Juvenile Huntington's Disease and Other PolyQ Diseases, Update on Neurodevelopmental Character and Comparative Bioinformatic Review of Transcriptomic and Proteomic Data

Polyglutamine (PolyQ) diseases are neurodegenerative disorders caused by the CAG repeat expansion mutation in affected genes resulting in toxic proteins containing a long chain of glutamines. There are nine PolyQ diseases: Huntington’s disease (HD), spinocerebellar ataxias (types 1, 2, 3, 6, 7, and 17), dentatorubral-pallidoluysian atrophy (DRPLA), and spinal bulbar muscular atrophy (SBMA). In general, longer CAG expansions and longer glutamine tracts lead to earlier disease presentations in PolyQ patients. Rarely, cases of extremely long expansions are identified for PolyQ diseases, and they consistently lead to juvenile or sometimes very severe infantile-onset polyQ syndromes. In apparent contrast to the very long CAG tracts, shorter CAGs and PolyQs in proteins seems to be the evolutionary factor enhancing human cognition. Therefore, polyQ tracts in proteins can be modifiers of brain development and disease drivers, which contribute neurodevelopmental phenotypes in juvenile- and adult-onset PolyQ diseases. Therefore we performed a bioinformatics review of published RNAseq polyQ expression data resulting from the presence of polyQ genes in search of neurodevelopmental expression patterns and comparison between diseases. The expression data were collected from cell types reflecting stages of development such as iPSC, neuronal stem cell, neurons, but also the adult patients and models for PolyQ disease. In addition, we extended our bioinformatic transcriptomic analysis by proteomics data. We identified a group of 13 commonly downregulated genes and proteins in HD mouse models. Our comparative bioinformatic review highlighted several (neuro)developmental pathways and genes identified within PolyQ diseases and mouse models responsible for neural growth, synaptogenesis, and synaptic plasticity.

Periostin Is Expressed by Pericytes and Is Crucial for Angiogenesis in Glioma

The expression of the matricellular protein periostin has been associated with glioma progression. In previous work we found an association of periostin with glioma angiogenesis. Here, we screen gliomas for POSTN expression and identify the cells that express periostin in human gliomas. In addition, we study the role of periostin in an in vitro model for angiogenesis. The expression of periostin was investigated by RT-PCR and by immunohistochemistry. In addition, we used double labeling and in situ RNA techniques to identify the expressing cells. To investigate the function of periostin, we silenced POSTN in a 3D in vitro angiogenesis model. Periostin expression was elevated in pilocytic astrocytoma and glioblastoma, but not in grade II/III astrocytomas and oligodendrogliomas. The expression of periostin colocalized with PDGFRβ+ cells, but not with OLIG2+/SOX2+ glioma stem cells. Silencing of periostin in pericytes in coculture experiments resulted in attenuation of the numbers and the length of the vessels formation and in a decrease in endothelial junction formation. We conclude that pericytes are the main source of periostin in human gliomas and that periostin plays an essential role in the growth and branching of blood vessels. Therefore, periostin should be explored as a novel target for developing anti-angiogenic therapy for glioma.

miR-378a influences vascularization in skeletal muscles

AIMS

MicroRNA-378a, highly expressed in skeletal muscles, was demonstrated to affect myoblasts differentiation and to promote tumour angiogenesis. We hypothesized that miR-378a could play a pro-angiogenic role in skeletal muscle and may be involved in regeneration after ischaemic injury in mice.

