CIB2 Is a Novel Endogenous Repressor of Atrial Remodeling.

BACKGROUND: Atrial fibrillation (AF) is a highly prevalent condition that can cause or exacerbate heart failure, is an important risk factor for stroke, and is associated with pronounced morbidity and death. Genes uniquely expressed in the atria are known to be essential for maintaining atrial structure and function. Atrial tissue remodeling contributes to arrhythmia recurrence and maintenance. However, the mechanism underlying atrial remodeling remains poorly understood. This study was designed to investigate whether other uncharacterized atrial specific genes play important roles in atrial physiology and arrhythmogenesis. METHODS: RNA-sequencing analysis was used to identify atrial myocyte specific and angiotensin II-responsive genes. Genetically modified, cardiomyocyte-specific mouse models (knockout and overexpression) were generated. In vivo and in vitro electrophysiological, histology, and biochemical analyses were performed to determine the consequences of CIB2 (calcium and integrin binding family member 2 protein) gain and loss of function in the atrium. RESULTS: Using RNA-sequencing analysis, we identified CIB2 as an atrial-enriched protein that is significantly downregulated in the left atria of patients with AF and mouse models of AF from angiotensin II infusion or pressure overload. Using cardiomyocyte-specific Cib2 knockout (Cib2-/-) and atrial myocyte-specific Cib2-overexpressing mouse models, we found that loss of Cib2 enhances AF occurrence, prolongs AF duration, and correlates with a significant increase in atrial fibrosis under stress. Conversely, Cib2 overexpression mitigates AF occurrence and atrial fibrosis triggered by angiotensin II stress. Mechanistically, we revealed that CIB2 competes with and inhibits CIB1-mediated calcineurin activation, thereby negating stress-induced structural remodeling and AF. CONCLUSIONS: Our data suggest that CIB2 represents a novel endogenous and atrial-enriched regulator that protects against atrial remodeling and AF under stress conditions. Therefore, CIB2 may represent a new potential target for treating AF.

Expression of a TMC6-TMC8-CIB1 heterotrimeric complex in lymphocytes is regulated by each of the components.

The TMC genes encode a set of homologous transmembrane proteins whose functions are not well understood. Biallelic mutations in either TMC6 or TMC8 are detected in more than half of cases of the pre-malignant skin disease epidermodysplasia verruciformis (EV). It is controversial whether EV induced by mutations in TMC6 or TMC8 originates from keratinocyte or lymphocyte defects. Quantification of TMC6 and TMC8 RNA levels in various organs revealed that lymphoid tissues have the highest levels of expression of both genes, and custom antibodies confirmed protein expression in mouse lymphocytes. To study the function of these proteins we generated mice with targeted deletion mutant alleles of Tmc6 or Tmc8 Either TMC6 or TMC8 deficiency induced a reduction in apparent molecular weight and/or amount of the other TMC molecule. Co-immunoprecipitation experiments indicated that TMC6 and TMC8 formed a protein complex in mouse and human T cells. MS and biochemical analysis demonstrated that TMC6 and TMC8 additionally interacted with the CIB1 protein to form TMC6-TMC8-CIB1 trimers. We demonstrated that TMC6 and TMC8 regulated CIB1 levels by protecting CIB1 from ubiquitination and proteasomal degradation. Reciprocally, CIB1 was needed for stabilizing TMC6 and TMC8 levels. These results suggest why inactivating mutations in any of the three human genes leads to similar clinical presentations. We also demonstrated that TMC6 and TMC8 levels are drastically lower and the proteins are less active in regulating CIB1 in keratinocytes than in T cells. Our study suggests that defects in lymphocytes may contribute to the etiology and pathogenesis of EV.

The CIB1 transcription factor regulates light- and heat-inducible cell elongation via a two-step HLH/bHLH system.

