Neurogranin (Ng) is a 78-amino-acid-long protein concentrated at dendritic spines of forebrain neurons that is involved in synaptic plasticity through the regulation of CaM (calmodulin)-mediated signalling. Ng features a central IQ motif that mediates binding to CaM and is phosphorylated by PKC (protein kinase C). We have analysed the subcellular distribution of Ng and found that it associates to cellular membranes in rat brain. In vitro binding assays revealed that Ng selectively binds to PA (phosphatidic acid) and that this interaction is prevented by CaM and PKC phosphorylation. Using the peptide Ng-(29-47) and a mutant with an internal deletion (Ng-IQless), we have shown that Ng binding to PA and to cellular membranes is mediated by its IQ motif. Ng expressed in NIH-3T3 cells accumulates at peripheral regions of the plasma membrane and localizes at intracellular vesicles that can be clearly visualized following saponin permeabilization. This distribution was affected by PLD (phospholipase D) and PIP5K (phosphatidylinositol 4-phosphate 5-kinase) overexpression. Based on these results, we propose that Ng binding to PA may be involved in Ng accumulation at dendritic spines and that Ng could modulate PA signalling in the postsynaptic environment.

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Information on Clostridioides difficile infection (CDI) in patients with COVID-19 is scarce and points to an overall decrease of episodes during the pandemic. This situation results paradoxical, as COVID-19 patients had long periods of hospital stay and high use of antibiotics. We conducted a retrospective study from January 1st 2019 to December 31st 2020 comparing the incidence of hospital-acquired episodes of CDI (HA-CDI) among patients with and without COVID-19 admitted to our institution. During the study period, there were 47,048 patient admissions in 2019, 35,662 admissions of patients without COVID-19 in 2020 and 6,763 of COVID-19 patients. There were 68 episodes of HA-CDI in COVID-19 patients (14.75/10,000 days), 159 in 2020-non-COVID-19 patients (5.54/10,000 days) and 238 in 2019 (6.80/10,000 days). Comparison of HA-CDI in COVID-19 and non-COVID-19 patients indicates it occurs more frequently, in terms of CDI disease severity, COVID-19 does not seem to have a negative impact.