METHODS AND RESULTS

Silencing of miR-378a in murine C2C12 myoblasts did not affect differentiation but impaired their secretory angiogenic potential towards endothelial cells. miR-378a knockout (miR-378a-/-) in mice resulted in a decreased number of CD31-positive blood vessels and arterioles in gastrocnemius muscle. In addition, diminished endothelial sprouting from miR-378a-/- aortic rings was shown. Interestingly, although fibroblast growth factor 1 (Fgf1) expression was decreased in miR-378a-/- muscles, this growth factor did not mediate the angiogenic effects exerted by miR-378a. In vivo, miR-378a knockout did not affect the revascularization of the ischaemic muscles in both normo- and hyperglycaemic mice subjected to femoral artery ligation (FAL). No difference in regenerating muscle fibres was detected between miR-378a-/- and miR-378+/+ mice. miR-378a expression temporarily declined in ischaemic skeletal muscles of miR-378+/+ mice already on Day 3 after FAL. At the same time, in the plasma, the level of miR-378a-3p was enhanced. Similar elevation of miR-378a-3p was reported in the plasma of patients with intermittent claudication in comparison to healthy donors. Local adeno-associated viral vectors-based miR-378a overexpression was enough to improve the revascularization of the ischaemic limb of wild-type mice on Day 7 after FAL, what was not reported after systemic delivery of vectors. In addition, the number of infiltrating CD45+ cells and macrophages (CD45+ CD11b+ F4/80+ Ly6G-) was higher in the ischaemic muscles of miR-378a-/- mice, suggesting an anti-inflammatory action of miR-378a.

CONCLUSIONS

Data indicate miR-378a role in the pro-angiogenic effect of myoblasts and vascularization of skeletal muscle. After the ischaemic insult, the anti-angiogenic effect of miR-378a deficiency might be compensated by enhanced inflammation.

P11.12 Periostin is expressed by pericytes and is crucial for angiogenesis in glioma

BACKGROUND

The expression of the matricellular protein periostin has recently been associated with glioma progression and angiogenesis. The aim of the present study was to identify the cellular source of periostin expression in human gliomas and to study the role of periostin in an in vitro model for angiogenesis.

MATERIAL AND METHODS

The expression of periostin in various types and grades of brain tumors was investigated at the genetics level by RT-PCR and at the protein level by immunohistochemistry. In addition, the expression of periostin in glioma samples was studied by double labeling and in situ RNA techniques. Subsequently, by silencing periostin in a 3D in vitro angiogenesis model, its effects on angiogenesis were studied.

RESULTS

Periostin RNA and protein expression was found to be elevated in pilocytic astrocytoma and glioblastoma, but not in grade II/III astrocytomas. The expression of periostin co-localized with PDGFRβ + cells, but not with Olig2+ / Sox2+ glioma stem cells. Silencing of periostin in pericytes resulted in the attenuation of the number and the length of the vessels, and in decrease in the number of vessel junctions formed.

CONCLUSION

The results prove that pericytes are the main source of periostin in human gliomas. We demonstrate that periostin plays an essential role in the growth and branching of blood vessels. Therefore, periostin and / or its molecular interactions should be explored as a novel target for developing a new anti-angiogenic therapy for glioma.

Direct Inhibition of IRF-Dependent Transcriptional Regulatory Mechanisms Associated With Disease

Interferon regulatory factors (IRFs) are a family of homologous proteins that regulate the transcription of interferons (IFNs) and IFN-induced gene expression. As such they are important modulating proteins in the Toll-like receptor (TLR) and IFN signaling pathways, which are vital elements of the innate immune system. IRFs have a multi-domain structure, with the N-terminal part acting as a DNA binding domain (DBD) that recognizes a DNA-binding motif similar to the IFN-stimulated response element (ISRE). The C-terminal part contains the IRF-association domain (IAD), with which they can self-associate, bind to IRF family members or interact with other transcription factors. This complex formation is crucial for DNA binding and the commencing of target-gene expression. IRFs bind DNA and exert their activating potential as homo or heterodimers with other IRFs. Moreover, they can form complexes (e.g., with Signal transducers and activators of transcription, STATs) and collaborate with other co-acting transcription factors such as Nuclear factor-κB (NF-κB) and PU.1. In time, more of these IRF co-activating mechanisms have been discovered, which may play a key role in the pathogenesis of many diseases, such as acute and chronic inflammation, autoimmune diseases, and cancer. Detailed knowledge of IRFs structure and activating mechanisms predisposes IRFs as potential targets for inhibition in therapeutic strategies connected to numerous immune system-originated diseases. Until now only indirect IRF modulation has been studied in terms of antiviral response regulation and cancer treatment, using mainly antisense oligonucleotides and siRNA knockdown strategies. However, none of these approaches so far entered clinical trials. Moreover, no direct IRF-inhibitory strategies have been reported. In this review, we summarize current knowledge of the different IRF-mediated transcriptional regulatory mechanisms and how they reflect the diverse functions of IRFs in homeostasis and in TLR and IFN signaling. Moreover, we present IRFs as promising inhibitory targets and propose a novel direct IRF-modulating strategy employing a pipeline approach that combines comparative in silico docking to the IRF-DBD with in vitro validation of IRF inhibition. We hypothesize that our methodology will enable the efficient identification of IRF-specific and pan-IRF inhibitors that can be used for the treatment of IRF-dependent disorders and malignancies.

