Evaluation of Antioxidant Defence Systems and Inflammatory Status in Basketball Elite Athletes

Intense physical activity can induce metabolic changes that modify specific biochemical biomarkers. In this scenario, the purpose of our study was to evaluate how intense physical activity can affect oxidative metabolism. Following this, fifteen professional basketball players and fifteen sedentary controls were recruited and subjected to two samplings of serum and urine in the pre-season (September) and two months after the start of the competitive season (November). Our results have shown an increase in athletes compared to controls in CK and LDH in September (respectively, p-value 0.003 and p-value < 0.001) and in November (both p-value < 0.001), whereas ALT is increased only in November (p-value 0.09). GGT serum levels were decreased in athletes compared to controls in both months (in September p-value 0.001 and in November p-value < 0.001). A gene expression analysis, carried out using RT-PCR, has revealed that IL-2, IL-6, IL-8, xCT and GCLM are increased in athletes in both months (p-value < 0.0001), while IL-10 and CHAC1 are increased only in September if compared to the controls (respectively, p-value 0.040 and p-value < 0.001). In conclusion, physical activity creates an adaptation of the systems involved in oxidative metabolism but without causing damage to the liver or kidney. This information could be of help to sports doctors for the prevention of injuries and illnesses in professional athletes for the construction of the athlete's passport.

Dietary Polyphenols, Microbiome, and Multiple Sclerosis: From Molecular Anti-Inflammatory and Neuroprotective Mechanisms to Clinical Evidence

Multiple sclerosis (MS) is a multifactorial, immune-mediated disease caused by complex gene-environment interactions. Dietary factors modulating the inflammatory status through the control of the metabolic and inflammatory pathways and the composition of commensal gut microbiota, are among the main environmental factors involved in the pathogenesis of MS. There is no etiological therapy for MS and the drugs currently used, often accompanied by major side effects, are represented by immunomodulatory substances capable of modifying the course of the disease. For this reason, nowadays, more attention is paid to alternative therapies with natural substances with anti-inflammatory and antioxidant effects, as adjuvants of classical therapies. Among natural substances with beneficial effects on human health, polyphenols are assuming an increasing interest due to their powerful antioxidant, anti-inflammatory, and neuroprotective effects. Beneficial properties of polyphenols on the CNS are achieved through direct effects depending on their ability to cross the blood-brain barrier and indirect effects exerted in part via interaction with the microbiota. The aim of this review is to examine the literature about the molecular mechanism underlying the protective effects of polyphenols in MS achieved by experiments conducted in vitro and in animal models of the disease. Significant data have been accumulated for resveratrol, curcumin, luteolin, quercetin, and hydroxytyrosol, and therefore we will focus on the results obtained with these polyphenols. Clinical evidence for the use of polyphenols as adjuvant therapy in MS is restricted to a smaller number of substances, mainly curcumin and epigallocatechin gallate. In the last part of the review, a clinical trial studying the effects of these polyphenols in MS patients will also be revised.

Low Sulfur Amino Acid, High Polyunsaturated Fatty Acid Diet Inhibits Breast Cancer Growth

Cancer cells may acquire resistance to stress signals and reprogram metabolism to meet the energetic demands to support their high proliferation rate and avoid death. Hence, targeting nutrient dependencies of cancer cells has been suggested as a promising anti-cancer strategy. We explored the possibility of killing breast cancer (BC) cells by modifying nutrient availability. We used in vitro models of BC (MCF7 and MDA-MB-231) that were maintained with a low amount of sulfur amino acids (SAAs) and a high amount of oxidizable polyunsatured fatty acids (PUFAs). Treatment with anti-apoptotic, anti-ferroptotic and antioxidant drugs were used to determine the modality of cell death. We reproduced these conditions in vivo by feeding BC-bearing mice with a diet poor in proteins and SAAs and rich in PUFAs (LSAA/HPUFA). Western blot analysis, qPCR and histological analyses were used to assess the anti-cancer effects and the molecular pathways involved. We found that BC cells underwent oxidative damage to DNA and proteins and both apoptosis and ferroptosis were induced. Along with caspases-mediated PARP1 cleavage, we found a lowering of the GSH-GPX4 system and an increase of lipid peroxides. A LSAA/HPUFA diet reduced tumor mass and its vascularization and immune cell infiltration, and induced apoptosis and ferroptotic hallmarks. Furthermore, mitochondrial mass was found to be increased, and the buffering of mitochondrial reactive oxygen species limited GPX4 reduction and DNA damage. Our results suggest that administration of custom diets, targeting the dependency of cancer cells on certain nutrients, can represent a promising complementary option for anti-cancer therapy.

Vitamin D Status, Cardiovascular Risk Profile, and miRNA-21 Levels in Hypertensive Patients: Results of the HYPODD Study

The vitamin D and microRNA (miR) systems may play a role in the pathogenesis of cardiometabolic disorders, including hypertension. The HYPODD study was a double-blind placebo-controlled trial aiming to assess the effects of cholecalciferol treatment in patients with well-controlled hypertension and hypovitaminosis D (25OHD levels < 50 nmol/L). In addition to this clinical trial, we also evaluated the effects of cholecalciferol and calcitriol treatment on miR-21 expression in vivo and in vitro, respectively. Changes in the cardiovascular risk profiles were evaluated in HYPODD patients treated with cholecalciferol (C-cohort) or with placebo (P-cohort). The miR-21circulating levels were measured in four C-cohort patients and five P-cohort patients. In vitro, the miR-21 levels were measured in HEK-293 cells treated with calcitriol or with ethanol vehicle control. Cholecalciferol treatment increased 25OHD levels and reduced parathormone, total cholesterol, and low-density lipoprotein cholesterol levels in C-cohort patients, whereas no significant changes in these parameters were observed in P-cohort patients. The miR-21 circulating levels did not change in the C- or the P-cohort patients upon treatment. Calcitriol treatment did not affect miR-21 levels in HEK-293 cells. In conclusion, hypovitaminosis D correction ameliorated the cardiovascular risk profiles in hypertensive patients treated with cholecalciferol but did not influence the miR-21 expression.

Increased Prevalence of Nephrolithiasis and Hyperoxaluria in Paget Disease of Bone

CONTEXT

Nephrolithiasis (NL) and primary hyperparathyroidism (HPTH) are metabolic complications of Paget disease of bone (PDB), but recent data regarding their prevalence in PDB patients are lacking.

OBJECTIVES

Study 1: To compare the prevalence of primary HPTH and NL in 708 patients with PDB and in 1803 controls. Study 2: To evaluate the prevalence of NL-metabolic risk factors in 97 patients with PDB and NL, 219 PDB patients without NL, 364 NL patients without PDB, and 219 controls, all of them without HPTH.

DESIGN

Cross-sectional multicentric study.

SETTING

Italian referral centers for metabolic bone disorders.

PARTICIPANTS

Patients with PDB from the Associazione Italiana malati di osteodistrofia di Paget registry. Participants in the Olivetti Heart and the Siena Osteoporosis studies.

