ADAMTS18 deficiency associates extracellular matrix dysfunction with a higher risk of HER2-positive mammary tumorigenesis and metastasis.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2)-positive breast cancer accounts for about 20% of all breast cancer cases and is correlated with a high relapse rate and poor prognosis. ADAMTS18 is proposed as an important functional tumor suppressor gene involved in multiple malignancies, including breast cancer. It functions as an extracellular matrix (ECM) modifier. However, it remains unclear whether ADAMTS18 affects mammary tumorigenesis and malignant progression through its essential ECM regulatory function. METHODS: To elucidate the role of ADAMTS18 in HER2-positive mammary tumorigenesis and metastasis in vivo, we compared the incidence of mammary tumor and metastasis between Adamts18-knockout (MMTV)-Her2/ErbB2/Neu+ transgenic mice (i.e., Her2t/w/Adamts18-/-) and Adamts18-wildtype (MMTV)-Her2/ErbB2/Neu+ transgenic mice (i.e., Her2t/w/Adamts18+/+). The underlying mechanisms by which ADAMTS18 regulates HER2-positive tumorigenesis and metastasis were investigated by pathology, cell culture, Western blot and immunochemistry. RESULTS: Adamts18 mRNA is mainly expressed in myoepithelial cells of the mammary duct. ADAMTS18 deficiency leads to a significantly increased incidence of mammary tumors and metastasis, as well as mammary hyperplasia in mice, over 30 months of observation. The proliferation, migration and invasion capacities of primary Her2t/w/Adamts18-/- mammary tumor cells are significantly higher than those of primary Her2t/w/Adamts18+/+ mammary tumor cells in vitro. At 30 months of age, the expression levels of laminin (LNα5), fibronectin (FN) and type I collagen (ColI) in the mammary glands of Her2t/w/Adamts18-/- mice are significantly increased, and the activities of integrin-mediated PI3K/AKT, ERK and JNK signaling pathways are enhanced. CONCLUSIONS: ADAMTS18 deficiency leads to alterations in mammary ECM components (e.g., LNα5, FN, ColI), which are associated with a higher risk of HER2-positive mammary tumorigenesis and metastasis.

ADAMTS18 regulates early branching morphogenesis of lacrimal gland and has a significant association with the risk of dry eye in mice.

ADAMTS18 is an orphan member of the ADAMTS family of metalloproteinase. ADAMTS18 mutation has been linked to developmental eye disorders, such as retinal dystrophies and ectopia lentis. Here, we report a new function of ADAMTS18 in modulating the lacrimal gland (LG) branching morphogenesis, and an association with dry eye in mice. Adamts18 mRNA was found to be enriched in the epithelium of branching tips of embryonic (E) LG, but its expression was barely detectable after 2 weeks of birth. Histological analyses of E16.5-E17.5 LG showed that ADAMTS18 deficiency resulted in a significant reduction of epithelial branching in embryonic LG. In vitro culture of E15.5 LG explants showed that the numbers of epithelial buds and branches in Adamts18 knockout (Adamts18-/-) LGs were significantly decreased when compared to those of wild type (Adamts18+/+) LGs after 0 h, 24 h, and 48 h of culture. Increased fibronectin deposition was detected in LG mesenchyme of E16.5 Adamts18-/- mice. At 14 months of age, Adamts18-/- mice manifested multiple LG pathological changes, including acinar atrophy and irregular duct ectasis with periductal fibrosis. The tear volume was significantly decreased in Adamts18-/- mice at 4 months of age, which corresponds to early adulthood in humans.

ADAMTS18 deficiency leads to preputial gland hypoplasia and fibrosis in male mice.

