A haplotype spanning two genes, ELN and LIMK1, decreases their transcripts and confers susceptibility to intracranial aneurysms

Dorsal visual stream and LIMK1: hemideletion, haplotype, and enduring effects in children with Williams syndrome

BACKGROUND

Williams syndrome (WS), a rare neurodevelopmental disorder caused by hemizygous deletion of ~ 25 genes from chromosomal band 7q11.23, affords an exceptional opportunity to study associations between a well-delineated genetic abnormality and a well-characterized neurobehavioral profile. Clinically, WS is typified by increased social drive (often termed "hypersociability") and severe visuospatial construction deficits. Previous studies have linked visuospatial problems in WS with alterations in the dorsal visual processing stream. We investigated the impacts of hemideletion and haplotype variation of LIMK1, a gene hemideleted in WS and linked to neuronal maturation and migration, on the structure and function of the dorsal stream, specifically the intraparietal sulcus (IPS), a region known to be altered in adults with WS.

METHODS

We tested for IPS structural and functional changes using longitudinal MRI in a developing cohort of children with WS (76 visits from 33 participants, compared to 280 visits from 94 typically developing age- and sex-matched participants) over the age range of 5-22. We also performed MRI studies of 12 individuals with rare, shorter hemideletions at 7q11.23, all of which included LIMK1. Finally, we tested for effects of LIMK1 variation on IPS structure and imputed LIMK1 expression in two independent cohorts of healthy individuals from the general population.

RESULTS

IPS structural (p < 10-4 FDR corrected) and functional (p < .05 FDR corrected) anomalies previously reported in adults were confirmed in children with WS, and, consistent with an enduring genetic mechanism, were stable from early childhood into adulthood. In the short hemideletion cohort, IPS deficits similar to those in WS were found, although effect sizes were smaller than those found in WS for both structural and functional findings. Finally, in each of the two general population cohorts stratified by LIMK1 haplotype, IPS gray matter volume (pdiscovery < 0.05 SVC, preplication = 0.0015) and imputed LIMK1 expression (pdiscovery = 10-15, preplication = 10-23) varied according to LIMK1 haplotype.

CONCLUSIONS

This work offers insight into neurobiological and genetic mechanisms responsible for the WS phenotype and also more generally provides a striking example of the mechanisms by which genetic variation, acting by means of molecular effects on a neural intermediary, can influence human cognition and, in some cases, lead to neurocognitive disorders.

Whole-exome sequencing in a Japanese multiplex family identifies new susceptibility genes for intracranial aneurysms

Background

Intracranial aneurysms (IAs) cause subarachnoid hemorrhage, which has high rates of mortality and morbidity when ruptured. Recently, the role of rare variants in the genetic background of complex diseases has been increasingly recognized. The aim of this study was to identify rare variants for susceptibility to IA.

Methods

Whole-exome sequencing was performed on seven members of a Japanese pedigree with highly aggregated IA. Candidate genes harboring co-segregating rare variants with IA were re-sequenced and tested for association with IA using additional 500 probands and 323 non-IA controls. Functional analysis of rare variants detected in the pedigree was also conducted.

Results

We identified two gene variants shared among all four affected participants in the pedigree. One was the splicing donor c.1515+1G>A variant in NPNT (Nephronectin), which was confirmed to cause aberrant splicing by a minigene assay. The other was the missense p.P83T variant in CBY2 (Chibby family member 2). Overexpression of p.P83T CBY2 fused with red fluorescent protein tended to aggregate in the cytoplasm. Although Nephronectin has been previously reported to be involved in endothelial angiogenic functions, CBY2 is a novel molecule in terms of vascular pathophysiology. We confirmed that CBY2 was expressed in cerebrovascular smooth muscle cells in an isoform2-specific manner. Targeted CBY2 re-sequencing in additional case-control samples identified three deleterious rare variants (p.R46H, p.P83T, and p.L183R) in seven probands, showing a significant enrichment in the overall probands (8/501) compared to the controls (0/323) (p = 0.026, Fisher’s extract test).

Conclusions

NPNT and CBY2 were identified as novel susceptibility genes for IA. The highly heterogeneous and polygenic architecture of IA susceptibility can be uncovered by accumulating extensive analyses that focus on each pedigree with a high incidence of IA.

LIMK (LIM Kinase) Inhibition Prevents Vasoconstriction- and Hypertension-Induced Arterial Stiffening and Remodeling

Increased arterial stiffness and vascular remodeling precede and are consequences of hypertension. They also contribute to the development and progression of life-threatening cardiovascular diseases. Yet, there are currently no agents specifically aimed at preventing or treating arterial stiffening and remodeling. Previous research indicates that vascular smooth muscle actin polymerization participates in the initial stages of arterial stiffening and remodeling and that LIMK (LIM kinase) promotes F-actin formation and stabilization via cofilin phosphorylation and consequent inactivation. Herein, we hypothesize that LIMK inhibition is able to prevent vasoconstriction- and hypertension-associated arterial stiffening and inward remodeling. We found that small visceral arteries isolated from hypertensive subjects are stiffer and have greater cofilin phosphorylation than those from nonhypertensives. We also show that LIMK inhibition prevents arterial stiffening and inward remodeling in isolated human small visceral arteries exposed to prolonged vasoconstriction. Using cultured vascular smooth muscle cells, we determined that LIMK inhibition prevents vasoconstrictor agonists from increasing cofilin phosphorylation, F-actin volume, and cell cortex stiffness. We further show that localized LIMK inhibition prevents arteriolar inward remodeling in hypertensive mice. This indicates that hypertension is associated with increased vascular smooth muscle cofilin phosphorylation, cytoskeletal stress fiber formation, and heightened arterial stiffness. Our data further suggest that pharmacological inhibition of LIMK prevents vasoconstriction-induced arterial stiffening, in part, via reductions in vascular smooth muscle F-actin content and cellular stiffness. Accordingly, LIMK inhibition should represent a promising therapeutic means to stop the progression of arterial stiffening and remodeling in hypertension.

