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author:("Chen, wiping")
1.  Persistent Noggin arrests cardiomyocyte morphogenesis and results in early in utero lethality 
Multiple BMP genes are expressed in the developing heart from the initiation to late-differentiation stages, and play pivotal roles in cardiovascular development. In this study, we investigated the requirement of BMP activity in heart development by transgenic over-expression of extracellular BMP antagonist Noggin.
Using Nkx2.5-Cre to drive lineage-restricted Noggin within cardiomyocyte progenitors, we show persistent Noggin arrests cardiac development at the linear heart stage. This is coupled with a significantly reduced cell proliferation rate, subsequent cardiomyocyte programmed cell death and reduction of downstream intracellular pSMAD1/5/8 expression. Noggin mutants exhibit reduced heartbeat which likely results in subsequent fully penetrant in utero lethality. Significantly, confocal and electron micrographic examination revealed considerably fewer contractile elements, as well as a lack of maturation of actin-myosin microfilaments. Molecular analysis demonstrated that ectopic Noggin-expressing regions in the early heart’s pacemaker region, failed to express the potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4 (Hcn4), resulting in an overall decrease in Hcn4 levels.
Combined, our results reveal a novel role for BMP signaling in the progression of heart development from the tubular heart stage to the looped stage via regulation of proliferation and promotion of maturation of the in utero heart’s contractile apparatus and pacemaker.
PMCID: PMC4344892  PMID: 25428115
mouse embryo; transgenic overexpression; Noggin; BMP; cardiomyocyte; congenital heart defects; proliferation; contractile apparatus; bradycardia
2.  Validity of COPD diagnoses reported through nationwide health insurance systems in the People’s Republic of China 
COPD is the fourth leading cause of death worldwide, with particularly high rates in the People’s Republic of China, even among never smokers. Large population-based cohort studies should allow for reliable assessment of the determinants of diseases, which is dependent on the quality of disease diagnoses. We assessed the validity of COPD diagnoses collected through electronic health records in the People’s Republic of China.
The CKB study recruited 0.5 million adults aged 30–79 years from ten diverse regions in the People’s Republic of China during the period 2004–2008. During 7 years of follow-up, 11,800 COPD cases were identified by linkage with mortality registries and the national health insurance system. We randomly selected ~10% of the reported COPD cases and then undertook an independent adjudication of retrieved hospital medical records in 1,069 cases.
Overall, these 1,069 cases were accrued over a 9-year period (2004–2013) involving 153 hospitals across ten regions. A diagnosis of COPD was confirmed in 911 (85%) cases, corresponding to a positive predictive value of 85% (95% confidence interval [CI]: 83%–87%), even though spirometry testing was not widely used (14%) in routine hospital care. The positive predictive value for COPD did not vary significantly by hospital ranking or calendar period, but was higher in men than women (89% vs 79%), at age ≥70 years than in younger people (88%, 95% CI: 85%–91%), and when the cases were reported from both death registry and health insurance systems (97%, 95% CI: 94%–100%). Among the remaining cases, 87 (8.1%) had other respiratory diseases (chiefly pneumonia and asthma; n=85) and 71 (6.6%) cases showed no evidence of any respiratory disease on their clinical records.
In the People’s Republic of China, COPD diagnoses obtained from electronic health records are of good quality and suitable for large population-based studies and do not warrant systematic adjudication of all the reported cases.
PMCID: PMC4780206  PMID: 27042034
COPD; events adjudication; COPD exacerbations; spirometry
4.  Electrocardiographic changes caused by lithium intoxication in an elderly patient 
SpringerPlus  2016;5:10.
Lithium intoxication can cause serious cardiac toxicity and is associated with electrocardiogram (ECG) changes. This paper described a case of a 76-year-old man who was lithium intoxicated and showed a variety of ECG abnormalities including sinus bradycardia, rapid atrial fibrillation, second-degree atrioventricular block and T wave changes. We monitored his ECGs during the after 3 days consecutively. After hemodialysis, his ECG abnormalities partially eased along with his serum lithium concentration decreased.
PMCID: PMC4700026  PMID: 26759749
Lithium; Intoxication; Arrhythmia; Electrocardiography
5.  Genetic Regulation of Sinoatrial Node Development and Pacemaker Program in the Venous Pole 
The definitive sinoatrial node (SAN), the primary pacemaker of the mammalian heart, develops from part of pro-pacemaking embryonic venous pole that expresses both Hcn4 and the transcriptional factor Shox2. It is noted that ectopic pacemaking activities originated from the myocardial sleeves of the pulmonary vein and systemic venous return, both derived from the Shox2+ pro-pacemaking cells in the venous pole, cause atrial fibrillation. However, the developmental link between the pacemaker properties in the embryonic venous pole cells and the SAN remains largely uncharacterized. Furthermore, the genetic program for the development of heterogeneous populations of the SAN is also under-appreciated. Here, we review the literature for a better understanding of the heterogeneous development of the SAN in relation to that of the sinus venosus myocardium and pulmonary vein myocardium. We also attempt to revisit genetic models pertinent to the development of pacemaker activities in the perspective of a Shox2-Nkx2-5 epistatic antagonism. Finally, we describe recent efforts in deciphering the regulatory networks for pacemaker development by genome-wide approaches.
