Vitorica, J. | bioRxiv Science

bioRxiv2019

Steroid hormones sulfatase inactivation extends lifespan and ameliorates age-related diseases

Aging and fertility are two interconnected processes. From invertebrates to mammals, absence of the germline increases longevity by a still not fully understood mechanism. We find that loss of function of sul-2, the Caenorhabditis elegans steroid sulfatase (STS), raises the pool of sulfated steroid hormones and increases longevity. This increased longevity requires factors involved in germline-mediated longevity (daf-16, daf-12, kri-1, tcer-1 and daf-36 genes) and is not additive to the longevity of germline-less mutants. Noteworthy, sul-2 mutations do not affect fertility. Thus, STS inactivation affects the germline signalling process regulating longevity. Interestingly, sul-2 is only expressed in sensory neurons, suggesting a regulation of germline longevity by environmental cues. We also demonstrate that treatment with the specific STS inhibitor STX64, reproduces the longevity phenotype of sul-2 mutants. Remarkably, STS inhibition by either mutation or drug treatment ameliorates protein aggregation diseases in C. elegans models of Parkinson, Huntington and Alzheimer, as well as Alzheimer disease in a mammalian model. These results open the possibility of reallocating steroid sulfatase inhibitors for the treatment of aging and aging related diseases.

developmental biology↗

bioRxiv2018

Galectin-3, A Novel Endogenous Trem2 Ligand, Regulates Inflammatory Response and Aβ Fibrilation in Alzheimer’s Disease

Alzheimers disease (AD) is a progressive neurodegenerative disease in which the formation of extracellular aggregates of amyloid beta (A{beta}) peptide, intraneuronal tau neurofibrillary tangles and microglial activation are major pathological hallmarks. One of the key molecules involved in microglial activation is galectin-3 (gal3), and we demonstrate here for the first time a key role of gal3 in AD pathology. Gal3 was highly upregulated in the brains of AD patients and 5xFAD (familial Alzheimers disease) mice, and found specifically expressed in microglia associated with A{beta} plaques. Single nucleotide polymorphisms in the LGALS3 gene, which encodes gal3, were associated to an increased risk of AD. Gal3 deletion in 5xFAD mice attenuated microglia-associated immune responses, particularly those associated with TLR and TREM2/DAP12 signaling. In vitro data demonstrated the requirement of gal3 to fully activate microglia in response to fibrillar A{beta}. Gal3 deletion decreased the A{beta} burden in 5xFAD mice and improved cognitive behavior. Electron microscopy of gal3 in AD mice demonstrated i) a preferential expression of gal3 by plaque-associated microglia, ii) its presence in the extracellular space and iii) its association to A{beta} plaques. Low concentrations (1 nM) of pure gal3 promoted cross-seeding fibrilization of pure A{beta}. Importantly, a single intrahippocampal injection of gal3 along with A{beta} monomers in WT mice was sufficient to induce the formation of insoluble A{beta} aggregates that were absent when gal3 was lacking. High-resolution microscopy (STORM) demonstrated close co-localization of gal3 and TREM2 in microglial processes, and a direct interaction was shown by a fluorescence anisotropy assay involving the gal3 CRD domain. Furthermore, gal3 stimulated the TREM2-DAP12 signaling pathway. In conclusion, we provide evidence that gal3 is a central regulator of microglial immune response in AD. It drives proinflammatory activation and A{beta} aggregation, as well as acting as an endogenous ligand to TREM2, a key receptor driving microglial response under disease conditions. Gal3 inhibition may, hence, be a potential pharmacological approach to counteract AD.

neuroscience↗