MAIN OUTCOME MEASURES

HPTH; NL; NL-metabolic risk factors.

RESULTS

Patients with PDB showed higher prevalence of primary HPTH and NL compared with controls (P < 0.01). The NL recurrence occurs more frequently in patients with polyostotic PDB. About one-half of patients with PDB but without NL showed 1 or more NL-related metabolic risk factors. The hyperoxaluria (HyperOx) prevalence was higher in patients with PDB and NL compared with patients with NL but without PDB and in patients with PDB without NL compared with controls (P = 0.01). Patients with PDB and HyperOx showed a longer lapse of time from the last aminobisphosphonate treatment.

CONCLUSIONS

NL and HPTH are frequent metabolic complication of PDB. The NL occurrence should be evaluated in patients with PDB, particularly in those with polyostotic disease and/or after aminobisphosphonate treatment to apply an adequate prevention strategy.

An Overview of the Ferroptosis Hallmarks in Friedreich's Ataxia

BACKGROUND

Friedreich's ataxia (FRDA) is a neurodegenerative disease characterized by early mortality due to hypertrophic cardiomyopathy. FRDA is caused by reduced levels of frataxin (FXN), a mitochondrial protein involved in the synthesis of iron-sulphur clusters, leading to iron accumulation at the mitochondrial level, uncontrolled production of reactive oxygen species and lipid peroxidation. These features are also common to ferroptosis, an iron-mediated type of cell death triggered by accumulation of lipoperoxides with distinct morphological and molecular characteristics with respect to other known cell deaths.

SCOPE OF REVIEW

Even though ferroptosis has been associated with various neurodegenerative diseases including FRDA, the mechanisms leading to disease onset/progression have not been demonstrated yet. We describe the molecular alterations occurring in FRDA that overlap with those characterizing ferroptosis.

MAJOR CONCLUSIONS

The study of ferroptotic pathways is necessary for the understanding of FRDA pathogenesis, and anti-ferroptotic drugs could be envisaged as therapeutic strategies to cure FRDA.

Metabolism Regulation and Redox State: Insight into the Role of Superoxide Dismutase 1

Energy metabolism and redox state are strictly linked; energy metabolism is a source of reactive oxygen species (ROS) that, in turn, regulate the flux of metabolic pathways. Moreover, to assure redox homeostasis, metabolic pathways and antioxidant systems are often coordinately regulated. Several findings show that superoxide dismutase 1 (SOD1) enzyme has effects that go beyond its superoxide dismutase activity and that its functions are not limited to the intracellular compartment. Indeed, SOD1 is secreted through unconventional secretory pathways, carries out paracrine functions and circulates in the blood bound to lipoproteins. Striking experimental evidence links SOD1 to the redox regulation of metabolism. Important clues are provided by the systemic effects on energy metabolism observed in mutant SOD1-mediated amyotrophic lateral sclerosis (ALS). The purpose of this review is to analyze in detail the involvement of SOD1 in redox regulation of metabolism, nutrient sensing, cholesterol metabolism and regulation of mitochondrial respiration. The scientific literature on the relationship between ALS, mutated SOD1 and metabolism will also be explored, in order to highlight the metabolic functions of SOD1 whose biological role still presents numerous unexplored aspects that deserve further investigation.

Low-protein/high-carbohydrate diet induces AMPK-dependent canonical and non-canonical thermogenesis in subcutaneous adipose tissue

Low-protein/high-carbohydrate (LPHC) diet has been suggested to promote metabolic health and longevity in adult humans and animal models. However, the complex molecular underpinnings of how LPHC diet leads to metabolic benefits remain elusive. Through a multi-layered approach, here we observed that LPHC diet promotes an energy-dissipating response consisting in the parallel recruitment of canonical and non-canonical (muscular) thermogenic systems in subcutaneous white adipose tissue (sWAT). In particular, we measured Ucp1 induction in association with up-regulation of actomyosin components and several Serca (Serca1, Serca2a, Serca2b) ATPases. In beige adipocytes, we observed that AMPK activation is responsible for transducing the amino acid lowering in an enhanced fat catabolism, which sustains both Ucp1-and Serca-dependent energy dissipation. Limiting AMPK activation counteracts the expression of brown fat and muscular genes, including Ucp1 and Serca, as well as mitochondrial oxidative genes. We observed that mitochondrial reactive oxygen species are the upstream molecules controlling AMPK-mediated metabolic rewiring in amino acid-restricted beige adipocytes. Our findings delineate a novel metabolic phenotype of responses to amino acid shortage, which recapitulates some of the benefits of cool temperature in sWAT. In conclusion, this highlights LPHC diet as a valuable and practicable strategy to prevent metabolic diseases through the enhancement of mitochondrial oxidative metabolism and the recruitment of different energy dissipating routes in beige adipocytes.

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LPHC diet promotes brown- and muscular-like features in sWAT.

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In vitro amino acid shortage mimics the effects of LPHC diet.

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AMPK controls canonical and non-canonical thermogenesis in sWAT.

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L-Cys replenishment limits the AMPK-mediated adaptive responses in sWAT.

The Role of microRNAs, Long Non-coding RNAs, and Circular RNAs in Cervical Cancer

Prolonged infection of uterine cervix epithelium with human papillomavirus (HPV) and constitutive expression of viral oncogenes have been recognized as the main cause of the complex molecular changes leading to transformation of cervical epithelial cells. Deregulated expression of microRNAs (miRNA), long non-coding RNAs (lncRNA), and circular RNAs (circRNA) is involved in the initiation and promotion processes of cervical cancer development. Expression profiling of small RNAs in cervical neoplasia revealed up-regulated “oncogenic” miRNAs, such as miR-10a, miR-21, miR-19, and miR-146a, and down regulated “tumor suppressive” miRNAs, including miR-29a, miR-372, miR-214, and miR-218, associated with cell growth, malignant transformation, cell migration, and invasion. Also several lncRNAs, comprising among others HOTAIR, MALAT1, GAS5, and MEG3, have shown to be associated with various pathogenic processes such as tumor progression, invasion as well as therapeutic resistance and emerged as new diagnostic and prognostic biomarkers in cervical cancer. Moreover, human genes encoded circular RNAs, such as has_circ-0018289, have shown to sponge specific miRNAs and to concur to the deregulation of target genes. Viral encoded circE7 has also demonstrated to overexpress E7 oncoprotein thus contributing to cell transformation. In this review, we summarize current literature on the complex interplay between miRNAs, lncRNAs, and circRNAs and their role in cervical neoplasia.

