Micro- and Ultrastructural Characterization of Age-Related Changes at the Anterior Cruciate Ligament-to-Bone Insertion

There remains a lack of understanding of the structural changes that occur across the complex, multitissue anterior cruciate ligament (ACL)-to-bone insertion as a function of aging. The objective of this study is to provide a multiscale comparison of matrix properties across the skeletally immature and mature ACL-to-bone insertion. Using complementary imaging methods, micro- and ultrastructural analysis of the insertion revealed that collagen fiber orientation at the interface changes with age, though the degree of collagen organization is maintained over time. These changes are accompanied by a decrease in collagen fibril density and are likely driven by physiological loading. Mineral crystal structure and crystallinity are conserved over time, despite regional differences in crystallinity between the interface and bone. This suggests that mineral chemistry is established early in development and underscores its important functional role. Collectively, these findings provide new insights into interface development and set critical design benchmarks for integrative soft tissue repair.

DC-SIGN promotes allergen uptake and activation of dendritic cells in patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common inflammatory skin disease, concomitant with allergic reactions to allergens. However, the exact mechanisms of allergen-induced immune responses in AD are not clear. The aim of this study is to explore the role of DC-SIGN in capturing and processing glycan-containing allergens and in the subsequent DC activation and T helper cell polarization in AD patients.

METHODS

DC-SIGN expression on DCs from AD patients was analysed by confocal microscopy and flow cytometry. DC-SIGN binding to common allergens was determined by ELISA. Activation of monocyte-derived dendritic cells (Mo-DCs) by allergens was analysed by evaluation of pro-inflammatory cytokines production, and their impact on T-cell responses was investigated by a DC-T cell coculture.

RESULTS

DC-SIGN expression was higher on DCs in the lesional skin of AD patients compared with that of healthy controls and was correlated with disease severity. DC-SIGN could bind to many common allergens including house dust mite allergen (Der p2) and egg white allergen (Gal d2). Mo-DCs showed measurable expression of DC-SIGN and a concentration-dependent uptake of Der p2 and Gal d2, which was inhibited by mannan and anti-DC-SIGN Abs. Der p2 and Gal d2 induced the production of pro-inflammatory cytokines, including TNF-α and IL-6, by DCs from AD patients and facilitated Th2 and Th22 cell polarization.

CONCLUSIONS

Binding of common allergens by DC-SIGN on DCs may initiate allergen sensitization of AD or provoke the relapse of AD. Regulating the allergen-DC-SIGN interaction might be a promising strategy to prevent or intervene in the progress of AD.

Medical therapies for heavy menstrual bleeding in women with uterine fibroids: a retrospective analysis of a large commercially insured population in the USA

OBJECTIVES

To report patterns and patient characteristics associated with initiation of and persistence with medical therapies for uterine fibroid-related heavy menstrual bleeding.

DESIGN

Retrospective cohort study.

SETTING

US commercial insurance claims database.

POPULATION

41 561 women aged 18-54 years with uterine fibroids and heavy menstrual bleeding who initiated medical therapies from January 2000 through December 2013.

METHOD

Multinomial logistic regression was used to assess patient characteristics associated with initiation and persistence. Cox proportional hazards regression was used on propensity score-matched cohorts to examine change from index medication.

MAIN OUTCOMES MEASURES

Initiation of and persistence with four first-line medical therapies: short- and long-acting reversible contraceptive steroids, leuprolide acetate, and tranexamic acid.

RESULTS

Most women (79.4%) took short-acting reversible contraceptive steroids as first-line therapy (index medication), whereas 9.5%, 8.5%, and 2.7% used long-acting reversible contraceptive steroids, leuprolide acetate, and tranexamic acid, respectively. During follow-up, 16 594 women (39.9%) switched to nonindex medication (18.4%) or procedural treatment (81.6%). In comparison with women taking short-acting steroids, those receiving long-acting steroids were less likely to switch [hazard ratio (HR) 0.84, 95% CI 0.79-0.91], whereas women taking leuprolide acetate (HR 2.44, 95% CI 2.27-2.62) or tranexamic acid (HR 1.44, 95% CI 1.26-1.65) were more likely to switch. Older age, emergency department visits, anaemia, and inflammatory disease diagnoses at baseline were associated with increased probability of discontinuing the index medication or switching to another therapy.

CONCLUSIONS

Women with uterine fibroid-related heavy menstrual bleeding were more likely to persist with their initial therapy of long-acting reversible contraceptive steroid compared with other medical options.

