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Type 2 inositol 1,4,5-trisphosphate receptor (IP3R2) regulates the intracellular Ca2+ release from endoplasmic reticulum in human embryonic stem cells (hESCs), cardiovascular progenitor cells (CVPCs), and mammalian cardiomyocytes. However, the role of IP3R2 in human cardiac development is unknown and its function in mammalian cardiomyocytes is controversial. hESC-derived cardiomyocytes have unique merits in disease modeling, cell therapy, and drug screening. Therefore, understanding the role of IP3R2 in the generation and function of human cardiomyocytes would be valuable for the application of hESC-derived cardiomyocytes. In the current study, we investigated the role of IP3R2 in the differentiation of hESCs to cardiomyocytes and in the hESC-derived cardiomyocytes. By using IP3R2 knockout (IP3R2KO) hESCs, we showed that IP3R2KO did not affect the self-renewal of hESCs as well as the differentiation ability of hESCs into CVPCs and cardiomyocytes. Furthermore, we demonstrated the ventricular-like myocyte characteristics of hESC-derived cardiomyocytes. Under the α1-adrenergic stimulation by phenylephrine (10 μmol/L), the amplitude and maximum rate of depolarization of action potential (AP) were slightly affected in the IP3R2KO hESC-derived cardiomyocytes at differentiation day 90, whereas the other parameters of APs and the Ca2+ transients did not show significant changes compared with these in the wide-type ones. These results demonstrate that IP3R2 has minimal contribution to the differentiation and function of human cardiomyocytes derived from hESCs, thus provide the new knowledge to the function of IP3R2 in the generation of human cardiac lineage cells and in the early cardiomyocytes.

Type 2 inositol 1,4,5-trisphosphate receptor (IP 3 R2) regulates the intracellular Ca 2+ release from endoplasmic reticulum in human embryonic stem cells (hESCs), cardiovascular progenitor cells (CVPCs), and mammalian cardiomyocytes. However, the role of IP 3 R2 in human cardiac development is unknown and its function in mammalian cardiomyocytes is controversial. hESC-derived cardiomyocytes have unique merits in disease modeling, cell therapy, and drug screening. Therefore, understanding the role of IP 3 R2 in the generation and function of human cardiomyocytes would be valuable for the application of hESC-derived cardiomyocytes. In the current study, we investigated the role of IP 3 R2 in the differentiation of hESCs to cardiomyocytes and in the hESC-derived cardiomyocytes. By using IP 3 R2 knockout (IP 3 R2KO) hESCs, we showed that IP 3 R2KO did not affect the self-renewal of hESCs as well as the differentiation ability of hESCs into CVPCs and cardiomyocytes. Furthermore, we demonstrated the ventricular-like myocyte characteristics of hESC-derived cardiomyocytes. Under the α 1 -adrenergic stimulation by phenylephrine (10 μmol/L), the amplitude and maximum rate of depolarization of action potential (AP) were slightly affected in the IP 3 R2KO hESC-derived cardiomyocytes at differentiation day 90, whereas the other parameters of APs and the Ca 2+ transients did not show significant changes compared with these in the wide-type ones. These results demonstrate that IP 3 R2 has minimal contribution to the differentiation and function of human cardiomyocytes derived from hESCs, thus provide the new knowledge to the function of IP 3 R2 in the generation of human cardiac lineage cells and in the early cardiomyocytes.

Aim: To investigate the correlation between calcium treatment in postmenopausal women and estrogen receptor-alpha (ER-alpha) Xba I and Pvu II genotype and vitamin D receptor (VDR) Apa I genotype., Methods: One hundred fifteen postmenopausal Chinese women of Han population were enrolled and treated with calcichew-D3 (1000 mg calcium and 400 U vitamin D3) daily for 1 year. At entry and after 1 year treatment, the bone mineral density (BMD), serum and urinary bone turnover biochemical markers were evaluated. ER-alpha and VDR genotype were analyzed using PCR-restriction fragment length polymorphism., Results: After 1 year of calcium supplementation, a significant increase of BMD and a marked reduction in serum ALP and PTH levels, and a significant increase of serum 25-(OH) vitamin D level were observed (P<0.01 or P<0.05). At entry and after 1 year of treatment, no significant association was found between Xba I, Pvu II, and Apa I genotypes and BMD in L1-4, Neck, and Troch, and all bone turnover marker levels. However, the percentage of change (median, QR) in Neck BMD was significantly different in homozygous XX [-4.14 (from -6.54 to -1.34)] in comparison with Xx [1.72 (from -1.12 to 3.20)] (P<0.001) or xx [1.22 (from -1.74 to 3.06)] Xba I ER-alpha genotype (P=0.001)., Conclusion: Women with ER-alpha Xba I genotype XX may have a higher risk of relatively fast bone mass loss in femoral neck after menopause and that they may have a poor responsiveness to calcium supplementation. The changes in BMD are not associated with ER-alpha Pvu II genotype and VDR Apa I genotype after 1 year of calcium supplementation.

Aim: To investigate if vitamin D receptor (VDR) gene Apa I polymorphism and estrogen receptor-alpha (ER-alpha) gene Pvu II, Xba I polymorphisms are related to bone mineral density (BMD), bone mineral content (BMC) and bone size in premenopausal Chinese women., Methods: The VDR Apa I genotype and ER-alpha Pvu II, Xba I genotype were determined by PCR-restriction fragment length polymorphism (RFLP) in 493 unrelated healthy women aged 20-40 years of Han nationality in Shanghai city. BMD (g/cm(2)), BMC (g), and bone areal size (BAS, cm(2) ) at lumbar spine 1-4 (L(1-4)) and proximal femur (femoral neck, trochanter and Ward's triangle) were measured by duel-energy X-ray absorptionmetry., Results: All allele frequencies did not deviate from Hardy-Weinberg equilibrium. After phenotypes were adjusted for age, height, and weight, a significant association was found between VDR Apa I genotype and BMC variation at L(1-4) and Ward's triangle (P<0.05), but not in BMD or BAS at lumbar spine and proximal femur. ER-a Pvu II, Xba I genotype was not related to BMC, BMD, and BAS at all sites., Conclusion: The study suggested that Apa I polymorphism in VDR gene may influence on attainment and maintenance of peak bone mass in premenopausal Chinese women.