Increased secretion of growth hormone leads to gigantism in children and acromegaly in adults; the genetic causes of gigantism and acromegaly are poorly understood. We performed clinical and genetic studies of samples obtained from 43 patients with gigantism and then sequenced an implicated gene in samples from 248 patients with acromegaly. We observed microduplication on chromosome Xq26.3 in samples from 13 patients with gigantism; of these samples, 4 were obtained from members of two unrelated kindreds, and 9 were from patients with sporadic cases. All the patients had disease onset during early childhood. Of the patients with gigantism who did not carry an Xq26.3 microduplication, none presented before the age of 5 years. Genomic characterization of the Xq26.3 region suggests that the microduplications are generated during chromosome replication and that they contain four protein-coding genes. Only one of these genes, GPR101, which encodes a G-protein–coupled receptor, was overexpressed in patients' pituitary lesions. We identified a recurrent GPR101 mutation (p.E308D) in 11 of 248 patients with acromegaly, with the mutation found mostly in tumors. When the mutation was transfected into rat GH3 cells, it led to increased release of growth hormone and proliferation of growth hormone–producing cells. We describe a pediatric disorder (which we have termed X-linked acrogigantism [X-LAG]) that is caused by an Xq26.3 genomic duplication and is characterized by early-onset gigantism resulting from an excess of growth hormone. Duplication of GPR101 probably causes X-LAG. We also found a recurrent mutation in GPR101 in some adults with acromegaly. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.)
15 February 2018 in Journal of Neuroscience Research
Persistent neuroinflammation is now recognized as a chief pathological component of practically all neurodegenerative diseases. Neuroinflammation in the central nervous system (CNS), is accompanied with immune responses of glial cells. Glial cells respond to pathological stimuli through antigen presentation, and cytokine and chemokine signaling. Therefore, limiting CNS inflammation represents prospective therapeutic approach in diseases like Alzheimer’s, amyotrophic lateral sclerosis, Parkinson’s, ischemia, various psychiatric disorders and Multiple sclerosis (MS). As a complex disease, MS is characterized by neuroinflamation, demyelination and sequential axonal loss. Due to unknown etiology and the heterogeneous presentation of the disease, MS is hard to treat and the search for potential therapeutics is wide and meticulous. However, finding a proper antineuroinflammatory drug may bring an advance in selecting novel treatment regimens of ample of neurodegenerative diseases and neurological disorders. The present review gives the overview of the existing and potential therapies in MS, aimed to modulate neuroinflammation and ensure neuroprotection.
Microglial cells are resident immune cells of the central nervous system (CNS), recognized as key elements in the regulation of neural homeostasis and the response to injury and repair. As excessive activation of microglia may lead to neurodegeneration, therapeutic strategies targeting its inhibition were shown to improve treatment of most neurodegenerative diseases. Benfotiamine is a synthetic vitamin B1 (thiamine) derivate exerting potentially anti-inflammatory effects. Despite the encouraging results regarding benfotiamine potential to alleviate diabetic microangiopathy, neuropathy and other oxidative stress-induced pathological conditions, its activities and cellular mechanisms during microglial activation have yet to be elucidated. In the present study, the anti-inflammatory effects of benfotiamine were investigated in lipopolysaccharide (LPS)-stimulated murine BV-2 microglia. We determined that benfotiamine remodels activated microglia to acquire the shape that is characteristic of non-stimulated BV-2 cells. In addition, benfotiamine significantly decreased production of pro-inflammatory mediators such as inducible form of nitric oxide synthase (iNOS) and NO; cyclooxygenase-2 (COX-2), heat-shock protein 70 (Hsp70), tumor necrosis factor alpha α (TNF-α), interleukin-6 (IL-6), whereas it increased anti-inflammatory interleukin-10 (IL-10) production in LPS stimulated BV-2 microglia. Moreover, benfotiamine suppressed the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinases (JNK) and protein kinase B Akt/PKB. Treatment with specific inhibitors revealed that benfotiamine-mediated suppression of NO production was via JNK1/2 and Akt pathway, while the cytokine suppression includes ERK1/2, JNK1/2 and Akt pathways. Finally, the potentially protective effect is mediated by the suppression of translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in the nucleus. Therefore, benfotiamine may have therapeutic potential for neurodegenerative diseases by inhibiting inflammatory mediators and enhancing anti-inflammatory factor production in activated microglia.
Pannexins are a newly discovered three-member family of proteins expressed in the brain and peripheral tissues that belong to the superfamily of gap junction proteins. However, in mammals pannexins do not form gap junctions, and their expression and function in the pituitary gland have not been studied. Here we show that the rat pituitary gland expresses mRNA and protein transcripts of pannexins 1 and 2 but not pannexin 3. Pannexin 1 was more abundantly expressed in the anterior lobe, whereas pannexin 2 was more abundantly expressed in the intermediate and posterior pituitary. Pannexin 1 was identified in corticotrophs and a fraction of somatotrophs, the S100-positive pituicytes of the posterior pituitary and AtT-20 (mouse pituitary adrenocorticotropin-secreting cells) and rat immortalized pituitary cells secreting prolactin, whereas pannexin 2 was detected in the S100-positive folliculostellate cells of the anterior pituitary, melanotrophs of the intermediate lobe, and vasopressin-containing axons and nerve endings in the posterior lobe. Overexpression of pannexins 1 and 2 in AtT-20 pituitary cells enhanced the release of ATP in the extracellular medium, which was blocked by the gap junction inhibitor carbenoxolone. Basal ATP release in At-T20 cells was also suppressed by down-regulating the expression of endogenous pannexin 1 but not pannexin 2 with their short interfering RNAs. These results indicate that pannexins may provide a pathway for delivery of ATP, which is a native agonist for numerous P2X cationic channels and G protein-coupled P2Y receptors endogenously expressed in the pituitary gland.