Cysteine-rich Intestinal Protein Research Articles

Cysteine Rich Intestinal Protein 2 is a copper-responsive regulator of skeletal muscle differentiation and metal homeostasis.

Copper (Cu) is essential for respiration, neurotransmitter synthesis, oxidative stress response, and transcription regulation, with imbalances leading to neurological, cognitive, and muscular disorders. Here we show the role of a novel Cu-binding protein (Cu-BP) in mammalian transcriptional regulation, specifically on skeletal muscle differentiation using murine primary myoblasts. Utilizing synchrotron X-ray fluorescence-mass spectrometry, we identified murine cysteine-rich intestinal protein 2 (mCrip2) as a key Cu-BP abundant in both nuclear and cytosolic fractions. mCrip2 binds two to four Cu+ ions with high affinity and presents limited redox potential. CRISPR/Cas9-mediated deletion of mCrip2 impaired myogenesis, likely due to Cu accumulation in cells. CUT&RUN and transcriptome analyses revealed its association with gene promoters, including MyoD1 and metallothioneins, suggesting a novel Cu-responsive regulatory role for mCrip2. Our work describes the significance of mCrip2 in skeletal muscle differentiation and metal homeostasis, expanding understanding of the Cu-network in myoblasts. Copper (Cu) is essential for various cellular processes, including respiration and stress response, but imbalances can cause serious health issues. This study reveals a new Cu-binding protein (Cu-BP) involved in muscle development in primary myoblasts. Using unbiased metalloproteomic techniques and high throughput sequencing, we identified mCrip2 as a key Cu-BP found in cell nuclei and cytoplasm. mCrip2 binds up to four Cu+ ions and has a limited redox potential. Deleting mCrip2 using CRISPR/Cas9 disrupted muscle formation due to Cu accumulation. Further analyses showed that mCrip2 regulates the expression of genes like MyoD1, essential for muscle differentiation, and metallothioneins in response to copper supplementation. This research highlights the importance of mCrip2 in muscle development and metal homeostasis, providing new insights into the Cu-network in cells.

CRIP1 regulates osteogenic differentiation of bone marrow stromal cells and pre-osteoblasts via the Wnt signaling pathway

With the aging of the global demographic, the prevention and treatment of osteoporosis are becoming crucial issues. The gradual loss of self-renewal and osteogenic differentiation capabilities in bone marrow stromal cells (BMSCs) is one of the key factors contributing to osteoporosis. To explore the regulatory mechanisms of BMSCs differentiation, we collected bone marrow cells of femoral heads from patients undergoing total hip arthroplasty for single-cell RNA sequencing analysis. Single-cell RNA sequencing revealed significantly reduced CRIP1 (Cysteine-Rich Intestinal Protein 1) expression and osteogenic capacity in the BMSCs of osteoporosis patients compared to non-osteoporosis group. CRIP1 is a gene that encodes a member of the LIM/double zinc finger protein family, which is involved in the regulation of various cellular processes including cell growth, development, and differentiation. CRIP1 knockdown resulted in decreased alkaline phosphatase activity, mineralization and expression of osteogenic markers, indicating impaired osteogenic differentiation. Conversely, CRIP1 overexpression, both in vitro and in vivo, enhanced osteogenic differentiation and rescued bone mass reduction in ovariectomy-induced osteoporosis mice model. The study further established CRIP1's modulation of osteogenesis through the Wnt signaling pathway, suggesting that targeting CRIP1 could offer a novel approach for osteoporosis treatment by promoting bone formation and preventing bone loss.

CRIP1 fosters MDSC trafficking and resets tumour microenvironment via facilitating NF-κB/p65 nuclear translocation in pancreatic ductal adenocarcinoma

ObjectivePancreatic ductal adenocarcinoma (PDAC) is among the most immunosuppressive tumour types. The tumour immune microenvironment (TIME) is largely driven by interactions between immune cells and heterogeneous tumour cells. Here, we...

