Cross-sectional study using the University of California, Los Angeles, Scleroderma Clinical Trials Consortium Gastrointestinal Tract Instrument 2.0 (UCLA SCTC GIT 2.0) for gastrointestinal disorders of systemic sclerosis.

This study aimed to identify severe gastrointestinal ailments in patients with systemic sclerosis (SSc), investigate the role of antibodies in gastrointestinal disorders, and explore the relationship between limited cutaneous SSc (lcSSc) and diffuse cutaneous SSc (dcSSc) in terms of gastrointestinal involvement and its association with skin stiffness. We used the University of California, Los Angeles, Scleroderma Clinical Trials Consortium Gastrointestinal Tract Instrument 2.0 (UCLA SCTC GIT 2.0) questionnaire to assess gastrointestinal disturbances in 100 patients with SSc. Gastrointestinal impairment was categorized into three levels: absence of or minor symptoms, moderate symptoms, and severe symptoms, as indicated by the total gastrointestinal tract (GIT) score. Comparing 27 patients with dcSSc and 73 patients with lcSSc, severe gastrointestinal disturbances were found in 7.4% of patients with dcSSc and 4.1% of patients with lcSSc. A total of 18.0% of anticentromere antibody (ACA)-positive patients exhibited moderate to severe symptoms, while 9.1% of antitopoisomerase 1 antibody-positive patients displayed similar symptoms. The average disease duration in patients with severe symptoms was 15.0 years, in those with moderate symptoms was 10.3 years, and in those who were symptom-free or mildly affected was 8.5 years. Among 16 patients with moderate to severe gastrointestinal disorders, a positive correlation was observed between the modified Rodnan skin thickness score (mRSS) and total GIT score. In addition, a positive correlation was identified between fecal incontinence and mRSS, with weaker correlations for reflux and bloating symptoms. Patients with gastrointestinal disorders showed a tendency to worsen over time, particularly in ACA-positive patients with dcSSc. Furthermore, a correlation was observed between mRSS and fecal incontinence, reflux, and abdominal bloating in patients with moderate to severe gastrointestinal disturbances.

Git2 deficiency promotes MDSCs recruitment in intestine via NF-κB-CXCL1/CXCL12 pathway and ameliorates necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease in preterm infants and the most common cause of neonatal death, whereas the molecular mechanism of intestinal injury remains unclear accompanied by deficiency of effective therapeutic approaches. GIT2 (G-protein-coupled receptor kinase interacting proteins 2) can affect innate and adaptive immunity and has been involved in multiple inflammatory disorders. In this study, we investigated whether GIT2 participates in the pathogenesis of NEC. Here we found that intestinal Git2 gene expression was significantly increased in NEC patients and NEC mice, which positively correlated with the tissue damage severity, and Git2 deficiency could potently protect against NEC development in mice. Mechanistically, Git2 gene knockout dramatically increased the recruitment of MDSCs in the intestine, and in vivo depletion of MDSCs almost completely abrogated the protective effect of Git2 deficiency on NEC. Moreover, Git2 deficiency induced MDSCs intestinal accumulation mainly relied on CXCL1/CXCL12 signaling, as evidenced by the significant increment of CXCL1 and CXCL12 levels in intestinal epithelium of Git2-/- mice and dramatically decrease of MDSCs accumulation in intestine as well as increase of NEC severity upon treatment of CXCL1/CXCL12 pathway inhibitors. In addition, Git2 deficiency induced up-regulation of CXCL1 and CXCL12 is at least partially mediated through activating NF-κB signaling. Thus, our findings suggest that GIT2 is involved in the pathogenesis of NEC, and targeting GIT2 may be a potential preventive and therapeutic approach for NEC.

Regulation of microtubule nucleation in mouse bone marrow-derived mast cells by ARF GTPase-activating protein GIT2.