TWEETABLE ABSTRACT

80% women with fibroid-related heavy menstrual bleeding use SARC, but LARC users are more persistent.

Risk factors and clinical outcomes for carbapenem-resistant Enterobacteriaceae nosocomial infections

This study was aimed to determine the risk factors of Carbapenem-resistant Enterobacteriaceae (CRE) nosocomial infections and assess the clinical outcomes. A case-case-control design was used to compare two groups of case patients with control patients from March 2010 to November 2014 in China. Risk factors for the acquisition of CRE infections and clinical outcomes were analyzed by univariable and multivariable analysis. A total of 94 patients with CRE infections, 93 patients with Carbapenem-susceptible Enterobacteriaceae (CSE) infections, and 93 patients with organisms other than Enterobacteriaceae infections were enrolled in this study. Fifty-five isolates were detected as the carbapenemase gene. KPC-2 was the most common carbapenemase (65.5 %, 36/55), followed by NDM-1 (16.4 %, 9/55), IMP-4 (14.5 %, 8/55), NDM-5 (1.8 %, 1/55), and NDM-7 (1.8 %, 1/55). Multivariable analysis implicated previous use of third or fourth generation cephalosporins (odds ratio [OR], 4.557; 95 % confidence interval [CI], 1.971-10.539; P < 0.001) and carbapenems (OR, 4.058; 95 % CI, 1.753-9.397; P = 0.001) as independent risk factors associated with CRE infection. The in-hospital mortality of the CRE group was 57.4 %. In the population of CRE infection, presence of central venous catheters (OR, 4.464; 95 % CI, 1.332-14.925; P = 0.015) and receipt of immunosuppressors (OR, 7.246; 95 % CI, 1.217-43.478; P = 0.030) were independent risk factors for mortality. Appropriate definitive treatment (OR, 0.339; 95 % CI, 0.120-0.954; P = 0.040) was a protective factor for in-hospital death of CRE infection. Kaplan-Meier curves of the CRE group had the shortest survival time compared with the other two groups. Survival time of patients infected with Enterobacteriaceae with a high meropenem MIC (≥8 mg/L) was shorter than that of patients with a low meropenem MIC (2,4, and ≤ 1 mg/L). In conclusion, CRE nosocomial infections are associated with prior exposure to third or fourth generation cephalosporins and carbapenems. Patients infected with CRE had poor outcome and high mortality, especially high meropenem MIC (≥8 mg/L). Appropriate definitive treatment to CRE infections in the patient is essential.

Glucose and lipid effects of the ileal apical sodium-dependent bile acid transporter inhibitor GSK2330672: double-blind randomized trials with type 2 diabetes subjects taking metformin

AIMS

To investigate the pharmacodynamics, pharmacokinetics and safety/tolerability of blocking reuptake of bile acids using the inhibitor GSK2330672 (GSK672) in patients with type 2 diabetes (T2D).

METHODS

Subjects with T2D taking metformin were enrolled in two studies in which they took metformin 850 mg twice daily for 2 weeks prior to and during the randomized treatment periods. In the first crossover study (n = 15), subjects received GSK672 45 mg, escalating to 90 mg, twice daily, or placebo for 7 days. The second parallel-group study (n = 75) investigated GSK672 10-90 mg twice daily, placebo or sitagliptin for 14 days.

RESULTS

In both studies, GSK672 reduced circulating bile acids and increased serum 7-α-hydroxy-4-cholesten-3-one (C4), an intermediate in the hepatic synthesis of bile acids. Compared with placebo, in the parallel-group study 90 mg GSK672 twice daily reduced fasting plasma glucose [FPG; -1.21 mmol/l; 95% confidence interval (CI) -2.14, -0.28] and weighted-mean glucose area under the curve (AUC)0-24 h (-1.33 mmol/l; 95% CI -2.30, -0.36), as well as fasting and weighted-mean insulin AUC0 -24 h . GSK672 also reduced cholesterol (LDL, non-HDL and total cholesterol) and apolipoprotein B concentrations; the maximum LDL cholesterol reduction was ∼40%. There was no change in HDL cholesterol but there was a trend towards increased fasting triglyceride levels in the GSK672 groups compared with placebo. In both studies, the most common adverse events associated with GSK672 were gastrointestinal, mostly diarrhoea (22-100%), which appeared to be independent of dose.

