PHLPP1 regulates CFTR activity and lumen expansion through AMPK.

Complex organ development depends on single lumen formation and its expansion during tubulogenesis. This can be achieved by correct mitotic spindle orientation during cell division, combined with luminal fluid filling that generates hydrostatic pressure. Using a human 3D cell culture model, we have identified two regulators of these processes. We find that pleckstrin homology leucine-rich repeat protein phosphatase (PHLPP) 2 regulates mitotic spindle orientation, and thereby midbody positioning and maintenance of a single lumen. Silencing the sole PHLPP family phosphatase in Drosophila melanogaster, phlpp, resulted in defective spindle orientation in Drosophila neuroblasts. Importantly, cystic fibrosis transmembrane conductance regulator (CFTR) is the main channel regulating fluid transport in this system, stimulated by phosphorylation by protein kinase A and inhibited by the AMP-activated protein kinase AMPK. During lumen expansion, CFTR remains open through the action of PHLPP1, which stops activated AMPK from inhibiting ion transport through CFTR. In the absence of PHLPP1, the restraint on AMPK activity is lost and this tips the balance in the favour of channel closing, resulting in the lack of lumen expansion and accumulation of mucus.

Super-resolution re-scan second harmonic generation microscopy.

Second harmonic generation microscopy (SHG) is generally acknowledged as a powerful tool for the label-free three-dimensional visualization of tissues and advanced materials, with one of its most popular applications being collagen imaging. Despite the great need, progress in super-resolved SHG imaging lags behind the developments reported over the past years in fluorescence-based optical nanoscopy. In this work, we demonstrate super-resolved re-scan SHG, qualitatively and quantitatively showing on collagenous tissues the available resolution advantage over the diffraction limit. We introduce as well super-resolved re-scan two-photon excited fluorescence microscopy, an imaging modality not explored to date.

Multifunctional Modulation of High-Performance Znx Fe3-x O4 Nanoparticles by Precisely Tuning the Zinc Doping Content.

The possibility to precisely control important properties of nanoparticles (NPs) such as their size, morphology, surface charge, or doping content is crucial for enhancing the performance of existing solutions beyond the state-of-the-art and for enabling novel applications. In this work, custom-tailored Znx Fe3- x O4 NPs are synthesized at different Zn doping concentrations to augment and expand their usefulness for high-performance applications in nanomedicine. By precisely increasing the Zn2+ content in the range of 0 ≤ x ≤ 2.0, the discussed NPs can sequentially acquire valuable properties enabling magnetic resonance imaging, near-infrared (NIR) photothermal effects, NIR photocatalytic and photoelectric effects, depending on the variation of substitution position of the Zn2+ in the magnetite structure and the emergence of a ZnO/ZnFe2 O4 heterostructure at high doping concentrations. The presented work demonstrates and explainsa facile route for the synthesis and modulation of multifunctional nanomaterials with manifold roles in disease diagnostics and therapy, and provides helpful guidance in designing divalent transition metal ion-doped nanomaterials.

"Double-punch" strategy against triple-negative breast cancer via a synergistic therapy of magneto-mechanical force enhancing NIR-II hypothermal ablation.

Triple-negative breast cancer (TNBC) is a form of breast cancer that is more aggressive and harder to treat than others, with a higher probability of relapse. Its nefarious capabilities for migrating and invading other parts of the body together with the current lack of clinically established effective therapies account for a low survival rate. In this work, we demonstrate the in-tandem use of two complementary therapeutic routes to effectively combat TNBC. A versatile magnetic-photothermal converter (MPC) consisting of zinc-doped ferrite nanoparticles and polyethene glycol, is shown to display excellent therapeutic efficiency, being capable to fight TNBC via two distinct routes: magneto-mechanical force (MMF) and near-infrared-II (NIR-II) hypothermal ablation. The combined use of these two complementary and synergistic therapies, which are less aggressive to the human body compared to conventional chemotherapeutic approaches, results in the splendid suppression of TNBC migration and invasion. Remotely controlling the MPCs by an external magnetic field, results in cellular MMF effects that cause direct mechanical destruction to the cancer cell membrane, leading to its necrosis. Furthermore, the MMF disrupts intracellular lysosomes, thereby triggering the release of large amounts of protein hydrolases, which induce intracellular oxidative stress, and accelerate the induction of apoptosis. Complementing the therapeutic approach based on MMF, the excellent photothermal performance of the MPC in the NIR-II region (1064 nm) is exploited to enable effective hypothermal ablation of the tumours, which can be achieved in deep tissue layers. The proposed multifunctional nanocomposites, together with the demonstrated "double-punch" therapeutic approach, hold significant potential to pave the way for future cutting-edge weapons against the dreadful TNBC.

Scattering-type Scanning Near-Field Optical Microscopy of Polymer-Coated Gold Nanoparticles.

Scattering-type scanning near-field optical microscopy (s-SNOM) has emerged over the past years as a powerful characterization tool that can probe important properties of advanced materials and biological samples in a label-free manner, with spatial resolutions lying in the nanoscale realm. In this work, we explore such usefulness in relationship with an interesting class of materials: polymer-coated gold nanoparticles (NPs). As thoroughly discussed in recent works, the interplay between the Au core and the polymeric shell has been found to be important in many applications devoted to biomedicine. We investigate bare Au NPs next to polystyrenesulfonate (PSS) and poly(diallyldimethylammonium chloride) (PDDA) coated ones under 532 nm laser excitation, an wavelength matching the surface plasmon band of the custom-synthesized nanoparticles. We observe consistent s-SNOM phase signals in the case of bare and shallow-coated Au NPs, whereas for thicker shell instances, these signals fade. For all investigated samples, the s-SNOM amplitude signals were found to be very weak, which may be related to reduced scattering efficiency due to absorption of the incident beam. We consider these observations important, as they may facilitate studies and applications in nanomedicine and nanotechnology where the precise positioning of polymer-coated Au NPs with nanoscale resolution is needed besides their dielectric function and related intrinsic optical properties, which are also quantitatively available with s-SNOM.

Plasma membrane damage causes NLRP3 activation and pyroptosis during Mycobacterium tuberculosis infection.

Mycobacterium tuberculosis is a global health problem in part as a result of extensive cytotoxicity caused by the infection. Here, we show how M. tuberculosis causes caspase-1/NLRP3/gasdermin D-mediated pyroptosis of human monocytes and macrophages. A type VII secretion system (ESX-1) mediated, contact-induced plasma membrane damage response occurs during phagocytosis of bacteria. Alternatively, this can occur from the cytosolic side of the plasma membrane after phagosomal rupture in infected macrophages. This damage causes K+ efflux and activation of NLRP3-dependent IL-1ß release and pyroptosis, facilitating the spread of bacteria to neighbouring cells. A dynamic interplay of pyroptosis with ESCRT-mediated plasma membrane repair also occurs. This dual plasma membrane damage seems to be a common mechanism for NLRP3 activators that function through lysosomal damage.