Elsevier

Gene

Volume 264, Issue 1, 7 February 2001, Pages 37-44
Gene

Characterization and tissue expression of a novel human gene npdc1

https://doi.org/10.1016/S0378-1119(01)00324-9Get rights and content

Abstract

We report the molecular characterization of a novel human homologue of mouse npdc1 (neural proliferation, differentiation and control, 1) gene, designated human npdc1 (hnpdc1). hnpdc1 was identified by large-scale sequencing of fetal liver cDNA libraries and the full-length cDNA was obtained by PCR amplification. The hnpdc1 gene, which contains nine exons, was mapped to human chromosome 15. It encodes a polypeptide of 325 amino acids, which shows high homology (77% identity) to the mouse NPDC1. Sequence analysis has shown that hNPDC1 protein contains a putative signal peptide of 34 amino acids, a transmembrane segment, and a typical bipartite nuclear localization signal. Northern blot and dot blot hybridization indicates that, just like mnpdc1, hnpdc1 mRNA is strongly expressed in adult brain (especially in hippocampus, frontal lobe and temporal lobe) and about 1.82-fold higher in adult brain than that in fetal brain. Unlike mnpdc1, however, hnpdc1 contains two transcripts instead of only one (1.5 kb), and has high expression levels in prostate, pituitary gland, and mammary glands. These results support that hNPDC1 plays a role in the control of neural cell proliferation and differentiation, and suggest that it may be involved in the development of several secretion glands.

Introduction

Transcription factors in the basic-helix-loop-helix (bHLH) family are key regulators in development, particularly in cell-type determination, terminal differentiation, and sex determination (Yang et al., 2000). Within the last decade, several mammalian neural HLH proteins have been found to play critical roles in neural terminal differentiation, such as MASH-1 and -2 (Johnson et al., 1990, Horton et al., 1999), MATH-1 and -2 (Akazawa et al., 1995), NeuroD (Lee et al., 1995, Liu et al., 2000), neurogenin (Ma et al., 1996), HES-1 and -2 (Sasai et al., 1992, Ishibashi et al., 1993). These results promoted a lot of researchers to search for novel mammalian HLH factors which may be involved in the specific control of neural cell proliferation and differentiation.

Many new genes have been identified from human fetal liver during recent years with the progress of large-scale cDNA sequencing project in our lab (Yang et al., 1997, Wang et al., 1999, Zhang et al., 2000). Up to date, more than 18 000 expressed sequence tags (ESTs) have been analyzed to search the non-redundant GenBank database with the Blast program. Among these ESTs, an insert clone FLD2599 encodes a putative partial polypeptide of 305 amino acids, and a segment (LEEEIDSLAQELALKE) in amino-terminal of the polypeptide shows moderate homology with HLH domains in several known regulatory factors (e.g. amino acids 190–207 of Fos B and amino acids 276–285 of c-Jun). So this clone was selected and extended towards the 5′ end by PCR amplification of cDNA ends. This has led to obtain the entire coding sequence of a novel human gene, which shows high homology to the mouse npdc1 (mnpdc1) and so we term it hnpdc1 (human neural proliferation, differentiation and control, 1). The neural-specific mnpdc1 cDNA was isolated from postnatal mouse brain by using oligonucleotides derived from HLH recognition sequences as probes (Gallana et al., 1995). The protein mNPDC1 does not belong to any known HLH subfamily, although it contains an HLH-like domain. It down-regulated cell proliferation and its expression was maintained in growth-arrested and differentiated cells (Dupont et al., 1998). Here we report the sequence features of the cDNA and the predictive protein, gene identification, chromosomal assignment and tissue expression of hnpdc1.

Section snippets

Identification and cloning of hnpdc1

In our lab, a cDNA library of human fetal liver (second trimester) was selected for large-scale DNA sequencing to search novel genes with important functions. An on-line Blast search was performed against the public EST and non-redundant GenBank database with the EST sequence (Altschul et al., 1997). The clone FLD2599 susceptible of encoding a protein with HLH-like domain was picked up for further analysis.

5′-Rapid amplification of cDNA ends (RACE)

A new generation of SMART™ RACE cDNA Amplification Kit (CLONTECH) was used. MMLV reverse

Identification and cloning of hnpdc1

After sequencing the cDNA library of human fetal liver and searching the non-redundant GenBank database, a cDNA clone (No. FLD2599) susceptible of encoding protein with HLH-like domain and homologous to mnpdc1 cDNA was selected for further study. The insertion segment of this clone was 1283 bp (including 61 adenine bases at 3′ terminal) in size and included an open reading frame (ORF) of 918 nucleotides that lacked an initiation codon. Since the segment contains poly(A) addition signal and

Acknowledgements

This subject was partially supported by Chinese National Natural Sciences Foundation (30070177), Chinese National Natural Sciences Foundation Key Project (39730310), Chinese National Key Project of Basic Research and Chinese High-tech Program.

References (23)

  • E. Gallana et al.

    Identification of a neural-specific cDNA, NPDC-1, able to down-regulate cell proliferation and to suppress transformaion

    Proc. Natl. Acad. Sci. USA

    (1995)
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