PMCID: PMC4679406  PMID: 26682210
pacemaker development; venous pole; atrial fibrillation; SAN; pulmonary vein
6.  Contrasting male and female trends in tobacco-attributed mortality in China: evidence from successive nationwide prospective cohort studies 
Lancet (London, England)  2015;386(10002):1447-1456.
Chinese men now smoke more than a third of the world's cigarettes, following a large increase in urban then rural usage. Conversely, Chinese women now smoke far less than in previous generations. We assess the oppositely changing effects of tobacco on male and female mortality.
Two nationwide prospective studies 15 years apart recruited 220 000 men in about 1991 at ages 40–79 years (first study) and 210 000 men and 300 000 women in about 2006 at ages 35–74 years (second study), with follow-up during 1991–99 (mid-year 1995) and 2006–14 (mid-year 2010), respectively. Cox regression yielded sex-specific adjusted mortality rate ratios (RRs) comparing smokers (including any who had stopped because of illness, but not the other ex-smokers, who are described as having stopped by choice) versus never-smokers.
Two-thirds of the men smoked; there was little dependence of male smoking prevalence on age, but many smokers had not smoked cigarettes throughout adult life. Comparing men born before and since 1950, in the older generation, the age at which smoking had started was later and, particularly in rural areas, lifelong exclusive cigarette use was less common than in the younger generation. Comparing male mortality RRs in the first study (mid-year 1995) versus those in the second study (mid-year 2010), the proportional excess risk among smokers (RR-1) approximately doubled over this 15-year period (urban: RR 1·32 [95% CI 1·24–1·41] vs 1·65 [1·53–1·79]; rural: RR 1·13 [1·09–1·17] vs 1·22 [1·16–1·29]), as did the smoking-attributed fraction of deaths at ages 40–79 years (urban: 17% vs 26%; rural: 9% vs 14%). In the second study, urban male smokers who had started before age 20 years (which is now typical among both urban and rural young men) had twice the never-smoker mortality rate (RR 1·98, 1·79–2·19, approaching Western RRs), with substantial excess mortality from chronic obstructive pulmonary disease (COPD RR 9·09, 5·11–16·15), lung cancer (RR 3·78, 2·78–5·14), and ischaemic stroke or ischaemic heart disease (combined RR 2·03, 1·66–2·47). Ex-smokers who had stopped by choice (only 3% of ever-smokers in 1991, but 9% in 2006) had little smoking-attributed risk more than 10 years after stopping. Among Chinese women, however, there has been a tenfold intergenerational reduction in smoking uptake rates. In the second study, among women born in the 1930s, 1940s, 1950s, and since 1960 the proportions who had smoked were, respectively, 10%, 5%, 2%, and 1% (3097/30 943, 3265/62 246, 2339/97 344, and 1068/111 933). The smoker versus non-smoker RR of 1·51 (1·40–1·63) for all female mortality at ages 40–79 years accounted for 5%, 3%, 1%, and <1%, respectively, of all the female deaths in these four successive birth cohorts. In 2010, smoking caused about 1 million (840 000 male, 130 000 female) deaths in China.
Smoking will cause about 20% of all adult male deaths in China during the 2010s. The tobacco-attributed proportion is increasing in men, but low, and decreasing, in women. Although overall adult mortality rates are falling, as the adult population of China grows and the proportion of male deaths due to smoking increases, the annual number of deaths in China that are caused by tobacco will rise from about 1 million in 2010 to 2 million in 2030 and 3 million in 2050, unless there is widespread cessation.
Wellcome Trust, MRC, BHF, CR-UK, Kadoorie Charitable Foundation, Chinese MoST and NSFC
PMCID: PMC4691901  PMID: 26466050
7.  Generation of Shox2-Cre allele for tissue specific manipulation of genes in the developing heart, palate, and limb 
Genesis (New York, N.Y. : 2000)  2013;51(7):515-522.
Shox2 is expressed in several developing organs in a tissue specific manner in both mice and humans, including the heart, palate, limb, and nervous system. To better understand the spatial and temporal expression patterns of Shox2 and to systematically dissect the genetic cascade regulated by Shox2, we created Shox2-LacZ and Shox2-Cre knock-in mouse lines. We show that the Shox2-LacZ allele expresses beta-galactosidase reporter gene in a fashion that recapitulates the endogenous Shox2 expression pattern in developing organs, including the sinoatrial node (SAN), the anterior portion of the palate, and the proximal region of the limb bud. Conditional deletion of Shox2 in mice carrying the Shox2-Cre allele yielded SAN phenotypes that resemble conventional Shox2 knockout mice. Our results indicate that the Shox2-Cre allele offer a useful tool for tissue specific manipulation of genes in a number of developing organs, particularly in the developing SAN.
