PNPLA2

PNPLA2 Full Name

patatin-like phospholipase domain containing 2

PNPLA2 Introduction

Patatin-like phospholipase domain-containing protein 2 (PNPLA2), almost universally known in molecular biology as adipose triglyceride lipase (ATGL), is the paramount rate-limiting enzyme initiating intracellular lipolysis. Localized dynamically to the surface of intracellular lipid droplets, PNPLA2 catalyzes the first and most critical step in the catabolism of stored fat: the hydrolysis of triacylglycerol (TAG) into diacylglycerol (DAG) and a free fatty acid. This fundamental enzymatic action requires complex physical association with its indispensable co-activator, comparative gene identification-58 (CGI-58). By mobilizing lipid stores, PNPLA2 dictates systemic lipid homeostasis and ensures a steady supply of free fatty acids for mitochondrial beta-oxidation during periods of energy demand, fasting, or acute exercise. Its physiological importance extends far beyond white adipose tissue, serving as a critical metabolic regulator in the liver, skeletal muscle, and the myocardium, where it prevents ectopic lipid toxicity.

Figure 1. Two pathways of lipolysis. (Source: Zhang X, et al. 2019)

Clinically, the dysregulation or genetic mutation of PNPLA2 triggers profound, tissue-specific metabolic pathologies. Recessive loss-of-function mutations in the PNPLA2 gene directly cause Neutral Lipid Storage Disease with Myopathy (NLSDM). This is a rare, severe disorder biochemically characterized by the massive, irreversible ectopic accumulation of TAGs in muscle fibers and leukocytes, ultimately leading to progressive skeletal myopathy and devastating, often fatal, cardiomyopathy. Beyond rare congenital disorders, altered PNPLA2 activity is deeply intertwined with highly prevalent modern diseases. In the liver, impaired PNPLA2 function exacerbates hepatic steatosis and accelerates metabolic dysfunction-associated steatotic liver disease (MASLD). Conversely, the pathological hyperactivation of PNPLA2 is a major systemic driver of cancer cachexia—a state where rampant, uncontrolled lipolysis leads to the devastating depletion of host adipose tissue and severe metabolic wasting. Consequently, PNPLA2 represents a highly sensitive molecular node: its targeted pharmacological inhibition is currently being explored to combat cancer cachexia, while preserving its baseline function is vital for averting heart failure and metabolic lipotoxicity.

Alternate Names for PNPLA2

PNPLA2; patatin-like phospholipase domain containing 2; ATGL; TTS2; PEDF-R; FP17548; TTS-2.2; iPLA2zeta; 1110001C14Rik; patatin-like phospholipase domain-containing protein 2

• 1. Zhang X, et al. An Epistatic Interaction between Pnpla2 and Lipe Reveals New Pathways of Adipose Tissue Lipolysis. Cells. 2019 Apr 29;8(5):395.
  2. Grabner GF, et al. Lipolysis: cellular mechanisms for lipid mobilization from fat stores. Nat Metab. 2021 Nov;3(11):1445-1465.