Light and high temperature promote plant cell elongation. PHYTOCHROME INTERACTING FACTOR4 (PIF4, a typical basic helix-loop-helix [bHLH] transcriptional activator) and the non-DNA binding atypical HLH inhibitors PHYTOCHROME RAPIDLY REGULATED1 (PAR1) and LONG HYPOCOTYL IN FAR-RED 1 (HFR1) competitively regulate cell elongation in response to light conditions and high temperature. However, the underlying mechanisms have not been fully clarified. Here, we show that in Arabidopsis thaliana, the bHLH transcription factor CRYPTOCHROME-INTERACTING BASIC HELIX-LOOP-HELIX 1 (CIB1) positively regulates cell elongation under the control of PIF4, PAR1, and HFR1. Furthermore, PIF4 directly regulates CIB1 expression by interacting with its promoter, and PAR1 and HFR1 interfere with PIF4 binding to the CIB1 promoter. CIB1 activates genes that function in cell elongation, and PAR1 interferes with the DNA binding activity of CIB1, thus suppressing cell elongation. Hence, two antagonistic HLH/bHLH systems, the PIF4-PAR1/HFR1 and CIB1-PAR1 systems, regulate cell elongation in response to light and high temperature. We thus demonstrate the important role of non-DNA binding small HLH proteins in the transcriptional regulation of cell elongation in plants.

Identification of calcium and integrin-binding protein 1 as a novel regulator of production of amyloid ß peptide using CRISPR/Cas9-based screening system.

The aberrant metabolism of amyloid ß peptide (Aß) has been implicated in the etiology of Alzheimer disease (AD). Aß is produced via the sequential cleavage of amyloid precursor protein (APP) by ß- and γ-secretases. However, the precise regulatory mechanism of Aß generation still remains unclear. To gain a better understanding of the molecular mechanism of Aß production, we established a genetic screening method based on the CRISPR/Cas9 system to identify novel regulators of Aß production. We successfully identified calcium and integrin-binding protein 1 (CIB1) as a potential negative regulator of Aß production. The disruption of Cib1 significantly upregulated Aß levels. In addition, immunoprecipitation experiments demonstrated that CIB1 interacts with the γ-secretase complex. Moreover, the disruption of Cib1 specifically reduced the cell-surface localization of mature Nicastrin (Nct), which is a component of the γ-secretase complex, without changing the intrinsic activity of γ-secretase. Finally, we confirmed using the single-cell RNA-seq data in human that CIB1 mRNA level in neuron was decreased in the early stage of AD. Taken together, our results indicate that CIB1 regulates Aß production via controlling the subcellular localization of γ-secretase, suggesting CIB1 is involved in the development of AD.

Light-activated protein interaction with high spatial subcellular confinement.

Methods to acutely manipulate protein interactions at the subcellular level are powerful tools in cell biology. Several blue-light-dependent optical dimerization tools have been developed. In these systems one protein component of the dimer (the bait) is directed to a specific subcellular location, while the other component (the prey) is fused to the protein of interest. Upon illumination, binding of the prey to the bait results in its subcellular redistribution. Here, we compared and quantified the extent of light-dependent dimer occurrence in small, subcellular volumes controlled by three such tools: Cry2/CIB1, iLID, and Magnets. We show that both the location of the photoreceptor protein(s) in the dimer pair and its (their) switch-off kinetics determine the subcellular volume where dimer formation occurs and the amount of protein recruited in the illuminated volume. Efficient spatial confinement of dimer to the area of illumination is achieved when the photosensitive component of the dimerization pair is tethered to the membrane of intracellular compartments and when on and off kinetics are extremely fast, as achieved with iLID or Magnets. Magnets and the iLID variants with the fastest switch-off kinetics induce and maintain protein dimerization in the smallest volume, although this comes at the expense of the total amount of dimer. These findings highlight the distinct features of different optical dimerization systems and will be useful guides in the choice of tools for specific applications.

CIB1 and CO interact to mediate CRY2-dependent regulation of flowering.

