Csk differentially regulates Src64 during distinct morphological events in Drosophila germ cells

The Src family protein tyrosine kinases (SFKs) are crucial regulators of cellular morphology. In Drosophila, Src64 controls complex morphological events that occur during oogenesis. Recent studies have identified key Src64-dependent mechanisms that regulate actin cytoskeletal dynamics during the growth of actin-rich ring canals, which act as intercellular bridges between germ cells. By contrast, the molecular mechanisms that regulate Src64 activity levels and potential roles for Src64 in additional morphological events in the ovary have not been defined. In this report, we demonstrate that regulation of Src64 by Drosophila C-terminal-Src Kinase (Csk) contributes to the packaging of germline cysts by overlying somatic follicle cells during egg chamber formation. These results uncover novel roles for both Csk and Src64 in a dynamic event that involves adhesion, communication between cell types and control of cell motility. Strikingly, Src64 and Csk function in the germline to control packaging, not in migrating follicle cells, suggesting novel functions for this signaling cassette in regulating dynamic adhesion. In contrast to the role played by Csk in the regulation of Src64 activity during packaging, Csk is dispensable for ring canal growth control, indicating that distinct mechanisms control Src64 activity during different morphological events.     

A delicate interplay of structure, dynamics, and thermodynamics for function: a high pressure NMR study of outer surface protein A

Outer surface protein A (OspA) is a crucial protein in the infection of Borrelia burgdorferi causing Lyme disease. We studied conformational fluctuations of OspA with high-pressure ¹⁵N/¹H two-dimensional NMR along with high-pressure fluorescence spectroscopy. We found evidence within folded, native OspA for rapid local fluctuations of the polypeptide backbone in the nonglobular single layer β-sheet connecting the N- and C-terminal domains with τ << ms, which may give the two domains certain independence in mobility and thermodynamic stability. Furthermore, we found that folded, native OspA is in equilibrium (τ >> ms) with a minor conformer I, which is almost fully disordered and hydrated for the entire C-terminal part of the polypeptide chain from β8 to the C-terminus. Conformer I is characterized with ΔG⁰ = 32 ± 9 kJ/mol and ΔV⁰ = −140 ± 40 mL/mol, populating only ∼0.001% at 40°C at 0.1 MPa, pH 5.9. Because in the folded conformer the receptor binding epitope of OspA is buried in the C-terminal domain, its transition into conformer I under in vivo conditions may be critical for the infection of B. burgdorferi. The formation and stability of the peculiar conformer I are apparently supported by a large packing defect or cavity located in the C-terminal domain.     

On the shoulders of giants: a historical perspective of unique experimental methods in mammary gland research

While most organs undergo development in utero, the mouse mammary gland orchestrates five major developmental stages following birth: pre-puberty, puberty, pregnancy, lactation, and involution. Induced by both local and systemic factors, these five developmental stages transpire with dramatic alterations in glandular morphology and cellular function. As an experimental system, the mammary gland provides remarkable accessibility to processes regulating stem cell function, hormone response, and epithelial-stromal-extracellular matrix interactions. This review will provide a historical perspective of the unique in vitro and in vivo techniques used to study the mammary gland and how these methods have provided valuable insight into the biology of this organ.     

IRE1α induces thioredoxin-interacting protein to activate the NLRP3 inflammasome and promote programmed cell death under irremediable ER stress

When unfolded proteins accumulate to irremediably high levels within the endoplasmic reticulum (ER), intracellular signaling pathways called the unfolded protein response (UPR) become hyperactivated to?cause programmed cell death. We discovered that?thioredoxin-interacting protein (TXNIP) is?a critical node in this "terminal UPR." TXNIP becomes rapidly induced by IRE1α, an ER bifunctional kinase/endoribonuclease (RNase). Hyperactivated IRE1α increases TXNIP mRNA stability by reducing levels of a TXNIP destabilizing microRNA, miR-17. In turn, elevated TXNIP protein activates the NLRP3 inflammasome, causing procaspase-1 cleavage and interleukin 1β (IL-1β) secretion. Txnip gene deletion reduces pancreatic β cell death during ER stress and suppresses diabetes caused by proinsulin misfolding in the Akita mouse. Finally, small molecule?IRE1α RNase inhibitors suppress TXNIP production to block IL-1β secretion. In summary, the IRE1α-TXNIP pathway is used in the terminal UPR to promote sterile inflammation and programmed cell death and may be targeted to develop effective treatments for cell degenerative diseases.     

