Biology subjects

Gonzalez, A. J.

Publications and source records attributed to Gonzalez, A. J..

4 recordsLinked to original sources

bioRxiv2023

A new Karyopherin-β2 binding PY-NLS epitope of HNRNPH2 is linked to neurodevelopmental disorders

The normally nuclear HNRNPH2 is mutated in HNRNPH2-related X-linked neurodevelopmental disorder causing the protein to accumulate in the cytoplasm. Interactions of HNRNPH2 with its importin Karyopherin-{beta}2 (Transportin-1) had not been studied. We present a structure that shows Karyopherin-{beta}2 binding HNRNPH2 residues 204-215, a proline-tyrosine nuclear localization signal or PY-NLS that contains a typical R-X2-4-P-Y motif, 206RPGPY210, followed a new Karyopherin-{beta}2 binding epitope at 211DRP213 that make many interactions with Karyopherin-{beta}2 W373. Mutations at each of these sites decrease Karyopherin-{beta}2 binding affinities by 70-100 fold, explaining aberrant accumulation in cells and emphasizing the role of nuclear import defects in the disease. Sequence/structure analysis suggests that the new epitope C-terminal of the PY-motif, which binds Karyopherin-{beta}2 W373, is rare and thus far limited to close paralogs HNRNPH2, HNRNPH1 and HNRNPF. Karyopherin-{beta}2 W373, a HNRNPH2-binding hotspot, corresponds to W370 of close paralog Transportin-2, a site of pathological variants in patients with neurodevelopmental abnormalities, suggesting that Transportin-2-HNRNPH2/H1/F interactions may be compromised in the abnormalities. SummaryHNRNPH2 variants in HNRNPH2-related X-linked neurodevelopmental disorder aberrantly accumulate in the cytoplasm. A structure of Karyopherin-{beta}2*HNRNPH2 explains nuclear import defects of the variants, reveals a new NLS epitope that suggests mechanistic changes in pathological variants of Karyopherin-{beta}2 paralog Transportin-2.

biophysics↗

bioRxiv2020

Rhinovirus reduces the severity of subsequent respiratory viral infections, which is associated with dampened inflammatory responses

Coinfection by unrelated viruses in the respiratory tract is common and can result in changes in disease severity compared to infection by individual virus strains. We have previously shown that inoculation of mice with rhinovirus (RV) two days prior to inoculation with a lethal dose of influenza A virus (PR8), provides complete protection against mortality and reduces morbidity. In this study, we extended that finding to a second lethal respiratory virus, pneumonia virus of mice (PVM) and analyzed potential mechanisms whereby RV reduces lethal viral pneumonia caused by PR8 and PVM. RV prevented mortality and weight loss associated with PVM infection, suggesting that RV-mediated protection is more effective against PVM than PR8. Major changes in host gene expression upon PVM infection were delayed compared to PR8, which likely provides a larger time frame for RV-induced gene expression to alter the course of disease. Overall, RV induced earlier recruitment of inflammatory cells, while these populations were reduced at later times in RV-inoculated mice. Findings common to both virus pairs included upregulated expression of mucin-associated genes and dampening of inflammation-related genes in mice that were inoculated with RV prior to lethal virus infection. However, type I IFN signaling was required for RV-mediated protection against PR8, but not PVM. IFN signaling had minor effects on PR8 replication and contributed to controlling neutrophilic inflammation and subsequent hemorrhagic lung pathology in RV/PR8 infected mice. These findings, combined with differences in virus replication levels and disease severity, suggest that the suppression of inflammation in RV/PVM infected mice may be due to early, IFN-independent suppression of viral replication, while in RV/PR8 infected mice may be due to IFN-dependent modulation of immune responses. Thus, a mild upper respiratory viral infection can reduce the severity of a subsequent severe viral infection in the lungs through virus-dependent mechanisms. Author SummaryRespiratory viruses from diverse families co-circulate in human populations and are frequently detected within the same host. Though clinical studies suggest that infection by more than one unrelated respiratory virus may alter disease severity, animal models in which we can control the doses, timing, and strains of coinfecting viruses are critical to understand how coinfection affects disease severity. In this study, we compared gene expression and immune cell recruitment between two pairs of viruses (RV/PR8 and RV/PVM) inoculated sequentially in mice that both result in reduced severity compared to lethal infection by PR8 or PVM alone. Reduced disease severity was associated with suppression of inflammatory responses in the lungs. However, differences in disease kinetics and host and viral gene expression suggest that protection by coinfection with RV may be due to distinct molecular mechanisms. Indeed, we found that antiviral cytokine signaling was required for RV-mediated protection against lethal infection by PR8, but not PVM.

microbiology↗

bioRxiv2018

Attenuation of influenza A virus disease severity by viral co-infection in a mouse model

Influenza viruses and rhinoviruses are responsible for a large number of acute respiratory viral infections in human populations and are detected as co-pathogens within hosts. Clinical and epidemiological studies suggest that co-infection by rhinovirus and influenza virus may reduce disease severity and that they may also interfere with each others spread within a host population. To determine how co-infection by these two unrelated respiratory viruses affects pathogenesis, we established a mouse model using a minor serogroup rhinovirus (RV1B) and mouse-adapted influenza A virus (PR8). Infection of mice with RV1B two days before PR8 reduced pathogenesis of mild to moderate, but not severe PR8 infections. Disease attenuation was associated with an early inflammatory response in the lungs and enhanced clearance of PR8. However, co-infection by RV1B did not reduce PR8 viral loads early in infection or inhibit replication of PR8 within respiratory epithelia or in vitro. Inflammation in co-infected mice remained focal, in comparison to diffuse inflammation and damage in the lungs of mice infected by PR8. These findings suggest that RV1B stimulates an early immune response that clears PR8 while limiting excessive pulmonary inflammation. The timing of RV1B co-infection was a critical determinant of protection, suggesting that sufficient time is needed to induce this response. Finally, disease attenuation was not unique to RV1B: co-infection by a murine coronavirus two days before PR8 also reduced disease severity. This model will be critical for understanding the mechanisms responsible for attenuation of influenza disease during co-infection by unrelated respiratory viruses.

microbiology↗

bioRxiv2018

Novel antimicrobial peptide discovery using machine learning and biophysical selection of minimal bacteriocin domains

Bacteriocins are ribosomally produced antimicrobial peptides that represent an untapped source of promising antibiotic alternatives. However, inherent challenges in isolation and identification of natural bacteriocins in substantial yield have limited their potential use as viable antimicrobial compounds. In this study, we have developed an overall pipeline for bacteriocin-derived compound design and testing that combines sequence-free prediction of bacteriocins using a machine-learning algorithm and a simple biophysical trait filter to generate minimal 20 amino acid peptide candidates that can be readily synthesized and evaluated for activity. We generated 28,895 total 20-mer peptides and scored them for charge, -helicity, and hydrophobic moment, allowing us to identify putative peptide sequences with the highest potential for interaction and activity against bacterial membranes. Of those, we selected sixteen sequences for synthesis and further study, and evaluated their antimicrobial, cytotoxicity, and hemolytic activities. We show that bacteriocin-based peptides with the overall highest scores for our biophysical parameters exhibited significant antimicrobial activity against E. coli and P. aeruginosa. Our combined method incorporates machine learning and biophysical-based minimal region determination, to create an original approach to rapidly discover novel bacteriocin candidates amenable to rapid synthesis and evaluation for therapeutic use.

microbiology↗