Elicitation of metastasis associated protein 2 expression in the phagocytosis by murine testicular Sertoli cells

Melatonin combined with sorafenib synergistically inhibit the invasive ability through targeting metastasis-associated protein 2 expression in human renal cancer cells

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TNF-α/ENO1 signaling facilitates testicular phagocytosis by directly activating Elmo1 gene expression in mouse Sertoli cells

Phagocytic clearance of apoptotic germ cells (GCs), as well as residual bodies (RBs) released from developing spermatids, is critical for Sertoli cells (SCs) to maintain inner environment homeostasis within testis. However, the molecular mechanisms controlling the phagocytosis are ill defined. Here, we identify a new role for alpha-enolase (ENO1), a key enzyme during glycolysis, as a molecule that facilitates testicular phagocytosis via transactivation of the engulfment and cell motility 1 (Elmo1) gene. Using immunohistochesmitry and double-labeling immunofluorescence, ENO1 was observed to be expressed exclusively in the nuclei of SCs and its expression correlated with the completion of Sertoli cell differentiation. By incubating TM4 cells with different pharmacological inhibitors and establishing TM4^Tnfr1-/- cells, we demonstrated that Sertoli cell-specific expression of ENO1 was under a delicate paracrine control from apoptotic GCs. In turn, persistent blockade of ENO1 expression by a validated siRNA protocol resulted in the disturbance of spermatogenesis and impairment of male fertility. Furthermore, using chromatin immunoprecipitation, electrophoretic mobility shift assay and luciferase reporter assay, we showed that in the presence of apoptotic GCs, ENO1 binds to the distal region of the Elmo1 promoter and facilitates transactivation of the Elmo1 gene. In agreement, overexpression of ELMO1 ameliorated ENO1 deficiency-induced impairment of phagocytosis in TM4 cells. These data reveal a novel role for Sertoli cell-specific expression of ENO1 in regulating phagocytosis in testis, identify TNF-α and ELMO1 as critical upstream and downstream factors in mediating ENO1 action, and have important implications for understanding paracrine control of Sertoli cell function by adjacent GCs.

Unexpected requirement for a binding partner of the syntaxin family in phagocytosis by murine testicular Sertoli cells

Testicular phagocytosis by Sertoli cells (SCs) plays an essential role in the efficient clearance of apoptotic spermatogenic cells under both physiological and pathological conditions. However, the molecular mechanism underlying this unique process is poorly understood. Herein, we report for the first time that α-taxilin protein (TXLNA), a binding partner of the syntaxin family that functions as a central player in the intracellular vesicle traffic, was dominantly expressed in SCs. Induction of apoptosis in murine meiotic spermatocytes and haploid spermatids by busulfan treatment stimulated a significant increase of TXLNA in SCs at day (d) 14 and d 24 after busulfan treatment, respectively. Consistently, TXLNA expression was steadily upregulated when SCs were co-cultured with apoptotic germ cells (GCs). Moreover, using siRNA treatment, we found that ablation of endogenous TXLNA significantly impaired the phagocytotic capacity of SCs and thereby resulted in defective spermiogenesis and reduced fertility during the late recovery after testicular heat stress. Mechanistically, upregulation of TXLNA expression by apoptotic GCs was associated with the stabilization of ATP-binding cassette transporter 1 (ABCA1), a transporter-mediated lipid efflux from SCs and influencing male fertility. TXLNA acted as an upstream suppressor of ABCA1 ubiquitination and thus promoted ABCA1 stability and accumulation following GC apoptosis. We further provide in vitro evidence that epidermal growth factor receptor (EGFR)-mediated phosphorylation regulated ABCA1 ubiquitination and was enhanced by TXLNA deficiency during testicular phagocytosis. Taken together, the TXLNA/ABCA1 cascade may serve as an important feedback mechanism to modulate the magnitude of subsequent phagocytotic process of SCs in response to testicular injury.

Metastasis-associated protein 2 (MTA2) promotes the metastasis of non-small-cell lung cancer through the inhibition of the cell adhesion molecule Ep-CAM and E-cadherin

OBJECTIVE

Metastasis-associated protein 2 is considered as an intrinsic subunit of the nucleosome remodelling and histone deacetylase complex, which contributes to the epigenetic silencing genes. More and more evidence suggests that metastasis-associated protein 2 is required to maintain the malignant phenotype, but the role of metastasis-associated protein 2 function in mediating tumour metastasis in non-small-cell lung cancer has not been explored.

METHODS

Bioinformatics was used to detect the GEO 3141 database, the online tool of Kmplot was used to confirm the high expression of metastasis-associated protein 2 in influencing 5-year overall survival. Wound-healing assay, Transwell invasion assay and Living imaging assay together showed that MTA2 shRNA inhibited cell migration and invasion in vitro and in vivo. Chromatin immunoprecipitation, quantitative chromatin immunoprecipitation and luciferase reporter assays showed metastasis-associated protein 2 binding on the promoter of the epithelial transmembrane glycoprotein (Ep-CAM) and cell adhesion molecule E-cadherin.

RESULTS

The patient samples collected in our hospital show that metastasis-associated protein 2 was expressed in aggressive lung cancer cells, and its higher expression is correlated with poor prognosis. Metastasis-associated protein 2 promoted cell migration and invasion in vitro and in vivo through binding on the promoter of Ep-CAM and E-cadherin. Luciferase reporter assays showed repressed or enhanced E-cadherin or Ep-CAM promoter-driven luciferase reporter under metastasis-associated protein 2 overexpression or depletion. The changes in the level of protein and RNA implied that suppression of downstream E-cadherin or Ep-CAM was an important mechanism by which metastasis-associated protein 2 triggered epithelial-mesenchymal transition and metastasis.

CONCLUSIONS

Together, our experiments reveal the mechanism for metastasis-associated protein 2 in facilitating invasive potential of non-small-cell lung cancer cells, suggesting that metastasis-associated protein 2 might be a potential therapeutic target for treating the metastasis of non-small-cell lung cancer.