mAbs to receptor tyrosine kinases such as EGF receptor͞ErbB-1 and HER2͞ErbB-2 inhibit the tumorigenic growth of certain cancer cells, but although recombinant versions of such Abs are already used in oncology wards, the mechanism underlying immunotherapy remains unknown. We report that anti-EGF receptor Abs promote a slow endocytic process distinct from the rapid EGF-induced receptor internalization. Combining mAbs that engage distinct epitopes significantly accelerates receptor degradation. In addition, mAb combinations are more effective than single Abs in inhibiting HER2 signaling in vitro and tumorigenesis in animals. We present a model attributing efficacy of immunotherapy to the size of Abreceptor lattices formed at the cell surface, which dictates the rate of endocytic clearance and extent of signaling blockade.ErbB ͉ growth factor ͉ oncogene ͉ signal transduction ͉ antibody T he four receptor tyrosine kinases of the ErbB family and their multiple ligand molecules form a layered signaling network, which is implicated in human cancer (reviewed in ref.1): overexpression of ErbB-1͞EGF receptor (EGFR) has been implicated as a feature of poor prognosis in various human malignancies. Moreover, deletion mutants of EGFR exist in brain tumors and point mutations have recently been reported in lung cancer (2). By contrast, ErbB-2͞HER2 is rarely mutated in solid tumors. Instead, the erbB-2 gene is frequently amplified in breast, ovarian, and lung cancer (3). Because of their oncogenic potential and accessibility, ErbB proteins have emerged as attractive targets for pharmaceutical interventions. One major strategy involves the use of mAbs. Early studies uncovered the tumor-inhibitory potential of mAbs directed at ErbB-1 and ErbB-2 (4, 5), and later studies indicated that anti-ErbB mAbs are effective when combined with various chemotherapeutic agents (6, 7). Indeed, the clinical benefit of combining mAbs with certain chemotherapeutic agents was notable, which led to the approval of mAbs to ErbB-2 (Herceptin) and EGFR (C225͞ Cetuximab) for the treatment of breast and colorectal cancer, respectively.Two types of mechanisms have been implicated in ErbBdirected immunotherapy. The first involves mAb-mediated recruitment to tumors of natural killer cells through the Fc-␥ activation receptors of these immune effector cells (8). The second type of mechanisms relates to intrinsic mAb activities, which include blockade of ligand binding or receptor heterodimerization (9), inhibition of downstream signaling to Akt (10), and acceleration of receptor internalization (11,12). The latter mechanism is particularly attractive because ligand-induced endocytosis and degradation of active receptor tyrosine kinases (RTKs) is considered a major physiological process underlying attenuation of growth-promoting signals (13).Several studies reported cooperative effects of mAb combinations (9, 12, 14-16), whereas others found that bivalent, Fc-lacking versions of anti-ErbB mAbs inhibit tumorigenic growth in animals (17, 18). These observations ...

MicroRNAs (miRNAs) inhibit the translation of target mRNAs and affect, directly or indirectly, the expression of a large portion of the protein-coding genes. This study focuses on miRNAs that are expressed in the mouse cochlea and vestibule, the 2 inner ear compartments. A conditional knock-out mouse for Dicer1 demonstrated that miRNAs are crucial for postnatal survival of functional hair cells of the inner ear. We identified miRNAs that have a role in the vertebrate developing inner ear by combining miRNA transcriptome analysis, spatial and temporal expression patterns, and bioinformatics. Microarrays revealed similar miRNA profiles in newborn-mouse whole cochleae and vestibules, but different temporal and spatial expression patterns of six miRNAs (miR-15a, miR-18a, miR-30b, miR-99a, miR-182, and miR-199a) may reflect their roles. Two of these miRNAs, miR-15a-1 and miR-18a, were also shown to be crucial for zebrafish inner ear development and morphogenesis. To suggest putative target mRNAs whose translation may be inhibited by selected miRNAs, we combined bioinformatics-based predictions and mRNA expression data. Finally, we present indirect evidence that Slc12a2, Cldn12, and Bdnf mRNAs may be targets for miR-15a. Our data support the hypothesis that inner ear tissue differentiation and maintenance are regulated and controlled by conserved sets of cell-specific miRNAs in both mouse and zebrafish.cochlea ͉ deafness ͉ Dicer ͉ mouse ͉ zebrafish

Hereditary hearing loss is the most common sensory deficit. We determined that progressive high-frequency hearing loss in 2 families of Iraqi Jewish ancestry was due to homozygosity for the protein truncating mutation SYNE4 c.228delAT. SYNE4, a gene not previously associated with hearing loss, encodes nesprin-4 (NESP4), an outer nuclear membrane (ONM) protein expressed in the hair cells of the inner ear. The truncated NESP4 encoded by the families' mutation did not localize to the ONM. NESP4 and SUN domain-containing protein 1 (SUN1), which localizes to the inner nuclear membrane (INM), are part of the linker of nucleoskeleton and cytoskeleton (LINC) complex in the nuclear envelope. Mice lacking either Nesp4 or Sun1 were evaluated for hair cell defects and hearing loss. In both Nesp4 -/-and Sun1 -/-mice, OHCs formed normally, but degenerated as hearing matured, leading to progressive hearing loss. The nuclei of OHCs from mutant mice failed to maintain their basal localization, potentially affecting cell motility and hence the response to sound. These results demonstrate that the LINC complex is essential for viability and normal morphology of OHCs and suggest that the position of the nucleus in sensory epithelial cells is critical for maintenance of normal hearing.

Recent reports suggest that 10-30% of SARS-CoV-2 infected patients are asymptomatic and that significant viral shedding may occur prior to symptom onset. Therefore, there is an urgent need to increase diagnostic testing capabilities to prevent disease spread. We developed P-BEST - a method for Pooling-Based Efficient SARS-CoV-2 Testing which identifies all positive subjects within a large set of samples using a single round of testing. Each sample is assigned into multiple pools using a combinatorial pooling strategy based on compressed sensing designed for maximizing carrier detection. In our current study we pooled sets of 384 samples into 48 pools providing both an 8-fold increase in testing efficiency, as well as an 8-fold reduction in test costs. We successfully identified up to 5 positive carriers within sets of 384 samples. We then used P-BEST to screen 1115 healthcare workers using 144 tests. P-BEST provides an efficient and easy-to-implement solution for increasing testing capacity that can be easily integrated into diagnostic laboratories.