Identification and characterization of calcium binding protein, spermatid-associated 1 (CABS1)# in selected human tissues and fluids.

Calcium binding protein, spermatid associated 1 (CABS1) is a protein most widely studied in spermatogenesis. However, mRNA for CABS1 has been found in numerous tissues, albeit with little information about the protein. Previously, we identified CABS1 mRNA and protein in human salivary glands and provided evidence that in humans CABS1 contains a heptapeptide near its carboxyl terminus that has anti-inflammatory activities. Moreover, levels of an immunoreactive form of CABS1 were elevated in psychological stress. To more fully characterize human CABS1 we developed additional polyclonal and monoclonal antibodies to different sections of the protein and used these antibodies to characterize CABS1 in an overexpression cell lysate, human salivary glands, saliva, serum and testes using western blot, immunohistochemistry and bioinformatics approaches exploiting the Gene Expression Omnibus (GEO) database. CABS1 appears to have multiple molecular weight forms, consistent with its recognition as a structurally disordered protein, a protein with structural plasticity. Interestingly, in human testes, its cellular distribution differs from that in rodents and pigs, and includes Leydig cells, primary spermatogonia, Sertoli cells and developing spermatocytes and spermatids, Geodata suggests that CABS1 is much more widely distributed than previously recognized, including in the urogenital, gastrointestinal and respiratory tracts, as well as in the nervous system, immune system and other tissues. Much remains to be learned about this intriguing protein.
Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: A. Dean Befus, together with the University of Alberta holds a patent on CABS1 as a biomarker of stress, and an associated licensing agreement with GB Diagnostics, 10515302 Canada Inc. Aron Gonshor and Robert Buck are co-owners of GB Diagnostics 10515302 Canada Inc. GB Diagnostics helped with the processing of the application and partially funded the approved USA patent 16/084,617, entitled: Calcium Binding Protein, Spermatid Specific 1, as a Biomarker for Diagnosis or Treatment of Stress. The company is also assisting with the application and partially funding of the Canadian National Application No. CA 3,017,604, Calcium Binding Protein, Spermatid Specific 1, as a Biomarker for Diagnosis or Treatment of Stress (pending approval). GB Diagnostics 10515302 Canada Inc. is developing a stress biomarker test for commercial application under its licensing agreement with the University of Alberta. The commercial affiliation with GB Diagnostics Canada Inc. does not alter our adherence to PLOS ONE policies on sharing data and materials for this manuscript.
(Copyright: © 2024 Reyes-Serratos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)