the NFkB pathway, long considered a prototypical proinflammatory signaling pathway, and the dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A). DYRK1A is associated with early onset of Alzheimer's disease in Down syndrome patients. Here, we sought to determine the role of DYRK1A on regulation of the NFkB pathway in the mouse brain. We found that over-expression of Dyrk1A (on a C57BL/6J background) stabilizes IκBα protein levels by inhibition of calpain activity and increases cytoplasmic p65 sequestration in the mouse brain. In contrast, Dyrk1A-deficient mice (on a CD1 background) have decreased IκBα protein levels with an increased calpain activity and decreased cytoplasmic p65 sequestration in the brain. Taken together, our results demonstrate a role of DYRK1A in regulation of the NFkB pathway. However, decreased IκBα and DYRK1A protein levels associated with an increased calpain activity were found in the brains of mice over-expressing Dyrk1A after lipopolysaccharide treatment. Although inflammation induced by lipopolysaccharide treatment has a positive effect on calpastatin and a negative effect on DYRK1A protein level, a positive effect on microglial activation is maintained in the brains of mice over-expressing Dyrk1A.

Regulator of Calcineurin 1 helps coordinate whole-body metabolism and thermogenesis

Increasing non-shivering thermogenesis (NST), which expends calories as heat rather than storing them as fat, is championed as an effective way to combat obesity and metabolic disease. Innate mechanisms constraining the capacity for NST present a fundamental limitation to this approach, yet are not well understood. Here, we provide evidence that Regulator of Calcineurin 1 (RCAN1), a feedback inhibitor of the calcium-activated protein phosphatase calcineurin (CN), acts to suppress two distinctly different mechanisms of non-shivering thermogenesis (NST): one involving the activation of UCP1 expression in white adipose tissue, the other mediated by sarcolipin (SLN) in skeletal muscle. UCP1 generates heat at the expense of reducing ATP production, whereas SLN increases ATP consumption to generate heat. Gene expression profiles demonstrate a high correlation between Rcan1 expression and metabolic syndrome. On an evolutionary timescale, in the context of limited food resources, systemic suppression of prolonged NST by RCAN1 might have been beneficial; however, in the face of caloric abundance, RCAN1-mediated suppression of these adaptive avenues of energy expenditure may now contribute to the growing epidemic of obesity.

OxInflammation: From Subclinical Condition to Pathological Biomarker

Inflammation is a complex systemic response evolved to cope with cellular injury, either due to infectious agents or, in general, with sporadic events challenging tissue integrity and function. Researchers involved in different fields have the tendency to look at the inflammatory response with different angles, according to their specific interest. Established its complexity, one of the most evident features of the inflammatory response is the generation of a pro-oxidative environment due to the production of high fluxes of pro-oxidant species. This production begins locally, close to the sites of tissue damage or infection, but eventually becomes a chronic challenge for the organism, if the inflammatory response is not properly controlled. In this review, we focus on this specific aspect of chronic, low-level sub-clinical inflammatory response. We propose the term "OxInflammation" as a novel operative term describing a permanent pro-oxidative feature that interact, in a positive feed-back manner, to a not yet clinically detectable inflammatory process, leading in a long run (chronically) to a systemic/local damage, as a consequence of the cross talk between inflammatory, and oxidative stress mediators. Therefore, it could be useful to analyze inflammatory markers in pathologies where there is an alteration of the redox homeostasis, although an inflammatory status is not clinically evident.

Regulator of calcineurin 1 differentially regulates TLR-dependent MyD88 and TRIF signaling pathways

Toll-like receptors (TLRs) recognize the conserved molecular patterns in microorganisms and trigger myeloid differentiation primary response 88 (MyD88) and/or TIR-domain-containing adapter-inducing interferon-β (TRIF) pathways that are critical for host defense against microbial infection. However, the molecular mechanisms that govern TLR signaling remain incompletely understood. Regulator of calcineurin-1 (RCAN1), a small evolutionarily conserved protein that inhibits calcineurin phosphatase activity, suppresses inflammation during Pseudomonas aeruginosa infection. Here, we define the roles for RCAN1 in P. aeruginosa lipopolysaccharide (LPS)-activated TLR4 signaling. We compared the effects of P. aeruginosa LPS challenge on bone marrow-derived macrophages from both wild-type and RCAN1-deficient mice and found that RCAN1 deficiency increased the MyD88-NF-κB-mediated cytokine production (IL-6, TNF and MIP-2), whereas TRIF-interferon-stimulated response elements (ISRE)-mediated cytokine production (IFNβ, RANTES and IP-10) was suppressed. RCAN1 deficiency caused increased IκBα phosphorylation and NF-κB activity in the MyD88-dependent pathway, but impaired ISRE activation and reduced IRF7 expression in the TRIF-dependent pathway. Complementary studies of a mouse model of P. aeruginosa LPS-induced acute pneumonia confirmed that RCAN1-deficient mice displayed greatly enhanced NF-κB activity and MyD88-NF-κB-mediated cytokine production, which correlated with enhanced pulmonary infiltration of neutrophils. By contrast, RCAN1 deficiency had little effect on the TRIF pathway in vivo. These findings demonstrate a novel regulatory role of RCAN1 in TLR signaling, which differentially regulates MyD88 and TRIF pathways.

