ACE2 abrogates tumor resistance to VEGFR inhibitors suggesting angiotensin-(1-7) as a therapy for clear cell renal cell carcinoma.

Angiotensin converting enzyme 2 (ACE2) is an enzyme that belongs to the renin-angiotensin system (RAS) and antagonizes the classical angiotensin (Ang) II/angiotensin II receptor type 1 (AT1) receptor pathway. Here, we report that higher ACE2 expression correlates with better overall survival in patients with clear cell renal cell carcinoma (ccRCC). Moreover, ACE2 has inhibitory effects on tumor proliferation in ccRCC in vitro and in preclinical animal models of ccRCC. We further show that Ang-(1-7), a heptapeptide generated by ACE2, is the likely mediator of this effect. Vascular endothelial growth factor receptor-tyrosine kinase inhibitor (VEGFR-TKI) treatment of ccRCC xenografts decreased ACE2 expression, and combination treatment with VEGFR-TKI and Ang-(1-7) generated additive suppression of tumor growth and improved survival outcomes. Last, the addition of Ang-(1-7) to programmed death-ligand 1 (PD-L1) pathway inhibitor and VEGFR-TKI showed further growth suppression in an immunocompetent RCC model. Together, these results suggest that targeting the ACE2/Ang-(1-7) axis is a promising therapeutic strategy against ccRCC.

Neprilysin degrades murine Amyloid-ß (Aß) more efficiently than human Aß: Further implication for species-specific amyloid accumulation.

For over a century, aggregated forms of amyloid-ß protein (Aß) have been viewed as a key hallmark of brains affected by Alzheimer's disease (AD). Today, it remains unknown whether Aß aggregates (oligomers, fibrils or plaques) originate from increased production or decreased catabolism of Aß. Neprilysin (NEP, neutral endopeptidase) is a ubiquitously distributed peptidase, known to degrade Aß, amongst other peptides. In this study, we identified differences in NEP-mediated catabolism of murine and human forms of Aß, using recombinant human NEP, membrane-bound NEP from cells overexpressing the murine peptidase or from human organ preparations with high NEP activity, and purified soluble bovine NEP. NEP degraded murine Aß (mAß) faster than human Aß (hAß). These findings were observed with full-length Aß containing 40 or 42 amino acids (Aß1-40 and Aß1-42) and a truncated form (Aß4-15), which (i) contains one of the main NEP cleavage sites for Aß (between positions 9 and 10), (ii) harbours all three amino acid differences between murine and human Aß sequences, and (iii) is less prone to aggregation and thus might be a simpler model to investigate Aß biochemistry. While it has previously been shown that mAß has a far lower propensity to aggregate than hAß, evidence from this study suggests that a faster NEP-mediated turnover of mAß may provide additional protection against Aß aggregation in murine species.

Decarboxylation of Ang-(1-7) to Ala1-Ang-(1-7) leads to significant changes in pharmacodynamics.

The heptapeptide angiotensin (Ang)-(1-7) is part of the beneficial arm of the renin-angiotensin system. Ang-(1-7) has cardiovascular protective effects, stimulates regeneration, and opposes the often detrimental effects of AngII. We recently identified the G protein-coupled receptors Mas and MrgD as receptors for the heptapeptide. Ala1-Ang-(1-7) (Alamandine), a decarboxylated form of Ang-(1-7), has similar vasorelaxant effects, but has been described as only stimulating MrgD. Therefore, this study aimed to characterise the consequences of the lack of the carboxyl group in amino acid 1 on intracellular signalling and to identify the receptor fingerprint for Ala1-Ang-(1-7). In primary endothelial and mesangial cells, Ala1-Ang-(1-7) elevated cAMP concentration. Dose response curves generated with Ang-(1-7) and Ala1-Ang-(1-7) significantly differed from each other, with a much lower EC50 and a bell-shape curve for Ala1-Ang-(1-7). We provided pharmacological proof that both, Mas and MrgD, are functional receptors for Ala1-Ang-(1-7). Consequently, in primary mesangial cells with genetic deficiency in both receptors, the heptapeptide failed to increase cAMP concentration. As we previously described for Ang-(1-7), the Ala1-Ang-(1-7)-mediated cAMP increase in Mas/MrgD-transfected HEK293 cells and primary cells was blocked by the AT2 receptor blocker, PD123319. The very distinct dose-response curves for both heptapeptides could be explained by in silico modelling, electrostatic potential calculations, and an involvement of Galpha i for higher concentrations of Ala1-Ang-(1-7). Our results identify Ala1-Ang-(1-7) as a peptide with specific pharmacodynamic properties and builds the basis for the design of more potent and efficient Ang-(1-7) analogues for therapeutic intervention in a rapidly growing number of diseases.

