E3 ubiquitin-protein ligase NHLRC1 (NHLRC1)

E3 ubiquitin-protein ligase NHLRC1, also known as Malin, is a RING-type E3 ubiquitin ligase that plays a vital role in regulating glycogen metabolism and maintaining protein quality control within the cell. It forms a functional complex with the dual-specificity phosphatase laforin to ubiquitinate and promote the degradation of proteins involved in glycogen synthesis, such as PTG (protein targeting to glycogen), thereby preventing the accumulation of abnormal, insoluble glycogen. Loss-of-function mutations in the NHLRC1 gene are a primary cause of Lafora disease, a fatal and rapidly progressive neurodegenerative disorder characterized by severe epilepsy, cognitive decline, and the presence of pathognomonic Lafora bodies in the brain and other tissues. Beyond its role in neurodegeneration, recent studies have identified NHLRC1 as a potential oncogene in lung cancer, where its overexpression—often driven by DNA hypomethylation—leads to the activation of the AKT signaling pathway and promotes tumor cell proliferation and invasion. While there are currently no approved small molecule drugs that directly target NHLRC1, it is a major focus of therapeutic research, particularly for gene replacement strategies in Lafora disease and as a potential inhibitory target in oncology. Current clinical management of Lafora disease remains symptomatic, focusing on the use of anti-seizure medications while disease-modifying therapies like antisense oligonucleotides and gene therapies are under development.

Other names

MalinEPM2BNHL repeat-containing protein 1RING-type E3 ubiquitin transferase NHLRC1EPM2

NHLRC1 functions as an E3 ubiquitin ligase that, in complex with the phosphatase laforin, ubiquitinates substrates such as protein targeting to glycogen (PTG) and glycogen synthase to regulate glycogen synthesis and prevent the formation of insoluble polyglucosan aggregates. In cancer, it may act as an AKT activator to promote cell survival and proliferation.