Perturbed desmosomal cadherin expression in grainy head-like 1-null mice

In Drosophila, the grainy head (grh) gene plays a range of key developmental roles through the regulation of members of the cadherin gene family. We now report that mice lacking the grh homologue grainy head-like 1 (Grhl1) exhibit hair and skin phenotypes consistent with a reduction in expression of the genes encoding the desmosomal cadherin, desmoglein 1 (Dsg1). Grhl1-null mice show an initial delay in coat growth, and older mice exhibit hair loss as a result of poor anchoring of the hair shaft in the follicle. The mice also develop palmoplantar keratoderma, analogous to humans with DSG1 mutations. Sequence analysis, DNA binding, and chromatin immunoprecipitation experiments demonstrate that the human and mouse Dsg1 promoters are direct targets of GRHL1. Ultrastructural analysis reveals reduced numbers of abnormal desmosomes in the interfollicular epidermis. These findings establish GRHL1 as an important regulator of the Dsg1 genes in the context of hair anchorage and epidermal differentiation, and suggest that cadherin family genes are key targets of the grainy head-like genes across 700 million years of evolution.     

The prevalence of obesity in ethnic admixture adults

Objective: To determine whether the prevalence of obesity in ethnic admixture adults varies systematically from the average of the prevalence estimates for the ethnic groups with whom they share a common ethnicity. Methods and Procedures: The sample included 215,000 adults who reported one or more ethnicities, height, weight, and other characteristics through a mailed survey. Results: The highest age‐adjusted prevalence of overweight (BMI ≥ 25) was in Hawaiian/Latino men (88%; n = 41) and black/Latina women (74.5%; n = 79), and highest obesity (BMI ≥ 30) rates were in Hawaiian/Latino men (53.7%; n = 41) and Hawaiian women (39.2%, n = 1,247). The prevalence estimates for most admixed groups were similar to or higher than the average of the prevalences for the ethnic groups with whom they shared common ethnicities. For instance, the prevalence of overweight/obesity in five ethnic admixtures—Asian/white, Hawaiian/white, Hawaiian/Asian, Latina/white, and Hawaiian/Asian/white ethnic admixtures—was significantly higher (P < 0.0001) than the average of the prevalence estimates for their component ethnic groups. Discussion: The identification of individuals who have a high‐risk ethnic admixture is important not only to the personal health and well‐being of such individuals, but could also be important to future efforts in order to control the epidemic of obesity in the United States.     

Copper-induced structural changes in the ovine prion protein are influenced by a polymorphism at codon 112

Prion diseases are associated with conformational change in the copper-binding protein PrP. The copper-binding sites in PrP are located in the N-terminal region of the molecule and comprise a series of tandem repeats of the sequence PHGGGWGQ together with two histidines at residues 96 and 111 (human PrP numbering). The co-ordination of copper ions within the non-octapeptide repeat metal ion-binding site involves Met109 (human numbering, which corresponds with Met112 in ovine PrP) and the binding of copper to this site leads to an increase in beta-sheet formation in PrP. Here we have investigated the influence of the M112T polymorphism on copper-induced structural changes in ovine recombinant PrP. M112ARQ and T112ARQ ovine PrP show similar secondary structure although M112ARQ appears more thermostable than T112ARQ. Following treatment with copper, M112ARQ showed a greater increase in beta-sheet content than did T112ARQ when measured by CD spectroscopy and by ELISA using anti-PrP monoclonal antibodies. These biochemical and biophysical differences between M112ARQ and T112ARQ correlate with similar differences seen between allelic variants of ovine PrP associated with susceptibility and resistance to classical scrapie. These observations suggest that T112ARQ may provide a measure of resistance to classical scrapie pathogenesis compared to M112ARQ.     

Detection of immune complexes and evaluation of alcoholic individuals' serological profile in the diagnosis of strongyloidiasis

Strongyloidiasis is a human parasitosis that is considered a public health problem. Early diagnosis of this infection is extremely important in immunocompromised patients (i.e. subjects with alcoholism). This study aimed to evaluate anti-Strongyloides immunoglobulin G (IgG) and immunoglobulin A (IgA), assess levels of circulating immune complexes (IC) and determine IgG avidity in serum samples from alcoholic and nonalcoholic individuals. A total of 140 blood samples were collected from male individuals (70 alcoholic and 70 nonalcoholic subjects). Serum was obtained and analysed by enzyme-linked immunosorbent assay for IgG, IgA, IC detection and avidity determination. Anti-Strongyloides IgG was detected in 55.7% of alcoholic subjects and 32.8% nonalcoholics, while IC levels showed frequencies of 38.6% and 17.1% in these groups, respectively. Anti-Strongyloides IgA was lower among alcoholics (4.3%) than nonalcoholics (34.3%). Spearman's correlation coefficient reported a positive correlation between IgG, IC and IgA in alcoholic individuals and no correlation in nonalcoholics. The median avidity index was higher in alcoholics (83.8%) than nonalcoholic subjects (73.2%). In conclusion, this study shows that alcoholic subjects produced specific antibodies against S. stercoralis regardless of the possible immunosuppression caused by chronic alcoholism. Considering that alcoholics are more susceptible to the severe forms of strongyloidiasis, the implementation of immunological methods as a complementary approach to parasitological diagnostics (i.e. detection of IgG, IC and antibody avidity) appears to be an alternative method for early diagnosis in these individuals.