Change in cell shape is required for matrix metalloproteinase-induced epithelial-mesenchymal transition of mammary epithelial cells

Cell morphology dictates response to a wide variety of stimuli, controlling cell metabolism, differentiation, proliferation, and death. Epithelial-mesenchymal transition (EMT) is a developmental process in which epithelial cells acquire migratory characteristics, and in the process convert from a "cuboidal" epithelial structure into an elongated mesenchymal shape. We had shown previously that matrix metalloproteinase-3 (MMP3) can stimulate EMT of cultured mouse mammary epithelial cells through a process that involves increased expression of Rac1b, a protein that stimulates alterations in cytoskeletal structure. We show here that cells treated with MMP-3 or induced to express Rac1b spread to cover a larger surface, and that this induction of cell spreading is a requirement of MMP-3/Rac1b-induced EMT. We find that limiting cell spreading, either by increasing cell density or by culturing cells on precisely defined micropatterned substrata, blocks expression of characteristic markers of EMT in cells treated with MMP-3. These effects are not caused by general disruptions in cell signaling pathways, as TGF-beta-induced EMT is not affected by similar limitations on cell spreading. Our data reveal a previously unanticipated cell shape-dependent mechanism that controls this key phenotypic alteration and provide insight into the distinct mechanisms activated by different EMT-inducing agents.     

Moonlighting is mainstream: paradigm adjustment required

Moonlighting--the performance of more than one function by a single protein--is becoming recognized as a common phenomenon with important implications for systems biology and human health. The different functions of a moonlighting protein may use different regions of the protein structure, or alternative structures that occur due to post-translational modifications and/or differences in binding partners. Often the different functions of moonlighting proteins are used at different times or in different places. The existence of moonlighting functions complicates efforts to understand metabolic and regulatory networks, as well as physiological and pathological processes in organisms. Because moonlighting functions can play important roles in disease processes, an improved understanding of moonlighting proteins will provide new opportunities for pharmacological manipulations that specifically target a function involved in pathology while sparing physiologically important functions.     

The ubiquitin pathway is required for innate immunity in Arabidopsis

Plant defences require a multitude of tightly regulated resistance responses. In Arabidopsis, the unique gain-of-function mutant suppressor of npr1-1 constitutive 1 ( snc1 ) carries a point mutation in a Resistance ( R )-gene, resulting in constitutive activation of defence responses without interaction with pathogens. This has allowed us to identify various downstream signalling components essential in multiple defence pathways. One mutant that suppresses snc1 -mediated constitutive resistance is modifier of snc1 5 ( mos5 ), which carries a 15-bp deletion in UBA1 , one of two ubiquitin-activating enzyme genes in Arabidopsis. A mutation in UBA2 does not suppress snc1 , suggesting that these two genes are not equally required in Arabidopsis disease resistance. On the other hand, a mos5 uba2 double mutant is lethal, implying partial redundancy of the two homologues. Apart from affecting snc1 -mediated resistance, mos5 also exhibits enhanced disease susceptibility to a virulent pathogen and is impaired in response to infection with avirulent bacteria carrying the protease elicitor AvrRpt2. The mos5 mutation in the C-terminus of UBA1 might affect binding affinity of the downstream ubiquitin-conjugating enzymes, thus perturbing ubiquitination of target proteins. Furthermore, SGT1b and RAR1, which are necessary for resistance conferred by the SNC1 -related R -genes RPP4 and RPP5 , are dispensable in snc1 -mediated resistance. Our data reveal the definite requirement for the ubiquitination pathway in the activation and downstream signalling of several R-proteins.     

The cyclophilin homolog ninaA is required in the secretory pathway

In Drosophila, the major rhodopsin Rh1 is synthesized in endoplasmic reticulum (ER)-bound ribosomes of the R1-R6 photoreceptor cells and is then transported to the rhabdomeres where it functions in phototransduction. Mutations in the cyclophilin homolog ninaA lead to a 90% reduction in Rh1 opsin. Cyclophilins have been shown to be peptidyl-prolyl cis-trans isomerases and have been implicated in catalyzing protein folding. We now show that mutations in the ninaA gene severely inhibit opsin transport from the ER, leading to dramatic accumulations of ER cisternae in the photoreceptor cells. These results demonstrate that ninaA functions in the ER. Interestingly, ninaA and Rh1 also colocalize to secretory vesicles, suggesting that Rh1 may require ninaA as it travels through the distal compartments of the secretory pathway. These results are discussed in relation to the possible role of cyclophilins in protein folding and intracellular protein trafficking.     

