Differential role of PI-3Kinase p85 ([alpha] & [beta] regulatory subunits in mast cell development

Indiana University-Purdue University Indianapolis (IUPUI)Stem cell factor (SCF) mediated c-Kit signaling, and downstream activation of Phosphatidylinositol-3 Kinase (PI-3K) is critical for multiple biological effects mediated by mast cells. Mast cells express multiple regulatory subunits of PI-3Kinase, including p85α, p85β, p50α and p55α. In the present study, we have examined the relationship between p85α and p85β subunit in mast cell development and show that loss of p85α in mast cell progenitors impairs their growth, maturation and survival whereas loss of p85β enhances this process. To further delineate the mechanism (s) by which p85α provides specificity to mast cell biology, we compared the amino acid sequences between p85α and p85β subunits. The two isoforms share significant structural homology in the two SH2 domains, but show significant differences in the N-terminal SH3 domain as well as the BCR homology domain. To determine whether the c-Kit induced reduction in growth of mast cells is contributed via the N-terminal SH3 or the BCR homology domain, we cloned and expressed the shorter splice variant p50α, and various truncated mutant versions of p85α in p85α deficient mast cells. We demonstrate both invitro and invivo that while the SH3 and the BH domains of p85 are dispensable for mast cell maturation; they are essential for normal growth and survival. In contrary to existing dogma on redundant functional role of PI-3K regulatory subunits, this study proves that p85α and p85β regulatory subunits of PI-3K have unique roles in mast cell development. We prove that p85α deficiency impairs the expression of multiple growth, survival and maturation related genes whereas p85β deficiency inhibits c-Kit receptor internalization and degradation. This novel finding on negative role of p85β in mast cell development has significant clinical implication, as this knowledge could be used to develop treatments for mast-cell-associated leukemia and mastocytosis

Class IA PI3Kinase Regulatory Subunit, p85α, Mediates Mast Cell Development through Regulation of Growth and Survival Related Genes

Stem cell factor (SCF) mediated KIT receptor activation plays a pivotal role in mast cell growth, maturation and survival. However, the signaling events downstream from KIT are poorly understood. Mast cells express multiple regulatory subunits of class 1A PI3Kinase (PI3K) including p85α, p85β, p50α, and p55α. While it is known that PI3K plays an essential role in mast cells; the precise mechanism by which these regulatory subunits impact specific mast cell functions including growth, survival and cycling are not known. We show that loss of p85α impairs the growth, survival and cycling of mast cell progenitors (MCp). To delineate the molecular mechanism (s) by which p85α regulates mast cell growth, survival and cycling, we performed microarray analyses to compare the gene expression profile of MCps derived from WT and p85α-deficient mice in response to SCF stimulation. We identified 151 unique genes exhibiting altered expression in p85α-deficient cells in response to SCF stimulation compared to WT cells. Functional categorization based on DAVID bioinformatics tool and Ingenuity Pathway Analysis (IPA) software relates the altered genes due to lack of p85α to transcription, cell cycle, cell survival, cell adhesion, cell differentiation, and signal transduction. Our results suggest that p85α is involved in mast cell development through regulation of expression of growth, survival and cell cycle related genes

Genomics of Osteoporosis

Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree Master of Sciences in the School of Informatics, Indiana University, August 2004Osteoporosis is the most common bone disease in United States and developed countries and a major public health threat for an estimated 44 million Americans. It is characterized by low bone mineral density and micro architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture, especially of hip, spine and wrist. Osteoporosis is multifactorial disease influenced by large number of environmental and genetic factors. Though a number of FDA approved drugs are available for treating this complex disease, a medication, which could specifically and effectively reverse symptoms of it is lackin. As the initial step for approaching disease treatment my current research focuses on locatin candidate genes on linkage regions for BMD on human chromosomes, which potentially can be used for developing novel targets and strategies for therapeutic interventions. We will also define the mouse homologs in the syntenic regions as basis for future studies involving animal models of disturbed BMD. An automated interface which will give information on human - mouse synteny between human marker intervals of interest was developed which will expedite future synteny studies

An accurate aging clock developed from large-scale gut microbiome and human gene expression data

