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Recent events

Seminars

Type of Event: Evaluation Examination
Speaker: M.Sc. Montserrat Ávila Zozaya
Day: 2022-05-12, at 14:00:00 hrs.
Place: Door closed with the committee
Title: Study of the cancer-associated pathophysiological function of the GAIN domain of Lphn3 in HEK293 cells
Abstract:

Latrophilin 3 (Lphn3 or ADGRL3) is a bipartite molecule that is a member of the adhesion G protein-coupled receptors (aGPCRs). Through its extracellular region, Lphn3 establishes heterophilic interactions for the formation of cell-cell interactions, while through its typical GPCR region it is able to couple to G proteins to modulate metabolic processes or remodel the actin cytoskeleton. The gene encoding Lphn3 has been the target of mutations associated with diseases such as cancer. The identification of somatic mutations from primary human tumor samples in one study reported the majority of mutations for Lphn3 harbored in the coding region for the conserved GAIN domain, which is the signature domain of the aGPCRs. The GAIN domain is found immediately upstream of the first transmembrane pass of all aGPCRs and is cleaved by an autoproteolysis reaction generating two regions of Lphn3 that are held together by non-covalent interactions until their transport to the membrane. So far, it is unclear how mutations identified in lung cancer tumor samples in the GAIN domain affect Lphn3 function. Therefore in this work we studied the cellular and molecular alterations of these cancer-related variants in Lphn3 as a tool to reveal unknown functions of the GAIN domain. We found that cancer-associated mutations in the GAIN domain reduced the adhesion between Lphn3 and its endogenous ligand Flrt3, as well as signaling through G13 coupling. They also modified actin cytoskeleton and vimentin remodeling and interestingly, the motile properties induced by wild-type Lphn3 were inhibited when the cancer-associated mutation in the GAIN domain was expressed. These data place the GAIN domain of Lphn3 as an important regulator in Lphn3-dependent cell motility thus extending our understanding of the cellular and molecular events linking somatic Lphn3 mutations to cancer-related mechanisms

Type of Event: Master Project Presentation
Speaker: Theresa Guadalupe Azcárraga Acosta
Day: 2022-05-23, at 11:30:00 hrs.
Place: Restricted access, student and committee only
Title: Biological and transcriptomic characterization of a metastatic hepatocellular carcinoma model (Samy Met) from Fischer 344 immunocompetent rats
Abstract:

Hepatocellular carcinoma is a public health issue since currently occupies the 3rd and 2nd place in cancer mortality in Mexico and worldwide, respectively. The high mortality in this kind of cancer is due to late diagnosis and lack of effective treatments for advanced stages, where 70% of patients died due to metastasis. The current models of metastatic hepatocellular carcinoma are mostly xenografts in immunodeficient mice. These do not replicate the first steps of metastasis and do not allow the establishment of a complete and homotypic microenvironment, limiting the search for not invasive, sensitive, efficient, and accessible diagnosis methods of metastasis. In our laboratory, a new model was developed based on the transplant of syngeneic cells from metastatic hepatocellular carcinoma (Samy Met) in Fischer 344 immunocompetent rats. This model should faithfully reproduce the biology of the metastatic disease, and the goal of this project is the biological and transcriptomic study of this model, and its comparation with a no metastatic model (Samy NM) in order to identify new potential metastasis biomarkers. First, the orthotopic route was selected as the route of administration which allowed to obtain metastasis and a clear difference between both phenotypes (metastatic and no metastatic). Later, both cell lines Samy Met and Samy NM were cloned, and it was determined the tumorigenic and metastatic capability of each clone to select the clones that better represent the looking phenotype. The selected clones are being evaluated in diverse biological characteristics, and mRNAs and lncRNAs sequencing will be performed. The sequencing data obtained will be analyzed with bioinformatic tools to characterize the transcriptome of each model and to find potential candidates of metastasis biomarkers

Type of Event: Seminarios de Presentación de Proyectos de Maestría
Speaker: Iván Ulises Flores Alonso
Day: 2022-05-24, at 11:30:00 hrs.
Place: estricted access, student and committee only
Title: Effects produced by a truncated Tau variant on the in vitro differentiation of SH-SY5Y neuroblastoma cells
Abstract:

