ACP2

ACP2 Full Name

acid phosphatase 2, lysosomal

ACP2 Introduction

Acid phosphatase 2 (ACP2), commonly known as lysosomal acid phosphatase, is a crucial metabolic enzyme belonging to the histidine acid phosphatase family. Localized primarily within the lysosomal membrane, ACP2 operates optimally in the highly acidic environment of the lysosome (pH 4.0-5.0). Structurally functioning as a dimer, its fundamental biological role involves the hydrolysis of orthophosphoric monoesters to generate free alcohol and phosphate. Through this catalytic activity, ACP2 is indispensable for the proper breakdown of complex macromolecules, the regulation of mannose-6-phosphate levels, and the maintenance of overall lysosomal homeostasis. By ensuring the efficient functioning of autophagic clearance pathways, ACP2 plays a vital protective role in cellular health, particularly in post-mitotic cells such as neurons that are highly sensitive to the accumulation of metabolic waste.

Figure 1. LAP/ACP2 shuttles several times between the plasma membrane end endosomes. (Source: Rudnik S, et al. 2021)

Because of its central role in cellular "waste management," the dysregulation or genetic mutation of ACP2 is closely linked to several severe human pathologies, predominantly lysosomal storage disorders and neurodegenerative diseases. In mammalian models, loss-of-function mutations in the ACP2 gene result in profound lysosomal storage defects in the central nervous system and kidneys. This biochemical failure manifests clinically as severe cerebellar ataxia, progressive neurodegeneration, early-onset seizures, and hair-follicle abnormalities. Emerging evidence also links aberrant ACP2 activity to human neurodegenerative conditions, where altered lysosomal enzyme levels indicate critical cellular stress and an inability to clear toxic aggregates.

Beyond congenital metabolic and neurological disorders, ACP2 has recently gained significant attention in the field of oncology. As cancer cells undergo metabolic reprogramming, they often exploit lysosomal pathways to fuel rapid proliferation and survive microenvironmental stress. Consequently, ACP2 expression is frequently altered in various solid tumors. Notably, in colorectal cancer, elevated ACP2 expression serves as both an unfavorable prognostic factor for overall disease progression and, paradoxically, a predictive biomarker for increased sensitivity to certain chemotherapies. As our understanding of lysosomal functions deepens, targeting ACP2 and its associated autophagic pathways holds considerable promise for developing novel therapeutic interventions in both neurodegenerative diseases and cancer.

Alternate Names for ACP2

ACP2; acid phosphatase 2, lysosomal; lysosomal acid phosphatase; LAP;

• 1. Rudnik S, et al. The lysosomal membrane-export of metabolites and beyond. FEBS J. 2021 Jul;288(14):4168-4182.
  2. Lee YC, et al. Lysosomal acid phosphatase 2 is an unfavorable prognostic factor but is associated with better survival in stage II colorectal cancer patients receiving chemotherapy. Oncotarget. 2017 Feb 14;8(7):12120-12132.