Aggregation of high-affinity IgE receptors (FcϵRIs) on granulated mast cells triggers signaling pathways leading to a calcium response and release of inflammatory mediators from secretory granules. While microtubules play a role in the degranulation process, the complex molecular mechanisms regulating microtubule remodeling in activated mast cells are only partially understood. Here, we demonstrate that the activation of bone marrow mast cells induced by FcϵRI aggregation increases centrosomal microtubule nucleation, with G protein-coupled receptor kinase-interacting protein 2 (GIT2) playing a vital role in this process. Both endogenous and exogenous GIT2 were associated with centrosomes and γ-tubulin complex proteins. Depletion of GIT2 enhanced centrosomal microtubule nucleation, and phenotypic rescue experiments revealed that GIT2, unlike GIT1, acts as a negative regulator of microtubule nucleation in mast cells. GIT2 also participated in the regulation of antigen-induced degranulation and chemotaxis. Further experiments showed that phosphorylation affected the centrosomal localization of GIT2 and that during antigen-induced activation, GIT2 was phosphorylated by conventional protein kinase C, which promoted microtubule nucleation. We propose that GIT2 is a novel regulator of microtubule organization in activated mast cells by modulating centrosomal microtubule nucleation.

Creation and Validation of a Portuguese Version of the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument.

(1) Background: The UCLA GIT 2.0 questionnaire has been recognized as a feasible and reliable instrument to assess gastrointestinal (GI) symptoms in systemic sclerosis (SSc) patients and their impact on quality of life. The aim of this study was to create and validate UCLA GIT 2.0 for Portuguese patients with SSc. (2) Methods: A multi-center study was conducted enrolling SSc patients. UCLA GIT 2.0 was validated in Portuguese using reliability (internal consistency, item -total correlation, and reproducibility) and validity (content, construct, and criterion) tests. Criterion tests included EQ-5D and SF-36v2. Social-demographic and clinical data were collected. (3) Results: 102 SSc patients were included, 82.4% of them female, and with a mean sample age of 57.0 ± 12.5 years old. The limited form of SSc was present in 62% of the patients and 56.9% had fewer than five years of disease duration. Almost 60% presented with SSc-GI involvement with a negative impact on quality of life. The means for SF-36v2 were 39.3 ± 10.3 in the physical component summary and 47.5 ± 12.1 in the mental component summary. Total GI score, reported as mild in 57.8% of the patients, was highly reliable (ICC = 0.912) and the Cronbach's alpha was 0.954. There was a high correlation between the total GI score and EQ-5D-5L and SF-36v2 scores. (4) Conclusion: The Portuguese version of UCLA GIT 2.0 showed good psychometric properties and can be used in research and clinical practice.

The Relaxin-3 Receptor, RXFP3, Is a Modulator of Aging-Related Disease.

During the aging process our body becomes less well equipped to deal with cellular stress, resulting in an increase in unrepaired damage. This causes varying degrees of impaired functionality and an increased risk of mortality. One of the most effective anti-aging strategies involves interventions that combine simultaneous glucometabolic support with augmented DNA damage protection/repair. Thus, it seems prudent to develop therapeutic strategies that target this combinatorial approach. Studies have shown that the ADP-ribosylation factor (ARF) GTPase activating protein GIT2 (GIT2) acts as a keystone protein in the aging process. GIT2 can control both DNA repair and glucose metabolism. Through in vivo co-regulation analyses it was found that GIT2 forms a close coexpression-based relationship with the relaxin-3 receptor (RXFP3). Cellular RXFP3 expression is directly affected by DNA damage and oxidative stress. Overexpression or stimulation of this receptor, by its endogenous ligand relaxin 3 (RLN3), can regulate the DNA damage response and repair processes. Interestingly, RLN3 is an insulin-like peptide and has been shown to control multiple disease processes linked to aging mechanisms, e.g., anxiety, depression, memory dysfunction, appetite, and anti-apoptotic mechanisms. Here we discuss the molecular mechanisms underlying the various roles of RXFP3/RLN3 signaling in aging and age-related disorders.

Performance of the UCLA Scleroderma Clinical Trials Consortium Gastrointestinal Tract 2.0 instrument as a clinical decision aid in the routine clinical care of patients with systemic sclerosis.

