The E3 ubiquitin ligase COP1 regulates salt tolerance via GIGANTEA degradation in roots.

Excess soil salinity significantly impairs plant growth and development. Our previous reports demonstrated that the core circadian clock oscillator GIGANTEA (GI) negatively regulates salt stress tolerance by sequestering the SALT OVERLY SENSITIVE (SOS) 2 kinase, an essential component of the SOS pathway. Salt stress induces calcium-dependent cytoplasmic GI degradation, resulting in activation of the SOS pathway; however, the precise molecular mechanism governing GI degradation during salt stress remains enigmatic. Here, we demonstrate that salt-induced calcium signals promote the cytoplasmic partitioning of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), leading to the 26S proteasome-dependent degradation of GI exclusively in the roots. Salt stress-induced calcium signals accelerate the cytoplasmic localization of COP1 in the root cells, which targets GI for 26S proteasomal degradation. Align with this, the interaction between COP1 and GI is only observed in the roots, not the shoots, under salt-stress conditions. Notably, the gi-201 cop1-4 double mutant shows an enhanced tolerance to salt stress similar to gi-201, indicating that GI is epistatic to COP1 under salt-stress conditions. Taken together, our study provides critical insights into the molecular mechanisms governing the COP1-mediated proteasomal degradation of GI for salt stress tolerance, raising new possibilities for developing salt-tolerant crops.

Identification of ERAD-dependent degrons for the endoplasmic reticulum lumen.

Degrons are minimal protein features that are sufficient to target proteins for degradation. In most cases, degrons allow recognition by components of the cytosolic ubiquitin proteasome system. Currently, all of the identified degrons only function within the cytosol. Using Saccharomyces cerevisiae, we identified the first short linear sequences that function as degrons from the endoplasmic reticulum (ER) lumen. We show that when these degrons are transferred to proteins, they facilitate proteasomal degradation through the ERAD system. These degrons enable degradation of both luminal and integral membrane ER proteins, expanding the types of proteins that can be targeted for degradation in budding yeast and mammalian tissue culture. This discovery provides a framework to target proteins for degradation from the previously unreachable ER lumen and builds toward therapeutic approaches that exploit the highly-conserved ERAD system.

Astrocytes are involved in the formation of corpora amylacea-like structures from neuronal debris in the CA1 region of the rat hippocampus after ischemia.

Recently, we demonstrated that the corpora amylacea (CA), a glycoprotein-rich aggregate frequently found in aged brains, accumulates in the ischemic hippocampus and that osteopontin (OPN) mediates the entire process of CA formation. Therefore, this study aimed to elucidate the mechanisms by which astrocytes and microglia participate in CA formation during the late phase (4-12 weeks) of brain ischemia. Based on various morphological analyses, including immunohistochemistry, in situ hybridization, immunoelectron microscopy, and correlative light and electron microscopy, we propose that astrocytes are the primary cells responsible for CA formation after ischemia. During the subacute phase after ischemia, astrocytes, rather than microglia, express Opn messenger ribonucleic acid and OPN protein, a surrogate marker and key component of CA. Furthermore, the specific localization of OPN in the Golgi complex suggests that it is synthesized and secreted by astrocytes. Astrocytes were in close proximity to type I OPN deposits, which accumulated in the mitochondria of degenerating neurons before fully forming the CA (type III OPN deposits). Throughout CA formation, astrocytes remained closely attached to OPN deposits, with their processes exhibiting well-developed gap junctions. Astrocytic cytoplasmic protein S100ß, a calcium-binding protein, was detected within the fully formed CA. Additionally, ultrastructural analysis revealed direct contact between astroglial fibrils and the forming facets of the CA. Overall, we demonstrated that astrocytes play a central role in mediating CA formation from the initial stages of OPN deposit accumulation to the evolution of fully formed CA following transient ischemia in the hippocampus.