Regulator of calcineurin 1 modulates vascular contractility and stiffness through the upregulation of COX-2-derived prostanoids

Cyclooxygenase-2 (COX-2) derived-prostanoids participate in the altered vascular function and mechanical properties in cardiovascular diseases. We investigated whether regulator of calcineurin 1 (Rcan1) participates in vascular contractility and stiffness through the regulation of COX-2. For this, wild type (Rcan1^+/+) and Rcan1-deficient (Rcan1^-/-) mice untreated or treated with the COX-2 inhibitor rofecoxib were used. Vascular function and structure were analysed by myography. COX-2 and phospo-p65 expression were studied by western blotting and immunohistochemistry and TXA₂ production by ELISA. We found that Rcan1 deficiency increases COX-2 and IL-6 expression and NF-κB activation in arteries and vascular smooth muscle cells (VSMC). Adenoviral-mediated re-expression of Rcan1.4 in Rcan1^-/- VSMC normalized COX-2 expression. Phenylephrine-induced vasoconstrictor responses were greater in aorta from Rcan1^-/- compared to Rcan1^+/+ mice. This increased response were diminished by etoricoxib, furegrelate, SQ 29548, cyclosporine A and parthenolide, inhibitors of COX-2, TXA₂ synthase, TP receptors, calcineurin and NF-κB, respectively. Endothelial removal and NOS inhibition increased phenylephrine responses only in Rcan1^+/+ mice. TXA₂ levels were greater in Rcan1^-/- mice. In small mesenteric arteries, vascular function and structure were similar in both groups of mice; however, vessels from Rcan1^-/- mice displayed an increase in vascular stiffness that was diminished by rofecoxib. In conclusion, our results suggest that Rcan1 might act as endogenous negative modulator of COX-2 expression and activity by inhibiting calcineurin and NF-kB pathways to maintain normal contractility and vascular stiffness in aorta and small mesenteric arteries, respectively. Our results uncover a new role for Rcan1 in vascular contractility and mechanical properties.

MicroRNA-34a targets regulator of calcineurin 1 to modulate endothelial inflammation after fetal cardiac bypass in goat placenta

INTRODUCTION

Placental dysfunction characterized by vascular endothelial inflammation is one of the most notable responses to fetal cardiac bypass. Regulator of calcineurin 1 (RCAN1) is an important regulator of inflammatory responses. MicroRNAs (miRNAs) are essential post-transcriptional modulators of gene expression, and miRNA-34a (miR-34a) was showed to activate vascular endothelial inflammation. We hypothesized that miR-34a may be a key regulator of placental dysfunction after fetal cardiac bypass.

METHODS

We evaluated miRNA expression in goat placentas via small RNA sequencing, quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. Expression of miRNA target genes was determined via bioinformatics analyses and dual luciferase reporter assays. Furthermore, human umbilical vein endothelial cells (HUVECs) were transfected with miR-34a or a control sequence. The RCAN1, nuclear factor of activated T-cells (NFATC1) and nuclear factor kappa-B (NF-κB) levels in HUVECs and placentas were evaluated via Western blot and qRT-PCR.

RESULTS

We demonstrated that miR-34a was highly enriched in goat placenta after cardiopulmonary bypass. Moreover, RCAN1 was identified as a novel direct target of miR-34a. Transfection of miR-34a led to decreased RCAN1 expression and increased NFATC1 and NF-κB expression in HUVECs. Conversely, inhibition of miR-34a rescued RCAN1 expression and reduced NFATC1 and NF-κB expression in HUVECs.

CONCLUSIONS

We demonstrated a remarkable role of miR-34a as a regulator of NFATC1-associated placental inflammation through direct targeting of RCAN1. MiR-34a could serve as a novel therapeutic target for limiting the progression of placental inflammation after fetal cardiac bypass.

RCAN1 deficiency protects against Salmonella intestinal infection by modulating JNK activation

OBJECTIVE

RCAN1 (regulator of calcineurin 1) has been shown to be involved in various physiological and pathological processes. However, the biological implications of RCAN1 during gastrointestinal tract infection remain unclear. In this study, we tried to determine the role of RCAN1 in acute Salmonella infectious colitis.

METHODS

Wild type and RCAN1-deficient mice or macrophages were used to characterize the impacts of RCAN1 on intestinal inflammation, inflammatory cytokines production, animal survival, and pathogen clearance following Salmonella challenge.

RESULTS

Histologic and quantitative assessments showed increased inflammation and elevated proinflammatory cytokines production in RCAN1-deficient mice. The aberrant inflammatory response was recapitulated in primary bone marrow-derived macrophages. In addition, we reveal a novel regulatory role for RCAN1 in the proinflammatory JNK signaling both in vitro and in vivo. Further analysis showed that the increased inflammation in RCAN1-deficient mice contributed to pathogen clearance and host survival.

CONCLUSIONS

The present study demonstrates that RCAN1 deficiency protects against Salmonella intestinal infection by enhancing proinflammatory JNK signaling.