Cryptochromes are photolyase-like photoreceptors. Arabidopsis CRY2 (cryptochrome 2) primarily mediates the photoperiodic regulation of floral initiation. CRY2 has been shown to promote FT (FLOWERING LOCUS T) mRNA expression in response to blue light by suppressing the degradation of the CO (CONSTANS) protein and activating CIB1 (CRY2-interacting bHLH1). Although CIB1 and CO are both transcriptional activators of FT, their relationship is unknown. Here, we show that CIB1 physically interacts with CO and promotes FT transcription in a CO-dependent manner. CRY2, CIB1, and CO form a protein complex in response to blue light to activate FT transcription, and the complex is regulated by the photoperiod and peaks at dusk along with higher FT expression. We also determined that CRY2 was recruited to the FT chromatin by CIB1 and CO and that all three proteins are bound to the same region within the FT promoter. Therefore, there is crosstalk between the CRY2-CO and CRY2-CIBs pathways, and CIB1 and CO act together to regulate FT transcription and flowering.

Calcium-induced dissociation of CIB1 from ASK1 regulates agonist-induced activation of the p38 MAPK pathway in platelets.

Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that regulates activation of the c-Jun N-terminal kinase (JNK)- and p38-stress response pathways leading to apoptosis in nucleated cells. We have previously shown that ASK1 is expressed in platelets and regulates agonist-induced platelet activation and thrombosis. However, the mechanism by which platelet agonists cause activation of ASK1 is unknown. Here, we show that in platelets agonist-induced activation of p38 is exclusively dependent on ASK1. Both thrombin and collagen were able to activate ASK1/p38. Activation of ASK1/p38 was strongly dependent on thromboxane A2 (TxA2) and ADP. Agonist-induced ASK1 activation is blocked by inhibition of phospholipase C (PLC) ß/γ activity or by chelating intracellular Ca2+. Furthermore, treatment of platelets with thapsigargin or Ca2+ ionophore robustly induced ASK1/p38 activation. In addition, calcium and integrin-binding protein 1 (CIB1), a Ca2+-dependent negative regulator of ASK1, associates with ASK1 in resting platelets and is dissociated upon platelet activation by thrombin. Dissociation of CIB1 corresponds with ASK1 binding to tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6) and the autophosphorylation of ASK1 Thr838 within the catalytic domain results in full activation of ASK1. Furthermore, genetic ablation of Cib1 in mice augments agonist-induced Ask1/p38 activation. Together our results suggest that in resting platelets ASK1 is bound to CIB1 at low Ca2+ concentrations. Agonist-induced platelet activation causes an increase in intracellular Ca2+ concentration that leads to the dissociation of CIB1 from ASK1, allowing for proper dimerization through ASK1 N-terminal coiled-coil (NCC) domains.

Cytosolic interaction of type III human CD38 with CIB1 modulates cellular cyclic ADP-ribose levels.

CD38 catalyzes the synthesis of the Ca2+ messenger, cyclic ADP-ribose (cADPR). It is generally considered to be a type II protein with the catalytic domain facing outside. How it can catalyze the synthesis of intracellular cADPR that targets the endoplasmic Ca2+ stores has not been resolved. We have proposed that CD38 can also exist in an opposite type III orientation with its catalytic domain facing the cytosol. Here, we developed a method using specific nanobodies to immunotarget two different epitopes simultaneously on the catalytic domain of the type III CD38 and firmly established that it is naturally occurring in human multiple myeloma cells. Because type III CD38 is topologically amenable to cytosolic regulation, we used yeast-two-hybrid screening to identify cytosolic Ca2+ and integrin-binding protein 1 (CIB1), as its interacting partner. The results from immunoprecipitation, ELISA, and bimolecular fluorescence complementation confirmed that CIB1 binds specifically to the catalytic domain of CD38, in vivo and in vitro. Mutational studies established that the N terminus of CIB1 is the interacting domain. Using shRNA to knock down and Cas9/guide RNA to knock out CIB1, a direct correlation between the cellular cADPR and CIB1 levels was demonstrated. The results indicate that the type III CD38 is functionally active in producing cellular cADPR and that the activity is specifically modulated through interaction with cytosolic CIB1.