ADAMTSs (A disintegrin and metalloproteinase with thrombospondin motifs) are a family of 19 secreted zinc metalloproteinases that play a major role in the assembly and degradation of the extracellular matrix (ECM) during development, morphogenesis, tissue repair, and remodeling. ADAMTS18 is a poorly characterized member of the ADAMTS family. Previously, ADAMTS18 was found to participate in the development of female reproductive tract in mice. However, whether ADAMTS18 also plays a role in the development of male reproductive system remains unclear. In this study, Adamts18 mRNA was found to be highly expressed in the basal cells of the developing preputial gland. Male Adamts18 knockout (Adamts18-/-) mice exhibit abnormal preputial gland morphogenesis, including reduced size and sharp outline. Histological analyses of preputial gland from 2-week-old male Adamts18-/- mice showed significant atrophy of the whole gland. Preputial glands from 7 months and older Adamts18-/- mice appeared macroscopic swelling on their surface. Histologically, preputial gland swelling is characterized by tissue fibrosis and thicker keratinized squamous cell layer. Preputial gland lesions in age-matched male Adamts18+/+ mice were barely detected. ADAMTS18 deficiency does not lead to significant changes in morphogenesis of prostate and testis in male mice. These results indicate that ADAMTS18 is required for normal morphogenesis and homeostasis of the preputial gland in male mice.

ADAMTS18 regulates vaginal opening through influencing the fusion of Mullerian duct and apoptosis of vaginal epithelial cells in mice.

The ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin Motifs) enzymes are secreted metalloproteinases with major roles in development, morphogenesis, and tissue repair via the assembly and degradation of extracellular matrix (ECM). In this study, we investigated the role of ADAMTS18 in the development of the reproductive tract in female mice by phenotyping Adamts18 knockout (Adamts18-/-) mice. The results showed that Adamst18 mRNAs were abundantly expressed in vaginal epithelial cells and muscularis cells of the developing vagina. At the time of vaginal opening (5 weeks of age), about 41 % of Adamts18-/- females showed enlarged protrusions in the upper and middle parts of the vagina, reduced vaginal length, and simultaneously exhibited vaginal atresia. 6% Adamts18-/- females exhibited vaginal septum. Histological analyses revealed that the paired Mullerian ducts in ∼33 % female Adamts18-/- embryos failed to fuse at embryonic day 15.5 (E15.5) resulting in the formation of two vaginal cavities. Results of TUNEL assay and immunohistochemistry for caspase-3 showed that the number of apoptotic cells in the terminal portion of the vagina of 5-week-old Adamts18-/- females with vaginal atresia was significantly decreased. Adamts18-/- females also showed a significant decrease in serum estradiol E2 compared to age-matched Adamts18+/+ females. Results of qRT-PCR showed that the expression level of the anti-apoptosis gene Bcl-2 was significantly increased and that of the apoptosis-related gene Epha1 was decreased in the vagina of 5-week-old Adamts18-/- females. These results suggest that ADAMTS18 regulates vaginal opening through influencing the fusion of Mullerian ducts and apoptosis of vaginal cells in mice.

Adamts18 modulates the development of the aortic arch and common carotid artery.

Members of a disintegrin and metalloproteinases with thrombospondin motif (ADAMTS) family have been implicated in various vascular diseases. However, their functional roles in early embryonic vascular development are unknown. In this study, we showed that Adamts18 is highly expressed at E11.5-E14.5 in cells surrounding the embryonic aortic arch (AOAR) and the common carotid artery (CCA) during branchial arch artery development in mice. Adamts18 deficiency was found to cause abnormal development of AOAR, CCA, and the third and fourth branchial arch appendages, leading to hypoplastic carotid body, thymus, and variation of middle cerebral artery. Adamts18 was shown to affect the accumulation of extracellular matrix (ECM) components, in particular fibronectin (Fn), around AOAR and CCA. As a result of increased Fn accumulation, the Notch3 signaling pathway was activated to promote the differentiation of cranial neural crest cells (CNCCs) to vascular smooth muscle cells. These data indicate that Adamts18-mediated ECM homeostasis is crucial for the differentiation of CNCCs.

ADAMTS18 Deficiency Leads to Pulmonary Hypoplasia and Bronchial Microfibril Accumulation.