Regulator of Calcineurin 1 in Periodontal Disease

Nuclear factor of activated T-cells (NFAT) and NF-kB pathway associated processes are involved in the pathogenesis of various inflammatory disorders, for example, periodontal disease. The activation of these pathways is controlled by the regulator of calcineurin 1 (RCAN1). The aim of this study was to elucidate the role of RCAN1 in periodontal disease. Healthy and inflamed periodontal tissues were analyzed by immunohistochemistry and immunofluorescence using specific rabbit polyclonal anti-RCAN1 antibodies. For expression analysis human umbilical vein endothelial cells (HUVEC) were used. HUVEC were incubated for 2 h with Vascular Endothelial Growth Factor (VEGF) or with wild type and laboratory strains of Porphyromonas gingivalis (P. gingivalis). Expression analysis of rcan1 and cox2 was done by real time PCR using specific primers for rcan1.4 and cox2. The expression of rcan1 was found to be significantly suppressed in endothelial cells of chronically inflamed periodontal tissues compared to healthy controls. Rcan1 and cox2 were significantly induced by VEGF and wild type and laboratory P. gingivalis strains. Interestingly, the magnitude of the rcan1 and cox2 induction was strain dependent. The results of this study indicate that RCAN1 is suppressed in endothelial cells of chronically inflamed periodontal tissues. During an acute infection, however, rcan1 seems to be upregulated in endothelial cells, indicating a modulating role in immune homeostasis of periodontal tissues.

The RCAN1 inhibits NF-κB and suppresses lymphoma growth in mice

Nuclear factor-κB (NF-κB) has a vital role in cell survival. Inhibition of NF-κB has been proven to be an efficient therapeutic pathway for various cancers. Activation of NF-κB is mainly through serine residues' phosphorylation of inhibitor of κBα (IκBα) by IKK complex. Phosphorylation at tyrosine 42 is an alternative pathway in regulation of IκBα and NF-κB signaling, though little is known about the underlying mechanism. Here we identified regulator of calcineurin 1 (RCAN1) as a novel endogenous inhibitor of NF-κB signaling pathway. RCAN1 can interact with IκBα and affect the phosphorylation of IκBα at tyrosine 42. Overexpression of RCAN1 by adenovirus reduced cell viability in lymphoma Raji cells and restrained the growth of lymphoma transplants in mice. We further found that N terminus 1–103aa of RCAN1 is sufficient to inhibit NF-κB and reduce cell viability of lymphoma cells. Our study implicated a novel therapeutic approach for lymphoma by RCAN1 through inhibition of NF-κB signaling.

Validation of microarray data in human lymphoblasts shows a role of the ubiquitin-proteasome system and NF-kB in the pathogenesis of Down syndrome

BACKGROUND

Down syndrome (DS) is a complex disorder caused by the trisomy of either the entire, or a critical region of chromosome 21 (21q22.1-22.3). Despite representing the most common cause of mental retardation, the molecular bases of the syndrome are still largely unknown.

METHODS

To better understand the pathogenesis of DS, we analyzed the genome-wide transcription profiles of lymphoblastoid cell lines (LCLs) from six DS and six euploid individuals and investigated differential gene expression and pathway deregulation associated with trisomy 21. Connectivity map and PASS-assisted exploration were used to identify compounds whose molecular signatures counteracted those of DS lymphoblasts and to predict their therapeutic potential. An experimental validation in DS LCLs and fetal fibroblasts was performed for the most deregulated GO categories, i.e. the ubiquitin mediated proteolysis and the NF-kB cascade.

RESULTS

We show, for the first time, that the level of protein ubiquitination is reduced in human DS cell lines and that proteasome activity is increased in both basal conditions and oxidative microenvironment. We also provide the first evidence that NF-kB transcription levels, a paradigm of gene expression control by ubiquitin-mediated degradation, is impaired in DS due to reduced IkB-alfa ubiquitination, increased NF-kB inhibitor (IkB-alfa) and reduced p65 nuclear fraction. Finally, the DSCR1/DYRK1A/NFAT genes were analysed. In human DS LCLs, we confirmed the presence of increased protein levels of DSCR1 and DYRK1A, and showed that the levels of the transcription factor NFATc2 were decreased in DS along with a reduction of its nuclear translocation upon induction of calcium fluxes.

CONCLUSIONS

The present work offers new perspectives to better understand the pathogenesis of DS and suggests a rationale for innovative approaches to treat some pathological conditions associated to DS.

RCAN1 is an important mediator of glucocorticoid-induced apoptosis in human leukemic cells

Glucocorticoid (GC) is a major therapeutic agent for the treatment of leukemia because of its ability to induce apoptosis in lymphoid cells. The mechanism causing apoptosis, however, is still controversial. Since the glucocorticoid receptor is a transcription factor, some of its target genes are expected to be implicated in apoptosis. In this study, using a GC-sensitive human pre-B leukemia cell line, Nalm-6, the FK506 binding protein 51 (FKBP5) and regulator of calcineurin 1 (RCAN1) genes were disrupted by homologous recombination, since the expression of both is up-regulated by GC in GC-sensitive but not in GC-resistant leukemic cell lines. While the disruption of FKBP5 had a marginal effect on GC-induced apoptosis, that of RCAN1 resulted in marked resistance to GC. In addition, overexpression of RCAN1 rendered cells more sensitive to DEX. In RCAN1-disrupted cells, levels of some pro-apoptotic and anti-apoptotic Bcl-2 family proteins were decreased and increased, respectively. Finally, phosphorylation of cAMP-response element binding protein (CREB) and up-regulation of CREB target genes by GC were inhibited by RCAN1 disruption, and treatment with a cAMP-inducing agent, forskolin, restored the sensitivity to GC in RCAN1-disrupted Nalm-6 cells. These findings suggest that up-regulation of RCAN1 expression followed by activation of the CREB pathway is required in GC-induced apoptosis.