Cysteine-rich intestinal protein 1 is a novel surface marker for human myometrial stem/progenitor cells

Myometrial stem/progenitor cells (MyoSPCs) have been proposed as the cells of origin for uterine fibroids, but the identity of the MyoSPC has not been well established. We previously identified SUSD2 as a possible MyoSPC marker, but the relatively poor enrichment in stem cell characteristics of SUSD2+ over SUSD2- cells compelled us to find better markers. We combined bulk RNA-seq of SUSD2+/- cells with single cell RNA-seq to identify markers for MyoSPCs. We observed seven distinct cell clusters within the myometrium, with the vascular myocyte cluster most highly enriched for MyoSPC characteristics and markers. CRIP1 expression was found highly upregulated by both techniques and was used as a marker to sort CRIP1+/PECAM1- cells that were both enriched for colony forming potential and able to differentiate into mesenchymal lineages, suggesting that CRIP1+/PECAM1- cells could be used to better study the etiology of uterine fibroids.

CRIP1 supports the growth and migration of AML-M5 subtype cells by activating Wnt/β-catenin pathway

Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous hematopoietic disorder. To effectively eradicate AML, it is urgent to develop new therapeutic approaches and identify novel molecular targets. In silico analysis indicated that the expression of cysteine-rich intestinal protein 1 (CRIP1) was significantly elevated in AML cells and correlated with worse overall survival of the AML patients. However, its specific roles in AML remain elusive. Here we demonstrated that CRIP1 acted as a key oncogene to support AML cell survival and migration. Using a loss-of-function analysis, we found that CRIP1 silencing in U937 and THP1 cells by lentivirus-mediated shRNAs resulted in a decrease in cell growth, migration and colony formation, and an increase in chemosensitivity to Ara-C. CRIP1 silencing induced cell apoptosis and G1/S transition arrest. Mechanically, CRIP1 silencing caused inactivation of Wnt/β-catenin pathway through upregulating axin1 protein. The Wnt/β-catenin agonist SKL2001 markedly rescued the cell growth and migration defect induced by CRIP1 silencing. Our findings reveals that CRIP1 may contribute to AML-M5 pathogenesis and represent a novel target for AML-M5 treatment.

Comprehensive bioinformatics analysis reveals biomarkers of DNA methylation-related genes in varicose veins.

Background: Patients with Varicose veins (VV) show no obvious symptoms in the early stages, and it is a common and frequent clinical condition. DNA methylation plays a key role in VV by regulating gene expression. However, the molecular mechanism underlying methylation regulation in VV remains unclear. Methods: The mRNA and methylation data of VV and normal samples were obtained from the Gene Expression Omnibus (GEO) database. Methylation-Regulated Genes (MRGs) between VV and normal samples were crossed with VV-associated genes (VVGs) obtained by weighted gene co-expression network analysis (WGCNA) to obtain VV-associated MRGs (VV-MRGs). Their ability to predict disease was assessed using receiver operating characteristic (ROC) curves. Biomarkers were then screened using a random forest model (RF), support vector machine model (SVM), and generalized linear model (GLM). Next, gene set enrichment analysis (GSEA) was performed to explore the functions of biomarkers. Furthermore, we also predicted their drug targets, and constructed a competing endogenous RNAs (ceRNA) network and a drug target network. Finally, we verified their mRNA expression using quantitative real-time polymerase chain reaction (qRT-PCR). Results: Total three VV-MRGs, namely Wnt1-inducible signaling pathway protein 2 (WISP2), Cysteine-rich intestinal protein 1 (CRIP1), and Odd-skipped related 1 (OSR1) were identified by VVGs and MRGs overlapping. The area under the curves (AUCs) of the ROC curves for these three VV-MRGs were greater than 0.8. RF was confirmed as the optimal diagnostic model, and WISP2, CRIP1, and OSR1 were regarded as biomarkers. GSEA showed that WISP2, CRIP1, and OSR1 were associated with oxidative phosphorylation, extracellular matrix (ECM), and respiratory system functions. Furthermore, we found that lncRNA MIR17HG can regulate OSR1 by binding to hsa-miR-21-5p and that PAX2 might treat VV by targeting OSR1. Finally, qRT-PCR results showed that the mRNA expression of the three genes was consistent with the results of the datasets. Conclusion: This study identified WISP2, CRIP1, and OSR1 as biomarkers of VV through comprehensive bioinformatics analysis, and preliminary explored the DNA methylation-related molecular mechanism in VV, which might be important for VV diagnosis and exploration of potential molecular mechanisms.

