Novel IgCAM, MDGA1, expressed in unique cortical area- and layer-specific patterns and transiently by distinct forebrain populations of Cajal-Retzius neurons

The laminar and area patterning of the mammalian neocortex are two organizing principles that define its functional architecture. Members of the immunoglobulin (Ig) superfamily of cell adhesion molecules influence neural development by regulating cell adhesion, migration, and process growth. Here we describe the dynamic expression of the unique Ig-containing cell adhesion molecule, MAM domain-containing glycosylphosphatidylinositol anchor 1 (MDGA1), during forebrain development in mice and compare it with other markers. We show that MDGA1 is a layer-specific marker and an area-specific marker, being expressed in layers 2/3 throughout the neocortex, but within the primary somatosensory area (S1), MDGA1 is also uniquely expressed in layers 4 and 6a. Comparisons with other markers, including cadherins, serotonin, cytochrome oxidase, ROR beta, and COUP-TF1, reveal unique features of patterned expression of MDGA1 within cortex and S1 barrels. Further, our findings indicate that at earlier stages of development, MDGA1 is expressed by Reelin- and Tbr1-positive Cajal-Retzius neurons that originate from multiple sources outside of neocortex and emigrate into it. At even earlier stages, MDGA1 is expressed by the earliest diencephalic and mesencephalic neurons, which appear to migrate from a MDGA1-positive domain of progenitors in the diencephalon and form a "preplate." These findings show that MDGA1 is a unique marker for studies of cortical lamination and area patterning and together with recent reports suggest that MDGA1 has critical functions in forebrain/midbrain development.     

Transforming growth factor beta1 modulates cell migration in rat cortex: effects of ethanol

Transforming growth factor (TGF) beta1 regulates cell migration of non-neural cells. Hence, two hypotheses were tested: (i) that TGFbeta1 affects cell migration and the expression of associated adhesion proteins in developing cortex; and (ii) that these effects are antagonized by ethanol. The effects of TGFbeta1 (2.5-40 ng/ml) and ethanol (400 mg/dl) on cell migration were examined in organotypic cultures from fetal rat brains. Migration was determined by tracing the movement of cells pulse-labeled with bromodeoxyuridine. Cell migration was altered by TGFbeta1 in a concentration-dependent manner: at low concentrations, cell migration was promoted whereas at high concentrations TGFbeta1 impeded migration. Ethanol treatment alone reduced the rate of migration. Interestingly, the rate of cell migration in slices treated with both TGFbeta1 and ethanol was the same as that in untreated cultures. The expression of cell adhesion proteins (nCAM, integrin alpha3, alphav and beta1) was differentially effected by TGFbeta1 and/or ethanol. TGFbeta1 increased the expression of these adhesion proteins in a progressive, concentration-dependent manner. Likewise, ethanol also increased adhesion protein expression, however, combined TGFbeta1 and ethanol treatment reduced expression. Collectively, the data show that TGFbeta1 alters cell migration in the developing cortex and that the TGFbeta1 system is a target of ethanol toxicity.     

Experience-induced changes of dendritic spine densities in the prefrontal and sensory cortex: correlation with developmental time windows

The present study provides evidence for the hypothesis that the extent and the direction of experience-induced synaptic changes in cortical areas correlates with time windows of neuronal as well as endocrine development. Repeated brief exposure to maternal separation prior to the stress hyporesponsive period (SHRP) of the hypothalamic-pituitary-adrenal (HPA) axis induced significantly reduced dendritic spine density (-16%) in layer II/III pyramidal neurons of the anterior cingulate cortex (ACd) of 21-day-old rats, whereas separation after termination of the SHRP resulted in increased spine densities (+16%) in this neuron type. In addition, rats of both groups displayed elevated basal plasma levels of corticosterone at this age. Separation during the SHRP (postnatal days 5-7) did not influence spine density in the ACd, and basal corticosterone levels remained unchanged. In contrast, pyramidal neurons in the somatosensory cortex (SSC) displayed significantly enhanced spine densities (up to 52% increase) independent from the time of separation. These results indicate that alterations in the synaptic balance in limbic and sensory cortical regions in response to early emotional experience are region-specific and related to the maturational stage of endocrine and neuronal systems.     

Transforming growth factor-beta(1) in the kidney and urine of patients with glomerular disease and proteinuria.