ADAMTSs (a disintegrin and metalloproteinase with thrombospondin motifs) are secreted metalloproteinases that play a major role in the assembly and degradation of the extracellular matrix (ECM). In this study, we show that ADAMTS18, produced by the epithelial cells of distal airways and mesenchymal cells in lung apex at early embryonic stages, serves as a morphogen in lung development. ADAMTS18 deficiency leads to reduced number and length of bronchi, tipped lung apexes, and dilated alveoli. These developmental defects worsen lipopolysaccharide-induced acute lung injury and bleomycin-induced lung fibrosis in adult Adamts18-deficient mice. ADAMTS18 deficiency also causes increased levels of fibrillin1 and fibrillin2, bronchial microfibril accumulation, decreased focal adhesion kinase signaling, and disruption of F-actin organization. Our findings indicate that ECM homeostasis mediated by ADAMTS18 is pivotal in airway branching morphogenesis.

CMT2Q-causing mutation in the Dhtkd1 gene lead to sensory defects, mitochondrial accumulation and altered metabolism in a knock-in mouse model.

Charcot-Marie-Tooth disease (CMT) is a group of inherited neurological disorders of the peripheral nervous system. CMT is subdivided into two main types: a demyelinating form, known as CMT1, and an axonal form, known as CMT2. Nearly 30 genes have been identified as a cause of CMT2. One of these is the 'dehydrogenase E1 and transketolase domain containing 1' (DHTKD1) gene. We previously demonstrated that a nonsense mutation [c.1455 T > G (p.Y485*)] in exon 8 of DHTKD1 is one of the disease-causing mutations in CMT2Q (MIM 615025). The aim of the current study was to investigate whether human disease-causing mutations in the Dhtkd1 gene cause CMT2Q phenotypes in a mouse model in order to investigate the physiological function and pathogenic mechanisms associated with mutations in the Dhtkd1 gene in vivo. Therefore, we generated a knock-in mouse model with the Dhtkd1Y486* point mutation. We observed that the Dhtkd1 expression level in sciatic nerve of knock-in mice was significantly lower than in wild-type mice. Moreover, a histopathological phenotype was observed, reminiscent of a peripheral neuropathy, including reduced large axon diameter and abnormal myelination in peripheral nerves. The knock-in mice also displayed clear sensory defects, while no abnormalities in the motor performance were observed. In addition, accumulation of mitochondria and an elevated energy metabolic state was observed in the knock-in mice. Taken together, our study indicates that the Dhtkd1Y486* knock-in mice partially recapitulate the clinical phenotypes of CMT2Q patients and we hypothesize that there might be a compensatory effect from the elevated metabolic state in the knock-in mice that enables them to maintain their normal locomotor function.

Adamts18 deficiency in zebrafish embryo causes defective trunk angiogenesis and caudal vein plexus formation.

ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin type I motifs) enzymes play an important role in various morphogenesis processes. To determine the functions of Adamts18 in the early stages of organogenesis, we created Adamts18 deficient zebrafish using morpholino antisense oligonucleotides (MO) to generate exon 3 skipped adamts18 mRNA transcripts. Results showed that Adamts18 deficiency in zebrafish embryos caused developmental defects, including expanded brain ventricle and hindbrain edema, eye defects, and accumulation of blood in the caudal vein. Adamts18 deficiency also led to impaired trunk angiogenesis and formation of the caudal vein plexus (CVP). Consequently, Adamts18 deficient zebrafish embryos exhibited incomplete formation of intersegment vessels (ISVs), disruption of the honeycomb structure of CVP, and reduced CVP area and loop number. Furthermore, Adamts18 deficiency resulted in impaired blood circulation in major trunk, caudal vein (CV), and common cardinal vein (CCV). These aberrant vascular phenotypes in mutant zebrafish embryos were shown to be associated with a decreased expression of multiple angiogenesis-related signaling genes, including slit/robo, dll4/Notch, cox2, and fgfr. These findings indicate the critical role of Adamts18 in the early stages of vascular network development.