PMCID: PMC4560340  PMID: 23620086
Shox2; Cre; gene deletion; heart; palate; limb
8.  Altered FGF Signaling Pathways Impair Cell Proliferation and Elevation of Palate Shelves 
PLoS ONE  2015;10(9):e0136951.
In palatogenesis, palatal shelves are patterned along the mediolateral axis as well as the anteroposterior axis before the onset of palatal fusion. Fgf10 specifically expressed in lateral mesenchyme of palate maintains Shh transcription in lateral epithelium, while Fgf7 activated in medial mesenchyme by Dlx5, suppressed the expansion of Shh expression to medial epithelium. How FGF signaling pathways regulate the cell behaviors of developing palate remains elusive. In our study, we found that when Fgf8 is ectopically expressed in the embryonic palatal mesenchyme, the elevation of palatal shelves is impaired and the posterior palatal shelves are enlarged, especially in the medial side. The palatal deformity results from the drastic increase of cell proliferation in posterior mesenchyme and decrease of cell proliferation in epithelium. The expression of mesenchymal Fgf10 and epithelial Shh in the lateral palate, as well as the Dlx5 and Fgf7 transcription in the medial mesenchyme are all interrupted, indicating that the epithelial-mesenchymal interactions during palatogenesis are disrupted by the ectopic activation of mesenchymal Fgf8. Besides the altered Fgf7, Fgf10, Dlx5 and Shh expression pattern, the reduced Osr2 expression domain in the lateral mesenchyme also suggests an impaired mediolateral patterning of posterior palate. Moreover, the ectopic Fgf8 expression up-regulates pJak1 throughout the palatal mesenchyme and pErk in the medial mesenchyme, but down-regulates pJak2 in the epithelium, suggesting that during normal palatogenesis, the medial mesenchymal cell proliferation is stimulated by FGF/Erk pathway, while the epithelial cell proliferation is maintained through FGF/Jak2 pathway.
PMCID: PMC4558018  PMID: 26332583
9.  Directed Bmp4 expression in neural crest cells generates a genetic model for the rare human bony syngnathia birth defect 
Developmental biology  2014;391(2):170-181.
Congenital bony syngnathia, a rare but severe human birth defect, is characterized by bony fusion of the mandible to the maxilla. However, the genetic mechanisms underlying this birth defect are poorly understood, largely due to limitation of available animal models. Here we present evidence that transgenic expression of Bmp4 in neural crest cells causes a series of craniofacial malformations in mice, including a bony fusion between the maxilla and hypoplastic mandible, resembling the bony syngnathia syndrome in humans. In addition, the anterior portion of the palatal shelves emerged from the mandibular arch instead of the maxilla in the mutants. Gene expression assays showed an altered expression of several facial patterning genes, including Hand2, Dlx2, Msx1, Barx1, Foxc2 and Fgf8, in the maxillary and mandibular processes of the mutants, indicating mis-patterned cranial neural crest (CNC) derived cells in the facial region. However, despite of formation of cleft palate and ectopic cartilage, forced expression of a constitutively active form of BMP receptor-Ia (caBmprIa) in CNC lineage did not produce the syngnathia phenotype, suggesting a non-cell autonomous effect of the augmented BMP4 signaling. Our studies demonstrate that aberrant BMP4-mediated signaling in CNC cells leads to mis-patterned facial skeleton and congenital bony syngnathia, and suggest an implication of mutations in BMP signaling pathway in human bony syngnathia.
PMCID: PMC4089042  PMID: 24785830
Bmp signaling; cranial neural crest; syngnathia; cleft palate; craniofacial patterning
10.  Molecular Signatures of Major Depression 
Current Biology  2015;25(9):1146-1156.
Adversity, particularly in early life, can cause illness. Clues to the responsible mechanisms may lie with the discovery of molecular signatures of stress, some of which include alterations to an individual’s somatic genome. Here, using genome sequences from 11,670 women, we observed a highly significant association between a stress-related disease, major depression, and the amount of mtDNA (p = 9.00 × 10−42, odds ratio 1.33 [95% confidence interval [CI] = 1.29–1.37]) and telomere length (p = 2.84 × 10−14, odds ratio 0.85 [95% CI = 0.81–0.89]). While both telomere length and mtDNA amount were associated with adverse life events, conditional regression analyses showed the molecular changes were contingent on the depressed state. We tested this hypothesis with experiments in mice, demonstrating that stress causes both molecular changes, which are partly reversible and can be elicited by the administration of corticosterone. Together, these results demonstrate that changes in the amount of mtDNA and telomere length are consequences of stress and entering a depressed state. These findings identify increased amounts of mtDNA as a molecular marker of MD and have important implications for understanding how stress causes the disease.