BACKGROUND AND OBJECTIVES: The University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument 2.0 (UCLA GIT 2.0) is validated to capture gastrointestinal (GI) tract morbidity in patients with systemic sclerosis (SSc). The aims of this study were to determine in a large SSc cohort if the UCLA GIT 2.0 is able to discriminate patients for whom a rheumatologist with experience in SSc would recommend an esophago-gastro-duodenoscopy (EGD), and if it could identify patients with endoscopically proven esophagitis or with any pathologic finding on EGD. METHODS: We selected patients fulfilling the ACR/EULAR 2013 criteria for SSc from our EUSTAR center having completed at least once the UCLA GIT 2.0 questionnaire, and we collected data on gastrointestinal symptoms and EGD from their medical charts. We analyzed by general linear mixed effect models several parameters, including UCLA GIT 2.0, considered as potentially associated with the indication of EGD, as well as with endoscopic esophagitis and any pathologic finding on EGD. RESULTS: We identified 346 patients (82.7% female, median age 63 years, median disease duration 10 years, 23% diffuse cutaneous SSc) satisfying the inclusion criteria, who completed UCLA GIT 2.0 questionnaires at 940 visits. EGD was recommended at 169 visits. In multivariable analysis, UCLA GIT 2.0 and some of its subscales (reflux, distention/bloating, social functioning) were associated with the indication of EGD. In 177 EGD performed in 145 patients, neither the total ULCA GIT 2.0 score nor any of its subscales were associated with endoscopic esophagitis, nor with any pathologic EGD findings. CONCLUSIONS: In a real-life setting, the UCLA GIT 2.0 and its reflux subscale were able to discriminate patients with SSc who had an indication for EGD, but did not correlate with findings in EGD. We conclude that, while using the UCLA GIT 2.0 in the routine care of patients with SSc may help the rheumatologist to better understand the burden of GI symptoms in the individual patient, it should not be used as a stand-alone instrument to identify an indication of EGD.

Long non-coding RNA MALAT1 promotes odontogenic differentiation of human dental pulp stem cells by impairing microRNA-140-5p-dependent downregulation of GIT2.

Accumulating research continues to highlight the notable role of microRNAs (miRs) and long non-coding RNAs (lncRNAs) as important regulators in the process of human dental pulp stem cell (hDPSCs) differentiation. The current study aimed to investigate the novel regulatory circuitry of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/miR-140-5p/G protein-coupled receptor (GPCR)-kinase 2 interacting protein 2 (GIT2) on the odontogenic differentiation of hDPSCs. In hDPSCs, miR-140-5p was downregulated during the odontogenic differentiation, which was verified to directly target GIT2. RNA crosstalk determined by dual-luciferase reporter and RNA pull-down assays revealed that MALAT1 could bind to miR-140-5p to upregulate the expression of GIT2. After that, the levels of MALAT1, miR-140-5p, and GIT2 in hDPSCs were up- or downregulated by exogenous transfection or lentivirus infection in order to investigate their effects on the differentiation of hDPSCs. It was observed that elevation of miR-140-5p or knockdown of GIT2 resulted in inhibited alkaline phosphatase (ALP) activity, expression of dentin sialophosphoprotein (DSPP), dentin matrix-protein-1 (DMP-1), and distal-less homeobox 3 (DLX3) as well as positive expression of desmoplakin (DSP) protein. The promotive effects of MALAT1 on odontogenic differentiation were diminished by restoration of miR-140-5p or inhibition of GIT2. Taken together, this study provides valuable evidence suggesting MALAT1 as a potential contributor to the odontogenic differentiation of hDPSCs.

Multidimensional informatic deconvolution defines gender-specific roles of hypothalamic GIT2 in aging trajectories.

