RESUMEN
Hemizygous deletion of chromosome 22q11 (del22q11) causes thymic, parathyroid, craniofacial and life-threatening cardiovascular birth defects in 1 in 4,000 infants. The del22q11 syndrome is likely caused by haploinsufficiency of TBX1, but its variable expressivity indicates the involvement of additional modifiers. Here, we report that absence of the Vegf164 isoform caused birth defects in mice, reminiscent of those found in del22q11 patients. The close correlation of birth and vascular defects indicated that vascular dysgenesis may pathogenetically contribute to the birth defects. Vegf interacted with Tbx1, as Tbx1 expression was reduced in Vegf164-deficient embryos and knocked-down vegf levels enhanced the pharyngeal arch artery defects induced by tbx1 knockdown in zebrafish. Moreover, initial evidence suggested that a VEGF promoter haplotype was associated with an increased risk for cardiovascular birth defects in del22q11 individuals. These genetic data in mouse, fish and human indicate that VEGF is a modifier of cardiovascular birth defects in the del22q11 syndrome.
Asunto(s)
Deleción Cromosómica , Síndrome de DiGeorge/genética , Factores de Crecimiento Endotelial/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Linfocinas/genética , Animales , Vasos Sanguíneos/anomalías , Anomalías Congénitas/genética , Cara/anomalías , Ratones , Ratones Noqueados , Neuropilina-1/genética , Isoformas de Proteínas/genética , Cráneo/anomalías , Proteínas de Dominio T Box/genética , Timo/anomalías , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial Vascular , Pez CebraRESUMEN
The biological function of prion protein (PrP) and the physiological relevance of its truncated subtypes and glycoforms is still enigmatic. In this paper, we adduce evidence that recombinant murine PrP fragment 90-231 (mPrP90-231) contains a biotin-mimicking sequence motif that causes binding of the bacterial protein streptavidin to mPrP90-231. As indicated by epitope mapping and proven by analysis of a deletion mutant (mPrP101-231), streptavidin binding is primarily mediated by the amino-terminus of mPrP90-231 with the core-binding sequence represented by residues 94-100. Competition with biotin significantly reduces the interaction pointing to an involvement of streptavidin's biotin-binding site (BBS). Since the BBS of streptavidin shares similarities with the active sites of proteins involved in biotin metabolism we speculate that biotin mimicry by truncated PrP-species may have an impact in vivo.
Asunto(s)
Priones/química , Precursores de Proteínas/química , Estreptavidina/química , Secuencias de Aminoácidos , Animales , Sitios de Unión , Biotina/química , Epítopos/química , Eliminación de Gen , Indicadores y Reactivos/química , Ratones , Mutación , Proteínas Priónicas , Unión Proteica , Estructura Terciaria de Proteína , Proteínas Recombinantes/químicaRESUMEN
To test whether prion protein (PrP) specific secretory immunoglobulin A (sIgA) can be induced and protect against oral transmission of spongiform encephalopathy (SE) we immunized Balb/c mice either intragastrically or intranasally (i.n.) with a recombinant PrP-fragment (PrP90-231) and cholera toxin (CT) adjuvant. Since PrP90-231 was rapidly digested in intestinal lavage, aprotinin was added to some vaccine formulations. While an anti-CT response was elicited via both routes, solely i.n. immunization without aprotinin induced PrP-specific sIgA. They recognize predominantly PrP-oligomers as the antigen was aggregated in the vaccine formulations. Challenge experiments showed that the immune response induced by our protocol could not prevent disease, but increases the median survival of the animals. We conclude that PrP-specific sIgA reduce the infectivity of the inoculum and that complete protection against transmission of SE should be achievable by optimized immunization regimens.