ADAMTS18 Deficiency Affects Neuronal Morphogenesis and Reduces the Levels of Depression-like Behaviors in Mice.

The ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) enzymes are secreted, multi-domain matrix-associated zinc metalloendopeptidases that modify extracellular matrix components and play crucial roles in development and numerous diseases. ADAMTS18 is a member of the ADAMTS family, and genome-wide association studies made an initial association of ADAMTS18 with white matter integrity in healthy people of 72-74 years old. However, the potential roles of ADAMTS18 in central nervous system remain unclear. In this study, we showed that Adamts18 mRNA is highly abundant in developing brains, especially in the cerebellum granular cell layer and the hippocampus dentate gyrus (DG) granular cell layer. Adamts18 knockout (KO) mice displayed higher dendritic branching complexity and spine density on hippocampal DG granular cells. Behavioral tests showed that Adamts18 KO mice had reduced levels of depression-like behaviors compared to their wild-type (WT) littermates. The increased neurite formation could be attributed in part to reduced phosphorylation levels of the collapsin response mediator protein-2 (CRMP2) due to activation of the laminin/PI3K/AKT/GSK-3ß signaling pathway. Our findings revealed a critical role of ADAMTS18 in neuronal morphogenesis and emotional control in mice.

Adamts18 deficiency increases arterial thrombus formation associated with vascular defects in mice.

ADAMTS18 is a member of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) that are known for their crucial role in development, angiogenesis, inflammation and coagulation. It was previously reported that ADAMTS18 cleaved by thrombin induced platelet fragmentation, through which thrombus were dissolved. However, it remains unclear whether this represents a dominant physiologic mechanism controlling thrombus growth in vivo. Here, we used an established Adamts18 knockout (KO) mouse model to determine its function in thrombus formation. ADAMTS18 deficiency accelerated FeCl3-induced carotid artery thrombosis and aggravated postischemic cerebral infarction in mice. However, this accelerated thrombus phenotype in Adamts18 KO mice was not due to the lack of ADAMTS18-mediated-platelet fragmentation. Moreover, Adamts18 deficiency exerted little effects on mouse platelet functions. The underlying molecular mechanisms could be attributed in part to the abnormal vascular remodeling, including deficiency of carotid body (glomus) and aberrant carotid basal lamina. These results indicate a novel function of ADAMTS18 in vascular remodeling and associated thrombus formation.

A Disintegrin and Metalloproteinase with Thrombospondin Motifs 18 Deficiency Leads to Visceral Adiposity and Associated Metabolic Syndrome in Mice.

Visceral adiposity is of greater risk than obesity in s.c. adipose tissue for diabetes and cardiovascular disease. Its pathogenesis remains unclear, but it is associated with extracellular matrix (ECM) remodeling. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) are a family of secreted zinc-dependent metalloproteinases that play crucial roles in development and various diseases because of their ECM remodeling activity. ADAMTS18 is an orphan ADAMTS whose function and substrate remain unclear. Herein, we showed that Adamts18 mRNA was abundantly expressed in visceral (gonadal) white adipose tissue (vWAT) during the early stage of development after birth. Adamts18 knockout (KO) mice showed increased body fat percentage and larger adipocyte size in vWAT relative to wild-type littermates. These findings may be partly attributed to ECM remodeling, especially increased expression of laminin 1 and adipokine thrombospondin 1 in vWAT. Attenuated extracellular signal-regulated kinase 1 and 2 activity, along with increased expression of adipocyte-specific transcription factors peroxisome proliferator-activated receptor-γ, CCAAT/enhancer binding protein ß, and marker gene Fabp4, was detected in vWAT of Adamts18 KO mice. Furthermore, Adamts18 KO mice showed early metabolic syndrome, including hyperlipidemia, blood glucose metabolic disorder, and hypertension. ADAMTS18 deficiency promotes atherosclerosis in apolipoprotein E-deficient mice. These results indicate a novel function of ADAMTS18 in vWAT development and associated metabolic disorders.