Over-expression of DSCR1 protects against post-ischemic neuronal injury

Background and Purpose

The Down syndrome candidate region 1 (DSCR1) gene is located on human chromosome 21 and its protein is over-expressed in brains of Down syndrome individuals. DSCR1 can modulate the activity of calcineurin, a phosphatase abundant in the brain, but its influence on stroke outcome is not clear. We compared stroke outcome in wildtype (WT) and transgenic (DSCR1-TG) mice which over-express isoform 1 of human DSCR1.

Methods

Transient cerebral ischemia was produced by occlusion of the middle cerebral artery for 0.5 h. After 23.5 h reperfusion, we assessed neurological impairment, brain infarct and edema volume, leukocyte infiltration and markers of inflammation. Intrinsic resistance to apoptosis following glucose deprivation was also assessed in primary cultures of WT and DSCR1-TG neurons.

Results

In contrast to WT, DSCR1-TG mice had an improved neurological deficit score, greater grip strength, attenuated infarct volume and brain swelling, and lacked hippocampal lesions after stroke. Expression of mouse DSCR1-1, but not DSCR1-4, mRNA and protein was increased by ischemia in both WT and DSCR1-TG. Brain calcineurin activity was increased to a similar degree after ischemia in each genotype. DSCR1-TG mice had fewer infiltrating neutrophils and activated microglia compared with WT, in association with an attenuated upregulation of several pro-inflammatory genes. Neurons from DSCR1-TG mice were more resistant than WT neurons to apoptotic cell death following 24 h of glucose deprivation.

Conclusions

Over-expression of DSCR1 in mice improves outcome following stroke. Mechanisms underlying this protection may involve calcineurin-independent, anti-inflammatory and anti-apoptotic effects mediated by DSCR1 in neurons.

Over-expression of RCAN1 causes Down syndrome-like hippocampal deficits that alter learning and memory

People with Down syndrome (DS) exhibit abnormal brain structure. Alterations affecting neurotransmission and signalling pathways that govern brain function are also evident. A large number of genes are simultaneously expressed at abnormal levels in DS; therefore, it is a challenge to determine which gene(s) contribute to specific abnormalities, and then identify the key molecular pathways involved. We generated RCAN1-TG mice to study the consequences of RCAN1 over-expression and investigate the contribution of RCAN1 to the brain phenotype of DS. RCAN1-TG mice exhibit structural brain abnormalities in those areas affected in DS. The volume and number of neurons within the hippocampus is reduced and this correlates with a defect in adult neurogenesis. The density of dendritic spines on RCAN1-TG hippocampal pyramidal neurons is also reduced. Deficits in hippocampal-dependent learning and short- and long-term memory are accompanied by a failure to maintain long-term potentiation (LTP) in hippocampal slices. In response to LTP induction, we observed diminished calcium transients and decreased phosphorylation of CaMKII and ERK1/2-proteins that are essential for the maintenance of LTP and formation of memory. Our data strongly suggest that RCAN1 plays an important role in normal brain development and function and its up-regulation likely contributes to the neural deficits associated with DS.

Regulator of Calcineurin 1 Isoform 4 (RCAN1.4) Is Overexpressed in the Glomeruli of Diabetic Mice

Calcineurin (CaN) is activated in diabetes and plays a role in glomerular hypertrophy and extracellular matrix (ECM) accumulation. Here, kidneys from diabetic model mice were investigated for the expression of the regulator of CaN 1 (RCAN1) isoform 4 (RCAN1.4) which had been shown to be transcriptionally upregulated by CaN activation. We found the increased immunoreactivity for RCAN1 in the glomerular cells of db/db mice and streptozotocin-induced diabetic mice. In concordance, the expression of RCAN1 protein and RCAN1.4 mRNA were elevated in the whole kidney sample from db/db mice. Interleukin-1β (IL-1β), tumor necrosis factor-α, and glycated albumin (AGE-BSA) were identified as inducers of RCAN1.4 in mesangial cells. Pretreatment of cyclosporine A blocked the increases of RCAN1.4 stimulated by IL-1β or AGE-BSA, suggesting that activation of CaN is required for the RCAN1.4 induction. Stable transfection of RCAN1.4 in Mes-13 mesangial cells upregulated several factors relevant to ECM production and degradation. These results suggested that RCAN1.4 might act as a link between CaN activation and ECM turnover in diabetic nephropathy.