BACKGROUND: Transforming growth factor-beta(1) (TGF-beta(1)) is the major fibrogenic growth factor implicated in the pathogenesis of renal scarring. Proteinuria is a poor prognostic feature for various types of glomerular disease and its toxic action may be related to the activation of tubular epithelial cells towards increased production of cytokines and chemoattractant peptides. In this work we studied the site of synthesis and expression profile of TGF-beta(1) in the renal tissue of patients with heavy proteinuria and examined the relation of this expression with the urinary excretion of TGF-beta(1). METHODS: Twenty-five patients with heavy proteinuria (8.4+/-3.0 g/24 h) were included in the study. All patients underwent a diagnostic kidney biopsy and were commenced on immunosuppressive therapy with corticosteroids and cyclosporin. The sites of synthesis and expression profile of TGF-beta(1) mRNA and protein in the kidney were examined by in situ hybridization and immunohistochemistry. Urinary and plasma TGF-beta(1) levels were determined by ELISA before the initiation of treatment and 6 months later and compared with those of normal subjects and of patients with IgA nephropathy and normal urinary protein excretion. RESULTS: The site of synthesis and expression of TGF-beta(1) in the renal tissue of patients with heavy proteinuria was mainly localized within the cytoplasm of tubular epithelial cells. Interstitial expression was also present but glomerular TGF-beta(1) expression was found only in patients with mesangial proliferation. Urinary TGF-beta(1) excretion was significantly higher in nephrotic patients compared with normal subjects and with patients with IgA nephropathy and normal urinary protein excretion (783+/-280 vs 310+/-140 and 375+/-90 ng/24 h, respectively; P<0.01). In patients with remission of proteinuria after immunosuppressive therapy, urinary TGF-beta(1) excretion was significantly reduced (from 749+/-290 to 495+/-130 ng/24 h; P<0.01), while in patients with persistent nephrotic syndrome, it remained elevated. CONCLUSIONS: The localization of TGF-beta(1) mRNA and protein within tubular epithelial cells, along with its increased urinary excretion in patients with nephrotic syndrome, suggest the activation of these cells by filtered protein towards increased TGF-beta(1) production.     

D1 dopamine receptor regulation of the levels of the cell-cycle-controlling proteins, cyclin D, P27 and Raf-1, in cerebral cortical precursor cells is mediated through cAMP-independent pathways

Previously, we demonstrated that dopamine D1 receptor (D1R) agonists inhibit epidermal growth factor (EGF)-induced passage of mouse fetal cerebral cortical precursor cells from the G1 phase to the S phase of the cell cycle. Here, we report that this action of D1R agonists may involve regulation of cyclin D, and P27, which respectively promote and suppress the G1 to S transition. Furthermore, regulation of Raf-1, a component of the receptor tyrosine kinase mitogen-activated protein kinase pathway engaged in the mitogenic activity of EGF, may also be involved. Specifically, levels of cyclin D and Raf-1 decrease, whereas those of P27 first increase and then decrease in a dose-dependent fashion in response to the D1R agonist, SKF38393. This agonist also promotes Raf-1 phosphorylation on serine 338 residue, suggesting increased activation of this protein. Only the latter effect can be blocked by adenylyl cyclase (AC) and cAMP-dependent protein kinase A (PKA) inhibitors, and mimicked by agonists of the cAMP signaling pathway. Another D1R agonist, SKF83959, which stimulates phospholipase Cbeta (PLCbeta) but not AC, reduces levels of Raf-1 and cyclin D similar to SKF38393. However, we detected only down-regulation of P27 by this agonist. Additionally, the concentration-dependent patterns of both SKF38393- and SKF83959-induced alterations in the levels of P27 closely resemble the effects of these ligands on the levels of the D1R-PLCbeta-associated second-messenger cascades linker, calcyon. These findings suggest that D1R-induced suppression of the cell cycle progression in EGF-supported fetal cortical precursor cells represents a net effect of competing cell cycle promoting and inhibiting molecular changes, which involve cyclin D, P27 and Raf-1. The data also show that cAMP second messenger cascade is not engaged in the D1R-induced regulation of the levels of these three proteins. Such regulation probably involves PLCbeta-associated pathways.     

Specific changes in plasma concentrations of matrix metalloproteinase-2 and -9, TIMP-1 and TGF-beta1 in patients with distinct types of primary glomerulonephritis.