Higher body mass index and anti-drug antibodies predict the discontinuation of anti-TNF agents in Korean patients with axial spondyloarthritis / O maior índice de massa corporal e a presença de anticorpos antifármacos predizem a interrupção no uso de agentes anti-TNF em pacientes sul-coreanos com espondiloartrite axial

ABSTRACT Objective: The development of anti-drug antibodies against tumor necrosis factor inhibitors is a likely explanation for the failure of TNF-inhibitors in patients with spondyloarthritis. Our study determined the existence and clinical implications of ADAbs in axial spondyloarthritis patients. Methods: According to the Assessment of SpondyloArthritis International Society classification criteria for axial spondyloarthritis, patients treated with adalimumab or infliximab were recruited consecutively. Serum samples were collected at enrollment to measure anti-drug antibodies and drug levels. Results: Of 100 patients, the mean duration of current TNF inhibitor use was 22.3 ± 17.9 months. Anti-drug antibodies were detected in 5 of 72 adalimumab users compared to 5 of 28 infliximab users (6.9% vs. 17.9%). Anti-drug antibodies-positive patients had a significantly higher body mass index than anti-drug antibodies-negative patients among both adalimumab (28.4 ± 5.9 kg/m2 vs. 24.3 ± 2.9 kg/m2, respectively, p = 0.01) and infliximab users (25.9 ± 2.8 kg/m2 vs. 22.6 ± 2.8 kg/m2, respectively, p = 0.02). During the median 15-month follow-up period, drug discontinuation occurred more frequently in the anti-drug antibodies-positive group than the anti-drug antibodies-negative group (30.0% vs. 6.5%, respectively, p = 0.04). In logistic regression, anti-drug antibodies positivity (OR = 5.85, 95% CI 1.19-28.61, p = 0.029) and body mass index (OR = 4.35, 95% CI 1.01-18.69, p = 0.048) were associated with a greater risk of stopping TNF inhibitor treatment. Conclusions: Our result suggests that the presence of anti-drug antibodies against adalimumab and infliximab as well as a higher body mass index can predict subsequent drug discontinuation in axial spondyloarthritis patients.

RESUMO Objetivo: O desenvolvimento de anticorpos antifármacos (ADAb) contra o fator de necrose tumoral (TNF) é uma explicação provável para a falha dos anti-TNF em pacientes com espondiloartrites (EspA). O presente estudo determinou a presença e as implicações clínicas dos ADAb em pacientes com EspA axiais. Métodos: De acordo com os critérios de classificação para EspA axial da Assessment of SpondyloArthritis International Society, recrutaram-se consecutivamente pacientes tratados com adalimumabe ou infliximabe. Coletaram-se amostras de soro no momento da entrada no estudo para medir os níveis de ADAb e de fármaco. Resultados: Dos 100 pacientes, a duração média de uso dos anti-TNF atuais foi de 22,3 ± 17,9 meses. Os ADAb foram detectados em cinco de 72 pacientes em uso de adalimumabe, em comparação com cinco de 28 usuários de infliximabe (6,9% vs. 17,9%). Os pacientes ADAb-positivos tinham um índice de massa corporal maior do que aqueles ADAb-negativos, tanto entre indivíduos em uso de adalimumabe (28,4 ± 5,9 kg/m2 vs. 24,3 ± 2,9 kg/m2, respectivamente, p = 0,01) quanto de infliximabe (25,9 ± 2,8 kg/m2 vs. 22,6 ± 2,8 kg/m2 respectivamente, p = 0,02). Durante o período médio de seguimento de 15 meses, a suspensão do fármaco ocorreu com maior frequência no grupo ADAb-positivo do que no grupo ADAb-negativo (30,0% vs. 6,5%, respectivamente, p = 0,04). Na regressão logística, a positividade no ADAb (OR = 5,85, IC 95% 1,19 a 28,61, p = 0,029) e o IMC (OR = 4,35, IC 95% 1,01 a 18,69, p = 0,048) esteve associada a um maior risco de interromper o tratamento com anti-TNF. Conclusões: Os resultados do presente estudo sugerem que a presença de ADAb contra o adalimumabe e o infliximabe, bem como um IMC mais alto, pode predizer a subsequente interrupção do fármaco em pacientes com EspA axial.