Abrogation of Cbl–PI3K Interaction Increases Bone Formation and Osteoblast Proliferation

Cbl is an adaptor protein and E3 ligase that plays both positive and negative roles in several signaling pathways that affect various cellular functions. Tyrosine 737 is unique to Cbl and phosphorylated by Src family kinases. Phosphorylated CblY737 creates a binding site for the p85 regulatory subunit of phosphatidylinositol 3 kinase (PI3K) that also plays an important role in the regulation of bone homeostasis. To investigate the role of Cbl–PI3K interaction in bone homeostasis, we examined knock-in mice in which the PI3K binding site on Cbl was ablated due to the substitution of tyrosine 737 to phenylalanine (CblYF/YF, YF mice). We previously reported that bone volume in these mice is increased due to decreased osteoclast function (Adapala et al., J Biol Chem 285:36745–36758, 19). Here, we report that YF mice also have increased bone formation and osteoblast numbers. In ex vivo cultures bone marrow-derived YF osteoblasts showed increased Col1A expression and their proliferation was also significantly augmented. Moreover, proliferation of MC3T3-E1 cells was increased after treatment with conditioned medium generated by culturing YF bone marrow stromal cells. Expression of stromal derived factor-1 (SDF-1) was increased in YF bone marrow stromal cells compared to wild type. Increased immunostaining of SDF-1 and CXCR4 was observed in YF bone marrow stromal cells compared to wild type. Treatment of YF condition medium with neutralizing anti-SDF-1 and anti-CXCR4 antibodies attenuated MC3T3-E1 cell proliferation. Cumulatively, these results show that abrogation of Cbl–PI3K interaction perturbs bone homeostasis, affecting both osteoclast function and osteoblast proliferation

Identification of new sources of resistance to dry root rot caused by Macrophomina phaseolina isolates from India and Myanmar in a mungbean mini-core collection

Dry root rot (DRR), caused by Macrophomina phaseolina, is a prevalent disease of mungbean in Myanmar, and an emerging problem in South Asia. The pathogen is a polyphagous necrotroph, survives in the soil for many years that results disease mitigation difficult. Managing DRR in mungbean through an integrated approach has been suggested, and the use of resistant varieties is one of the economical methods. The present study aimed to identify sources of resistance against DRR from a mungbean mini-core collection and to characterize the associated M. phaseolina isolates from India and Myanmar. Evaluation of the 296 mungbean mini-core accessions against the isolate MP1 by paper towel method identified 29 accessions with DRR resistance (disease scores: ≤ 3), and 18 of them with the consistent resistance in the repeated experiment. During the screening of 18 resistant accessions in the glasshouse, nine accessions were found DRR resistance in repeated sick pot experiments with ≤10% disease incidence. A subset of 30 accessions was selected from the mini-core collection based on their in vitro DRR reactions. These accessions were evaluated for DRR resistance in the field in Yezin, Myanmar in 2018 and 2019. Out of the 30 accessions, ten accessions were found DRR resistance with ≤10% disease incidence in both years of evaluations. Pooled analysis of percent disease incidence data of 15 accessions common in both glasshouse and field revealed the stability of accessions VI001509AG, VI001244AG, and VI001400AG for DRR resistance across years and locations. The three resistant accessions along with a susceptible check VC693088 were re-evaluated by paper towel method against nine additional M. phaseolina isolates from India (MP3-MP11). The accessions VI001509AG and VI001400AG were resistant to all nine isolates, while accession VI001244AG was resistant to MP5, MP6, and MP7 isolates. These accessions could be used in mungbean DRR resistance breeding programs

Genetic Variation for Nitrogen Use Efficiency Traits in Global Diversity Panel and Parents of Mapping Populations in Pearl Millet

Nitrogen (N) is one of the primary macronutrients required for crop growth and yield. This nutrient is especially limiting in the dry and low fertility soils where pearl millet [Pennisetum glaucum (L.) R. Br] is typically grown. Globally, pearl millet is the sixth most important cereal grown by subsistence farmers in the arid and semi-arid regions of sub-Saharan Africa and the Indian subcontinent. Most of these agro-ecologies have low N in the root zone soil strata. Therefore, there is an immense need to identify lines that use nitrogen efficiently. A set of 380 diverse pearl millet lines consisting of a global diversity panel (345), parents of mapping populations (20), and standard checks (15) were evaluated in an alpha-lattice design with two replications, 25 blocks, a three-row plot for 11 nitrogen use efficiency (NUE) related traits across three growing seasons (Summer 2017, Rainy 2017, and Summer 2018) in an N-depleted precision field under three different N levels (0%-N0, 50%-N50, 100%-N100 of recommended N, i.e., 100 kg h

Absence of Type VI Collagen Paradoxically Improves Cardiac Function, Structure, and Remodeling After Myocardial Infarction

RATIONALE: We previously reported that type VI collagen deposition increases in the infarcted myocardium in vivo. To date, a specific role for this nonfibrillar collagen has not been explored in the setting of myocardial infarction (MI). OBJECTIVE: To determine whether deletion of type VI collagen in an in vivo model of post-MI wound healing would alter cardiac function and remodeling in the days to weeks after injury. METHODS AND RESULTS: Wild-type and Col6a1(-/-) mice were subjected to MI, followed by serial echocardiographic and histological assessments. At 8 weeks after MI, infarct size was significantly reduced, ejection fraction was significantly preserved (43.9% \ub1 3.3% versus 29.1% \ub1 4.3% for wild-type), and left ventricular chamber dilation was attenuated in the Col6a1(-/-) MI group (25.8% \ub1 7.9% increase versus 62.6% \ub1 16.5% for wild-type). The improvement in cardiac remodeling was evident as early as 10 days after MI in the Col6a1(-/-) mice. Myocyte apoptosis within the infarcted zones was initially greater in the Col6a1(-/-) group 3 days after MI, but by day 14 this was significantly reduced. Collagen deposition also was reduced in the infarcted and remote areas of the Col6a1(-/-) hearts. The reductions in chronic myocyte apoptosis and fibrosis are critical events leading to improved long-term remodeling and functional outcomes. CONCLUSIONS: These unexpected results demonstrate for the first time that deletion of type VI collagen in this knockout model plays a critical protective role after MI by limiting infarct size, chronic apoptosis, aberrant remodeling, and fibrosis, leading to preservation of cardiac function

Function and fate of myofibroblasts after myocardial infarction.

The importance of cardiac fibroblasts in the regulation of myocardial remodelling following myocardial infarction (MI) is becoming increasingly recognised. Studies over the last few decades have reinforced the concept that cardiac fibroblasts are much more than simple homeostatic regulators of extracellular matrix turnover, but are integrally involved in all aspects of the repair and remodelling of the heart that occurs following MI. The plasticity of fibroblasts is due in part to their ability to undergo differentiation into myofibroblasts. Myofibroblasts are specialised cells that possess a more contractile and synthetic phenotype than fibroblasts, enabling them to effectively repair and remodel the cardiac interstitium to manage the local devastation caused by MI. However, in addition to their key role in cardiac restoration and healing, persistence of myofibroblast activation can drive pathological fibrosis, resulting in arrhythmias, myocardial stiffness and progression to heart failure. The aim of this review is to give an appreciation of both the beneficial and detrimental roles of the myofibroblast in the remodelling heart, to describe some of the major regulatory mechanisms controlling myofibroblast differentiation including recent advances in the microRNA field, and to consider how this cell type could be exploited therapeutically