•Amount of mtDNA is increased, and telomeric DNA is shortened in major depression•Both changes can be induced with stress but are contingent on the depressed state•Changes are tissue specific and in part due to glucocorticoid secretion•Changes are in part reversible and represent switches in metabolic strategy
Cai et al. found increases in mtDNA and a reduction in telomeric DNA in cases of major depression using whole-genome sequencing. Both changes are depression state dependent. Mice exposed to chronic stress or glucorticoids showed that these changes reflect switches in metabolic strategy and are tissue specific and partial reversible.
PMCID: PMC4425463  PMID: 25913401
11.  Efficacy and Safety of Tangshen Formula on Patients with Type 2 Diabetic Kidney Disease: A Multicenter Double-Blinded Randomized Placebo-Controlled Trial 
PLoS ONE  2015;10(5):e0126027.
Persons with diabetes are at high risk of developing diabetic kidney disease (DKD), which is associated with high morbidity and mortality. Current drug therapies for DKD, such as angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), are not entirely satisfactory. This study aimed to evaluate the additional benefit and safety of the Chinese herbal granule Tangshen Formula (TSF) in treating DKD.
The study was designed as a six-center randomized, double-blind, placebo-controlled trial. From April 2007 through December 2009, 180 patients with DKD were enrolled. In addition to conventional treatment with ACEIs or ARBs, 122 participants were randomly assigned to receive TSF and 58 participants to receive placebo for 24 weeks. Primary outcome was urinary protein level, measured by urinary albumin excretion rate (UAER) for participants with microalbuminuria, 24-hour urinary protein (24h UP) for participants with macroalbuminuria. Secondary outcomes included renal function, serum lipids, quality of life, symptoms, and adverse events.
After 24 weeks of treatment, no statistically significant difference in UAER (TSF −19.53 μg/min compared with placebo −7.01 μg/min, with a mean difference of −12.52 μg/min; 95%CI, −68.67 to 43.63, P = 0.696) was found between TSF and placebo groups. However, TSF displayed a statistically significant decrease in 24h UP (TSF−0.21 g compared with placebo 0.36 g, with a mean difference of −0.57g; 95%CI, −1.05 to −0.09, P = 0.024). Estimated glomerular filtration rate (eGFR) was improved in both patients with microalbuminuria and macroalbuminuria, with a mean difference of 15.51 ml/min/1.73 m2 (95%CI, 3.71 to 27.31), 9.01 ml/min/1.73 m2 (95%CI, −0.10 to 18.13), respectively. Other secondary outcomes showed no statistically significant difference between groups or in the incidence of adverse events.
Based on conventional treatments, TSF appears to provide additional benefits compared with placebo in decreasing proteinuria and improving eGFR in DKD patients with macroalbuminuria. Nevertheless, further study is needed to evaluate TSF treating patients with microalbuminuria.
Trial Registration
Chinese Clinical Trial Registry ChiCTR-TRC-10000843
PMCID: PMC4418676  PMID: 25938778
12.  Dinosaur’s feather and chicken’s tooth? Tissue engineering of the integument 
The integument forms the interface between animals and the environment. During evolution, diverse integument and integument appendages have evolved to adapt animals to different niches. The formation of these different integument forms is based on the acquisition of novel developmental mechanisms. This is the way Nature does her tissue/organ engineering and experiments. To do tissue engineering of the integument in the new century for medical applications, we need to learn more principles from developmental and evolutionary studies. A novel diagram showing the evolution and development of integument complexity is presented, and the molecular pathways involved discussed. We then discuss two examples in which the gain and loss of appendages are modulated: transformation of avian scale epidermis into feathers with mutated beta catenin, and induction of chicken tooth like appendages with FGF, BMP and feather mesenchyme.
PMCID: PMC4386664  PMID: 11399531
dinosaur; evolution; feather; hair; stem cells; teeth; tissue engineer
13.  The Impact of Matrix Metalloproteinase 2 on Prognosis and Clinicopathology of Breast Cancer Patients: A Systematic Meta-Analysis 
PLoS ONE  2015;10(3):e0121404.
Matrix metalloproteinase 2 (MMP-2) plays a crucial role in the progression of breast cancer (BC). The prognostic role of MMP-2 expression in BC patients has been widely reported, but the results were inconsistent. Thus, a meta-analysis was conducted to gain a better insight into the impact of MMP-2 expression on survival and clinicopathological features of BC patients.
Identical search strategies were used to search relevant literatures in electronic databases update to August 1, 2014. Individual hazard ratios (HRs) and odds ratios (ORs) with their 95% confidence intervals (CIs) were extracted and pooled to evaluate the strength of the association between positive MMP-2 expression and survival results and clinicopathological features of BC patients. Begg’s tests, Egger’s tests and funnel plots were used to evaluate publication bias. Heterogeneity and sensitivity analysis were also assessed. All the work was completed using STATA.
