OBJECTIVETitin is recently known as the largest protein which exists in the striated muscle sarcomere and is dynamic both in biomechanics properties and biochemical functions. Four possible disease-associated mutations located in three exons (3, 14, 49) of titin gene (TTN) have been identified in Japanese DCM patients in 2002. We observed the possible association of TTN mutation in Chinese patients with DCM.

METHODSThree exons of TTN (3, 14, 49) were screened in 117 DCM patients and 120 controls by polymerase chain reaction-single strand conformation polymorphisms (PCR-SSCP) and DNA sequence. SSCP was carried out following a protocol optimized for each PCR fragment after amplification. Abnormal SSCP results were subsequently confirmed by DNA sequencing.

RESULTSThe mutations reported in Japanese DCM patients were not identified in this patient cohort. A novel mutation [the G13053A (TTN cDNA sequence, X90568) change resulted in amino acid change at position 4351 (Gly4351Asp)] was found in two young DCM patients from a DCM family (1.7%). There was no similar mutation in controls.

CONCLUSIONThis novel Gly4351Asp mutation in TTN might be associated with DCM.

Aged ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Cardiomyopathy, Dilated ; genetics ; Case-Control Studies ; Connectin ; DNA Mutational Analysis ; Female ; Genotype ; Humans ; Male ; Middle Aged ; Muscle Proteins ; genetics ; Mutation ; Polymorphism, Single-Stranded Conformational ; Protein Kinases ; genetics

[Objective]To investigate the effect of human umbilical cord mesenchymal stem cells on infected state of human alve?olar type Ⅱ epithelial cells.[Methods]Human alveolar type Ⅱ epithelial cells A549(1×105/mL)2 mL and PA(3×104 CFU/mL)2 mL has grown after 6 hours,add hUCMSC(1 × 106/mL)2 mL as the experimental group,add equal amounts of phosphate buffer (PBS)for infection,A549 and PBS and the medium has grown as the control group. A549 cells morphological changes between the compared groups(Transmission electron microscope,TEM),A549 cell viability(new CCK-8 cell proliferation assay Kit),A549 cells apoptosis(Annexin V-FITC/PI double staining flow cytometry)and the expression of A549 pulmonary surfactant A(SP-A) (Western blot).[Results]Transmission electron microscope cell morphology observation displayed ,infection group A549 cell dam?aged obviously,cell quality appeared empty bubble degeneration,chromatin height agglutination,visible apoptosis bodies;experi?ment group cell package film structure full,nuclear film full,nucleolus obviously,nuclear chromatin electronic density low,chroma? tin uniform,no apoptotic bodies;control group A549 cell structure full,membrane surface micro-fluff rich,nuclear film full,nucle?ar week clearance structure normal,chromatin uniform;infection group and control group compared,Infection group A549 cell sur?vival significantly reduced[(70.35±2.89)% and(97.37±2.07)%,n=3,P<0.01],apoptosis rate significantly increased[(8.63%± 0.16)%and(2.55±0.11)%,n=3,P<0.01],In the infected group,PA could damage A549 cells and decrease the amount of SP-A ex?pression(n=5,P<0.05). In the experiment group,the protective effect of hUCMSC on the A549 cells after infection may increase the expression of SP-A(n=5,P<0.05);[Conclusions]HUCMSC inhibits the infection of A549 cells apoptosis and protection of A549 cells secrete SP-A.