FGD5 Regulates VEGF Receptor-2 Coupling to PI3 Kinase and Receptor Recycling
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
Authors: Farhan, Maikel A.; Azad, Abul K.; Touret, Nicolas; Murray, Allan G.
Abstract
Objective-VEGF (vascular endothelial growth factor-A) signaling to the endothelial cell (EC) through VEGFR2 (VEGF receptor-2) is the principal cue driving new blood vessel formation. FGD5 (faciogenital dysplasia-5)-a Rho-family guanine nucleotide exchange factor-is selectively expressed in EC. Deficiency of FGD5 is embryonically lethal in mice and perturbs angiogenesis and VEGF signal transduction. However, the mechanism of FGD5 regulation of VEGF signaling is poorly understood. Approach and Results-Angiogenic sprouting and EC cytoskeletal remodeling were evaluated in a 3-dimensional in vitro model. We examined the subcellular localization of FGD5 and VEGFR2 in EC by immunofluorescent staining and studied the association by immunoprecipitation. FGD5 deficiency reduced the number of angiogenic sprouts and tip cell filopodia by approximate to 80% and approximate to 70%, respectively. These defects were accompanied by downregulation of the expression of tip cell-specific markers. FGD5 inactivation led to a decrease in EC migration and early protrusion (lamellipodia) formation. In resting and VEGF-stimulated EC, FGD5 forms a complex with VEGFR2 and was enriched at the leading edge of the cell and among endosomes. FGD5 loss reduced mTORC2 (mammalian target of rapamycin complex-2)/Aktdependent cortactin activation downstream of VEGFR2 but did not alter VEGFR2 plasma membrane expression, Y1175 phosphorylation, or endocytosis. However, FGD5 loss decreased endosomal VEGFR2 coupling to phosphoinositide-3 kinase and diverted VEGFR2 to lysosomal degradation. Conclusions-FGD5 regulates VEGFR2 retention in recycling endosomes and coupling to PI3 (phosphoinositide-3) kinase/mTORC2-dependent cytoskeletal remodeling. Visual Overview-An online visual overview is available for this article.
Community perceptions and personal accounts of HIV discordance in rural western Kenya
AJAR-AFRICAN JOURNAL OF AIDS RESEARCH
Authors: Ondenge, Ken; Odero, Isdorah; Awuonda, Eucabeth; Omoro, Tereza; Kibogo, Michael; Otieno, George; Ongwena, Pauline; Gust, Deborah A.
Abstract
Among HIV-discordant couples, the literature is sparse regarding issues related to stigma, relationships and coping. Objectives were to explore: 1) perceptions about discordant HIV status; 2) understanding of HIV discordancy: 3) effects of discordancy on couples; and 4) adaptation and coping strategies for discordant HIV status. A survey was administered to 202 members of heterosexual discordant couples in rural western Kenya. In addition, to understand the community perspective, in-depth interviews (IDI) (n = 26) and focus group discussions (FGD) (n = 10) were conducted with community opinion leaders, healthcare workers and members of discordant couples. More than 70% of men (73.4%) and women (80.4%) surveyed agreed that their relationship changed for the worse when they disclosed their HIV status to their partner. Participants of IDIs and FGD5 provided several explanations for discordancy including the perception that discordancy is a lie, the negative partner has "thick blood", HIV infection is a punishment for sexual promiscuity or cultural disobedience, and that HIV is a punishment from God. Members of discordant couples reported experiencing tension and fear, stigma and rejection, and changes in partner support. Adaptation and coping strategies included counselling, sero-sorting and pursuing concordancy with the uninfected partner. HIV discordancy in a relationship can potentially cause long-term negative emotional and physical consequences. There is an acute need to develop and disseminate locally sensitive HIV-discordant couple counselling messages, and to provide couple-centred HIV care and treatment. Communication can help couples rebuild and rebalance their relationship and adjust to a new normal.