Genetic variation in human NPY expression affects stress response and emotion

Understanding inter- individual differences in stress response requires the explanation of genetic influences at multiple phenotypic levels, including complex behaviours and the metabolic responses of brain regions to emotional stimuli. Neuropeptide Y ( NPY) is anxiolytic(1,2) and its release is induced by stress(3). NPY is abundantly expressed in regions of the limbic system that are implicated in arousal and in the assignment of emotional valences to stimuli and memories(4-6). Here we show that haplotype- driven NPY expression predicts brain responses to emotional and stress challenges and also inversely correlates with trait anxiety. NPY haplotypes predicted levels of NPY messenger RNA in postmortem brain and lymphoblasts, and levels of plasma NPY. Lower haplotype- driven NPY expression predicted higher emotion- induced activation of the amygdala, as well as diminished resiliency as assessed by pain/ stress- induced activations of endogenous opioid neurotransmission in various brain regions. A single nucleotide polymorphism ( SNP rs16147) located in the promoter region alters NPY expression in vitro and seems to account for more than half of the variation in expression in vivo. These convergent findings are consistent with the function of NPY as an anxiolytic peptide and help to explain inter- individual variation in resiliency to stress, a risk factor for many diseases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62768/1/nature06858.pd

Tuning Molecular Weights of <i>Bombyx mori (B. mori)</i> Silk Sericin to Modify Its Assembly Structures and Materials Formation

<i>Bombyx mori (B. mori)</i> silk sericin is a protein with features desirable as a biomaterial, such as increased hydrophilicity and biodegradation, as well as resistance to oxidation, bacteria, and ultraviolet light. In contrast to other widely studied <i>B. mori</i> silk proteins such as fibroin, sericin is still unexplored as a building block for fabricating biomaterial, and thus a facile technique of processing it into a material is needed. Here, electrospinning technology was used to fabricate it into biomaterials from two forms of <i>B. mori</i> silk sericin with different molecular weights, one is a low (12.0 kDa) molecular sericin (LS) form and another is a high (66.0 kDa) molecular weight sericin (HS) form. Circular dichroism (CD) spectra showed that LS in hexafluoroacetone (HFA) solvent adopted a predominantly random coil conformation, whereas HS tended to form a β-sheet structure along with a large content of random coils. In addition, LS and HS in HFA solvent were found to form cylinder-like smaller nanoparticles and larger irregular aggregates before electrospinning, respectively. As a result, biomaterials based on microparticles and nanofibers were successfully fabricated by electrospinning of LS and HS dissolved in HFA, respectively. The cell viability and differentiation assay indicated that nanofibers and microparticles improved cell adhesion, growth, and differentiation, proving that the scaffolds electrospun from sericin are biocompatible regardless of its molecular weight. The microparticles, not common in electrospinning of silk proteins reported previously, were found to promote the osteogenic differentiation of mesenchymal stem cells in comparison to the nanofibers. This study suggested that molecular weight of sericin mediates its secondary structure and assembly structure, which in turn leads to a control of final morphology of the electrospun materials. The microparticles and nanofibers of sericin can be potentially used as building blocks for fabricating the scaffolds for tissue engineering

Differential expression of human COMT alleles in brain and lymphoblasts detected by RT-coupled 5′ nuclease assay

A common polymorphism, Val158Met, alters catechol-O-methyltransferase (COMT) enzyme activity and has been linked to psychiatric phenotypes. Bray et al. (2003) reported that COMT is subject to differential allele expression in brain, finding modest (13–22%) underexpression of a haplotype containing Val158. However, disparate findings by another group who used the same method, but in lymphoblasts, raise the issues of tissue specificity, magnitude of differential expression, and identity of loci altering expression.We measured COMT allele expression ratios in heterozygous human lymphoblast cell lines and brains.Using transcribed single nucleotide polymorphisms as endogenous reporters, we developed an RT-coupled 5′ nuclease assay for allele expression ratios and applied it to 63 COMT rs4818(C>G) heterozygotes and 68 Val158Met [rs4680(G>A)] heterozygotes.For rs4818(C>G), the C allele was overexpressed relative to the G allele in 18 of 27 lymphoblast lines and 23 of 36 brains. For Val158Met, Met158 was overexpressed relative to Val158 in all (29 of 29) lymphoblast lines and all (39 of 39) brains. Each of the 22 rs4818 heterozygotes without differential allele expression was a Val158/Val158 homozygote. The Met158 allele was overexpressed by 65–77% when compared with Val158 in lymphoblasts and brain. Haplotype augmented ability to predict expression in brain only. However, the expression of the Val158 allele on the high-expressing haplotype was only 19% higher than Val158 alleles on the other haplotype background. COMT alleles are differentially expressed. The Met158 allele predicts higher mRNA expression in both brain and lymphoblasts. As exemplified here, the RT-coupled 5′ nuclease assay is a reliable method for the quantitative evaluation of cis-acting regulatory effects