RhoGEFs in cell motility: novel links between Rgnef and focal adhesion kinase

Rho guanine exchange factors (GEFs) are a large, diverse family of proteins defined by their ability to catalyze the exchange of GDP for GTP on small GTPase proteins such as Rho family members. GEFs act as integrators from varied intra- and extracellular sources to promote spatiotemporal activity of Rho GTPases that control signaling pathways regulating cell proliferation and movement. Here we review recent studies elucidating roles of RhoGEF proteins in cell motility. Emphasis is placed on Dbl-family GEFs and connections to development, integrin signaling to Rho GTPases regulating cell adhesion and movement, and how these signals may enhance tumor progression. Moreover, RhoGEFs have additional domains that confer distinctive functions or specificity. We will focus on a unique interaction between Rgnef (also termed Arhgef28 or p190RhoGEF) and focal adhesion kinase (FAK), a non-receptor tyrosine kinase that controls migration properties of normal and tumor cells. This Rgnef-FAK interaction activates canonical GEF-dependent RhoA GTPase activity to govern contractility and also functions as a scaffold in a GEF-independent manner to enhance FAK activation. Recent studies have also brought to light the importance of specific regions within the Rgnef pleckstrin homology (PH) domain for targeting the membrane. As revealed by ongoing Rgnef-FAK investigations, exploring GEF roles in cancer will yield fundamental new information on the molecular mechanisms promoting tumor spread and metastasis.

[Evaluation of nasal mucociliary clearance with a modified saccharin test]

To measure the complex nasal clearance we propose to perform our variation of the Andersen saccharin method as a saccharin liquid test (SLT). The application of 3 molar aqueous sodium saccharin solutions with a Wiretrol capillary on the concha nasalis inferior or media allows simple handling, exact dosage, minimal nasal irritation and an increase in reproducibility. Application of 1 microlitre is sufficient to carry out the test. In the present study 48 healthy volunteers without any nose disease or history of sinusitis showed a saccharin transport rate of 10.4 (SD 4.2) minutes.

[Threshold for electric stimulation of taste in diabetes mellitus]

This paper informs about the electrogustometrically determined stimulus-threshold of gustation in 82 patients with diabetes mellitus in comparison with a group of 107 non-diabetics without disturbance of gustation. The stimulation of the tongue was performed with a unipolar electrode switches as a cathode. The electric impulse was measured in microA and the threshold was found to increase with age, in general. In both groups the thresholds tend to higher values in males in contrast to females as well as smokers opposed to non-smokers. With references to the control group the diabetics showed higher values in the electric taste threshold (statistically significant with P = 0.1%). It was noticed that in the diabetics at the tip of the tongue a higher threshold was present than at the margins of the tongue, being in the inverse ratio to the control group and to normal.

[Olfactometric results of the olfactory function in diabetics]

Olfacto-odorimetrical examinations in 110 diabetics resulted in comparison to an examined control group of 110 rhinologically healthy non-diabetics (patients of an ENT-outpatient department) in olfactory disturbances in the sense of a quantitative dysosmia. The percental ratio of the patients with normosmia to patients with dysosmia in the entire group of diabetics was 23.6 : 76.4 in comparison to 58.2 : 41.8 in the non-diabetics. After the chi2-test the result was a significant difference between the two groups. In the diabetics as well as in the control group a decrease of the olfactory function with growing age which was shown in an increase of the olfactory perceptual threshold could be statistically ascertained. Clear connections between olfactory ability on the one hand and sex, number of births in women, smoker habits, blood sugar content and content of urinary sugar, kind of medication, relative metabolic condition, concomitant diseases and duration of diabetes on the other hand could not be established.

[Determination of the perilymph density in the cochlea of guinea pigs (author's transl)]

The perilymph density of the sc. tympani, sc. vestibuli and the density of liquor cerebrospinalis in guinea-pigs are measured by determination from mass and volume of the fluid column in a glass capillary tube. For the density of perilymph in sc. vest. a value of (formula: see text) in sc. tymp. a value of (formula: see text), and for liquor a value of (formula: see text) was obtained.

[Functional study on the sense of smell in patients with chronic liver disease]

In olfacto-odorimetrical examinations of 32 patients with chronic liver diseases (18 female and 14 male patients at the age of 23 to 77 years) 13 patients with a disturbed olfactory function were found. With one exclusion these patients suffered from liver cirrhosis. On the basis of the anamnesis in 10 of these patients a causal connection between disturbance of smelling and liver disease could be assumed. Out of this group with chronic active hepatitis of 10 patients only 1 patient had a disturbed olfactory function. In 8 patients with disturbed olfactory function suffering from liver cirrhosis a comparison of the olfactometrical findings with activity of GOT and GPT in the serum and the serum bilirubin content showed a correlation between possibilitiy of smelling and serum bilirubin level. Possible causes of appearing olfactory disturbances are demonstrated in short.

[Protein study on perilymph susbstitution during cerebrospinal fluid flow through cochlear aqueduct]

Total protein contents in the perilymphy of Scala vestibuli and Scala tympani as well as in the cerobrospinal fluid (CSF) of guinea-pigs were determined, by which specimens were taken under the following various conditions: With or without subarachnoidal puncture before perilymph collection, by varying the amount of perilymph taken from Scala tympani, by fractionating collection and under post mortem condition. The results suggest that under physiological conditions the CSF also flows through the cochleae aqueduct and the protein concentration in the Scala tympani decreases especially in the basal winding. Because the protein content in CSF is inaverage four times lower than in fluids of the inner ear it is of preference to consider the question of connection between the CSF and the fluids of the inner ear. In the specimens taken the blood contamination was estimated on the basisof erythrocytes in the connection capillaries under microscope. The protein content in the perilymph of Scala vestibuli was found significantly higher in relation to perilymph of Scala tympani.