HUS1 (HUS1 checkpoint homolog (S. pombe))

2010-09-01   Amrita Madabushi  , Randall C Gunther  , A-Lien Lu  

Department of Biochemistry, Molecular Biology, School of Medicine, University of Maryland, 108 North Greene Street, Baltimore, Maryland 21201, USA

Identity

HGNC
LOCATION
7p12.3
LOCUSID
ALIAS
hHUS1

DNA/RNA

Atlas Image
Figure 1. HUS1 gene adapted from NCBI database Homo sapiens chromosome 7, GrCh37 primary reference assembly with kilobases from the telomere of p-arm on bottom. The exons 1-8 are represented by boxes with transcribed and untranscribed sequences in pink and orange, respectively. The exon numbers are labeled on top. The grey arrowhead symbolizes the direction of transcription and the arrows show the ATG and the stop codons, respectively.

Description

15464 bp; 8 exons.

Transcription

The transcribed mRNA has 2143 bp and the coding region is 840 bp, encodes a 280 amino acids, 31691 Da protein.

Pseudogene

None.

Proteins

Atlas Image
Figure 2. hHus1 and hRad1 associate with each other prior to forming the 9-1-1 complex with Rad9. In response to DNA damage and replication block, the 9-1-1 complex is loaded into DNA by Rad17/RFC clamp loader and acts as checkpoint sensor to activate ATM (ataxia telangiectasia [AT] mutated protein) or ATR (ATM- and Rad3-related protein) protein kinase. The 9-1-1 complex interacts with and stimulates many DNA repair enzymes involved in base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). The damage recognition repair enzymes may serve as adaptors to signal DNA damage responses including enhanced DNA repair, cell cycle arrest, and apoptosis.

Description

Amino acids: 280. Molecular weight: 31.7 kDa. Hus1 is a component of the 9-1-1 cell cycle checkpoint complex that plays a critical role in sensing DNA damage and maintaining genomic stability.

Expression

Found in all tissues.

Localisation

Nucleus and cytoplasm. In discrete nuclear foci upon DNA damage.

Function

Hus1 along with and Rad1 forms the 9-1-1 complex (Hang and Lieberman, 2000; St Onge et al., 1999; Volkmer and Karnitz, 1999). Hus1 and Rad1 can also form a stable 1:1 complex (Doré et al., 2009; Sohn and Cho, 2009; Xu et al., 2009). The 9-1-complex is loaded onto the DNA by a specific clamp loader (Rad17-RFC2-RFC3-RFC4-RFC5) in response to many different genotoxic stresses (alkylation, oxidation, ultraviolet light radiation and ionizing radiation), and replication inhibitors (Bermudez et al., 2003; Ellison and Stillman, 2003). The Rad1-Rad9 interface may be opened to encircle DNA (Doré et al., 2009; Sohn and Cho, 2009; Xu et al., 2009).

The structure of the 9-1-1 complex (Doré et al., 2009; Sohn and Cho, 2009; Xu et al., 2009) is similar to the sliding clamp proliferating cell nuclear antigen protein (PCNA) (Gulbis et al., 1996; Krishna et al., 1994). Hus1 interacts with Rad9 and Rad1 through its N terminal domain and C terminal domain, respectively. The structure and surface charge distribution of the interdomain connecting loop (IDCL) of Hus1 differs from those of other two subunits (Doré et al., 2009; Sohn and Cho, 2009; Xu et al., 2009). The IDCL of Hus1 contains an N-terminal alpha helix and positive charge cluster. These differences among Hus1, Rad9, and Rad1 may contribute to different binding affinities to their partner proteins. For example, MutY homolog (MYH) has a strong preference to bind Hus1 (Chang and Lu, 2005; Shi et al., 2006).

Recent structural and functional analyses indicate that the Hus1 binding region of MYH adopts a stabilized conformation projecting away from the catalytic domain to form a docking scaffold for Hus1 and binds to Hus1 through electrostatic interaction (Luncsford et al., 2010).