Inflammatory and Immunological parameters in adults with Down syndrome

Background

The increase in life expectancy within the general population has resulted in an increasing number of elderly adults, including patients with Down syndrome (DS), with a current life expectancy of about 50 years. We evaluate the parameters of humoral and cellular immune response, the quantitative expression of the regulator of calcineurin1 gene (RCAN1) and the production of cytokines. The study group consisted of adults DS (n = 24) and a control group with intellectual disability without Down syndrome (ID) (n = 21) and living in a similar environmental background. It was evaluated serology, immunophenotyping, the quantitative gene expression of RCAN1 and the production of cytokines.

Results

In the DS group, the results showed an increase in NK cells, CD8, decreased CD19 (p < 0.05) and an increase spontaneous production of IFNgamma, TNFalpha and IL-10 (p < 0.05). There was not any difference in RCAN1 gene expression between the groups.

Conclusions

These data suggest a similar humoral response in the two groups. The immunophenotyping suggests sign of premature aging of the immune system and the cytokine production show a proinflammatory profile.

Infections and immunodeficiency in Down syndrome

Down syndrome (DS) is the most common genetic disease and presents with cognitive impairment, cardiac and gastrointestinal abnormalities, in addition to other miscellaneous clinical conditions. DS individuals may have a high frequency of infections, usually of the upper respiratory tract, characterized by increased severity and prolonged course of disease, which are partially attributed to defects of the immune system. The abnormalities of the immune system associated with DS include: mild to moderate T and B cell lymphopenia, with marked decrease of naive lymphocytes, impaired mitogen-induced T cell proliferation, reduced specific antibody responses to immunizations and defects of neutrophil chemotaxis. Limited evidence of genetic abnormalities secondary to trisomy of chromosome 21 and affecting the immune system is available, such as the potential consequences of gene over-expression, most significantly SOD1 and RCAN1. Secondary immunodeficiency due to metabolic or nutritional factors in DS, particularly zinc deficiency, has been postulated. Non-immunological factors, including abnormal anatomical structures (e.g. small ear canal, tracheomalacia) and gastro-oesophageal reflux, may play a role in the increased frequency of respiratory tract infections. The molecular mechanisms leading to the immune defects observed in DS individuals and the contribution of these immunological abnormalities to the increased risk of infections require further investigation. Addressing immunological and non-immunological factors involved in the pathogenesis of infectious diseases may reduce the susceptibility to infections in DS subjects.

A-kinase-interacting protein 1 (AKIP1) acts as a molecular determinant of PKA in NF-kappaB signaling

The cAMP-dependent protein kinase (PKA) signaling pathway plays a crucial role in the pathogenesis of many NF-kappaB-related diseases. However, there have been controversial reports with regard to the PKA actions in the regulation of NF-kappaB activity. In this study, we have demonstrated the effect of PKA on NF-kappaB activity in view of AKIP1 action; and in 293 and HeLa cells, where the endogenous AKIP1 expression is minimal, PKA-activating agents inhibited the NF-kappaB-dependent reporter gene expression, blocked the interaction of PKAc and p65 subunit of NF-kappaB, and attenuated PKA-dependent phosphorylation of p65 on Ser-276. This inhibitory function of PKAc in NF-kappaB signaling was reversed by overexpression of AKIP1 in 293 cells. In the breast cancer cell line, MDA-MB231 cells and MCF7 cells, where the endogenous AKIP1 is abundant, the PKA signal was found to be synergized with NF-kappaB activation; PKA-activating agents enhanced NF-kappaB-dependent transcriptional activity and the interaction between p65 and PKAc and augmented the phosphorylation of p65 on Ser-276. After RNAi knockdown of AKIP1 in these breast cancer cells, we observed that PKA-activating agents antagonized NF-kappaB-dependent activation. Meanwhile, PKA inhibitor suppressed NF-kappaB-induced breast cancer cell proliferation and multiple NF-kappaB-dependent anti-apoptotic gene expression. It is likely that expression of AKIP1 determines the relationship between these two signal transduction pathways. These findings explained controversial results from various independent groups regarding the action of PKA signaling on the NF-kappaB activation cascade and suggested a possible therapeutic potential of PKA inhibitor in developing anti-cancer strategies.

A low-risk ZnT-8 allele (W325) for post-transplantation diabetes mellitus is protective against cyclosporin A-induced impairment of insulin secretion

SLC30A8 encodes the β-cell-specific zinc transporter-8 (ZnT-8) expressed in insulin secretory granules. The single-nucleotide polymorphism rs13266634 of SLC30A8 is associated with susceptibility to post-transplantation diabetes mellitus (PTDM). We tested the hypothesis that the polymorphic residue at position 325 of ZnT-8 determines the susceptibility to cyclosporin A (CsA) suppression of insulin secretion. INS (insulinoma)-1E cells expressing the W325 variant showed enhanced glucose-stimulated insulin secretion (GSIS) and were less sensitive to CsA suppression of GSIS. A reduced number of insulin granule fusion events accompanied the decrease in insulin secretion in CsA-treated cells expressing ZnT-8 R325; however, ZnT-8 W325-expressing cells exhibited resistance to the dampening of insulin granule fusion by CsA, and transported zinc ions into secretory vesicles more efficiently. Both tacrolimus and rapamycin caused similar suppression of GSIS in cells expressing ZnT-8 R325. However, cells expressing ZnT-8 W325 were resistant to tacrolimus, but not to rapamycin. The Down's syndrome candidate region-1 (DSCR1), an endogenous calcineurin inhibitor, overexpression and subsequent calcineurin inhibition significantly reduced GSIS in cells expressing the R325 but not the W325 variant, suggesting that differing susceptibility to CsA may be due to different interactions with calcineurin. These data suggest that the ZnT-8 W325 variant is protective against CsA-induced suppression of insulin secretion. Tolerance of ZnT-8 W325 to calcineurin activity may account for its protective effect in PTDM.

