HIV-1 Nef Interacts with Inositol Trisphosphate Receptor to Activate Calcium Signaling in T Cells

HIV-1 pathogenicity factor Nef has been shown to modulate calcium signaling in host cells, but the underlying molecular mechanisms have remained unclear. Here we show that calcium/calcineurin-dependent activation of nuclear factor of activated T cells (NFAT) by Nef in Jurkat T cells requires the endoplasmic reticulum-resident inositol trisphosphate receptor (IP3R), but yet does not involve increase in phospholipase-Cγ1 (PLCγ1)-catalyzed production of IP3 or depletion of IP3-regulated intracellular calcium stores. Nef could be coprecipitated with endogenous IP3R type-1 (IP3R1) from Nef-transfected Jurkat T cells as well as from HIV-infected primary human peripheral mononuclear cells. Thus, the Nef/IP3R1-interaction defines a novel T cell receptor–independent mechanism by which Nef can promote T cell activation, and appears to involve atypical IP3R-triggered activation of plasma membrane calcium influx channels in a manner that is uncoupled from depletion of intracellular calcium stores

Deep convolutional neural networks and digital holographic microscopy for in-focus depth estimation of microscopic objects

Deep artificial neural network learning is an emerging tool in image analysis. We demonstrate its poten- tial in the field of digital holographic microscopy by addressing the challenging problem of determining the in-focus reconstruction depth of an arbitrary epithelial cell cluster encoded in a digital hologram. A deep convolutional neural network learns the in-focus depths from half a million hologram amplitude images. The trained network correctly determines the in-focus depth of new holograms with high probability, with- out performing numerical propagation. To our knowledge, this is the first application of deep learning in the field of digital holographic microscopy

FAPP2 is involved in the transport of apical cargo in polarized MDCK cells

Phosphatidylinositol-4-phosphate (PI(4)P) is the main phosphoinositide in the Golgi complex and has been reported to play a pleiotropic role in transport of cargo from the trans-Golgi network to the plasma membrane (PM) in polarized Madin–Darby canine kidney (MDCK) cells. Overexpression of the chimeric fluorescent protein encoding the pleckstrin homology domain, which is specific for PI(4)P, inhibited both apical and basolateral transport pathways. The transport of apical cargo from the Golgi was shown to be specifically decreased by adenovirus-mediated RNA interference directed against PI(4)P adaptor protein (FAPP) 2. FAPP1 depletion had no effect on transport. On the other hand, FAPP2 was not involved in the Golgi-to-PM transport of cargo that was targeted to the basolateral membrane domain. Thus, we conclude that FAPP2 plays a specific role in apical transport in MDCK cells

Altered glycosylation of several metastasis-associated glycoproteins with terminal GalNAc defines the highly invasive cancer cell phenotype

Publisher Copyright: © 2022 Khosrowabadi et al.Several distinct metastasis-associated glycosylation changes have been shown to promote cancer cell invasion and metastasis, the main cause of death of cancer patients. However, it is unclear whether their presence reflects cell- or tissue-specific variations for metastasis, or species needed to drive different phases of the metastatic cascade. To address this issue from a different perspective, we investigated here whether different cancer cell lines share any glycotopes that are common and important for their invasive phenotype. By using lectin microarray glycan profiling and an established myoma tissue-based 3D invasion assay, we identified a single glycotope recognized by Helix Pomatia agglutinin (HPA), whose expression level in different cancer cells correlated significantly with their invasive potential. Lectin pull-down assay and LC-MS/MS analysis in highly- (A431 and SW-48) and poorly invasive (HepG2 and RCC4) cancer cells revealed ~85 glycoproteins of which several metastasis-promoting members of the integrin family of cell adhesion receptors, the epidermal growth factor receptor (EGFR) and the matrix metalloproteinase-14 (MMP-14) were among the abundant ones. Moreover, we showed that the level of the GalNAc glycotope in MMP-14, EGFR, αV-, β1- and β4 integrin in highly and poorly invasive cancer cells correlated positively with their invasive potential. Collectively, our findings suggest that altered glycosylation of several metastasis-associated glycoproteins with terminal GalNAc drives the highly invasive cancer cell phenotype.Peer reviewe

Monitoring MDCK cell vesicles by digital holographic microscopy and image processing

Digital holographic microscopy and image processing is used to track vesicles of Madin Darby canine kidney cells. Multiple-depth amplitude reconstructions are used as the basis for tracking. Individual vesicle movement in three dimensions is shown

Temporal Deep Learning Classification of Digital Hologram Reconstructions of Multicellular Samples

Digital holographic microscopy allows label-free capture of the full wavefront of light from an object using a low intensity laser. Using numerical reconstructions as an input to deep convolutional neural networks, detection of tumorigenic samples is feasible

Detecting the presence of a transparent object in off-axis digital holograms

Detecting presence of an object in digital holograms is an important consideration in many applications. We propose a novel method that works directly in the hologram plane to determine the presence or absence of an object

Assembly of the beta 4-Integrin Interactome Based on Proximal Biotinylation in the Presence and Absence of Heterodimerization

Integrin-mediated laminin adhesions mediate epithelial cell anchorage to basement membranes and are critical regulators of epithelial cell polarity. Integrins assemble large multiprotein complexes that link to the cytoskeleton and convey signals into the cells. Comprehensive proteomic analyses of actin network-linked focal adhesions (FA) have been performed, but the molecular composition of intermediate filament-linked hemidesmosomes (HD) remains incompletely characterized. Here we have used proximity-dependent biotin identification (BioID) technology to label and characterize the interactome of epithelia-specific beta 4-integrin that, as alpha 6 beta 4-heterodimer, forms the core of HDs. The analysis identified similar to 150 proteins that were specifically labeled by BirA-tagged integrin-beta 4. In addition to known HDs proteins, the interactome revealed proteins that may indirectly link integrin-beta 4 to actin-connected protein complexes, such as FAs and dystrophin/dystroglycan complexes. The specificity of the screening approach was validated by confirming the HD localization of two candidate beta 4-interacting proteins, utrophin (UTRN) and ELKS/Rab6-interacting/CAST family member 1 (ERC1). Interestingly, although establishment of functional HDs depends on the formation of alpha 6 beta 4-heterodimers, the assembly of beta 4-interactome was not strictly dependent on alpha 6-integrin expression. Our survey to the HD interactome sets a precedent for future studies and provides novel insight into the mechanisms of HD assembly and function of the beta 4-integrin.Peer reviewe