Cdr2, or cerebellar degeneration-related protein 2, is an onconeural antigen. In fission yeast cells, the kinase Cdr2 forms membrane-bound nodes during interphase, which are crucial for controlling the localization of mitotic signaling proteins and the cytokinetic ring, and also play a role in timely cell cycle progression and cell size control [2,3,4,5]. In mammalian cells, it may be involved in regulating ER sheet organization as an adaptor for cytoplasmic dynein-1 [6].

In paraneoplastic cerebellar degeneration (PCD), anti-Yo autoantibodies often target Cdr2 and its paralogue Cdr2L. In a study on PCA-1/anti-Yo paraneoplastic autoimmunity, CDR2 testing alone may produce false-positive results, and optimal performance was achieved by requiring both CDR2 and CDR2L positivity in serum and CDR2L positivity in CSF [1]. Another study found that CDR2 localizes to the nucleus and co-localizes with nuclear speckle proteins, while Yo antibodies specifically bind to CDR2L in Purkinje neurons of PCD patients, potentially interfering with ribosomal machinery function [7].

In conclusion, Cdr2 has diverse functions in cell cycle and size control in fission yeast and may be implicated in the pathogenesis of paraneoplastic cerebellar degeneration. Studies on Cdr2, especially in the context of its role in PCD, help in understanding the disease mechanisms and may contribute to the development of better diagnostic and therapeutic strategies for this autoimmune-related neurological disorder.