Hitchhiking vesicular transport routes to the vacuole: Amyloid recruitment to the Insoluble Protein Deposit (IPOD)

Sequestration of aggregates into specialized deposition sites occurs in many species across all kingdoms of life ranging from bacteria to mammals and is commonly believed to have a cytoprotective function. Yeast cells possess at least 3 different spatially separated deposition sites, one of which is termed “Insoluble Protein Deposit (IPOD)” and harbors amyloid aggregates. We have recently discovered that recruitment of amyloid aggregates to the IPOD uses an actin cable based recruitment machinery that also involves vesicular transport.¹ Here we discuss how different proteins known to be involved in vesicular transport processes to the vacuole might act to guide amyloid aggregates to the IPOD. These factors include the Myosin V motor protein Myo2 involved in transporting vacuolar vesicles along actin cables, the transmembrane protein Atg9 involved in the recruitment of large precursor hydrolase complexes to the vacuole, the phosphatidylinositol/ phosphatidylcholine (PI/PC) transfer protein Sec 14 and the SNARE chaperone Sec 18. Furthermore, we present new data suggesting that the yeast dynamin homolog Vps1 is also crucial for faithful delivery of the amyloid model protein PrD-GFP to the IPOD. This is in agreement with a previously identified role for Vps1 in recruitment of heat-denatured aggregates to a perivacuolar deposition site.²

Preferential usage of TCR-Vbeta17 by peripheral and cutaneous T cells in nickel-induced contact dermatitis

Nickel (Ni) is one of the most common contact sensitizers in man, and Ni-induced contact dermatitis is considered as a model of hapten-induced delayed type hypersensitivity. Previous studies indicated that Ni-reactive T cells derived from Ni-allergic individuals preferentially express distinct TCR-Vbeta chains. However, data on the TCR-Vbeta repertoire of Ni-responsive T cells are not consistent. Therefore, the aim of this study was to identify the TCR-Vbeta receptors of Ni-responsive peripheral and cutaneous T cells in a cohort of 17 donors with Ni-induced contact dermatitis in comparison with those of 6 healthy controls. Peripheral NiSO(4)-responsive T lymphocytes showed a significant overexpression of TCR-Vbeta17 and the frequency of TCR-Vbeta17(+) T cells correlated significantly with the in vitro reactivity of PBMC to NiSO(4). In addition, the cutaneous infiltrate of Ni-induced patch test reactions consisted primarily of Vbeta17(+) T cells. The majority of patch test-derived NiSO(4)-responsive T cells of three allergic donors were TCR-Vbeta17(+), whereas patch test-derived NiSO(4) unresponsive T cells of four additional donors did not express TCR-Vbeta17. Skin-derived Ni-responsive T cell lines from three donors uniformly secreted the Th2 cytokine, IL-5, but no IFN-gamma or IL-10. These in vitro and in vivo findings strongly suggest that T cells with a restricted TCR-Vbeta repertoire, i.e., Vbeta17, predominate in NiSO(4)-induced contact dermatitis and may be crucial in the effector phase of Ni hypersensitivity.