The 9-1-1 complex is required to activate two checkpoint sensors-ATM (ataxia telangiectasia [AT] mutated protein) and ATR (ATM- and Rad3-related protein), which are phosphoinositol phosphate 3 kinase-related kinases (PIKKs) (Zhou and Elledge, 2000). The DNA-bound 9-1-1 complex facilitates ATM- or ATR-mediated phosphorylation of more than 700 proteins including Chk1, Chk2, p53, and BRCA1 (Zhou and Elledge, 2000). Hus1 facilitated phosphorylation of Chk1 kinase is required for the ATR-dependent checkpoint; and regulates S-phase progression, G2/M arrest, and replication fork stabilization (Sancar et al., 2004; Sancar et al., 2004). However, Hus1 is not required for Chk2 phosphorylation in response to certain genotoxins (Weiss et al., 2003).

Besides acting as a DNA damage sensor, the 9-1-1 complex plays an integral role in several DNA repair pathways including base excision repair (BER), mismatch repair (MMR), and nucleotide excision repair (NER) (see figure 2) (Helt et al., 2005).

In the BER pathway, the 9-1-1 complex facilitates and interacts with several DNA glycosylases including MYH (Chang and Lu, 2005; Shi et al., 2006; Chang and Lu, 2005; Shi et al., 2006), 8-oxoG glycosylase (OGG1) (Park et al., 2009), NEIL1 (Guan et al., 2007a), and thymine DNA glycosylase (TDG) (Guan et al., 2007b). The 9-1-1 complex also interacts with and stimulates other BER enzymes including APE1 (Gembka et al., 2007), POLbeta (Toueille et al., 2004), FEN1 (Friedrich-Heineken et al., 2005; Wang et al., 2004a), RPA (Wu et al., 2005), and DNA ligase 1 (Smirnova et al., 2005; Wang et al., 2006a). Thus, the 9-1-1 complex may provide a platform for the assembly and function of the BER machinery (Balakrishnan et al., 2009; Lu et al., 2006). The 9-1-1 complex enhances mismatch repair via direct interaction with mismatch recognition proteins (MSH2/MSH3, MSH2/MSH6, and MLH1/PMS2) (Bai et al., 2010; He et al., 2008). Hus1 interacts with MSH2/MSH3 and MSH2/MSH6, but not with MLH1/PMS2 (Bai et al., 2010; He et al., 2008).

In the NER pathway, interactions between Saccharomyces cerevisiae Rad14 (hXPA homolog) and the checkpoint proteins ScDdc1 (hRad9 homolog) and ScMec3 (hHus1 homolog) have been demonstrated (Giannattasio et al., 2004). Inactivation of NER by knock down of XPA and XPC resulted in a decrease of G1 phase cells that displayed Rad9 foci in response to UV light (Warmerdam et al., 2009). UV light-induced Rad9 foci also colocalized with TopBP1 and gamma-H2AX (Warmerdam et al., 2009).

Hus1 interacts with histone deacetylase HDAC1 (Cai et al., 2000). A novel pathway has been proposed that HDAC1 is involved in G(2)/M checkpoint control through the interaction with the 9-1-1 complex.

Jab1 physically associates with the 9-1-1 complex, causes the translocation of the 9-1-1 complex from the nucleus to the cytoplasm, and mediates the rapid degradation of the 9-1-1 complex (Huang et al., 2007).

Homology

hHus1 homologues from many eukaryotes are highly conserved. The following diagram shows the sequence alignment of human Hus1 with Hus1 of fission yeast Schizosaccharomyces pombe. The N-terminal domain of Hus1 is structurally similar to the C-terminal domain. The structure of Hus1 (Doré et al., 2009; Sohn and Cho, 2009; Xu et al., 2009) is similar to those of Rad9, Rad1, and PCNA (Gulbis et al., 1996; Krishna et al., 1994).
Atlas Image
Figure 3. Sequence alignment of the human Hus1 (hHus1) and S. pombe (SpHus1) with secondary structure motifs shown corresponding to the hHus1 based on hHus1 crystal structure (Xu et al., 2009). The arrows and coils represent the beta-sheets and alpha-helix, respectively. Hus1 contains 18 beta sheets and 5 alpha helices. Its N terminal and C terminal domains are connected by an interdomain connecting loop (IDCL, residues 134-155). The yellow shaded regions are the identical residues between hHus1 and SpHus1.