Pooled HRs and 95% CIs suggested that MMP-2 expression had an unfavorable impact on both OS (HR: 1.53, 95% CI: 1.29–1.82) and DFS/RFS/DDFS (HR: 1.41, 95% CI: 1.07–1.86) in BC patients. Furthermore, MMP-2 expression was significantly associated with lymph node metastasis (positive vs negative: OR 1.91, 95% CI 1.17–3.12).
In conclusion, positive MMP-2 expression might be a significant predictive factor for poor prognosis in patients with BC.
PMCID: PMC4376789  PMID: 25816052
14.  Nephrokeli, a Chinese Herbal Formula, May Improve IgA Nephropathy through Regulation of the Sphingosine-1-Phosphate Pathway 
PLoS ONE  2015;10(1):e0116873.
Nephrokeli (NPKL) is a Chinese herbal formula that has been used to treat patients with IgA nephropathy (IgAN) for improvement of proteinuria and kidney injury. However, the mechanism remains unclear. Sphingosine-1-phosphate (S1P) and its receptors S1PR2 and S1PR3 are known to play an important role in kidney disease. Here, we tested whether NPKL is able to regulate the S1P pathway in the kidney of IgAN rats. Four groups of rats were included in the study: Control, IgAN, IgAN treated with losartan, and IgAN treated with NPKL. The IgAN model was generated by injection of bovine serum albumin and staphylococcus enterotoxin B. We found that IgAN rats had increased staining for proliferating cell nuclear antigen (PCNA) in the mesangial area and increased mRNA and protein levels of S1PR2 and S1PR3 in the kidney compared to control rats. Connective tissue growth factor (CTGF), a downstream growth factor in the S1P pathway, was also elevated in the kidney of IgAN rats. Treatment with either NPKL or losartan was able to reduce PCNA staining and the expression of both S1PR2 and S1PR3 in the kidney of IgAN rats. However, NPKL (but not losartan treatment) reduced the expression of CTGF in the kidney of IgAN rats. In addition, we treated rat mesangial cells with sera collected from either NPKL-treated rats or control rats and found that NPKL-serum was able to reduce S1P-induced mesangial cell proliferation and the expression of S1PR2/S1PR3 and CTGF. NPKL also attenuates expression of fibrosis, inflammation, and oxidative stress markers in the kidney of IgAN rats. Our studies provide the mechanism by which NPKL attenuates kidney injury in IgAN rats.
PMCID: PMC4310606  PMID: 25633986
15.  Depression, anxiety, and prevalent diabetes in the Chinese population: Findings from the China Kadoorie Biobank of 0.5 million people 
Journal of psychosomatic research  2013;75(6):511-517.
Despite previous investigation, uncertainty remains about the nature of the associations of major depression (MD) with type 2 diabetes mellitus (T2DM), particularly in adult Chinese, and the relevance of generalized anxiety disorder (GAD) for T2DM.
Cross-sectional data from the China Kadoorie Biobank Study, a sample of approximately 500,000 adults from 10 geographically defined regions of China, were analyzed. Past year MD and GAD were assessed using the Composite International Diagnostic Inventory. T2DM was defined as either having self-reported physician diagnosis of diabetes at age 30 or later (“clinically-identified” cases) or having a non-fasting blood glucose ≥11.1 mmol/L or fasting blood glucose ≥7.0 mmol/L but no prior diagnosis of diabetes (“screen-detected” cases). Logistic regression was used to assess the relationship between MD and GAD with clinically-identified and screen-detected T2DM, adjusting for demographic characteristics and health behaviors.
The prevalence of T2DM was 5.3% (3.2% clinically-identified and 2.1% screen-detected). MD was significantly associated with clinically-identified T2DM (Odds ratio [OR]: 1.75, 95% Confidence Interval (CI): 1.47 – 2.08), but not with screen-detected T2DM (OR: 1.18, 95% CI: 0.92 – 1.51). GAD was associated with both clinically-identified (OR: 2.14, 95% CI: 1.60 – 2.88) and screen-detected (OR: 1.44, 95% CI: 0.99 – 2.08) T2DM. The relationship between MD and GAD with T2DM was moderated by obesity.
MD is associated with clinically-identified, but not screen-detected T2DM. GAD is associated with both clinically-identified and screen-detected T2DM. The relationship between MD and T2DM is strongest among those who are not obese.
PMCID: PMC3919064  PMID: 24290039
anxiety; culture; depression; epidemiology; type 2 diabetes
16.  BMP-FGF Signaling Axis Mediates Wnt-Induced Epidermal Stratification in Developing Mammalian Skin 
PLoS Genetics  2014;10(10):e1004687.