Frataxin deficiency induces lipid accumulation and affects thermogenesis in brown adipose tissue

Decreased expression of mitochondrial frataxin (FXN) causes Friedreich's ataxia (FRDA), a neurodegenerative disease with type 2 diabetes (T2D) as severe comorbidity. Brown adipose tissue (BAT) is a mitochondria-enriched and anti-diabetic tissue that turns excess energy into heat to maintain metabolic homeostasis. Here we report that the FXN knock-in/knock-out (KIKO) mouse shows hyperlipidemia, reduced energy expenditure and insulin sensitivity, and elevated plasma leptin, recapitulating T2D-like signatures. FXN deficiency leads to disrupted mitochondrial ultrastructure and oxygen consumption as well as lipid accumulation in BAT. Transcriptomic data highlights cold intolerance in association with iron-mediated cell death (ferroptosis). Impaired PKA-mediated lipolysis and expression of genes controlling mitochondrial metabolism, lipid catabolism and adipogenesis were observed in BAT of KIKO mice as well as in FXN-deficient T37i brown and primary adipocytes. Significant susceptibility to ferroptosis was observed in adipocyte precursors that showed increased lipid peroxidation and decreased glutathione peroxidase 4. Collectively our data point to BAT dysfunction in FRDA and suggest BAT as promising therapeutic target to overcome T2D in FRDA.

Vitamin D Status in Paget Disease of Bone and Efficacy-Safety Profile of Cholecalciferol Treatment in Pagetic Patients with Hypovitaminosis D

Adequate vitamin D status is essential for skeletal health. Paget's disease of bone (PDB) is a common metabolic skeletal disorder, but data regarding the vitamin D status in PDB patients are lacking. We performed a case-control study to estimate vitamin D status in 708 PDB patients and in 1803 healthy controls from Italy and an observational prospective study to evaluate the efficacy-safety profile of oral cholecalciferol treatment [400.000 International Units (UI) of cholecalciferol administered in cycles of 8 weeks until 25OHD levels reaches 70 nmol/L as primary therapy and 50.000 UI of cholecalciferol administered every 2 weeks for 52 weeks for the maintenance therapy] in 82 PDB patients with hypovitaminosis D, i.e., 25OHD < 50 nmol/L. The main outcome measures for the prospective study were 25OHD levels, metabolic risk factors (RF) for nephrolithiasis, bone pain score (BPS), and pain medication score (PMS). Over half of PDB patients had hypovitaminosis D. Among PDB patients treated with cholecalciferol, 76 patients reached 25OHD levels ≥ 70 nmol/L after the first cycle of primary therapy and the remaining six patients after a second cycle. The maintenance therapy guaranteed 25OHD levels ≥ 70 nmol/L during the entire follow-up. The increase in 25OHD levels reduced PTH, BPS, and PMS levels, without changes in RF for nephrolithiasis. We can conclude that (i) hypovitaminosis D is frequent in PDB patients, (ii) cholecalciferol significantly increased 25OHD levels in PDB patients, and (iii) the correction of hypovitaminosis D improves the quality of life of PDB patients without inducing significant changes in RF for nephrolithiasis.

GKN1 expression in gastric cancer cells is negatively regulated by miR-544a

Gastrokine1 (GKN1), important for maintaining the physiological function of the gastric mucosa, is highly expressed in the stomach of healthy individuals but is down-regulated or absent in gastric tumor tissues and derived cell lines. The mechanisms underlying GKN1 gene inactivation are still unknown. We previously showed that GKN1 downregulation in gastric tumors is likely associated with an epigenetic transcriptional complex that negatively regulates GKN1 expression. In addition, TSA-mediated inhibition of HDACs leads to GKN1 restoration at the transcriptional level, but no at the translational level. These findings led to hypothesize the activation of a second regulatory mechanism microRNAs-mediated, thus resulting in translational repression and gene silencing. Bioinformatic analyses performed with 5 different algorithms highlighted that 4 miRNAs contained a seed sequence for the 3'UTR of GKN1 mRNA. Among these, only two miRNAs, hsa-miR-544a and miR-1245b-3p directly target the GKN1-3'UTR as evaluated by luciferase reporter assays. TaqMan miRNA assay performed on gastric cancer cell lines after TSA treatment showed a stronger increase of miR-544a expression than that of miR-1245b-3p. Finally, co-transfection of AGS cells with GKN1-3'UTR and premiR-544a showed compared to controls, a strong reduction of GKN1 expression both at translational and transcriptional levels. The up-regulation of miR-544a could be crucially involved in the GKN1 translational repression, thus suggesting its potential role as a biomarker and therapeutic target in GC patients. These findings indicate that epigenetic mechanisms leading to the inactivation of GKN1 play a key role in the multi-step process of gastric carcinogenesis and would provide an essential starting point for the development of new therapeutic strategies based on epigenetic targets for alternatives gene.

Adipocyte metabolism is improved by TNF receptor-targeting small RNAs identified from dried nuts

There is a growing interest in therapeutically targeting the inflammatory response that underlies age-related chronic diseases including obesity and type 2 diabetes. Through integrative small RNA sequencing, we show the presence of conserved plant miR159a and miR156c in dried nuts having high complementarity with the mammalian TNF receptor superfamily member 1a (Tnfrsf1a) transcript. We detected both miR159a and miR156c in exosome-like nut nanovesicles (NVs) and demonstrated that such NVs reduce Tnfrsf1a protein and dampen TNF-α signaling pathway in adipocytes. Synthetic single-stranded microRNAs (ss-miRs) modified with 2'-O-methyl group function as miR mimics. In plants, this modification naturally occurs on nearly all small RNAs. 2'-O-methylated ss-miR mimics for miR156c and miR159a decreased Tnfrsf1a protein and inflammatory markers in hypertrophic as well as TNF-α-treated adipocytes and macrophages. miR156c and miR159a mimics effectively suppress inflammation in mice, highlighting a potential role of plant miR-based, single-stranded oligonucleotides in treating inflammatory-associated metabolic diseases.

PERK-Mediated Unfolded Protein Response Activation and Oxidative Stress in PARK20 Fibroblasts

PARK20, an early onset autosomal recessive parkinsonism is due to mutations in the phosphatidylinositol-phosphatase Synaptojanin 1 (Synj1). We have recently shown that the early endosomal compartments are profoundly altered in PARK20 fibroblasts as well as the endosomal trafficking. Here, we report that PARK20 fibroblasts also display a drastic alteration of the architecture and function of the early secretory compartments. Our results show that the exit machinery from the Endoplasmic Reticulum (ER) and the ER-to-Golgi trafficking are markedly compromised in patient cells. As a consequence, PARK20 fibroblasts accumulate large amounts of cargo proteins within the ER, leading to the induction of ER stress. Interestingly, this stressful state is coupled to the activation of the PERK/eIF2α/ATF4/CHOP pathway of the Unfolded Protein Response (UPR). In addition, PARK20 fibroblasts reveal upregulation of oxidative stress markers and total ROS production with concomitant alteration of the morphology of the mitochondrial network. Interestingly, treatment of PARK20 cells with GSK2606414 (GSK), a specific inhibitor of PERK activity, restores the level of ROS, signaling a direct correlation between ER stress and the induction of oxidative stress in the PARK20 cells. All together, these findings suggest that dysfunction of early secretory pathway might contribute to the pathogenesis of the disease.