Cysteine-rich intestinal protein 1 enhances the progression of hepatocellular carcinoma via Ras signaling.

The present study aimed to explore the expression and clinical significance of cysteine-rich intestinal protein 1 (CRIP1) mRNA in the serum of patients with hepatocellular carcinoma (HCC). Reverse transcription polymerase chain reaction (RT-PCR) was performed to explore the level of CRIP1 mRNA in the tissues and serum of patients with HCC. Our data showed that the mRNA level of CRIP1 was significantly elevated in the serum and tissues of HCC patients. Moreover, serum CRIP1 mRNA was significantly elevated in HCC patients with larger tumor sizes and higher tumor node metastasis (TNM) stages. Receiver operating characteristic analysis showed that compared with a single marker, the combined detection of alpha-fetoprotein, carcinoembryonic antigen, and CRIP1 had the highest accuracy, sensitivity, and specificity. Further study showed that the overexpression of CRIP1 enhanced the proliferation and migration of HepG2 cells, but the inhibition of CRIP1 decreased the proliferation and migration of HepG2 cells. Microarray assays and KyotoEncyclopedia of Genes and Genomes (KEGG) pathway analysis showed that overexpression of CRIP1 induced the activation of Ras signaling. Co-immunoprecipitation (Co-IP) assays indicated that CRIP1 could interact with Ras. To further evaluate whether CRIP1 interacts with Ras, a specific siRNA targeting Ras was selected. We found that Ras knockdown reduced the activation of Ras/AKT signaling even in HepG2 cells transfected with CRIP1. Moreover, elevated expression of CRIP1 increased the proliferation of HepG2 cells, but such effects could be abolished by silencing Ras. In summary, elevated CRIP1 levels enhanced the progression of CRIP1 via Ras signaling.

Cysteine-Rich Intestinal Protein 1 Served as an Epithelial Ovarian Cancer Marker via Promoting Wnt/β-Catenin-Mediated EMT and Tumour Metastasis.

Objective To explore the expression, functions, and the possible mechanisms of cysteine-rich intestinal protein 1 (CRIP1) in epithelial ovarian cancer. Methods Using open microarray datasets from The Cancer Genome Atlas (TCGA), we identified the tumorigenic genes in ovarian cancer. Then, we detected CRIP1 expression in 26 pairs of epithelial ovarian cancer tissue samples by immunohistochemistry (IHC) and performed a correlation analysis between CRIP1 and the clinicopathological features. In addition, epithelial ovarian cancer cell lines A2780 and OVCAR3 were used to examine CRIP1 expression by western blot and qRT-PCR. Various cell function experiments related to tumorigenesis were performed including the CCK8 assay, EdU, Annexin V-FITC/PI apoptosis assay, wound healing, and Transwell assay. In addition, the expression of epithelial-mesenchymal transition (EMT) markers was detected by western blot to illustrate the relationship between CRIP1 and EMT. Furthermore, KEGG pathway enrichment analysis and western blot were conducted to reveal the signaling pathways in which CRIP1 is involved in ovarian cancer pathogenesis. Results CRIP1 was identified as an oncogene from the TCGA database. The IHC score demonstrated that the CRIP1 protein was expressed at a higher level in tumours than in tumour-adjacent tissues and was associated with a higher pathological stage, grade, and positive lymphatic metastasis. In cell models, CRIP1 was overexpressed in serous epithelial ovarian cancer. Cell function experiments showed that the knockdown of CRIP1 did not significantly affect cell proliferation or apoptosis but could exert an inhibitory effect on cell migration and invasion, and also induce changes in EMT markers. Furthermore, KEGG pathway enrichment analysis and western blot showed that CRIP1 could induce ovarian cancer cell metastasis through activation of the Wnt/β-catenin pathway. Conclusion This study is the first to demonstrate that CRIP1 acts as an oncogene and may promote tumour metastasis by regulating the EMT-related Wnt/β-catenin signaling pathway, suggesting that CRIP1 may be an important biomarker for ovarian cancer metastasis and progression.