Epidermal stratification of the mammalian skin requires proliferative basal progenitors to generate intermediate cells that separate from the basal layer and are replaced by post-mitotic cells. Although Wnt signaling has been implicated in this developmental process, the mechanism underlying Wnt-mediated regulation of basal progenitors remains elusive. Here we show that Wnt secreted from proliferative basal cells is not required for their differentiation. However, epidermal production of Wnts is essential for the formation of the spinous layer through modulation of a BMP-FGF signaling cascade in the dermis. The spinous layer defects caused by disruption of Wnt secretion can be restored by transgenically expressed Bmp4. Non-cell autonomous BMP4 promotes activation of FGF7 and FGF10 signaling, leading to an increase in proliferative basal cell population. Our findings identify an essential BMP-FGF signaling axis in the dermis that responds to the epidermal Wnts and feedbacks to regulate basal progenitors during epidermal stratification.
Author Summary
Epidermis, a thin layer of stratified epithelium forming the outmost surface of the skin, provides the crucial function to protect animals from environmental insults, such as bacterial pathogens and water loss. This barrier function is established in embryogenesis, during which single layered epithelial cells differentiate into distinct layers of keratinocytes. Many human genetic diseases are featured with epidermal disruption, affecting at least one in five patients. Skin regeneration and future therapeutics require a thorough understanding of the molecular mechanisms underlying epidermal stratification. Wnt ligands have been implicated in hair follicle induction during skin development and self-renewal of stem cells in the interfollicular epidermis of adult skin; however, little is known about the mechanism of how Wnt signaling controls epidermal stratification during embryogenesis. In this study, by using a genetic mouse model to disrupt Wnt production in skin development, we found that signaling of epidermal Wnt in the dermis initiate mesenchymal responses by activating a Bone Morphogenetic Protein (BMP) and Fibroblast growth factor (FGF) signaling cascade, and this activation is required for feedback regulations in the embryonic epidermis to control stratification. Our findings identify a genetic hierarchy of signaling essential for epidermal-mesenchymal interactions, and promote our understanding of mammalian skin development.
PMCID: PMC4199507  PMID: 25329657
17.  Enhanced BMP signaling prevents degeneration and leads to endochondral ossification of Meckel’s cartilage in mice 
Developmental biology  2013;381(2):301-311.
Meckel’s cartilage is a transient supporting tissue of the embryonic mandible in mammals, and disappears by taking different ultimate cell fate along the distal-proximal axis, with the majority (middle portion) undergoing degeneration and chondroclastic resorption. While a number of factors have been implicated in the degeneration and resorption processes, signaling pathways that trigger this degradation are currently unknown. BMP signaling has been implicated in almost every step of chondrogenesis. In this study, we used Noggin mutant mice as a model for gain-of-BMP signaling function to investigate the function of BMP signaling in Meckel’s cartilage development, with a focus on the middle portion. We showed that Bmp2 and Bmp7 are expressed in early developing Meckels’ cartilage, but their expression disappears thereafter. In contrast, Noggin is expressed constantly in Meckel’s cartilage throughout the entire gestation period. In the absence of Noggin, Meckel’s cartilage is significantly thickened attributing to dramatically elevated cell proliferation rate associated with enhanced phosphorylated Smad1/5/8 expression. Interestingly, instead of taking a degeneration fate, the middle portion of Meckel’s cartilage in Noggin mutants undergoes chondrogenic differentiation and endochondral ossification contributing to the forming mandible. Chondrocyte-specific expression of a constitutively active form of BMPRIa but not BMPRIa leads enlargement of Meckel’s cartilage, phenocopying the consequence of Noggin deficiency. Our results demonstrate that elevated BMP signaling prevents degeneration and leads to endochondral ossification of Meckel’s cartilage, and support the idea that withdrawal of BMP signaling is required for normal Meckel’s cartilage development and ultimate cell fate.
PMCID: PMC3777720  PMID: 23891934
BMP signaling; Noggin; BmprIa; Meckel’s cartilage; development; differentiation
18.  Smoking and Major Depressive Disorder in Chinese Women 
PLoS ONE  2014;9(9):e106287.
To investigate the risk factors that contribute to smoking in female patients with major depressive disorder (MDD) and the clinical features in depressed smokers.
We examined the smoking status and clinical features in 6120 Han Chinese women with MDD (DSM-IV) between 30 and 60 years of age across China. Logistic regression was used to determine the association between clinical features of MDD and smoking status and between risk factors for MDD and smoking status.
Among the recurrent MDD patients there were 216(3.6%) current smokers, 117 (2.0%) former smokers and 333(5.6%) lifetime smokers. Lifetime smokers had a slightly more severe illness, characterized by more episodes, longer duration, more comorbid illness (panic and phobias), with more DSM-IV A criteria and reported more symptoms of fatigue and suicidal ideation or attempts than never smokers. Some known risk factors for MDD were also differentially represented among smokers compared to non-smokers. Smokers reported more stressful life events, were more likely to report childhood sexual abuse, had higher levels of neuroticism and an increased rate of familial MDD. Only neuroticism was significantly related to nicotine dependence.
