by Speranza L, Chambery A, Di Domenico M, Crispino M, Severino V, Volpicelli F, Leopoldo M, Bellenchi GC, di Porzio U, Perrone-Capano C
Serotonergic neurotransmission is mediated by at least 14 subtypes of 5-HT receptors. Among these, the CNS serotonin receptor 7 (5-HTR7) is involved in diverse physiological processes. Here we show that treatment of murine striatal and cortical neuronal cultures with 5-HTR7 agonists (8-OH-DPAT and LP-211) significantly enhances neurite outgrowth. This effect is abolished by the selective 5-HTR7 antagonist SB-269970, by the ERK inhibitor U0126, by the cyclin-dependent kinase 5 (Cdk5) inhibitor roscovitine, as well as by cycloheximide, an inhibitor of protein synthesis. These data indicate that 5-HTR7 activation stimulates extensive neurite elongation in CNS primary cultures, subserved by ERK and Cdk5 activation, and de novo protein synthesis. Two-dimensional (2D) gel electrophoresis coupled to Western blot analyses reveals both qualitative and quantitative expression changes in selected cytoskeletal proteins, following treatment of striatal primary cultures with LP-211. In particular, the 34 kDa isoform of MAP1B is selectively expressed in stimulated cultures, consistent with a role of this protein in tubulin polymerization and neurite elongation. In summary, our results show that agonist-dependent activation of the endogenous 5-HTR7 in CNS neuronal primary cultures stimulates ERK- and Cdk5-dependent neurite outgrowth, sustained by modifications of cytoskeletal proteins. These data support the hypothesis that the 5-HTR7 might play a crucial role in shaping neuronal morphology and behaviorally relevant neuronal networks, paving the way to new approaches able to modulate CNS connectivity.
on FASEB journal : official publication of the Federation of American Societies for Experimental Biology
by Jansen M, Wang W, Greco D, Bellenchi GC, di Porzio U, Brown AJ, Ikonen E
The brain is the most cholesterol-enriched tissue in the body. During brain development, desmosterol, an immediate precursor of cholesterol, transiently accumulates up to 30% of total brain sterols. This massive desmosterol deposition appears to be present in all mammalian species reported so far, including humans, but how it is achieved is not well understood. Here, we propose that desmosterol accumulation in the developing brain may be primarily caused by post-transcriptional repression of 3β-hydroxysterol 24-reductase (DHCR24) by progesterone. Furthermore, distinct properties of desmosterol may serve to increase the membrane active pool of sterols in the brain: desmosterol cannot be hydroxylated to generate 24S-hydroxycholesterol, a brain derived secretory sterol, desmosterol has a reduced propensity to be esterified as compared to cholesterol, and desmosterol may activate LXR to stimulate astrocyte sterol secretion. This regulated accumulation of desmosterol by progesterone-induced suppression of DHCR24 may facilitate the rapid enrichment and distribution of membrane sterols in the developing brain.
on Nature communications
by Verginelli F, Perin A, Dali R, Fung KH, Lo R, Longatti P, Guiot MC, Del Maestro RF, Rossi S, di Porzio U, Stechishin O, Weiss S, Stifani S
Glioblastoma (GBM) is the most common and deadly malignant brain cancer, with a median survival of <2 years. GBM displays a cellular complexity that includes brain tumour-initiating cells (BTICs), which are considered as potential key targets for GBM therapies. Here we show that the transcription factors FOXG1 and Groucho/TLE are expressed in poorly differentiated astroglial cells in human GBM specimens and in primary cultures of GBM-derived BTICs, where they form a complex. FOXG1 knockdown in BTICs causes downregulation of neural stem/progenitor and proliferation markers, increased replicative senescence, upregulation of astroglial differentiation genes and decreased BTIC-initiated tumour growth after intracranial transplantation into host mice. These effects are phenocopied by Groucho/TLE knockdown or dominant inhibition of the FOXG1:Groucho/TLE complex. These results provide evidence that transcriptional programmes regulated by FOXG1 and Groucho/TLE are important for BTIC-initiated brain tumour growth, implicating FOXG1 and Groucho/TLE in GBM tumourigenesis.