Insight into the Roles of E3 Ubiquitin Ligase c-Cbl, ESCRT Machinery, and Host Cell Signaling in Kaposi's Sarcoma-Associated Herpesvirus Entry and Trafficking.

Kaposi's sarcoma-associated herpesvirus (KSHV) in vitro infection of dermal endothelial cells begins with its binding to host cell surface receptor molecules such as heparan sulfate (HS), integrins (α3ß1, αVß3, and αVß5), xCT, and EphA2 receptor tyrosine kinase (EphA2R). These initial events initiate dynamic host protein-protein interactions involving a multimolecular complex of receptors, signal molecules (focal adhesion kinase [FAK], Src, phosphatidylinositol 3-kinase [PI3-K], and RhoA-GTPase), adaptors (c-Cbl, CIB1, Crk, p130Cas, and GEF-C3G), actin, and myosin II light chain that lead to virus entry via macropinocytosis. Here we discuss how KSHV hijacks c-Cbl, an E3 ubiquitin ligase, to monoubiquitinate the receptors and actin, which acts like a marker for trafficking (similar to zip codes), resulting in the recruitment of the members of the host endosomal sorting complexes required for transport (ESCRT) Hrs, Tsg101, EAP45, and the CHMP5 and -6 proteins (zip code readers) recognizing the ubiquitinated protein and adaptor machinery to traffic through the different endosomal compartments in the cytoplasm to initiate the macropinocytic process and infection.

CIB1 depletion with docetaxel or TRAIL enhances triple-negative breast cancer cell death.

BACKGROUND: Patients diagnosed with triple negative breast cancer (TNBC) have limited treatment options and often suffer from resistance and toxicity due to chemotherapy. We previously found that depleting calcium and integrin-binding protein 1 (CIB1) induces cell death selectively in TNBC cells, while sparing normal cells. Therefore, we asked whether CIB1 depletion further enhances tumor-specific killing when combined with either the commonly used chemotherapeutic, docetaxel, or the cell death-inducing ligand, TRAIL. METHODS: We targeted CIB1 by RNA interference in MDA-MB-436, MDA-MB-231, MDA-MB-468, docetaxel-resistant MDA-MB-436 TNBC cells and ME16C normal breast epithelial cells alone or combination with docetaxel or TRAIL. Cell death was quantified via trypan blue exclusion using flow cytometry and cell death mechanisms were analyzed by Western blotting. Cell surface levels of TRAIL receptors were measured by flow cytometry analysis. RESULTS: CIB1 depletion combined with docetaxel significantly enhanced tumor-specific cell death relative to each treatment alone. The enhanced cell death strongly correlated with caspase-8 activation, a hallmark of death receptor-mediated apoptosis. The death receptor TRAIL-R2 was upregulated in response to CIB1 depletion, which sensitized TNBC cells to the ligand TRAIL, resulting in a synergistic increase in cell death. In addition to death receptor-mediated apoptosis, both combination treatments activated a non-apoptotic mechanism, called paraptosis. Interestingly, these combination treatments also induced nearly complete death of docetaxel-resistant MDA-MB-436 cells, again via apoptosis and paraptosis. In contrast, neither combination treatment induced cell death in normal ME16C cells. CONCLUSION: Novel combinations of CIB1 depletion with docetaxel or TRAIL selectively enhance naive and docetaxel-resistant TNBC cell death while sparing normal cell. Therefore, combination therapies that target CIB1 could prove to be a safe and durable strategy for treatment of TNBC and potentially other cancers.

The Emerging Roles of CIB1 in Cancer.

