α-Catenin homodimers are recruited to phosphoinositide-activated membranes to promote adhesion.

A unique feature of α-catenin localized outside the cadherin-catenin complex is its capacity to form homodimers, but the subcellular localization and functions of this form of α-catenin remain incompletely understood. We identified a cadherin-free form of α-catenin that is recruited to the leading edge of migrating cells in a phosphatidylinositol 3-kinase-dependent manner. Surface plasmon resonance analysis shows that α-catenin homodimers, but not monomers, selectively bind phosphatidylinositol-3,4,5-trisphosphate-containing lipid vesicles with high affinity, where three basic residues, K488, K493, and R496, contribute to binding. Chemical-induced dimerization of α-catenin containing a synthetic dimerization domain promotes its accumulation within lamellipodia and elaboration of protrusions with extended filopodia, which are attenuated in the α-cateninKKR<3A mutant. Cells restored with a full-length, natively homodimerizing form of α-cateninKKR<3A display reduced membrane recruitment, altered epithelial sheet migrations, and weaker cell-cell adhesion compared with WT α-catenin. These findings show that α-catenin homodimers are recruited to phosphoinositide-activated membranes to promote adhesion and migration, suggesting that phosphoinositide binding may be a defining feature of α-catenin function outside the cadherin-catenin complex.

A randomized, double-blind, placebo-controlled, pilot study to assess the efficacy and safety of clindamycin 1.2% and tretinoin 0.025% combination gel for the treatment of acne rosacea over 12 weeks.

BACKGROUND: Papulopustular acne rosacea is a chronic inflammatory condition which can be difficult to treat. Many patients are unwilling to use systemic medications, and single topical agents alone may not address all the symptoms of rosacea. A combination topical clindamycin phosphate 1.2% and tretinoin 0.025% gel is efficacious for acne vulgaris, and may be helpful for rosacea, since acne vulgaris and rosacea shares many similar clinical and histologic features. OBJECTIVE: To assess the preliminary efficacy and safety of a combination gel consisting of clindamycin phosphate 1.2% and tretinoin 0.025% on papulopustular rosacea after 12 weeks of usage. METHODS: Randomized, double-blind, placebo controlled two site study of 79 participants with moderate to severe papulopustular acne rosacea using both physician and subjects' validated assessment tools. Primary endpoint consisted of statistically significant reduction in absolute papule or pustule count after 12 weeks of usage. RESULTS: There was no significant difference in papule/pustule count between placebo and treated groups after 12 weeks (P=0.10). However, there was nearly significant improvement in physicians' assessments of the telangiectasia component of rosacea (P=0.06) and erythematotelangiectatic rosacea subtype (P=0.05) in treated versus placebo group after 12 weeks. The only significant adverse event different was facial scaling, which was significantly increased in treated group (P=0.01), but this did not result in discontinuation of study drug. CONCLUSIONS: A combination gel of clindamycin phosphate 1.2% and tretinoin 0.025% may improve the telangiectatic component of rosacea and appears to better treat the erythemotelangiectatic subtype of rosacea rather than papulopustular subtype. Our preliminary study suggests that future studies with much larger sample size might confirm our findings.

Overview of hepatitis C and skin.

Hepatitis C (HCV) is the most common cause of chronic liver disease and hepatocellular carcinoma, as well as the leading indication for liver transplantation in the Western world. For many patients, cutaneous manifestations may be the only, the earliest, or the most apparent sign of the underlying infection. The dermatologic manifestations of HCV infection are reviewed.

Thermodynamic stability of a kappaI immunoglobulin light chain: relevance to multiple myeloma.

Immunoglobulin light chains have two similar domains, each with a hydrophobic core surrounded by beta-sheet layers, and a highly conserved disulfide bond. Differential scanning calorimetry and circular dichroism were used to study the folding and stability of MM-kappaI, an Ig LC of kappaI subtype purified from the urine of a multiple myeloma patient. The complete primary structure of MM-kappaI was determined by Edman sequence analysis and mass spectrometry. The protein was found to contain a cysteinyl post-translational modification at Cys(214). Protein stability and conformation of MM-kappaI as a function of temperature or denaturant conditions at pH 7.4 and 4.8 were investigated. At pH 4.8, calorimetry demonstrated that MM-kappaI undergoes an incomplete, cooperative, partially reversible thermal unfolding with increased unfolding temperature and calorimetric enthalpy as compared to pH 7.4. Secondary and tertiary structural analyses provided evidence to support the presence of unfolding intermediates. Chemical denaturation resulted in more extensive protein unfolding. The stability of MM-kappaI was reduced and protein unfolding was irreversible at pH 4.8, thus suggesting that different pathways are utilized in thermal and chemical unfolding.