Biology subjects

Gad, H. H.

Publications and source records attributed to Gad, H. H..

3 recordsLinked to original sources

bioRxiv2021

Cryo-EM structure of the human NKCC1 transporter reveals mechanisms of ion coupling and specificity

The sodium-potassium-chloride transporter NKCC1 (SLC12A2) performs Na+-dependent Cl- and K+ ion uptake across plasma membranes. NKCC1 is important for regulating e.g. cell volume, hearing, blood pressure, and chloride gradients defining GABAergic and glycinergic signaling in brain. Here, we present a 2.6 [A] resolution cryo-electron microscopy (cryo-EM) structure of human NKCC1 in the substrate-loaded (Na+, K+, 2 Cl-) and inward-facing conformation adopting an occluded state that has also been observed for the SLC6 type transporters MhsT and LeuT. Cl- binding at the Cl1 site together with the nearby K+ ion provide a crucial bridge between the LeuT-fold scaffold and bundle domains. Cl- ion binding at the Cl2 site seems to undertake a structural role similar to a conserved glutamate of SLC6 transporters and may allow for chloride-sensitive regulation of transport. Supported by functional studies in mammalian cells and computational simulations we describe the Na+ binding site and a putative Na+ release pathway along transmembrane helix 5. The results provide insight into the structure-function relationship of NKCC1 with broader implications for other SLC12 family members.

biochemistry↗

bioRxiv2021

Effective interferon (IFN)-lambda treatment regimen to control lethal MERS-CoV infection in mice

Effective broad-spectrum antivirals are critical to prevent and control emerging human coronavirus (hCoV) infections. Despite considerable progress made towards identifying and evaluating several synthetic broad-spectrum antivirals against hCoV infections, a narrow therapeutic window has limited their success. Enhancing the endogenous interferon (IFN) and interferon-stimulated gene (ISG) response is another antiviral strategy known for decades. However, the side effects of pegylated type-I IFNs (IFN-Is) and the pro-inflammatory response detected after delayed IFN-I therapy have discouraged their clinical use. In contrast to IFN-Is, IFN-{lambda}, a dominant IFN at the epithelial surface, is shown to be less pro-inflammatory. Consequently, we evaluated the prophylactic and therapeutic efficacy of IFN-{lambda} in hCoV infected airway epithelial cells and mice. Human primary airway epithelial cells treated with a single dose of IFN-I (IFN-) and IFN-{lambda} showed similar ISG expression, whereas cells treated with two doses of IFN-{lambda} expressed elevated levels of ISG compared to IFN-a treated cells. Similarly, mice treated with two dose IFN-{lambda} were better protected compared to mice receiving a single dose, and a combination of prophylactic and delayed therapeutic regimens completely protected mice from lethal MERS-CoV-infection. A two dose IFN-{lambda} regimen significantly reduced lung viral RNA and inflammatory cytokine levels with marked improvement in lung inflammation. Collectively, we identify an ideal regimen for IFN-{lambda} use and demonstrate the protective efficacy of IFN-{lambda} in MERS-CoV infected mice.

immunology↗

bioRxiv2020

Type I and III interferons disrupt lung epithelial repair during recovery from viral infection

Excessive cytokine signalling frequently exacerbates lung tissue damage during respiratory viral infection. Type I and III interferons (IFN-/{beta} and IFN-{lambda}) are host-produced antiviral cytokines and currently considered as COVID-19 therapy. Prolonged IFN-/{beta} responses can lead to harmful proinflammatory effects, whereas IFN-{lambda} mainly signals in epithelia, inducing localised antiviral immunity. Here we show that IFN signalling interferes with lung repair during influenza recovery, with IFN-{lambda} driving these effects most potently. IFN-induced p53 directly reduces epithelial proliferation and differentiation, increasing disease severity and susceptibility to bacterial superinfections. Hence, excessive or prolonged IFN-production aggravates viral infection by impairing lung epithelial regeneration. Therefore, timing and duration are critical parameters of endogenous IFN action, and should be considered carefully for IFN therapeutic strategies against viral infections like influenza and COVID-19. One Sentence SummaryA novel IFN-mediated mechanism of immunopathology during respiratory virus infection by interference with lung tissue repair.

immunology↗