Williams syndrome hemideletion and LIMK1 variation both affect dorsal stream functional connectivity

Williams syndrome is a rare genetic disorder caused by hemizygous deletion of ∼1.6 Mb affecting 26 genes on chromosome 7 (7q11.23) and is clinically typified by two cognitive/behavioural hallmarks: marked visuospatial deficits relative to verbal and non-verbal reasoning abilities and hypersocial personality. Clear knowledge of the circumscribed set of genes that are affected in Williams syndrome, along with the well-characterized neurobehavioural phenotype, offers the potential to elucidate neurogenetic principles that may apply in genetically and clinically more complex settings. The intraparietal sulcus, in the dorsal visual processing stream, has been shown to be structurally and functionally altered in Williams syndrome, providing a target for investigating resting-state functional connectivity and effects of specific genes hemideleted in Williams syndrome. Here, we tested for effects of the LIMK1 gene, deleted in Williams syndrome and important for neuronal maturation and migration, on intraparietal sulcus functional connectivity. We first defined a target brain phenotype by comparing intraparietal sulcus resting functional connectivity in individuals with Williams syndrome, in whom LIMK1 is hemideleted, with typically developing children. Then in two separate cohorts from the general population, we asked whether intraparietal sulcus functional connectivity patterns similar to those found in Williams syndrome were associated with sequence variation of the LIMK1 gene. Four independent between-group comparisons of resting-state functional MRI data (total n = 510) were performed: (i) 20 children with Williams syndrome compared to 20 age- and sex-matched typically developing children; (ii) a discovery cohort of 99 healthy adults stratified by LIMK1 haplotype; (iii) a replication cohort of 32 healthy adults also stratified by LIMK1 haplotype; and (iv) 339 healthy adolescent children stratified by LIMK1 haplotype. For between-group analyses, differences in intraparietal sulcus resting-state functional connectivity were calculated comparing children with Williams syndrome to matched typically developing children and comparing LIMK1 haplotype groups in each of the three general population cohorts separately. Consistent with the visuospatial construction impairment and hypersocial personality that typify Williams syndrome, the Williams syndrome cohort exhibited opposite patterns of intraparietal sulcus functional connectivity with visual processing regions and social processing regions: decreased circuit function in the former and increased circuit function in the latter. All three general population groups also showed LIMK1 haplotype-related differences in intraparietal sulcus functional connectivity localized to the fusiform gyrus, a visual processing region also identified in the Williams syndrome-typically developing comparison. These results suggest a neurogenetic mechanism, in part involving LIMK1, that may bias neural circuit function in both the general population and individuals with Williams syndrome.

Collagens and elastin genetic variations and their potential role in aging-related diseases and longevity in humans

Collagens and elastin are 'building blocks' of tissues and extracellular matrix. Mutations in these proteins cause severe congenital syndromes. Adverse genetic variations may accelerate the aging process in adults contributing to premature morbidity, disability and/or mortality. Favorable variants may contribute to longevity and/or healthy aging, but this is much less studied. We reviewed the association between variation in the genes of collagens and elastin and premature aging, accelerated aging, age-related diseases and/or frailty; and the association between genetic variation in those and longevity and/or healthy aging in humans. A systematic search was conducted in MEDLINE and other online databases (OMIM, Genetics Home Reference, Orphanet, ClinVar). Results suggest that genetic variants lead to aging phenotypes of known congenital disease, but also to association with common age-related diseases in adults without known congenital disease. This may be due to the variable penetrance and expressivity of many variants. Some collagen variants have been associated with longevity or healthy aging. A limitation is that most studies had <1000 participants and their criterion for statistical significance was p < 0.05. Results highlight the importance of adopting a lifecourse approach to the study of the genomics of aging. Gerontology can help with new methodologies that operationalize biological aging.

Genetic basis of intracranial aneurysm formation and rupture: clinical implications in the postgenomic era

OBJECTIVE

Despite the prevalence and impact of intracranial aneurysms (IAs), the molecular basis of their pathogenesis remains largely unknown. Moreover, there is a dearth of clinically validated biomarkers to efficiently screen patients with IAs and prognosticate risk for rupture. The aim of this study was to survey the literature to systematically identify the spectrum of genetic aberrations that have been identified in IA formation and risk of rupture.

METHODS

A literature search was performed using the Medical Subject Headings (MeSH) system of databases including PubMed, EMBASE, and Google Scholar. Relevant studies that reported on genetic analyses of IAs, rupture risk, and long-term outcomes were included in the qualitative analysis.

RESULTS

A total of 114 studies were reviewed and 65 were included in the qualitative synthesis. There are several well-established mendelian syndromes that confer risk to IAs, with variable frequency. Linkage analyses, genome-wide association studies, candidate gene studies, and exome sequencing identify several recurrent polymorphic variants at candidate loci, and genes associated with the risk of aneurysm formation and rupture, including ANRIL (CDKN2B-AS1, 9p21), ARGHEF17 (11q13), ELN (7q11), SERPINA3 (14q32), and SOX17 (8q11). In addition, polymorphisms in eNOS/NOS3 (7q36) may serve as predictive markers for outcomes following intracranial aneurysm rupture. Genetic aberrations identified to date converge on posited molecular mechanisms involved in vascular remodeling, with strong implications for an associated immune-mediated inflammatory response.