Nrf2 Pathway in Age-Related Neurological Disorders: Insights into MicroRNAs

A general hallmark of neurological diseases is the loss of redox homeostasis that triggers oxidative damages to biomolecules compromising neuronal function. Under physiological conditions the steady-state concentrations of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are finely regulated for proper cellular functions. Reduced surveillance of endogenous antioxidant defenses and/or increased ROS/RNS production leads to oxidative stress with consequent alteration of physiological processes. Neuronal cells are particularly susceptible to ROS/RNS due to their biochemical composition. Overwhelming evidences indicate that nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-linked pathways are involved in protective mechanisms against oxidative stress by regulating antioxidant and phase II detoxifying genes. As such, Nrf2 deregulation has been linked to both aging and pathogenesis of many human chronic diseases, including neurodegenerative ones such as Parkinson’s disease, Alzheimer’s disease and amyotrophic lateral sclerosis. Nrf2 activity is tightly regulated by a fine balance between positive and negative modulators. A better understanding of the regulatory mechanisms underlying Nrf2 activity could help to develop novel therapeutic interventions to prevent, slow down or possibly reverse various pathological states. To this end, microRNAs (miRs) are attractive candidates because they are linked to intracellular redox status being regulated and, post-transcriptionally, regulating key components of ROS/RNS pathways, including Nrf2.

microRNA-494 Favors HO-1 Expression in Neuroblastoma Cells Exposed to Oxidative Stress in a Bach1-Independent Way

Heme oxygenase 1 (HO-1) is crucially involved in cell adaptation to oxidative stress and has been demonstrated to play an important role in cancer progression and resistance to therapies. We recently highlighted that undifferentiated neuroblastoma (NB) cells are prone to counteract oxidative stress through the induction of HO-1. Conversely, differentiated NB cells were more sensitive to oxidative stress since HO-1 was scarcely upregulated. In this work, we investigated the role played by miR-494, which has been proved to be involved in cancer biology and in the modulation of oxidative stress, in the upregulation of HO-1. We showed that NB differentiation downregulates miR-494 level. In addition, endogenous miR-494 inhibition in undifferentiated cells impairs HO-1 induction in response to exposure to 500 µM H₂O₂, reducing the number of viable cells. The analysis of Bach1 expression did not reveal any significant modifications in any experimental conditions tested, proving that the impairment of HO-1 induction observed in cells treated with miR-494 inhibitor and exposed to H₂O₂ is independent from Bach1. Our results underline the role played by miR-494 in favoring HO-1 induction and cell adaptation to oxidative stress and contribute to the discovery of new potential pharmacological targets to improve anticancer therapies.

Role of uL3 in Multidrug Resistance in p53-Mutated Lung Cancer Cells

Cancer is one of the most common causes of death among adults. Chemotherapy is crucial in determining patient survival and quality of life. However, the development of multidrug resistance (MDR) continues to pose a significant challenge in the management of cancer. In this study, we analyzed the role of human ribosomal protein uL3 (formerly rpL3) in multidrug resistance. Our studies revealed that uL3 is a key determinant of multidrug resistance in p53-mutated lung cancer cells by controlling the cell redox status. We established and characterized a multidrug resistant Calu-6 cell line. We found that uL3 down-regulation correlates positively with multidrug resistance. Restoration of the uL3 protein level re-sensitized the resistant cells to the drug by regulating the reactive oxygen species (ROS) levels, glutathione content, glutamate release, and cystine uptake. Chromatin immunoprecipitation experiments and luciferase assays demonstrated that uL3 coordinated the expression of stress-response genes acting as transcriptional repressors of solute carrier family 7 member 11 (xCT) and glutathione S-transferase α1 (GST-α1), independently of Nuclear factor erythroid 2-related factor 2 (Nrf2). Altogether our results describe a new function of uL3 as a regulator of oxidative stress response genes and advance our understanding of the molecular mechanisms underlying multidrug resistance in cancers.

Comparative analysis of gene expression data reveals novel targets of senescence-associated microRNAs

In the last decades, cellular senescence is viewed as a complex mechanism involved in different processes, ranging from tumor suppression to induction of age-related degenerative alterations. Senescence-inducing stimuli are myriad and, recently, we and others have demonstrated the role exerted by microRNAs in the induction and maintenance of senescence, by the identification of a subset of Senescence-Associated microRNAs (SAmiRs) up-regulated during replicative or stress-induced senescence and able to induce a premature senescent phenotype when over-expressed in human primary cells. With the intent to find novel direct targets of two specific SAmiRs, SAmiR-494 and -486-5p, and cellular pathways which they are involved in, we performed a comparative analysis of gene expression profiles available in literature to select genes down-regulated upon replicative senescence of human primary fibroblasts. Among them, we searched for SAmiR's candidate targets by analyzing with different target prediction algorithms their 3'UTR for the presence of SAmiR-binding sites. The expression profiles of selected candidates have been validated on replicative and stress-induced senescence and the targeting of the 3'UTRs was assessed by luciferase assay. Results allowed us to identify Cell Division Cycle Associated 2 (CDCA2) and Inhibitor of DNA binding/differentiation type 4 (ID4) as novel targets of SAmiR-494 and SAmiR-486-5p, respectively. Furthermore, we demonstrated that the over-expression of CDCA2 in human primary fibroblasts was able to partially counteract etoposide-induced senescence by mitigating the activation of DNA Damage Response.

Identification of miR-494 direct targets involved in senescence of human diploid fibroblasts

Cellular senescence is a permanent cell cycle arrest triggered by different stimuli. We recently identified up-regulation of microRNA (miR)-494 as a component of the genetic program leading to senescence of human diploid IMR90 fibroblasts. Here, we used 2-dimensional differential gel electrophoresis (2D-DIGE) coupled to mass spectrometry to profile protein expression changes induced by adoptive overexpression of miR-494 in IMR90 cells. miR-494 induced robust perturbation of the IMR90 proteome by significantly (P≤0.05) down-regulating a number of proteins. Combination of mass spectrometry-based identification of down-regulated proteins and bioinformatic prediction of the miR-494 binding sites on the relevant mRNAs identified 26 potential targets of miR-494. Among them, computational analysis identified 7 potential evolution-conserved miR-494 targets. Functional miR-494 binding sites were confirmed in 3'-untranslated regions (UTRs) of 4 of them [heterogeneous nuclear ribonucleoprotein A3 (hnRNPA3), protein disulfide isomerase A3 (PDIA3), UV excision repair protein RAD23 homolog B (RAD23B), and synaptotagmin-binding cytoplasmic RNA-interacting protein (SYNCRIP)/heterogeneous nuclear ribonucleoprotein Q (hnRNPQ)]. Their reduced expression correlated with miR-494 up-regulation in senescent cells. RNA interference-mediated knockdown of hnRNPA3 and, to a lesser extent, RAD23B mirrored the senescent phenotype induced by miR-494 overexpression, blunting cell proliferation and causing up-regulation of SA-β-galactosidase and DNA damage. Ectopic expression of hnRNPA3 or RAD23B slowed the appearance of the senescent phenotype induced by miR-494. Overall, these findings identify novel miR-494 direct targets that are involved in cellular senescence.

