CCTα

In the cell, the correct folding of many proteins depends on the function of preexisting ones known as Molecular Chaperones (for a review see Hartl and Hayer-Hartl 2009). These, were defined as proteins that bind to and stabilize an otherwise unstable conformation of another protein, and by controlling binding and release, facilitate its correct fate in vivo, be it folding, oligomeric assembly, transport to a particular subcellular compartment, or disposal by degradation. Molecular chaperones do not convey steric information specifying correct folding: instead, they prevent incorrect interactions within and between nonnative peptides, thus typically increasing the yield but not the rate of folding reactions. Molecular chaperones are ubiquitous and comprise several protein families that are structurally unrelated (Hartl and Hayer-Hartl 2009). The Hsp70s and the Chaperonin families have been extensively studied

From cilia to cancer: the two splicing variants of the human TBCCD1 gene

Funds are from Instituto Politécnico de Lisboa, IPL/2017/CILIOPAT/ESTeSL.Almost all human genes that contain multiple exons undergo alternative splicing. Therefore, a single gene can originate multiple mRNA isoforms which causes a dramatic increase in the variability of the expected proteome. Noteworthy, phenotypic variability and disease susceptibility in human populations are related to alternative splicing. Published work from our group identified a new human centrosomal protein, TBCC domain-containing 1 (TBCCD1). Our studies revealed that this gene undergoes alternative splicing producing at least two transcripts encoding proteins. Here we analyze the differential functions of the two splicing variants (TBCCD1v1 and TBCCD1v2). Both variants present distinct cellular localization being TBCCD1v1 essentially centrosomal, whereas TBCCD1v2 is cytoplasmatic. The screening for TBCCD1v2 proximity interactome using BioID identified 19 proteins that functionally group in kinetochore, MT/cilia, and DNA-binding proteins. Striking, the overexpression of TBCCD1v2 decreases the levels of the kinetochore protein CENP-M, a protein upregulated in tumors. On the other hand, the TBCCD1v1 is involved in MT organization and is required to maintain the distal structure of the mother centriole. Our BioID screening for TBCCD1v1 interactors revealed 82 distinct proteins including several well-known proteins encoded by ciliopathy genes. A wider analysis of how TBCCD1v1 levels impact cellular physiological proteome showed that the group of proteins presenting fold changes in their levels vs control cells is enriched in proteins involved in focal adhesions, namely HSPA5/GRP-78/BiP, PDIA3, RPS10, MSN, TGM2, and PPP1R12A. Together our results show that we are still far from having a complete picture of the functional importance of TBCCD1 and how its deregulation may be associated not only with the development of ciliopathies but also with more common diseases like cancer.info:eu-repo/semantics/publishedVersio

The apicomplexan parasite Toxoplasma gondii

PTDC/CVT-CVT/31840/2017EXPL/CVT-EPI/1945/2013Toxoplasma gondii is a ubiquitous zoonotic parasite with an obligatory intracellular lifestyle. It relies on a specialized set of cytoskeletal and secretory organelles for host cell invasion. When infecting its felid definitive host, T. gondii undergoes sexual reproduction in the intestinal epithelium, producing oocysts that are excreted with the feces and sporulate in the environment. In other hosts and/or tissues, T. gondii multiplies by asexual reproduction. Rapidly dividing tachyzoites expand through multiple tissues, particularly nervous and muscular tissues, and eventually convert to slowly dividing bradyzoites which produce tissue cysts, structures that evade the immune system and remain infective within the host. Infection normally occurs through ingestion of sporulated oocysts or tissue cysts. While T. gondii is able to infect virtually all warm-blooded animals, most infections in humans are asymptomatic, with clinical disease occurring most often in immunocompromised hosts or fetuses carried by seronegative mothers that are infected during pregnancy.info:eu-repo/semantics/publishedVersio

The expression of tubulin cofactor A (TBCA) is regulated by a noncoding antisense Tbca RNA during testis maturation