Mutations

Note

Complete inactivation of the mouse Hus1 results in chromosomal instability, genotoxin hypersensitivity, and embryonic lethality.

Implicated in

Entity name
Breast cancer
Note
Hus1 inactivation in the mammary epithelium resulted in genome damage that induced apoptosis and led to depletion of Hus1-null cells from the mammary gland. Dual inactivation of Hus1 and p53 in the mouse mammary gland results in accumulation of damaged cells and impaired tissue regeneration (Yazinski et al., 2009).
Oncogenesis
Single nucleotide polymorphism (SNP) analysis supports the potential role of Hus1 in sporadic breast cancer (Vega et al., 2009). SNPs in hHUS1 at chromosome 7 base pair positions 47778020 (C) and 47789957 (G) are statistically associated with breast cancer development (Vega et al., 2009).
Entity name
Ovarian tumors
Oncogenesis
Hus1 expression levels correlate significantly with the clinicopathologic factors of bad prognosis of ovarian tumors (de la Torre et al., 2008).
Entity name
Cancer therapy
Note
The status of Hus1 can influence response to cancer therapy. Down-regulation of hHus1 by antisense RNA enhances the sensitivity of human lung carcinoma cells to cisplatin (a DNA cross-linker), presumably by enhancing apoptosis (Kinzel et al., 2002).
Entity name
Genomic stability
Note
Inactivation of mouse or human Hus1 results in impaired DNA damage signaling and severe spontaneous chromosomal instability (Weiss et al., 2002; Weiss et al., 2000; Kinzel et al., 2002).
Entity name
Drug sensitivity
Note
Cells lacking Hus1 are hypersensitive to certain genotoxins including camptothecin (CPT), hydroxyurea (HU), ultraviolet (UV), and ionizing radiation (IR) (Weiss et al., 2000; Wang et al., 2004b; Wang et al., 2006b). Loss of Hus1 sensitizes the cells to etoposide-induced apoptosis by inducing Bim and Puma expressions and releasing Rad9 into the cytosol (Levitt et al., 2005; Levitt et al., 2007; Meyerkord et al., 2008). The role of Hus1 affecting the sensitivity of cells to IR-induced killing is independent of nonhomologous end-joining (NHEJ) but might be linked to homologous recombination repair (HRR) (Wang et al., 2006b).
Entity name
Development
Note
Targeted deletion of mouse Hus1 results in embryonic lethality (Weiss et al., 2000).
Entity name
Telomere maintenance
Note
Severe telomere shortening has been observed in both Hus1-deficient mouse embryonic fibroblasts and thymocytes from conditional Hus1-knockout mice (Francia et al., 2006).
Entity name
HIV infection (AIDS)
Note
Hus1 is required for Human Immunodeficiency Virus type 1 Vpr-mediated G2 cell cycle arrest (Zimmerman et al., 2004).

Article Bibliography

Pubmed IDLast YearTitleAuthors

Other Information

Locus ID:

NCBI: 3364
MIM: 603760
HGNC: 5309
Ensembl: ENSG00000136273

Variants:

dbSNP: 3364
ClinVar: 3364
TCGA: ENSG00000136273
COSMIC: HUS1

RNA/Proteins

Gene IDTranscript IDUniprot
ENSG00000136273ENST00000258774O60921
ENSG00000136273ENST00000258774A4D2F2
ENSG00000136273ENST00000432325O60921
ENSG00000136273ENST00000432627C9JCK8
ENSG00000136273ENST00000433977F8WAW9
ENSG00000136273ENST00000442024H7C272
ENSG00000136273ENST00000446009C9JA95
ENSG00000136273ENST00000458191O60921

Expression (GTEx)

