Biology subjects

Pham, A. T.

Publications and source records attributed to Pham, A. T..

3 recordsLinked to original sources

bioRxiv2022

Cell dichotomous role of STING in pulmonary hypertension

RationalePatients with constitutive activation of DNA sensing pathway through stimulator of interferon genes (STING), such as those with STING-Associated Vasculopathy with onset in Infancy (SAVI), frequently have complications related to pulmonary hypertension (PH). However, the role of STING-signaling in adult PH patients is heretofore undescribed. ObjectiveTo investigate the role of STING in PH development. Methods and ResultsPH was induced in global STING deficient or cell-specific STING deficient mice using either bleomycin or chronic hypoxia exposure. PH development was evaluated with right ventricular systolic pressure, Fulton index, histological and flow cytometric measurements. STING expression in patient lungs were examined using both immunohistochemistry and flow cytometry. Herein, we describe how STING overactivation in a SAVI mouse model results in a baseline elevation in pulmonary pressures, while global STING deficiency protects mice from PH development. Furthermore, STING-associated PH appears to be independent of type I Interferon (IFN) signaling. We further demonstrate a cellular dichotomous role of STING in PH development with STING expression by smooth muscle cells contributing to PH, and its activation on myeloid cells being pivotal in severe disease prevention. Finally, we demonstrate a STING-PD-L1 axis as necessary for disease progression, suggesting future potential therapeutic applications. ConclusionsOverall, these data provide concrete evidence of STING involvement in PH, establishing biologic plausibility for STING-related therapies in PH treatment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=198 HEIGHT=200 SRC="FIGDIR/small/518422v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@7f5b50org.highwire.dtl.DTLVardef@143e485org.highwire.dtl.DTLVardef@4fe1a4org.highwire.dtl.DTLVardef@66fe26_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

Expanded ACE2 dependencies of diverse SARS-like coronavirus receptor binding domains

Viral spillover from animal reservoirs can trigger public health crises and cripple the world economy. Knowing which viruses are primed for zoonotic transmission can focus surveillance efforts and mitigation strategies for future pandemics. Successful engagement of receptor protein orthologs is necessary during cross-species transmission. The clade 1 sarbecoviruses including SARS-CoV and SARS-CoV-2 enter cells via engagement of ACE2, while the receptor for clade 2 and clade 3 remains largely uncharacterized. We developed a mixed cell pseudotyped virus infection assay to determine whether various clade 2 and 3 sarbecovirus spike proteins can enter HEK 293T cells expressing human or Rhinolophus horseshoe bat ACE2 proteins. The receptor binding domains from BtKY72 and Khosta-2 used human ACE2 for entry, while BtKY72 and Khosta-1 exhibited widespread use of diverse rhinolophid ACE2s. A lysine at ACE2 position 31 appeared to be a major determinant of the inability of these RBDs to use a certain ACE2 sequence. The ACE2 protein from R. alcyone engaged all known clade 3 and clade 1 receptor binding domains. We observed little use of Rhinolophus ACE2 orthologs by the clade 2 viruses, supporting the likely use of a separate, unknown receptor. Our results suggest that clade 3 sarbecoviruses from Africa and Europe use Rhinolophus ACE2 for entry, and their spike proteins appear primed to contribute to zoonosis under the right conditions.

microbiology↗

bioRxiv2019

Interneuron dysfunction in a new knock-in mouse model of SCN1A GEFS+

Advances in genome sequencing have identified over 1300 mutations in the SCN1A sodium channel gene that result in genetic epilepsies. However, how individual mutations within SCN1A produce seizures remains elusive for most mutations. Previous work from our lab has shown that the K1270T (KT) mutation, which is linked to GEFS+ (Genetic Epilepsy with Febrile Seizure plus) in humans, causes reduced firing of GABAergic neurons in a Drosophila knock-in model. To examine the effect of this mutation in mammals, we introduced the equivalent KT mutation into the mouse Scn1a (Scn1aKT) gene using CRISPR/Cas9. Mouse lines carrying this mutation were examined in two widely used genetic backgrounds, C57BL/6NJ and 129x1/SvJ. In both backgrounds, homozygous mutants had spontaneous seizures and died by postnatal day 23. There was no difference in the lifespan of mice heterozygous for the mutation in either background when compared to wild-type littermates up to 6 months. Heterozygous mutants had heat-induced seizures at ~42 deg. Celsius, a temperature that did not induce seizures in wild-type littermates. In acute hippocampal slices, current-clamp recordings revealed a significant depolarized shift in action potential threshold and reduced action potential amplitude in parvalbumin-expressing inhibitory interneurons in Scn1aKT/+ mice. There was no change in the firing properties of excitatory CA1 pyramidal neurons. Our results indicate that Scn1aKT/+ mice develop seizures, and impaired action potential firing of inhibitory interneurons in Scn1aKT/+ mice may produce hyperexcitability in the hippocampus.

neuroscience↗