Calcium and integrin-binding protein 1 (CIB1) is an EF-hand calcium binding protein, which is involved in many cellular processes, including calcium signaling, cell survival and proliferation, cell migration, cell adhesion and apoptosis. A number of studies have found that CIB1 is ubiquitously expressed and is related to various human diseases, such as cancer, Alzheimer's disease (AD), cardiac hypertrophy and male infertility. The mechanism of CIB1 in human diseases is still not clear, although multiple functions of CIB1 are modulated by interacting with numerous interacting partners. As a calcium binding protein, the roles of CIB1 in calcium signaling by binding calcium or modulating some key modulators, such as calcineurin, integrin, inositol 1,4,5-trisphosphate receptor (IP3R) and taste 1 receptor member 2 (TAS1R2). The tumor promoting mechanisms of CIB1 have been described in different aspects, including promoting tumor cell cycle and proliferation, inhibiting tumor cell apoptosis, and mediating tumor cell migration and angiogenesis. In addition, multiple functions of CIB1, such as neural development, taste or gustation functions, and virus infection are also elucidated. These recent advances have significantly expanded our understanding of the knowledge of CIB1 and highlighted the potential mechanisms of CIB1 in tumor progression.

Quantitative real-time kinetics of optogenetic proteins CRY2 and CIB1/N using single-molecule tools.

In this work we evaluate the interaction of two optogenetic protein variants (CIB1, CIBN) with their complementary protein CRY2 by single-molecule tools in cell-free extracts. After validating the blue light induced co-localization of CRY2 and CIB1/N by Förster resonance energy transfer (FRET) in live cells, a fluorescence correlation spectroscopy (FCS) based method was developed to quantitatively determine the in vitro association of the extracted proteins. Our experiments suggest that CIB1, in comparison with CIBN, possesses a better coupling efficiency with CRY2 due to its intact protein structure and lower diffusion rate within 300s detection window.

Deubiquitination of CIB1 by USP14 promotes lenvatinib resistance via the PAK1-ERK1/2 axis in hepatocellular carcinoma.

Background: Lenvatinib is the most common multitarget receptor tyrosine kinase inhibitor for the treatment of advanced hepatocellular carcinoma (HCC). Acquired resistance to lenvatinib is one of the major factors leading to the failure of HCC treatment, but the underlying mechanism has not been fully characterized. Methods: We established lenvatinib-resistant cell lines, cell-derived xenografts (CDXs) and patient-derived xenografts (PDXs) and obtained lenvatinib-resistant HCC tumor tissues for further study. Results: We found that ubiquitin-specific protease 14 (USP14) was significantly increased in lenvatinib-resistant HCC cells and tumors. Silencing USP14 significantly attenuated lenvatinib resistance in vitro and in vivo. Mechanistically, USP14 directly interacts with and stabilizes calcium- and integrin-binding protein 1 (CIB1) by reversing K48-linked proteolytic ubiquitination at K24, thus facilitating the P21-activated kinase 1 (PAK1)-ERK1/2 signaling axis. Moreover, in vivo adeno-associated virus 9 mediated transduction of CIB1 promoted lenvatinib resistance in PDXs, whereas CIB1 knockdown resensitized the response of PDXs to lenvatinib. Conclusions: These findings provide new insights into the role of CIB1/PAK1-ERK1/2 signaling in lenvatinib resistance in HCC. Targeting CIB1 and its pathways may be a novel pharmaceutical intervention for the treatment of lenvatinib-resistant HCC.

High CIB1 expression in colorectal cancer liver metastases correlates with worse survival and the replacement histopathological growth pattern.

