Who am I and why am I here?
Long-time collaborator of Geoff Brown’s
Helped with some EM pictures
Helped with analysis of the relationship between proliferation and differentiation during
Variant cell lines from the human promyelocyte line HL60. Leuk Res. 1982 6:491-8.
Cell proliferation and CD11b expression are controlled independently during HL60 cell
differentiation initiated by 1,25 alpha-dihydroxyvitamin D3 or all-trans-retinoic acid.
Exp Cell Res. 2001 266:126-34.
HL60 cells halted in G1 or S phase differentiate normally. Exp Cell Res. 2002 15;281:2838.
Cell differentiation and proliferation - simultaneous but independent? Exp Cell Res. 2003
The sequential determination model of hematopoiesis. Trends Immunol. 2007 28:442-8.
Versatility and nuances of the architecture of haematopoiesis - Implications for the
nature of leukaemia. Leuk Res. 2012 36:14-22.
Tried to see how inositol phosphates might be implicated in myeloid differentiation. We
obtained some interesting but still unexplained results.
Inositol lipids and phosphates in the regulation of the growth and differentiation of
haemopoietic and other cells. Phil Trans R Soc B. 1990 327:193-207.
Changes in the levels of inositol lipids and phosphates during the differentiation of
HL60 promyelocytic cells towards neutrophils or monocytes. Proc Biol Sci. 1991 245:193201.
Comparison of the levels of inositol metabolites in transformed haemopoietic cells and
their normal counterparts. Biochem J. 1993 289:667-73.
Intracellular concentrations of Ins, GroPIns and InsP5 increase during haemopoietic cell
differentiation. Biochim Biophys Acta. 1994 1222:101-8.
What are inositols? Myo-inositol and others
• There are 9 isomeric inositols
(hexahydroxycyclohexanes). They are small,
sugar-like (C6H12O6), and very stable
• Nature mainly uses myo-inositol (Ins) - but
some others too (neo, scyllo, D-chiro, muco,
epi) – s denote OH inversion cf. Ins
Direct synthesis supplies only myoinositol
• Ins is made by a single short route from
• myo-inositol 3-phosphate synthase (MIPS,
above) plus Ins monophosphatase (InsPase)
• All MIPSs are related
Ins and Ins lipids: 1850-2000
• 1850-1942 – Ins discovered and structure
• 1930-50s - Ins in mycobacterial lipids, and then in
plant and animal lipids (Anderson & Roberts, Klenk,
Faure & Morelec-Coulon).
• 1940s – Ins in brain lipids: some lipid has an Ins:P
ratio of ~2 (Folch).
• 1950s – PtdIns turnover increases when secretory
tissues stimulated (Hokins) - but why?
• 1960s – Three lipids: PtdIns, PtdIns4P and
• Mid-1980s – PLC/Ins(1,4,5)P3/DAG signalling
pathway established (we thought we had ‘finished’).
• Since 1988 – more lipids, and many more functions
– notably in signalling (PI3K) and membrane
Ins S’lipid anchors
The final (?) phosphoinositide complement:
PtdIns, 3 x PtdInsP, 3 x PtdInsP2, PtdInsP3
Polyphosphoinositide locations and functions – McCrea &
de Camilli, Physiology (Bethesda), 2009, 24, 8-16
- PtdIns is in all membranes (made in ER)
Major functions in Eukaryotes
PtdIns - abundant membrane lipid
PtdIns4P - membrane traffic regulator
PtdIns5P – emerging . . . .
PtdIns3P and PtdIns(3,5)P2 - membrane
traffic regulators – and more (later)
• PtdIns(4,5)P2 - target of phospholipase C
action and Type I PI3K action; cytoskeletal
and ion channel regulator; needed for
• PtdIns(3,4,5)P3 (from PtdIns(4,5)P2) signalling, late in eukaryote diversification.
Finally, focus on PtdIns(3,5)P2
Slow growth Defective
Mutants of Fab1
faults caused by
failure to make
Dictyostelium discoideum PIPkIII
• Gene DDB0204693, same domain structure as other
• PIPkIII disrupted by insertion of blasticidin resistance
construct, checked by sequencing around insertion
Some behaviours remain normal
• Spore germination
PIPkIII- cells grown in suspension
are more vacuolated than normal