Limb ischemia and vessel regeneration: Is there a role for VEGF?

Vascular endothelial growth factor (VEGF), as an endothelial cell-specific mitogen, is crucial for new blood vessels formation. Atherosclerosis affecting the cardiovascular system causes ischemia and functio laesa in tissues supplied by the occluded vessels. When such a situation occurs in the lower extremities, it causes critical limb ischemia (CLI) often requiring leg amputation. Low oxygen tension leads to upregulation of hypoxia-regulated genes (i.e. VEGF), that should help to restore the impaired blood flow. In CLI these rescue mechanisms are, however, often inefficient. Moreover, there are many contradictory reports showing either induction, no changes or even down-regulation of VEGF in specimens taken from patients with CLI, as well as in samples collected from animals subjected to hindlimb ischemia. Additionally, taking into account numerous experimental and clinical data demonstrating rather insufficient therapeutic potential of VEGF, we called into question the role of this protein in limb ischemia and vessel regeneration. In this review we are also summarizing several aspects which can influence VEGF expression and its measurement in the ischemic tissues.

Heme Oxygenase-1 Controls an HDAC4-miR-206 Pathway of Oxidative Stress in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is an aggressive soft tissue cancer characterized by disturbed myogenic differentiation. Here we report a role for the oxidative stress response factor HO-1 in progression of RMS. We found that HO-1 was elevated and its effector target miR-206 decreased in RMS cell lines and clinical primary tumors of the more aggressive alveolar phenotype (aRMS). In embryonal RMS (eRMS), HO-1 expression was induced by Pax3/7-FoxO1, an aRMS hallmark oncogene, followed by a drop in miR-206 levels. Inhibition of HO-1 by tin protoporphyrin (SnPP) or siRNA downregulated Pax3/7-FoxO1 target genes and induced a myogenic program in RMS. These effects were not mediated by altered myoD expression; instead, cells with elevated HO-1 produced less reactive oxygen species, resulting in nuclear localization of HDAC4 and miR-206 repression. HO-1 inhibition by SnPP reduced growth and vascularization of RMS tumors in vivo accompanied by induction of miR-206. Effects of SnPP on miR-206 expression and RMS tumor growth were mimicked by pharmacologic inhibition of HDAC. Thus, HO-1 inhibition activates an miR-206-dependent myogenic program in RMS, offering a novel therapeutic strategy for treatment of this malignancy. Cancer Res; 76(19); 5707-18. ©2016 AACR.

