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Analysis of expression of PP1γ isoforms in testis by laser capture microdissection suggests a role for PP1γ2 in protein expression in differentiating spermatids
Author(s) -
Chakrabarti Rumela,
Puri Pawan,
Shibata Haruna,
Kline Douglas,
Vijayaraghavan Srinivasan
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a618-c
Subject(s) - biology , spermatid , spermatogenesis , laser capture microdissection , messenger rna , spermiogenesis , gene isoform , microbiology and biotechnology , gene expression , gene , genetics , endocrinology
Serine/threonine protein phosphatase 1 (PP1) consists of four major isoforms, two of which, PP1γ1 and PP1γ2, are derived by alternative splicing of a single gene, Ppp1cc . Targeted disruption of the Ppp1cc causes infertility in male mice due to impaired spermiogenesis. In this study, we used laser capture microdissection (LCM) and Reverse transcriptase‐polymerase chain reaction to examine the pattern of expression of mRNA for PP1γ1 and PP1γ2 in germ cells in testis of adult mice. PP1γ1 mRNA was only detected in spermatogonia and pachytene spermatocytes. PP1γ2 mRNA was present in spermatogonia, pachytene spermatocytes, round spermatids and elongating spermatids indicating that it is the only isoform of PP1γ present in post meiotic germ cells. We also observed an age‐dependent increase in PP1γ2 transcripts in comparison to PP1γ1 in developing testes. Spermatogenesis appears to proceed normally up until the transition from round spermatids to elongating spermatids in Ppp1cc null mice. We analyzed mRNA and proteins of spermatid specific genes‐AKAP4, odf2, sds22 in round spermatids of wild‐type and null testes. Comparable levels of mRNAs for these proteins were present in round spermatids in both null testes and wild type testes. However, immunoblotting showed that these proteins were absent or present in highly reduced levels in null compared to wild type testes. Immunohistochemistry confirmed reduced expression of AKAP4, odf2 and sds22 proteins in round and elongating spermatids in Ppp1cc null testes. Our findings suggest that PP1γ2 may play a role in mRNA translation or stability of post‐meiotically expressed proteins (Supported by NIH HD38520 SV).