The development of monoclonal anti-ADAMTS18 antibodies with precise validation of ADAMTS18 post-translational modification status in living organisms.

ADAMTS18 is a member of a secreted Zn-metalloproteinase ADAMTS family, and has been implicated in development, hemostasis, and various malignancies. It has thus far proven difficult to resolve its post-translational modification status, cleaved forms, and splice variants in living organisms due to the lack of specific antibodies available to characterize this enzyme. In this study, we develop six murine monoclonal antibodies (mAbs) against different functional regions of ADAMTS18 using hybridoma technology. These mAbs exhibit cross-recognition between ADAMTS18 and the homology domain of its family members. Using the tissues from Adamts18 knockout (KO) mice, we find that two of these mAbs (N-3 and C-5) precisely identify five significantly attenuated bands located at 180, 135, 95, 72, and 45 kDa. These bands represent the forms of ADAMTS18 that potentially exist in the tissues. These mAbs will provide a useful tool to investigate the ADAMTS18's biologic significance in the tissues.

Adamts18 deficiency promotes colon carcinogenesis by enhancing ß-catenin and p38MAPK/ERK1/2 signaling in the mouse model of AOM/DSS-induced colitis-associated colorectal cancer.

ADAMTS18 is a novel tumor suppressor and is critical to the pathology of human colorectal cancer. However, the underlying mechanism is not clear. Here we generated an Adamts18-deficient mouse strain as an in vivo model to investigate the role of ADAMTS18 in the pathogenesis of colorectal cancer. In AOM/DSS-induced colitis-associated colorectal cancer, the deficiency of Adamts18 in mice resulted in enhanced tumorigenesis and colon inflammation that could be attributed in part to enhanced nuclear translocation of ß-catenin and elevated expression of its downstream target genes, cyclin D1 and c-myc. Moreover, increased p38MAPK and ERK1/2 activities were detected in colon cancer cells from Adamts18-deficient mice. Further studies revealed that ADAMTS18 deficiency reduced intestinal E-cadherin levels in mice, which ultimately led to intestinal barrier dysfunction. These data indicate that Adamts18 deficiency enhances tumorigenesis and intestinal inflammation through elevated Wnt/ß-catenin and p38MAPK/ERK1/2 signaling and promotes colon cancer in this mouse model.

Retinol dehydrogenase 13 deficiency diminishes carbon tetrachloride-induced liver fibrosis in mice.

Retinol dehydrogenase 13 (RDH13) is a mitochondrion-localized member of the short-chain dehydrogenases/reductases (SDRs) superfamily that participates in metabolism of some compounds. Rdh13 mRNA is most highly expressed in mouse liver. Rdh13 deficiency reduces the extent of liver injury and fibrosis, reduces hepatic stellate cell (HSC) activation, attenuates collagen I (II), tissue inhibitor of metalloproteinase 1 (TIMP-1) and transforming growth factor beta 1 (Tgf-ß1) expression. The results indicate an important role of Rdh13 and suggest RDH13 as a possible new therapeutic target for CCl4-induced fibrosis.

Palladin is involved in platelet activation and arterial thrombosis.

The dynamics of actin cytoskeleton have been shown to play a critical role during platelet activation. Palladin is an actin-associated protein, serving as a cytoskeleton scaffold to bundle actin fibers and actin cross linker. The functional role of palladin on platelet activation has not been investigated. Here, we characterized heterozygous palladin knockout (palladin+/-) mice to elucidate the platelet-related functions of palladin. The results showed that palladin was expressed in platelets and moderate palladin deficiency accelerated hemostasis and arterial thrombosis. The aggregation of palladin+/- platelets was increased in response to low levels of thrombin, U46619, and collagen. We also observed enhanced spreading of palladin+/- platelets on immobilized fibrinogen (Fg) and increased rate of clot retraction in platelet-rich plasma (PRP) containing palladin+/- platelets. Furthermore, the activation of the small GTPase Rac1 and Cdc42, which is associated with cytoskeletal dynamics and platelet activation signalings, was increased in the spreading and aggregating palladin+/- platelets compared to that in wild type platelets. Taken together, these findings indicated that palladin is involved in platelet activation and arterial thrombosis, implying a potent role of palladin in pathophysiology of thrombotic diseases.