To date, nearly one-quarter of colorectal cancer (CRC) patients develop liver metastases (CRCLM), and its aggressiveness can be correlated to defined histopathological growth patterns (HGP). From the three main HGPs within CRCLM, the replacement HGP emerges as particularly aggressive, characterized by heightened tumor cell motility and vessel co-option. Here, we investigated the correlation between the expression of calcium- and integrin-binding protein 1 (CIB1), a ubiquitously expressed gene involved in various cellular processes including migration and adhesion, and disease-free (DFS) and overall survival (OS) in primary CRC patients. Additionally, we explored the correlation between CIB1 expression and different HGPs of CRCLM. Proteomic analysis was used to evaluate CIB1 expression in a cohort of 697 primary CRC patients. Additionally, single-cell and spatial RNA-sequencing datasets, along with publicly available bulk sequencing data were used to evaluate CIB1 expression in CRCLM. In silico data were further validated by formalin-fixed paraffin-embedded immunohistochemical stainings. We observed that high CIB1 expression is independently associated with worse DFS and OS, regardless of Union Internationale Contre le Cancer stage, gender, or age. Furthermore, the aggressive replacement CRCLM HGP is significantly associated with high CIB1 expression. Our findings show a correlation between CIB1 levels and the clinical aggressiveness of CRC. Moreover, CIB1 may be a novel marker to stratify HGP CRCLM.

Identification of calcium and integrin-binding protein 1 as a reprogrammed glucose metabolism mediator to restrict immune cell infiltration in the stromal compartment of pancreatic ductal adenocarcinoma.

An increasing body of evidence has suggested that reprogrammed metabolism plays a critical role in the progression of pancreatic ductal adenocarcinoma (PDAC) by affecting the tumor and stromal cellular components in the tumor microenvironment (TME). By analyzing the KRAS pathway and metabolic pathways, we found that calcium and integrin-binding protein 1 (CIB1) corresponded with upregulation of glucose metabolism pathways and was associated with poor prognosis in patients with PDAC from The Cancer Genome Atlas (TCGA). Elevated CIB1 expression combined with upregulated glycolysis, oxidative phosphorylation (Oxphos), hypoxia pathway activation, and cell cycle promoted PDAC tumor growth and increased tumor cellular com-ponents. Furthermore, we confirmed the mRNA overexpression of CIB1 and co-expression of CIB1 and KRAS mutation in cell lines from the Expression Atlas. Subsequently, immunohistochemistry staining from the Human Protein Atlas (HPA) showed that high expression of CIB1 in tumor cells was associated with an increased tumor compartment and reduced stromal cellular abundance. Furthermore, using multiplexed immunohistochemistry (mIHC), we verified that low stromal abundance was correlated with low infiltration of CD8+ PD-1- T cells which led to suppressed anti-tumor immunity. Overall, our findings identify CIB1 as a metabolic pathway-mediated factor for the restriction of immune cell infiltration in the stromal compartment of PDAC and highlight the potential value of CIB1 as a prognostic biomarker involved in metabolic reprogramming and immune modulation.

In silico Mutagenesis and Modeling of Decoy Peptides Targeting CIB1 to Obscure its Role in Triple-negative Breast Cancer Progression.

BACKGROUND: Cancer is recognized globally as the second-most dominating and leading cause of morbidities. Breast cancer is the most often diagnosed disease in women and one of the leading causes of cancer mortality. In women, 287,850, and in males, 2710 cases were reported in 2022. Approximately 10-20% of all new cases of breast cancer diagnosed in the United States in 2017 were triple-negative breast cancers (TNBCs), which lack the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). OBJECTIVE: This study aims to adopt different strategies for targeting calcium integrin-binding protein 1 by computer- aided drug design methods. Our results showed that the top four selected peptides interact with CIB1 more strongly than the reference peptide and restore normal cell function by engaging CIB1. Our binding affinity analyses explore an innovative approach to planning a new peptide to inhibit triple-negative breast cancer. METHODS: Molecular dynamic simulation of the CIB1-UNC10245092 interaction highlights the potential peptide inhibitors through in-silico mutagenesis and designs novel peptide inhibitors from the reference peptide (UNC10245092) through residue scan methodology. RESULTS: The top four designed peptides (based on binding free energy) were subjected to molecular dynamics simulations using AMBER to evaluate stability. CONCLUSION: Our results indicate that among the top five selected peptides, the mutant 2nd mutants have more potential to inhibit CIB1 than the reference peptide (UNC10245092) and have the potency to prevent or restore the tumor suppressor function of UNC10245092.