CONCLUSIONS

Comprehensive studies of IA formation and rupture have identified candidate risk variants and loci; however, further genome-wide analyses are needed to identify high-confidence genetic aberrations. The literature supports a role for several risk loci in aneurysm formation and rupture with putative candidate genes. A thorough understanding of the genetic basis governing risk of IA development and the resultant aneurysmal subarachnoid hemorrhage may aid in screening, clinical management, and risk stratification of these patients, and it may also enable identification of putative mechanisms for future drug development.

Intracranial Aneurysms: Pathology, Genetics, and Molecular Mechanisms

Intracranial aneurysms (IA) are local dilatations in cerebral arteries that predominantly affect the circle of Willis. Occurring in approximately 2-5% of adults, these weakened areas are susceptible to rupture, leading to subarachnoid hemorrhage (SAH), a type of hemorrhagic stroke. Due to its early age of onset and poor prognosis, SAH accounts for > 25% of years lost for all stroke victims under the age of 65. In this review, we describe the cerebrovascular pathology associated with intracranial aneurysms. To understand IA genetics, we summarize syndromes with elevated incidence, genome-wide association studies (GWAS), whole exome studies on IA-affected families, and recent research that established definitive roles for Thsd1 (Thrombospondin Type 1 Domain Containing Protein 1) and Sox17 (SRY-box 17) in IA using genetically engineered mouse models. Lastly, we discuss the underlying molecular mechanisms of IA, including defects in vascular endothelial and smooth muscle cells caused by dysfunction in mechanotransduction, Thsd1/FAK (Focal Adhesion Kinase) signaling, and the Transforming Growth Factor β (TGF-β) pathway. As illustrated by THSD1 research, cell adhesion may play a significant role in IA.

Genetic Risk Factors for Intracranial Aneurysm in the Kazakh Population

An intracranial aneurysm (IA) is a weak or thin area on a blood vessel in the brain that balloons as it fills with blood. Genetic factors can influence the risk of developing an aneurism. The purpose of this study was to explore the relationship between single nucleotide polymorphisms (SNPs) and IA in Kazakh population. The patients were genotyped for 60 single nucleotide polymorphisms. Genotyping was performed on the QuantStudio 12K Flex (Life Technologies). A linear regression analysis found 13 SNPs' significant association with development and rupture of IA: the rs1800956 polymorphism of the ENG gene, rs1756 46 polymorphism of the JDP2 gene, variant rs1800255 of the COL3A1, rs4667622 of the UBR3, rs2374513 of the c12orf75, rs3742321 polymorphism of the StAR, the rs3782356 polymorphism of MLL2 gene, rs3932338 to 214 kilobases downstream of PRDM9, rs7550260 polymorphism of the ARHGEF, rs1504749 polymorphism of the SOX17, the rs173686 polymorphism of CSPG2 gene, rs6460071 located on LIMK1 gene, and the rs4934 polymorphism of SERPINA3. A total of 13 SNPs were identified as potential genetic markers for the development and risk of rupture of aneurysms in the Kazakh population. Similar results were obtained after adjusting for the confounding factors of arterial hypertension and age.

Identification of key genes, transcription factors and microRNAs involved in intracranial aneurysm

Intracranial aneurysm (IA) is a devastating disease, the pathogenesis of which remains to be elucidated. The present study aimed to determine the molecular mechanism of IA and to identify potential therapeutic targets using bioinformatics analysis. The GSE54083 dataset, which includes data from patients with ruptured IA and superficial temporal artery controls, was downloaded from the Gene Expression Omnibus, and differentially expressed genes (DEGs) were identified in the ruptured IA samples using the limma package in R. Subsequently, the Database for Annotation, Visualization and Integrated Discovery software was used to perform function and pathway enrichment analyses and the Search Tool for the Retrieval of Interacting Genes database was used to construct the protein‑protein interaction (PPI) network. Then, microRNA (miRNA) target and transcription factor (TF) target pairs were identified using the miR2Disease, MiRwalk2, ITFP and TRANSFAC databases. Finally, an integrated network of TF‑target‑miRNAs was constructed using Cytoscape. A total of 402 upregulated DEGs and 375 downregulated DEGs were identified from the ruptured IA samples compared with the superficial temporal artery samples. The majority of the upregulated DEGs were significantly enriched in the immune system development category, including CD40 ligand (CD40LG) and CD40 and the downregulated DEGs, such as striatin (STRN), were enriched in neuron projection development. In addition, nitric oxide synthase 1 (NOS1), a target of miRNA‑125b, and myosin heavy chain 11 (MYH11), a target of minichromosome maintenance complex component 4 (MCM4), had higher degree scores in the integrated network. These findings suggest that CD40, CD40LG, NOS1, STRN, MCM4, MYH11 and miR‑125b may be potential therapeutic targets for the treatment of IA.

Novel ELN mutation in a family with supravalvular aortic stenosis and intracranial aneurysm

Pathogenic germline mutations in ELN can be detected in patients with supravalvular aortic stenosis. The mutation might occur de novo or be inherited following an autosomal dominant pattern of inheritance. In this report we describe a three-generation family suffering from supravalvular aortic stenosis, various other arterial stenoses, sudden death, and intracranial aneurysms. A frameshift mutation in exon 12, not described before, was detected in the affected family members. This report emphasises the importance of family history, genetic counselling, and demonstrates the great variability in the phenotype within a single SVAS family.

Tetrahydro-pyrimido-indoles as selective LIMK inhibitors: synthesis, selectivity profiling and structure–activity studies

Extensive structure–activity studies on three different modification sites resulted in a series of LIM kinase inhibitors, containing a novel tricyclic hinge-binding motif based on the pyrrolopyrimidine scaffold.

