Biology subjects

Vashisht, A. A.

Publications and source records attributed to Vashisht, A. A..

3 recordsLinked to original sources

bioRxiv2022

The metabolite alpha-ketobutyrate increases health and life spans by activating AMPK

Aging is a complex process that is directly related to human health and disease. The extraordinary finding that aging is malleable, as shown in model organisms whose life and health spans are extended by specific gene mutations or dietary or pharmacological perturbations 1-3, has offered enormous hope for our understanding and treatment of aging and related diseases. Although many molecules have been identified that can extend the lifespan of model organisms, few have been shown to alleviate age-related symptoms or illness in mammals 4. Here we show that supplementation with the endogenous metabolite -ketobutyrate (-KB) increases the lifespan of adult C. elegans. Using Gelfree DARTS-PROTOMAP, we identified microtubule-actin cross-linking factor (MACF1) that was protected against proteolysis in the presence of -KB. MACF1 belongs to the spectraplakin family of giant, evolutionarily conserved proteins with versatile functions 5, but their link to longevity regulation has not been explored. -KBs longevity effect in C. elegans is abrogated by loss-of-function mutation in vab-10, encoding the worm ortholog of mammalian MACF1 6. Like -KB treatment, vab-10 knockdown activates AMP-activated protein kinase (AMPK), and AMPK is required for -KB effects on longevity. The findings suggest a model in which -KB increases longevity by activating AMPK via VAB-10/MACF1 modulation. -KB also delays aging in mammals, increasing the lifespan of aged male mice and the healthspan of both male and female animals. Targeting of broadly expressed scaffolding proteins in connection to cellular energy homeostasis seems to be a clever way that nature has devised for metabolite signals to impinge upon multiple organ and tissue systems, which may have utility for controlling aging and related diseases.

physiology↗

bioRxiv2022

Drug interaction mapping with proximity dependent enzyme recruiting chimeras

Proximity dependent labeling using engineered enzymes has been used extensively to identify protein-protein interactions, and map protein complexes in-vitro and in-vivo. Here, we extend the use of engineered promiscuous biotin ligases to the identification of small molecule protein targets. Chimeric bi-functional chemical probes ("recruiters") are used to effectively recruit tagged biotin ligases for proximity dependent labeling of target and target interactors. The broad applicability of this approach is demonstrated with probes developed from a multi-kinase inhibitor, a bromodomain targeting moiety, and an FKBP targeting molecule. While complementary to traditional chemo-proteomic strategies such as photo-affinity labeling (PAL), and activity-based protein profiling (ABPP), this approach is a useful addition to the target ID toolbox with opportunities for tunability based on the inherent labeling efficiencies of different engineered enzymes and control over the enzyme cellular localization.

molecular biology↗

bioRxiv2017

Regulation Of Iron Homeostasis By SPAK-Dependent Modulation Of FBXL5 Stability

Intracellular iron homeostasis is regulated by a proteolytic switch whereby the E3 ubiquitin ligase FBXL5 targets iron regulatory proteins (IRPs) for ubiquitin-dependent degradation in iron-replete conditions while it is itself degraded during iron deficiency allowing IRPs to accumulate and regulate their downstream RNA targets. The cellular pathways that control FBXL5 degradation in low iron conditions are not well understood. Here, we report the identification of the STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) as a novel regulator of FBXL5 stability. We find that SPAK, a kinase previously implicated in osmotic stress regulation, regulates intracellular iron homeostasis through its physical association with FBXL5. This role is dependent on its kinase activity as overexpression of constitutively active SPAK increases FBXL5 poly-ubiquitination and degradation. Through this work, we have discovered a novel role for SPAK that extends beyond its well-established function in salt homeostasis and raises the possibility for signaling crosstalk between iron homeostatic and osmotic regulatory pathways.

biochemistry↗