Sumoylation is an essential post-translational modification that regulates a wide range of cellular functions. Interestingly, several proteins involved in synaptic functions have been shown to be SUMO targets. Unpublished data from my current lab identified a list of SUMO substrates at the synapse. Among them, we find Protocadherin-10 (PCDH10), an autism-related cell adhesion transmembrane protein. Mice lacking one copy of Pcdh10 gene present abnormal spine density and morphology, reduced expression of NMDA receptors in the amygdala and sociability deficits. Furthermore, PCDH10 recruits ubiquitinated PSD-95 to the proteasome and promotes synapse elimination. These findings demonstrate that PCDH10 is centrally involved in the regulation of synapse density and function. However, whether the sumoylation of PCDH10 plays a role in this process remains to be elucidated. Thus, I performed a bioinformatic analysis showing that the lysine 831 (K831) of PCDH10 has a high SUMO predictive value. Interestingly, the K831 is located in the proteosomal interacting region (PIR), which is critical to allow PSD-95 degradation and, consequently, synapse elimination. Sumoylation regulates protein-protein interactions by providing novel docking sites or promoting the dissociation of the binding. Therefore, I hypothesize that sumoylation of PCDH10 is crucial for synapse elimination by regulating the interaction with the proteasome. Thus, the overall goal of my research project is to unveil the physiopathological consequences of PCDH10 sumoylation in neurons. Since synapse elimination is impaired in several neurodevelopmental disorders, I am confident that the data arising from this work will provide groundbreaking knowledge in the understanding of the molecular mechanisms underlying ID in patients carrying Pcdh10 mutations. Furthermore, uncovering the impact of sumoylation on the development of mental disorders will open up a thrilling topic in the neuroscience field.

This project is focused on the development of novel nanomedicines effective in targeting the immunosuppressive, pro-tumoural, Tumour-Associated Macrophages (TAM) with the aim to manipulate the host’s immune system and improve anti-tumour responses. In most patients, chronic inflammation and immune suppression are the dominant effects in the tumour microenvironment. The infiltration of TAM in tumour tissues has been shown to support tumour growth, invasion and metastasis. Indeed, high density of TAM in tumours is correlated with resistance to therapies and poor prognosis. These findings establish TAM as promising targets of future anti-tumour therapies. Here, we aim to design a series of Therapeutic Nanostructures (TNs), containing immunomodulatory or chemotherapeutic compounds, and conveniently functionalized, in order to target and re-educate or kill the TAM. These novel TNs will be composed of biodegradable polysaccharides, i.e. chitosan (CS) or hyaluronic acid (HA), and will be functionalized, with the aim to develop a series of “targeting” strategies to optimally reach TAM in vivo. These strategies involve the chemical linking of: (i) mannose residues expected to direct the TNs to the mannose receptors, highly expressed on the surface of TAM or (ii) the tumour lymphatic-specific peptide (LyP-1), known to have affinity towards NRP1 on TAM. The nanomedicines (TNs) will be loaded with pharmacological activators of TLR7 aimed to re-educate TAM into immunostimulatory anti-tumour macrophages. In the event that re-polarization of TAM is not satisfactory, or its effect is not long lasting in vivo, TNs will be loaded with chemotherapeutic drugs able to kill TAM. The TNs will be tested in vitro and in vivo to verify their effectiveness in switching back the pro-tumoural properties of TAM and their effect on tumour growth. We expect that this approach will enable greater progress in the treatment of tumours and ultimately lead to improved outcomes for cancer patients.

There is a fundamental gap in understanding how the GPR101 gene regulates human growth in physiological and pathological conditions. Children’s growth is remarkably clinical relevant and is an important indicator of their health and general well-being. The specific objective of this proposal is to identify the molecular mechanisms underlying GPR101 overexpression in the pituitary tumors of children with GPR101 duplications causing X-linked acrogigantism (X-LAG). My central hypothesis is that GPR101 duplications disrupt the structure of the local chromatin, leading to the creation of a new chromatin domain where de novo enhancer-promoter interactions take place, causing abnormal GPR101 expression. This hypothesis will be tested by pursuing three specific aims: 1. Elucidate the transcriptional regulation of GPR101 in normal and pathological conditions 2. Identify and functionally characterize novel pituitary-specific enhancer sequences 3. Investigate these regulatory sequences in patients with different pituitary pathologies. To achieve aim 1) I will perform an in vitro functional characterization of GPR101 promoter: promoter activity will be studied by luciferase-based reporter assays, by conducting a methylation analysis, and by determining its accessibility to transcription factors. To achieve aim 2) I will validate my preliminary results showing the formation of a novel chromatin domain by 4C-Seq. Four putative enhancer sequences located within the duplicated GPR10 region and identified in silico will be functionally evaluated in vitro to establish their impact on transcriptional activity. To identify novel pituitary-specific enhancers, a whole-genome profile of enhancer-specific histone marks will be performed in normal and tumoral pituitary cells by ChIP-Seq. To achieve aim 3) I will screen patients with different pituitary disorders for mutations (Sanger sequencing) and structural variations (CNV assays) in the functionally-verified enhancers.

The innate immune system includes a cellular and a humoral arm. Structural diversity is a characteristic of humoral fluid phase pattern recognition molecules. These include complement components, collectins, ficolins, and pentraxins. We have used the long pentraxin PTX3, identified by the applicant (cDNA and genomic, mouse and human), as a prototypic fluid phase pattern recognition molecule to dissect its function, as well as to define general properties of humoral innate immunity and its interplay with the cellular arm. The general objective of this application is to explore unexpected vistas on humoral innate immunity, using PTX3 as a molecular tool. Specifically two hypothesis will be tested based on preliminary data. First the applicant will test the hypothesis that matrix and microbe recognition are related functions of PTX3 and that a microenvironmental signal (acidic pH) sets PTX3 in a matrix recognition, tissue repair mode. A second related line of work will focus on inflammation as a key component of the tumor microenvironment. The applicant will test the hypothesis that PTX3 and elements of the humoral innate immune system are essential components of cancer related inflammation. In particular, based on preliminary data, the hypothesis will be tested that PTX3 acts as an extrinsic oncosuppressor in murine carcinogenesis and in selected human cancers by suppressing the recruitment of tumor-promoting inflammatory cells. These studies are expected to provide new unexpected vistas on the humoral arm of the innate immune system.