Summary: Accurate measurement of the biological markers of the aging process could provide an “aging clock” measuring predicted longevity and enable the quantification of the effects of specific lifestyle choices on healthy aging. Using machine learning techniques, we demonstrate that chronological age can be predicted accurately from (1) the expression level of human genes in capillary blood and (2) the expression level of microbial genes in stool samples. The latter uses a very large metatranscriptomic dataset, stool samples from 90,303 individuals, which arguably results in a higher quality microbiome-aging model than prior work. Our analysis suggests associations between biological age and lifestyle/health factors, e.g., people on a paleo diet or with IBS tend to have higher model-predicted ages and people on a vegetarian diet tend to have lower model-predicted ages. We delineate the key pathways of systems-level biological decline based on the age-specific features of our model

Not Available

Not AvailableSmallholder farmers, majorly constituted in rainfed regions account for a sizeable proportion of the agricultural community. Various constraints like fragile ecosystems, increasing competition for land and water, lack of infrastructure, low investment capacity, low-risk bearing capacity, poor market linkages, price volatility, etc. limit enhancing productivity levels in the areas congregated by small farmers which ultimately restricts livelihood enhancement. The adoption of Indigenous Technical Knowledge (ITK) can be regarded as a viable option towards enhancing agronomic productivity and elevating livelihood status. The current review majorly throws light on various indigenous practices catering to meet various objectives viz. climate change adaptation, soil health enhancement, moisture conservation, seed storage, plant protection, etc. and steps involved in ITK analysisNot Availabl

The p85α Subunit of Class IA Phosphatidylinositol 3-Kinase Regulates the Expression of Multiple Genes Involved in Osteoclast Maturation and Migration▿

Intracellular signals involved in the maturation and function of osteoclasts are poorly understood. Here, we demonstrate that osteoclasts express multiple regulatory subunits of class IA phosphatidylinositol 3-kinase (PI3-K) although the expression of the full-length form of p85α is most abundant. In vivo, deficiency of p85α results in a significantly greater number of trabeculae and significantly lower spacing between trabeculae as well as increased bone mass in both males and females compared to their sex-matched wild-type controls. Consistently, p85α−/− osteoclast progenitors show impaired growth and differentiation, which is associated with reduced activation of Akt and mitogen-activated protein kinase extracellular signal-regulated kinase 1 (Erk1)/Erk2 in vitro. Furthermore, a significant reduction in the ability of p85α−/− osteoclasts to adhere to as well as to migrate via integrin αvβ3 was observed, which was associated with reduced bone resorption. Microarray as well as quantitative real-time PCR analysis of p85α−/− osteoclasts revealed a significant reduction in the expression of several genes associated with the maturation and migration of osteoclasts, including microphathalmia-associated transcription factor, tartrate-resistant acid phosphatase, cathepsin K, and β3 integrin. Restoring the expression of the full-length form of p85α but not the version with a deletion of the Src homology-3 domain restored the maturation of p85α−/− osteoclasts to wild-type levels. These results highlight the importance of the full-length version of the p85α subunit of class IA PI3-K in controlling multiple aspects of osteoclast functions

Reduced cycling of p85α-deficient BMMCs.

<p>BMMCs from WT and <i>p85α−/−</i> mice were starved for 6 hours in serum- and cytokine-free media and cultured in the presence or absence of SCF (50 ng/mL). After 48 hours, cells were stained with propidium iodide followed by flow cytometry analysis as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0028979#s4" target="_blank">methods</a>. Shown is a representative histogram (Left panel) and bar graph (Right panel) demonstrating the percentage of cells in S phase in the presence or absence of SCF. Similar results were observed in two independent experiments. *p<0.05, WT vs. <i>p85α−/−</i>.</p

Ingenuity Pathway Analysis (IPA) of cell survival related genes in <i>p85α−/−</i> MCp's in response to SCF stimulation.

<p>Altered genes in <i>p85α^−/−</i> cells after SCF stimulation were analyzed by IPA software to analyze their closely associated gene network. Significantly altered cell survival related genes in <i>p85α−/−</i> MCp's in response to SCF stimulation were indicated.</p