ADAMTS-18 in the host tissues exerts little effect on breast tumor progress in a murine 4T1 breast cancer model.

BACKGROUND: In this study, we aimed to identify a novel extracellular proteinase ADAMTS-18 that could be a potential tumor suppressor gene. RESULTS: We successfully constructed Adamts-18 knockout mice with BALB / c background. RT-PCR analysis showed syngeneic mammary tumor cell line 4 T1 per se has weakly endogenous ADAMTS-18 expression. Orthotopic inoculation of 4 T1 cells within the mammary fat pad of host mice, we found no significant difference in tumor growth and metastasis between Adamts-18 knockout mice and widetype control. CONCLUSIONS: We did not confirm that ADAMTS-18 in the host tissues is relevant for breast tumor progress in a murine 4 T1 breast cancer model.

Integrin GPIIIa49-57 is the pivotal switch controlling platelet fragmentation.

Unique autologous antibodies (Abs) against platelet integrin GPIIIa49-66 (CAPESIEFPVSEARVLED) have been detected in patients with HIV-1 immune-related thrombocytopenia (HIV-1-ITP), which is capable of inducing complement-independent platelet fragmentation through reactive oxygen species (ROS) release. However, the efficiency of inducing platelet fragmentation is inconsistent among the different patient Abs or similar rabbit polyclonal Abs against the region and the reason remains unclear. In this study, we developed a batch of murine monoclonal antibodies (mAbs) against different locus of GPIIIa49-66 region by hybridoma technology. All these mAbs are capable of binding to human platelets. Among these mAbs, clones 1E7 and 5A10 were identified to target the epitope of GPIIIa49-57 (CAPESIEFP, named P1); clones 1C1 and 1E5 target GPIIIa57-64 (PVSEARVL, named P2), and clones 4D5 and 5F8 target GPIIIa59-66 (SEARVLED, named P3). By incubation of human platelets with these mAbs, the platelet fragmentation induced by mAbs against P1 was 5-6 folds higher than that by the control mAb (6-fold for 5A10 and 5.6-fold for 1E7). However, platelet fragmentation induced by mAbs against P2 (1C1) and P3 (5F8) was only 1.9- and 1.1-fold higher than that by the control mAb, respectively. Thus, our data demonstrate that platelet integrin GPIIIa49-57 is the pivotal switch controlling platelet fragmentation.

Deficiency of BPOZ2 Decreases Liver Fibrosis After Chronic Carbon Tetrachloride Administration in Mice.

Bood POZ containing gene type 2 (BPOZ2), a Broad-Complex, Tramtrack, and Bric a brac domain containing protein, is an adaptor protein for the E3 ubiquitin ligase scaffold protein CUL3. It plays an important role in acute carbon tetrachloride (CCl4)-induced liver injury and regeneration in mice. In this study, we investigated the role of BPOZ2 in the process of liver fibrosis induced by chronic CCl4 treatment. The results indicate that BPOZ2 deficiency decreases sustained activation of hepatic stellate cells, attenuates collagen αI(I) and tissue inhibitor of matrix metalloprotease 1 expression, and decreases liver fibrosis after repeated CCl4 administration. These findings suggest BPOZ2 as a new therapeutic target for the prevention and treatment of hepatic fibrosis in chronic liver disease.

Deletion of Gpr128 results in weight loss and increased intestinal contraction frequency.

