Biology subjects

Cid-Rosas, M.

Publications and source records attributed to Cid-Rosas, M..

3 recordsLinked to original sources

bioRxiv2026

A multimodal perturbation atlas defines the phenotypic resolution of cellular morphology.

Modeling cellular behavior requires measurements that capture how cells evolve across time, environments, and interventions. Microscopy is uniquely suited to this goal: it is non-destructive and can be applied to living cells in their native context. Yet its phenotypic resolving power remains incompletely characterized relative to molecular assays. Here, we present a multimodal perturbation atlas of 1,000 pooled CRISPR knockouts in A549 cells, profiled by fluorescence microscopy (42 live, 13 fixed markers), label-free quantitative phase imaging of the same live cells (at single timepoints), and single-cell RNA sequencing (scRNA-seq). We develop deep learning frameworks to interpret the rich cell-biological signatures in these ~65M single-cell profiles. At matched reagent cost, phase imaging exceeds the phenotypic resolution of both fluorescence imaging and scRNA-seq, and more reliably recovers higher-order pathway organization. These results establish intrinsic morphology as a high-precision readout of cellular state, and lay a foundation for live-cell profiling of phenotypic trajectories.

systems biology↗

bioRxiv2026

V-SWITCH: A single-vector OFF-to-ON fluorescent reporter of live RNA virus infections

Fluorescent reporters of viral infection are powerful tools for studying viral pathogenesis and host-pathogen interactions. Here, we present V-SWITCH, a highly modular, single-vector, cell-based OFF-to-ON fluorescent reporter that enables robust detection of viral infection in living cells. V-SWITCH is based on a split mNeonGreen (mNG) system employing a release-and-capture mechanism. In the "OFF" state, the mNG3A(1-10) fragment is anchored to the endoplasmic reticulum via a Sec61 transmembrane domain, while the mNG(11) fragment, fused to BFP, is constitutively expressed in the nucleus. Upon infection, the viral protease cleaves a protease cleavage site (PCS) adjacent to the mNG3A(1-10) fragment, liberating it for translocation into the nucleus. There, it complements mNG(11) to reconstitute fluorescence. The constitutive BFP serves as both an expression control and a nuclear segmentation marker for image analysis. Each module in this dual-cassette design is flanked by unique restriction sites allowing rapid swapping of virus-specific PCS, split fluorophores, membrane anchors, and promoters. We demonstrate the versatility of the V-SWITCH reporter for several viruses (Dengue virus, Zika virus, West Nile virus and Human Coronavirus OC43) in several cell lines (A549, BJ-5 fibroblasts, HEK293T and HeLa). Reporter activation enables clear discrimination of infected and uninfected cells by flow cytometry and reveals time-dependent and heterogeneous infection dynamics by live-cell imaging at single-cell resolution. Importantly, we demonstrate the potential of V-SWITCH to support both rapid functional screening for host factor dependencies, as well as high-throughput compound screening to enable antiviral discovery and comparative evaluation of therapeutic strategies across multiple viruses and cell types.

microbiology↗

bioRxiv2024

Conserved residues of the immunosuppressive domain of MLV are essential for regulating the fusion-critical SU-TM disulfide bond

The ENV protein of murine leukemia virus (MLV) is the prototype of a large clade of retroviral fusogens, collectively known as gamma-type Envs. Gamma-type ENVs are found in retroviruses and related endogenous retroviruses (ERV) representing a broad range of vertebrate hosts. All gamma-type Envs contain a highly conserved stretch of 26-residues in the transmembrane subunit (TM) comprising two motifs, a putative immunosuppressive domain (ISD) and a CX6CC motif. The extraordinary conservation of the ISD and its invariant association with the CX6CC suggests a fundamental contribution to Env function. To investigate function of the ISD, we characterized several mutants with single amino acid substitutions at conserved positions in the MLV ISD. A majority abolished infectivity, although we did not observe a corresponding loss in intrinsic ability to mediate membrane fusion. Ratios of the surface subunit (SU) to capsid protein (CA) in virions were diminished for a majority of the mutants, while TM/CA ratios were similar to wild type. Specific loss of SU reflected premature isomerization of the labile disulfide bond that links SU and TM prior to fusion and entry. Indeed, all non-infectious mutants displayed significantly lower disulfide stability than wild type MLV Env. These results reveal a role for residues at MLV ISD positions 2, 3, 4, 7, and 10 in regulating a late step in fusion, and suggest that the ISD is part of a larger domain, encompassing both the ISD and CX6CC motifs, that is critical for formation and regulation of the metastable, intersubunit disulfide bond. IMPORTANCEThe gamma-type Env is an extremely prevalent viral fusogen, extensively found within retroviruses and endogenous loci across vertebrate species and are further found in filoviruses such as Ebola virus. The fusion mechanism of gamma-type Envs is unique from other Class I fusogens such as those of IAV and HIV-1. Gamma-type Envs contain a hallmark feature known as the immunosuppressive domain (ISD) that has been the subject of some controversy in the literature surrounding its putative immunosuppressive effects. Despite the distinctive conservation of the ISD, little has been done to investigate the role of this region for the function of this widespread fusogen. Our work demonstrates the importance of the ISD for the function of gamma-type Envs in infection, particularly in regulating the intermediate steps of fusion with the host membrane. Understanding the fusion mechanism of gamma-type Envs has broad implications for understanding entry of extant viruses and aspects of host biology connected to co-opted endogenous gamma-type Envs.

microbiology↗