Two key genes closely implicated with the neuropathological characteristics in Down syndrome: DYRK1A and RCAN1

The most common genetic disorder Down syndrome (DS) displays various developmental defects including mental retardation, learning and memory deficit, the early onset of Alzheimer's disease (AD), congenital heart disease, and craniofacial abnormalities. Those characteristics result from the extra-genes located in the specific region called nDown syndrome critical region (DSCR)' in human chromosome 21. In this review, we summarized the recent findings of the DYRK1A and RCAN1 genes, which are located on DSCR and thought to be closely associated with the typical features of DS patients, and their implication to the pathogenesis of neural defects in DS. DYRK1A phosphorylates several transcriptional factors, such as CREB and NFAT, endocytic complex proteins, and AD-linked gene products. Meanwhile, RCAN1 is an endogenous inhibitor of calcineurin A, and its unbalanced activity is thought to cause major neuronal and/or non-neuronal malfunction in DS and AD. Interestingly, they both contribute to the learning and memory deficit, altered synaptic plasticity, impaired cell cycle regulation, and AD-like neuropathology in DS. By understanding their biochemical, functional and physiological roles, we hope to get important molecular basis of DS pathology, which would consequently lead to the basis to develop the possible therapeutic tools for the neural defects in DS. [BMB reports 2009; 42(1): 6-15].

Rcan1 negatively regulates Fc epsilonRI-mediated signaling and mast cell function

Aggregation of the high affinity IgE receptor (Fc epsilonRI) activates a cascade of signaling events leading to mast cell activation. Subsequently, inhibitory signals are engaged for turning off activating signals. We identified that regulator of calcineurin (Rcan) 1 serves as a negative regulator for turning off Fc epsilonRI-mediated mast cell activation. Fc epsilonRI-induced Rcan1 expression was identified by suppression subtractive hybridization and verified by real-time quantitative polymerase chain reaction and Western blotting. Deficiency of Rcan1 led to increased calcineurin activity, increased nuclear factor of activated T cells and nuclear factor kappaB activation, increased cytokine production, and enhanced immunoglobulin E-mediated late-phase cutaneous reactions. Forced expression of Rcan1 in wild-type or Rcan1-deficient mast cells reduced Fc epsilonRI-mediated cytokine production. Rcan1 deficiency also led to increased Fc epsilonRI-mediated mast cell degranulation and enhanced passive cutaneous anaphylaxis. Analysis of the Rcan1 promoter identified a functional Egr1 binding site. Biochemical and genetic evidence suggested that Egr1 controls Rcan1 expression. Our results identified Rcan1 as a novel inhibitory signal in Fc epsilonRI-induced mast cell activation and established a new link of Egr1 and Rcan1 in Fc epsilonRI signaling.

The high affinity peroxisome proliferator-activated receptor-gamma agonist RS5444 inhibits both initiation and progression of colon tumors in azoxymethane-treated mice

We evaluated RS5444, a thiazolidinedione high affinity PPARgamma agonist, for the ability to inhibit colon carcinogenesis in azoxymethane (AOM)-treated mice. In our initial experiment, mice were treated with RS5444 during AOM treatment, and the drug was withdrawn 12 weeks after the last injection of AOM. RS5444 significantly inhibited aberrant crypt focus formation under these circumstances. Furthermore, exposure to RS5444 during the course of AOM treatment effectively blocked colon tumor formation after withdrawal of the agonist. PPARgamma expression and nuclear localization were reduced in adenomas. RS5444 did not inhibit DNA synthesis in tumor cells, suggesting that PPARgamma activity was impaired in adenomas. To test this hypothesis, pre-existing adenomas were treated with RS5444 for 16 weeks. We observed a slight, albeit not statistically significant, reduction in tumor incidence in RS5444-treated mice. However, histological examination revealed that tumors from RS5444-treated mice were of significantly lower grade, as evaluated by the extent of dysplasia. Furthermore, carcinoma in situ was observed in about one-third of control tumors, but was never observed in RS5444-treated tumors. We conclude that RS5444 inhibits both initiation and progression of colon tumors in the AOM model of sporadic colon carcinogenesis.

Gene expression in periodontal tissues following treatment

BACKGROUND

In periodontitis, treatment aimed at controlling the periodontal biofilm infection results in a resolution of the clinical and histological signs of inflammation. Although the cell types found in periodontal tissues following treatment have been well described, information on gene expression is limited to few candidate genes. Therefore, the aim of the study was to determine the expression profiles of immune and inflammatory genes in periodontal tissues from sites with severe chronic periodontitis following periodontal therapy in order to identify genes involved in tissue homeostasis.Gingival biopsies from 12 patients with severe chronic periodontitis were taken six to eight weeks following non-surgical periodontal therapy, and from 11 healthy controls. As internal standard, RNA of an immortalized human keratinocyte line (HaCaT) was used. Total RNA was subjected to gene expression profiling using a commercially available microarray system focusing on inflammation-related genes. Post-hoc confirmation of selected genes was done by Realtime-PCR.

