Phosphopeptides from proteins involved in regulation of transcription that are altered in abundance in response to dDAVP in rat IMCD suspensions* (See below for narrative)
*Peptides satisfied dual criteria: |Mean log2(dDAVP/Control)| > 0.342 and FDR < 0.005. The value 0.342 defines the 95% confidence interval for control:control comparisons.
§, Phosphorylated amino acid indicated by *; #, deamidated asparagine or glutamine; †, False Discovery Rate; ‡ Imported from "FUNCTION" field of UniProt record
| Gene Symbol |
UniProt no. |
Residue(s) |
Peptide§ |
Mean log2(dDAVP/Vehicle) |
SD log2(dDAVP/Vehicle) |
FDR† |
Function in regulation of transcription‡ |
Ajuba,Q5U2Z2,S89,GS*FEAQR,0.733,0.048,3.97E-08,"Involved in signal transduction from cell adhesion sites to the nucleus. Acts as a transcriptional corepressor for SNAI1 and SNAI2/SLUG-dependent repression of E-cadherin transcription in EMT.",
Apc,P70478,S2793,SS*ADSTSARPSQIPTPVGSSTK,1.060,0.231,2.04E-11,"Participates in Wnt signaling as a negative regulator. Promotes rapid degradation of CTNNB1. Interacts with Axin.",
Ctnnb1,Q9WU82,T551,RT*SM@GGTQQQFVEGVR,0.831,0.135,1.73E-08,"Component of the canonical Wnt signaling pathway. Without Wnt, forms a complex with AXIN1, AXIN2, APC, CSNK1A1 and GSK3B. In the presence of Wnt, CTNNB1 accumulates in the nucleus, where it acts as a coactivator for transcription factors, leading to activation of Wnt responsive genes.",
Ctnnb1,Q9WU82,S552,RTS*M@GGTQQQFVEGVR,0.771,0.094,5.13E-08,"Same as above.",
Erc1,Q811U3,S17;S21,VEPSSQS*PGRS*PR,-0.566,0.184,3.98E-05,"Regulatory subunit of the IKK complex. Part of a complex with CHUK, IKBKB and IKBKG. Interacts with NFKBIA.",
Lrrfip1,Q66HF9,S88,RGS*GDTSISM@DTEASIR,0.893,0.295,1.11E-08,"Transcriptional repressor which preferentially binds to the GC-rich consensus sequence (5'-AGCCCCCGGCG-3') and may regulate expression of TNF, EGFR and PDGFA. Positively regulates Toll-like receptor (TLR) signaling.",
Lrrfip2,Q4V7E8,S133,GS*GDTSSLIDPDTSLSELR,0.566,0.148,2.64E-05,"Activator of the canonical Wnt signaling pathway, in association with DVL3, upstream of CTNNB1/beta-catenin. Positively regulates Toll-like receptor (TLR) signaling.",
Luzp1,Q9ESV1,S261,GS*LDYLK,0.909,0.117,1.09E-09,"Uncharacterized nuclear leucine-zipper protein.",
Maf1,Q5XIH0,S75,S*QGGEDESPLSDK,0.598,0.336,5.72E-05,"Inhibits the de novo assembly of TFIIIB onto DNA Phosphorylated at Ser-60, Ser-68 and Ser-75. Nuclear accumulation correlates with a concomitant dephosphorylation.",
Nf1,P97526,S2504,SMS*LDMGQPSQANTK,0.598,0.168,1.59E-05, "Stimulates the GTPase activity of Ras. Interacts with HTR6. Nucleus.",
Pip5k1a,D3ZSI8,S55,SVDS*SGETTYK,0.643,0.177,5.77E-06,"Forms a complex with CDH1/E-cadherin, CTNNB1/beta-catenin and CTNND1 at the plasma membrane upon calcium stimulation.",
Psen1,P97887,T371;S372,AAVQELSGS?ILT*S*EDPEER,0.658,0.299,1.03E-05,"Plays a role in Notch and Wnt signaling cascades and regulation of downstream processes by processing key regulatory proteins. Increases the pool of cytoplasmic CTNNB1, and thereby regulates Wnt signaling.",
Tcea1,Q4KLL0,S57,KQS*TDEEVTSLAK,0.533,0.049,6.45E-06,"Necessary for efficient RNA polymerase II transcription elongation past arresting sites. Forms a transcription regulatory complex of CDK9, RNAP II, UBR5 and TCEA1 that can stimulate target gene transcription by recruiting their promoters.",
Thrap3,Q5M7V8,S737;S743,SRES*VDSRDS*SHSR,-0.551,0.266,1.12E-04,"Enhances the transcriptional activation mediated by PPARG. Role in the terminal stage of adipocyte differentiation. Acts as a coactivator of the CLOCK-ARNTL/BMAL1 heterodimer and promotes its transcriptional activator activity.",