CRIP1 cooperates with BRCA2 to drive the nuclear enrichment of RAD51 and to facilitate homologous repair upon DNA damage induced by chemotherapy

Homologous recombination (HR) repair is an important determinant of chemosensitivity. However, the mechanisms underlying HR regulation remain largely unknown. Cysteine-rich intestinal protein 1 (CRIP1) is a member of the LIM/double-zinc finger protein family and is overexpressed and associated with prognosis in several tumor types. However, to date, the functional role of CRIP1 in cancer biology is poorly understood. Here we found that CRIP1 downregulation causes HR repair deficiency with concomitant increase in cell sensitivity to cisplatin, epirubicin, and the poly ADP-ribose polymerase (PARP) inhibitor olaparib in gastric cancer cells. Mechanistically, upon DNA damage, CRIP1 is deubiquitinated and upregulated by activated AKT signaling. CRIP1, in turn, promotes nuclear enrichment of RAD51, which is a prerequisite step for HR commencement, by stabilizing BRCA2 to counteract FBXO5-targeted RAD51 degradation and by binding to the core domain of RAD51 (RAD51184–257) in coordination with BRCA2, to facilitate nuclear export signal masking interactions between BRCA2 and RAD51. Moreover, through mass spectrometry screening, we found that KPNA4 is at least one of the carriers controlling the nucleo-cytoplasmic distribution of the CRIP1–BRCA2–RAD51 complex in response to chemotherapy. Consistent with these findings, RAD51 inhibitors block the CRIP1-mediated HR process, thereby restoring chemotherapy sensitivity of gastric cancer cells with high CRIP1 expression. Analysis of patient specimens revealed an abnormally high level of CRIP1 expression in GC tissues compared to that in the adjacent normal mucosa and a significant negative association between CRIP1 expression and survival time in patient cohorts with different types of solid tumors undergoing genotoxic treatments. In conclusion, our study suggests an essential function of CRIP1 in promoting HR repair and facilitating gastric cancer cell adaptation to genotoxic therapy.

Weighted Gene Coexpression Network Analysis Identifies Cysteine-Rich Intestinal Protein 1 (CRIP1) as a Prognostic Gene Associated with Relapse in Patients with Acute Myeloid Leukemia.

BackgroundAcute myeloid leukemia (AML) is associated with a high relapse rate and poor prognosis. This study aimed to use weighted gene coexpression network analysis (WGCNA) of gene coexpression networks to identify candidate prognostic biomarker genes in patients with AML and to investigate the expression of these genes in the human U937 cell line in vitro.Material/MethodsRNA-seq data were retrieved from the Cancer Genome Atlas (TCGA) and included bone marrow samples and survival data of patients with AML (N=151), patients who did not relapse after treatment (N=119), and patients with relapse (N=40). Differentially expressed genes were identified, WGCNA was used to detect functional modules, and survival analysis was performed. The Cell Counting Kit-8 (CCK-8) assay investigated the proliferation of U937 cells transfected with short hairpin RNAs (shRNAs), shCRIP1, shHIST1H1C, and shHIST1H1E. RNA-seq analysis identified gene expression following CRIP1 knockdown.ResultsEighty-two genes were associated with both relapse and prognosis in patients with AML. There were two prognosis-related gene modules in the coexpression network. In the coexpression network, the histone cluster 1 H1 family member gene, HIST1H1C had the maximum relapse fold change, HIST1H1E had the lowest survival p-value, and the cysteine-rich intestinal protein 1 (CRIP1) gene had the most edge numbers and was significantly associated with poor prognosis (P=0.0165786). RNA-seq data showed that there was a significant difference in gene expression after CRIP1 knockdown in U937 cells.ConclusionsWGCNA of gene coexpression networks identified CRIP1 as a potential prognostic biomarker gene in patients with AML.

