SALL4 has recently been identified to promote chemo-resistance in multiple types of cancer, but the underlying mechanism remains to be fully established. Open chromatin structure is important for DNA damage response (DDR) and DNA repair. Here, we demonstrate that SALL4 promotes open chromatin by destabilizing heterochromatin protein 1α (HP1α) by recruiting ubiquitin E3 ligase CUL4B to HP1α. The silencing of SALL4 in cancer cells decreased the expression levels of Glut1 and inhibited glycolysis in cancer cells. The upregulation of HP1α in human cancer cells suppressed open chromatin, glycolysis and Glut1 expression levels. Therefore, SALL4 promotes the expression of Glut1 and open chromatin through a HP1α-dependent mechanism. Impaired DDR in SALL4-deficient human cancer cells can be rescued by the restored expression of Glut1, indicating the importance of HP1α-Glut1 axis in SALL4-mediated DDR. These findings demonstrate that SALL4 could induce drug resistance by enhancing DDR and DNA repair through promoting glycolysis and subsequent chromatin remodeling.

Graphene is an atomically thin plasmonic medium that supports highly confined plasmon polaritons, or nano-light, with very low loss. Electronic properties of graphene can be drastically altered when it is laid upon another graphene layer, resulting in a moiré superlattice. The relative twist angle between the two layers is a key tuning parameter of the interlayer coupling in thus-obtained twisted bilayer graphene (TBG). We studied the propagation of plasmon polaritons in TBG by infrared nano-imaging. We discovered that the atomic reconstruction occurring at small twist angles transforms the TBG into a natural plasmon photonic crystal for propagating nano-light. This discovery points to a pathway for controlling nano-light by exploiting quantum properties of graphene and other atomically layered van der Waals materials, eliminating the need for arduous top-down nanofabrication.

Plasmon polaritons are hybrid excitations of light and mobile electrons that can confine the energy of long-wavelength radiation at the nanoscale. Plasmon polaritons may enable many enigmatic quantum effects, including lasing ¹ , topological protection^2,3 and dipole-forbidden absorption ⁴ . A necessary condition for realizing such phenomena is a long plasmonic lifetime, which is notoriously difficult to achieve for highly confined modes ⁵ . Plasmon polaritons in graphene-hybrids of Dirac quasiparticles and infrared photons-provide a platform for exploring light-matter interaction at the nanoscale^6,7. However, plasmonic dissipation in graphene is substantial ⁸ and its fundamental limits remain undetermined. Here we use nanometre-scale infrared imaging to investigate propagating plasmon polaritons in high-mobility encapsulated graphene at cryogenic temperatures. In this regime, the propagation of plasmon polaritons is primarily restricted by the dielectric losses of the encapsulated layers, with a minor contribution from electron-phonon interactions. At liquid-nitrogen temperatures, the intrinsic plasmonic propagation length can exceed 10 micrometres, or 50 plasmonic wavelengths, thus setting a record for highly confined and tunable polariton modes. Our nanoscale imaging results reveal the physics of plasmonic dissipation and will be instrumental in mitigating such losses in heterostructure engineering applications.

Photonic crystals are commonly implemented in media with periodically varying optical properties. Photonic crystals enable exquisite control of light propagation in integrated optical circuits, and also emulate advanced physical concepts. However, common photonic crystals are unfit for in-operando on/off controls. We overcome this limitation and demonstrate a broadly tunable two-dimensional photonic crystal for surface plasmon polaritons. Our platform consists of a continuous graphene monolayer integrated in a back-gated platform with nano-structured gate insulators. Infrared nano-imaging reveals the formation of a photonic bandgap and strong modulation of the local plasmonic density of states that can be turned on/off or gradually tuned by the applied gate voltage. We also implement an artificial domain wall which supports highly confined one-dimensional plasmonic modes. Our electrostatically-tunable photonic crystals are derived from standard metal oxide semiconductor field effect transistor technology and pave a way for practical on-chip light manipulation.