'Mutations in LAMB2 associate with albuminuria and Optic Nerve Hypoplasia with Hypopituitarism'

CONTEXT: Mutations in LAMB2, encoding the basement membrane protein, laminin β2, are associated with an autosomal recessive disorder characterized by congenital nephrotic syndrome, ocular abnormalities and neurodevelopmental delay (Pierson Syndrome). CASE DESCRIPTION: This report describes a twelve year old boy with short stature, visual impairment and developmental delay who presented with macroscopic haematuria and albuminuria. He had isolated growth hormone deficiency, optic nerve hypoplasia and a small anterior pituitary with corpus callosum dysgenesis on his cranial MRI, thereby supporting a diagnosis of optic nerve hypoplasia syndrome. Renal histopathology revealed focal segmental glomerulosclerosis. Using next generation sequencing on a targeted gene panel for steroid resistant nephrotic syndrome, compound heterozygous missense mutations were identified in LAMB2 [c.737G>A p.Arg246Gln, c.3982G>C p.Gly1328Arg]. Immunohistochemical analysis revealed reduced glomerular laminin β2 expression compared to control kidney and a thin basement membrane on electron microscopy. Laminin β2 is expressed during pituitary development and Lamb2-/- mice exhibit stunted growth, abnormal neural retinae and here, we show, abnormal parenchyma of the anterior pituitary gland. CONCLUSION: We propose that patients with genetically undefined optic nerve hypoplasia syndrome should be screened for albuminuria and if present, screened for mutations in LAMB2

Mutated CaV2.1 channels dysregulate CASK/P2X3 signaling in mouse trigeminal sensory neurons of R192Q Cacna1a knock-in mice

Background: ATP-gated P2X3 receptors of sensory ganglion neurons are important transducers of pain as they adapt their expression and function in response to acute and chronic nociceptive signals. The present study investigated the role of calcium/calmodulin-dependent serine protein kinase (CASK) in controlling P2X3 receptor expression and function in trigeminal ganglia from Cacna1a R192Q-mutated knock-in (KI) mice, a genetic model for familial hemiplegic migraine type-1.Results: KI ganglion neurons showed more abundant CASK/P2X3 receptor complex at membrane level, a result that likely originated from gain-of-function effects of R192Q-mutated CaV2.1 channels and downstream enhanced CaMKII activity. The selective CaV2.1 channel blocker \u3c9-Agatoxin IVA and the CaMKII inhibitor KN-93 were sufficient to return CASK/P2X3 co-expression to WT levels. After CASK silencing, P2X3 receptor expression was decreased in both WT and KI ganglia, supporting the role of CASK in P2X3 receptor stabilization. This process was functionally observed as reduced P2X3 receptor currents.Conclusions: We propose that, in trigeminal sensory neurons, the CASK/P2X3 complex has a dynamic nature depending on intracellular calcium and related signaling, that are enhanced in a transgenic mouse model of genetic hemiplegic migraine. \ua9 2013 Gnanasekaran et al.; licensee BioMed Central Ltd

The mechanism of functional up-regulation of P2X3 receptors of trigeminal sensory neurons in a genetic mouse model of Familial Hemiplegic Migraine type 1 (FHM-1)