RESULTS

Out of the 136 genes analyzed, the 5% most strongly expressed genes compared to healthy controls were Interleukin-12A (IL-12A), Versican (CSPG-2), Matrixmetalloproteinase-1 (MMP-1), Down syndrome critical region protein-1 (DSCR-1), Macrophage inflammatory protein-2beta (Cxcl-3), Inhibitor of apoptosis protein-1 (BIRC-1), Cluster of differentiation antigen 38 (CD38), Regulator of G-protein signalling-1 (RGS-1), and Finkel-Biskis-Jinkins murine osteosarcoma virus oncogene (C-FOS); the 5% least strongly expressed genes were Receptor-interacting Serine/Threonine Kinase-2 (RIP-2), Complement component 3 (C3), Prostaglandin-endoperoxide synthase-2 (COX-2), Interleukin-8 (IL-8), Endothelin-1 (EDN-1), Plasminogen activator inhibitor type-2 (PAI-2), Matrix-metalloproteinase-14 (MMP-14), and Interferon regulating factor-7 (IRF-7).

CONCLUSION

Gene expression profiles found in periodontal tissues following therapy indicate activation of pathways that regulate tissue damage and repair.

Upregulation of DSCR1 (RCAN1 or Adapt78) in the peri-infarct cortex after experimental stroke

Down syndrome candidate region 1 (DSCR1; also known as RCAN1 or Adapt78) has been shown to be induced by calcium overload and oxidative stress which are included in the pathogenic hallmarks of the ischemic diseases. After ischemic stroke, inflammatory responses play an important role in the exacerbation of neuronal loss. In this study, we investigated the expression pattern of DSCR1 in the mouse cortex after transient middle cerebral artery occlusion (MCAO). Then, in vitro studies were taken to address whether inflammatory mediators could induce DSCR1. Male C57BL/6 mice were subjected to transient MCAO for 35 min and sacrificed at 6, 24, and 72 h after the reperfusion. The expression of DSCR1 began to increase in layer VI of the peri-infarct cortex at 24 h and was prominently enhanced at 72h after transient MCAO. Moreover, real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry showed that the induction of the DSCR1 isoform 4 (DSCR1-4) mRNA preceded the expression of the DSCR1 protein. In in vitro studies, tumor necrosis factor alpha and interleukin-1beta (IL-1beta) were found to induce strong upregulation of DSCR1-4 mRNA. Furthermore, western blot analysis revealed that overexpression of DSCR1-4 in SK-N-SH neuroblastoma cells attenuated IL-1beta-induced cyclooxygenase 2 and intercellular adhesion molecule 1 expression. These results demonstrate upregulation of DSCR1 in the mouse peri-infarct cortex following transient MCAO. In addition, our results suggest that inflammatory mediators such as TNFalpha and IL-1beta can induce DSCR1-4 transcription, which may be associated with the alleviation of inflammatory processes.

NF-kappaB-inducing kinase phosphorylates and blocks the degradation of Down syndrome candidate region 1

Down syndrome, the most frequent genetic disorder, is characterized by an extra copy of all or part of chromosome 21. Down syndrome candidate region 1 (DSCR1) gene, which is located on chromosome 21, is highly expressed in the brain of Down syndrome patients. Although its cellular function remains unknown, DSCR1 expression is linked to inflammation, angiogenesis, and cardiac development. To explore the functional role of DSCR1 and the regulation of its expression, we searched for novel DSCR1-interacting proteins using a yeast two-hybrid assay. Using a human fetal brain library, we found that DSCR1 interacts with NF-kappaB-inducing kinase (NIK). Furthermore, we demonstrate that NIK specifically interacts with and phosphorylates the C-terminal region of DSCR1 in immortalized hippocampal cells as well as in primary cortical neurons. This NIK-mediated phosphorylation of DSCR1 increases its protein stability and blocks its proteasomal degradation, the effects of which lead to an increase in soluble and insoluble DSCR1 levels. We show that an increase in insoluble DSCR1 levels results in the formation of cytosolic aggregates. Interestingly, we found that whereas the formation of these inclusions does not significantly alter the viability of neuronal cells, the overexpression of DSCR1 without the formation of aggregates is cytotoxic.