on Journal of neurochemistry
by Bellenchi GC, Volpicelli F, Piscopo V, Perrone-Capano C, di Porzio U
Research on stem cells has developed as one of the most promising areas of neurobiology. In the beginning of the 1990s, neurogenesis in the adult brain was indisputably accepted, eliciting great research efforts. Neural stem cells in the adult mammalian brain are located in the 'neurogenic' areas of the subventricular and subgranular zones. Nevertheless, many reports indicate that they subsist in other regions of the adult brain. Adult neural stem cells have arisen considerable interest as these studies can be useful to develop new methods to replace damaged neurons and treat severe neurological diseases such as neurodegeneration, stroke or spinal cord lesions. In particular, a promising field is aimed at stimulating or trigger a self-repair system in the diseased brain driven by its own stem cell population. Here, we will revise the latest findings on the characterization of active and quiescent adult neural stem cells in the main regions of neurogenesis and the factors necessary to maintain their active and resting states, stimulate migration and homing in diseased areas, hoping to outline the emerging knowledge for the promotion of regeneration in the brain based on endogenous stem cells.
on PloS one
by Volpicelli F, De Gregorio R, Pulcrano S, Perrone-Capano C, di Porzio U, Bellenchi GC
Due to their correlation with major human neurological diseases, dopaminergic neurons are some of the most studied neuronal subtypes. Mesencephalic dopaminergic (mDA) differentiation requires the activation of a cascade of transcription factors, among which play a crucial role the nuclear receptor Nurr1 and the paired-like homeodomain 3, Pitx3. During development the expression of Nurr1 precedes that of Pitx3 and those of typical dopaminergic markers such as tyrosine hydroxylase (TH) and dopamine Transporter (DAT) that are directly regulated by Nurr1. Interestingly we have previously demonstrated that Nurr1 RNA silencing reduced Pitx3 transcripts, leading to the hypothesis that Nurr1 may control Pitx3 expression.Here we show that Nurr1 overexpression up-regulates that of Pitx3 in a dose-dependent manner by binding to a non-canonical NBRE consensus sequence, located at the 5' site of the gene. Interestingly, this sequence shows the same effect as the canonical one in promoting gene translation, and its deletion abolishes the ability of Nurr1 to sustain reporter gene expression. Moreover, we show that there is a direct interaction between Nurr1 and the Pitx3 gene promoter in dopaminergic cell cultures and midbrain embryonic tissue. Altogether, our results suggest that the regulation of Pitx3 by Nurr1 may be an essential event controlling the development and function of mDA neurons.
on Experimental cell research
by Caiazzo M, Colucci-D'Amato L, Volpicelli F, Speranza L, Petrone C, Pastore L, Stifani S, Ramirez F, Bellenchi GC, di Porzio U
Krüppel-like factor 7 (KLF7) belongs to the large family of KLF transcription factors, which comprises at least 17 members. Within this family, KLF7 is unique since its expression is strictly restricted within the nervous system during development. We have previously shown that KLF7 is required for neuronal morphogenesis and axon guidance in selected regions of the nervous system, including hippocampus, olfactory bulbs and cortex, as well as in neuronal cell cultures. In the present work, we have furthered our analysis of the role of KLF7 in central nervous system development. By gene expression analysis during brain embryogenesis, we found significant alterations in dopaminergic neurons in Klf7 null mice. In particular, the tyrosine hydroxylase (TH) and dopamine transporter (Dat) transcripts are strongly decreased in the olfactory bulbs and ventral midbrain at birth, compared to wild-type littermates. Interestingly, Klf7-mutant mice show a dramatic reduction of TH-positive neurons in the olfactory bulbs, but no change in GABAergic or midbrain dopaminergic neurons. These observations raise the possibility that a lack of a KLF family member affects dopaminergic neuron development.