A set of miRNAs participates in the cellular senescence program in human diploid fibroblasts

Here we show that replicative senescence in normal human diploid IMR90 fibroblasts is accompanied by altered expression of a set of microRNAs (miRNAs) (senescence-associated miRNAs), with 14 and 10 miRNAs being either up or downregulated (>2-fold), respectively, in senescent with respect to young cells. The expression of most of these miRNAs was also deregulated upon senescence induced by DNA damage (etoposide) or mild oxidative stress (diethylmaleate). Four downregulated miRNAs were part of miRNA family-17, recently associated to human cell and tissue aging. Moreover, eight upregulated and six downregulated miRNAs mapped in specific chromosomal clusters, suggesting common transcriptional regulation. Upon adoptive overexpression, seven upregulated miRNAs induced the formation of senescence-associated heterochromatin foci and senescence-associated β-galactosidase staining (P<0.05), which was accompanied, in the case of five of them, by reduced cell proliferation. Finally, miR-210, miR-376a(*), miR-486-5p, miR-494, and miR-542-5p induced double-strand DNA breaks and reactive oxygen species accumulation in transfected cells. In conclusion, we have identified a set of human miRNAs induced during replicative and chemically induced senescence that are able to foster the senescent phenotype by prompting DNA damage.

Physical and functional characterization of the genetic locus of IBtk, an inhibitor of Bruton's tyrosine kinase: evidence for three protein isoforms of IBtk

Bruton's tyrosine kinase (Btk) is required for B-cell development. Btk deficiency causes X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Btk lacks a negative regulatory domain and may rely on cytoplasmic proteins to regulate its activity. Consistently, we identified an inhibitor of Btk, IBtk, which binds to the PH domain of Btk and down-regulates the Btk kinase activity. IBtk is an evolutionary conserved protein encoded by a single genomic sequence at 6q14.1 cytogenetic location, a region of recurrent chromosomal aberrations in lymphoproliferative disorders; however, the physical and functional organization of IBTK is unknown. Here, we report that the human IBTK locus includes three distinct mRNAs arising from complete intron splicing, an additional polyadenylation signal and a second transcription start site that utilizes a specific ATG for protein translation. By northern blot, 5′RACE and 3′RACE we identified three IBTKα, IBTKβ and IBTKγ mRNAs, whose transcription is driven by two distinct promoter regions; the corresponding IBtk proteins were detected in human cells and mouse tissues by specific antibodies. These results provide the first characterization of the human IBTK locus and may assist in understanding the in vivo function of IBtk.

Cytokines, neurotrophins, and oxidative stress in brain disease from mucopolysaccharidosis IIIB

Mucopolysaccharidosis IIIB (MPS IIIB; Sanfilippo syndrome type B) is characterized by profound neurological deterioration. Because a murine model of MPS IIIB disease is available, we focused on analysis of gene expression in the brain and cerebellum of 7-month-old MPS IIIB mice by pathway-specific filter microarrays designed to probe apoptotic-related, neurotrophic signalling molecules and inflammatory cytokines and receptors. Moreover, we extended the analysis with real-time PCR performed at 1, 3, 7 months after birth. Bdnf was down-regulated in the brain but up-regulated in the cerebellum at 7 months of age, both at RNA and at protein levels. Cbln1 presented a threefold increase in the oldest brains while remaining unaltered in the cerebellum. Ccl3, Casp11, gp91(phox), p67(phox), and p47(phox) showed an increased expression in both brain and cerebellum at each examined time point. Ccl3, in particular, exhibited in both organs and at all times tested approximately a tenfold increase in its expression. Insofar as p47(phox), p67(phox), and gp91(phox) are all components of the phagocyte NADPH oxidase, our results suggest the possible involvement of the reactive oxygen species in the genesis of neurodegeneration in MPS IIIB disease.

p53 suppresses the Nrf2-dependent transcription of antioxidant response genes

Cells respond to the shift of intracellular environment toward pro-oxidant conditions by activating the transcription of numerous "antioxidant" genes. This response is based on the activation of the Nrf2 transcription factor, which transactivates the genes containing in their promoters the antioxidant response cis-elements (AREs). If the oxidative stress provokes DNA damage, a second response of the cell takes place, based on the activation of p53, which induces cell cycle arrest and/or apoptosis. Here we have explored the cross-talk between these two regulatory mechanisms. The results show that p53 counteracts the Nrf2-induced transcription of three ARE-containing promoters of the x-CT, NQO1, and GST-alpha1 genes. Endogenous transcripts of these antioxidant genes accumulate as a consequence of Nrf2 overexpression or exposure to electrophile diethylmaleate, but these effects are again blocked by p53 overexpression or endogenous p53 activation. Chromatin immunoprecipitation experiments support the hypothesis that this p53-dependent trans-repression is due to the direct interaction of p53 with the ARE-containing promoters. Considering that p53-induced apoptosis requires an accumulation of reactive oxygen species, this negative control on the Nrf2 transactivation appears to be aimed to prevent the generation of a strong anti-oxidant intracellular environment that could hinder the induction of apoptosis.

Detection and functional analysis of an SNP in the promoter of the human ferritin H gene that modulates the gene expression

The H ferritin promoter spans approximately 150 bp, upstream of the transcription start and is composed by two cis-elements in position -132 (A box) and -62 (B-box), respectively. The A box is recognized by the transcription factor Sp1, and the B-box by a protein complex called Bbf, which includes the CAAT binding factor NF-Y. In this study we performed a functional analysis of an H ferritin promoter allele carrying a G to T substitution adjacent to the Bbf binding site, in position -69. In vitro studies with reporter constructs revealed a significantly reduced transcriptional activity of this allele compared to that of the w.t. promoter that was mirrored by a decrease in Bbf binding. In vivo, this variant genotype is accompanied by a reduced amount of the H mRNA in peripheral blood lymphocytes.

Transcription regulation in NIH3T3 cell clones resistant to diethylmaleate-induced oxidative stress and apoptosis

To investigate the molecular mechanisms underlying the induction of cell resistance to oxidative stress, NIH3T3 cell clones (NIH-DEM clones) were isolated and selected for their ability to survive the exposure to diethylmaleate (DEM), a glutathione-depleting agent. The oxidative stress-resistant phenotype of these clones is stable for at least 1 month in the absence of DEM, and includes the resistance also to other apoptosis-inducing stimuli. The expression profile of several antioxidant genes was examined in four of the DEM-resistant clones in the presence and in absence of DEM. The response to the acute exposure to DEM is similar in wild type and DEM-resistant cells, with the exception of the glutathione-S-transferase alpha1 gene, whose expression is highly induced in NIH-DEM clones. However, in the absence of an acute stress, the expression of some genes is higher in DEM-resistant clones than in wild-type cells and the gene expression profile significantly varies among the clones. In particular, glutathione-S-transferase alpha1 and cystine/glutamate transporter mRNAs are increased in NIH-DEM-12. In these cells, the promoters of the two genes drive a stronger transcription than in wild-type cells, and this appears to be dependent on the transcription factor Nrf2.