The Role of miR-378a in Metabolism, Angiogenesis, and Muscle Biology

MicroRNA-378a (miR-378a, previously known as miR-378) is one of the small noncoding RNA molecules able to regulate gene expression at posttranscriptional level. Its two mature strands, miR-378a-3p and miR-378a-5p, originate from the first intron of the peroxisome proliferator-activated receptor gamma, coactivator 1 beta (ppargc1b) gene encoding PGC-1β. Embedding in the sequence of this transcriptional regulator of oxidative energy metabolism implies involvement of miR-378a in metabolic pathways, mitochondrial energy homeostasis, and related biological processes such as muscle development, differentiation, and regeneration. On the other hand, modulating the expression of proangiogenic factors such as vascular endothelial growth factor, angiopoietin-1, or interleukin-8, influencing inflammatory reaction, and affecting tumor suppressors, such as SuFu and Fus-1, miR-378a is considered as a part of an angiogenic network in tumors. In the latter, miR-378a can evoke broader actions by enhancing cell survival, reducing apoptosis, and promoting cell migration and invasion. This review describes the current knowledge on miR-378a linking oxidative/lipid metabolism, muscle biology, and blood vessel formation.

Prevalence and implications of TERT promoter mutation in uveal and conjunctival melanoma and in benign and premalignant conjunctival melanocytic lesions

PURPOSE

Hot-spot mutations in the promoter region of telomerase reverse transcriptase (TERT promoter mutations) occur frequently in cutaneous and conjunctival melanoma and are exceedingly rare in uveal melanoma. No information is available on the presence of these mutations in the conjunctival melanocytic precursor lesion primary acquired melanosis (PAM). We tested a cohort of uveal and conjunctival melanomas as well as conjunctival benign and premalignant melanocytic lesions for TERT promoter mutations in order to elucidate the role of these mutations in tumor progression.

METHODS

TERT promoter mutation analysis on fresh tumor DNA and DNA from formalin-fixed, paraffin-embedded specimens was performed by SNaPshot analysis in 102 uveal melanomas, 39 conjunctival melanomas, 26 PAM with atypia, 14 PAM without atypia, and 56 conjunctival nevi.

RESULTS

Mutations of the TERT promoter were not identified in conjunctival nevi or PAM without atypia, but were detected in 2/25 (8%) of PAM with atypia and 16/39 (41%) of conjunctival melanomas. A single TERT promoter mutation was detected in 102 uveal melanomas (1%).

CONCLUSIONS

We present the second documented case of TERT promoter mutation in uveal melanoma. In comparison with other types of melanoma, TERT promoter mutations occur at extremely low frequency in uveal melanoma. TERT promoter mutations are frequent in conjunctival melanoma and occur at lower frequency in PAM with atypia but were not detected in benign conjunctival melanocytic lesions. These findings favor a pathogenetic tumor progression role for TERT promoter mutations in conjunctival melanocytic lesions.

The role of NPY in metabolic homeostasis: implications for obesity therapy

Neuropeptide Y (NPY) is a 36 amino acid amidated peptide which has now emerged as an important regulator of feeding behaviour. Upon intracerebroventricular (icv.) administration, NPY produces a pronounced feeding response in a variety of species. The actions of NPY are believed to be mediated by a family of receptor subtypes named Y1 - y6. Recent studies suggest that the Y1 and Y5 receptor subtypes are intimately involved in NPY induced feeding. This review presents preclinical data obtained with receptor subtype selective agonists and antagonists as well as findings from knockout mice. These new data suggest that NPY receptor antagonists may become an additional option for treating human obesity.

Hammerhead ribozymes that selectively cleave the NPY Y1, Y4, and Y5 receptor full-length RNA

The concept of exploiting the ribozyme catalytic center for cleaving a specific target RNA transcript was applied to the design of selective ribozymes for the rat Y1, Y4, and Y5 receptor subtypes. Ribozymes selective for the neuropeptide Y (NPY) receptor subtypes were designed and chemically modified. Recognition sites were selected both according to the extent of their sequence homology between the receptor subtypes and according to the localization within single-stranded regions accessible for hybridization. Stability of the ribozymes against nucleolytic activities was increased by introducing 2'-O-methylribonucleosides and 3'-terminal modifications, such as inverted ends or dideoxynucleosides. Ribozymes cleaving the full-length rat Y1, Y4 (1200 nt), and Y5 receptor mRNA (2200 nt) were identified. The specificity of the recognition sites and the subtype selectivity of the ribozyme-mediated cleavage was demonstrated.