Expression of the human β amyloid peptide (Aβ) in transgenic Caenorhabditis elegans animals can lead to the formation of intracellular immunoreactive deposits as well as the formation of intracellular amyloid. We have used this model to identify proteins that interact with intracellular Aβ in vivo . Mass spectrometry analysis of proteins that specifically coimmunoprecipitate with Aβ has identified six likely chaperone proteins: two members of the HSP70 family, three αB-crystallin-related small heat shock proteins (HSP-16s), and a putative ortholog of a mammalian small glutamine-rich tetratricopeptide repeat-containing protein proposed to regulate HSP70 function. Quantitative reverse transcription–PCR analysis shows that the small heat shock proteins are also transcriptionally induced by Aβ expression. Immunohistochemistry demonstrates that HSP-16 protein closely colocalizes with intracellular Aβ in this model. Transgenic animals expressing a nonaggregating Aβ variant, a single-chain Aβ dimer, show an altered pattern of coimmunoprecipitating proteins and an altered cellular distribution of HSP-16. Double-stranded RNA inhibition of R05F9.10, the putative C. elegans ortholog of the human small glutamine-rich tetratricopeptide-repeat-containing protein (SGT), results in suppression of toxicity associated with Aβ expression. These results suggest that chaperone function can play a role in modulating intracellular Aβ metabolism and toxicity.

Transgenic Caenorhabditis elegans animals have been engineered to express wild-type and singleamino acid variants of a long form of human /3-amyloid peptide (A/3 1-42). These animals express high levels (~3OOng of A/3/mg of total protein) of apparently fulllength peptide, as determined by quantitative immunoblot. Expression of wild-type Afi in these animals leads to rapid production of amyloid deposits reactive with Congo red and thioflavin S. This model system has been used to examine the effect of Leu 17Pro, Leu17Val, Ala30-Pro, Met35Cys, and Met35Leu substitutions on the in vivo production of amyloid deposits. We find that the Leu17 Pro and Met 35Cys substitutions completely block the formation of thioflavin S-reactive deposits, implicating these as key residues for in vivo amyloid formation. We have also constructed transgenic strains expressing a novel A/I variant, the single-chain dimer. Animals expressing high levels of this variant also fail to produce thioflavin S-reactive deposits. Key Words: Caenorhabditis elegans-Transgenic-/3-Amyloid peptide-/3-Amyloid peptide variant-Aggregation.

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Poster abstracts 58 els at E9.5; 54 genes, such as those encoding Bmp-1, IGF II and Sox3, were more highly expressed at E13.5; and another 126 genes, such as those encoding Mash 1, FHF-1 and fibulin-2, were expressed at higher levels at E16.5. The identification of these genes with highly stage-specific expression during craniofacial development is potentially important because they are likely to have key roles in the formation of craniofacial tissues. We are currently studying expression patterns of genes from an E8.5-9.5 mouse craniofacial cDNA library to identify novel craniofacial genes by microarray screening approaches.

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