Strategies for Targeting CIB1: A Challenging Drug Target.

Breast cancer is a common malignancy in women and is a diverse disease. In women, 287,850 and in males 2710 cases are reported in 2022 by WHO. Triple-negative breast cancer (TNBC), a subtype of breast cancer that lacks expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), accounted for 10-20% of all new cases discovered in the United States in 2017. Because calcium integrin-binding protein1 lacks a suitable pocket that could be used to create a chemical inhibitor, and because the breast cancer-causing protein is nearly identical to its necessary wild-type counterpart, it was thought to be druggable. The structure and function of the newly discovered calcium integrinbinding protein1 have been improved, paving the way for the designing of several therapeutic candidates. Currently, no FDA-approved drugs are available for CIB1-driven cancer. CIB1 has proven to challenge drug target due to several factors, including the fact that the CIB1 protein is highly resistant to small inhibitors. This study aimed to present various ways for targeting calcium integrin-binding protein1, which is an important target that could be useful to scientists.

Optogenetic Control of Membrane Trafficking Using Light-Activated Reversible Inhibition by Assembly Trap of Intracellular Membranes (IM-LARIAT).

Intracellular membrane trafficking is a dynamic and complex cellular process. To study membrane trafficking with a high spatiotemporal resolution, we present an optogenetic method based on a blue-light inducible oligomerization of Rab GTPases, termed light-activated reversible inhibition by assembly trap of intracellular membranes (IM-LARIAT). In this chapter, we focus on the optical disruption of the dynamics and functions of previously studied intracellular membrane trafficking events, including transferrin recycling and growth cone regulation in relation to specific Rab GTPases. To aid general application, we provide a detailed description of transfection, imaging with a confocal microscope, and analysis of data.

Optogenetic Methods to Control Tissue Mechanics in Drosophila.

Optogenetics is a powerful technique that allows the control of protein function with high spatiotemporal precision using light. Here, we describe the application of this method to control tissue mechanics during Drosophila embryonic development. We detail optogenetic protocols to either increase or decrease cell contractility and analyze the interplay between cell-cell interaction, tissue geometry, and force transmission during gastrulation.

Calcium and integrin binding protein 1 (CIB1) induces myocardial fibrosis in myocardial infarction via regulating the PI3K/Akt pathway.

Myocardial infarction (MI) is a severe coronary artery disease resulted from substantial and sustained ischemia. Abnormal upregulation of calcium and integrin binding protein 1 (CIB1) has been found in several cardiovascular diseases. In this study, we established a mouse model of MI by permanent ligation of the left anterior descending coronary artery. CIB1 was upregulated in the heart of MI mice. Notably, CIB1 knockdown by intramuscular injection of lentivirus-mediated short hairpin RNA (shRNA) targeting Cib1 improved cardiac function and attenuated myocardial hypertrophy and infarct area in MI mice. MI-induced upregulation of α-SMA, vimentin, Collagen I, and Collagen III, which resulted in collagen production and myocardial fibrosis, were regressed by CIB1 silencing. In vitro, cardiac fibroblasts (CFs) isolated from mice were subjected to angiotensin II (Ang II) treatment. Inhibition of CIB1 downregulated the expression of α-SMA, vimentin, Collagen I, and Collagen III in Ang II-treated CFs. Moreover, CIB1 knockdown inhibited Ang II-induced phosphorylation of PI3K-p85 and Akt in CFs. The effect of CIB1 knockdown on Ang II-induced cellular injury was comparable to that of LY294002, a specific inhibitor of the PI3K/Akt pathway. We demonstrated that MI-induced cardiac hypertrophy, myocardial fibrosis, and cardiac dysfunction might be attributed to the upregulation of CIB1 in MI mice. Downregulation of CIB1 alleviated myocardial fibrosis and cardiac dysfunction by decreasing the expression of α-SMA, vimentin, Collagen I, and Collagen III via inhibiting the PI3K/Akt pathway. Therefore, CIB1 may be a potential target for MI treatment.