Ubiquitin C-terminal Hydrolase L1 Expression Research Articles

Ubiquitin C-terminal hydrolase-L1 is a key regulator of tumor cell invasion and metastasis

Ubiquitin C-terminal hydrolase-L1 (UCH-L1) catalyses the hydrolysis of ubiquitin ester and amide mainly in neuronal cells. Recently it was proposed as a marker with a potential role in carcinogenesis. However, the molecular mechanism underlying the biological function of UCH-L1 in tumor cells is poorly understood. We found that UCH-L1 is highly expressed in non-small lung cancer cell line H157, having high invasive potential, and that the expression of UCH-L1 in tumor cells enhances their invasive potential in vitro and in vivo. UCH-L1 changes cell morphology by regulating cell adhesion through Akt-mediated pathway. Suppressing UCH-L1 expression by RNAi significantly suppressed the invasion in vitro and in vivo, and the activation of Akt and downstream mitogen activated protein kinases c-Jun N-terminal kinases and p38, but not ERK. In Akt-negative mutants, overexpression of UCH-L1 does not affect the invasion and migration capability of H157 cells. These results suggest that UCH-L1 is a key molecule to regulate tumor-cell invasion by upstream activation of Akt.

Aberrant Interaction between Parkinson Disease-associated Mutant UCH-L1 and the Lysosomal Receptor for Chaperone-mediated Autophagy

Parkinson disease (PD) is the most common neurodegenerative movement disorder. An increase in the amount of alpha-synuclein protein could constitute a cause of PD. Alpha-synuclein is degraded at least partly by chaperone-mediated autophagy (CMA). The I93M mutation in ubiquitin C-terminal hydrolase L1 (UCH-L1) is associated with familial PD. However, the relationship between alpha-synuclein and UCH-L1 in the pathogenesis of PD has remained largely unclear. In this study, we found that UCH-L1 physically interacts with LAMP-2A, the lysosomal receptor for CMA, and Hsc70 and Hsp90, which can function as components of the CMA pathway. These interactions were abnormally enhanced by the I93M mutation and were independent of the monoubiquitin binding of UCH-L1. In a cell-free system, UCH-L1 directly interacted with the cytosolic region of LAMP-2A. Expression of I93M UCH-L1 in cells induced the CMA inhibition-associated increase in the amount of alpha-synuclein. Our findings may provide novel insights into the molecular links between alpha-synuclein and UCH-L1 and suggest that aberrant interaction of mutant UCH-L1 with CMA machinery, at least partly, underlies the pathogenesis of PD associated with I93M UCH-L1.

The Region-Specific Functions of Two Ubiquitin C-Terminal Hydrolase Isozymes along the Epididymis

We previously showed that gad mice, which are deficient for ubiquitin C-terminal hydrolase L1 (UCH-L1), have a significantly increased number of defective spermatozoa, suggesting that UCH-L1 functions in sperm quality control during epididymal maturation. The epididymis is the site of spermatozoa maturation, transport and storage. Region-specific functions along the epididymis are essential for establishing the environment required for sperm maturation. We analyzed the region-specific expression of UCH-L1 and UCH-L3 along the epididymis, and also assessed the levels of ubiquitin, which has specificity for UCH-L1. In wild-type mice, western blot analysis demonstrated a high level of UCH-L1 expression in the caput epididymis, consistent with ubiquitin expression, whereas UCH-L3 expression was high in the cauda epididymis. We also investigated the function of UCH-L1 and UCH-L3 in epididymal apoptosis induced by efferent duct ligation. The caput epididymides of gad mice were resistant to apoptotic stress induced by efferent duct ligation, whereas Uchl3 knockout mice showed a marked increase in apoptotic cells following ligation. In conclusion, the response of gad and Uchl3 knockout mice to androgen withdrawal suggests a reciprocal function of the two UCH enzymes in the caput epididymis.

Ubiquitin C-terminal hydrolase-L1 (PGP9.5) expression in human neural cell lines following induction of neuronal differentiation and exposure to cytokines, neurotrophic factors or heat stress.

Dysfunction of the ubiquitin-dependent proteolytic pathway contributes to progressive accumulation of ubiquitinated protein inclusions in neurodegenerative disorders, such as Parkinson's disease (PD). Ubiquitin C-terminal hydrolase-L1 (UCH-L1), alternatively designated protein gene product 9.5 (PGP9.5), is a neural deubiquitinating enzyme which is identified as a principal constituent of Lewy bodies. To clarify the regulatory mechanism of UCH-L1 expression in human neural cells, we studied the constitutive, cytokine/neurotrophic factor-regulated, and heat stress-induced expression of UCH-L1 in cultured human neural cell lines by Western blot analysis. The constitutive expression of UCH-L1 was identified in SK-N-SH neuroblastoma cells, IMR-32 neuroblastoma cells, U-373MG astrocytoma cells, and NTera2 teratocarcinoma-derived differentiated neurones (NTera2-N). The levels of UCH-L1 expression were unaltered in these cell lines following treatment with TNF-alpha, IL-1beta, BDNF, GDNF, dibutyryl cyclic AMP, or phorbol 12-myristate 13-acetate, and remained unchanged by exposure to heat stress. In contrast, its levels were elevated substantially in NTera2 teratocarcinoma cells following retinoic acid-induced neuronal differentiation, accompanied with an increased expression of alpha-synuclein and synaptophysin. These results indicate that UCH-L1 is expressed constitutively in human neual cell lines, where it is upregulated following induction of neuronal differentiation, but unaffected by exposure to heat stress, cytokines, or growth/differentiation factors which are supposed to be invloved in the nigral neuronal death and survival in PD.