Daily activity budgets reveal a quasi-flightless stage during non-breeding in Hawaiian albatrosses.

BACKGROUND: Animals adjust activity budgets as competing demands for limited time and energy shift across life history phases. For far-ranging migrants and especially pelagic seabirds, activity during breeding and migration are generally well studied but the "overwinter" phase of non-breeding has received less attention. Yet this is a critical time for recovery from breeding, plumage replacement and gaining energy stores for return migration and the next breeding attempt. We aimed to identify patterns in daily activity budgets (i.e. time in flight, floating on the water's surface and active foraging) and associated spatial distributions during overwinter for the laysan Phoebastria immutabilis and black-footed P. nigripes albatrosses using state-space models and generalized additive mixed-effects models (GAMMs). We applied these models to time-series of positional and immersion-state data from small light- and conductivity-based data loggers. RESULTS: During overwinter, both species exhibited a consistent 'quasi-flightless' stage beginning c. 30 days after initiating migration and lasting c. 40 days, characterized by frequent long bouts of floating, very little sustained flight, and infrequent active foraging. Minimal daily movements were made within localized areas during this time; individual laysan albatross concentrated into the northwest corner of the Pacific while black-footed albatross spread widely across the North Pacific Ocean basin. Activity gradually shifted toward increased time in flight and active foraging, less time floating, and greater daily travel distances until colony return c. 155 days after initial departure. CONCLUSIONS: Our results demonstrate that these species make parallel adjustments to activity budgets at a daily time-scale within the overwinter phase of non-breeding despite different at-sea distributions and phenologies. The 'quasi-flightless' stage likely reflects compromised flight from active wing moult while the subsequent increase in activity may occur as priorities shift toward mass gain for breeding. The novel application of a GAMM-based approach used in this study offers the possibility of identifying population-level patterns in shifting activity budgets over extended periods while allowing for individual-level variation in the timing of events. The information gained can also help to elucidate the whereabouts of areas important at different times across life history phases for far-ranging migrants.

Sampling design considerations for demographic studies: a case of colonial seabirds.

For the purposes of making many informed conservation decisions, the main goal for data collection is to assess population status and allow prediction of the consequences of candidate management actions. Reducing the bias and variance of estimates of population parameters reduces uncertainty in population status and projections, thereby reducing the overall uncertainty under which a population manager must make a decision. In capture-recapture studies, imperfect detection of individuals, unobservable life-history states, local movement outside study areas, and tag loss can cause bias or precision problems with estimates of population parameters. Furthermore, excessive disturbance to individuals during capture-recapture sampling may be of concern because disturbance may have demographic consequences. We address these problems using as an example a monitoring program for Black-footed Albatross (Phoebastria nigripes) and Laysan Albatross (Phoebastria immutabilis) nesting populations in the northwestern Hawaiian Islands. To mitigate these estimation problems, we describe a synergistic combination of sampling design and modeling approaches. Solutions include multiple capture periods per season and multistate, robust design statistical models, dead recoveries and incidental observations, telemetry and data loggers, buffer areas around study plots to neutralize the effect of local movements outside study plots, and double banding and statistical models that account for band loss. We also present a variation on the robust capture-recapture design and a corresponding statistical model that minimizes disturbance to individuals. For the albatross case study, this less invasive robust design was more time efficient and, when used in combination with a traditional robust design, reduced the standard error of detection probability by 14% with only two hours of additional effort in the field. These field techniques and associated modeling approaches are applicable to studies of most taxa being marked and in some cases have individually been applied to studies of birds, fish, herpetofauna, and mammals.