Nitric oxide-induced endoplasmic reticulum stress activates the expression of cargo receptor proteins and alters the glycoprotein transport to the Golgi complex

The endoplasmic reticulum Golgi intermediate compartment 53 protein recycles continuously between the endoplasmic reticulum and the Golgi complex and ensures the anterograde transport of specific glycoproteins with the assistance of the Multiple Clotting Factor Deficiency adaptor protein. Therefore, to analyze the effect of the endoplasmic reticulum stress on the secretory pathway beyond the endoplasmic reticulum, we analyzed the expression of both proteins in J774 macrophages incubated with the nitric oxide donor DETA NONOate or with thapsigargin. Both proteins accumulated progressively, by a transcriptional mechanism, in response to these inducers. Nitric oxide also induced a higher level of calreticulin and glucose regulated 78 protein, two endoplasmic reticulum proteins controlled by the unfolded protein response. Interestingly, nitric oxide induced the processing of the activating transcription factor 6alpha of the unfolded protein response, while thapsigargin also induced the activation of the transcription factor X-box Binding Protein 1. In addition, we showed that the accumulation of both transporters occurred simultaneously with the activation of endoplasmic reticulum-stress-dependent apoptosis, suggesting that these proteins may participate in the events that will eventually decide the fate of the cell. Induction of endoplasmic reticulum stress affected the rate of anterograde transport of a reporter glycoprotein, indicating that the endoplasmic reticulum to Golgi transport is remarkably impaired. Our results indicate that increased levels of cargo receptor proteins might have a function either in the quality control of protein folding in the endoplasmic reticulum or in the homeostasis of the intermediate compartment and Golgi complex during cell stress.

Heat Shock Induces Preferential Translation of ERGIC-53 and Affects Its Recycling Pathway

ERGIC-53 is a lectin-like transport receptor protein, which recirculates between the ER and the Golgi complex and is required for the intracellular transport of a restricted number of glycoproteins. We show in this article that ERGIC-53 accumulates during the heat shock response. However, at variance with the unfolded protein response, which results in enhanced transcription of ERGIC-53 mRNA, heat shock leads only to enhanced translation of ERGIC-53 mRNA. In addition, the half-life of the protein does not change during heat shock. Therefore, distinct signal pathways of the cell stress response modulate the ERGIC-53 protein level. Heat shock also affects the recycling pathway of ERGIC-53. The protein rapidly redistributes in a more peripheral area of the cell, in a vesicular compartment that has a lighter sedimentation density on sucrose gradient in comparison to the compartment that contains the majority of ERGIC-53 at 37 degrees C. This effect is specific, as no apparent reorganization of the endoplasmic reticulum, intermediate compartment and Golgi complex is morphologically detectable in the cells exposed to heat shock. Moreover, the anterograde transport of two unrelated reporter proteins is not affected. Interestingly, MCFD2, which interacts with ERGIC-53 to form a complex required for the ER-to-Golgi transport of specific proteins, is regulated similarly to ERGIC-53 in response to cell stress. These results support the view that ERGIC-53 alone, or in association with MCFD2, plays important functions during cellular response to stress conditions.

Redox Control of Signal Transduction, Gene Expression and Cellular Senescence

Reactive oxygen species (ROS) act as subcellular messengers in such complex cellular processes as mitogenic signal transduction, gene expression, regulation of cell proliferation, replicative senescence, and apoptosis. They serve to maintain cellular homeostasis and their production is under strict control. However, the mechanisms whereby ROS act are still obscure. Here we review recent advances in our understanding of signaling mechanisms and recent data about the involvement of ROS in: (i) the regulation of the mitogenic transduction elements, particularly protein kinases and phosphatases; (ii) the regulation of gene expression; and (iii) the induction of replicative senescence and the role, if any, in aging and age-related disorders.

Fe65, a ligand of the Alzheimer's beta-amyloid precursor protein, blocks cell cycle progression by down-regulating thymidylate synthase expression

The functions of the Alzheimer's beta-amyloid precursor protein (APP) and of its complex with the adaptor protein Fe65 are still unknown. We have demonstrated that Fe65 is also a nuclear protein and APP functions as an extranuclear anchor, thus preventing Fe65 nuclear translocation. According to this finding, it was also demonstrated that Fe65 could play a role in the regulation of transcription. In the present paper we show that the overexpression of Fe65 prevents G(1) --> S cell cycle progression of serum-stimulated fibroblasts and that the contemporary overexpression of APP abolishes this effect of Fe65. The overexpression of Fe65 completely abolishes the activation of a key S phase gene, the thymidylate synthase (TS) gene, driven by the transcription factor LSF/CP2/LBP1 (LSF). This phenomenon is observed only in experimental conditions leading to the accumulation of Fe65 in the nucleus. Similarly, the two other members of the Fe65 protein family, Fe65L1 and Fe65L2, have been found to translocate into the nucleus and to prevent the activation of the TS gene promoter induced by LSF. Two results support the hypothesis that the inhibitory effect of Fe65 on cell cycle progression in fibroblasts is the result of the inhibition of TS gene expression: (i) Fe65 overexpression, but not Fe65 and APP co-expression, prevents the accumulation of endogenous TS upon the exposure of cells to serum, and (ii) thymidine addition to the culture medium completely overcomes the growth arrest caused by Fe65. In neuronal PC12 cells, the overexpression of Fe65 or of Fe65L1 and Fe65L2 blocks cell cycle, as observed in fibroblasts, but thymidine supplementation to culture medium does not revert this block, thus suggesting that Fe65 proteins induce in neuronal cells a gene expression program different from that activated in fibroblasts.

The beta-amyloid precursor protein functions as a cytosolic anchoring site that prevents Fe65 nuclear translocation

In this study we addressed the question of the intracellular localization of Fe65, an adaptor protein interacting with the beta-amyloid precursor protein (APP) and with the transcription factor CP2/LSF/LBP1. By using tagged Fe65 expression vectors, we observed that a significant fraction of Fe65 is localized in the nucleus of transfected COS7 cells. Furthermore, the isolation of nuclei from untransfected PC12 cells allowed us to observe that a part of the endogenous Fe65 is present in the nuclear extract. The analysis of Fe65 mutant constructs demonstrated that the region of the protein required for its nuclear translocation includes the WW domain, and that, on the other hand, a small fragment of 100 residues, including this WW domain, contains enough structural information to target a reporter protein (green fluorescent protein (GFP)-GFP) to the nucleus. To evaluate whether the Fe65-APP interaction could affect Fe65 intracellular trafficking, COS7 cells were cotransfected with APP(695) or APP(751) and with GFP-Fe65 expression vectors. These experiments demonstrated that Fe65 is no longer translocated to the nucleus when the cells overexpress APP, whereas the nuclear targeting of GFP-Fe65 mutants, unable to interact with APP, is unaffected by the coexpression of APP, thus suggesting that the interaction with APP anchors Fe65 in the cytosol.