CONCLUSIONS

In subjects with T2D on metformin, GSK672 improved glucose and lipids, but there was a high incidence of gastrointestinal adverse events.

Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography

We present an ultrahigh-resolution spectral domain optical coherence tomography (OCT) system in 800 nm with a low-noise supercontinuum source (SC) optimized for myocardial imaging. The system was demonstrated to have an axial resolution of 2.72  μm with a large imaging depth of 1.78 mm and a 6-dB falloff range of 0.89 mm. The lateral resolution (5.52  μm) was compromised to enhance the image penetration required for myocardial imaging. The noise of the SC source was analyzed extensively and an imaging protocol was proposed for SC-based OCT imaging with appreciable contrast. Three-dimensional datasets were acquired ex vivo on the endocardium side of tissue specimens from different chambers of fresh human and swine hearts. With the increased resolution and contrast, features such as elastic fibers, Purkinje fibers, and collagen fiber bundles were observed. The correlation between the structural information revealed in the OCT images and tissue pathology was discussed as well.

Multiparametric Magnetic Resonance Imaging in the Diagnosis of Prostate Cancer: A Systematic Review

A systematic review was conducted to investigate the use of multiparametric magnetic resonance imaging (MPMRI) followed by targeted biopsy in the diagnosis of clinically significant prostate cancer (CSPC) and to compare it with transrectal ultrasound-guided (TRUS-guided) systematic biopsy in patients with an elevated risk of prostate cancer who are either biopsy-naive or who have a previous negative TRUS-guided biopsy. MEDLINE, PubMed and EMBASE (1997 to April 2014), the Cochrane Library and six relevant conferences were searched to find eligible studies. Search terms indicative of 'prostate cancer' and 'magnetic resonance imaging' with their alternatives were used. Twelve systematic reviews, 52 full texts and 28 abstracts met the preplanned study selection criteria; data from 15 articles were extracted. In patients with an elevated risk of prostate cancer who were biopsy-naive, MPMRI followed by targeted biopsy could detect 2-13% of CSPC patients whom TRUS-guided systematic biopsy missed; TRUS-guided systematic biopsy could detect 0-7% of CSPC patients whom MPMRI followed by targeted biopsy missed. In patients with an elevated risk of prostate cancer who had a previous negative TRUS-guided biopsy, MPMRI followed by targeted biopsy detected more CSPC patients than repeated TRUS-guided systematic biopsy in all four studies, with a total of 516 patients, but only one study reached a statistically significant difference. In patients with an elevated risk of prostate cancer who are biopsy-naive, there is insufficient evidence for MPMRI followed by targeted biopsy to be considered the standard of care. In patients who had a prior negative TRUS-guided systematic biopsy and show a growing risk of having CSPC, MPMRI followed by targeted biopsy may be helpful to detect more CSPC cases as opposed to a repeat TRUS-guided systematic biopsy.

Paravascular pathways contribute to vasculitis and neuroinflammation after subarachnoid hemorrhage independently of glymphatic control

Subarachnoid hemorrhage (SAH) is a devastating disease with high mortality. The mechanisms underlying its pathological complications have not been fully identified. Here, we investigate the potential involvement of the glymphatic system in the neuropathology of SAH. We demonstrate that blood components rapidly enter the paravascular space following SAH and penetrate into the perivascular parenchyma throughout the brain, causing disastrous events such as cerebral vasospasm, delayed cerebral ischemia, microcirculation dysfunction and widespread perivascular neuroinflammation. Clearance of the paravascular pathway with tissue-type plasminogen activator ameliorates the behavioral deficits and alleviates histological injury of SAH. Interestingly, AQP4^−/− mice showed no improvements in neurological deficits and neuroinflammation at day 7 after SAH compared with WT control mice. In conclusion, our study proves that the paravascular pathway dynamically mediates the pathological complications following acute SAH independently of glymphatic control.