BACKGROUND: Recently, long noncoding RNAs have emerged as pivotal molecules for the regulation of coding genes' expression. These molecules might result from antisense transcription of functional genes originating natural antisense transcripts (NATs) or from transcriptional active pseudogenes. TBCA interacts with β-tubulin and is involved in the folding and dimerization of new tubulin heterodimers, the building blocks of microtubules. METHODOLOGY/PRINCIPAL FINDINGS: We found that the mouse genome contains two structurally distinct Tbca genes located in chromosomes 13 (Tbca13) and 16 (Tbca16). Interestingly, the two Tbca genes albeit ubiquitously expressed, present differential expression during mouse testis maturation. In fact, as testis maturation progresses Tbca13 mRNA levels increase progressively, while Tbca16 mRNA levels decrease. This suggests a regulatory mechanism between the two genes and prompted us to investigate the presence of the two proteins. However, using tandem mass spectrometry we were unable to identify the TBCA16 protein in testis extracts even in those corresponding to the maturation step with the highest levels of Tbca16 transcripts. These puzzling results led us to re-analyze the expression of Tbca16. We then detected that Tbca16 transcription produces sense and natural antisense transcripts. Strikingly, the specific depletion by RNAi of these transcripts leads to an increase of Tbca13 transcript levels in a mouse spermatocyte cell line. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that Tbca13 mRNA levels are post-transcriptionally regulated by the sense and natural antisense Tbca16 mRNA levels. We propose that this regulatory mechanism operates during spermatogenesis, a process that involves microtubule rearrangements, the assembly of specific microtubule structures and requires critical TBCA levels

Balancing act: tubulin glutamylation and microtubule dynamics in Toxoplasma gondii

This research was funded by FCT-Fundação para a Ciência e Tecnologia, I.P. (Portugal) through CIISA - Centro de Investigação Interdisciplinar em Sanidade Animal, project UIDB/00276/2020 and Laboratório Associado para Ciência Animal e Veterinária (AL4AnimalS) project LA/P/0059/2020.The success of the intracellular parasite Toxoplasma gondii in invading host cells relies on the apical complex, a specialized microtubule cytoskeleton structure associated with secretory organelles. The T. gondii genome encodes three isoforms of both α- and β-tubulin, which undergo specific post-translational modifications (PTMs), altering the biochemical and biophysical proprieties of microtubules and modulating their interaction with associated proteins. Tubulin PTMs represent a powerful and evolutionarily conserved mechanism for generating tubulin diversity, forming a biochemical 'tubulin code' interpretable by microtubule-interacting factors. T. gondii exhibits various tubulin PTMs, including α-tubulin acetylation, α-tubulin detyrosination, Δ5α-tubulin, Δ2α-tubulin, α- and β-tubulin polyglutamylation, and α- and β-tubulin methylation. Tubulin glutamylation emerges as a key player in microtubule remodeling in Toxoplasma, regulating stability, dynamics, interaction with motor proteins, and severing enzymes. The balance of tubulin glutamylation is maintained through the coordinated action of polyglutamylases and deglutamylating enzymes. This work reviews and discusses current knowledge on T. gondii tubulin glutamylation. Through in silico identification of protein orthologs, we update the recognition of putative proteins related to glutamylation, contributing to a deeper understanding of its role in T. gondii biology.info:eu-repo/semantics/publishedVersio

Balancing act: tubulin glutamylation and microtubule dynamics in Toxoplasma gondii

The success of Toxoplasma gondii (intracellular parasite) host cell invasion relies on the apical complex, a specialized microtubule cytoskeleton structure associated with secretory organelles. The genome encodes three isoforms of both α- and β-tubulin which are altered by specific post-translational modifications (PTMs), changing the biochemical/biophysical proprieties of microtubules, and modulating their interaction with associated proteins. Tubulin PTMs are a powerful and evolutionarily conserved mechanism to generate tubulin diversity, forming a biochemical ‘tubulin code’ that can be ‘read’ by microtubule-interacting factors. The T. gondii tubulin PTMs are: α-tubulin acetylation, α-tubulin detyrosination, Δ5α-tubulin, Δ2α-tubulin, α- and β-tubulin polyglutamylation, and α- and α-tubulin methylation. Tubulin glutamylation is a key candidate to assist microtubule remodeling in Toxoplasma, being involved in the regulation of microtubule stability, dynamics, interaction with motor proteins, and severing enzymes. The correct balance of tubulin glutamylation is achieved by the coordinated action of polyglutamylases and deglutamylating enzymes. In this work, we will review and discuss the current knowledge on T. gondii tubulin glutamylation. By in silico identification of mammalian protein orthologs, we explored and updated the identification of putative proteins related to glutamylation, contributing to a better understanding of the role of tubulin glutamylation in T. gondii.info:eu-repo/semantics/publishedVersio

TBCCD1, a new centrosomal protein, is required for centrosome and Golgi apparatus positioning

