Biology subjects

Cereceda, K.

Publications and source records attributed to Cereceda, K..

3 recordsLinked to original sources

bioRxiv2025

Proteasome Inhibition Reduces NBR1 Protein Levels in mATG8-Deficient Cells Independently of Lysosomal Degradation and RAB27A

Autophagy is a lysosome-dependent degradation process that involves autophagosome formation, typically mediated by mammalian ATG8 proteins (mATG8s). Autophagosomes can still form in their absence, suggesting alternative mechanisms. NBR1, a selective autophagy receptor, has been shown to compensate for autophagy defects. Here, we examined NBR1 regulation under proteotoxic stress in mATG8s-deficient HeLa cells. NBR1 levels were elevated in mATG8s knockout (KO) cells under basal conditions but decreased significantly after treatment with the proteasome inhibitor MG132. This reduction was not prevented by lysosomal inhibition with BafA1, indicating a non-lysosomal mechanism. Silencing of RAB27A reduced basal NBR1 levels, and the effects of MG132 were no longer observed, likely due to already diminished NBR1. Remaining NBR1 localized to puncta positive for ubiquitin and the ESCRT-0 component HRS, suggesting involvement of a ubiquitin-dependent endosomal pathway. Overall, our results suggest that under proteotoxic stress and impaired autophagy, cells activae alternative routes, potentially involving unconventional secretion, to regulate NBR1 levels. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/664987v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@10568bcorg.highwire.dtl.DTLVardef@1f3d53org.highwire.dtl.DTLVardef@f33508org.highwire.dtl.DTLVardef@11ec28e_HPS_FORMAT_FIGEXP M_FIG C_FIG Created with BioRender https://BioRender.com/geoh3sz In the absence of mATG8s, NBR1 may be recruited to multivesicular bodies (MVBs) via HRS, for later degradation in lysosomes (left panel). Under proteasomal inhibition (right panel), NBR1 associated with MVBs (with ubiquitinated cargos) is downregulated, independent of lysosomes. Possibly, this downregulation is due to a secretion process, through a RAB27A-independent mechanism.

cell biology↗

bioRxiv2021

Serological Profile Of Specific Antibodies Against Dominant Antigens Of SARS-CoV-2 In Chilean COVID-19 Patients.

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2 and has been a pandemic since March 2020. Currently, the virus has infected more than 50 million people worldwide and more than half a million in Chile. For many coronaviruses, Spike (S) and Nucleocapsid (N) proteins are described as major antigenic molecules, inducing seroconversion and production of neutralizing antibodies. In this work, we evaluated the presence in serum of IgM, IgA and IgG antibodies against N and S proteins of SARS-CoV-2 using western blot, and developed an ELISA test for the qualitative characterization of COVID-19 patients. Patients with an active infection or who have recovered from COVID-19 showed specific immunoblotting patterns for the recombinants S protein and its domains S1 and S2, as well as for the N protein of SARS-CoV-2. Anti-N antibodies were more frequently detected than anti-S or anti-S1-RBD antibodies. People who were never exposed to SARS-CoV-2 did not show reactivity. Finally, indirect ELISA assays using N and S1-RBD proteins, alone or in combination, were established with variable sensitivity and specificity depending on the antigen bound to the solid phase. Overall, Spike showed higher specificity than the nucleocapsid, and comparable sensitivity for both antigens. Both approaches confirmed the seroconversion after infection and allowed us to implement the analysis of antibodies in blood for research purposes in a local facility.

biochemistry↗

bioRxiv2020

The proteasomal deubiquitinating enzyme PSMD14 regulates macroautophagy by controlling Golgi-to-ER retrograde transport

Ubiquitination regulates several biological processes. Here, we search for ubiquitin-related genes implicated in protein membrane trafficking performing a High-Content siRNA Screening including 1,187 genes of the human "ubiquitinome" using Amyloid Precursor Protein (APP) as a reporter. We identified the deubiquitinating enzyme PSMD14, a subunit of the 19S regulatory particle of the proteasome, specific for K63-Ub chains in cells, as a novel key regulator of Golgi-to-endoplasmic reticulum (ER) retrograde transport. Silencing or pharmacological inhibition of PSMD14 caused a robust and rapid inhibition of Golgi-to-ER retrograde transport which leads to a potent blockage of macroautophagy by a mechanism associated with the retention of Atg9A and Rab1A at the Golgi apparatus. Because pharmacological inhibition of the proteolytic core of the 20S proteasome did not recapitulate these effects, we concluded that PSMD14, and their K-63-Ub chains, act as a crucial regulator factor for macroautophagy by controlling Golgi-to-ER retrograde transport.

cell biology↗