A diagnostic kit for the enteroviruses Coxsackie A6 and A10

Recently, there has been an upward trend in the occurrence of hand-foot-mouth disease, which is correlated with Coxsackie A6 and A10 infections. Although two separate diagnostic reagents are available for these two viral strains, the protocol and diagnosis efficiency still need to be improved. More importantly, as co-infection with these viruses is common, the development of a single test kit that can diagnose both viruses would be most beneficial for clinical practice. In our study, specific primers targeting viral nucleic acids were designed and modified. Viral nucleic acids were extracted from fecal or throat swab samples by ultrasonic rupture and silicon membrane purification. The consistency, specificity, and sensitivity of the tests were further optimized by adjusting the polymerase chain reaction (PCR) conditions. The efficiency of viral nucleic acid extraction was significantly enhanced by the ultrasonic rupture and silicon membrane elution approach. Specific amplifications of both viral nucleic acids were achieved using modified primers. The optimal conditions for PCR were also determined (60°C for 30 min and 95°C for 2 min, followed by 40 cycles of denaturation for 30 s at 95°C, annealing for 30 s at 60°C, and elongation for 50 s at 72°C). Amplified products were confirmed as viral specific nucleotides by agarose gel electrophoresis and sequencing. The minimal nucleic acid concentration required for detection was 0.2 ng/L, which was adequate to yield satisfactory specificity and consistency. This novel diagnostic method has many advantages, including rapid protocols and accurate results, and can be promoted for large-scale clinical trials.

Abstract P3-13-01: Impact of routine cavity shave margins on time and money: Results from the SHAVE trial

INTRODUCTION: Taking routine cavity shave margins (CSM) reduces positive margin and re-excision rates by 50%, but the impact of this technique on operative time and overall costs have not been well-elucidated.

METHODS: The SHAVE trial randomized 235 Stage 0-3 breast cancer patients undergoing partial mastectomy 1:1 to either have further cavity shave margins resected ("shave") or not ("no shave"). Randomization occurred intraoperatively after surgeons had completed standard partial mastectomy. Intraoperative time as well as actual direct costs incurred by the hospital were measured, for both the index case as well as any surgeries over the subsequent 90 days.

RESULTS: Median patient age was 61 (range; 33-94). 54 patients (23%) had invasive cancer, 45 (19%) had DCIS, and 125 (53%) had both. Median invasive tumor size was 1.1 cm (range; 0-6.5), and median DCIS size was 1.0 cm (range; 0-9.3). The "shave" and "no shave" groups were well-matched in terms of baseline characteristics, including the proportion having a sentinel node biopsy (75.6% vs. 69.8%, p=0.32) and/or axillary node dissection (9.2% vs. 7.8%, p=0.68) at the time of the initial surgery. The median number of additional CSM in the "shave" group was 4 (range; 3-6). At the initial surgery, those in the "shave" group had a longer operative time (median 76 vs. 66 minutes, p=0.005), and higher OR, pathology and total costs (see table). 48 patients required a subsequent surgery; 45 (93.8%) for margin clearance, 3 for sentinel lymph node biopsy alone (2 in the "shave" and 1 in the "no shave" group, p=1.00). There was a significantly lower re-excision rate for margins in the "shave" group (10.9% vs. 27.6%, p=0.001). Median time to re-excision was 22 days (range; 10-62). The mean cost of additional surgeries for those who required them was no different between the "shave" and "no shave" groups ($2636 vs. $3453, p=0.12); however, given the overall lower reoperation rate in the "shave" group (12.6% vs. 28.4%, p=0.003), the mean cost per patient for additional surgeries was significantly lower in the "shave" vs. "no shave" group. Taking into account all surgeries (including the index case and any additional surgeries within 90 days), there was no significant difference in cost (from a hospital perspective) between the two groups.

Mean (± SE) Costs per patient"Shave" (n=119)"No Shave" (n=116)p-valueIndex surgery:   OR costs$1315 (± $69)$1138 (± $52)0.042Pathology costs$1195 (± $43)$795 (± $48)&lt; 0.001Total costs$4758 (± $123)$4133 (± $119)&lt; 0.001Additional surgery:   OR costs$94 (± $24)$247 (± $44)0.003Pathology costs$51 (± $18)$112 (± $21)0.031Total costs$332 (± $88)$983 (± $189)0.002Total 90 day surgery costs:   OR costs$1409 (± $76)$1385 (± $64)0.808Pathology costs$1247 (± $49)$909 (± $52)&lt; 0.001Total costs$5090 (± $166)$5116 (± $214)0.925

CONCLUSIONS: Taking routine CSM is associated with increased time and cost for the index surgery, but this is offset by the cost savings of reduced re-excision rates. While the strategies of "shave" and "no shave" are similar in terms of 90 day hospital-related costs, taking CSM is associated with a lower need for reoperative surgery, thereby reducing patient angst and improving utilization of surgeon and OR time.

