Obstetric and perinatal outcomes for women with pre-existing diabetes in rural compared to metropolitan settings in Victoria, Australia.

BACKGROUND: Pre-existing diabetes in pregnancy is associated with an increased risk of complications. Likewise, living in rural, regional and remote Victoria, Australia, is also associated with poorer health outcomes. There is a gap in the literature with regard to whether Victorian women with pre-existing diabetes experience a greater risk of adverse pregnancy outcomes compared to their metropolitan counterparts. AIM: Our objective is to compare obstetric and perinatal outcomes for women with pre-existing diabetes delivering in rural vs metropolitan hospitals in Victoria, Australia. MATERIALS AND METHODS: Retrospective population-based study using routinely collected state-based data of singleton births to women with type 1 and type 2 diabetes who delivered in metropolitan (n = 3233) and rural hospitals (n = 693) in Victoria, Australia, between 2006-2015. Pearson's χ2 test, Fisher's exact test and MannWhitney U-test were used to compare obstetric and perinatal outcomes between metropolitan and rural locations. RESULTS: Delivery in a rural hospital was associated with higher rates of stillbirth (2.3% vs 1.1%, P = 0.027), macrosomia (25.9% vs 16.9%, P < 0.001), shoulder dystocia (8.4% vs 3.5%, P < 0.001) and admission to the neonatal intensive care unit/special care nursery (73.2% vs 59.3%, P < 0.001). Smoking (18.0% vs 8.9%, P < 0.001), overweight/obesity (P = 0.047) and socioeconomic disadvantage (P < 0.001) were more common in rural women. CONCLUSIONS: Women with pre-existing diabetes who deliver in rural hospitals experience a greater risk of adverse perinatal outcomes and present with increased maternal risk factors. These results suggest a need to improve care for women with pre-existing diabetes in rural Victoria.

Disruption of amyloid precursor protein ubiquitination selectively increases amyloid ß (Aß) 40 levels via presenilin 2-mediated cleavage.

Amyloid plaques, a neuropathological hallmark of Alzheimer's disease, are largely composed of amyloid ß (Aß) peptide, derived from cleavage of amyloid precursor protein (APP) by ß- and γ-secretases. The endosome is increasingly recognized as an important crossroad for APP and these secretases, with major implications for APP processing and amyloidogenesis. Among various post-translational modifications affecting APP accumulation, ubiquitination of cytodomain lysines may represent a key signal controlling APP endosomal sorting. Here, we show that substitution of APP C-terminal lysines with arginine disrupts APP ubiquitination and that an increase in the number of substituted lysines tends to increase APP metabolism. An APP mutant lacking all C-terminal lysines underwent the most pronounced increase in processing, leading to accumulation of both secreted and intracellular Aß40. Artificial APP ubiquitination with rapalog-mediated proximity inducers reduced Aß40 generation. A lack of APP C-terminal lysines caused APP redistribution from endosomal intraluminal vesicles (ILVs) to the endosomal limiting membrane, with a subsequent decrease in APP C-terminal fragment (CTF) content in secreted exosomes, but had minimal effects on APP lysosomal degradation. Both the increases in secreted and intracellular Aß40 were abolished by depletion of presenilin 2 (PSEN2), recently shown to be enriched on the endosomal limiting membrane compared with PSEN1. Our findings demonstrate that ubiquitin can act as a signal at five cytodomain-located lysines for endosomal sorting of APP. They further suggest that disruption of APP endosomal sorting reduces its sequestration in ILVs and results in PSEN2-mediated processing of a larger pool of APP-CTF on the endosomal membrane.

Phosphatidylinositol-3-phosphate regulates sorting and processing of amyloid precursor protein through the endosomal system.

Defects in endosomal sorting have been implicated in Alzheimer's disease. Endosomal traffic is largely controlled by phosphatidylinositol-3-phosphate, a phosphoinositide synthesized primarily by lipid kinase Vps34. Here we show that phosphatidylinositol-3-phosphate is selectively deficient in brain tissue from humans with Alzheimer's disease and Alzheimer's disease mouse models. Silencing Vps34 causes an enlargement of neuronal endosomes, enhances the amyloidogenic processing of amyloid precursor protein in these organelles and reduces amyloid precursor protein sorting to intraluminal vesicles. This trafficking phenotype is recapitulated by silencing components of the ESCRT (Endosomal Sorting Complex Required for Transport) pathway, including the phosphatidylinositol-3-phosphate effector Hrs and Tsg101. Amyloid precursor protein is ubiquitinated, and interfering with this process by targeted mutagenesis alters sorting of amyloid precursor protein to the intraluminal vesicles of endosomes and enhances amyloid-beta peptide generation. In addition to establishing phosphatidylinositol-3-phosphate deficiency as a contributing factor in Alzheimer's disease, these results clarify the mechanisms of amyloid precursor protein trafficking through the endosomal system in normal and pathological states.