In animal cells the centrosome is actively positioned at the cell center in close association with the nucleus. The mechanisms responsible for this are not completely understood. Here we report the first characterization of human TBCCD1, a protein related to tubulin cofactor C. TBCCD1 localizes at the centrosome and at the spindle midzone, midbody and basal bodies of primary and motile cilia. Knockdown of TBCCD1 in RPE-1 cells caused the dissociation of the centrosome from the nucleus and disorganization of the Golgi apparatus. TBCCD1 depleted cells are larger, less efficient in primary cilia assembly and their migration is slower in wound-healing assays. However, the microtubule nucleating activity of the centrosome is not affected by TBCCD1 silencing. We propose that TBCCD1 is a key regulator of centrosome positioning and consequently of internal cell organization

The nuclear levels of thioredoxin reductase 1, gamma-H2AX, and yap are modulated by primary cilia in response to high glucose levels

This work was funded by Instituto Politécnico de Lisboa IPL/2021/ ObeCil_ESTeSL & IPL/ WintCilGlu_ESTeSL. H&TRC authors gratefully acknowledge the FCT/MCTES national support through the UIDB/05608/2020 and UIDP/05608/2020.Diabetes is a condition characterized by impaired regulation of blood glucose levels, leading to various complications such as hypertension, cardiovascular disease, and retinopathy. Diabetic retinopathy (DR), caused by a disrupted retinal blood barrier, is associated with oxidative stress resulting from dysregulated glucose levels in the retina. The primary cilium, an organelle involved in energy balance and glucose homeostasis, has been implicated in the development of various diseases known as ciliopathies, which include overlapping phenotypes such as obesity, diabetes, and retinopathy. This study aims to investigate the impact of high glucose levels on primary cilia assembly in retinal pigment epithelium (RPE-1) cell cultures and explore the role of cilia in the cellular response to high glucose levels. RPE-1 cells were grown in media supplemented with different glucose concentrations (5 mM, 25 mM, and 5 mM glucose + 20 mM mannitol), and cilia assembly was induced before or after glucose supplementation. The results revealed that glucose supplementation did not affect the number of ciliated cells, but cells supplemented with 25 mM glucose exhibited shorter cilia. To understand the role of cilia in response to high glucose levels, the nuclear levels of thioredoxin reductase 1 (TRXR1), a key enzyme involved in combating oxidative stress triggered by hyperglycemia, were evaluated. Additionally, γH2AX, a marker of DNA breaks and cellular senescence, and YAP, a Hippo pathway effector, were examined. It was observed that glucose supplementation, particularly at high levels (25 mM), influenced the nuclear levels of TRXR1, γH2AX, and YAP. Notably, the presence of cilia modulated the cellular response to high glucose levels, modulating the levels of these proteins. These preliminary findings indicate that primary cilia significantly influence the cellular response to high glucose concentrations, which are known to induce oxidative stress and potentially contribute to the development of DR.info:eu-repo/semantics/publishedVersio

First case in Portugal

A significant dysfunction of another organ is usually considered an absolute contraindication for lung transplantation, unless multiorgan transplantation is indicated and practical, as is the case of combined lung-kidney transplantation. Few cases of combined lung-kidney transplantation have been described in the literature; however, it is known that, in certain cases, it is the only way to offer an opportunity to selected patients with renal and lung dysfunction. The authors are not aware of any previously published case of a patient receiving both extracorporeal membrane oxygenation and continuous venovenous hemodiafiltration as a bridge for combined kidney-lung transplantation. The authors present the first case of combined lung-kidney transplantation performed in Portugal.publishersversionpublishe

Tick-borne diseases in asymptomatic cattle from São Miguel Island, Azores – A clinical perspective

Tick-borne diseases in asymptomatic cattle from São Miguel Island, Azores – A clinical perspective Introduction/Background: The Azores archipelago is one of the regions with the highest cattle production, in Portugal. Outbreaks of tick-borne (TB) diseases have been reported by local field veterinarians and different tick species are described in São Miguel. At this study, we decided to investigate the presence of some of these agents in asymptomatic cattle, in S. Miguel. Materials & methods: In October 2019, 10 blood samples from each of 10 farms were randomly selected. Species belonging to the Babesia/Theileria and Anaplasma/ Ehrlichia genus were tested by PCR screening. Results: There were 45 positive samples later confirmed as species belonging to the Theileria orientalis group (45/100, 45%), in 9 farms (9/10, 90%) and it was also possible to identify Anaplasma bovis, in 2 animals, at two farms (2/10, 20%). Discussion: As far as we were able to verify, this is the first reference to the presence of these agents in S. Miguel. However, although asymptomatic, the repercussions associated with these infections are probably being underestimated or confused with other health problems. Since ixodids were not found in cows, other factors may be contributing to the high percentage of positive samples found, such as poor management practices. This is clearly an interesting subject for further investigation, as a better understanding of the life cycle of these parasites will contribute to their control