The MutL ATPase is required for mismatch repair

Members of the MutL family contain a novel nucleotide binding motif near their amino terminus, and the Escherichia coli protein has been found to be a weak ATPase (Ban, C., and Yang, W. (1998) Cell 95, 541-552). Genetic analysis has indicated that substitution of Lys for Glu-32 within this motif of bacterial MutL results in a strong dominant negative phenotype (Aronshtam, A., and Marinus, M. G. (1996) Nucleic Acids Res. 24, 2498-2504). By in vitro comparison of MutL-E32K with the wild type protein, we show the mutant protein to be defective in DNA-activated ATP hydrolysis, as well as MutS- and MutL-dependent activation of the MutH d(GATC) endonuclease and the mismatch repair excision system. MutL-E32K also acts in dominant negative manner in the presence of wild type MutL in vitro, inhibiting the overall mismatch repair reaction, as well as MutH activation. As judged by protein affinity chromatography, MutL and MutL-E32K both support formation of ternary complexes that also contain MutS and MutH or MutS and DNA helicase II. These findings imply that the MutL nucleotide binding center is required for mismatch repair and suggest that the dominant negative behavior of the MutL-E32K mutation is due to the formation of dead-end complexes in which the MutL-E32K protein is unable to transduce a signal from MutS that otherwise results in mismatch-dependent activation of the MutH d(GATC) endonuclease or the unwinding activity of helicase II.     

Plant cell division: ROS homeostasis is required

Accumulated evidence indicates that ROS fluctuations play a critical role in cell division. Dividing plant cells rapidly respond to them. Experimental disturbance of ROS homeostasis affects: tubulin polymerization; PPB, mitotic spindle and phragmoplast assembly; nuclear envelope dynamics; chromosome separation and movement; cell plate formation. Dividing cells mainly accumulate at prophase and delay in passing through the successive cell division stages. Notably, many dividing root cells of the rhd2 Arabidopsis thaliana mutants, lacking the RHD2/AtRBOHC protein function, displayed aberrations, comparable to those induced by low ROS levels. Some protein molecules, playing key roles in signal transduction networks inducing ROS production, participate in cell division. NADPH oxidases and their regulators PLD, PI3K and ROP-GTPases, are involved in MT polymerization and organization. Cellular ROS oscillations function as messages rapidly transmitted through MAPK pathways inducing MAP activation, thus affecting MT dynamics and organization. RNS implication in cell division is also considered.     

The Lean Woman

Objective: In the current obesity epidemic, the ability to remain lean is beginning to be uncommon. Therefore, it was considered of interest to characterize such subjects. Research Methods and Procedures: From a population of premenopausal women (n = 270), all 40 years of age, those with a similar body mass index (BMI) as women at the age of 21 years, born the same year (BMI = 21.1 kg/m²) were selected among nonsmokers and compared with the remaining nonsmoking women. Results: Lean women showed, as expected, low waist-to-hip circumference ratio and abdominal sagittal diameter as well as absence of other disease risk factors. Compared with the remaining women, 17β-estradiol was high and androgens were low, whereas insulin-like growth factor I and thyroid hormones showed no differences. Dihydroepiandrosterone sulfate was lower, whereas cortisol, measured in saliva repeatedly over a day, and adrenocorticotropin hormone were not different. Results from questionnaires indicated higher education and socioeconomic status, frequent sports activities, and better psychosocial adaptation and psychological health. A tetranucleotide repeat polymorphism in the fifth intron of the aromatase P450 gene was longer among the lean (187 base pairs) than the rest of the women. Women with opposite phylogenetic characteristic have a short microsatellite (168 base pairs) in this gene locus. Discussion: Lean, nonsmoking women enjoy an excellent health in not only anthropometric and metabolic factors, but also in neuroendocrine, endocrine, and psychological variables. The endocrine measurements suggest a well-functioning aromatase, which in turn might have a genetic background, contributing to health. The aromatase gene might be important for regulation of body fat mass.     

