Acute exercise increases syndecan-1 and -4 serum concentrations.

Area of Science:

• Biochemistry
• Exercise Physiology
• Metabolic Health

Background:

• Syndecans are cell surface proteoglycans involved in cellular processes.
• The impact of exercise on syndecan levels and their link to insulin sensitivity remains unclear.
• Dysglycemia is associated with metabolic dysfunction and altered cellular signaling.

Purpose of the Study:

• To investigate the effects of acute and 12-week exercise interventions on serum syndecan-1 and -4 levels.
• To analyze gene expression related to syndecan metabolism in skeletal muscle and adipose tissue.
• To determine the relationship between syndecan levels, gene expression, and insulin sensitivity in men with and without dysglycemia.

Main Methods:

• Participants: Sedentary men with (n=13) or without (n=13) dysglycemia.
• Intervention: Two 45-minute acute exercise bouts interspersed with a 12-week exercise program.
• Measurements: Euglycemic-hyperinsulinemic clamp for insulin sensitivity, serum syndecan quantification, and mRNA sequencing of muscle and adipose tissue biopsies.

Main Results:

• Acute exercise increased serum syndecan-1 and -4 levels, suggesting glycocalyx shedding.
• Baseline serum syndecan-4 was higher in dysglycemic men and correlated with insulin sensitivity.
• Adipose tissue showed upregulated mRNA for syndecan structure/shedding in dysglycemia; muscle mRNA responded to long-term exercise.

Conclusions:

• Acute exercise transiently affects serum syndecan levels, possibly impacting the glycocalyx.
• Syndecan-4 may play a role in metabolic regulation and insulin sensitivity, particularly in dysglycemia.
• Exercise modulates syndecan-related gene expression in metabolic tissues, with differential responses between muscle and adipose tissue.