AIM: To generate a Gpr128 gene knockout mouse model and to investigate its phenotypes and the biological function of the Gpr128 gene. METHODS: Bacterial artificial chromosome-retrieval methods were used for constructing the targeting vector. Using homologous recombination and microinjection technology, a Gpr128 knockout mouse model on a mixed 129/BL6 background was generated. The mice were genotyped by polymerase chain reaction (PCR) analysis of tail DNA and fed a standard laboratory chow diet. Animals of both sexes were used, and the phenotypes were assessed by histological, biochemical, molecular and physiological analyses. Semi-quantitative reverse transcription-PCR and Northern blotting were used to determine the tissue distribution of Gpr128 mRNA. Beginning at the age of 4 wk, body weights were recorded every 4 wk. Food, feces, blood and organ samples were collected to analyze food consumption, fecal quantity, organ weight and constituents of the blood and plasma. A Trendelenburg preparation was utilized to examine intestinal motility in wild-type (WT) and Gpr128(-/-) mice at the age of 8 and 32 wk. RESULTS: Gpr128 mRNA was highly and exclusively detected in the intestinal tissues. Targeted deletion of Gpr128 in adult mice resulted in reduced body weight gain, and mutant mice exhibited an increased frequency of peristaltic contraction and slow wave potential of the small intestine. The Gpr128(+/+) mice gained more weight on average than the Gpr128(-/-) mice since 24 wk, being 30.81 ± 2.84 g and 25.74 ± 4.50 g, respectively (n = 10, P < 0.01). The frequency of small intestinal peristaltic contraction was increased in Gpr128(-/-) mice. At the age of 8 wk, the frequency of peristalsis with an intraluminal pressure of 3 cmH2O was 6.6 ± 2.3 peristalsis/15 min in Gpr128(-/-) intestine (n = 5) vs 2.6 ± 1.7 peristalsis/15 min in WT intestine (n = 5, P < 0.05). At the age of 32 wk, the frequency of peristaltic contraction with an intraluminal pressure of 2 and 3 cmH2O was 4.6 ± 2.3 and 3.1 ± 0.8 peristalsis/15 min in WT mice (n = 8), whereas in Gpr128(-/-) mice (n = 8) the frequency of contraction was 8.3 ± 3.0 and 7.4 ± 3.1 peristalsis/15 min, respectively (2 cmH2O: P < 0.05 vs WT; 3 cmH2O: P < 0.01 vs WT). The frequency of slow wave potential in Gpr128(-/-) intestine (35.8 ± 4.3, 36.4 ± 4.2 and 37.1 ± 4.8/min with an intraluminal pressure of 1, 2 and 3 cmH2O, n = 8) was also higher than in WT intestine (30.6 ± 4.2, 31.4 ± 3.9 and 31.9 ± 4.5/min, n = 8, P < 0.05). CONCLUSION: We have generated a mouse model with a targeted deletion of Gpr128 and found reduced body weight and increased intestinal contraction frequency in this animal model.

Targeted deletion of Kif18a protects from colitis-associated colorectal (CAC) tumors in mice through impairing Akt phosphorylation.

Kinesins are a superfamily of molecular motors involved in cell division or intracellular transport. They are becoming important targets for chemotherapeutic intervention of cancer due to their crucial role in mitosis. Here, we demonstrate that the kinesin-8 Kif18a is overexpressed in murine CAC and is a crucial promoter during early CAC carcinogenesis. Kif18a-deficient mice are evidently protected from AOM-DSS-induced colon carcinogenesis. Kif18A is responsible for proliferation of colonic tumor cells, while Kif18a ablation in mice promotes cell apoptosis. Mechanistically, Kif18a is responsible for induction of Akt phosphorylation, which is known to be associated with cell survival regulation. In conclusion, Kif18a is critical for colorectal carcinogenesis in the setting of inflammation by mechanisms of increased PI3K-AKT signaling. Inhibition of Kif18A activity may be useful in the prevention or chemotherapeutic intervention of CAC.