In most species, females live longer than males. An understanding of this female longevity advantage will likely uncover novel anti-aging therapeutic targets. Here we investigated the transcriptomic responses in the hypothalamus - a key organ for somatic aging control - to the introduction of a simple aging-related molecular perturbation, i.e. GIT2 heterozygosity. Our previous work has demonstrated that GIT2 acts as a network controller of aging. A similar number of both total (1079-female, 1006-male) and gender-unique (577-female, 527-male) transcripts were significantly altered in response to GIT2 heterozygosity in early life-stage (2 month-old) mice. Despite a similar volume of transcriptomic disruption in females and males, a considerably stronger dataset coherency and functional annotation representation was observed for females. It was also evident that female mice possessed a greater resilience to pro-aging signaling pathways compared to males. Using a highly data-dependent natural language processing informatics pipeline, we identified novel functional data clusters that were connected by a coherent group of multifunctional transcripts. From these it was clear that females prioritized metabolic activity preservation compared to males to mitigate this pro-aging perturbation. These findings were corroborated by somatic metabolism analyses of living animals, demonstrating the efficacy of our new informatics pipeline.

GIT2 deficiency attenuates inflammation-induced expression of pro-labor mediators in human amnion and myometrial cells†.

Untimely activation of the inflammatory response by sterile or infective insults in uterine tissues can result in preterm birth. Pro-inflammatory cytokines and pathogenic activation of toll-like receptors (TLRs) initiate a biochemical cascade of events leading to myometrial activation and contractility, cervical dilatation, and rupture of the chorioamniotic membranes. GIT2 is a signaling protein known to play a role in innate and adaptive immunity; however, its role in the inflammatory pathways of human labor is not known. In this article, we report that GIT2 expression is lower in human myometrium and fetal membranes with term labor, and in preterm amnion with histological chorioamnionitis. GIT2 knockdown by siRNA in primary myometrial and amnion cells exhibited reduced expression of pro-inflammatory cytokines and chemokines in response to inflammatory challenge by cytokines or TLR ligands. In addition, the pro-inflammatory cytokines IL1B and TNF could not induce the expression of extracellular matrix degrading enzymes in GIT2-deficient amnion cells. Myometrial activation in response to pro-inflammatory cytokines was also significantly suppressed in GIT2-deficient cells as evidenced by decreased prostaglandin release and expression of contraction-associated proteins. Further to this, collagen gel assays demonstrated that TNF had a reduced ability to induce myometrial contractility in situ in GIT2-deficient myometrial cells compared to control-transfected cells. In summary, the loss of GIT2 diminishes the effects inflammatory mediators have in promoting myometrial contraction and fetal membrane rupture in vitro, suggesting that GIT2 could be a possible target for preterm birth therapies.

G Protein-Coupled Receptor Systems and Their Role in Cellular Senescence.

Aging is a complex biological process that is inevitable for nearly all organisms. Aging is the strongest risk factor for development of multiple neurodegenerative disorders, cancer and cardiovascular disorders. Age-related disease conditions are mainly caused by the progressive degradation of the integrity of communication systems within and between organs. This is in part mediated by, i) decreased efficiency of receptor signaling systems and ii) an increasing inability to cope with stress leading to apoptosis and cellular senescence. Cellular senescence is a natural process during embryonic development, more recently it has been shown to be also involved in the development of aging disorders and is now considered one of the major hallmarks of aging. G-protein-coupled receptors (GPCRs) comprise a superfamily of integral membrane receptors that are responsible for cell signaling events involved in nearly every physiological process. Recent advances in the molecular understanding of GPCR signaling complexity have expanded their therapeutic capacity tremendously. Emerging data now suggests the involvement of GPCRs and their associated proteins in the development of cellular senescence. With the proven efficacy of therapeutic GPCR targeting, it is reasonable to now consider GPCRs as potential platforms to control cellular senescence and the consequently, age-related disorders.

G Protein-Coupled Receptor Systems as Crucial Regulators of DNA Damage Response Processes.

G protein-coupled receptors (GPCRs) and their associated proteins represent one of the most diverse cellular signaling systems involved in both physiological and pathophysiological processes. Aging represents perhaps the most complex biological process in humans and involves a progressive degradation of systemic integrity and physiological resilience. This is in part mediated by age-related aberrations in energy metabolism, mitochondrial function, protein folding and sorting, inflammatory activity and genomic stability. Indeed, an increased rate of unrepaired DNA damage is considered to be one of the 'hallmarks' of aging. Over the last two decades our appreciation of the complexity of GPCR signaling systems has expanded their functional signaling repertoire. One such example of this is the incipient role of GPCRs and GPCR-interacting proteins in DNA damage and repair mechanisms. Emerging data now suggest that GPCRs could function as stress sensors for intracellular damage, e.g., oxidative stress. Given this role of GPCRs in the DNA damage response process, coupled to the effective history of drug targeting of these receptors, this suggests that one important future activity of GPCR therapeutics is the rational control of DNA damage repair systems.