The association of elastin gene variants with two angiographic subtypes of polypoidal choroidal vasculopathy

Objective

To compare the association of elastin (ELN) gene variants between two different angiographic phenotypes of polypoidal choroidal vasculopathy (PCV).

Methods

We included 411 treatment-naïve PCV patients and 350 controls in the present study. PCV was classified into two phenotypes (152 Type 1 and 259 Type 2) according to the presence or absence of feeding vessels found in indocyanine-green angiography. Single nucleotide polymorphisms (SNPs) in the ELN region including rs868005, rs884843, rs2301995, rs13239907 and rs2856728 were genotyped using TaqMan Genotyping Assays.

Results

In the allelic association analyses, rs868005 showed the strongest association with Type 2 PCV (allelic odds ratio 1.56; p = 7.4x10^-6), while no SNP was significantly associated with Type 1 PCV. Genotype association analyses revealed the significant association of rs868005 with Type 2 PCV in log additive model and predominant model (odds ratio 1.75; p = 1.5x10^-6 and odds ratio 1.60; p = 0.0044, respectively), but not with Type 1 PCV. These findings were further corroborated by another control group in the literature.

Conclusions

There may be significantly different associations in genetic variants of elastin between two angiographic phenotypes of PCV.

Molecular mechanisms of the formation and progression of intracranial aneurysms

Until recently, only a little was understood about molecular mechanisms of the development of an intracranial aneurysm (IA). Recent advancements over the last decade in the field of genetics and molecular biology have provided us a wide variety of evidences supporting the notion that chronic inflammation is closely associated with the pathogenesis of IA development. In the field of genetics, large-scale Genome-wide association studies (GWAS) has identified some IA susceptible loci and genes related to cell cycle and endothelial function. Researches in molecular biology using human samples and animal models have revealed the common pathway of the initiation, progression, and rupture of IAs. IA formation begins with endothelial dysfunction followed by pathological remodeling with degenerative changes of vascular walls. Medical treatments inhibiting inflammatory cascades in IA development are likely to prevent IA progression and rupture. Statins and aspirin are expected to suppress IA progression by their anti-inflammatory effects. Decoy oligodeoxynucleotides (ODNs) inhibiting inflammatory transcription factors such as nuclear factor kappa-B (NF-κB) and Ets-1 are the other promising choice of the prevention of IA development. Further clarification of molecular mechanisms of the formation and progression of IAs will shed light to the pathogenesis of IA development and provide insight into novel diagnostic and therapeutic strategies for IAs.

Bis-aryl urea derivatives as potent and selective LIM kinase (Limk) inhibitors

The discovery/optimization of bis-aryl ureas as Limk inhibitors to obtain high potency and selectivity and appropriate pharmacokinetic properties through systematic SAR studies is reported. Docking studies supported the observed SAR. Optimized Limk inhibitors had high biochemical potency (IC50 < 25 nM), excellent selectivity against ROCK and JNK kinases (>400-fold), potent inhibition of cofilin phosphorylation in A7r5, PC-3, and CEM-SS T cells (IC50 < 1 μM), and good in vitro and in vivo pharmacokinetic properties. In the profiling against a panel of 61 kinases, compound 18b at 1 μM inhibited only Limk1 and STK16 with ≥80% inhibition. Compounds 18b and 18f were highly efficient in inhibiting cell-invasion/migration in PC-3 cells. In addition, compound 18w was demonstrated to be effective on reducing intraocular pressure (IOP) on rat eyes. Taken together, these data demonstrated that we had developed a novel class of bis-aryl urea derived potent and selective Limk inhibitors.

BDNF repairs podocyte damage by microRNA-mediated increase of actin polymerization

Idiopathic focal segmental glomerulosclerosis (FSGS) is a progressive and proteinuric kidney disease that starts with podocyte injury. Podocytes cover the external side of the glomerular capillary by a complex web of primary and secondary ramifications. Similar to dendritic spines of neuronal cells, podocyte processes rely on a dynamic actin-based cytoskeletal architecture to maintain shape and function. Brain-derived neurotrophic factor (BDNF) is a pleiotropic neurotrophin that binds to the tropomyosin-related kinase B receptor (TrkB) and has crucial roles in neuron maturation, survival, and activity. In neuronal cultures, exogenously added BDNF increases the number and size of dendritic spines. In animal models, BDNF administration is beneficial in both central and peripheral nervous system disorders. Here we show that BDNF has a TrkB-dependent trophic activity on podocyte cell processes; by affecting microRNA-134 and microRNA-132 signalling, BDNF up-regulates Limk1 translation and phosphorylation, and increases cofilin phosphorylation, which results in actin polymerization. Importantly, BDNF effectively repairs podocyte damage in vitro, and contrasts proteinuria and glomerular lesions in in vivo models of FSGS, opening a potential new perspective to the treatment of podocyte disorders.

Molecular basis and genetic predisposition to intracranial aneurysm

Intracranial aneurysms, also called cerebral aneurysms, are dilatations in the arteries that supply blood to the brain. Rupture of an intracranial aneurysm leads to a subarachnoid hemorrhage, which is fatal in about 50% of the cases. Intracranial aneurysms can be repaired surgically or endovascularly, or by combining these two treatment modalities. They are relatively common with an estimated prevalence of unruptured aneurysms of 2%-6% in the adult population, and are considered a complex disease with both genetic and environmental risk factors. Known risk factors include smoking, hypertension, increasing age, and positive family history for intracranial aneurysms. Identifying the molecular mechanisms underlying the pathogenesis of intracranial aneurysms is complex. Genome-wide approaches such as DNA linkage and genetic association studies, as well as microarray-based mRNA expression studies, provide unbiased approaches to identify genetic risk factors and dissecting the molecular pathobiology of intracranial aneurysms. The ultimate goal of these studies is to use the information in clinical practice to predict an individual's risk for developing an aneurysm or monitor its growth or rupture risk. Another important goal is to design new therapies based on the information on mechanisms of disease processes to prevent the development or halt the progression of intracranial aneurysms.

