Lemur tyrosine kinase-2 signalling regulates kinesin-1 light chain-2 phosphorylation and binding of Smad2 cargo.

A recent genome-wide association study identified the gene encoding lemur tyrosine kinase-2 (LMTK2) as a susceptibility gene for prostate cancer. The identified genetic alteration is within intron 9, but the mechanisms by which LMTK2 may impact upon prostate cancer are not clear because the functions of LMTK2 are poorly understood. Here, we show that LMTK2 regulates a known pathway that controls phosphorylation of kinesin-1 light chain-2 (KLC2) by glycogen synthase kinase-3β (GSK3β). KLC2 phosphorylation by GSK3β induces the release of cargo from KLC2. LMTK2 signals via protein phosphatase-1C (PP1C) to increase inhibitory phosphorylation of GSK3β on serine-9 that reduces KLC2 phosphorylation and promotes binding of the known KLC2 cargo Smad2. Smad2 signals to the nucleus in response to transforming growth factor-β (TGFβ) receptor stimulation and transport of Smad2 by kinesin-1 is required for this signalling. We show that small interfering RNA loss of LMTK2 not only reduces binding of Smad2 to KLC2, but also inhibits TGFβ-induced Smad2 signalling. Thus, LMTK2 may regulate the activity of kinesin-1 motor function and Smad2 signalling

Alterations in LMTK2, MSMB and HNF1B gene expression are associated with the development of prostate cancer

<p>Abstract</p> <p>Background</p> <p>Genome wide association studies (GWAS) have identified several genetic variants that are associated with prostate cancer. Most of these variants, like other GWAS association signals, are located in non-coding regions of potential candidate genes, and thus could act at the level of the mRNA transcript.</p> <p>Methods</p> <p>We measured the expression and isoform usage of seven prostate cancer candidate genes in benign and malignant prostate by real-time PCR, and correlated these factors with cancer status and genotype at the GWAS risk variants.</p> <p>Results</p> <p>We determined that levels of <it>LMTK2 </it>transcripts in prostate adenocarcinomas were only 32% of those in benign tissues (p = 3.2 × 10^-7), and that an independent effect of genotype at variant rs6465657 on <it>LMTK2 </it>expression in benign (n = 39) and malignant tissues (n = 21) was also evident (P = 0.002). We also identified that whilst <it>HNF1B(C) </it>and <it>MSMB2 </it>comprised the predominant isoforms in benign tissues (90% and 98% of total <it>HNF1B </it>or <it>MSMB </it>expression)<it>, HNF1B(B) and MSMB1 </it>were predominant in malignant tissue (95% and 96% of total <it>HNF1B </it>or <it>MSMB </it>expression; P = 1.7 × 10^-7and 4 × 10^-4respectively), indicating major shifts in isoform usage.</p> <p>Conclusions</p> <p>Our results indicate that the amount or nature of mRNA transcripts expressed from the <it>LMTK2</it>, <it>HNF1B </it>and <it>MSMB </it>candidate genes is altered in prostate cancer, and provides further evidence for a role for these genes in this disorder. The alterations in isoform usage we detect highlights the potential importance of alternative mRNA processing and moderation of mRNA stability as potentially important disease mechanisms.</p

Previously described sequence variant in CDK5RAP2 gene in a Pakistani family with autosomal recessive primary microcephaly

<p>Abstract</p> <p>Background</p> <p>Autosomal Recessive Primary Microcephaly (MCPH) is a disorder of neurogenic mitosis. MCPH leads to reduced cerebral cortical volume and hence, reduced head circumference associated with mental retardation of variable degree. Genetic heterogeneity is well documented in patients with MCPH with six loci known, while pathogenic sequence variants in four respective genes have been identified so far. Mutations in <it>CDK5RAP2 </it>gene at MCPH3 locus have been least involved in causing MCPH phenotype.</p> <p>Methods</p> <p>All coding exons and exon/intron splice junctions of <it>CDK5RAP2 </it>gene were sequenced in affected and normal individuals of Pakistani MCPH family of Kashmiri origin, which showed linkage to MCPH3 locus on chromosome 9q33.2.</p> <p>Results</p> <p>A previously described nonsense mutation [243 T>A (S81X)] in exon 4 of <it>CDK5RAP2 </it>gene has been identified in the Pakistani family, presented here, with MCPH Phenotype. Genomic and cDNA sequence comparison revealed that the exact nomenclature for this mutation is 246 T>A (Y82X).</p> <p>Conclusion</p> <p>Recurrent observation of Y82X mutation in <it>CDK5RAP2 </it>gene in this Pakistani family may be a sign of confinement of a rare ancestral haplotype carrying this pathogenic variant within Northern Pakistani population, as this has not been reported in any other population.</p

Specific inhibition of p25/Cdk5 activity by the Cdk5 inhibitory peptide reduces neurodegeneration in vivo