Genetic deletion of GIT2 prolongs functional recovery and suppresses chondrocyte differentiation in rats with rheumatoid arthritis.

The current study was conducted for investigating the mechanism by which GIT2 gene deletion affects the functional recovery and chondrocyte differentiation in rats with rheumatoid arthritis (RA). Thirty-two rats were randomly divided into normal, model, GIT2 gene knockout (GIT2-KO), and model + GIT2-KO groups. Hematoxylin-eosin (HE) staining was performed for the observation of synovial tissues. Immunohistochemistry examinations were conducted to determine type II collagen expression as well as identify chondrocyte differentiation. qRT-PCR and Western blotting techniques were adopted in order to expressions of interleukin-1ß (1L-1ß), tumor necrosis factor-α (TNF-α), Aggrecan, and Sry-related HMG box 9 (Sox9). A tape measure and Vernier caliper were used to measure the degree of swelling. Compared with synovial tissues in the model group, those in the model + GIT2-KO group, were thicker and comprised of a mass of inflammatory cells (P < 0.05). Compared with the model group, the type II collagen expressions of the cartilage tissues of the rats decreased in the model + GIT2-KO group (P < 0.05). In terms of the degree of swelling in cartilage tissues, the model group displayed a lesser degree of swelling than in that of the model + GIT2-KO group (P < 0.05). When compared with the model + GIT2-KO group, the mRNA expressions of 1L-1ß, TNF-α, Aggrecan, Sox9 and the relevant protein expressions were lower in the model group (all P < 0.05). GIT2 gene deletion might weaken chondrocyte differentiation in rats with RA, as a result acting to ultimately prolong the functional recovery of RA.

A novel GIT2-BRAF fusion in pilocytic astrocytoma.

BACKGROUND: KIAA1549-BRAF fusion is the most common genetic event in pilocytic astrocytoma (PA), and leads to activation of the mitogen activated protein kinase (MAPK) signaling pathway. Fusions of BRAF with other partner genes, as well as other genetic alterations not involving BRAF but also leading to MAPK pathway activation have been described rarely. CASE PRESENTATION: We present a new fusion partner in the low-grade glioma of a 10-year-old male, who presented with headaches and recent episodes of seizures. Magnetic resonance imaging (MRI) demonstrated a right temporal lobe tumor. Histological and immunohistochemical evaluation, and a next generation sequencing assay (Oncopanel, Illumina, 500 genes) including breaKmer analysis for chromosomal rearrangements were performed. Histology was remarkable for a low-grade glioma composed of mildly atypical astrocytes with piloid processes, in a focally microcystic background. Mitoses were not seen; unequivocal Rosenthal fibers or eosinophilic granular bodies were absent. The tumor was positive for OLIG2 and GFAP and negative for BRAF V600E and IDH1 R132H mutant protein immunostains. Oncopanel showed low SOX2 (3q26.33) copy number gain, and no gains at 7q34. There were no significant single nucleotide variants. BreaKmer detected a GIT2-BRAF fusion with loss of BRAF exons 1-8. The integrated diagnosis was low-grade glioma with piloid features, most consistent with pilocytic astrocytoma, WHO grade I. CONCLUSION: GIT2-BRAF fusion has not been reported in the literature in any tumor. Given that the BRAF sequence deleted is identical to that seen in other fusion events in PA, it most likely acts as tumor driver by activation of the MAPK pathway.

[High-Content siRNA Screen of the Kinome Identifies Kinases Involved in Git2-Induced Mesenchymal-Epithelial Transition].