0
5
10
15

Pathways

PathwaySourceExternal ID
Gene ExpressionREACTOMER-HSA-74160
Generic Transcription PathwayREACTOMER-HSA-212436
Transcriptional Regulation by TP53REACTOMER-HSA-3700989
Cell CycleREACTOMER-HSA-1640170
Cell Cycle CheckpointsREACTOMER-HSA-69620
G2/M CheckpointsREACTOMER-HSA-69481
G2/M DNA damage checkpointREACTOMER-HSA-69473
Activation of ATR in response to replication stressREACTOMER-HSA-176187
DNA RepairREACTOMER-HSA-73894
DNA Double-Strand Break RepairREACTOMER-HSA-5693532
Homology Directed RepairREACTOMER-HSA-5693538
HDR through Homologous Recombination (HR) or Single Strand Annealing (SSA)REACTOMER-HSA-5693567
Processing of DNA double-strand break endsREACTOMER-HSA-5693607
HDR through Homologous Recombination (HRR)REACTOMER-HSA-5685942
Homologous DNA Pairing and Strand ExchangeREACTOMER-HSA-5693579
Presynaptic phase of homologous DNA pairing and strand exchangeREACTOMER-HSA-5693616
HDR through Single Strand Annealing (SSA)REACTOMER-HSA-5685938
Regulation of TP53 ActivityREACTOMER-HSA-5633007
Regulation of TP53 Activity through PhosphorylationREACTOMER-HSA-6804756

Protein levels (Protein atlas)

Not detected
Low
Medium
High

References

Pubmed IDYearTitleCitations
337113832021MiR-340-3p-HUS1 axis suppresses proliferation and migration in lung adenocarcinoma cells.3
337113832021MiR-340-3p-HUS1 axis suppresses proliferation and migration in lung adenocarcinoma cells.3
331370862020In vivo miRNA knockout screening identifies miR-190b as a novel tumor suppressor.9
331370862020In vivo miRNA knockout screening identifies miR-190b as a novel tumor suppressor.9
301823782019HUS1 checkpoint clamp component (HUS1) is a potential tumor suppressor in primary hepatocellular carcinoma.6
301823782019HUS1 checkpoint clamp component (HUS1) is a potential tumor suppressor in primary hepatocellular carcinoma.6
259111002015Genome Protection by the 9-1-1 Complex Subunit HUS1 Requires Clamp Formation, DNA Contacts, and ATR Signaling-independent Effector Functions.0
260881382015Intramolecular Binding of the Rad9 C Terminus in the Checkpoint Clamp Rad9-Hus1-Rad1 Is Closely Linked with Its DNA Binding.7
263776312015Distinct functional consequences of MUTYH variants associated with colorectal cancer: Damaged DNA affinity, glycosylase activity and interaction with PCNA and Hus1.16
266001722015The Roles of p21(Waf1/CIP1) and Hus1 in Generation and Transmission of Damage Signals Stimulated by Low-Dose Alpha-Particle Irradiation.1
259111002015Genome Protection by the 9-1-1 Complex Subunit HUS1 Requires Clamp Formation, DNA Contacts, and ATR Signaling-independent Effector Functions.0
260881382015Intramolecular Binding of the Rad9 C Terminus in the Checkpoint Clamp Rad9-Hus1-Rad1 Is Closely Linked with Its DNA Binding.7
263776312015Distinct functional consequences of MUTYH variants associated with colorectal cancer: Damaged DNA affinity, glycosylase activity and interaction with PCNA and Hus1.16
266001722015The Roles of p21(Waf1/CIP1) and Hus1 in Generation and Transmission of Damage Signals Stimulated by Low-Dose Alpha-Particle Irradiation.1
240620752013Expression of cell cycle regulatory factors hus1, gadd45a, rb1, cdkn2a and mre11a correlates with expression of clock gene per2 in human colorectal carcinoma tissue.8

Citation

Amrita Madabushi ; Randall C Gunther ; A-Lien Lu

HUS1 (HUS1 checkpoint homolog (S. pombe))

Atlas Genet Cytogenet Oncol Haematol. 2010-09-01

Online version: http://atlasgeneticsoncology.org/gene/40899/hus1