Citation Format: Chagpar AB, Longley PB, Horowitz NR, Killelea BK, Tsangaris TN, Li F, Butler M, Stavris K, Yao X, Harigopal M, Bossuyt V, Lannin DR, Pusztai L, Loftus M, Davidoff AJ, Gross CP. Impact of routine cavity shave margins on time and money: Results from the SHAVE trial. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-13-01.

Myostatin deficiency partially rescues the bone phenotype of osteogenesis imperfecta model mice

Mice with osteogenesis imperfecta (+/oim), a disorder of bone fragility, were bred to mice with muscle over growth to test whether increasing muscle mass genetically would improve bone quality and strength. The results demonstrate that femora from mice carrying both mutations have greater mechanical integrity than their +/oim littermates.

INTRODUCTION

Osteogenesis imperfecta is a heritable connective tissue disorder due primarily to mutations in the type I collagen genes resulting in skeletal deformity and fragility. Currently, there is no cure, and therapeutic strategies encompass the use of antiresorptive pharmaceuticals and surgical bracing, with limited success and significant potential for adverse effects. Bone, a mechanosensing organ, can respond to high mechanical loads by increasing new bone formation and altering bone geometry to withstand increased forces. Skeletal muscle is a major source of physiological loading on bone, and bone strength is proportional to muscle mass.

METHODS

To test the hypothesis that congenic increases in muscle mass in the osteogenesis imperfecta murine model mouse (oim) will improve their compromised bone quality and strength, heterozygous (+/oim) mice were bred to mice deficient in myostatin (+/mstn), a negative regulator of muscle growth. The resulting adult offspring were evaluated for hindlimb muscle mass, and bone microarchitecture, physiochemistry, and biomechanical integrity.

RESULTS

+/oim mice deficient in myostatin (+/mstn +/oim) were generated and demonstrated that myostatin deficiency increased body weight, muscle mass, and biomechanical strength in +/mstn +/oim mice as compared to +/oim mice. Additionally, myostatin deficiency altered the physiochemical properties of the +/oim bone but did not alter bone remodeling.

CONCLUSIONS

Myostatin deficiency partially improved the reduced femoral bone biomechanical strength of adult +/oim mice by increasing muscle mass with concomitant improvements in bone microarchitecture and physiochemical properties.

Nitric Oxide-cGMP-PKG Pathway Acts on Orai1 to Inhibit the Hypertrophy of Human Embryonic Stem Cell-Derived Cardiomyocytes

Cardiac hypertrophy is an abnormal enlargement of heart muscle. It frequently results in congestive heart failure, which is a leading cause of human death. Previous studies demonstrated that the nitric oxide (NO), cyclic GMP (cGMP), and protein kinase G (PKG) signaling pathway can inhibit cardiac hypertrophy and thus improve cardiac function. However, the underlying mechanisms are not fully understood. Here, based on the human embryonic stem cell-derived cardiomyocyte (hESC-CM) model system, we showed that Orai1, the pore-forming subunit of store-operated Ca(2+) entry (SOCE), is the downstream effector of PKG. Treatment of hESC-CMs with an α-adrenoceptor agonist phenylephrine (PE) caused a marked hypertrophy, which was accompanied by an upregulation of Orai1. Moreover, suppression of Orai1 expression/activity using Orai1-siRNAs or a dominant-negative construct Orai1(G98A) inhibited the hypertrophy, suggesting that Orai1-mediated SOCE is indispensable for the PE-induced hypertrophy of hESC-CMs. In addition, the hypertrophy was inhibited by NO and cGMP via activating PKG. Importantly, substitution of Ala for Ser(34) in Orai1 abolished the antihypertrophic effects of NO, cGMP, and PKG. Furthermore, PKG could directly phosphorylate Orai1 at Ser(34) and thus prevent Orai1-mediated SOCE. Together, we conclude that NO, cGMP, and PKG inhibit the hypertrophy of hESC-CMs via PKG-mediated phosphorylation on Orai1-Ser-34. These results provide novel mechanistic insights into the action of cGMP-PKG-related antihypertrophic agents, such as NO donors and sildenafil.

