Role of a pro-sequence in the secretory pathway of prothyrotropin-releasing hormone.
The biogenesis of rat thyrotropin releasing hormone (TRH) involves the processing of its precursor (proTRH) into five biologically active TRH peptides and several non-TRH peptides where two of them had been attributed potential biological functions. This process implicates 1) proper folding of proTRH in the endoplasmic reticulum after its biosynthesis and exit to the Golgi apparatus and beyond, 2) initial processing of proTRH in the trans Golgi network and, 3) sorting of proTRH-derived peptides to the regulated secretory pathway. Previous studies have focused on elucidating the processing and sorting determinants of proTRH. However, the role of protein folding in the sorting of proTRH remains unexplored. Here we have investigated the role in the secretion of proTRH of a sequence comprising 22 amino acid residues, located at the N-terminal region of proTRH, residues 31-52. Complete deletion of these 22 amino acids dramatically compromised the biosynthesis of proTRH, manifested as a severe reduction in the steady state level of proTRH in the endoplasmic reticulum. This effect was largely reproduced by the deletion of only three amino acid residues, 40PGL42, within the proTRH31-52 sequence. The decreased steady state level of the mutant DeltaPGL was due to enhanced endoplasmic reticulum-associated protein degradation. However, the remnant of DeltaPGL that escaped degradation was properly processed and sorted to secretory granules. Thus, these results suggest that the N-terminal domain within the prohormone sequence does not act as "sorting signal" in late secretion; instead, it seems to play a key role determining the proper folding pathway of the precursor and, thus, its stability.
Romero
Amparo
A
Department of Medicine, Division of Endocrinology, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island 02903, USA.
Cakir
Isin
I
Vaslet
Charles A
CA
Stuart
Ronald C
RC
Lansari
Omar
O
Lucero
Hector A
HA
Nillni
Eduardo A
EA
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D017353:Gene Deletion; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D055571:Secretory Pathway; D013973:Thyrotropin-Releasing Hormone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D011498:Protein Precursors; D013973:Thyrotropin-Releasing Hormone
Endocrinology. 1995 Oct;136(10):4462-72
7664666
Biochemistry. 2007 Jan 23;46(3):640-51
17223686
J Biol Chem. 2002 Dec 13;277(50):48587-95
12270926
Endocrinology. 1996 Dec;137(12):5651-61
8940396
J Mol Biol. 1981 Jan 5;145(1):251-63
7265199
Curr Opin Chem Biol. 1998 Feb;2(1):31-9
9667917
J Biol Chem. 1998 Aug 14;273(33):21025-30
9694854
Annu Rev Neurosci. 1992;15:57-85
1575450
Endocrinology. 2007 Sep;148(9):4185-90
17584973
J Biol Chem. 1975 Aug 25;250(16):6291-5
808541
J Biol Chem. 1997 Aug 8;272(32):19958-68
9242664
Endocrinology. 1993 Mar;132(3):1271-7
8440188
Nat Struct Biol. 2002 May;9(5):381-8
11938353
J Neurochem. 1995 Dec;65(6):2462-72
7595540
J Biol Chem. 2004 Feb 13;279(7):5488-93
14660571
J Biol Chem. 2005 Dec 2;280(48):39818-26
16204236
Protein Sci. 1996 Sep;5(9):1907-16
8880915
Endocrinology. 1993 Mar;132(3):1260-70
8440187
J Biol Chem. 2002 May 24;277(21):18245-8
11923277
Annu Rev Cell Dev Biol. 2003;19:649-76
14570585
Proc Natl Acad Sci U S A. 2002 May 14;99(10):6619-24
11997470
FASEB J. 2006 Oct;20(12):1954-63
17012247
Proteins. 1991;9(2):90-8
2008436
J Biol Chem. 1989 Dec 25;264(36):21529-35
2513321
Biophys J. 2003 Aug;85(2):1215-22
12885665
Mol Biol Cell. 2007 Feb;18(2):455-63
17108324
Proc Natl Acad Sci U S A. 1987 Oct;84(19):6663-7
3477797
Endocr Rev. 1999 Oct;20(5):599-648
10529897
J Biol Chem. 1996 Sep 13;271(37):22736-45
8798448
J Biol Chem. 1999 May 14;274(20):14040-5
10318817
Brain Res. 1999 Nov 27;848(1-2):45-62
10701998
Science. 1997 Nov 14;278(5341):1300-5
9360928
Proc Natl Acad Sci U S A. 1970 Aug;66(4):1213-9
5273450
Regul Pept. 2006 Jan 15;133(1-3):123-33
16257458
Biochemistry. 2006 Dec 26;45(51):15468-73
17176068
J Biol Chem. 1993 Jan 25;268(3):1763-9
8380577
Mol Biol Cell. 2000 Jun;11(6):1959-72
10848622
Nat Rev Mol Cell Biol. 2003 Mar;4(3):181-91
12612637
Annu Rev Physiol. 1988;50:309-21
2897826
J Biol Chem. 1998 Jul 31;273(31):19453-8
9677365