A conserved region in the 3' untranslated region of the human LIMK1 gene is critical for proper expression of LIMK1 at the post-transcriptional level

LIM kinase 1 (LIMK1), a cytosolic serine/threonine kinase, regulates actin filament dynamics and reorganization and is involved in neuronal development and brain function. Abnormal expression of LIMK1 is associated with several neurological disorders. In this study, we performed a conservation analysis using Vector NTI (8.0) software. The dualluciferase reporter assay and real-time quantitative RT-PCR were used to assess the protein and mRNA levels of the reporter gene, respectively. We found that a region ranging from nt +884 to +966 in the human LIMK1 3' untranslated region (UTR) was highly conserved in the mouse Limk1 3' UTR and formed a structure containing several loops and stems. Luciferase assay showed that the relative luciferase activity of the mutated construct with the conserved region deleted, pGL4-hLIMK1-3U-M, in SH-SY5Y and HEK-293 cells was only ~60% of that of the wild-type construct pGL4-hLIMK1-3U, indicating that the conserved region is critical for the reporter gene expression. Real-time quantitative RT-PCR analysis demonstrated that the relative Luc2 mRNA levels in SH-SY5Y and HEK293 cells transfected with pGL4-hLIMK1-3U-M decreased to ~50% of that in cells transfected with pGL4-hLIMK1-3U, suggesting an important role of the conserved region in maintaining Luc2 mRNA stability. Our study suggests that the conserved region in the LIMK1 3' UTR is involved in regulating LIMK1 expression at the post-transcriptional level, which may help reveal the mechanism underlying the regulation of LIMK1 expression in the central nervous system and explore the relationship between the 3'-UTR mutant and neurological disorders.

Polymorphisms in the human tropoelastin gene modify in vitro self-assembly and mechanical properties of elastin-like polypeptides

Elastin is a major structural component of elastic fibres that provide properties of stretch and recoil to tissues such as arteries, lung and skin. Remarkably, after initial deposition of elastin there is normally no subsequent turnover of this protein over the course of a lifetime. Consequently, elastic fibres must be extremely durable, able to withstand, for example in the human thoracic aorta, billions of cycles of stretch and recoil without mechanical failure. Major defects in the elastin gene (ELN) are associated with a number of disorders including Supravalvular aortic stenosis (SVAS), Williams-Beuren syndrome (WBS) and autosomal dominant cutis laxa (ADCL). Given the low turnover of elastin and the requirement for the long term durability of elastic fibres, we examined the possibility for more subtle polymorphisms in the human elastin gene to impact the assembly and long-term durability of the elastic matrix. Surveys of genetic variation resources identified 118 mutations in human ELN, 17 being non-synonymous. Introduction of two of these variants, G422S and K463R, in elastin-like polypeptides as well as full-length tropoelastin, resulted in changes in both their assembly and mechanical properties. Most notably G422S, which occurs in up to 40% of European populations, was found to enhance some elastomeric properties. These studies reveal that even apparently minor polymorphisms in human ELN can impact the assembly and mechanical properties of the elastic matrix, effects that over the course of a lifetime could result in altered susceptibility to cardiovascular disease.

HIV-1 proteins join the family of LIM kinase partners. New roads open up for HIV-1 treatment

LIM kinases (LIMK) exert their functions by recruiting many macromolecular partners that could contribute to modulate LIMK activity in a positive or negative manner. In addition to proteins that interact with LIMK in human or animal cells and tissues, recent data show that LIMK activity is also influenced by HIV-1 viral proteins. These results suggest new strategies for the treatment of HIV-1 infection, based on the inhibition of LIMK-mediated cofilin inactivation and consequent actin depolymerization. Further efforts are however required to unravel the mechanism by which the virus interferes with LIMK activity and with the right balance of actin remodeling.

Common genetic polymorphisms in moyamoya and atherosclerotic disease in Europeans

PURPOSE

Moyamoya is the most common cerebrovascular disease in children in Japan. The disease's etiology is still widely unknown. Several publications describe histopathological changes in the walls of affected vessels similar to those seen in atherosclerosis. In this study, we analyzed the DNA of European patients with Moyamoya disease for single nucleotide polymorphisms associated with atherosclerotic changes.

METHODS

We genotyped 17 SNPs in or adjacent to 11 genes (ELN, LIMK1, CDKN2A/B, CXCL12, Pseudogene ENSG00000197218, PSRC1, MTHFD1L, SMAD3, MIA3, PDGF-B, TIMP2) comparing 40 DNA samples of Moyamoya disease patients to 68 healthy controls from central Europe. The mean age of onset of Moyamoya disease (MMD)-related symptoms was 15.4 years of age. Genotyping was performed by sequencing the SNP containing genetic regions with custom-made primers.

RESULTS

We found strong association of one SNP (rs599839 [A/G], OR = 2.17, 95% CI = 1.17, 4.05; p = 0.01) with the risk allele G located in the 3' UTR region of the PSRC-1 gene. Three further SNPs (rs8326, rs34208922, rs501120) in or adjacent to the genes ELN and CXCL12 showed tendencies towards risk alleles with p values between 0.1 and 0.2 but did not reach statistical significance in our cohort.

