'Doing the hard yards': Carer and provider focus group perspectives of accessing Aboriginal childhood disability services

Background: Despite a high prevalence of disability, Aboriginal Australians access disability services in Australia less than non-Aboriginal Australians with a disability. The needs of Aboriginal children with disability are particularly poorly understood. They can endure long delays in treatment which can impact adversely on development. This study sought to ascertain the factors involved in accessing services and support for Aboriginal children with a disability. Methods. Using the focus group method, two community forums, one for health and service providers and one for carers of Aboriginal children with a disability, were held at an Aboriginal Community Controlled Health Service (ACCHS) in the Sydney, metropolitan area of New South Wales, Australia. Framework analysis was applied to qualitative data to elucidate key issues relevant to the dimensions of access framework. Independent coding consistency checks were performed and consensus of analysis verified by the entire research team, several of whom represented the local Aboriginal community. Results: Seventeen health and social service providers representing local area government and non-government-funded health and social service organisations and five carers participated in two separate forums between September and October 2011. Lack of awareness of services and inadequate availability were prominent concerns in both groups despite geographic proximity to a major metropolitan area with significant health infrastructure. Carers noted racism, insufficient or non-existent services, and the need for an enhanced role of ACCHSs and AHWs in disability support services. Providers highlighted logistical barriers and cultural and historical issues that impacted on the effectiveness of mainstream services for Aboriginal people. Conclusions: Despite dedicated disability services in an urban community, geographic proximity does not mitigate lack of awareness and availability of support. This paper has enumerated a number of considerations to address provision of disability services in an urban Australian Aboriginal community including building expertise and specialist capacity within Aboriginal Health Worker positions and services. Increasing awareness of services, facilitating linkages and referrals, eliminating complexities to accessing support, and working with families and Aboriginal community organisations within a framework of resilience and empowerment to ensure a relevant and acceptable model are necessary steps to improving support and care for Aboriginal children with a disability. © 2013 DiGiacomo et al.; licensee BioMed Central Ltd

Molecular mechanism of Gαi activation by non-GPCR proteins with a Gα-Binding and Activating motif

Heterotrimeric G proteins are quintessential signalling switches activated by nucleotide exchange on Gα. Although activation is predominantly carried out by G-protein-coupled receptors (GPCRs), non-receptor guanine-nucleotide exchange factors (GEFs) have emerged as critical signalling molecules and therapeutic targets. Here we characterize the molecular mechanism of G-protein activation by a family of non-receptor GEFs containing a Gα-binding and -activating (GBA) motif. We combine NMR spectroscopy, computational modelling and biochemistry to map changes in Gα caused by binding of GBA proteins with residue-level resolution. We find that the GBA motif binds to the SwitchII/α3 cleft of Gα and induces changes in the G-1/P-loop and G-2 boxes (involved in phosphate binding), but not in the G-4/G-5 boxes (guanine binding). Our findings reveal that G-protein-binding and activation mechanisms are fundamentally different between GBA proteins and GPCRs, and that GEF-mediated perturbation of nucleotide phosphate binding is sufficient for Gα activation

A biochemical and genetic discovery pipeline identifies PLCδ4b as a non-receptor activator of heterotrimeric G proteins

Recent evidence has revealed that heterotrimeric G proteins can be activated by cytoplasmic proteins that share an evolutionarily conserved sequence called the Gα-binding-and-activating (GBA) motif. This mechanism alternative to canonical activation by GPCRs plays important roles in cell function and its dysregulation is linked to disease such as cancer. Here we describe a discovery pipeline that uses biochemical and genetic approaches to validate GBA candidates identified by sequence similarity. First, putative GBA motifs discovered in bioinformatics searches were synthesized on peptide arrays and probed in batch for Gαi3 binding. Then, cDNAs encoding proteins with Gαi3-binding sequences were expressed in a genetically-modified yeast strain that reports mammalian G protein activity in the absence of GPCRs. The resulting GBA motif candidates were characterized by comparison of their biochemical, structural, and signaling properties with those of all previously described GBA motifs in mammals (GIV/Girdin, DAPLE, Calnuc, and NUCB2). We found that the phospholipase C δ4 (PLCδ4) GBA motif binds G proteins with high affinity, has guanine-nucleotide exchange factor activity in vitro, and activates G-protein signaling in cells, as indicated by bioluminescence resonance energy transfer (BRET)-based biosensors of G-protein activity. Interestingly, the PLCδ4 isoform b, which lacks the domains required for PLC activity, bound and activated G proteins more efficiently than the full-length isoform a, suggesting that PLCδ4b functions as a G-protein regulator rather than as a PLC. In summary, we have identified PLCδ4 as a non-receptor activator of G proteins, and established an experimental pipeline to discover and characterize GBA motif-containing proteins

Small-molecule targeting of GPCR-independent noncanonical G-protein signaling in cancer

10 p.-5 fig.Activation of heterotrimeric G-proteins (Gαβγ) by G-protein-coupled receptors (GPCRs) is a quintessential mechanism of cell signaling widely targeted by clinically approved drugs. However, it has become evident that heterotrimeric G-proteins can also be activated via GPCR-independent mechanisms that remain untapped as pharmacological targets. GIV/Girdin has emerged as a prototypical non-GPCR activator of G proteins that promotes cancer metastasis. Here, we introduce IGGi-11, a first-in-class small-molecule inhibitor of noncanonical activation of heterotrimeric G-protein signaling. IGGi-11 binding to G-protein α-subunits (Gαi) specifically disrupted their engagement with GIV/Girdin, thereby blocking noncanonical G-protein signaling in tumor cells and inhibiting proinvasive traits of metastatic cancer cells. In contrast, IGGi-11 did not interfere with canonical G-protein signaling mechanisms triggered by GPCRs. By revealing that small molecules can selectively disable noncanonical mechanisms of G-protein activation dysregulated in disease, these findings warrant the exploration of therapeutic modalities in G-protein signaling that go beyond targeting GPCRs.This work was supported by NIH grant R01GM130120 and the Karin Grunebaum Cancer Research Foundation (to M.G.-M). J.Z. was supported by a Dahod International Scholar Award, and A.L. was supported by a F31 Ruth L. Kirschstein NRSA Predoctoral Fellowship (F31NS115318). F.J.B. was supported by Spanish Government grant PID2020-113225GB-I00. M.F.-G was supported by Spanish Government fellowship PRE-2018-085788.Peer reviewe

