Biology subjects

Jiao, J.

Publications and source records attributed to Jiao, J..

22 records · Page 2Linked to original sources

bioRxiv2019

TRIM21 and PHLDA3 Negatively Regulate the Cross-Talk between the PI3K/AKT Pathway and PPP Metabolism

PI3K/AKT signaling is known to regulate cancer metabolism but whether metabolic pathway feedbacks and regulates the PI3K/AKT pathway is unclear. Here, we demonstrate the important reciprocal cross-talks between the PI3K/AKT signal and PPP branching metabolic pathways. PI3K/AKT activation stabilizes G6PD, the rate-limiting enzyme of PPP, by inhibiting a newly identified E3 ligase TIRM21, and promotes PPP. PPP metabolites, in turn, reinforce AKT activation and further promote cancer metabolic reprogramming by blocking the expression of an AKT inhibitor PHLDA3. Knockout TRIM21 or PHLDA3 promotes the cross-talks and cell proliferation. Importantly, PTEN null human cancer cells and in vivo murine models are sensitive to anti-PPP treatments, suggesting the importance of PPP in maintaining AKT activation even in the presence of a constitutively activated PI3K pathway. Our study suggests that blockade of these reciprocal cross-talks may have a therapeutic benefit for cancers with PTEN loss or PI3K/AKT activation.

cancer biology↗

bioRxiv2018

Munc18-1 catalyzes neuronal SNARE assembly by templating SNARE association

Sec1/Munc18-family (SM) proteins are required for SNARE-mediated membrane fusion, but their mechanism(s) of action remain controversial. Using single-molecule force spectroscopy, we found that the SM protein Munc18-1 catalyzes step-wise zippering of three synaptic SNAREs (syntaxin, VAMP2, and SNAP-25) into a four-helix bundle. Catalysis requires formation of an intermediate template complex in which Munc18-1 juxtaposes the N-terminal regions of the SNARE motifs of syntaxin and VAMP2, while keeping their C-terminal regions separated. Next, SNAP-25 binds the templated SNAREs to form a partially-zippered SNARE complex. Finally, full zippering displaces Munc18-1. Munc18-1 mutations modulate the stability of the template complex in a manner consistent with their effects on membrane fusion, indicating that chaperoned SNARE assembly is essential for exocytosis. Two other SM proteins, Munc18-3 and Vps33, similarly chaperone SNARE assembly via a template complex, suggesting that SM protein mechanism is conserved.

biophysics↗

bioRxiv2018

Hair regeneration by small molecules that activate autophagy

Hair plays important roles, ranging from the conservation of body heat to the preservation of psychological well-being. Hair loss or alopecia affects millions worldwide and can occur because of aging, hormonal dysfunction, autoimmunity, or as a side effect of cancer treatment (Gilhar et al., 2012; Petukhova et al., 2010). Methods that can be used to regrow hair are highly sought after, but lacking. Here we report that hair regeneration can be stimulated by small molecules that activate autophagy, including the longevity metabolites -ketoglutarate and -ketobutyrate, and the prescription drugs rapamycin and metformin which impinge on TOR and AMPK signaling.

developmental biology↗

bioRxiv2017

Single-molecule force spectroscopy of protein-membrane interactions

Many biological processes rely on protein-membrane interactions in the presence of mechanical forces, yet high resolution methods to quantify such interactions are lacking. Here, we describe a single-molecule force spectroscopy approach to quantify membrane binding of C2 domains in Synaptotagmin-1 (Syt1) and Extended Synaptotagmin-2 (E-Syt2). Syts and E-Syts bind the plasma membrane via multiple C2 domains, bridging the plasma membrane with synaptic vesicles or endoplasmic reticulum to regulate membrane fusion or lipid exchange, respectively. In our approach single proteins attached to membranes supported on silica beads are pulled by optical tweezers, allowing membrane binding and unbinding transitions to be measured with unprecedented spatiotemporal resolution. C2 domains from either protein resisted unbinding forces of 2-7 pN and had binding energies of 4-14 kBT per C2 domain. Regulation by bilayer composition or Ca2+ recapitulated known properties of both proteins. The method can be widely applied to study protein-membrane interactions.

biophysics↗