The Hirsute Woman: Challenges in Evaluation and Management

ObjectiveTo review the etiology, pathogenesis, diagnostic approach, and management of hirsutism.MethodsWe discuss the clinical course of hirsutism and provide our recommendations on the various treatment options available.ResultsHirsutism is a common clinical problem characterized by the presence of increased terminal hair growth in androgen-dependent areas of the skin. The development of hirsutism depends on the presence of the pilosebaceous unit, which is genetically determined, as well as the presence of the androgen receptor and intracellular 5α-reductase activity, which converts testosterone to its more active metabolite, dihydrotestosterone. A detailed history and physical examination and the following laboratory tests can diagnose most causes of hirsutism: early-morning follicular phase measurement of total testosterone, testosterone not bound to sex hormone-binding globulin, dehydroepiandrosterone sulfate, 17-hydroxypro- gesterone, prolactin, and thyrotropin levels. Oral contraceptive preparations may be effective monotherapy formild hirsutism. For the treatment of more severe hirsutism, oral contraceptive pills combined with spironolactone are as effective as oral contraceptive pills containing cyproter- one acetate, which are not available in the United States. Because of teratogenicity, spironolactone should be used with caution in premenopausal women when it is administered without an oral contraceptive pill. Metformin is an alternative therapy for hirsutism in women with polycystic ovary syndrome who have other indications for metformin use. Metformin is not as effective as antiandrogens for the management of hirsutism. The use of glucocorticoids, finasteride, or flutamide is not recommended.ConclusionsHirsutism can be evaluated with a detailed history and physical examination and a limited number of hormonal tests. Serious disorders presenting as hirsutism are rare and can be excluded with the recommended evaluation. Treatment is targeted at reducing the production and bioavailability of testosterone, as well as blocking target tissue androgen action. (Endocr Pract. 2011;17:807-818)     

The Woman in the Surgeon's Body: Understanding Difference

Praxis is not simply about learning cultural rules by rote, it is about coming to an understanding of social distinctions through your body.
Much of clinical and practical knowledge [in medicine] is embodied knowledge-knowledge sensed through and with the body. This includes senses of sight, sound, touch, smell.     

The Rb tumor suppressor is required for stress erythropoiesis

The retinoblastoma tumor suppressor gene plays important roles in cell cycle control, differentiation and survival during development and is functionally inactivated in most human cancers. Early studies using gene targeting in mice suggested a critical role for pRb in erythropoiesis, while more recent experiments have suggested that many of the abnormal embryonic phenotypes in the Rb null mouse result from a defective placenta. To address this controversy and determine whether Rb has cell intrinsic functions in erythropoiesis, we examined the effects of Rb loss on red cell production following acute deletion of pRb in vitro and under different stress conditions in vivo. Under stress conditions, pRb was required to regulate erythroblast expansion and promote red cell enucleation. Acute deletion of Rb in vitro induced erythroid cell cycle and differentiation defects similar to those observed in vivo. These results demonstrate a cell intrinsic role for pRb in stress erythropoiesis and hematopoietic homeostasis that has relevance for human diseases.     

The Drosophila HOAP protein is required for telomere capping

HOAP (HP1/ORC-associated protein) has recently been isolated from Drosophila melanogaster embryos as part of a cytoplasmic complex that contains heterochromatin protein 1 (HP1) and the origin recognition complex subunit 2 (ORC2). Here, we show that caravaggio, a mutation in the HOAP-encoding gene, causes extensive telomere-telomere fusions in larval brain cells, indicating that HOAP is required for telomere capping. Our analyses indicate that HOAP is specifically enriched at mitotic chromosome telomeres, and strongly suggest that HP1 and HOAP form a telomere-capping complex that does not contain ORC2.     

苏云金芽孢杆菌gerA操纵子在芽孢萌发中的作用

芽孢萌发的营养诱导剂通过与特异的萌发受体结合激活下游的萌发过程,从而使芽孢经过一系列的遗传变化及生化反应恢复营养生长.从苏云金芽孢杆菌(Bacillus thuringiensis)中克隆到一个与枯草芽孢杆菌(Bacillus subtilis)gerA操纵子和蜡状芽孢杆菌(Bacillus cereus)gerR操纵子同源的gerA操纵子.苏云金芽孢杆菌gerA操纵子含有3个开放读码框:gerAA、gerAC和gerAB,该操纵子在产孢起始3个小时后开始转录.gerA的破坏阻断了L-丙氨酸诱导的芽孢萌发并且延迟了肌苷诱导的萌发.在L-丙氨酸诱导芽孢萌发的过程中D-环丝氨酸能够提高芽孢的萌发率.     

The INO80 complex is required for damage-induced recombination

The budding yeast INO80 complex has a role in remodeling chromatin structure, and the SWR1 complex replaces a H2A/H2B dimer with a variant dimer, H2A.Z (Htz1)/H2B. It has been reported that these chromatin remodeling complexes contain Arp4 (actin-related protein) and actin in common and are recruited to HO endonuclease-induced DNA double-strand break (DSB) site. Reportedly, Ino80 can evict nucleosomes surrounding a HO-induced DSB; however, it has no apparent role to play in the repair of HO-induced DSB. Here we show that an essential factor for INO80 chromatin remodeling activity, Arp8, is involved in damage-induced sister chromatid recombination and interchromosomal recombination between heteroalleles. In contrast, arp6 mutants are proficient for recombination, indicating that the SWR1 complex does not promote recombination. Our data suggest that the remodeling of chromatin by the INO80 complex facilitates efficient homologous recombination upon DNA damages.