hsp-4

1. 7-Dehydrocholesterol UV-B Vitamin D Slows Aging by Activation of the Endoplasmic Reticulum Unfolded Protein Response in C. elegans Karla Mark1, Dipa Bhaumik1, Milena Price1, Birgit Schilling1, Michael Holick2, Bradford W. Gibson1, Gordon J. Lithgow1 1Buck Institute for Research on Aging 2Boston University School of Medicine 2 -Control 8- Control 2 -D3 8 -D3 Previtamin D3 Lumisterol Tachysterol 2A. MW (KDa) Age of adulthood hsp-4 250 160 Cholecalciferol (D3) Food/Supplements 30 15 25-hydroxylase 3B. 25-hydroxyvitamin D Ergocalciferol(D2) 2B. 1A. 1-α-hydroxylase Figure 3A & 3B: The effect of D3 on the accumulation of insoluble protein in aged C. elegans. (A) D3 prevents the accumulation of SDS-insoluble proteins in aged worms. (B) Mass spectrometry quantification of proteins and peptides . 1,25-dihydroxy vitamin D (active form) 4. 2C. Introduction Vitamin D is a fat soluble secosteroid that comes in two major forms depending on the source, vitamin D2 (ergocalciferol) of plant origin, and vitamin D3 (cholecalciferol) of animal origin. Vitamin D2 (D2) is produced from ergosterol, in response to UV irradiation. Vitamin D3 (D3) is produced photochemically in the skin by action of UVB on 7-dehdrochloesterol. Vitamin D’s role in bone mineral homeostasis is well-known. Moreover, deficiencies in the circulating active form of this secosteriod has been now implicated in age-related chronic disease. The mechanism connecting vitamin D deficiency to chronic disease is unknown. Here we show that exposure of adult worms to D3 prevents the accumulation of a diverse range of insoluble proteins during aging and suppresses pathological features of metastable proteins and human β-amyloid-associated toxicity. Furthermore, D3 extends lifespan and selectively activates the endoplasmic reticulum unfolded protein response (ER UPR). Blocking the ER UPR prevents all the beneficial effects suggesting a novel mechanism of action. 3A. 5A. 5B. Figure 4: The effect of D3 on adult lifespan. D3 exposure dose-dependently extends lifespan of synchronously aging hermaphrodite wild-type (N2) population. Figure 2A,2B & 2C: The effect of D2 and D3 exposure on paralysis. D2 and D3 rescues the paralysis phenotype associated with protein aggregation in CL4176 (A) and HE250 (B) strains. (2C) Vitamin D metabolites prevent paralysis in CL4176 expressing Aβ(3-42). 0uM 50uM 5D. 5C. 5E. 5F. 1B. Bind to VDR Biologic actions Figure 5A-F: The effect of D3 on the ER unfolded protein response. (A) Fluorescent images of animals expressing the transcriptional reporter, hsp-4::GFP. (B) Quantification of GFP expression. D3 does not extend lifespan in ire-1 (C) and xbp-1 (E) mutants. RNAi of IRE-1 (D) and XBP-1 (F) prevents the D3-induced suppression of paralysis of metastableperlecan mutant. • Conclusions • D3 extends lifespan and decreases protein aggregation through a novel mechanism involving the IRE-1 ER Stress Pathway. • D3 may not only affect ER stress pathway but have an effect on a wider set of proteins as evidence by mass spectrometry data. Figure 1A & 1B: (A) Vitamin D biochemical pathway. (B) C. elegans convert vitamin D3 into a ligand that activates human VDR .