Kindlin-2, a member of the Kindlin family focal adhesion proteins, plays an important role in cardiac development. It is known that defects in the Z-disc proteins lead to hypertrophic cardiomyopathy(HCM) or dilated cardiomyopathy(DCM). Our previous investigation showed that Kindlin-2 is mainly localized at the Z-disc and depletion of Kindlin-2 disrupts the structure of the Z-Disc. Here, we reported that depletion of Kindlin-2 leads to the disordered myocardial fibers, fractured and vacuolar degeneration in myocardial fibers. Interestingly, depletion of Kindlin-2 in mice induced cardiac myocyte hypertrophy and increased the heart weight. Furthermore, decreased expression of Kindlin-2 led to cardiac dysfunction and also markedly impairs systolic function. Our data indicated that Kindlin-2 not only maintains the cardiac structure but also is required for cardiac function.
Large tumor suppressor 1(LATS1)is the key kinase controlling activation of Hippo signalling pathway.Post-translational modifications of LATS1 modulate its kinase activity.However,detailed mechanism underlying LATS1 stability and activation remains elusive.Here we report that LATS1 is acetylated by acetyltransferase CBP at K751 and is deacetylated by deacetylases SIRT3 and SIRT4.Acetylation at K751 stabilized LATS1 by decreasing LATS1 ubiquitination and inhibited LATS1 activation by reducing its phosphorylation.Mechanistically,LATS1 acetylation resulted in inhibition of YAP phosphorylation and degradation,leading to increased YAP nucleus translocation and promoted target gene expression.Functionally,LATS1-K751 Q,the acetylation mimic mutant potentiated lung cancer cell migration,invasion and tumor growth,whereas LATS1-K751 R,the acetylation deficient mutant inhibited these functions.Taken together,we demonstrated a previously unidentified post-translational modification of LATS1 that converts LATS1 from a tumor suppressor to a tumor promoter by suppression of Hippo signalling through acetylation of LATS1.
Mutations of integrin-interacting protein Kindlin-1 cause Kindler syndrome and deregulation of Kindlin-1 is implicated in human cancers. The Kindlin-1-related diseases are confined in limited tissue types. However, Kindlin-1 tissue distribution and the dogma that governs Kindlin-1 expression in normal human body are elusive. This study examined Kindlin-1 expression in normal human adult organs, human and mouse embryonic organs by immunohistochemical analyses. We identified a general principle that the level of Kindlin-1 expression in tissues is tightly correlated with the corresponding germ layers from which these tissues originate. We compared the expression of Kindlin-1 with Kindlin-2 and found that Kindlin-1 is highly expressed in epithelial tissues derived from ectoderm and endoderm, whereas Kindlin-2 is mainly expressed in mesoderm-derived tissues. Likewise, Kindlin-1 was also found highly expressed in endoderm/ectoderm-derived tissues in human and mouse embryos. Our findings indicate that Kindlin-1 may play an importance role in the development of endoderm/ectoderm related tissues.
Kindlin-2, an integrin-interacting protein, regulates breast cancer progression. However, currently, no animal model to study the role of Kindlin-2 in the carcinogenesis of mammary gland is available. We established a Kindlin-2 transgenic mouse model using a mammary gland-specific promoter, mammary tumor virus(MMTV) long terminal repeat(LTR). Kindlin-2 was overexpressed in the epithelial cells of the transgenic mice. The mammary gland ductal trees were found to grow faster in MMTV-Kindlin-2 transgenic mice than in control mice during puberty. Kindlin-2 promoted mammary gland growth as indicated by more numerous duct branches and larger lumens, and more alveoli were formed in the mammary glands during pregnancy under Kindlin-2 overexpression. Importantly, mammary gland-specific expression of Kindlin-2 induced tumor formation at the age of 55 weeks on average. Additionally, the levels of estrogen receptor and progesterone receptor were decreased, whereas human epidermal growth factor receptor 2 and β-catenin were upregulated in the Kindlin-2-induced mammary tumors. These findings demonstrated that Kindlin-2 induces mammary tumor formation via activation of the Wnt signaling pathway.
LGR6 is a member of the G protein-coupled receptor family that plays a tumor-suppressive role in colon cancer. However, the relationship between LGR6 expression in patients and clinicopathological factors remains unclear. This study aimed to clarify whether the expression level of LGR6 is correlated with colon adenocarcinoma progression. Immunohistochemistry was used to detect LGR6 expression in colon adenoma tissues (n = 21), colon adenocarcinoma tissues (n = 156), and adjacent normal tissues (n = 124). The expression levels of LGR6 in colon adenoma and adenocarcinoma were significantly higher than those in normal colon epithelial tissues (P < 0.001). Low LGR6 expression predicted a short overall survival in patients with colon adenocarcinoma (log-rank test, P = 0.016). Univariate and multivariate survival analyses showed that, in addition to N and M classification, LGR6 expression served as an independent prognostic factor. Thus, low expression of LGR6 can be used as an independent prognostic parameter in patients with colon adenocarcinoma.
Esophageal cancer （EC） is one of the most lethal malignancies in China, but the etiology and risk factors remain unclear. The integrin-interacting proteins Kindlin-1 and Kindlin-2 are focal adhesion molecules that activate transmembrane receptor integrins and regulate tumor cell growth, invasion, and metastasis. Here, we report that Kindlin-1 and Kindlin-2 are differentially expressed among Chinese EC patients. For this, Kindlin-1 and Kindlin-2 expression was evaluated in 220 EC patients by immunohistochemistry （IHC） and found to be correlated with the EC progression, along with a variety of epidemiologic parameters, including smoking, family EC history, and EC invasion status. Moreover, data downloaded from the Oncomine database revealed that both Kindlin- 1 and Kindlin-2 were upregulated in ECs compared with normal esophageal tissues; although Kindlin-1 was highly expressed in well-differentiated tumors, whereas Kindlin-2 was more prevalent in poorly differentiated tumors. Collectively, these data suggest that Kindlin-1 may inhibit, while Kindlin-2 may promote, EC progression. This study, for the first time, linked the expression of Kindlin-1 and Kindlin-2 with EC family genetic background and living habits, which may help further our understanding of the various causes of EC.
Basal-like breast cancer with a luminal progenitor gene expression profile is an aggressive subtype of breast cancer with a poorer prognosis compared with other subtypes.However,genes that specifically promote basal-like breast cancer development remain largely unknown.Here,we report that a novel gene C1orf106 plays an important role in maintaining the feature of basal-like/luminal progenitors.C1orf106 is frequently amplified and overexpressed in basal-like breast cancer and is associated with a poor outcome in patients.In human TCGA database,C1orf106 expression was correlated with upregulation of ELF5 and downregulation of GATA3,two transcription factors that regulate mammary gland stem cell fate.Enhanced expression of C1orf106 promotes tumor progression and expression of basal-like/luminal progenitor marker ELF5;depletion of C1orf106 suppresses tumorigenesis and expression of basal-like/luminal progenitor marker GATA3.These findings suggest that C1orf106 maintains the basal-like/luminal progenitor character through balancing the expression of ELF5 and GATA3.Taken together,we demonstrated that C1orf106 is an important regulator for basal-like/luminal progenitors and targeting C1orf106 is of therapeutic value for breast cancer.