CONCLUSIONS

Our results indicate a possible parallel of common processes in the genesis of Moyamoya disease and atherosclerotic disease. Further analyses in larger European cohorts and replication in patients of different ethnicity may lead to possible early detection of patients at risk for developing MMD and subsequently to future causative therapies.

LIM kinases are attractive targets with many macromolecular partners and only a few small molecule regulators

The LIM kinases 1 and 2 (LIMK1 and LIMK2) are dual specificity (serine/threonine and tyrosine) kinases. Although they show significant structural similarity, LIMK1 and LIMK2 show different expression, subcellular localization, and functions. They are involved in many cellular functions, such as migration, cycle, and neuronal differentiation and also have a role in pathological processes, such as cancer cell invasion and metastatis, as well as in neurodevelopmental disorders (namely, the William's syndrome). LIM kinases have a relevant number of known partners that are able to induce or limit the ability of LIMK1 and LIMK2 to phosphorylate and inactivate their major substrate, cofilin. On the contrary, only a limited number of small molecules that interact with the two proteins to modulate their kinase activity have been identified. In this review, the most important partners of LIM kinases and their modulating activity toward LIMKs are described. The small compounds identified as LIMK1 and LIMK2 modulators are also reported, as well as their role as possible therapeutic agents for LIMK-induced diseases.

Impact of LIMK1, MMP2 and TNF-α variations for intracranial aneurysm in Japanese population

Genetic factors are known to have an important role in intracranial aneurysm (IA) pathogenesis. The purpose of this study is to identify single-nucleotide polymorphisms (SNPs) that are associated with IA in Japanese population. A total of 2050 IA patients and 1835 controls recruited in Biobank Japan, The University of Tokyo were used in this study. In all, 45 SNPs in 24 genes encoding proteins, which have been considered to be possible risk factors to IA pathogenesis, were genotyped using multiplex PCR-invader assay. Association analysis was evaluated by logistic regression analysis before and after adjustment of age, smoking and hypertension status. This case-control association study revealed a SNP, rs6460071 located on LIMK1 gene (P = 0.00069) to be significantly associated with increased risk of IA. In addition, two SNPs, rs243847 (P = 0.00086) and rs243865 (P = 0.00090), on matrix metallopeptidase 2 (MMP2) gene and one SNP rs1799724 (P = 0.0026) on tumor necrosis factor-α (TNF-α) gene, are marginally associated with IA in male- and female-specific manner, respectively. In conclusion, a large-scale case-control association study was conducted to verify genetic variations associated with IA in Japanese population. This study gave insights on the importance of stratified analysis between genders, and suggested that the underlying mechanism of IA pathogenesis might differ between females and males.

A study on polymorphisms of elastin gene in Chinese Han patients with isolated systolic hypertension

BACKGROUND

Elastin (ELN) is mainly located in the internal elastic lamina of large arteries. Degradation of ELN is expected to induce large vessel stiffness, which could lead to elderly systolic hypertension. Recent studies have shown that polymorphism of ELN is associated with stiffness of elastic arteries and elevated blood pressure; however, there are no further studies on isolated systolic hypertension (ISH).

METHODS

We identified the genotype of the ELN gene in 358 patients with ISH, 413 essential hypertension (EH) patients with elevated diastolic blood pressure (DBP), and 244 age-matched normotensive (NT) controls for five single-nucleotide polymorphisms (SNPs) and detected the brachial-ankle pulse wave velocity (baPWV), C-reactive protein (CRP), and intima-media thickness (IMT) for these patients.

RESULTS

ISH was statistically significant in association with SNP rs34208922 (A allele frequency was 0.068 in ISH patients, 0.036 in EH patients, and 0.014 in NT controls; P < 0.001, P(corr) < 0.005) and possibly with SNP rs2071307 (A allele frequency was 0.103 in ISH patients, 0.079 in EH patients, and 0.047 in NT controls; P = 0.002, P(corr) = 0.01), however, the A allele frequency was not different between ISH patients and EH patients. In addition, baPWV and CRP were significantly associated with SNP rs34208922 and rs2071307. The other three SNPs were not significantly associated with ISH, baPWV, CRP, or IMT. Haplotypes of TGGTA and TGAT- were also significantly associated with ISH (P = 0.0001, P(corr) = 0.0021; P = 0.0023, P(corr) = 0.0483).

CONCLUSIONS

Variants within the ELN gene are associated with increased risk of ISH and aortic stiffness in the Chinese Han population.

Molecular Genetics of Human Intracranial Aneurysms

Intracranial aneurysms (IAs) are the dilatations of blood vessels in the brain and pose potential risk of rupture leading to subarachnoid hemorrhage. Although the genetic basis of IAs is poorly understood, it is well-known that genetic factors play an important part in the pathogenesis of IAs. Therefore, the identifying susceptible genetic variants might lead to the understanding of the mechanism of formation and rupture of IAs and might also lead to the development of a pharmacological therapy. To elucidate the molecular pathogenesis of diseases has become a crucial step in the development of new treatment strategies. Although extensive genetic research and its potential implications for future prevention of this often fatal condition are urgently needed, efforts to elucidate the susceptibility loci of IAs are hindered by the issues bewildering the most common and complex genetic disorders, such as low penetrance, late onset, and uncertain modes of inheritance. These efforts are further complicated by the fact that many IA lesions remain asymptomatic or go undiagnosed. In this review, we present and discuss the current status of genetic studies of IAs and we recommend comprehensive genome-wide association studies to identify genetic loci that underlie this complex disease.

