Identification of truncated form of mouse HAX-1s gene (HAX-1xs) and characterization of its expression in small intestine and thymus of mice after burn injury.

Burn injury often leads to distant organ injury such as acute respiratory distress syndrome. We hypothesize that the pathophysiologic changes in distant organs result from orchestrated regulation of multiple genes in response to bum injury. Differential display was performed to identify genes regulated in distant organs in response to burn injury. Initial characterization of differentially amplified products demonstrated that HAX-1s mRNA was regulated in several distant organs after 18% total body surface area (TBSA) full-thickness flame burn injury in mice. Further characterization of HAX-1s mRNA revealed a novel transcript variant, which is rapidly and transiently induced in multiple tissues of mice within 6 h after burn injury. This novel HAX-1s transcript variant, called HAX-1xs, has an internal deletion of 252 nucleotides and single point mutation, resulting in reading frame intact. Western blot and immunohistochemical analyses of multiple tissues of mice using rabbit antibody raised against a 15-mer synthetic peptide clearly revealed the presence of HAX-1xs protein in the duodenum, and suggested that expression of HAX-1xs and/or HAX-1s was tissue- and cell type-specific. The expression of HAX-1xs and/or HAX-1s was distinctively regulated in Paneth cells of the duodenum and macrophages of the thymus after burn injury. These findings suggest that HAX-1xs has a different biological activity from HAX-1s and participates in a cascade of immediate-early cellular events in response to burn injury.