A knock-in (KI) mouse model of FHM-1 expressing the R192Q missense mutation of the Cacna1a gene coding for the \u3b11 subunit of CaV2.1 channels shows, at the level of the trigeminal ganglion, selective functional up-regulation of ATP -gated P2X3 receptors of sensory neurons that convey nociceptive signals to the brainstem. Why P2X3 receptors are constitutively more responsive, however, remains unclear as their membrane expression and TRPV1 nociceptor activity are the same as in wildtype (WT) neurons. Using primary cultures of WT or KI trigeminal ganglia, we investigated whether soluble compounds that may contribute to initiating (or maintaining) migraine attacks, such as TNF\u3b1, CGRP, and BDNF, might be responsible for increasing P2X3 receptor responses. Exogenous application of TNF\u3b1 potentiated P2X3 receptor-mediated currents of WT but not of KI neurons, most of which expressed both the P2X3 receptor and the TNF\u3b1 receptor TNFR2. However, sustained TNF\u3b1 neutralization failed to change WT or KI P2X3 receptor currents. This suggests that endogenous TNF\u3b1 does not regulate P2X3 receptor responses. Nonetheless, on cultures made from both genotypes, exogenous TNF\u3b1 enhanced TRPV1 receptor-mediated currents expressed by a few neurons, suggesting transient amplification of TRPV1 nociceptor responses. CGRP increased P2X3 receptor currents only in WT cultures, although prolonged CGRP receptor antagonism or BDNF neutralization reduced KI currents to WT levels. Our data suggest that, in KI trigeminal ganglion cultures, constitutive up-regulation of P2X3 receptors probably is already maximal and is apparently contributed by basal CGRP and BDNF levels, thereby rendering these neurons more responsive to extracellular ATP. \ua9 2013 Hullugundi et al

In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization

Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers a realistic chance that this novel mechanism to inhibit afferent nerve sensitization may find its place in the sun and bring some merciful relief to the torment of persistent discomfort and pain. The development philosophy at Afferent is to conduct proof of concept patient studies and best identify target patient groups that may benefit from this new intervention

HDAC2 deregulation in tumorigenesis is causally connected to repression of immune modulation and defense escape.

Histone deacetylase 2 (HDAC2) is overexpressed or mutated in several disorders such as hematological cancers, and plays a critical role in transcriptional regulation, cell cycle progression and developmental processes. Here, we performed comparative transcriptome analyses in acute myeloid leukemia to investigate the biological implications of HDAC2 silencing versus its enzymatic inhibition using epigenetic-based drug(s). By gene expression analysis of HDAC2-silenced vs wild-type cells, we found that HDAC2 has a specific role in leukemogenesis. Gene expression profiling of U937 cell line with or without treatment of the well-known HDAC inhibitor vorinostat (SAHA) identifies and characterizes several gene clusters where inhibition of HDAC2 'mimics' its silencing, as well as those where HDAC2 is selectively and exclusively regulated by HDAC2 protein expression levels. These findings may represent an important tool for better understanding the mechanisms underpinning immune regulation, particularly in the study of major histocompatibility complex class II genes

THE USE OF FDG-PET IN THE INITIAL STAGING OF 142 PATIENTS WITH FOLLICULAR LYMPHOMA: A RETROSPECTIVE STUDY FROM THE FOLL05 RANDOMIZED TRIAL OF THE FONDAZIONE ITALIANA LINFOMI

BACKGROUND: The role of [\ub9\u2078F] fluorodeoxyglucose (FDG)-positron emission tomography (PET) in follicular lymphoma (FL) staging is not yet determined. PATIENTS AND METHODS: The aim of the present study was to investigate the role of PET in the initial staging of FL patients enrolled in the FOLL05-phase-III trial that compared first-line regimens (R-CVP, R-CHOP and R-FM). Patients should have undergone conventional staging and have available PET baseline to be included. RESULTS: A total of 142 patients were analysed. PET identified a higher number of nodal areas in 32% (46 of 142) of patients and more extranodal (EN) sites than computed tomography (CT) scan. Also, the Follicular Lymphoma International Prognostic Index (FLIPI) score increased in 18% (26 of 142) and decreased in 6% (9 of 142) of patients. Overall, the impact of PET on modifying the stage was highest in patients with limited stage. Actually, 62% (15 of 24) of cases with limited disease were upstaged with PET. CONCLUSIONS: The inclusion of PET among staging procedures makes the evaluation of patients with FL more accurate and has the potential to modify therapy decision and prognosis in a moderate proportion of patients. Further prospective clinical trials on FL should incorporate PET at different moments, and the therapeutic criteria to start therapy should be re-visited in the views of this new tool