Mechanisms and treatment of cardiovascular disease in Williams-Beuren syndrome

Williams-Beuren syndrome (WBS) is a microdeletion disorder caused by heterozygous loss of approximately 1.5-Mb pairs of DNA from chromosome 7. Patients with WBS have a characteristic constellation of medical and cognitive findings, with a hallmark feature of generalized arteriopathy presenting as stenoses of elastic arteries and hypertension. Human and mouse studies establish that defects in the elastin gene, leading to elastin haploinsufficiency, underlie the arteriopathy. In this review we describe potential links between elastin expression and arteriopathy, possible explanations for disease variability, and current treatment options and their limitations, and we propose several new directions for the development of nonsurgical preventative therapies based on insights from elastin biology.

Genome screen to detect linkage to intracranial aneurysm susceptibility genes: the Familial Intracranial Aneurysm (FIA) study

BACKGROUND AND PURPOSE

Evidence supports a substantial genetic contribution to the risk of intracranial aneurysm (IA). The purpose of this study was to identify chromosomal regions likely to harbor genes that contribute to the risk of IA.

METHODS

Multiplex families having at least 2 individuals with "definite" or "probable" IA were ascertained through an international consortium. First-degree relatives of individuals with IA who were at increased risk of an IA because of a history of hypertension or present smoking were offered cerebral magnetic resonance angiography. A genome screen was completed using the Illumina 6K SNP system, and the resulting data from 192 families, containing 1155 genotyped individuals, were analyzed. Narrow and broad disease definitions were used when testing for linkage using multipoint model-independent methods. Ordered subset analysis was performed to test for a gene x smoking (pack-years) interaction.

RESULTS

The greatest evidence of linkage was found on chromosomes 4 (LOD=2.5; 156 cM), 7 (LOD=1.7; 183 cM), 8 (LOD=1.9; 70 cM), and 12 (LOD=1.6; 102 cM) using the broad disease definition. Using the average pack-years for the affected individuals in each family, the genes on chromosomes 4 (LOD=3.5; P=0.03), 7 (LOD=4.1; P=0.01) and 12 (LOD=3.6; P=0.02) all appear to be modulated by the degree of smoking in the affected members of the family. On chromosome 8, inclusion of smoking as a covariate did not significantly strengthen the linkage evidence, suggesting no interaction between the loci in this region and smoking.

CONCLUSIONS

We have detected possible evidence of linkage to 4 chromosomal regions. There is potential evidence for a gene x smoking interaction with 3 of the loci.

Analysis of the 5q31 33 locus shows an association between single nucleotide polymorphism variants in the IL-5 gene and symptomatic infection with the human blood fluke, Schistosoma japonicum

Genetic studies of human susceptibility to Schistosoma (blood fluke) infections have previously identified a genetic locus determining infection intensity with the African species, Schistosoma mansoni, in the 5q31-33 region of the human genome that is known to contain the Th2 immune response cluster, including the genes encoding the IL-4, IL-5, and IL-13 cytokines. These cytokines are key players in inflammatory immune responses and have previously been implicated in human susceptibility to infection with the Asian species, S. japonicum. In a nested case control study, we genotyped 30 HapMap tagging single nucleotide polymorphisms (SNPs) across these three genes in 159 individuals identified as putatively susceptible to reinfection with S. japonicum and in 133 putatively resistant individuals. A third group comprising 113 individuals demonstrating symptomatic infection was also included. The results provided no significant association at a global level between reinfection predisposition and any of the individual SNPs or haplotype blocks. However, two tagging SNPs in IL-5 demonstrated globally significant association with susceptibility to symptomatic infection. They were in strong linkage disequilibrium with each other and were found to belong to the same haplotype block that also provided a significant association after permutation testing. This haplotype was located in the 3'-untranslated region of IL-5, suggesting that variants in this region of IL-5 may modulate the immune response in these individuals with symptomatic infection.

Association analyses confirming a susceptibility locus for intracranial aneurysm at chromosome 14q23

Previous linkage analyses of intracranial aneurysm (IA) have proposed several genetic susceptibility loci; however, some loci remain contradictory. The objective of this study was to confirm these loci in a Japanese population using allelic and haplotype association analyses. We set high-density single nucleotide polymorphism markers in previously suggested IA loci and conducted an association analysis in 29 cases and 35 controls from a small community in Akita, Japan. Genotyping was carried out using the GeneChip 10 K mapping array, and the association analysis was performed using GeneSpring GT2 software. The result was confirmed in a replication cohort consisting of 237 cases and 253 controls from all over Japan. Only one variant, rs767603, at chromosome 14q23, was significantly associated with IA, both in allelic analysis (p=0.00017, Bonferroni-corrected p=0.021) and haplotype analysis (p=0.00178, Bonferroni-corrected p=0.048). This association was confirmed in the replication cohort (p=0.0046 for allelic association, p=0.0060 for haplotype association). Our findings confirm 14q23 to be a susceptibility locus for intracranial aneurysm.

The influence of genetics on intracranial aneurysm formation and rupture: current knowledge and its possible impact on future treatment

The etiology of intracranial aneurysm formation and rupture remains mostly unknown, but lately several studies have increasingly supported the role of genetic factors. In reports so far, genome-wide linkage studies suggest several susceptibility loci that may contain one or more predisposing genes. Depending on the examined ethnic population, several different non-matching chromosomal regions have been found. Studies of several candidate genes report association with intracranial aneurysms. To date, no single gene has been identified as responsible for intracranial aneurysm formation or rupture. In addition to the well-published environmental factors, such as alcohol intake, hypertension and smoking, only the recent progress in molecular genetics enables us to investigate the possible genetic determinants of this disease. Although a familial predisposition is the strongest risk factor for the development of intracranial aneurysms, the mode of Mendelian inheritance is uncertain in most families. Therefore, multiple genetic susceptibilities in conjunction with the environmental factors are considered to act together in the disease's etiology. Accordingly, researchers performed linkage studies and case-control association studies for the genetic analysis and have identified several genes to be susceptible to intracranial aneurysms. The identification of susceptible genes may lead to the understanding of the mechanism of formation and rupture and possibly lead to the development of a pharmacological therapy. Furthermore, should it be possible to identify a genetic marker associated with an increased risk of formation and rupture of an intracranial aneurysm, the necessity for screening and urgency of treatment could be determined more easily. In this review we summarize the current knowledge of intracranial aneurysm genetics and also discuss the method to detect the causalities. In view of the recent advances made in this field, we also give an outlook on possible future genetically engineered therapies, whose development are well underway.

