The major urinary protein system in the rat

Area of Science:

• Biochemistry
• Genomics
• Animal Behavior

Background:

• Rats and mice possess gene clusters encoding small, eight-stranded beta-barrel lipocalins, known as major urinary proteins (MUPs).
• These MUPs are synthesized in secretory tissues and can be excreted in urine via hepatic pathways.
• While mouse MUPs are well-studied, particularly for their role in chemical communication, rat MUP literature is fragmented.

Purpose of the Study:

• To review and synthesize the existing literature on major urinary proteins (MUPs) in the Norway rat (Rattus norvegicus).
• To consolidate fragmented knowledge regarding rat MUPs, analogous to the well-understood mouse MUP system.
• To provide a comprehensive overview of rat MUPs, including their biosynthesis, tissue expression, and potential functions.

Main Methods:

• Literature review and synthesis of published studies on rat MUPs.
• Comparative analysis of rat MUPs with their well-characterized mouse orthologues.
• Compilation of data on MUP gene clusters, protein structure, expression patterns, and known or proposed functions in Rattus norvegicus.

Main Results:

• Rats, like mice, have a MUP gene cluster encoding multiple small lipocalins.
• Rat MUPs are expressed in various secretory tissues and some enter the urine through hepatic biosynthesis.
• Evidence suggests potential roles for rat MUPs in intraspecific chemical communication, though less established than in mice.

Conclusions:

• The Norway rat possesses a complex MUP system with similarities to mice, including hepatic biosynthesis and urinary excretion.
• Further research is needed to fully elucidate the functions of rat MUPs, particularly in chemical communication.
• Consolidating current knowledge is crucial for advancing the understanding of rat MUPs and their biological significance.