Although depressed women smokers experience more severe illness, smoking rates remain low in MDD patients. Family history of MDD and environmental factors contribute to lifetime smoking in Chinese women, consistent with the hypothesis that the association of smoking and depression may be caused by common underlying factors.
PMCID: PMC4152240  PMID: 25180682
19.  Exploring the effects of gene dosage on mandible shape in mice as a model for studying the genetic basis of natural variation 
Development genes and evolution  2013;223(5):279-287.
Mandible shape in the mouse is a complex trait that is influenced by many genetic factors. However, little is known about the action of single genes on adult mandible shape so far, since most developmentally relevant genes are already required during embryogenesis, i.e. knockouts lead to embryonic death or severe deformations, before the mandible is fully formed. We employ here a geometric morphometrics approach to identify subtle phenotypic differences caused by dosage effects of candidate genes. We use mouse strains with specific gene modifications (knock-outs and knock-ins) to compare heterozygous animals with controls from the same stock, which is expected to be equivalent to a change of gene expression of the respective locus. Such differences in expression level are also likely to occur as part of the natural variation. We focus on Bmp pathway genes (Bmp4, its antagonist Noggin and combinations of Bmp5–7 genotypes), but include also two other developmental control genes suspected to affect mandible development in some way (Egfr and Irf6). In addition, we study effects of Hoxd13, as well as an extracellular matrix constituent (Col2a1). We find that subtle, but significant shape differences are caused by differences in gene dosage of several of these genes. The changes seen for Bmp4 and Noggin are partially compatible with the action of these genes known from birds and fish. We find significant shape changes also for Hoxd13, although this gene has so far only been implicated in skeletal patterning processes of the limbs. Comparing the effect sizes of gene dosage changes to the variation found in natural populations of mice as well as QTL effects on mandible shape, we find that the effect sizes caused by gene dosage changes are at the lower end of the spectrum of natural variation, but larger than the average additive effects found in QTL studies. We conclude that studying gene dosage effects have the potential to provide new insights into aspects of craniofacial development, variation and evolution.
PMCID: PMC4013528  PMID: 23563729
shape analysis; morphometry; dosage effects; mandible development; Mus musculus
20.  BMPRIA Mediated Signaling Is Essential for Temporomandibular Joint Development in Mice 
PLoS ONE  2014;9(8):e101000.
The central importance of BMP signaling in the development and homeostasis of synovial joint of appendicular skeleton has been well documented, but its role in the development of temporomandibular joint (TMJ), also classified as a synovial joint, remains completely unknown. In this study, we investigated the function of BMPRIA mediated signaling in TMJ development in mice by transgenic loss-of- and gain-of-function approaches. We found that BMPRIA is expressed in the cranial neural crest (CNC)-derived developing condyle and glenoid fossa, major components of TMJ, as well as the interzone mesenchymal cells. Wnt1-Cre mediated tissue specific inactivation of BmprIa in CNC lineage led to defective TMJ development, including failure of articular disc separation from a hypoplastic condyle, persistence of interzone cells, and failed formation of a functional fibrocartilage layer on the articular surface of the glenoid fossa and condyle, which could be at least partially attributed to the down-regulation of Ihh in the developing condyle and inhibition of apoptosis in the interzone. On the other hand, augmented BMPRIA signaling by Wnt1-Cre driven expression of a constitutively active form of BmprIa (caBmprIa) inhibited osteogenesis of the glenoid fossa and converted the condylar primordium from secondary cartilage to primary cartilage associated with ectopic activation of Smad-dependent pathway but inhibition of JNK pathway, leading to TMJ agenesis. Our results present unambiguous evidence for an essential role of finely tuned BMPRIA mediated signaling in TMJ development.
PMCID: PMC4122352  PMID: 25093411
21.  Pten loss induces autocrine FGF signaling to promote skin tumorigenesis 
Cell reports  2014;6(5):818-826.
Inactivation of the Pten tumor suppressor negatively regulates the PI3K-mTOR pathway. In a model of cutaneous squamous cell carcinoma (SCC), we demonstrate that deletion of Pten strongly elevates Fgf10 protein levels without increasing Fgf10 transcription in vitro and in vivo. The translational activation of Fgf10 by Pten deletion is reversed by genetic disruption of the mTORC1 complex, which also prevents skin tumorigenesis in Pten mutants. We further show that ectopic expression of Fgf10 causes skin papillomas, while Pten deletion-induced skin tumors are inhibited by epidermal deletion of Fgfr2. Collectively, our data identify autocrine activation of FGF signaling as an essential mechanism in promoting Pten-deficient skin tumors.
PMCID: PMC4080841  PMID: 24582960
22.  A Compact Methodology to Understand, Evaluate, and Predict the Performance of Automatic Target Recognition 
Sensors (Basel, Switzerland)  2014;14(7):11308-11350.