Trim28,O08629,S595;T600,LAS*PSGST*SSGLEVVAPEVTSAPVSGPGILDDSATIC^R,0.738,1.075,8.60E-06,"Nuclear corepressor for KRAB-ZFPs. Recruitment of SETDB1 induces heterochromatinization. Role as a coactivator for CEBPB and NR3C1.Inhibits E2F1 activity by stimulating E2F1-HDAC1 complex formation and inhibiting E2F1 acetylation.",
Trim28,O08629,S595;S597,LAS*PS*GSTSSGLEVVAPEVTSAPVSGPGILDDSATIC^R,-0.849,0.704,2.00E-07,"Same as above.",
Yap1,Q2EJA0,S363,DES*TDSGLSMSSYSIPR,0.472,0.2712,6.60E-04,"Transcriptional coregulator that s the critical downstream regulatory target in the Hippo signaling pathway that plays a pivotal role in organ size control. Phosphorylation by LATS1/2 at Ser363 inhibits its translocation into the nucleus.",
Vasopressin-mediated increase in Aqp2 gene transcription. Vasopressin increases AQP2 protein abundance in collecting duct cells, largely through its effect to activate transcription of the Aqp2 gene [(Yasui, 1997), (Matsumura, 1997), (Christensen, 1998), (Hasler, 2005), (Sandoval, 2016)]. The increase is chiefly due to an increase in transcriptional elongation that is selective for the Aqp2 gene (Sandoval, 2016) and is strictly dependent on protein kinase A (Isobe, 2017). Although there has been much speculation about a possible role of the b-ZIP transcription factor CREB, recent evidence shows that CREB does not bind within 390 kb the Aqp2 gene (Jung, 2018). The above table shows phophopeptides from proteins involved in regulation of transcription that are altered in abundance in response to dDAVP in rat IMCD suspensions in the present study. Of note, of the 13 proteins pinpointed in this way, 5 are elements of the canonical Wnt signaling pathway or regulators of β-catenin abundance in the cytosol and nucleus (Apc, β-catenin, Lrrfip2, Pip5k1a, and presenilin-1 [Psen1]). The Ser522 phosphorylation site in β-catenin is increased in abundance by vasopressin as seen in prior studies [(Bansal, 2010), (Rinschen, 2010), (Bolger, 2012)]. It is a known PKA site, the phosphorylation of which increases the transcriptional activity (throughTCF/LEF transactivation) of β-catenin by increasing its stability and enhancing its translocation into the nucleus (Taurin, 2006).
Schenk et al (Schenk, 2012) showed in cultured collecting duct cells that β-catenin translocates to the nucleus in response to vasopressin. It seems plausible therefore that vasopressin could regulate gene expression in the IMCD in part through modulation of Wnt/β-catenin signaling. Besides β-catenin, an additional important transcriptional coactivator in the renal collecting duct is Yap1. This protein underwent an increase in phosphorylation at Ser363, one of several sites known to be phosphorylated by the basophilic protein kinases Lats1 and Lats2 (Ser381 in human) as part of the Hippo signaling pathway (Zhao, 2010). It is unclear whether vasopressin increases Ser363 phosphorylation in Yap1 by activating Lats or whether it increases because of PKA cross-reactivity at the Ser363 site. A negative regulator of Lats, Ajuba (also called ‘JUB’), underwent an increase in phosphorylation in response to vasopressin in the present study, although it is unclear whether this phosphorylation event affects Lats activity. Either way, activation of Hippo signaling in response to vasopressin could account in part for the observation that vasopressin can increase IMCD proliferation in intact mouse kidneys (Cai, 2007).