In Alzheimer´s disease (AD), Tau protein, which is normally a microtubule stabilizer, aggregates abnormally in the soma of neurons as a result of several post-translational modifications. Although its abnormal hyperphosphorylation is the main cause of Tau abnormalities, proteolytic processing of the molecule also appear to increase its pathological properties of self-aggregation and toxicity. It was recently discovered that proteolytic cleavage at aspartic acid 314, caused by Caspase-2, produces two Tau fragments referred to as Tau1-314 and Tau315-441. The carboxyl-terminus fragment of Tau, Tau315-441, had the capability to abnormally invade the nuclear compartment when expressed in neuroblastoma cells. Our laboratory has studied the pathological consequences of the presence of this fragment in the nucleus, and, by performing proteomic analysis studies in transfected neuroblastoma cells, a decrease in the expression of several proteins, including some that are localized in the nucleus, participating in the stability of this structure and regulation of gene expression, as well as some associated with the cytoskeleton. On the other hand, in AD brains, healthy and affected neurons attempt to create new connections to compensate the loss of important neuronal pathways affected by cell death. To doing so, some neurons undergo neuritogenesis, involving the expression and redistribution of proteins associated with the dynamic of the cytoskeleton and synaptic communication. However, this process is not always functional and effective, and neuronal processes show abnormal plasticity developing aberrant sprouting of axonal terminals. Based on the previous information, we have hypothesized that, if the truncated Tau315-441 variant occurs and distributes to the nuclei in AD affected neurons, this could alter the expression of essential proteins involved in the processes of neuritogenesis and contribute to the process of aberrant plasticity. To test this hypothesis in vitro, in this work we evaluate the effect of the exogenous expression of Tau315-441 on the neuritogenesis and differentiation of SH-SY5Y neuroblastoma cells induced by stimulation with retinoic acid (RA) and brain-derived neurotrophic factor (BDNF). So far, we have been standardizing and characterizing this cell model, to evaluate the cytotoxic effects of this truncated Tau variant the near future. After probing several experimental conditions, we were able to find cell cultures in which SH-SY5Y cells show a phenotypic profile displaying neuritic projections from the soma, suggesting the onset of a differentiation process. It is now necessary to biochemically corroborate the expression of several markers of neuronal differentiation to be ready to evaluate the effects of truncated Tau on this relevant process

Type of Event: Master Project Presentation
Speaker: Montserrat Gutiérrez Soto
Day: 2022-05-24, at 12:00:00 hrs.
Place: Restricted access, student and committee only
Title: Identification of receptor on goblet cells for Pic protein from EAEC by in silico and in vitro assays
Abstract:

Enteroaggregative Escherichia coli is associated with acute diarrhea in children, persistent diarrhea in children and immunodeficient persons, and traveler’s diarrhea. Among its main virulence factors is an autotransporter protein termed Pic, which plays an important role during the colonization of the host intestinal epithelium. Recently, it was reported that Pic has dual activity as a mucin secretagogue in goblet cells, independent of its serine protease motif, and as a mucinase, which is dependent on its serine protease motif. In that work, the molecular mechanism for the rapid secretion of mucins that is related to the PLC/DAG-IP3/Calcium pathway was also described. However, the goblet cell receptor that binds Pic to trigger the PLC signaling pathway is so far unknown. Therefore, we consider it important to determine which is the receptor that triggers the signaling pathway for mucin secretion in goblet cells when stimulated with the Pic protease, as well as which is the motif sequence in Pic that recognizes such receptor. To determine this, we will first carry out molecular couplings with candidate receptors that might bind to Pic and thus also know in which motifs of the Pic sequence these receptors bind. Subsequently, we deleted the Pic subdomains that were identified to bind to the receptors, to test these mutants in goblet cell mucin secretion assays. Additionally, candidate receptors will be blocked using known antagonists during the mucin secretion assays induced by Pic. This strategy will allow us to identify the receptor of the PLC pathway recognized by Pic, as well as the Pic motif sequence that it uses as a ligand for its receptor, to carry out its function as a mucin secretagogue