Characterization of cis-acting elements in the promoter of the mouse metallothionein-3 gene. Activation of gene expression during neuronal differentiation of P19 embryonal carcinoma cells

The metallothionein (MT)3 gene is expressed predominantly in the brain and the organs of the reproductive system, and fails to respond to metal ions in vivo. A CTG repeat was proposed to function as a potential repressor element in nonpermissive cells, and a sequence similar to the JC virus silencer element was found to function as a negative element in permissive primary astrocytes. The objective of this study was to characterize further the mechanisms governing cell-type specific MT-3 gene transcription. We searched for a suitable cell line expressing the MT-3 gene to be used for determination of MT-3 promoter tissue specificity, and showed that MT-3 expression is activated during neuroectodermal differentiation of P19 cells induced by retinoic acid to levels similar to those found in whole brain. Deletion of the CTG repeat or of the JC virus silencer did not promote MT-3 promoter activity in nonpermissive cells, or enhance expression in permissive cells. We identified MT-3 promoter sequences interacting with liver and brain nuclear proteins, as assayed by DNase I footprinting analyses and electrophoretic mobility shift assay, and assessed the role of these sequences in the regulation of MT-3 expression by cotransfection experiments. We generated stable transfectants in permissive C6 and nonpermissive NIH-3T3 cells, and analysed the methylation status of the MT-3 gene. These studies show that regulation of tissue-specific MT-3 gene expression does not appear to involve a repressor, and suggest that other mechanisms such as chromatin organization and epigenetic modifications could account for the absence of MT-3 gene transcription in nonpermissive cells.

Fe65 and the protein network centered around the cytosolic domain of the Alzheimer's beta-amyloid precursor protein

A distinctive tract of all the forms of Alzheimer's disease is the extracellular deposition of a 40-42/43 amino acid-long peptide derived from the so-called beta-amyloid precursor protein (APP). This is a membrane protein of unknown function, whose short cytosolic domain has been recently demonstrated to interact with several proteins. One of these proteins, named Fe65, has the characteristics of an adaptor protein; in fact, it possesses three protein-protein interaction domains: a WW domain and two PID/PTB domains. The interaction with APP requires the most C-terminal PID/PTB domain, whereas the WW domain is responsible for the interaction with various proteins, one of which was demonstrated to be the mammalian homolog of the Drosophila enabled protein (Mena), which in turn interacts with the cytoskeleton. The second PID/PTB domain of Fe65 binds to the CP2/LSF/LBP1 protein, which is an already known transcription factor. The other proteins interacting with the cytosolic domain of APP are the G(o) heterotrimeric protein, APP-BP1 and X11. The latter interacts with APP through a PID/PTB domain and possesses two other protein-protein interaction domains. The small size of the APP cytodomain and the overlapping of its regions involved in the binding of Fe65 and X11 suggest the existence of competitive mechanisms regulating the binding of the various ligands to this cytosolic domain. In this short review the possible functional roles of this complex protein network and its involvement in the generation of Alzheimer's phenotype are discussed.

Fe65L2: a new member of the Fe65 protein family interacting with the intracellular domain of the Alzheimer's beta-amyloid precursor protein

We previously demonstrated that Fe65 protein is one of the ligands of the cytoplasmic domain of beta-amyloid precursor protein (APP). Another ligand of this molecule was recently identified; it is similar to Fe65, so it was named Fe65-like (Fe65L1). Herein we describe the cloning of another Fe65-like cDNA (Fe65L2), similar to Fe65 and to Fe65L1, which encodes a protein of approx. 50 kDa. Its cognate mRNA is expressed in various rat tissues, particularly in brain and testis. The three members of the Fe65 protein family share several structural and functional characteristics. The primary structures of the three proteins can be aligned in three regions corresponding to the protein-protein interaction domains of Fe65 [the protein-protein interaction domain containing two conserved tryptophan residues and the two phosphotyrosine interaction domain/phosphotyrosine binding (PID/PTB) domains], whereas the remaining sequences are poorly related. Like Fe65, Fe65L1 and Fe65L2 genes encode two different protein isoforms, derived from the alternative splicing of a very small exon of only six nucleotides, which results, within the N-terminal PID/PTB domain, in the presence or absence of two acidic/basic amino acids. Fe65L2 is able to interact, both in vitro and in vivo, with the intracellular domain of APP. Also, in the case of APP, another two closely related proteins exist, named beta-amyloid precursor-like protein (APLP)1 and APLP2: by using the interaction trap procedure we observed that both Fe65 and Fe65L2 interact with APP, APLP1 or APLP2, although with different efficiencies.

DNA-binding protein Pur alpha and transcription factor YY1 function as transcription activators of the neuron-specific FE65 gene promoter

Fe65 is an adaptor protein that interacts with the Alzheimer beta-amyloid precursor protein and is expressed mainly in the neurons of several regions of the nervous system. The FE65 gene has a TATA-less promoter that drives an efficient transcription in cells showing a neuronal phenotype, whereas its efficiency is poor in non-neuronal cells. A short sequence encompassing the transcription start site contains sufficient information to drive the transcription in neuronal cells but not in non-neural cells. Electrophoretic mobility-shift assays performed with rat brain nuclear extracts showed that three major DNA-protein complexes, named BI, BII and BIII, are formed by the FE65 minimal promoter. The proteins present in complexes BI and BII were purified from bovine brain; internal microsequencing of the purified proteins demonstrated that they corresponded to the previously isolated single-stranded-DNA-binding protein Pur alpha, abundantly expressed in the brain. In Chinese hamster ovary (CHO) cells, where the efficiency of FE65 promoter is very low, transient expression of Pur alpha increased the transcription efficiency of the FE65 minimal promoter. By using oligonucleotide competition and a specific antibody we demonstrated that the transcription factor YY1 is responsible for the formation of complex BIII. Also in this case, the transient expression of the YY1 cDNA in CHO cells resulted in an increased transcription from the FE65 minimal promoter. The absence of any co-operative effect when CHO cells were co-transfected with both YY1 and Pur alpha cDNA species suggests that two different transcription regulatory mechanisms could have a role in the regulation of the FE65 gene.

Interaction of the phosphotyrosine interaction/phosphotyrosine binding-related domains of Fe65 with wild-type and mutant Alzheimer's beta-amyloid precursor proteins

The two tandem phosphotyrosine interaction/phosphotyrosine binding (PID/PTB) domains of the Fe65 protein interact with the intracellular region of the Alzheimer's beta-amyloid precursor protein (APP). This interaction, previously demonstrated in vitro and in the yeast two hybrid system, also takes place in vivo in mammalian cells, as demonstrated here by anti-Fe65 co-immunoprecipitation experiments. This interaction differs from that occurring between other PID/PTB domain-containing proteins, such as Shc and insulin receptor substrate 1, and activated growth factor receptors as follows: (i) the Fe65-APP interaction is phosphorylation-independent; (ii) the region of the APP intracellular domain involved in the binding is larger than that of the growth factor receptor necessary for the formation of the complex with Shc; and (iii) despite a significant similarity the carboxyl-terminal regions of PID/PTB of Fe65 and of Shc are not functionally interchangeable in terms of binding cognate ligands. A role for Fe65 in the pathogenesis of familial Alzheimer's disease is suggested by the finding that mutant APP, responsible for some cases of familial Alzheimer's disease, shows an altered in vivo interaction with Fe65.