Different components of chicken ovalbumin extract promote different cell proliferation

The chicken ovalbumin extracts could promote cell survival and proliferation. In the present study, the different components in chicken ovalbumin extracts were further separated to find the component primarily responsible for promoting cell proliferation. Components of differing molecular weight were separated from chicken ovalbumin extracts by ultrafiltration. Different components were co&mdash;cultured with different cells at different final concentrations, and the effects on cell proliferation were subsequently determined by a CellTiter 96 Aqueous One Solution Cell Proliferation Assay kit (Promega). Components from chicken ovalbumin extracts less than 3 kD in size can promote 293T cell and 293T&mdash;GFP cell proliferation. The components from chicken ovalbumin extract more than 3 kD in size can promote bone marrow or umbilical cord mesenchymal stem cell (MSC) proliferation. The separation of components from chicken ovalbumin less than and more than 3 kD in size that are able to function as active components for the promotion of different cellular proliferation. This discovery may identify a new and convenient additive for cell culture media, promoting cell growth and proliferation.

Photonic crystal cavity-assisted upconversion infrared photodetector

We describe an upconversion infrared photodetector assisted by a gallium phosphide photonic crystal nanocavity directly coupled to a silicon photodiode. The strongly cavity-enhanced second harmonic signal radiating from the gallium phosphide membrane can thus be efficiently collected by the silicon photodiode, which promises a high photoresponsivity of the upconversion detector as 0.81 A/W with the coupled power of 1W. The integrated upconversion photodetector also functions as a compact autocorrelator with sub-ps resolution for measuring pulse width and chirp.

Deficiency of PdxR in Streptococcus mutans affects vitamin B6 metabolism, acid tolerance response and biofilm formation

Streptococcus mutans, a key etiological agent of the human dental caries, lives primarily on the tooth surface in tenacious biofilms. The SMU864 locus, designated pdxR, is predicted to encode a member of the novel MocR/GabR family proteins, which are featured with a winged helix DNA-binding N-terminal domain and a C-terminal domain highly homologous to the pyridoxal phosphate-dependent aspartate aminotransferases. A pdxR-deficient mutant, TW296, was constructed using allelic exchange. PdxR deficiency in S. mutans had little effect on cell morphology and growth when grown in brain heart infusion. However, when compared with its parent strain, UA159, the PdxR-deficient mutant displayed major defects in acid tolerance response and formed significantly fewer biofilms (P < 0.01). When analyzed by real-time polymerase chain reaction, PdxR deficiency was found to drastically reduce expression of an apparent operon encoding a pyridoxal kinase (SMU865) and a pyridoxal permease (SMU866) of the salvage pathway of vitamin B6 biosynthesis. In addition, PdxR deficiency also altered the expression of genes for ClpL protease, glucosyltransferase B and adhesin SpaP, which are known to play important roles in stress tolerance and biofilm formation. Consistently, PdxR-deficiency affected the growth of the deficient mutant when grown in defined medium with and without vitamin B6 . Further studies revealed that although S. mutans is known to require vitamin B6 to grow in defined medium, B6 vitamers, especially pyridoxal, were strongly inhibitory at millimolar concentrations, against S. mutans growth and biofilm formation. Our results suggest that PdxR in S. mutans plays an important role in regulation of vitamin B6 metabolism, acid tolerance response and biofilm formation.

Protein conformation by EPR spectroscopy using gadolinium tags clicked to genetically encoded p-azido-l-phenylalanine

First example of gadolinium tags attached to a pair of unnatural amino acids for distance measurements by double electron–electron resonance.

Expression profile of Nanos2 gene in dairy goat and its inhibitory effect on Stra8 during meiosis

OBJECTIVES

Nanos2, an RNA-binding protein, belongs to the Nanos gene-coding family and contains two CCHC zinc-finger motifs. In mouse, it plays a pivotal role in male germ cell development, and self-renewal of spermatogonial stem cells. However, little is known of its expression pattern and functions in dairy goat testis.

MATERIALS AND METHODS

Immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were used to generate the expression profile of Nanos2 in dairy goat testis. Furthermore, its overexpression effects on male germline stem cells (mGSCs) were studied using qRT-PCR, immunofluorescence, dual-luciferase reporter assay and western blotting.

RESULTS

Nanos2 is a conservative gene expressed widely in various tissues, especially in pancreas, and it displays higher expression in adult testes than in other age groups. Overexpression of Nanos2 significantly downregulated meiosis-related genes, including Stra8 and Scp3, which induced inhibition of meiosis. Results from dual-luciferase reporter assay and western blotting indicated that Nanos2 directly downregulated Stra8 in goat GmGSCs.

CONCLUSIONS

Taken together, these results suggest that Nanos2 plays an important role in spermatogonia and that its overexpression restrained meiosis in the dairy goat.