This paper offers a compacted mechanism to carry out the performance evaluation work for an automatic target recognition (ATR) system: (a) a standard description of the ATR system's output is suggested, a quantity to indicate the operating condition is presented based on the principle of feature extraction in pattern recognition, and a series of indexes to assess the output in different aspects are developed with the application of statistics; (b) performance of the ATR system is interpreted by a quality factor based on knowledge of engineering mathematics; (c) through a novel utility called “context-probability” estimation proposed based on probability, performance prediction for an ATR system is realized. The simulation result shows that the performance of an ATR system can be accounted for and forecasted by the above-mentioned measures. Compared to existing technologies, the novel method can offer more objective performance conclusions for an ATR system. These conclusions may be helpful in knowing the practical capability of the tested ATR system. At the same time, the generalization performance of the proposed method is good.
PMCID: PMC4168426  PMID: 24967605
automatic target recognition; performance evaluation; performance prediction
23.  Therapeutic use of traditional Chinese herbal medications for chronic kidney diseases 
Kidney international  2013;84(6):1108-1118.
Traditional Chinese herbal medications (TCHM) are frequently used in conjunction with western pharmacotherapy for treatment of chronic kidney diseases (CKD) in China and many other Asian countries. The practice of traditional Chinese medicine is guided by cumulative empiric experience. Recent in vitro and animal studies have confirmed the biological activity and therapeutic effects of several TCHM in CKD. However, the level of evidence supporting TCHM is limited to small, non-randomized trials. Due to variations in the prescription pattern of TCHM and the need for frequent dosage adjustment, which are inherent to the practice of traditional Chinese medicine, it has been challenging to design and implement large randomized clinical trials of TCHM. Several TCHM are associated with significant adverse effects, including nephrotoxicity. However, reporting of adverse effects associated with TCHM has been inadequate. To fully realize the therapeutic use of TCHM in CKD we need molecular studies to identify active ingredients of TCHM and their mechanism of action, rigorous pharmacologic studies to determine the safety and meet regulatory standards required for clinical therapeutic agents, and well-designed clinical trials to provide evidence-based support of their safety and efficacy.
PMCID: PMC3812398  PMID: 23868014
Kidney disease; Chinese herb medications; toxicity; alternative medicine; drug discovery
24.  Phosphorylation of Shox2 Is Required for Its Function to Control Sinoatrial Node Formation 
Inactivation of Shox2, a member of the short‐stature homeobox gene family, leads to defective development of multiple organs and embryonic lethality as a result of cardiovascular defects, including bradycardia and severe hypoplastic sinoatrial node (SAN) and sinus valves, in mice. It has been demonstrated that Shox2 regulates a genetic network through the repression of Nkx2.5 to maintain the fate of the SAN cells. However, the functional mechanism of Shox2 protein as a transcriptional repressor on Nkx2.5 expression remains completely unknown.
Methods and Results
A specific interaction between the B56δ regulatory subunit of PP2A and Shox2a, the isoform that is expressed in the developing heart, was demonstrated by yeast 2‐hybrid screen and coimmunoprecipitation. Western blotting and immunohistochemical assays further confirmed the presence of phosphorylated Shox2a (p‐Shox2a) in cell culture as well as in the developing mouse and human SAN. Site‐directed mutagenesis and in vitro kinase assays identified Ser92 and Ser110 as true phosphorylation sites and substrates of extracellular signal‐regulated kinase 1 and 2. Despite that Shox2a and its phosphorylation mutants possessed similar transcriptional repressive activities in cell cultures when fused with Gal4 protein, the mutant forms exhibited a compromised repressive effect on the activity of the mouse Nkx2.5 promoter in cell cultures, indicating that phosphorylation is required for Shox2a to repress Nkx2.5 expression specifically. Transgenic expression of Shox2a, but not Shox2a‐S92AS110A, mutant in the developing heart resulted in down‐regulation of Nkx2.5 in wild‐type mice and rescued the SAN defects in the Shox2 mutant background. Last, we demonstrated that elimination of both phosphorylation sites on Shox2a did not alter its nuclear location and dimerization, but depleted its capability to bind to the consensus sequences within the Nkx2.5 promoter region.
Our studies reveal that phosphorylation is essential for Shox2a to repress Nkx2.5 expression during SAN development and differentiation.
PMCID: PMC4309068  PMID: 24847033
DNA binding; Nkx2.5 repression; pacemaking; phosphorylation; SAN development; Shox2
25.  Bioengineering of a human whole tooth: progress and challenge 
Cell Regeneration  2014;3(1):8.
A major challenge in stem cell-based bioengineering of an implantable human tooth is to identify appropriate sources of postnatal stem cells that are odontogenic competent as the epithelial component due to the lack of enamel epithelial cells in adult teeth. In a recent issue (2013, 2:6) of Cell Regeneration, Cai and colleagues reported that epithelial sheets derived from human induced pluripotent stem cells (iPSCs) can functionally substitute for tooth germ epithelium to regenerate tooth-like structures, providing an appealing stem cell source for future human tooth regeneration.
PMCID: PMC4230350  PMID: 25408887

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