Type of Event: Master Project Presentation
Speaker: Fernando Machado Bistraín
Day: 2022-05-25, at 11:30:00 hrs.
Place: Restricted access, student and committee only
Title: EXPRESSION OF TAF5, TAF6, AND TAF15 SUBUNITS OF THE TFIID COMPLEX, AND TAF5L AND TAF6L OF THE SAGA AND PCAF COMPLEXES DURING THE PROLIFERATION AND DIFFERENTIATION OF RCE1(5T5) CELLS
Abstract:

Corneal epithelial cell differentiation is controlled by a partially non- characterized and complex transcriptional network. Evidence suggests that the transcription factor Pax6 directs the differentiation program. Considering that the expression of TBP-associated Transcription Factors (TAFs) varies during embryonic development and during differentiation, it is of interest to study the changes in the expression of TAF5, TAF5L, TAF6, TAF6L, and TAF15 transcription factors. Therefore, we are analyzing the participation of these factors in the differentiation of RCE1(5T5) cells, which constitute an in vitro model to study the differentiation of the corneal epithelium. By analyzing the transcriptome of three stages of RCE1(5T5) cell differentiation we found that the expression of these TAFs decreases when cells reach terminal differentiation. The alignment of the messengers that encode these proteins showed that the human and rabbit sequences share an identity above 90%. On the other hand, we have designed probes to analyze by RT-qPCR the changes in the expression of these messengers throughout the differentiation process

Type of Event: Master Project Presentation
Speaker: Kevin Antonio Pérez Zaragoza
Day: 2022-05-26, at 15:00:00 hrs.
Place: Restricted access, student and committee only
Title: Participation of TLR-4 in the migration and invasion of the breast cancer cell line MDA-MB-231 stimulated with linoleic acid
Abstract:

Breast cancer is the most common malignant tumor and the leading cause of cancer death in women in Mexico and throughout the world. Epidemiological studies suggest a strong association between high levels of dietary fat intake and an increased risk of developing breast cancer. Linoleic acid (LA) is an omega-6 essential fatty acid and the main fatty acid in Western diets. In breast cancer cells, LA induces proliferation, migration, and invasion. Toll-like receptors (TLRs) are evolutionarily conserved membrane recognition sensors typical of innate immunity that recognize features present on the surface of pathogens or that are released by necrotic tissue. However, several studies show that TLR-4 is overexpressed in breast cancer cells, as well as that the overexpression of TLR-4 in tumor tissue is related to lymph node metastasis. Therefore, it is suggested that TLR-4 plays an important role in breast cancer metastasis. The objective of this work is to study the participation of the TLR-4 receptor in the processes of migration and invasion induced by LA in MDA-MB-231 breast cancer cells.

Type of Event: Master Project Presentation
Speaker: Petra Lizbeth Segura Landa
Day: 2022-05-27, at 10:00:00 hrs.
Place: Restricted access, student and committee only
Title: Impact of autoproteolysis on the G-protein coupling profile of the latrophilin-3 adhesion GPCR
Abstract:

The G-protein-coupled adhesion receptors (aGPCRs) have a long extracellular fragment NTF containing several protein-protein adhesion domains. Also, these receptors include an autoproteolysis site within a GAIN domain that encompasses the GPS cleavage site, generating a CTF fragment characterized by seven transmembrane domains interconnected by extra- and intracellular loops. Members of aGPCRs called Latrophilins (Lphns) present three isoforms (Lphn1, Lphn2, and Lphn3), with higher expression in the brain where they participate in the formation of synapses and intercellular adhesion. Lphn3 stands out for being involved in neurodevelopmental disorders. However, the importance of autoproteolysis in the G protein-coupling pathway that could be activated in this receptor is unknown. In this project, we will use targeted mutagenesis to modify the GPS cleavage site to generate a non-cleavable mutant of Lphn3. Subsequently, the impact of the mutation on the functional coupling profile between Lphn3 and several G-protein families will be analyzed using bioluminescence resonance energy transfer (BRET)-based biosensors. These will help understand the biological role of autoproteolysis in intracellular signaling processes mediated by aGPCRs