Epithelial-mesenchymal transition (EMT) and its reverse process mesenchymal-epithelial transition (MET) programs are involced in the metastatic process. More and more evidence confirms that EMT is vital for the initiation and dissemination of cancer cells whereas MET is critical for successful metastatic colonization of a secondary organ. The regulating mechanism of EMT mediated cancer progression and metastasis has been deeply investigated. However, what processes are dependent on MET in metastatic cascades remains unclear. Here, we created a cell based high-content siRNA screen using the breast cancer cell line 4TO7 to search for kinases that were involved in Git2-induced MET. Our results revealed that 58 kinases including transferase, phosphorylation regulators, ATP/nucleotide partners potentially participate in Git2-induced MET. Our preliminary data is expected to facilitate elucidation of the mechanism on how MET is initiated during cancer metastasis.

Validation of Serbian version of UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument in 104 patients with systemic sclerosis.

Gastrointestinal (GI) involvement is the leading cause of morbidity with great impact on health-related quality of life (HRQOL) in patients with systemic sclerosis (SSc). The UCLA-GIT 2.0 is a disease-specific HRQOL instrument for the assessment of GI symptoms severity in patients with SSc. We evaluated reliability and validity of the Serbian version of UCLA-GIT 2.0 by assessing association of GI involvement and other disease manifestations in patients with SSc. UCLA-GIT 2.0 was adapted into Serbian and administered to 104 patients with SSc who had previously completed the SF-36 questionnaire. We evaluated the internal consistency reliability and associations between the UCLA-GIT 2.0 and SF-36 scales. Data from patients' medical history were reviewed for other disease manifestations. UCLA-GIT 2.0 had acceptable reliability (defined as Cronbach's alpha >0 .69) and the majority of hypothesized correlations with SF-36 scale scores were of moderate magnitude (coefficient ≥ 0.30). Active disease and pulmonary fibrosis were associated with higher GIT Total scale score (p < 0.05). Distension mostly correlated with HRQOL impairment (r = 0.70, p < 0.001). The Serbian version of the UCLA-GIT 2.0 questionnaire has acceptable reliability and validity for the assessment of GI involvement in patients with SSc. GI impairment is very frequent in patients with active SSc, as well in those with pulmonary fibrosis.

Genomic deletion of GIT2 induces a premature age-related thymic dysfunction and systemic immune system disruption.

Recent research has proposed that GIT2 (G protein-coupled receptor kinase interacting protein 2) acts as an integrator of the aging process through regulation of 'neurometabolic' integrity. One of the commonly accepted hallmarks of the aging process is thymic involution. At a relatively young age, 12 months old, GIT2-/- mice present a prematurely distorted thymic structure and dysfunction compared to age-matched 12 month-old wild-type control (C57BL/6) mice. Disruption of thymic structure in GIT2-/- (GIT2KO) mice was associated with a significant reduction in the expression of the cortical thymic marker, Troma-I (cytokeratin 8). Double positive (CD4+CD8+) and single positive CD4+ T cells were also markedly reduced in 12 month-old GIT2KO mice compared to age-matched control wild-type mice. Coincident with this premature thymic disruption in GIT2KO mice was the unique generation of a novel cervical 'organ', i.e. 'parathymic lobes'. These novel organs did not exhibit classical peripheral lymph node-like characteristics but expressed high levels of T cell progenitors that were reflexively reduced in GIT2KO thymi. Using signaling pathway analysis of GIT2KO thymus and parathymic lobe transcriptomic data we found that the molecular signaling functions lost in the dysfunctional GIT2KO thymus were selectively reinstated in the novel parathymic lobe - suggestive of a compensatory effect for the premature thymic disruption. Broader inspection of high-dimensionality transcriptomic data from GIT2KO lymph nodes, spleen, thymus and parathymic lobes revealed a systemic alteration of multiple proteins (Dbp, Tef, Per1, Per2, Fbxl3, Ddit4, Sin3a) involved in the multidimensional control of cell cycle clock regulation, cell senescence, cellular metabolism and DNA damage. Altered cell clock regulation across both immune and non-immune tissues therefore may be responsible for the premature 'aging' phenotype of GIT2KO mice.

Expanding functions of GIT Arf GTPase-activating proteins, PIX Rho guanine nucleotide exchange factors and GIT-PIX complexes.

