Mono- and Biallelic Protein-Truncating Variants in Alpha-Actinin 2 Cause Cardiomyopathy Through Distinct Mechanisms.

Background: ACTN2 (alpha-actinin 2) anchors actin within cardiac sarcomeres. The mechanisms linking mutations to myocardial disease phenotypes are unknown. Here, we characterize patients with novel mutations to reveal insights into the physiological function of ACTN2.

COUNTEN, an AI-Driven Tool for Rapid and Objective Structural Analyses of the Enteric Nervous System.

The enteric nervous system (ENS) consists of an interconnected meshwork of neurons and glia residing within the wall of the gastrointestinal (GI) tract. While healthy GI function is associated with healthy ENS structure, defined by the normal distribution of neurons within ganglia of the ENS, a comprehensive understanding of normal neuronal distribution and ganglionic organization in the ENS is lacking. Current methodologies for manual enumeration of neurons parse only limited tissue regions and are prone to error, subjective bias, and peer-to-peer discordance.

Electrical and synaptic integration of glioma into neural circuits.

High-grade gliomas are lethal brain cancers whose progression is robustly regulated by neuronal activity. Activity-regulated release of growth factors promotes glioma growth, but this alone is insufficient to explain the effect that neuronal activity exerts on glioma progression. Here we show that neuron and glioma interactions include electrochemical communication through bona fide AMPA receptor-dependent neuron-glioma synapses.

G-Protein Gα Functions with Abl Kinase to Regulate Actin Cytoskeletal Reorganization.

Heterotrimeric G-proteins are essential cellular signal transducers. One of the G-proteins, Gα, is critical for actin cytoskeletal reorganization, cell migration, cell proliferation, and apoptosis. Previously, we have shown that Gα is essential for both G-protein-coupled receptor and receptor tyrosine kinase-induced actin cytoskeletal reorganization such as dynamic dorsal ruffle turnover and cell migration.

Automatic detection of diffusion modes within biological membranes using back-propagation neural network.

Background: Single particle tracking (SPT) is nowadays one of the most popular technique to probe spatio-temporal dynamics of proteins diffusing within the plasma membrane. Indeed membrane components of eukaryotic cells are very dynamic molecules and can diffuse according to different motion modes. Trajectories are often reconstructed frame-by-frame and dynamic properties often evaluated using mean square displacement (MSD) analysis.

KIF17 regulates RhoA-dependent actin remodeling at epithelial cell-cell adhesions.

The kinesin KIF17 localizes at microtubule plus-ends where it contributes to regulation of microtubule stabilization and epithelial polarization. We now show that KIF17 localizes at cell-cell adhesions and that KIF17 depletion inhibits accumulation of actin at the apical pole of cells grown in 3D organotypic cultures and alters the distribution of actin and E-cadherin in cells cultured in 2D on solid supports. Overexpression of full-length KIF17 constructs or truncation mutants containing the N-terminal motor domain resulted in accumulation of newly incorporated GFP-actin into junctional actin foci, cleared E-cadherin from cytoplasmic vesicles and stabilized cell-cell adhesions to challenge with calcium depletion.

A biosensor of local kinesin activity reveals roles of PKC and EB1 in KIF17 activation.

We showed previously that the kinesin-2 motor KIF17 regulates microtubule (MT) dynamics and organization to promote epithelial differentiation. How KIF17 activity is regulated during this process remains unclear. Several kinesins, including KIF17, adopt compact and extended conformations that reflect autoinhibited and active states, respectively.

Atypical protein kinase Cλ is critical for growth factor receptor-induced dorsal ruffle turnover and cell migration.

Gα13, a member of the heterotrimeric G proteins, is critical for actin cytoskeletal reorganization and cell migration. Previously we have shown that Gα13 is essential for both G protein-coupled receptor and receptor tyrosine kinase-induced actin cytoskeletal reorganization such as dynamic dorsal ruffle turnover and cell migration. Ric-8A, a non-receptor guanine nucleotide exchange factor for some heterotrimeric G proteins, is critical for coupling receptor tyrosine kinases to Gα13.

Direct regulation of microtubule dynamics by KIF17 motor and tail domains.

KIF17 is a kinesin-2 family motor that interacts with EB1 at microtubule (MT) plus-ends and contributes to MT stabilization in epithelial cells. The mechanism by which KIF17 affects MTs and how its activity is regulated are not yet known. Here, we show that EB1 and the KIF17 autoinhibitory tail domain (KIF17-Tail) interacted competitively with the KIF17 catalytic motor domain (K370).

PH-domain-dependent selective transport of p75 by kinesin-3 family motors in non-polarized MDCK cells.

A key process during epithelial polarization involves establishment of polarized transport routes from the Golgi to distinct apical and basolateral membrane domains. To do this, the machinery involved in selective trafficking must be regulated during differentiation. Our previous studies showed that KIF5B selectively transports vesicles containing p75-neurotrophin receptors to the apical membrane of polarized, but not non-polarized MDCK cells.

Single-molecule analysis of CD9 dynamics and partitioning reveals multiple modes of interaction in the tetraspanin web.

Tetraspanins regulate cell migration, sperm-egg fusion, and viral infection. Through interactions with one another and other cell surface proteins, tetraspanins form a network of molecular interactions called the tetraspanin web. In this study, we use single-molecule fluorescence microscopy to dissect dynamics and partitioning of the tetraspanin CD9.

Temperature-dependent imaging of living cells by AFM.

Characterization of lateral organization of plasma membranes is a prerequisite to the understanding of membrane structure-function relationships in living cells. Lipid-lipid and lipid-protein interactions are responsible for the existence of various membrane microdomains involved in cell signalization and in numerous pathologies. Developing approaches for characterizing microdomains associate identification tools like recognition imaging with high-resolution topographical imaging.

Continuous planar phospholipid bilayer supported on porous silicon thin film reflector.

Reconstituting artificial membranes for in vitro studies of cell barrier mechanisms and properties is of major interest in biology. Here, artificial membranes supported on porous silicon photonic crystal reflectors are prepared and investigated. The materials are of interest for label-free probing of supported membrane events such as protein binding, molecular recognition, and transport.