AKIP1 enhances NF-kappaB-dependent gene expression by promoting the nuclear retention and phosphorylation of p65

In this study, we have identified protein kinase A-interacting protein 1 (AKIP1) as a binding partner of NF-kappaB p65 subunit, and AKIP1 enhances the NF-kappaB-mediated gene expression. AKIP1 is a nuclear protein and known to interact with the catalytic subunit of PKA (PKAc). We identified AKIP1 by a yeast two-hybrid screen using the N terminus region of p65 as bait. The interaction between AKIP1 and p65 was confirmed by glutathione S-transferase pull-down assay in vitro and immunoprecipitation-Western blotting assay in vivo. We found that the PKAc was present in the AKIP1.p65 complex and enhanced the transcriptional activity of NF-kappaB by phosphorylating p65. In a transient luciferase assay, AKIP1 cotransfection efficiently increased the transcriptional activity of NF-kappaB induced by phorbol 12-myristate 13-acetate (PMA). When AKIP1 was knocked down by RNA interference, the PMA-mediated NF-kappaB-dependent gene expression was abolished, indicating a physiological role of AKIP1. We found that PKAc, which is maintained in an inactive form by binding to IkappaBalpha and NF-kappaB in resting cells, was activated by PMA-induced signaling and could phosphorylate p65. Overexpression of AKIP1 increased the PKAc binding to p65 and enhanced the PKAc-mediated phosphorylation of p65 at Ser-276. Interestingly, this p65 phosphorylation promoted nuclear translocation of p65 and enhanced NF-kappaB transcription. In fact, we observed that AKIP1 colocalized with p65 within the cells and appeared to retain p65 in nucleus. These findings indicate a positive role of AKIP1 in NF-kappaB signaling and suggest a novel mechanism by which AKIP1 augments the transcriptional competence of NF-kappaB.

Gene expression profiling of leukemic cells and primary thymocytes predicts a signature for apoptotic sensitivity to glucocorticoids

Background

Glucocorticoids (GC's) play an integral role in treatment strategies designed to combat various forms of hematological malignancies. GCs also are powerful inhibitors of the immune system, through regulation of appropriate cytokines and by causing apoptosis of immature thymocytes. By activating the glucocorticoid receptor (GR), GCs evoke apoptosis through transcriptional regulation of a complex, interactive gene network over a period of time preceding activation of the apoptotic enzymes. In this study we used microarray technology to determine whether several disparate types of hematologic cells, all sensitive to GC-evoked apoptosis, would identify a common set of regulated genes. We compared gene expression signatures after treatment with two potent synthetic GCs, dexamethasone (Dex) and cortivazol (CVZ) using a panel of hematologic cells. Pediatric CD4+/CD8+ T-cell leukemia was represented by 3 CEM clones: two sensitive, CEM-C7–14 and CEM-C1–6, and one resistant, CEM-C1–15, to Dex. CEM-C1–15 was also tested when rendered GC-sensitive by several treatments. GC-sensitive pediatric B-cell leukemia was represented by the SUP-B15 line and adult B-cell leukemia by RS4;11 cells. Kasumi-1 cells gave an example of the rare Dex-sensitive acute myeloblastic leukemia (AML). To test the generality of the correlations in malignant cell gene sets, we compared with GC effects on mouse non-transformed thymocytes.

Results

We identified a set of genes regulated by GCs in all GC-sensitive malignant cells. A portion of these were also regulated in the thymocytes. Because we knew that the highly Dex-resistant CEM-C1–15 cells could be killed by CVZ, we tested these cells with the latter steroid and again found that many of the same genes were now regulated as in the inherently GC-sensitive cells. The same result was obtained when we converted the Dex-resistant clone to Dex-sensitive by treatment with forskolin (FSK), to activate the adenyl cyclase/protein kinase A pathway (PKA).

Conclusion

Our results have identified small sets of genes that correlate with GC-sensitivity in cells from several hematologic malignancies. Some of these are also regulated in normal mouse thymocytes.

Differential expression of members of the RCAN family of calcineurin regulators suggests selective functions for these proteins in the brain

RCANs, also called Down Syndrome Critical Region-1 (DSCR1)-like proteins, Modulatory Calcineurin Interacting Proteins (MCIPs) or calcipressins, are regulators of calcineurin, a Ca(2+)-dependent protein phosphatase involved in several neuronal functions. Despite the potential importance of the RCAN proteins in brain physiology, very little is known about their relative abundance and distribution patterns in the central nervous system. In this study we report the expression and distribution of RCAN mRNA transcripts and proteins in the mouse brain. RT-PCR and Western blot analysis showed that all Rcan mRNAs (Rcan1-1, Rcan1-2, Rcan2-1, Rcan2-3 and Rcan3) and their corresponding protein products (RCAN1-L, RCAN1-S, RCAN2-L, RCAN2-S and RCAN3) are present in every adult mouse brain region examined. All protein isoforms are also expressed in these same brain regions at early postnatal stages. Within regions, RCAN1-L, RCAN1-S, RCAN2-L and RCAN3 are differentially expressed depending on the region and developmental stage, whereas RCAN2-S is distributed homogeneously. Detailed immunohistochemical analysis revealed significant differences in the cellular and subcellular distributions of RCAN proteins. In the adult, RCAN1 was mainly expressed in the neuropil throughout the brain. Although at lower levels, RCAN3 was also detected throughout the neuropil. In contrast, RCAN2 was highly expressed in scattered neurons, in both the nucleus and the cytoplasm. Interestingly, RCAN2 is the only member of the RCAN family that was detected in glial cells. Finally, the expression patterns of RCANs at early postnatal stages differed from those of the adult, in different brain areas, in both their distributions and relative abundance, suggesting that the expression of these proteins could be regulated during neuronal differentiation. The nonoverlapping expression patterns of the RCAN proteins shown here highlight the existence of different physiological scenarios and therefore suggest different RCAN functional activities in the brain, depending on the cellular context and developmental stage.