GDF11 and aging biology - controversies resolved and pending

Since the exogenous administration of GDF11, a TGF-ß superfamily member, was reported to have beneficial effects in some models of human disease, there have been many research studies in GDF11 biology. However, many studies have now confirmed that exogenous administration of GDF11 can improve physiology in disease models, including cardiac fibrosis, experimental stroke, and disordered metabolism. GDF11 is similar to GDF8 (also called Myostatin), differing only by 11 amino acids in their mature signaling domains. These two proteins are now known to be biochemically different both in vitro and in vivo. GDF11 is much more potent than GDF8 and induces more strongly SMAD2 phosphorylation in the myocardium compared to GDF8. GDF8 and GDF11 prodomain are only 52% identical and are cleaved by different Tolloid proteases to liberate the mature signaling domain from inhibition of the prodomain. Here, we review the state of GDF11 biology, highlighting both resolved and remaining controversies.

Molecular Mechanisms of Central Nervous System Axonal Regeneration and Remyelination: A Review

Central nervous system (CNS) injury, including stroke, spinal cord injury, and traumatic brain injury, causes severe neurological symptoms such as sensory and motor deficits. Currently, there is no effective therapeutic method to restore neurological function because the adult CNS has limited capacity to regenerate after injury. Many efforts have been made to understand the molecular and cellular mechanisms underlying CNS regeneration and to establish novel therapeutic methods based on these mechanisms, with a variety of strategies including cell transplantation, modulation of cell intrinsic molecular mechanisms, and therapeutic targeting of the pathological nature of the extracellular environment in CNS injury. In this review, we will focus on the mechanisms that regulate CNS regeneration, highlighting the history, recent efforts, and questions left unanswered in this field.