Expression patterns of FHL/SLIM family members suggest important functional roles in skeletal muscle and cardiovascular system

LIM domain containing proteins play critical roles in animal development an d cellular differentiation. Here, we describe the cloning and expression pa tterns of three members of the four and a half LIM domain-only protein fami ly, FHL1, 2, and 3, from mouse. A comparison of embryonic expression patter ns of these three highly-related genes indicates that they are expressed in an overlapping pattern in the developing cardiovascular system, and skelet al muscle. In adult tissues, the three genes are expressed in a predominant and overlapping manner in cardiac and skeletal muscle. Of the three genes, FHL2 appears to have the most restricted expression pattern during develop ment, in heart, blood vessels, and skeletal muscle. Expression in heart is highest in cardiac septa and in the region adjacent to the atrio-ventricula r ring, suggesting a potential role in septation or conduction system devel opment. In the heart, FHL1 expression was observed strongly in developing o utflow tract, and to a lesser extent in myocardium. FHL3 displays low and u biquitous expression during mouse development. Cardiac ventricular expressi on of FHL1, but not FHL2 or FHL3, was upregulated in two mouse models of ca rdiac hypertrophic and dilated cardiomyopathy. Taken together, these data i ndicate the potential importance of this FHL family in the development and maintenance of the cardiovascular system and striated muscle, and suggest t hat FHL1 may play a role in the development of heart disease. (C) 2000 Else vier Science Ireland Ltd. All rights reserved.