on Experimental cell research
by Caiazzo M, Colucci-D'Amato L, Esposito MT, Parisi S, Stifani S, Ramirez F, di Porzio U
Previous gene targeting studies in mice have implicated the nuclear protein Krüppel-like factor 7 (KLF7) in nervous system development while cell culture assays have documented its involvement in cell cycle regulation. By employing short hairpin RNA (shRNA)-mediated gene silencing, here we demonstrate that murine Klf7 gene expression is required for in vitro differentiation of neuroectodermal and mesodermal cells. Specifically, we show a correlation of Klf7 silencing with down-regulation of the neuronal marker microtubule-associated protein 2 (Map2) and the nerve growth factor (NGF) tyrosine kinase receptor A (TrkA) using the PC12 neuronal cell line. Similarly, KLF7 inactivation in Klf7-null mice decreases the expression of the neurogenic marker brain lipid-binding protein/fatty acid-binding protein 7 (BLBP/FABP7) in neural stem cells (NSCs). We also report that Klf7 silencing is detrimental to neuronal and cardiomyocytic differentiation of embryonic stem cells (ESCs), in addition to altering the adipogenic and osteogenic potential of mouse embryonic fibroblasts (MEFs). Finally, our results suggest that genes that are key for self-renewal of undifferentiated ESCs repress Klf7 expression in ESCs. Together with previous findings, these results provide evidence that KLF7 has a broad spectrum of regulatory functions, which reflect the discrete cellular and molecular contexts in which this transcription factor operates.
on Genes, brain, and behavior
by Leo D, Adriani W, Cavaliere C, Cirillo G, Marco EM, Romano E, di Porzio U, Papa M, Perrone-Capano C, Laviola G
Methylphenidate (MPH) administration to adolescent rodents produces persistent region-specific changes in brain reward circuits and alterations of reward-based behavior. We show that these modifications include a marked increment of serotonin (5-hydroxy-tryptamine) receptor type 7 (Htr7) expression and synaptic contacts, mainly in the nucleus accumbens, and a reduction of basal behavioral impulsivity. We show that neural and behavioral consequences are functionally related: administration of a selective Htr7 antagonist fully counteracts the MPH-reduced impulsive behavior and enhances impulsivity when administered alone in naive rats. Agonist-induced activation of endogenous Htr7 significantly increases neurite length in striatal neuron primary cultures, thus suggesting plastic remodeling of neuronal morphology. The mixed Htr (1a/7) agonist, 8-OH-DPAT, reduces impulsive behavior in adolescent rats and in naive adults, whose impulsivity is enhanced by the Htr7 antagonist. In summary, behavioral pharmacology experiments show that Htr7 mediates self-control behavior, and brain primary cultures experiments indicate that this receptor may be involved in the underlying neural plasticity, through changes in neuronal cytoarchitecture.
on PloS one
by Greco D, Volpicelli F, Di Lieto A, Leo D, Perrone-Capano C, Auvinen P, di Porzio U
In the mammalian central nervous system (CNS) an important contingent of dopaminergic neurons are localized in the substantia nigra and in the ventral tegmental area of the ventral midbrain. They constitute an anatomically and functionally heterogeneous group of cells involved in a variety of regulatory mechanisms, from locomotion to emotional/motivational behavior. Midbrain dopaminergic neuron (mDA) primary cultures represent a useful tool to study molecular mechanisms involved in their development and maintenance. Considerable information has been gathered on the mDA neurons development and maturation in vivo, as well as on the molecular features of mDA primary cultures. Here we investigated in detail the gene expression differences between the tissue of origin and ventral midbrain primary cultures enriched in mDA neurons, using microarray technique. We integrated the results based on different re-annotations of the microarray probes. By using knowledge-based gene network techniques and promoter sequence analysis, we also uncovered mechanisms that might regulate the expression of CNS genes involved in the definition of the identity of specific cell types in the ventral midbrain. We integrate bioinformatics and functional genomics, together with developmental neurobiology. Moreover, we propose guidelines for the computational analysis of microarray gene expression data. Our findings help to clarify some molecular aspects of the development and differentiation of DA neurons within the midbrain.
on Molecular and cellular probes
by Greco D, Leo D, di Porzio U, Perrone Capano C, Auvinen P
Affymetrix GeneChip represents a very reliable and standardized technology for genome-wide gene expression screening. However, in experiments carried out on complex biological samples (e.g. brain tissues composed of several diverse cell types), significant noise can arise due to important transcripts being expressed in a relatively small number of cells. This noise results in many observations coming from unreliable hybridization reactions. Here we propose a method for pre-filtering Affymetrix data according to measures of hybridization reliability. We used our pre-filtering method on a microarray dataset obtained from the brains of rats chronically treated with a psychostimulant drug. Our pre-filter protocol facilitates selection of biologically relevant candidate genes, which could be validated by real-time PCR with a rate of 98%.