Previous studies showed that conotruncal heart malformations can arise with the increase or decrease in α1 connexin function in neural crest cells. To elucidate the possible basis for the quantitative requirement for α1 connexin gap junctions in cardiac development, a neural crest outgrowth culture system was used to examine migration of neural crest cells derived from CMV43 transgenic embryos overexpressing α1 connexins, and from α1 connexin knockout (KO) mice and FC transgenic mice expressing a dominant-negative α1 connexin fusion protein. These studies showed that the migration rate of cardiac neural crest was increased in the CMV43 embryos, but decreased in the FC transgenic and α1 connexin KO embryos. Migration changes occurred in step with connexin gene or transgene dosage in the homozygous vs. hemizygous α1 connexin KO and CMV43 embryos, respectively. Dye coupling analysis in neural crest cells in the outgrowth cultures and also in the living embryos showed an elevation of gap junction communication in the CMV43 transgenic mice, while a reduction was observed in the FC transgenic and α1 connexin KO mice. Further analysis using oleamide to downregulate gap junction communication in nontransgenic outgrowth cultures showed that this independent method of reducing gap junction communication in cardiac crest cells also resulted in a reduction in the rate of crest migration. To determine the possible relevance of these findings to neural crest migration in vivo, a lacZ transgene was used to visualize the distribution of cardiac neural crest cells in the outflow tract. These studies showed more lacZ-positive cells in the outflow septum in the CMV43 transgenic mice, while a reduction was observed in the α1 connexin KO mice. Surprisingly, this was accompanied by cell proliferation changes, not in the cardiac neural crest cells, but in the myocardium— an elevation in the CMV43 mice vs. a reduction in the α1 connexin KO mice. The latter observation suggests that cardiac neural crest cells may have a role in modulating growth and development of non–neural crest– derived tissues. Overall, these findings suggest that gap junction communication mediated by α1 connexins plays an important role in cardiac neural crest migration. Furthermore, they indicate that cardiac neural crest perturbation is the likely underlying cause for heart defects in mice with the gain or loss of α1 connexin function.

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Connexin 43 (Cx43α1) gap junction has been shown to have an essential role in mediating functional coupling of neural crest cells and in modulating neural crest cell migration. Here, we showed that N-cadherin and wnt1 are required for efficient dye coupling but not for the expression of Cx43α1 gap junctions in neural crest cells. Cell motility was found to be altered in the N-cadherin–deficient neural crest cells, but the alterations were different from that elicited by Cx43α1 deficiency. In contrast, wnt1-deficient neural crest cells showed no discernible change in cell motility. These observations suggest that dye coupling may not be a good measure of gap junction communication relevant to motility. Alternatively, Cx43α1 may serve a novel function in motility. We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43α1. Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43α1 deficiency. Based on these findings, we propose a model in which Cx43α1 and N-cadherin may modulate neural crest cell motility by engaging in a dynamic cross-talk with the cell's locomotory apparatus through p120ctn signaling.

To investigate the association of folate and vitamin B 12 in early pregnancy with gestational diabetes mellitus (GDM) risk. RESEARCH DESIGN AND METHODSThe data of this study were from a subcohort within the Shanghai Preconception Cohort Study. We included pregnancies with red blood cell (RBC) folate and vitamin B 12 measurements at recruitment (between 9 and 13 gestational weeks) and those with three samples available for glucose measurements under an oral glucose tolerance test. GDM was diagnosed between 24 and 28 weeks' gestation. Odds ratio (OR) and 95% CI of having GDM was used to quantify the association. RESULTSA total of 1,058 pregnant women were included, and GDM occurred in 180 (17.01%). RBC folate and vitamin B 12 were significantly higher in pregnancies with GDM than those without GDM (P values were 0.045 and 0.002, respectively) and positively correlated with 1-h and 2-h serum glucose. Daily folic acid supplementation in early pregnancy increases the risk of GDM; OR (95% CI) was 1.73 (1.19-2.53) (P 5 0.004). Compared with RBC folate <400 ng/mL, pregnancies with RBC folate ‡600 ng/mL were associated with ∼1.60-fold higher odds of GDM; the adjusted OR (95% CI) was 1.58 (1.03-2.41) (P 5 0.033). A significant trend of risk effect on GDM risk across categories of RBC folate was observed (P trend 5 0.021). Vitamin B 12 was significantly associated with GDM risk (OR 1.14 per 100 pg/mL; P 5 0.002). No significant association of serum folate and percentile ratio of RBC folate/vitamin B 12 with GDM was observed. CONCLUSIONSHigher maternal RBC folate and vitamin B 12 levels in early pregnancy are significantly associated with GDM risk, while the balance of folate/vitamin B 12 is not significantly associated with GDM.As one of the most common pregnancy complications, gestational diabetes mellitus (GDM) affects ;17% of pregnancies worldwide (1). In China, ;2.9 million pregnant women suffer from this disorder (2). GDM has long-term adverse outcomes in both mothers and offspring (3). Despite its serious complications, the diagnosis of GDM is

Summary The cardiac trabeculae are sheet-like structures extending from the myocardium that function to increase surface area. A lack of trabeculation causes embryonic lethality due to compromised cardiac function. To understand the cellular and molecular mechanisms of trabecular formation, we genetically labeled individual cardiomyocytes prior to trabeculation via the brainbow multicolor system, and traced and analyzed the labeled cells during trabeculation by whole-embryo clearing and imaging. The clones derived from labeled single cells displayed four different geometric patterns that are derived from different patterns of oriented cell division (OCD) and migration. Of the four types of clones, the inner, transmural, and mixed clones contributed to trabecular cardiomyocytes. Further studies showed that perpendicular OCD is an extrinsic asymmetric cell division that putatively contributes to trabecular regional specification. Furthermore, N-Cadherin deletion in labeled clones disrupted the clonal patterns. In summary, our data demonstrate that OCD contributes to trabecular morphogenesis and specification.