Pinoresinol promotes MC3T3‑E1 cell proliferation and differentiation via the cyclic AMP/protein kinase�A signaling pathway

Retinoic acid receptor-α (RARA) is crucial for germ cell development in the testis, as shown by the degenerated testis in Rara gene knockout mice, which are sterile. Similarly, FSH is known to regulate Sertoli cell proliferation and differentiation, indirectly controlling the quantity of the spermatogenic output. Interestingly, FSH inhibited, via activation of FSH receptor, cAMP, and protein kinase A (PKA), the nuclear localization and transcriptional activity of RARA. Given that retinoic acid, the ligand for RARA, is known to regulate cell proliferation and differentiation, we investigated whether FSH regulates RARA by a direct posttranslational phosphorylation mechanism. Mutagenesis of serine 219 (S219) and S369 at the PKA sites on RARA to either double alanines or double glutamic acids showed that both PKA sites are important for RARA activity. The negative charges at the PKA sites, whether they are from glutamic acids or phosphorylation of serines, decreased the nuclear localization of RARA, heterodimerization with retinoid X receptor-α, and the transcriptional activity of the receptor. On the other hand, the double-alanine mutant that cannot be phosphorylated at the 219 and 369 amino acid positions did not respond to cAMP and PKA activation. Wild-type and double-mutant RARA interacted with PKA, but only in the presence of cAMP or FSH. These results together suggest that FSH may regulate cell proliferation and differentiation of Sertoli cells, at least partially, by directly affecting the PKA sites of RARA and controlling the transcriptional function of the receptor.

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Protein kinase A activates the Hippo pathway to modulate cell proliferation and differentiation

Genes & Development ◽

10.1101/gad.219402.113 ◽

2013 ◽

Vol 27 (11) ◽

pp. 1223-1232 ◽

Cited By ~ 172

Author(s):

F.-X. Yu ◽

Y. Zhang ◽

H. W. Park ◽

J. L. Jewell ◽

Q. Chen ◽

...

Keyword(s):

Cell Proliferation ◽

Protein Kinase ◽

Protein Kinase A ◽

Hippo Pathway ◽

Cell Proliferation And Differentiation ◽

Proliferation And Differentiation ◽

The Hippo Pathway ◽

Kinase A

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Cross Talk between the Cell Wall Integrity and Cyclic AMP/Protein Kinase A Pathways in Cryptococcus neoformans

mBio ◽

10.1128/mbio.01573-14 ◽

2014 ◽

Vol 5 (4) ◽

Cited By ~ 18

Author(s):

Maureen J. Donlin ◽

Rajendra Upadhya ◽

Kimberly J. Gerik ◽

Woei Lam ◽

Laura G. VanArendonk ◽

...

Keyword(s):

Cell Wall ◽

Protein Kinase ◽

Cyclic Amp ◽

Protein Kinase A ◽

Cryptococcus Neoformans ◽

Signaling Pathway ◽

Cell Wall Integrity ◽

Wild Type ◽

Content Type ◽

Kinase A

ABSTRACTCryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely,PKC1,BCK1,MKK2, andMPK1results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions ofBCK1,MKK2, andMPK1compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis.IMPORTANCECryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.

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