Dual-LC PSHG microscopy for imaging collagen type I and type II gels with pixel-resolution analysis.

Collagen of type I (Col I) and type II (Col II) are critical for cartilage and connective tissues in the human body, and several diseases may alter their properties. Assessing the identification and quantification of fibrillar collagen without biomarkers is a challenge. Advancements in non-invasive polarization-resolved second-harmonic generation (PSHG) microscopy have provided a method for the non-destructive investigation of collagen molecular level properties. Here we explored an alternative polarization modulated approach, dual-LC PSHG, that is based on two liquid crystal devices (Liquid crystal polarization rotators, LPRs) operating simultaneously with a laser scanning SHG microscope. We demonstrated that this more accessible technology allows the quick and accurate generation of any desired linear and circular polarization state without any mechanical parts. This study demonstrates that this method can aid in improving the ability to quantify the characteristics of both types of collagen, including pitch angle, anisotropy, and circular dichroism analysis. Using this approach, we estimated the effective pitch angle for Col I and Col II to be 49.7° and 51.6°, respectively. The effective peptide pitch angle for Col II gel was first estimated and is similar to the value obtained for Col I gel in the previous studies. Additionally, the difference of the anisotropy parameter of both collagen type gels was assessed to be 0.293, which reflects the different type molecular fibril assembly. Further, our work suggests a potential method for monitoring and differentiating different collagen types in biological tissues, especially cartilage or connective tissue.

The Drosophila LIN54 homolog Mip120 controls two aspects of oogenesis.

The conserved multi-protein MuvB core associates with the Myb oncoproteins and with the RB-E2F-DP tumor suppressor proteins in complexes that regulate cell proliferation, differentiation, and apoptosis. Drosophila Mip120, a homolog of LIN54, is a sequence-specific DNA-binding protein within the MuvB core. A mutant of Drosophilamip120 was previously shown to cause female and male sterility. We now show that Mip120 regulates two different aspects of oogenesis. First, in the absence of the Mip120 protein, egg chambers arrest during the transition from stage 7 to 8 with a failure of the normal program of chromosomal dynamics in the ovarian nurse cells. Specifically, the decondensation, disassembly and dispersion of the endoreplicated polytene chromosomes fail to occur without Mip120. The conserved carboxy-terminal DNA-binding and protein-protein interaction domains of Mip120 are necessary but not sufficient for this process. Second, we show that a lack of Mip120 causes a dramatic increase in the expression of benign gonial cell neoplasm (bgcn), a gene that is normally expressed in only a small number of cells within the ovary including the germline stem cells.

Acid-sensing ion channel 3, but not capsaicin receptor TRPV1, plays a protective role in isoproterenol-induced myocardial ischemia in mice.

BACKGROUND: Cardiac angina is the hallmark of myocardial ischemia, but the role of the cardiac sensory nerve has received relatively little attention. Recently, both acid-sensing ion channel 3 (ASIC3) and capsaicin receptor (TRPV1) have been suggested as important mediators in sensing cardiac ischemia. However, studies comparing the physiological roles of ASIC3 and TRPV1 in the neuronal-cardiac sensing circuits in vivo are lacking. METHODS AND RESULTS: Isoproterenol (1.5 mg/kg, intraperitoneally) was used to induce transient cardiac ischemia in Asic3(+/+) and Asic3(-/-) mice and a radio-telemetry system was used for electrocardiography with mice in a conscious state. Isoproterenol-induced cardiac ischemia was first demonstrated with ST-segment depression and further confirmed by hypoxia-mediated chemical reactions in cardiac tissue. Mice lacking Asic3 showed prolonged duration of ST-segment depression compared with Asic3(+/+) mice (44.3 ± 3.1 vs. 31.7 ± 2.9 min; P < 0.05). Although ischemia was transient, severe cardiac fibrosis was found in Asic3(-/-) but not in Asic3(+/+) mice littermates. In contrast, isoproterenol-injected Trpv1(+/+) and Trpv1(-/-) mice showed no difference in duration of ST-segment depression and, surprisingly, deletion of Trpv1 did not aggravate cardiac fibrosis. CONCLUSIONS: An isoproterenol-induced cardiac ischemia model mimicking clinical conditions of early cardiac angina was used to demonstrate that ASIC3 but not TRPV1 plays a protective role in sensing cardiac ischemia.

Chronic cisplatin treatment promotes enhanced damage repair and tumor progression in a mouse model of lung cancer.

Chemotherapy resistance is a major obstacle in cancer treatment, yet the mechanisms of response to specific therapies have been largely unexplored in vivo. Employing genetic, genomic, and imaging approaches, we examined the dynamics of response to a mainstay chemotherapeutic, cisplatin, in multiple mouse models of human non-small-cell lung cancer (NSCLC). We show that lung tumors initially respond to cisplatin by sensing DNA damage, undergoing cell cycle arrest, and inducing apoptosis-leading to a significant reduction in tumor burden. Importantly, we demonstrate that this response does not depend on the tumor suppressor p53 or its transcriptional target, p21. Prolonged cisplatin treatment promotes the emergence of resistant tumors with enhanced repair capacity that are cross-resistant to platinum analogs, exhibit advanced histopathology, and possess an increased frequency of genomic alterations. Cisplatin-resistant tumors express elevated levels of multiple DNA damage repair and cell cycle arrest-related genes, including p53-inducible protein with a death domain (Pidd). We demonstrate a novel role for PIDD as a regulator of chemotherapy response in human lung tumor cells.