Resistinlike

Resistinlike refers to a family of small secreted, cysteine-rich proteins known collectively as resistin-like molecules (RELMs). In mammals, RELMs are encoded by the Retnla, Retnlb, and Retnlc genes in mice—designated RELM-alpha, RELM-beta, and RELM-gamma—and represent resistin-like paralogs with tissue-specific expression. In humans, the closest characterized homolog is resistin (RETN), but the RELM family in humans is less clearly defined, and functional roles can differ from those in mice.

Expression and distribution vary among RELM members. RELM-alpha is expressed in adipose tissue and lung; RELM-beta is predominantly produced by intestinal goblet cells and the colon; RELM-gamma has more restricted expression in immune-related tissues. RELMs are secreted signaling proteins that participate in metabolic regulation and immune responses, and their expression can change in obesity, metabolic syndrome, inflammatory bowel disease, and other inflammatory conditions in animal models.

Functions and mechanisms attributed to RELMs include modulation of energy metabolism and insulin sensitivity, as well as participation in inflammatory and immune processes. In rodents, RELMs have been linked to adipose tissue–driven metabolic effects and to Th2-type inflammatory responses. Human resistin has associations with insulin resistance and inflammatory states, but the precise roles and signaling pathways differ across species, and receptor identities remain to be clearly defined.

Clinical relevance and research direction emphasize RELMs as potential biomarkers or therapeutic targets for metabolic and inflammatory diseases. However, there are no approved RELM-targeted therapies, and further research is needed to clarify species-specific functions, receptor interactions, and translational potential.