The Expression And Regulation Mechanism Of Adipocyte Fatty Acid-Binding Protein (FABP4) In Cardiomyocytes

Objective:Fatty acid-binding proteins(FABPs)are a group of molecules that coordinate intracellular lipid responses,mainly involved in the binding and transport of fatty acids,and are closely related to metabolism and inflammation.At present,the FABPs family has identified 9 members,among which fatty acid-binding protein 3(FABP3),also known as cardiac fatty acid binding protein,is expressed in cardiomyocytes in large quantities and can be used as a biomarker for acute myocardial infarction in clinic.Fatty acidbinding protein 4(FABP4),also known as adipocyte fatty acid binding protein,is structurally very similar to FABP3 and is mainly expressed in adipose tissue and macrophages.However,its expression and regulation mechanism in cardiomyocytes are not yet clear.In recent years,the function of FABP4 in the cardiovascular system has attracted more and more attention.In particular,the increase of FABP4 in serum can inhibit the contraction of cardiomyocytes,cause ventricular contraction and diastolic function,and then affect ventricular remodeling.It is closely related to the occurrence and progression of heart diseases such as heart failure and hypertrophic cardiomyopathy.Therefore,the main purpose of this project is to clarify the expression of FABP4 in cardiomyocytes and its potential regulatory mechanisms by molecular biology methods,and provide a new strategy for the treatment of clinical heart disease.Methods:1.Experimental animalHealthy C57BL/6 mice 12-14 weeks of age feeded in an SPF grade environment were used in this study.2.Western blot was used to detect the protein expression of FABP4 in mouse heart tissue.3.Western blot was used to detect the protein expression of FABP3 and FABP4 in mouse ventricular myocytes.4.qRT-PCR was used to detect the mRNA expression of FABP3 and FABP4 in mouse ventricular myocytes.5.Co-immunoprecipitation to study the interaction of FABP4 with DRD1 and DRD2.6.Statistical processing and related analysis:The data was represented by MEAN ± SE.SPSS 13.0software was used for statistical analysis.The test was significant at P<0.05.Results: 1.Western blot results showed that FABP4 protein expression can be detected in cardiac tissue.2.Western blot results showed that FABP3 and FABP4 protein expression can be detected in cardiomyocytes.3.qRT-PCR results showed that there were FABP3 and FABP4 mRNA in cardiomyocytes,but the amount of FABP4 mRNA is not proportional to FABP4 protein compared with FABP3.Our data indicated that FABP4 can be secreted from the extracellular environment into cardiomyocytes.4.Co-immunoprecipitation results indicate that FABP4 interacts with DRD1 to regulate the extracellular FABP4 into cardiomyocytes.Conclusions:1.Studies have shown that FABP4 is present in cardiomyocytes.In addition,although most of the FABP4 may be derived from the extracellular environment,cardiomyocytes are capable of producing sufficient amounts of FABP4.2.In addition to binding to and activating DRD1,extracellular FABP4 may also enter the interior of cardiomyocytes via DRD1-mediated endocytosis on the cardiomyocyte membrane.It plays a role in inhibiting myocardial cell contraction and affecting ventricular remodeling,plays an important role in different heart disease states.