BACKGROUND: Dysregulated renal expression of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMP) and TGF-beta1 contribute to the development of tubulo-interstitial fibrosis characteristic of progressive forms of primary glomerulonephritis (GN). There is little information on the circulating levels of these proteins in human GNs. Here, we assessed whether different histopathological GN types could be associated with distinct plasma patterns of MMPs and regulatory proteins. METHODS: Protein levels of MMP-2, MMP-9, TGF-beta1 and TIMP-1 were measured by ELISA in plasma from venous blood of 108 untreated patients with various types of primary GN defined by kidney biopsy, namely IgAN (n=63), membranous GN (MN, n=26), minimal change nephrotic syndrome (MCNS, n=12) and focal and segmental glomerular sclerosis (FSGS, n=7), and were compared with levels in 50 healthy subjects. Plasma samples were assayed for gelatinolytic activity (zymography). RESULTS: Zymography detected the proforms of MMP-2 and MMP-9. Compared with controls, IgAN patients exhibited a significant, parallel decrease in plasma levels of MMP-2, MMP-9 and TGF-beta1. In MN patients, decreased MMP-9 level contrasted with a high MMP-2 level and a normal TGF-beta1 level. In the MCNS/FSGS group, increased MMP-2 level contrasted with unchanged MMP-9 and decreased TGF-beta1 levels. Plasma concentration of TIMP-1 was elevated in all GN groups. There was no correlation between baseline MMP-2/MMP-9/TIMP-1/TGF-beta1 levels and the degree of renal dysfunction or with progression toward ESRD. CONCLUSIONS: Plasma concentrations of MMP-2, MMP-9 and TGF-beta1 significantly differed between the various histopathological types of primary GNs, thus suggesting the involvement of different underlying mechanisms in the regulation of glomerular and tubulointerstitial fibrosis in these renal diseases.     

生物钟基因BMAL1调控颌骨及全身骨发育的研究进展

脑和肌肉ARNT样蛋白1（brain and muscle arnt?like 1,BMAL1）基因作为昼夜生物钟的核心组成部分,在多种信号通路的介导下参与并调控体内各项生理活动。BMAL1基因的失活可以抑制软骨细胞和成骨细胞并促进破骨细胞的分化,阻碍软骨内成骨、膜内成骨及骨代谢,造成颌骨发育畸形、骨关节炎及骨质疏松等骨骼疾病。因此,笔者就BMAL1基因调控骨骼发育的研究进展作一综述,探讨其在颌骨及全身骨发育中可能发挥的作用及分子机制,以期为寻求新的防治方法提供思路。     

Co-expression and in vivo interaction of serotonin1A and serotonin2A receptors in pyramidal neurons of prefrontal cortex

The prefrontal cortex plays a key role in the control of higher brain functions and is involved in the pathophysiology and treatment of schizophrenia. Here we report that approximately 60% of the neurons in rat and mouse prefrontal cortex express 5-HT(1A) and/or 5-HT2A receptor mRNAs, which are highly co-localized (approximately 80%). The electrical stimulation of the dorsal and median raphe nuclei elicited 5-HT1A-mediated inhibitions and 5-HT2A-mediated excitations in identified pyramidal neurons recorded extracellularly in rat medial prefrontal cortex (mPFC). Opposite responses in the same pyramidal neuron could be evoked by stimulating the raphe nuclei at different coordinates, suggesting a precise connectivity between 5-HT neuronal subgroups and 5-HT1A and 5-HT2A receptors in pyramidal neurons. Microdialysis experiments showed that the increase in local 5-HT release evoked by the activation of 5-HT2A receptors in mPFC by DOI (5-HT2A/2C receptor agonist) was reversed by co-perfusion of 5-HT1A agonists. This inhibitory effect was antagonized by WAY-100635 and the prior inactivation of 5-HT1A receptors in rats and was absent in mice lacking 5-HT1A receptors. These observations help to clarify the interactions between the mPFC and the raphe nuclei, two key areas in psychiatric illnesses and improve our understanding of the action of atypical antipsychotics, acting through these 5-HT receptors.     

Evidence for abnormal regulation of circulating 1α,25-dihydroxyvitamin D in patients with pulmonary tuberculosis and normal calcium metabolism

Summary Available evidence indicates that hypercalcemia in pulmonary tuberculosis results from increases in circulating 1α,25-dihydroxyvitamin D [1α,25(OH)₂D]. To further characterize vitamin D metabolism in this disorder, the effects of vitamin D, 100,000 units a day for 4 days, were compared in 25 normal subjects and 11 patients with active pulmonary tuberculosis who were normocalcemic and had not had hypercalcemia. Serum calcium, phosphorus, 25-hydroxyvitamin D (25-OHD) and 1α,25(OH)₂D were measured. Whereas vitamin D increased mean serum 25-OHD from 20±2 (±SE) to 40±5 ng/ml (P<0.001) and did not change mean serum 1α,25(OH)₂D in the normals (33±2 vs. 31±2 pg/ml), it increased mean serum 25-OHD from 21±4 to 55±13 ng/ml (P<0.05) and mean serum 1α,25(OH)₂D from 28±2 to 35±3 pg/ml (P<0.05) in the patients. Serum calcium was normal and remained within the normal range in all subjects and patients. The findings indicate that there is a modest but significant abnormality in the regulation of circulating 1α,25(OH)₂D in normocalcemic patients with pulmonary tuberculosis. The results are similar to those previously reported by us in normocalcemic patients with sarcoidosis.