Cysteine-rich intestinal protein 1 suppresses apoptosis and chemosensitivity to 5-fluorouracil in colorectal cancer through ubiquitin-mediated Fas degradation

BackgroundCysteine-rich intestinal protein 1 (CRIP1) is highly expressed in human intestine and aberrantly expressed in several types of tumor. However, studies on CRIP1 are limited and its role on tumor development and progression remains controversial and elusive.MethodsImmunohistochemistry was performed to evaluate the expression of CRIP1 in paired normal and colorectal tumor specimens, as well as colorectal cell lines. Functional assays, such as CCK8, TUNEL assay and in vivo tumor growth assay, were used to detect the proliferation, apoptosis and response to 5-FU of CRIP1. Western blot was used to analyze Fas-mediated pathway induced by CRIP1. Rescue experiments were performed to evaluate the essential role of CRIP1 for Fas-mediated apoptosis.ResultsWe demonstrated that CRIP1 is overexpressed in CRC tissues compared with adjacent normal mucosa. CRIP1 could dramatically recover the 5-Fluorouracil (5-FU) inhibited CRC cell proliferation in vitro and stimulate the tumor formation of CRC in vivo, probably through inhibiting CRC cell apoptosis. Moreover, CRIP1 also dramatically recovered the 5-Fluorouracil (5-FU) induced tumor cell apoptosis in vitro. Further study demonstrated that CRIP1 down-regulated the expression of Fas protein and proteins related to Fas-mediated apoptosis. CRIP1 could interact with Fas protein and stimulate its ubiquitination and degradation. In addition, a negative correlation was detected between the expression of CRIP1 and Fas protein in most of the clinical human CRC samples.ConclusionThe current research reveals a vital role of CRIP1 in CRC progression, which provide a novel target for clinical drug resistance of colorectal cancer and undoubtedly contributing to the therapeutic strategies in CRC.

CRIP1 promotes cell migration, invasion and epithelial-mesenchymal transition of cervical cancer by activating the Wnt/β‑catenin signaling pathway

Cervical cancer (CC) is the third most common cancer and the fourth leading cause of malignancy-related mortality in women worldwide. In addition, epithelial–mesenchymal transition (EMT) has been generally studied in tumor metastasis researches in recent years. Cysteine-rich intestinal protein 1 (CRIP1) is differently expressed in human cancer cells. However, the role it plays in CC has not been revealed at present. Preliminary experiments have shown that CRIP1 had a higher expression in CC tissues, compared with adjacent noncancerous tissues. Real-time PCR and western blot were performed to analyze CRIP1 expression in CC cell lines. CRIP1 transient transfection vector and siRNA were constructed. Further analysis revealed the promotion effects of CRIP1 on the cell migration and invasion of CC in vitro (P < 0.01). In addition, western blot was performed to show that CRIP1 mediates EMT by means of EMT marker detection. The expression of CRIP1 and β‑catenin in CC tissues was analyzed by immunohistochemistry (IHC). Interestingly, CRIP1 and β‑catenin were both highly expressed in CC tissues (P < 0.01). Furthermore, CRIP1 increased the protein expression level of c-myc, cyclinD-1 and cytoplasmic β‑catenin, which are indicators for activating the Wnt/β‑catenin signaling pathway. In conclusion, CRIP1 promotes cell migration and invasion, mediates EMT and activates the Wnt/β‑catenin signaling pathway in CC.

Amplified pathogenic actions of angiotensin II in cysteine-rich LIM-only protein 4-negative mouse hearts.

LIM domain proteins have been identified as essential modulators of cardiac biology and pathology; however, it is unclear which role the cysteine-rich LIM-only protein (CRP)4 plays in these processes. In studying CRP4 mutant mice, we found that their hearts developed normally, but lack of CRP4 exaggerated multiple parameters of the cardiac stress response to the neurohormone angiotensin II (Ang II). Aiming to dissect the molecular details, we found a link between CRP4 and the cardioprotective cGMP pathway, as well as a multiprotein complex comprising well-known hypertrophy-associated factors. Significant enrichment of the cysteine-rich intestinal protein (CRIP)1 in murine hearts lacking CRP4, as well as severe cardiac defects and premature death of CRIP1 and CRP4 morphant zebrafish embryos, further support the notion that depleting CRP4 is incompatible with a proper cardiac development and function. Together, amplified Ang II signaling identified CRP4 as a novel antiremodeling factor regulated, at least to some extent, by cardiac cGMP.-Straubinger, J., Boldt, K., Kuret, A., Deng, L., Krattenmacher, D., Bork, N., Desch, M., Feil, R., Feil, S., Nemer, M., Ueffing, M., Ruth, P., Just, S., Lukowski, R. Amplified pathogenic actions of angiotensin II in cysteine-rich LIM-only protein 4 negative mouse hearts.