Type of Event: Master Project Presentation
Speaker: Janik Adriana Tomás Morales
Day: 2022-05-27, at 13:00:00 hrs.
Place: Restricted access, student and committee only
Title: PI3P present in Rab11+ endosomes is essential for the activation of Rab27B and the secretion of chemotactic and angiogenic factors promoted by CaSR
Abstract:

The calcium-sensing receptor (CaSR) is a G protein-coupled receptor (GPCR). The interaction with different G proteins permits CaSR participation in multiple biological processes, including secretion events. The CaSR, as other GPCRs, undergoes regulatory processes through intracellular trafficking in Rab11-coated vesicles. Vesicular trafficking is described as a process tightly coordinated, in which different molecules such as Rab GTPases and phosphoinositides will confer distinctive characteristics to vesicles. Phosphatidylinositol 3-phosphate (PI3P) is the characteristic phosphoinositide of early and sorting endosomes, which is generated mostly by the action of VPS34, a class III phosphatidylinositol 3-kinase (PI3K), and by the participation of PI3K-C2α, class II PI3K. The latter only produces 20% of PI3P in endosomes but is essential in the recruitment and activation of Rab11. The presence of PI3P at the vesicles engage proteins with FYVE and PX domains to the endosomes. Even though, endosomes Rab11+ are destined for slow recycling pathways, in our laboratory, we have demonstrated that they also have been associated with secretory pathways. Nevertheless, PI3P has been related to the activation of certain Rab GTPases, its link with secretory pathways characterized by Rab27B, which has been related to the secretion of chemotactic and angiogenic factors promoted by CaSR, is still unknown. This work aims to evaluate PI3P participation in Rab11+ endosomes in the promotion of secretory pathways defined by Rab27B

Exams

Type of Event: Final Doctoral Examination
Speaker: MSc. Ana Lilia Moreno Salinas
Day: 2022-05-11, at 11:00:00 hrs.
Place: Restricted access, student and committee only
Title: Identification of a molecular axis of pathogenicity given by signaling defects in the G13 pathway as a result of the alteration of the Lphn3 receptor by variants associated with Attention Deficit Hyperactivity Disorder
Abstract:

The latrophilins family (Lphn/ADGRL) is part of the adhesion G protein-coupled receptors (aGPCRs) that are crucial elements in the cell adhesion process. Lphn3 has become particularly relevant due to its strong association with psychiatric diseases. Lphn3 participates in the regulation of the formation and maintenance of neuronal synapses through intermolecular interactions with its ligands. Various ADHD-related Polymorphisms in Lphn3 have been reported; however, it is unknown how these alterations might affect receptor functions. In this study, functional validation of different ADHD-associated Lphn3 variants that affect receptor structure was performed. The results show an impairment in the ability of the variants to stabilize intercellular adhesion contacts in a ligand-specific manner without affecting ligand-receptor interaction parameters, which points to an alteration in the intrinsic signaling properties. Through the use of biosensors to evaluate signaling, we found an affectation given by the variants in the Gα13 pathway. Additionally, the actin remodeling functions, as well as the signaling towards RhoA shown by Lphn3 under normal conditions, were affected in the presence of specific variants. In summary, the results obtained point to a selective signaling defect in the Gα13 pathway as a result of ADHD-related variants and highlight the interaction between the GPCR functions of Lphn3 and the actin cytoskeleton in the modulation of signals during neurodevelopment related to ADHD etiology

Type of Event: Final Doctoral Examination
Speaker: M.Sc. Monserrat Avila Zozaya
Day: 2022-07-14, at 10:00:00 hrs.
Place: Restricted access, student and committee only
Title: Study of the cancer-related pathophysiological function of the GAIN domain of Lphn3 in HEK293 cells
Abstract:

Latrophilin 3 (Lphn3/ADGRL3) is an adhesion G protein-coupled receptor (aGPCR) that participates in adhesion processes through the establishment of protein-protein interactions, and in signaling processes through its coupling to G proteins. Lphn3 is predominantly expressed in the central nervous system; however, its expression has also been detected in other tissues. The gene encoding Lphn3 has been targeted by mutations related to diseases such as cancer. In a massive sequencing study of human primary tumor samples, somatic mutations for Lphn3 were identified. Most of these mutations were harbored in the coding region for the GAIN domain, which is the signature domain of the aGPCRs. The GAIN domain is the most conserved region among the aGPCRs so its function is a crucial element in understanding the physiology of Lphn3. So far, it is not clear how mutations identified in lung cancer tumor samples in the GAIN domain affect Lphn3 function. Therefore in this work we studied the cellular and molecular alterations of K561N, A760G, D798H, S810L y E811Q variants as a tool to reveal unknown functions of the GAIN domain. What we found was that the mutations reduced the adhesion between Lphn3 with its endogenous ligand Flrt3, as well as signaling through coupling to Gα13. They also modified actin cytoskeleton and vimentin remodeling and interestingly, the motile properties induced by wild-type Lphn3 were inhibited when the S810L mutation was expressed. These data situate the GAIN domain of Lphn3 as an important regulator in Lphn3-dependent cell motility thus broadening our understanding of the cellular and molecular events in which this domain might be involved

Type of Event: M.Sc. EXAMINATION
Speaker: I.B. Theresa Guadalupe Azcárraga Acosta
Day: 2022-07-22, at 10:00:00 hrs.
Place: Restricted access, student and committee only
Title: Biological and transcriptomic characterization of a metastatic hepatocellular carcinoma model (Samy Met) from Fischer 344 immunocompetent rats
Abstract:

About 70% of patients with hepatocellular carcinoma (HCC) die of metastases, mainly in the lung, due in part to late diagnosis. Therefore, it is important to find in vivo models that are representative of HCC biology in patients, allowing the development of new methods of metastasis diagnostic that are efficient and accessible. In this project, the aim is to compare the biology of a metastatic model (Samy Met) with a non-metastatic model (Samy NM) of HCC from Fischer 344 rats. First, orthotopic transplantation was selected as the best administration route since it allowed to obtain metastases and a clear difference between the phenotypes of both models. Inter-replicate variations were found in the magnitude of tumorigenic and metastatic capacity in both cell lines. This was considered to be due to the heterogeneity of the cell lines that were not from clonal origin, so it was decided to clone them. Based on their behavior in tumorigenic assays, Samy MetS E6 and Samy NM 3 were selected as the metastatic and non-metastatic models, respectively. Later, various biological characteristics of both clones were evaluated, such as proliferation, self-renewal capacity, and cancer stem cells (CSC) markers expressed. Samy MetS E6 had 99% of CD90 positive cells, a CSC marker associated with metastasis, which coincides with the high metastatic capacity of this clone. For Samy NM 3, the percentage of positive cells to stem cells markers, including CD90, was very low, which agrees with the small size of obtained tumors, as well as the absence of metastatic tumors in rats. It is concluded that both clones are an excellent tool, that will allow to do a differential expression study between a metastatic model and a non-metastatic model of HCC, this will be the base to propose new metastasis diagnostic methods and possible therapeutic targets in this project continuation

Type of Event: M.Sc. EXAMINATION
Speaker: Biol. Janik Adriana Tomás Morales
Day: 2022-07-22, at 12:00:00 hrs.
Place: Restricted access, student and committee only
Title: Endosomal PI(3)P, generated by VPS34 and PI3K-C2α, is necessary for Rab27B activation and for secretion of chemotactic factors promoted by CaSR
Abstract:

The calcium-sensing receptor (CaSR) is a G protein-coupled receptor (GPCR) that traffics intracellularly in vesicles coated with Rab11, which have been associated with secretory events. The proper coordination of vesicular trafficking requires the participation of molecules, such as Rab GTPases and phosphoinositides. Phosphatidylinositol 3-phosphate (PI(3)P) is the characteristic phosphoinositide of early and sorting endosomes; it is mainly generated by the action of VPS34, a class III phosphatidylinositol 3-kinase (PI3K); however, around 20% of PI(3)P that is produced by PI3K-C2α, a class II PI3K, is important in the recruitment and activation of effector proteins such as Rab11. Although Rab11+ endosomes are destined for slow recycling pathways, the involvement of PI(3)P in secretory events is still unknown. This work has been focused on studying the importance of PI(3)P produced from VPS34 and PI3K-C2α and its correlation in the secretion of chemotactic factors Rab27B-directed promoted by CaSR. Our results demonstrate that PI(3)P originated from class II and class III PI3K is necessary for Rab27B activation and secretion of chemotactic factors under the influence of CaSR. However, endosomal signaling appears to be more related to the PI(3)P population originated by VPS34. Therefore, this work shows the importance of PI(3)P as a possible link between slow recycling pathways and Rab27B-directed secretory pathways mediated by CaSR

Type of Event: M.Sc. EXAMINATION
Speaker: Ivan Ulises Flores Alonso
Day: 2022-07-27, at 10:00:00 hrs.
Place: Restricted access, student and committee only
Title: Standarization of in vitro differentiation of SH-SY5Y neuroblastoma cells with retinoic acid and BDNF
Abstract:

In Alzheimer`s disease (AD), Tau protein, which normally stabilizes axon microtubules, pathologically self-aggregates in the soma of neurons due to post-translational modifications (PTMs), including abnormal hyper-phosphorylation and proteolytic cleavages, which increase its aggregation properties and toxicity. It was recently discovered that Tau truncation caused by Caspase-2, at aspartic acid-314, produces two fragments: Tau1-314 and Tau315-441. The latter can invade the nucleus and decrease the expression of proteins involved in the regulation of gene expression and in the structuring of the cytoskeleton. Likewise, there is a process of compensation to neurodegeneration in AD, presenting some neuronal plasticity and neuritogenesis. Therefore, we suppose that, during the development of AD, the appearance of Tau315-441 and its abnormal redistribution may be factors that contribute to the alteration in the expression of proteins involved in neuritogenesis and neuronal plasticity. Therefore, in this work we aimed to evaluate the effect of exogenous expression of Tau315-441 on neuritogenesis and differentiation of SH-SY5Y neuroblastoma cells in vitro, induced with retinoic acid (RA) and brain-derived neurotrophic factor (BDNF). Reaching the standardization of the induction of differentiation in this cell line, allowing its use for future studies

Type of Event: Final Doctoral Examination
Speaker: M.Sc. Norma Judith Cruz Ortega
Day: 2022-07-29, at 14:00:00 hrs.
Place: Restricted access, student and committee only
Title: Study of the mechanisms involved in the remodeling of the actin cytoskeleton induced by Latrophilins 1,2 and 3
Abstract:

Latrophilins are a subgroup of the adhesion G protein-coupled receptor family, which bind to actin-associated scaffolding proteins, and they are expressed in various tissues, suggesting that they might participate in biological processes that are ubiquitous. In the present work we focus on the dynamics of the actin cytoskeleton to explore the role of latrophilins in mammalian cells. Individual overexpression of each latrophilin isoform comparably increased cell volume while modifying the net profile of F-actin-dependent cell extensions, as evaluated by confocal microscopy analysis. Deletion mutants of latrofilin evidenced that direct coupling to the intracellular machinery was a requirement for modulating actin depending cell structures. The physical interaction between latrophilins and the actin cytoskeleton was detected by co-immunoprecipitation assays and corroborated with immunocytochemistry analysis. Consistent with the destabilization of F-actin structures, latrophilin isoforms constitutively induced a prominent increase in the activity of actin depolymerizing factor, cofilin. Intercellular adhesion events stabilized by heterophilic Teneurin-4 trans-interactions disrupted latrophilin colocalization with F-actin and led to an isoform-specific rescue of cell extensions. Thus, we found that the actin cytoskeleton and associated cellular elements constitute important components of constitutive and ligand-induced signaling of latrophilins

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