Interactions between oxygen homeostasis, food availability, and hydrogen sulfide signaling

Abstract

The ability to sense and respond to stressful conditions is essential to maintain organismal homeostasis. It has long been recognized that stress response factors that improve survival in changing conditions can also influence longevity. In this review, we discuss different strategies used by animals in response to decreased O2 (hypoxia) to maintain O2 homeostasis, and consider interactions between hypoxia responses, nutritional status, and H2S signaling. O2 is an essential environmental nutrient for almost all metazoans as it plays a fundamental role in development and cellular metabolism. However, the physiological response(s) to hypoxia depend greatly on the amount of O2 available. Animals must sense declining O2 availability to coordinate fundamental metabolic and signaling pathways. It is not surprising that factors involved in the response to hypoxia are also involved in responding to other key environmental signals, particularly food availability. Recent studies in mammals have also shown that the small gaseous signaling molecule hydrogen sulfide (H2S) protects against cellular damage and death in hypoxia. These results suggest that H2S signaling also integrates with hypoxia response(s). Many of the signaling pathways that mediate the effects of hypoxia, food deprivation, and H2S signaling have also been implicated in the control of lifespan. Understanding how these pathways are coordinated therefore has the potential to reveal new cellular and organismal homeostatic mechanisms that contribute to longevity assurance in animals.

Redox modification of proteins as essential mediators of CNS autophagy and mitophagy

“…Although hypoxic conditions disrupt neuronal metabolic and redox tone, not all neurons are equally vulnerable to hypoxia; for instance, CA1 hippocampal neurons are some of the most sensitive [91]. At sea level, atmospheric oxygen is approximately 20%, but oxygen present in vivo in tissue is lower than ambient oxygen [92]. Furthermore, levels of oxygen vary between tissue in vivo (20-40 mmHg) [93], cells in vivo (1-10 mmHg) and cells grown in culture (150 mmHg) [94], providing yet another caveat to studying the consequences of hypoxic stress.…”

HIF-1-mediated expression of Foxo1 serves an important role in the proliferation and apoptosis of osteoblasts derived from children's iliac cancellous bone

“…The maintenance of the normal functional state of the body is dependent on an appropriate supply of oxygen. In addition, maintaining homeostasis in regard to oxygen levels is a prerequisite for cell life activity (2), and tissue oxygen concentrations must be precisely controlled to fluctuate only within a very small range (2,3). Due to a reduction in blood supply following bone or soft tissue injury, the microenvironment surrounding lesions enters a hypoxia state (4).…”

Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification

“…The role of food availability in the capacity of bivalves to cope with stressful conditions, such as extreme temperature (i.e., Hoogenboom et al ., ), low salinity (i.e., Fernández‐Reiriz et al ., ), or hypoxia (i.e., Iranon & Miller, ), has been amply documented. However, the role of food supply in possibly mitigating the negative effects of OA on marine calcifiers has received limited attention to‐date.…”