Cysteine-Rich Intestinal Protein 1 Silencing Inhibits Migration and Invasion in Human Colorectal Cancer

Background/Aims: Cysteine-rich intestinal protein 1 (CRIP1), a member of the LIM/double zinc finger protein family, is abnormally expressed in several tumour types. However, few data are available on the role of CRIP1 in cancer. In the present study, we aimed to investigate the expression profile and functions of CRIP1 in colorectal cancer. Methods: To examine the protein expression level of CRIP1, immunohistochemistry (IHC) was performed on 56 pairs of colon cancer tissue samples. Western blotting was performed to investigate CRIP1 protein expression in four colon cancer cell lines. The endogenous expression of CRIP1 was suppressed using short interfering RNAs (siRNAs). Cell proliferation assays were used to determine whether CRIP1 silencing affected cell proliferation. Flow cytometry analysis was used to detect cell apoptosis. The effects of silencing CRIP1 on cell migration and invasion was detected using the transwell and wound-healing assays. Results: IHC analysis showed that protein level of CRIP1 was significantly higher in tumour tissue samples than in paired non-tumour tissue samples and that the CRIP1 level was higher in metastatic tissue samples than in non-metastatic tissue samples. In addition, protein levels of CRIP1 were higher in highly metastatic colon cancer cell lines than in colon cancer cell lines with low metastasis. Further, CRIP1 silencing had no effect on cell proliferation or apoptosis in SW620 and HT29 cells. CRIP1 silencing suppressed cell migration and invasion obviously in SW620 and HT29 cells. Conclusion: The present study provides new evidence that abnormal expression of CRIP1 might be related to the degree of metastasis in colorectal cancer and that CRIP1 silencing could effectively inhibit migration and invasion during colorectal cancer development. These findings might aid the development of a biomarker for colon cancer prognosis and metastasis, and thus help to treat this common type of cancer.

The Impact of Cysteine-Rich Intestinal Protein 1 (CRIP1) on Thyroid Carcinoma

Background/Aims: CRIP1 (cysteine-rich intestinal protein 1) has been found in several tumor types; however, its prognostic impact and role in cellular processes, particularly in thyroid carcinoma, are still unclear. Methods: To elucidate the prognostic impact of CRIP1, we analyzed tissues from 58 primary invasive thyroid carcinomas using immunohistochemistry. Western blotting was performed to investigate CRIP1 protein expression in the thyrocyte cell line Nthy-ori 3-1 and four different thyroid carcinoma cell lines, K1, TPC-1, TT, and SW579. Endogenous expression of CRIP1 was suppressed using a siRNA (si-CRIP1). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to investigate cell viability. Flow cytometric analysis was used to detect cell cycle progression and cell apoptosis. The effects of silencing CRIP1 on cell migration and invasion were detected using the transwell assay. Results: The immunohistochemistry results showed that CRIP1 was overexpressed in thyroid carcinoma. CRIP1 expression was associated with tumor size, TNM stage, and lymphatic metastasis, but not with age, gender, and tumor location. In addition, the expression of CRIP1 in K1, TPC-1, TT, and SW529 cells was higher than that in the Nthy-ori 3-1 cells. The highest expression was observed in the SW579 and TT cells. Furthermore, silencing CRIP1 inhibited the proliferation, migration, and invasion of thyroid carcinoma cell lines SW579 and TT. We also found that silencing CRIP1 induced G1 arrest and apoptosis of thyroid carcinoma cell lines SW579 and TT. Conclusion: In conclusion, CRIP1 acts as an oncogene in the cell proliferation, migration, and invasion processes of thyroid carcinoma. CRIP1 may serve well as an independent prognostic marker with significant predictive power for use in thyroid carcinoma therapy.