The DNA sequence encompassing the transcription start site of a TATA-less promoter contains enough information to drive neuron-specific transcription

The FE65 gene encodes a nuclear protein of unknown function that is expressed in several areas of the rat nervous system during development and in the adult animal, particularly in somatic and visceral ganglia. FE65 mRNA is abundant in neuronal cell lines, whereas it is barely detectable in non-neuronal cells. We identified the two transcription start sites of the FE65 gene and we isolated the rat genomic fragment containing one of these two transcriptional start sites. We demonstrate that this fragment contains a promoter able to direct an efficient transcription of a reporter gene in PC12 cells and in NTERA2 cells upon their differentiation with retinoic acid, whereas it functions poorly in non-neuronal cells, such as Rat2 fibroblasts and BRL hepatocytes. This promoter is composed of two regions. The first includes a cis-element whose removal greatly decreases the transcriptional efficiency in all cells examined and which forms similar complexes with proteins from PC12 and Rat2 cells. This cis-element binds Sp1 or another GC-binding factor. The second cis-element encompasses the transcription start site and is still able to direct transcription only in neuronal cells. The DNA-protein complexes formed by this cis-element in neuronal cells differ from those formed in non-neuronal cells. The analysis of point mutations in this region indicates that the proteins that bind to this cis-element interact with both overlapping and distinct nucleotide sequences.

Expression of the neuron-specific FE65 gene marks the development of embryo ganglionic derivatives

The major transcript of the FE65 gene is a neuron-specific mRNA that encodes a nuclear protein whose aminoterminal domain strongly activates the transcription of a reporter gene when fused to a heterologous DNA-binding domain. FE65 gene expression is regulated during neuronal differentiation of the NTERA-2 cell line, and it is temporally and spatially restricted during mouse embryo development. It is first detected around day 10 of gestation in the basal plate of the neural tube, and then, at the subsequent stages of development and in the newborn animals, it is found solely in neural structures. Its expression is most abundant in the neural crest derivatives (e.g. spinal and encephalic ganglia), ganglionic structures of sense organs (ganglionic layer of the retina and olfactory epithelium), as well as the ganglionic structures of the autonomic nervous system. Thus FE65 gene expression can be considered a marker of the development of embryo ganglionic derivatives.

Cellular retinoic-acid-binding-protein and retinol-binding-protein mRNA expression in the cells of the rat seminiferous tubules and their regulation by retinoids

The levels of the mRNA corresponding to the intracellular binding proteins for retinoic acid and retinol (CRABP1 and CRBP1, respectively) were studied in primary cultures of somatic and germ cells of the rat seminiferous tubules. We show that the CRABP1 mRNA is expressed in Sertoli and germ cells and a single molecular species of mRNA is detected. CRBP1 mRNA is detected in Sertoli and peritubular cells. The regulation of the expression of both genes by retinoids was studied in Sertoli cells. CRABP1 mRNA levels are not affected by either retinoic acid or retinol, whereas both compounds positively regulate CRBP1 mRNA synthesis in a dose-dependent manner. A fivefold increase in CRBP1 mRNA levels was observed 32-48 h after addition of either agent. These results demonstrate that in Sertoli cells the expression of CRABP1 is not affected by retinoids, similar to the situation observed in vivo and in other in-vitro cultures. CRBP1-gene expression is, instead, induced and the variations in CRBP1-mRNA levels may regulate the intracellular concentrations of retinoids, as a response to changes in the vitamin-A nutritional status.

Extinction of retinol-binding protein gene expression in somatic cell-hybrids: identification of the target sequences

The Retinol-Binding Protein (RBP) is expressed primarily in the liver. The regulatory elements involved in its tissue-specific expression have been identified and mapped to the 5' flanking region of the RBP gene. In this paper heterokaryons and somatic cell-hybrids have been produced and analysed in order to demonstrate that the RBP gene is subject to extinction and to identify the target sequences of this phenomenon. We show here that the gene is extinguished in fusions of hepatoma with a variety of cells of different species and embryonic lineages. The repression is not due to loss of the gene and occurs also when chromosome 10, where the gene is located, is inherited from the expressing parental cell-type. Hybrid clones were transfected with constructs carrying DNA segments of different lengths from the 5' flanking region of the RBP gene fused to a reporter gene. We demonstrate that extinction takes place also on an exogenous RBP-CAT gene, mimicking the phenomenon observed with the endogenous gene in its chromosomal location. Moreover, we identify and map the target sequences of the putative extinguishing function. Our data thus show that extinction of RBP is mediated through the DNA segment that is involved in its tissue-specific expression.

Expression of liver-specific genes coding for plasma proteins in protein deficiency

Protein deficiency leads to a decreased concentration of plasma proteins, although it is not clear whether this response is caused by alterations in gene transcription or in post-transcriptional events. The aim of this study was to investigate the expression of some liver-specific genes coding for plasma proteins in rats kept on a protein-free diet for 30 days. Cloned cDNA probes for the albumin, transthyretin, retinol-binding protein and prothrombin genes were used in Northern hybridizations to total liver RNA to compare their transcript levels in protein-deficient and control animals. Liver polysomes were also isolated and fractionated from the two groups of animals to examine the possible effects of protein deficiency on translation of the mRNAs. The results indicate that the albumin and transthyretin mRNAs are present in lower amounts in protein deficiency. The distribution profile along sucrose gradients shows that all mRNAs are undergoing translation, but in protein-deficient animals a small but consistent fraction of each mRNA is also present in the non-polysomal, low molecular weight fractions.

Regional mapping of RBP4 to 10q23----q24 and RBP1 to 3q21----q22 in man

The human gene coding for RBP4 has been assigned to 10q23----24 using a panel of somatic cell hybrids and in situ hybridization experiments. The mapping of the human RBP1, previously assigned by our group to chromosome 3 using a panel of somatic cell hybrids, was restricted to the region 3q21----22 using in situ experiments and Southern blots of genomic DNA from a hybrid retaining a portion of chromosome 3.

Detection of cellular retinol-binding protein messenger RNA in the somatic cells of the rat seminiferous tubules

A cDNA clone coding for Cellular Retinol-Binding Protein (CRBP) was used as a probe to study the expression of the gene in the somatic cells of the seminiferous tubules (Sertoli and peritubular cells). In this paper we demonstrate that these cells are actively involved in the synthesis of the specific mRNA. In Sertoli cells the gene is modulated by the hormones effective in spermatogenesis, such as FSH and testosterone. Moreover, peritubular cells revealed an approximately two times higher concentration of CRBP steady-state mRNA levels when compared with Sertoli cells.

Taq I RFLP in the human cellular retinol-binding protein (CRBP) gene

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