The Axonal Motor Neuropathy-Related HINT1 Protein Is a Zinc- and Calmodulin-Regulated Cysteine SUMO Protease

Abstract

Aims: Histidine triad nucleotide-binding protein 1 (HINT1) exhibits proapoptotic and tumor-suppressive activity. HINT1 binds to transcription factors such as teneurin1 and to the regulator of G protein signaling 17 (RGS) (Z2) protein, which incorporates the small ubiquitin-like modifier (SUMO), and is implicated in several types of cancer. HINT1 interacts with proteins such as PKCγ and Raf-1 through zinc ions provided by the cysteine-rich domain of RGSZ2 and the coupled neural nitric oxide synthase (nNOS). Recently, a series of HINT1 mutants have been reported to cause human autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM). However, the specific alteration in the function of HINT1 induced by these mutants remains to be elucidated. Because sumoylation modifies protein association and transcriptional regulation, we investigated whether HINT1 exhibits zinc- and redox-regulated sumoylase activity, which may be altered in those mutants. Results: HINT1 exhibits cysteine protease activity to remove SUMO from a variety of signaling proteins. HINT1 sumoylase activity is blocked by zinc, and it is released by nitric oxide or calcium-activated calmodulin (CaM). HINT1 contains a SUMO-interacting motif (110–116 HIHLHVL) and the catalytic triad Cys84-Asp87-His114 in the C-terminal region. Thus, zinc probably provided by the RGSZ2–nNOS complex may bind to Cys84 to block HINT1 isopeptidase activity. Innovation: To date, HINT1 is the only sumoylase that is regulated by two alternate pathways, redox- and calcium-activated CaM. Conclusion: The 15 human HINT1 mutants reported to cause ARAN-NM exhibited altered sumoylase activity, which may contribute to the onset of this human motor disease.

Human HINT1 Mutant Proteins that Cause Axonal Motor Neuropathy Exhibit Anomalous Interactions with Partner Proteins

“…HINT1 SUMOylase activity is triggered by calcium-activated CaM and/or NO [2], and in in vitro, HINT1 binds calcium-activated CaM and SUMO1 [2]. All but the shortest HINT1 mutant Q62* were included in the study.…”

“…Previous results show that HINT1 acts as a transcriptional repressor; it is recruited by the DNA damage response [19,20], triggers apoptosis [21] and exhibits tumor-suppressive activity [22][23][24]. RGSZ2 and ICD teneurin 1 incorporate SUMO [2,25], which modi es protein association and transcriptional regulation [26]. HINT1 removes SUMO from these proteins, and this SUMOylase activity appears to be altered in all the ARAN-NM-related HINT1 mutants described so far [2].…”

“…RGSZ2 and ICD teneurin 1 incorporate SUMO [2,25], which modi es protein association and transcriptional regulation [26]. HINT1 removes SUMO from these proteins, and this SUMOylase activity appears to be altered in all the ARAN-NM-related HINT1 mutants described so far [2].…”

“…Histidine triad nucleotide-binding protein 1 (HINT1) is highly phylogenically conserved [1] and belongs to the histidine triad (HIT) family. This 14 kDa protein exhibits zinc-and calmodulin (CaM)-regulated protease activity to remove small-ubiquitin-like modi er (SUMO) from target proteins [2]. In recent years, a rare form of hereditary peripheral neuropathy named autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM) has convincingly being related to mutations in the HINT1 gene.…”

The ALS-Related σ1R E102Q Mutant Eludes Ligand Control and Exhibits Anomalous Response to Calcium

“…The WT σ1R barely forms stable associations with HINT1 [ 31 , 32 ], and thus, the mutant may alter the physiologically stable associations of HINT1 with other signaling proteins. HINT1 is a zinc- and CaM-regulated SUMO protease [ 40 ], and a series of HINT1 mutants have been reported to cause human autosomal recessive axonal neuropathy with neuromyotonia [ 41 ]. The association of the σ1R mutant with the HINT1 protein is relevant to the normal functioning of motor pathways.…”