CRIP1, a novel immune-related protein, activated by Enterococcus faecalis in porcine gastrointestinal epithelial cells

Cysteine-rich intestinal protein 1 (CRIP1) is an important transcriptional regulation factor during the tumor development. Although it was largely studied in the human or mouse, no report has provided functional evidence for it in the swine. To date, the real sequence of porcine CRIP1 (poCRIP1) was also still unknown. In this study, clear characteristics for the poCRIP1 were represented. A 552bp poCRIP1 cDNA was obtained from porcine brain tissue using real time reverse transcriptase PCR. The poCRIP1 showed 89% and 93% homologous with human and cattle, respectively. And it also contained one conserved domain, LIM-CRIP domain. Meanwhile, the genomic structure and promoter map was done and several conserved transcriptional regulatory sites were also predicted in this study. The expression pattern of poCRIP1 indicated that poCRIP1 is expressed in mucosal tissue. An infection experiment about the gut was designed to analyze whether or not poCRIP1 was functional in gut immunity, and an interesting result was that poCRIP1 was only activated by an opportunistic pathogen, Enterococcus faecalis FA2-2. It was the first report to identify the full-length sequence of poCRIP1 gene, represent a clear characteristic and immunologic role of CRIP1 in domestic animal until now.

Facilitation of Endosomal Recycling by an IRG Protein Homolog Maintains Apical Tubule Structure in Caenorhabditis elegans.

Determination of luminal diameter is critical to the function of small single-celled tubes. A series of EXC proteins, including EXC-1, prevent swelling of the tubular excretory canals in Caenorhabditis elegans In this study, cloning of exc-1 reveals it to encode a homolog of mammalian IRG proteins, which play roles in immune response and autophagy and are associated with Crohn's disease. Mutants in exc-1 accumulate early endosomes, lack recycling endosomes, and exhibit abnormal apical cytoskeletal structure in regions of enlarged tubules. EXC-1 interacts genetically with two other EXC proteins that also affect endosomal trafficking. In yeast two-hybrid assays, wild-type and putative constitutively active EXC-1 binds to the LIM-domain protein EXC-9, whose homolog, cysteine-rich intestinal protein, is enriched in mammalian intestine. These results suggest a model for IRG function in forming and maintaining apical tubule structure via regulation of endosomal recycling.

MafG, A Novel Target of FXR that Regulates Bile Acid Homeostasis

Bile acids, the major products of hepatic cholesterol catabolism, are indispensable for lipid absorption and cholesterol metabolism. Systemic bile acid metabolism is tightly regulated by various nuclear receptors, including farnesoid X receptor (FXR; Nat Rev Gastroenterol Hepatol 2014;11:55–67). In humans, approximately 500 mg of cholesterol are converted into bile acids every day via the classical pathway initiated by CYP7A1 or an alternative pathway through CYP7B1 (Nat Rev Drug Discov 2008;7:678–693). CYP8B1 is responsible for cholic acid synthesis (J Clin Invest 2002;110:1191–1200). FXR signaling regulates bile acid synthetic pathways by repressing both Cyp7a1 and Cyp8b1 expression. FXR-mediated small heterodimer partner (Shp) induction is a mechanism of the repression of Cyp7a1 expression. However, bile acid synthetic pathways are also regulated by SHP-independent mechanisms. In a recent article published in Cell Metabolism, de Aguiar Vallim et al discovered a novel FXR-regulated transcriptional repressor, MafG (V-Maf avian musculoaponeurotic fibrosarcoma oncogene homolog G) as an important regulator of negative feedback mechanism of bile acids. MafG belongs to small MAF proteins, which is a bidirectional transcriptional regulator. On 1 hand, MafG interacts with transcription factors Nrf2 and HIF1α to increase their transcriptional activity (Biochim Biophys Acta 2008; 1783:1847–1856; FEBS Lett 2008;582:2357–2364). On the other hand, MafG binds to DNA as a homodimer (or sometimes as a heterodimer), which leads to transcriptional repression owing to a lack of transactivation domain (Mol Cell Biol 2006;26:4652–4663). To find the repression mechanism of bile acid synthesis genes by FXR, de Aguiar Vallim et al focused on transcriptional repressors, such as MafG. The ChIP-seq analysis of hepatic FXR from 2 different datasets determined four putative transcriptional repressor genes expressed in the liver MafG, cysteine-rich intestinal protein 2 (Crips2), zinc finger protein 385a (Zfp385a), and Shp. In vivo overexpression of MafG, introduced by injection of adenoviral vector, repressed the expression of Cyp8b1, but not Cyp7a1, in the liver. Crip2 or Zfp385a overexpression did not change either Cyp7a1 or Cyp8b1 expression. Interestingly, MafG overexpression changed the composition of bile acid pool, but not the pool size. The analysis of the hepatic gene profile showed the significant reductions in the expression of bile acid synthesis genes including Cyp7b1 and Cyp27a1 by MafG overexpression. In contrast, the loss-of-gene studies using antisense oligonucleotides or in MafG heterozygous mice showed increased expression of bile acid synthesis genes including Cyp8b1, Cyp7b1, and Cyp27a1, but not Cyp7a1. This confirms that MafG is a repressor of cholic acid synthesis as well as a key regulator of bile acid metabolism. Then, the study investigated to identify MafG binding sites (MAREs) in bile acid synthetic genes through MafG ChIP-seq analysis. The ChIP-seq analysis identified MAREs at loci for multiple bile acid synthetic genes, including Cyp8b1, Cyp27a1, Cyp7b1, Acox2, Akr1d1, Akr1c14, Ntcp, Hsd17b4, and Scp2, but not Cyp7a1. Taken together, the present study demonstrates that FXR signaling regulates bile acid synthesis gene expression through induction of a transcriptional repressor MafG, a novel FXR target gene. MafG binds to MAREs on the promoter and/or intronic regions of multiple bile acid synthetic genes and suppresses their transcription, thereby regulating the bile acid synthesis.