The aberrant hyperactivation of Cyclin-dependent kinase 5 (Cdk5), by the production of its truncated activator p25, results in the formation of hyperphosphorylated tau, neuroinflammation, amyloid deposition, and neuronal death in vitro and in vivo. Mechanistically, this occurs as a result of a neurotoxic insult that invokes the intracellular elevation of calcium to activate calpain, which cleaves the Cdk5 activator p35 into p25. It has been shown previously that the p25 transgenic mouse as a model to investigate the mechanistic implications of p25 production in the brain, which recapitulates deregulated Cdk5-mediated neuropathological changes, such as hyperphosphorylated tau and neuronal death. To date, strategies to inhibit Cdk5 activity have not been successful in targeting selectively aberrant activity without affecting normal Cdk5 activity. Here we show that the selective inhibition of p25/Cdk5 hyperactivation in vivo, through overexpression of the Cdk5 inhibitory peptide (CIP), rescues against the neurodegenerative pathologies caused by p25/Cdk5 hyperactivation without affecting normal neurodevelopment afforded by normal p35/Cdk5 activity. Tau and amyloid pathologies as well as neuroinflammation are significantly reduced in the CIP-p25 tetra transgenic mice, whereas brain atrophy and subsequent cognitive decline are reversed in these mice. The findings reported here represent an important breakthrough in elucidating approaches to selectively inhibit the p25/Cdk5 hyperactivation as a potential therapeutic target to reduce neurodegeneration

Lanosterol induces mitochondrial uncoupling and protects dopaminergic neurons from cell death in a model for Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder marked by the selective degeneration of dopaminergic neurons in the nigrostriatal pathway. Several lines of evidence indicate that mitochondrial dysfunction contributes to its etiology. Other studies have suggested that alterations in sterol homeostasis correlate with increased risk for PD. Whether these observations are functionally related is, however, unknown. In this study, we used a toxin-induced mouse model of PD and measured levels of nine sterol intermediates. We found that lanosterol is significantly (∼50%) and specifically reduced in the nigrostriatal regions of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice, indicative of altered lanosterol metabolism during PD pathogenesis. Remarkably, exogenous addition of lanosterol rescued dopaminergic neurons from 1-methyl-4-phenylpyridinium (MPP+)-induced cell death in culture. Furthermore, we observed a marked redistribution of lanosterol synthase from the endoplasmic reticulum to mitochondria in dopaminergic neurons exposed to MPP+, suggesting that lanosterol might exert its survival effect by regulating mitochondrial function. Consistent with this model, we find that lanosterol induces mild depolarization of mitochondria and promotes autophagy. Collectively, our results highlight a novel sterol-based neuroprotective mechanism with direct relevance to PD

Nerve Growth Factor Stimulates Interaction of Cayman Ataxia Protein BNIP-H/Caytaxin with Peptidyl-Prolyl Isomerase Pin1 in Differentiating Neurons

Mutations in ATCAY that encodes the brain-specific protein BNIP-H (or Caytaxin) lead to Cayman cerebellar ataxia. BNIP-H binds to glutaminase, a neurotransmitter-producing enzyme, and affects its activity and intracellular localization. Here we describe the identification and characterization of the binding between BNIP-H and Pin1, a peptidyl-prolyl cis/trans isomerase. BNIP-H interacted with Pin1 after nerve growth factor-stimulation and they co-localized in the neurites and cytosol of differentiating pheochromocytoma PC12 cells and the embryonic carcinoma P19 cells. Deletional mutagenesis revealed two cryptic binding sites within the C-terminus of BNIP-H such that single point mutants affecting the WW domain of Pin1 completely abolished their binding. Although these two sites do not contain any of the canonical Pin1-binding motifs they showed differential binding profiles to Pin1 WW domain mutants S16E, S16A and W34A, and the catalytically inert C113A of its isomerase domain. Furthermore, their direct interaction would occur only upon disrupting the ability of BNIP-H to form an intramolecular interaction by two similar regions. Furthermore, expression of Pin1 disrupted the BNIP-H/glutaminase complex formation in PC12 cells under nerve growth factor-stimulation. These results indicate that nerve growth factor may stimulate the interaction of BNIP-H with Pin1 by releasing its intramolecular inhibition. Such a mechanism could provide a post-translational regulation on the cellular activity of BNIP-H during neuronal differentiation. (213 words

A Fluorescent Glycolipid-Binding Peptide Probe Traces Cholesterol Dependent Microdomain-Derived Trafficking Pathways

10.1371/journal.pone.0002933PLoS ONE38

Asean integration : a work in progress, not an 'illusion'

ASEAN and its integrative processes are working well, albeit at less than desired speed. However, the real worth and value of ASEAN is the consciousness that has been developed among ministers, officials and NGO representatives of thinking in regional terms