Childhood disability in Aboriginal and Torres Strait Islander peoples: A literature review

Introduction. Aboriginal and Torres Strait Islander children have higher rates of disability than non-Indigenous children and are considered doubly disadvantaged, yet there is very little data reflecting prevalence and service access to inform design and delivery of services. Failing to address physical, social, and psychological factors can have life-long consequences and perpetuate longstanding health disparities. Methods. A narrative literature review was undertaken to identify peer reviewed literature describing factors impacting on the prevention, recognition, and access to support and management of disability in Indigenous Australian children. Results: Twenty-seven peer-reviewed journal articles met inclusion criteria. The majority of articles focused on the hearing loss and learning disabilities consequent of otitis media. Few articles reported data on urban or metropolitan Indigenous populations or described interventions. Individual/community-, provider-, and systems level factors were identified as impacting on recognition and management of disability in young Indigenous children. Conclusions: Given the burden of childhood disability, the limited literature retrieved is concerning as this is a barometer of activity and investment. Solutions addressing childhood disability will require collaboration between health, social and educational disciplines as well as an increased investment in prevention, identification and promotion of access. © 2013 DiGiacomo et al.; licensee BioMed Central Ltd

DAPLE protein inhibits nucleotide exchange on Gαs and Gαq via the same motif that activates Gαi

Besides being regulated by G-protein–coupled receptors, the activity of heterotrimeric G proteins is modulated by many cytoplasmic proteins. GIV/Girdin and DAPLE (Dvl-associating protein with a high frequency of leucine) are the best-characterized members of a group of cytoplasmic regulators that contain a Gα-binding and -activating (GBA) motif and whose dysregulation underlies human diseases, including cancer and birth defects. GBA motif–containing proteins were originally reported to modulate G proteins by binding Gα subunits of the Gi/o family (Gαi) over other families (such as Gs, Gq/11, or G12/13), and promoting nucleotide exchange in vitro. However, some evidence suggests that this is not always the case, as phosphorylation of the GBA motif of GIV promotes its binding to Gαs and inhibits nucleotide exchange. The G-protein specificity of DAPLE and how it might affect nucleotide exchange on G proteins besides Gαi remain to be investigated. Here, we show that DAPLE's GBA motif, in addition to Gαi, binds efficiently to members of the Gs and Gq/11 families (Gαs and Gαq, respectively), but not of the G12/13 family (Gα12) in the absence of post-translational phosphorylation. We pinpointed Met-1669 as the residue in the GBA motif of DAPLE that diverges from that in GIV and enables better binding to Gαs and Gαq. Unlike the nucleotide-exchange acceleration observed for Gαi, DAPLE inhibited nucleotide exchange on Gαs and Gαq. These findings indicate that GBA motifs have versatility in their G-protein–modulating effect, i.e. they can bind to Gα subunits of different classes and either stimulate or inhibit nucleotide exchange depending on the G-protein subtype.This work was supported by National Institutes of Health Grants R01GM108733 and R01GM136132 (to M. G.-M.), American Cancer Society–Funding Hope Postdoctoral Fellowship PF-19-084-01-CDD (to M. M.), a postdoctoral fellowship from the Hartwell Foundation (to V. D.), National Institutes of Health Grant R01GM030355 (to E. M. R.), and National Institutes of Health Grants CA100768 and CA160911 (to P. G.). The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.Peer reviewe

DAPLE protein inhibits nucleotide exchange on Gαs and Gαq via the same motif that activates Gαi

Besides being regulated by G-protein-coupled receptors, the activity of heterotrimeric G proteins is modulated by many cytoplasmic proteins. GIV/Girdin and DAPLE (Dvl-associating protein with a high frequency of leucine) are the best-characterized members of a group of cytoplasmic regulators that contain a Gα-binding and -activating (GBA) motif and whose dysregulation underlies human diseases, including cancer and birth defects. GBA motif-containing proteins were originally reported to modulate G proteins by binding Gα subunits of the Gi/o family (Gαi) over other families (such as Gs, Gq/11, or G12/13), and promoting nucleotide exchange in vitro However, some evidence suggests that this is not always the case, as phosphorylation of the GBA motif of GIV promotes its binding to Gαs and inhibits nucleotide exchange. The G-protein specificity of DAPLE and how it might affect nucleotide exchange on G proteins besides Gαi remain to be investigated. Here, we show that DAPLE's GBA motif, in addition to Gαi, binds efficiently to members of the Gs and Gq/11 families (Gαs and Gαq, respectively), but not of the G12/13 family (Gα12) in the absence of post-translational phosphorylation. We pinpointed Met-1669 as the residue in the GBA motif of DAPLE that diverges from that in GIV and enables better binding to Gαs and Gαq Unlike the nucleotide-exchange acceleration observed for Gαi, DAPLE inhibited nucleotide exchange on Gαs and Gαq These findings indicate that GBA motifs have versatility in their G-protein-modulating effect, i.e. they can bind to Gα subunits of different classes and either stimulate or inhibit nucleotide exchange depending on the G-protein subtype