Association of Kallikrein Gene Polymorphisms With Intracranial Aneurysms

Background and Purpose— Genomewide DNA linkage analysis identified a susceptibility locus for intracranial aneurysm (IA) on chromosome 19q13 in the Finnish population, a region including the kallikrein gene cluster. We investigated the association of single nucleotide polymorphisms (SNPs) in the kallikrein gene cluster with IA in the Finnish population.

Methods— We genotyped 18 haplotype-tagging SNPs spanning a 244 kbp region in the kallikrein gene cluster for 266 Finnish IA cases and 290 Finnish control subjects. In a second phase, we genotyped 2 SNPs (rs1722561 and rs1701946) in an additional set of 102 Finnish IA cases and 102 Finnish control subjects; and in a third phase, we genotyped these 2 SNPs in 156 Russian IA cases and 186 Russian control subjects. Both single-marker and haplotype-based tests of association were performed.

Results— In phase I, SNPs rs1722561 and rs1701946 were significantly associated with IA in the Finnish population for single locus models (rs1722561: P =0.0395; rs1701946: P =0.0253). A 2-SNP haplotype block (rs1722561–rs1701946) identified in phase I was also associated with IA in the expanded Finnish (phase II) data set (asymptotic P =0.012; empirical P =0.019). In the Finnish and Russian combined data set (phase III) with 524 cases and 578 control subjects, the same 2 SNPs (OR: 1.35, 95% CI: 1.14, 1.60; P =0.0005 for rs1722561 and OR: 1.32, 95% CI: 1.12, 1.57; P =0.0011 for rs1701946) were significantly associated with IA. These SNPs are located in the intronic region of KLK8 , although linkage disequilibrium could extend from rs268912–rs2250066, a ≈76-kbp region that includes KLK5–KLK10.

Conclusions— Polymorphisms within the kallikrein gene cluster are associated with IA suggesting that the kallikreins are important candidate genes for IA.

LIM kinases: function, regulation and association with human disease

The LIM kinase family consists of just two members: LIM kinase 1 (LIMK1) and LIM kinase 2 (LIMK2). With uniquely organised signalling domains, LIM kinases are regulated by several upstream signalling pathways, principally acting downstream of Rho GTPases to influence the architecture of the actin cytoskeleton by regulating the activity of the cofilin family proteins cofilin1, cofilin2 and destrin. Although the LIM kinases are very homologous, particularly when comparing kinase domains, there is emerging evidence that each may be subject to different regulatory pathways and may contribute to both distinct and overlapping cellular and developmental functions. Normal central nervous system development is reliant upon the presence of LIMK1, and its deletion has been implicated in the development of the human genetic disorder Williams syndrome. Normal testis development, on the other hand, is disrupted by the deletion of LIMK2. In addition, the possible involvement of each kinase in cardiovascular disorders as well as cancer has recently emerged. The LIM kinases have been proposed to play an important role in tumour-cell invasion and metastasis; fine-tuning the balance between phosphorylated and non-phosphorylated cofilin may be a significant determinant of tumour-cell metastatic potential. In this review, we outline the structure, regulation and function of LIM kinases and their functions at cellular and organismal levels, as well as their possible contributions to human disease.

Systematic screening of lysyl oxidase-like (LOXL) family genes demonstrates that LOXL2 is a susceptibility gene to intracranial aneurysms

Four lysyl oxidase family genes (LOXL1, LOXL2, LOXL3, and LOXL4), which catalyze cross-linking of collagen and elastin, were considered to be functional candidates for intracranial aneurysms (IA) and were extensively screened for genetic susceptibility in Japanese IA patients. Total RNA was isolated from four paired ruptured IA and superficial temporal artery (STA) tissue and examined by real-time RT-PCR. The expression of LOXL2 in the paired IA and STA tissues was elevated in the IA tissue. A total of 55 single nucleotide polymorphisms (SNPs) of LOXL1-4 were genotyped for an allelic association study in 402 Japanese IA patients and 462 Japanese non-IA controls. Allelic associations were evaluated with the chi-square test and the permutation test especially designed for adjustment of multiple testing. SNPs of LOXL1 and LOXL4 were not significantly associated with IA, while several SNPs of LOXL2 and LOXL3 showed nominally significant associations in IA patients. We detected an empirically significant association with one SNP of LOXL2 in familial IA patients after adjustment for multiple testing [chi(2) = 10.23, empirical P = 0.023, OR (95% CI) = 1.49 (1.17, 1.90)]. Furthermore, multilocus interaction was evaluated by multifactor dimensionality reduction analysis. We found that the SNPs of LOXL2 have an interactive effect with elastin (ELN) and LIM kinase 1 (LIMK1) that have been previously found to be associated with IA. In conclusion, one SNP of LOXL2 showed a significant association with IA individually, and we also detected a gene-gene interaction of LOXL2 with ELN/LIMK1, which may play an important role in susceptibility to IA.