The GIT proteins, GIT1 and GIT2, are GTPase-activating proteins (inactivators) for the ADP-ribosylation factor (Arf) small GTP-binding proteins, and function to limit the activity of Arf proteins. The PIX proteins, α-PIX and ß-PIX (also known as ARHGEF6 and ARHGEF7, respectively), are guanine nucleotide exchange factors (activators) for the Rho family small GTP-binding protein family members Rac1 and Cdc42. Through their multi-domain structures, GIT and PIX proteins can also function as signaling scaffolds by binding to numerous protein partners. Importantly, the constitutive association of GIT and PIX proteins into oligomeric GIT-PIX complexes allows these two proteins to function together as subunits of a larger structure that coordinates two distinct small GTP-binding protein pathways and serves as multivalent scaffold for the partners of both constituent subunits. Studies have revealed the involvement of GIT and PIX proteins, and of the GIT-PIX complex, in numerous fundamental cellular processes through a wide variety of mechanisms, pathways and signaling partners. In this Commentary, we discuss recent findings in key physiological systems that exemplify current understanding of the function of this important regulatory complex. Further, we draw attention to gaps in crucial information that remain to be filled to allow a better understanding of the many roles of the GIT-PIX complex in health and disease.

EGF-stimulated activation of Rab35 regulates RUSC2-GIT2 complex formation to stabilize GIT2 during directional lung cancer cell migration.

Non-small cell lung cancer (NSCLC) remains one of the most metastasizing tumors, and directional cell migration is critical for targeting tumor metastasis. GIT2 has been known to bind to Paxillin to control cell polarization and directional migration. However, the molecular mechanisms underlying roles of GIT2 in controlling cell polarization and directional migration remain elusive. Here we demonstrated GIT2 control cell polarization and direction dependent on the regulation of Golgi through RUSC2. RUSC2 interacts with SHD of GIT2 in various lung cancer cells, and stabilizes GIT2 (Mazaki et al., 2006; Yu et al., 2009) by decreasing degradation and increasing its phosphorylation. Silencing of RUSC2 showed reduced stability of GIT2, defective Golgi reorientation toward the wound edge and decreased directional migration. Moreover, short-term EGF stimulation can increase the interaction between RUSC2 and GIT2, prolonged stimulation leads to a decrease of their interaction through activating Rab35. Silencing of Rab35 also reduced stability and phosphorylation of GIT2 and decreased cell migration. Taken together, our study indicated that RUSC2 participates in EGFR signaling and regulates lung cancer progression, and may be a new therapeutic target against lung cancer metastasis.

Effectiveness and safety of oxycodone/naloxone in the management of chronic pain in patients with systemic sclerosis with recurrent digital ulcers: two case reports.

Digital ulcers (DUs) are a severe and frequent clinical feature of patients with systemic sclerosis (SSc). The presence of DUs may cause severe pain and often lead to impairment of patient's functional activities and health-related quality of life. Moreover, poor patient cooperation during the wound care procedure due to pain may be associated with a negative outcome of DU healing. Therefore, pain management has a key role in patients with SSc. These two case reports describe the effectiveness and safety of oxycodone/naloxone in patients with SSc complicated by painful chronic DUs. Such a therapy has provided pain relief and consequently an increased compliance during redressing wounds.

GIT2 deficiency attenuates concanavalin A-induced hepatitis in mice.

G protein-coupled receptor kinase interactor 2 (GIT2) is a signaling scaffold protein involved in regulation of cytoskeletal dynamics and the internalization of G protein-coupled receptors (GPCRs). The short-splice form of GIT2 is expressed in peripheral T cells and thymocytes. However, the functions of GIT2 in T cells have not yet been determined. We show that treatment with Con A in a model of polyclonal T-lymphocyte activation resulted in marked inhibitions in the intrahepatic infiltration of inflammatory cells, cytokine response and acute liver failure in Git2 (-/-) mice. CD4(+) T cells from Git2 (-/-) mice showed significant impairment in proliferation, cytokine production and signal transduction upon TCR-stimulated activation. Our results suggested that GIT2 plays an important role in T-cell function in vivo and in vitro.