Ting Zhang | Search bioRxiv

bioRxiv2020

Metabolic features of mouse and human retinas: rods vs. cones, macula vs. periphery, retina vs. RPE

Photoreceptors, especially cones, which are enriched in the human macula, have high energy demands, making them vulnerable to metabolic stress. Metabolic dysfunction of photoreceptors and their supporting retinal pigment epithelium (RPE) is an important underlying cause of degenerative retinal diseases. However, how cones and the macula support their exorbitant metabolic demand and communicate with RPE is unclear. By profiling metabolite uptake and release and analyzing metabolic genes, we have found cone-rich retinas and human macula share specific metabolic features with upregulated pathways in pyruvate metabolism, mitochondrial TCA cycle and lipid synthesis. Human neural retina and RPE have distinct but complementary metabolic features. Retinal metabolism centers on NADH production and neurotransmitter biosynthesis. The retina needs aspartate to sustain its aerobic glycolysis and mitochondrial metabolism. RPE metabolism is directed toward NADPH production and biosynthesis of acetyl-rich metabolites, serine and others. RPE consumes multiple nutrients, including proline, to produce metabolites for the retina.

neuroscience↗

bioRxiv2020

Kindlin2-mediated phase separation underlies integrin adhesion formation

Formation of cell-extracellular matrix adhesion requires assembly of the transmembrane receptor integrins and their intracellular activators, kindlin and talin proteins in minutes. The mechanisms governing the rapid formation and dynamics of the adhesion remain enigmatic. Here, we reported that the dimerized-kindlin2 underwent phase separation with clustered-integrin in solution and on lipid bilayer. The kindlin2/integrin condensate can further enrich other components for the adhesion complex assembly. The full-length structure of kindlin2 was solved and revealed that the kindlin2 dimers can further pack with each other to form a higher oligomer. Disrupting the intermolecular interaction between the kindlin2 dimer inhibits the phase formation on 2D membrane in vitro and impaired the adhesion formation, integrin activation, and cell spreading in cultured cells. We also determined the full-length structure of kindlin2 in its monomeric conformation. Structural analysis and biochemical characterization indicate that the interdomain interaction control the monomer-dimer transition of kindlin2, providing a regulation mechanism of the kindlin2-mediated phase separation. Our findings not only provide a mechanistic explanation for the formation and dynamic regulation of the integrin-based adhesion, but also shed light on understanding of how the clustered receptors participate in assembly of the functional membrane domains via phase separation.

biochemistry↗