The involvement of cysteine-rich intestinal protein in early development and innate immunity of Asiatic hard clam, Meretrix meretrix

Cysteine-rich intestinal protein (CRIP), a Zn2+-binding protein, contains a single copy of the highly conserved double-zinc-finger structure known as the LIM (lin-11-isl-1-mec-3) motif. In this paper, a cDNA encoding MmCRIP was isolated from the Asiatic hard clam Meretrix meretrix. The full-length cDNA of MmCRIP consists of a 237-bp open reading frame that encodes a polypeptide of 78 amino acids with a predicted molecular weight (MW) of 8635.8 Da and theoretical isoelectric point (pI) of 9.01. Bioinformatics analysis showed that it belonged to a new member of the CRIP subfamily. Relationship analysis revealed that MmCRIP has high-levels of sequence similarity to many CRIPs reported in other animals, particularly in invertebrates. Real-time PCR analysis showed that the highest level of MmCRIP expression was in hemocyte tissue and at pediveligers stage. To investigate immune function, mature clams were challenged with Aeromonas hydrophila. During A. hydrophila infection, up-regulation of MmCRIP transcript in clam's hemocyte, gill and hepatopancreas was detected. DsRNAi (double-strand RNA interference) approach was employed to study the function of MmCRIP and the data showed that inactivation of the MmCRIP gene blocked larvae development and caused mass mortalities. The probable roles of MmCRIP in clam early development and innate immunity are presented for the first time.

Combining Peptide and DNA for Protein Assay: CRIP1 Detection for Breast Cancer Staging

In this work, a novel method for a protein assay is proposed which uses the specific protein-binding peptide of the target protein and sequence-specific DNA to interact with the target as the capture and detection probe, respectively. Meanwhile, since the DNA sequence can be coupled with gold nanoparticles to amplify the signal readout, a sensitive and easily operated method for protein assay is developed. We have also employed a transcription factor named as cysteine-rich intestinal protein 1 (CRIP1), which has been identified as an ideal biomarker for staging of breast cancer, as the model protein for this study. With the proposed method, CRIP1 can be determined in a linear range from 1.25 to 10.13 ng/mL, with a detection limit of 1.25 ng/mL. Furthermore, the proposed method can be directly used to assay CRIP1 in tissue samples. Owing to its desirable sensitivity, excellent reproducibility, and high selectivity, the proposed method may hold great potential in clinical practice in the future.